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THE UNIVERSITY OF ALBERTA 


DEHYDROGENATION OF n-PROPANOL AND PROPIONALDEHYDE 
WITH A CHROMIA CATALYST 


A THESIS 

SUBMITTED TO THE FACULTY OF GRADUATE STUDIES 
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE 
OF MASTER OF SCIENCE IN CHEMICAL ENGINEERING 


DEPARTMENT OF CHEMICAL AND PETROLEUM ENGINEERING 

by 

KENNETH THOMAS HANSEN, B.Sc. 

EDMONTON, ALBERTA 


JUNE, 1960 





ABSTRACT 


The vapor phase catalytic dehydrogenation of normal propanol and 
propionaldehyde in a fluidized bed of chromic oxide on inactive alumina 
was studied. The superheated vapors were used to fluidize the catalyst 
of size range -40 mesh in a 2 inch I.D. reactor. 

Operating conditions were varied over the following ranges: 

Temperature - 375 to 525°C. 

n-Propanol Feed Rate - 6.70 to 15.92 gm-moles/hr. 

n-Propionaldehyde Feed Rate - 6.31 to 7.15 gm-moles/hr. 

Superficial Linear Gas Velocities -0.175 to 0.398 ft/sec. 

The experimental equipment consisted of a stainless steel reactor, 
suitable for bed heights up to 40 inches, and associated preheating and 
condensing assemblies. Chromatographic analytical methods were used for 
quantitative determinations of reaction products. 

Thermodynamic equilibrium constants have been determined for the 
dehydrogenation of normal propanol and indicate that the reactions under¬ 
taken are thermodynamically feasible. 

Conversions and reaction efficiencies of the reactions are presented. 
These results show that low conversions were effected by the chromia catalyst 
as compared to similar work by other investigators using zinc oxide catalyst. 
The dehydrogenation of n-propanol was shown to follow a first order reaction 
and reaction rate was found to vary with temperature as indicated by the 


Arrhenius equation. 





ACKNOWLEDGEMENTS 


The author feels deeply indebted to Dr. D. B. Robinson of 
the Department of Chemical and Petroleum Engineering, University of 
Alberta, who directed the research program and whose efforts contributed 
greatly to its success. 

Acknowledgement is gratefully made to Dr. E. L. Tollefson of 
Canadian Chemical Company Limited, for valuable discussions regarding 
this study. 

Appreciation is also expressed to Mr. D. Shaw, who assisted 
with analyses, and to Mr. R. Kirby for his assistance during construction 
of the apparatus. 

The financial support provided by Canadian Chemical Company 
Limited is gratefully appreciated. 











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1 


TABLE OF CONTENTS PAGE 

LIST OF TABLES . iii 

LIST OF FIGURES . iv 

LIST OF PLATES . v 

LIST OF SYMBOLS . v 

INTRODUCTION . 1 

THEORY .. 3 

1. Dehydrogenation of Alcohols . 3 

2. Fluidization . 6 

3. Fluidized Catalytic Dehydrogenation of Alcohols . 8 

EXPERIMENTAL PROCEDURE . 10 

1. Experimental Apparatus . 10 

(a) Reactor ... 10 

(b) Preheater . 14 

(c) Temperature Measurements . 15 

(d) Pressure Measurements . 17 

(e) Condensing System . 17 

(f) Gas Sampling and Measurement . 18 

(g) Alcohol and Propionaldehyde Feed System . 18 

(h) Air and Nitrogen Purge System . 21 












































- ii - 

PAGE 

2 . Experimental Technique ....... 21 

(a) Operation of Equipment .... 21 

(b) Preparation of Catalyst . 22 

(c) Analyses of Products ..... 22 

i) Liquid Products . 22 

ii) Gaseous Products ...•. 23 

EXPERIMENTAL RESULTS .•... 26 

1. Conversions and Reaction Efficiencies ... 26 

2. Order of Reaction ..... 34 

3. Thermodynamic Equilibria of Chemical Reactions . 36 

4. Condition of Equipment ... 38 

CONCLUSIONS . 40 

1. Validity of Results .-. 40 

2. Summary of Experimental Results . 40 

BIBLIOGRAPHY . 43 

APPENDICES. 44 

A. Thermodynamic Study of Reaction Equilibria . 45 

B. Sample Calculations . 50 

C. Experimental Data . 53 























. 




























Ill 


LIST OF TABLES 

TABLE • PAGE 

I Analyses of Liquid Products ... 54 

II Analyses of Gaseous Products . 55 

III Operating Conditions and Material Accountabilities 

Dehydrogenation of n-Propanol . 56 

IV Operating Conditions and Material Accountabilities 

Dehydrogenation of Propionaldehyde . 57 

V Calculations of Conversions and Reaction Efficiencies 

Dehydrogenation of n-Propanol . 58 

VI Calculations of Conversions and Reaction Efficiencies 

Dehydrogenation of Propionaldehyde . 59 

VII Calculations of Log Concentration of Unchanged 
n-Propanol and Time of Reaction 

Dehydrogenation of n-Propanol . 60 

VIII Calculations of Variation of the Rate of Dehydrogenation 
of n-Propanol with Temperature 

. Dehydrogenation of n-Propanol . 61 

IX Calculations of Predicted Moles Hydrogen and 
Actual Moles Hydrogen Evolved 

Dehydrogenation of n-Propanol ...J. 62 












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IV 


LIST OF FIGURES 

FIGURE PAGE 

1 Schematic Apparatus Assembly . 11 

2 Detailed Diagram of Reactor . 13 

3 Wiring Diagram of Thermocouple System . 16 

4 Detailed Diagram of Gas Sampling Apparatus . 19 

5 Variation of n-Propanol Conversion with Temperature 

Dehydrogenation of n-Propanol . 28 

6 Variation of Propionaldehyde and Diethyl Ketone Reaction 

Efficiencies with Reaction Temperature 

Dehydrogenation of n-Propanol .:. 29 

7 Variation of Propionaldehyde Conversion and Diethyl 

Ketone Reaction Efficiency with Reaction Temperature 
Dehydrogenation of Propionaldehyde . 31 

8 Percentage Propionaldehyde Conversion 

Dehydrogenation of n-Propanol and Propionaldehyde 33 

9 Determination of Reaction Order 

Dehydrogenation of n-Propanol . 35 

10 Variation of Rate of Reaction with Temperature 

Dehydrogenation of n-Propanol . 37 

11 Comparison of Moles Hydrogen From Reactions: 

n-PrOH-PrH + H 2 

2n-PrOH — DEK + CO + 3H 2 

With Actual Moles Hydrogen in Off Gas 

Dehydrogenation of n-Propanol . 41 














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LIST OF PLATES 

PLATE PAGE 

1 Photograph of Experimental Equipment . 12 

2 Gas Sampling Apparatus . 20 

3 Microbellows Positive Displacement Pump . 20 

4 Top View of Upper Catalyst Filter . 39 

5 Bottom View of Upper Catalyst Filter . 39 

LIST OF SYMBOLS 

n-PrOH - Normal Propanol 

PrH - Propionaldehyde 

DEK - Diethyl Ketone 

















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1 


INTRODUCTION 

There have been extensive investigations of the dehydrogenation 
of alcohols in fixed bed reactors (1,4,5,8). Several catalysts, mainly 
of the metallic oxide type, have been studied and optimum conditions 
and reaction selectivities reported. In the case of dehydrogenation of 
alcohols utilizing the fluidized catalyst technique, very little similar 
data is available (2,9). 

The fluidized catalytic bed has definite advantages, particularly 
for highly endothermic reactions such as the one undertaken in this study. 
Fluidization provides a means of carrying out processes in which large 
amounts of heat are released or required without the danger of local 
overheating. Heat transfer coefficients for a fluidized bed are much 
higher than normal gas film coefficients (7), due to the rapid circulation 
of particles within the reactor. The high heat transfer rates in the 
system coupled with a high thermal conductivity facilitates the uniform 
control of temperature, making possible the attainment of isothermal 
conditions. Isothermal conditions in a fluidized reactor may be of 
particular value in cases where a reaction is very temperature sensitive, 
i.e., favorable conditions can be maintained at the inlet without fear of 
running into unfavorable conditions at the outlet of the bed. A much greater 
solid surface for contacting the flowing medium is provided by the movement 
of the fine solid particles in the fluidized bed than in fixed bed reactors. 


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In cases where continuous regeneration and reactivation of the catalyst 
are necessary because of fouling, the fluidized bed has proven to be of 
considerable use. 

Komarewsky and Coley (5) reported that primary alcohols of 
n-carbon atoms are readily converted to symmetrical ketones of 2n-l 
carbon atoms by vapor-phase contact with chromia catalysts. In view of 
these results the dehydrogenation of n-propanol in a fluidized bed using 
a chromic oxide catalyst on inactive alumina support was undertaken to 
determine the extent to which the reaction to the symmetrical ketone, 
diethyl ketone, could be promoted. Ketones and mixtures of ketones have 
achieved commercial importance for selective solvent processes such as 
the solvent dewaxing of lubricating oils. 

Factors such as backmixing, which results in high concentrations 
of products throughout a fluidized bed, and the variable quality of 
fluidization can make reaction predictions uncertain. 



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THEORY 

I . Dehydrogenation of Alcohols 

The dehydrogenation of alcohols was first studied by Ipatieff, 
who converted methyl, ethyl, Isopropyl, isobutyl, and isoamyl alcohols 
to aldehydes and ketones using such catalysts as platinum tubes, zinc 
rods, and brass turnings at suitable reaction temperatures. Later, the 
majority of the studies of dehydrogenation utilized metallic oxides on 
mixtures of these oxides as the catalyst. The preparation of ketones by 
dehydrogenation of secondary alcohols over various catalysts has been 
covered in standard reference books on catalysis. 

Komarewsky and Coley (5) have found that primary alcohols of 
n-carbon atoms are readily converted to symmetrical ketones of 2n-l carbon 
atoms by vapor-phase contact with various catalysts. In the presence of 
a chromia catalyst, these workers proposed a mechanism for the conversion 
of the symmetrical ketones as follows: 

1. Dehydrogenation of the alcohol to the aldehyde. 

2. Aldol condensation of the aldehyde. 

3. Removal of carbon monoxide from the -CHO group of the aldol leaving 
a secondary alcohol. 

4. Dehydrogenation of this alcohol to the corresponding ketone. 

Komarewsky and Coley studied the dehydrogenation of primary 
alcohols ranging from n-propanol to n-octadecyl alcohol. These dehydro¬ 
genations were performed in a fixed bed of chromic catalyst and at a 













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temperature of 400°C. The molal conversion of reacted alcohol to ketone 
exceeded 50 per cent in most cases. The mechanism proposed was supported 
by an investigation of intermediates: 

"In a preliminary consideration of the reaction mechanism, 
aldehydes and aldols seem to be logical intermediates. It was 
found that aldehydes undergo the same type of condensation, 
producing yields considerably superior to those obtained from 
the corresponding alcohol. When the aldols of n-buiylaldehyde 
and n-heptaldehyde were subjected co the same reaction conditions, 
excellent yields of ketone were produced directly by a catalytic 
decomposition reaction. The order of conversion of the reactants 
to ketones was aldol aldehyde alcohol." 

To substantiate the aldol intermediate mechanism, a deuterium tracer 

technique was employed and it showed that the intermediate forms did 

exist. 


A generalized theory of dehydrogenation of alcohols has been 
reported by Church and Joshi (1). They have proposed that the reaction 
proceeds through the formation of a complex between the alcohol and the 
catalyst, M: 

H H 

R - C - H + 2M-R - C - H - M 

6 - H O-H-M 

Some generally accepted theories (1) concerning dehydrogenation 
reactions are: 

1. The reaction follows a pseudo first order reaction rate equation. 

2. The energy of activation for dehydrogenation is constant for a 
given catalyst but varies with the type and method of preparation 
of it. 

3. The reaction rate is dependent on temperature as stipulated by the 
hypothesis of Arrhenius and is consistent with the constancy of the 


energy of activation. 




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4. The alcohol molecules are first adsorbed on the surface of the 
catalyst with the hydroxyl groups parallel to the surface and the 
rest of the molecules perpendicular to it. 

5. The reaction velocity is independent of the pressure of the 
system. 

The fluid bed dehydrogenation of n-propanol was studied by 
Tollefson (9) utilizing a zinc oxide on alumina catalyst. To explain 
information obtained from mass spectrographic and infra-red analyses, the 
following series of reactions were proposed: 


1. C1I 3 - Cll 2 ~ CH 2 OH —CH 3 - CH 2 - c s = 0 + H 2 

S H 

propionaldehyde 

z° /° 

2. 2 CH 3 - CH 2 - -^ CH 3 - CH 2 - CH - CH - C ' 

n h OH CH 3 H 

2 - methyl, 3 - hydroxy pentaldehyde 

3. CH 3 - CH 2 - CH - C1I - C -a- CH 3 - CH 2 - CH = C - C + H 2 0 

OH CH 3 H CH 3 H 

2 - methyl penten - 2 - al 


4. CH 3 - CH 2 - CH - CH - C - 
dm 6 h 3 v h 


CH 3 - CH 2 - CH - CH 2 - CH 3 -I- CO 


OH 


3 - pentanol 


5. CH 3 - CH 2 - CIi - CH 2 - CH 3 —CH 3 - CH 2 - C - CH 2 - CH 3 + H 2 


OH 


diethyl ketone 


6. CH 3 - 


—C1I 2 = CH 
pentene - 1 


CH 

d)H 


ol 


CH 2 - CH 3 + H 2 
3 


CHp - CH - CH 2 - CIi 3 
d)H 








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7. CH 3 - CH 2 - CH - CH 2 - CH 3 —► CH 3 - CH = CH - CH 2 - CH 3 + H 2 0 

OH 

pentene - 2 

8. CO + H 2 0 —► C0 2 ■+■ H 2 

9. CH 3 - CH 2 - CH 2 OH —CH 3 - CH = CH 2 -F H 2 0 

Reactions 1, 2, 4, and 5 were reactions reported by Komarewsky 
and Coley (5). 

Neish (8) reported that the dehydrogenation of several alcohols 
and glycols, in the gaseous state, was a first order process obeying 
the Arrhenius relation for variation of rate with temperature. A porous 
copper catalyst was found to be the most satisfactory in these experiments 
which were carried out in a fixed bed reactor at temperatures of 180 to 
370°C. 

2. Fluidization 

Since the introduction of the concept of fluidized solids by the 
Standard Oil Development Company, there has been considerable development 
and application of the technique. The unique properties of fluidized 
catalytic beds have made several important industrial reactions feasible. 

Fluidization describes an operation which pertains to a mode of 
granular solids - fluid contacting. If a fluid passes upwards through a 
bed of particles, the pressure drop will be the same as for downward flow 
at low rates, but when the drag due to friction equals the apparent weight 
of the particles, the bed starts to expand. This process continues 
until the bed has assumed the loosest stable form of packing. If the 
velocity is increased still further, the individual particles separate from 
one another and become freely supported in the fluid and the bed is said 











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to be fluidized. Solids in the fluidized state possess a degree of 
mobility that is comparable to that of liquids. 

Fluidized systems are extensively used because of the high rates 
of heat transfer and the uniform temperature within the bed, and the 
high coefficients for transfer from the bed to the walls of the containing 
vessel. It is generally suggested that the presence of the particles near 
the wall breaks up the laminar sub-layer which would normally provide a 
resistance to heat transmission. Heat transfer characteristics of fluidized 
beds internally and externally heated have been determined by Mickley and 
Trilling (7). The coefficients were 3 to 70 times greater than in similar 
tubes without particles. Radial and longitudinal temperature gradients 
were shown to be virtually eliminated. 

Summarizing, the chief advantages of the fluidized solids method 
are: (6) 

1. Continuous operation. Since spent solids are easily removed from 
a system, continuous operation may result. The spent solids may 
then be reactivated or replaced by fresh solids. 

2. Flat temperature profiles. Intense particle and gas agitation in 
the bed produces a uniform temperature distribution, longitudinally 
as well as horizontally. 

3. High heat transfer coefficients. The particle motion past the 
heat transfer surfaces results in comparatively high wall to bed 
heat transfer. 

4. Relatively low pressure drops through the fluidized bed reactor. 











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Chief disadvantages of the method are: 

1. Concurrent solid and gas flow. In this way driving forces may 
be adversely affected in physical operations. 

2. Severe erosive damage to reactors and transfer accessories. 

3. Requirements for catalyst recovery equipment because of eluiriation. 

4. Attrition of the catalyst and its replacement cost. 

Gilliland and Mason (3) investigated gas and solid mixing in 
fluidized beds by tracer gas and heat flow methods and concluded that 
backmixing of gas was relatively low in the small diameter reactors employed. 
It was also concluded that for reactors with high aspect, i.e. L/D ratios, 
reaction rate studies could be correlated on the basis of piston flow 
neglecting mixing and that isothermal conditions of the fluidized bed 
result from circulation of solids rather than from gas mixing. 

3. Fluidized Catalytic Dehydrogenation of Alcohols 

With the exception of petroleum refining fluidized catalyst 
studies, the organic reactions carried out in fluidized catalyst beds 
are relatively few. De Q. Jones (2) carried out the vapor phase catalytic 
dehydrogenation of ethanol in a fluidized bed of reduced metallic copper. 
Nitrogen was used to fluidize the fine solid particles of the catalyst 
which were in the size range 104 - 208 microns, and were composed of 
copper on crushed commercial Boileezers. Reactor temperatures were 
varied over the range 225 to 385°C., and ethanol feed rate varied from 
0.07 to 1.. 12 moles/hr. Results showed that low rate of alcohol feed and 
temperature between 275 and 350°C. favored the formation of acetaldehyde, 

















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whereas high feed rates and lower temperatures, 225 to 260°C., effected 
high conversions to ester. A maximum total conversion of 22.7 per cent 
was obtained. 

Tollefson (9) determined conversions, reaction efficiencies 
and products when n-propanol was dehydrogenated over zinc oxide on 
inactive alumina in the fluidized state. The dehydrogenation was 
investigated at superficial gas velocities of 0.2, 0.3 and 0.4 ft./sec. 
and at reaction temperatures of 375, 425, 475, and 525°C. using a 
1.70 inch diameter fluidized bed 10 inches high. A maximum conversion 
of 95 per cent was obtained at a superficial gas velocity of 0.2 ft./sec. 
and a temperature of 525°C. The maximum diethyl ketone reaction efficiency 
of 15 per cent was obtained at these same conditions. The dehydrogenation 
of secondary butanol was also studied by the above investigator utilizing 
similar catalysts and conditions as for the dehydrogenation of n-propanol. 








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EXPERIMENTAL PROCEDURE 

1. Experimental Apparatus 

A schematic diagram and a photograph of the experimental equipment 
appear in Figure I and Plate I respectively. The equipment used is 
similar to that used by Tollefson (9) for his study of the dehydrogenation 
of secondary butanol. 

(a) Reactor 

Figure 2 is the detailed diagram of the reactor. It was 
constructed of Type 316 stainless steel except for the low carbon 
steel lap joint flanges. A 4 foot section of 2 inch standard pipe 
was used as the main reactor section enlarging into a 2 foot section 
of 4 inch diameter disengaging zone. The catalyst support grid plate 
consisted of a circular section of 1/8 inch porous stainless steel 
supplied by Micrometals Company. The grid plate was recessed into 
the flange in the lower reactor. The disengaging section was provided 
with a baffle plate and porous stainless steel filter to eliminate 
carry-over of the catalyst into the condensing system. 

Pressure taps were located 1.5 inches above the lower grid 
plate of the reactor and in the disengaging zone. To prevent catalyst 
from moving into the manometer lines, small porous stainless steel 
filters were fitted into the pressure taps. 




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PLATE 1 - PHOTOGRAPH OF EXPERIMENTAL EQUIPMENT 














































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FIGURE 2 - DETAILED DIAGRAM OF REACTOR 



















































































































































14 


Heat was supplied to the reactor by two 1000 watt heaters 
controlled by 1 KVA variable transformers. The heaters consisted of 
20 feet of 20 gauge nichrome electrical resistance wire strung on 
porcelain insulating beads. The winding was supported with a coating 
of Saurereisen No. 29 refactory cement. Electrical terminals were 
constructed with 14 gauge nichrome wire strung on beads and cemented 
in place by refactory cement. A 10 ampere ammeter and 10 ampere fuses 
were included in each heater circuit. Asbestos insulation was used 
as a cover for the reactor winding and the entire 2 inch reactor 
section was sheathed with corrugated aluminum sheeting. 

The disengaging zone and upper flange heater consisted of 
18 feet of 20 gauge nichrome resistance wire controlled by a 1 KVA 
variable transformer. Loose flake asbestos and fibreglass insulation 
was placed over the upper flange, but the disengaging zone was left 
uninsulated. 

(b) Preheater 

A 3 foot section of 1 inch Schedule 40 stainless steel 
pipe was threaded into the side outlet of a tee at the lower end of 
the reactor. Liquid alcohol was admitted through a 1/4 inch O.D. 
stainless steel tube silver soldered into a 1 inch stainless steel 
cap threaded to the 1 inch pipe. 

A 20 foot, 20 gauge nichrome resistance heater constructed 
and controlled similarly to the reactor heaters supplied heat required 
to vaporize the liquid alcohol and heat the vapors to the desired level 
of temperature. Asbestos insulation sheathed with aluminum sheeting 











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was used as preheater insulation. The lower reactor tee fitting 
was insulated with loose flake asbestos held in place with a formed 
sheet aluminum cover. 

(c) Temperature Measurements 

A single iron-constantan thermocouple was installed to 
measure vapor temperature in the preheater. A two hole ceramic 
insulator fitted into a 1/8 inch I.D. thin wall stainless steel tube 
supported the wires. The tube was silver soldered into a standard 
stainless 1 inch plug, extending the thermocouple junction 6 inches 
into the preheater when threaded into the lower reactor tee fitting. 

Temperature measurement in the reactor was accomplished by 
positioning an eight point thermocouple string from the upper tee 
fitting of the reactor to within 1 inch of the grid plate. A diagram 
of the thermocouple system appears in Figure 3. A common constantan 
wire extended to the lowest point of the thermocouple string; the 
iron wires extended to thermocouple junction points along the constantan 
wire. The thermocouple wires were insulated by using 1/8 inch O.D. 

2 hole ceramic insulators. The entire string was placed in a 3/8 
inch I.D. thin wall stainless steel tube which was soldered into a 
1 inch stainless steel plug. The ends of the thermocouple wires were 
attached to a nine-point junction to facilitate thermocouple dis¬ 
connection during removal of the thermocouple tube from the reactor. 

A single cold junction was held at the ice point to provide a 
reference potential. All thermocouples were connected to a Leeds and 
Northrup twelve-point recorder. A Leeds and Northrup Potiable 





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16 



Pre hea ter 


Constant an 
























































































































17 


Potentiometer connected to the remaining three recorder junctions 
was used for calibration of the recorder. 

The longitudinal temperature gradient of the bed, as indicated 
by reactor thermocouples, was controllable to approximately 2.5°C. 
at steady state conditions. This temperature variation increased 
considerably at superficial linear gas velocities below 0.175 ft./sec. 

(d) Pressure Measurement 

Pressures were measured at two points, immediately above the 
grid plate and in the disengaging zone. Filters were placed in each 
line to eliminate the flow of catalyst into the manometer. Copper 
tubing was used to connect pressure taps to two mercury manometers 
installed in the control panel. 

The pressure drop across the fluidized bed was essentially 
constant at 2.5 inches of mercury for all superficial linear gas 
velocities used in this study. The absolute pressure varied with 
gas velocity due to increased pressure drop across the upper catalyst 
trap at higher gas velocities. 

(e) Condensing System 

Two condensers of identical construction were used to condense 
hot gaseous products from the reactor. Each condenser was constructed 
by placing a nine tube bundle in a 2 foot, 2 inch I.D. copper shell. 
The tube bundle consisted of 1/4 inch copper tubing. The upper 
condenser was water cooled and situated immediately above the final 
condenser which was cooled by refrigerated ethylene glycol-water 
solution. The refrigerated coolant, circulated by means of a small 



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18 


centrifugal pump, was maintained at -16°C. A liquid product 
receiver was located below the final condenser together with an 
exit for uncondensed gases. 

(f) Gas Sampling and Measurement 

Figure 4 and Plate 2 show the apparatus used for gas sampling. 
A Redmond Model 3554, Type L, diaphragm pump was installed to boost 
gas pressure in glass sample bombs to 6 psig. The additional gas 
sample was necessary to provide sufficient gas for chromatographic 
analyses. Sample bombs were fitted with Burrell check valves for 
direct insertion into a Burrell Model K-2 Kromotog. 

An oil filled wet test meter provided with a bypass was used 
to measure the volume of the uncondensed off gas. 

(g) Alcohol and Propionaldehyde Feed System 

A calibrated Lucite tube served as a feed reservoir for a 
Research Appliances Model 1000, stainless steel, 3/4 inch microbellows 
positive displacement pump (Plate 3). The discharge line of the pump 
led to a metering needle valve located close to the preheated inlet. 
This allowed the feed to be shut off at the metering valve, limiting 
the amount of alcohol remaining in the preheater to a minimum. A 
pressure gauge located in the pump discharge line assisted in control 
of the metering valve. 

The Lucite feed tube was replaced by a calibrated glass tube 
during Runs 26 to 31 as Lucite was dissolved by the propionaldehyde 


feed used in these runs. 




J. 




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To W«t 
Test 

Meter 


19 



FIGURE 4 - PETAILED DIAGRAM OF GAS SAMPLING APPARATUS 






































20 



PLATE 3 - MICROBELLOWS POSITIVE DISPLACEMENT PUMP 

















21 


(h) Air and Nitrogen Purge System 

For initial startup and reactivation of catalyst, an air 
and nitrogen purge system was connected to the preheater. The purge 
gas flowed through a calibrated rotameter, then into a needle valve 
located near the preheater inlet. The low volume between the needle 
valve and preheater inlet insured that little alcohol backed up into 
the purge line during a run. 

2. Experimental Technique 

(a) Operation of Equipment 

Fluidization of the catalyst bed was initiated by flowing air 
through the bed at the rate of 4 - 5 cu. ft. per hour. This was con¬ 
tinued during the heating of the reactor to the desired level which 
required 4 to 5 hours. When the reactor temperature was at the 
desired point, nitrogen was flowed through the reactor to purge the 
air from the system. This eliminated a potential explosive mixture 
which could result from the hydrogen produced from the reaction and 
the oxygen in the purging air. The nitrogen purge was continued for 
15 minutes. After purging, the liquid feed pump was started and 
alcohol or propionaldehyde metered into the preheater. The microbellows 
feed pump could be adjusted for flow rates from 30 to 1500 mis./hr. by 
varying the stroke of the bellows. Back pressure of 10 - 15 psig was 
maintained in the discharge line by the adjustment of the metering 
valve. After startup, the level in the feed reservoir was checked 
over a period of time and final adjustments made to the pump to 
achieve the flow rate desired. 



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22 


When steady state conditions had been established, a one hour 
run was made. At 30 minutes an uncondensed gas sample was taken and 
pressured to 6 psig. The amount of feed, volume of off gas, weight 
of liquid sample, reactor pressures and temperatures were recorded. 

A liquid sample was taken from the liquid product and placed in 
tightly stoppered bottles which were refrigerated until chromatographic 
analyses were performed. 

(b) Preparation of Catalyst 

The chromic oxide on inactive alumina used in this study 
was prepared by impregnating inactive alumina (Norton Company) with 
chromium nitrate (Cr(N0 3 ) 2 •9H 2 0) in aqueous solution. The catalyst 
was dried and decomposed at 700°C. in a fluidizing air stream. 

The amount of chromic oxide on the inactive alumina was calcu¬ 
lated to be 6.3 per cent. A size analysis of the catalyst showed the 
size distribution to be: 

Size Range Weight % 


+ 40 



0 

- 40 

+ 

60 

6.7 

- 60 

+ 

100 

26.4 

- 100 

-1- 

200 

44.0 

- 200 



22.8 


(c ) Analyses of Products 

i) Liquid Products 

Liquid compositions were determined by analyses using 
a Burrell Model K-2 Kromotog gas chromatograph. Initially, several 
column packings and operating conditions were studied in an attempt 








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23 


to find a column or columns which would give a satisfactory 
separation of components. As many minor fractions were found to 
exist in the liquid products, particularly during high reaction 
temperature runs, this selection of a suitable column was difficult. 

A 2 1/2 meter, Apiezon L grease on crushed firebrick column was 
found to give satisfactory separation of the major components, namely 
pentene, propionaldehyde, n-propanol, and diethyl ketone. The minor 
fractions gave overlapping peaks in some cases; attempts to identify 
them gave little success. The minor fractions were classed as 
"other" in the analyses. 

The following chromatographic conditions were used. 

Column: 2 1/2 meter, Apiezon L on Firebrick. 

Column Temperature: 130°C. 

Carrier Gas: Hydrogen at 75 cc/min. 

Detector Current: 200 milliamperes. 

Sample: 5 microliters. 

Quantitative determinations were made by assuming 
that the area under any peak was proportional to the weight per cent 
of that particular component in the sample. This method, while 
unsound for analyses requiring a high degree of precision, provides 
a relatively easy means of quantitative analyses to a reasonable 
accuracy (10). In any case, a change from sample to sample is 
readily detected despite the fact that the absolute percentage value 
may be in error. Areas under the peaks were measured by use of a 
planimeter. 

ii) Gaseous Products 

A Burrell Model K-2 Kromotog gas chromatograph similar 




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24 


to the one used for liquid analyses was used for quantitative 
analyses of the uncondensed gaseous products. 

Listed below are the columns and conditions used 


and the separations achieved on each: 


1. 

Column - 

2 1/2 meter, Linde Sieve 


Column Temperature 

Room temperature 


Carrier Gas - 

Helium at 40 cc-./min. 


Detector Current - 

180 milliamperes 


S amp1e - 

3 cc. 


Separation - 

Hydrogen, Oxygen, Nitrogen, Carbon Monoxide 

2. 

Column - 

2 1/2 meter, Linde Sieve 


Column Temperature 

Room temperature 


Carrier Gas - 

Nitrogen at 40 cc./min. 


Detector Current - 

160 milliamperes 


Sample - 

3 cc . 


Separation - 

Hydrogen 

3. 

Column - 

2 1/2 meter, Apiezon M on Firebrick 


Column Temperature 

70°C. 


Carrier Gas - 

Helium at 40 cc./min. 


Detector Current - 

190 milliamperes 


S amp 1 e - 

3 cc. 


Separation - 

Hydrogen, Oxygen, Nitrogen CO (one peak), 
Carbon Dioxide, Propylene, Propionaldehyde, 
n-Propanol, "other". 


To perform 

the above three determinations from one 

s amp 1 e 

it was necessary to 

pressurize the glass sample bombs to 

6 psig 

. as discussed in the 

equipment section. In addition, the 


pressure in the bomb was found to be convenient for flushing the 
gas sampling system installed in the Burrell Kromotog. 

Calibration runs were made to improve the hydrogen 
determination. As a result, this analysis is considered to be 
the most accurate of the gaseous quantitative analyses. A similar 
calibration was attempted for carbon monoxide, however, poor cali¬ 
bration reproducibility was experienced. The poor reproducibility 





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. : 



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. 


. 





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25 


obtained for carbon monoxide determinations would indicate that 
the Linde Sieve column was possibly not inert to this component. 

No attempts were made to determine more satisfactory means of 
analyzing for carbon monoxide. The remainder of the gas was 
quantitatively analyzed by assuming that peak height was proportional 
to the volume per cent of that particular component in the sample. 

As in the case of analyses of liquid products, several unidentified 
components were classed as "other". 





26 


EXPERIMENTAL RESULTS 

1. Conversion and Reaction Efficiencies 

The analyses of liquid and gaseous products appear in Table I and 
II in the Appendix. Tables III and IV show the operating conditions and 
material accountabilities of Runs 8 to 25 and Runs 26 to 31 respectively. 
Calculated conversions and reaction efficiencies appear in Tables V and 
VI. 


Results from Runs 1 to 7, associated with the startup of equip¬ 
ment were considered unreliable and are not reported as data. During 
this period, analytical techniques and operating methods for the equipment 
were established. 

The following definitions were used in the preparation of Tables V 


and VI. 

(a) Dehydrogenation of n-propanol 

% n-PrOH Conversion = Moles n-PrQH Fed - Moles n-PrOH in Product 

Moles n-PrOH Fed 


x 100 


7 a PrH Reaction Efficiency = Moles PrH in Product x ^qq 

Moles n-PrOH converted 

°L Diethyl Ketone Efficiency = 2 x Moles DEK in Product x ^qq 

Moles n-PrOH converted 


7o PrH Conversion = Moles n-PrOH converted - Moles PrH in Product x -^qq 

Moles n-PrOH converted 


(b) Dehydrogenation of Propionaldehyde 

7. PrH Conversion = Moles PrH Fed - Moles PrH in Product . 

Moles PrH Fed 

7o Diethyl Ketone Efficiency = 2 x Moles DEK in Product x ]_qq 

Moles PrH converted 










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■' . . .. r<■ J.-i. 

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v . ■■■■..; . .... 

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: - * • •• A ......a-. . i .. (. c '. 






27 


% Material Accountability = Weight of Products x ^.00 

Weight of Feed 

Figure 5 shows the percentage n-propanol conversion for different 
operating temperatures and superficial linear gas velocities. While there 
is a marked improvement in percentage conversion from 0.3 to 0.2 ft./sec. 
superficial gas velocity, no difference was detected between the 0.3 and 
0.4 ft./sec. velocities. The superficial linear gas velocity is calculated 
on the basis of moles n-propanol fed through an empty reactor at reaction 
temperature and pressure. The actual gas velocity through the bed will 
vary with the extent of conversion of the n-propanol fed since the main 
reactions occurring are accompanied by an increase of volume. A complete 
sample calculation of superficial linear gas velocity is included in the 
Appendix. 

The percentage conversions of n-propanol shown in Figure 5 compare 
very closely to results of Tollefson (9) over the same temperature range. 

It must be noted, however, that the zinc oxide on inactive alumina catalyst 
bed used by the above investigator was only 10 inches high so that the 
contact time experienced for runs reported herein was much greater. 

In Figure 6, a plot of propinnaldehyde and diethyl ketone reaction 
efficiencies is given for the reaction conditions studied. In this case, the 
propionaldehyde reaction efficiencies reported by Tollefson (9) are 
approximately 20 per cent higher than reaction efficiencies reported in this 
study; the diethyl ketone efficiencies are quite similar. For reasons 
mentioned above, it appears that conversions and reaction efficiencies 
obtained in this study are considerably lower than dehydrogenation performed 



. 













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t 








7 


A . i I I 


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. i. 




>; 




V 


.. i oj ; « 


; 


a . 


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i 


- 


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FIGURE 


28 


m 


o 

0) 

in 


CM 


ro 


o 

CD 

to 



in 

CM 

in 


o 

o 


in 

N- 

< 3 - 


o 

o 


o 

<T> 


O 

00 


o 

r- 


o 

co 


o 

m 


o 

M- 


O 

ro 


o 

CM 


N0ISb3AN00 "lONVdOdd % 


REACTION TEMPERATURE 













29 









30 


in fluidized beds using zinc oxide catalyst. Recent work by Tollefson (9) 
has shown that catalyst containing a high concentration of chromia does 
not improve the results obtained in fluidized bed alcohol dehydrogenations. 

In an attempt to obtain a further understanding of the mechanism 
of dehydrogenation of n-propanol, Runs 26 to 31 were conducted using 
propionaldehyde feed (88.2 per cent propionaldehyde). Komarewsky and 
Coley (5) proposed that the aldehydes were intermediates in the dehydro¬ 
genation of alcohols. Komarewsky's work showed that dehydrogenation of 
aldehydes gave higher conversions to ketones than did dehydrogenation of 
corresponding alcohols. Figure 7 shows the total percentage conversion 
and diethyl ketone reaction efficiency for the range of operating conditions 
chosen -- 0.2 ft./sec. linear superficial velocity and 375, 425, 475, and 
525°C. 

While reaction efficiency to diethyl ketone was slightly higher 
during runs using propionaldehyde feed, the total percentage conversion 
is very low compared to the n-propanol dehydrogenation. Despite the higher 
conversions to ketone reported by Komarewsky and Coley (5) when using 
aldehyde feed, these results are quite plausible. The total conversion 
of n-propanol includes the conversion to propionaldehyde as well as 
propionaldehyde to diethyl ketone and other unidentified products. In Runs 
26 to 31, the total conversion includes only the conversion from aldehyde 
to ketone and other products; apparently the more difficult reaction to 
complete. Figure 7 shows that the diethyl ketone efficiency was favored 
by increasing temperature, a conclusion which is not apparent from the 
dehydrogenation of n-propanol (Figure 6). 







u 






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A 


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FIGURE 


31 


N- 


co 

x 

LlJ 

> 

z 

o 

o 

LlJ 

Q 

> 

X 

LlI 

Q 


O 

CL 

O 

x 

Ol 


o 

I- 

<r 

cr 

< 

> 


>- 

o 

z 

LlI 

O 

Ll 

Ll 

LlI 


LlI 

O 

>- 

X 


o 

< 

LU 

x 


UJ 

z 

o 

h- 

LlJ 


_l 

>- 

X 

h- 

LlJ 

Q 


O 

z 

< 


Q 


LU 

X 

3 

I- 

< 

X 

LlI 

X 


o 

CL 

o 

X 

x 


XI O 


O 


I- 

o 

LU 

X 


< 

z 

LU 

CD 

O 

X 

O 

> 

X 

LU 

Q 


>- 

O 

z 



in 

CM 

ID 


to 

l'- 


lO 

CM 

M- 


to 

N- 

ro 


6 

o 


UJ 

X 

3 

\- 

< 

X 

UJ 

X 

2 

UJ 

h- 


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Ul 

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o o o o o 

cr> CD I s - CD 10 


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M- 


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o o o 

rO cm — 


A0N3I0I333 NOIIDV 3 d >130% B N0ISd3AN0D H^d % 


















32 


To achieve a more satisfactory means of comparing the 
dehydrogenation of n-propanol and propionaldehyde, propionaldehyde 
conversions from the n-propanol dehydrogenation were calculated. This 
conversion was defined as the percentage moles of propionaldehyde converted 
to diethyl ketone and "other" from the moles propionaldehyde available 
for reaction. The moles propionaldehyde available for reaction was 
estimated from the conversion of n-propanol, i.e. this assumes that all 
n-propanol converted goes through the propionaldehyde intermediate and 
that no "other" compounds are formed directly from n-propanol. The 
propionaldehyde percentage conversions is then calculated as: 

% PrH Conversion = Moles n-PrOH converted - Moles Prll in Product x -^qq 

Moles n-PrOH converted 

Propionaldehyde conversion from Runs 8 to 25 are shown in Figure 8. 

In addition, the conversion from propionaldehyde dehydrogenations. Runs 
26 to 31, is included. The propionaldehyde conversion of Runs 26 to 31 
is considerably lower than conversion obtained in Runs 8 to 25 over the 
temperature range 375 to 475°C. Conversions for Runs 8 to 25 show a 
minimum at 450°C. for all superficial linear velocities studied. It is 
proposed that the presence of the aldehyde depresses the activity of 
the catalyst and that higher temperatures favor higher conversions of 
propionaldehyde to diethyl ketone. At the lowest temperature studied, 

375°C., only small amounts of propionaldehyde are formed, but as the 
temperature increases the propionaldehyde concentration increases lowering 
the catalyst activity. As the reaction temperature increases, this reduced 
catalyst activity is offset by the effect of reaction temperature on conversion 
For Runs 26 to 31, the propionaldehyde concentration is fixed by the feed 
















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V..; r.: ; 




:) . 


i ... . .. ; : 




. • • . 


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(. 






• <: : 


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A . 




c 








33 



REACTION TEMPERATURE 






* 


34 


composition and the curve reflects only the influence of temperature on 
propionaldehyde conversion. 

The effect of propionaldehyde on catalyst activity was also 
encountered by Neish (8), who stated that: 

"One might be tempted to conclude .•. that the primary 

alcohol group required more energy for activation than the 
secondary alcohol group. This is misleading, however, since 
in reality the primary group is dehydrogenated just about as 
readily as the secondary. The differences observed are 
caused by reversible combination of the products of dehydro¬ 
genation with the catalyst,* The aldehydes show a marked 
tendency to lower the activity of the catalyst as does diacetyl, 
while the simple methyl ketones have little or no effect." 


2. Order of Reaction 

Previous investigations (1,8) have shown that the dehydrogenation 

of alcohols over many catalysts followed a first order rate equation. 

Also, the same investigators found that all alcohols studied obeyed 

the Arrhenius relation for variation of rate with temperature. 

Neish (8) plotted log C, the fraction unchanged, versus 

t, time of reaction and obtained linear plots for one temperature indicating 

that the reaction was of the first order type. A similar calculation was 

o 

performed for the n-propanol dehydrogenation at 375, 425, 475, and 525 C. 
(Table VII). A constant fluidized bed height was assumed for calculation 
of reaction time. The plots (Figure 9) indicate that a first order 
reaction was experienced in this study. 


* Catalysts studied by Neish were copper and nickel on various 


supports prepared by several methods. 






35 


C£ 

UJ 

Q —I 


£E O 



HO J d u Q39NVH0Nn NOIJLVU1N39N00 903 


T I'M E OF REACTION ~ SECONDS 






36 


The rate constant, k, is defined by the familiar expression: 

2.303 1 

k = t log c 

where t and C are reaction time and fraction unchanged. Table VIII 
shows the calculation of log k for the four reaction temperatures 
studied. The plot of log k versus Js is shown in Figure 10. The 
linear relation between log k and was found to hold indicating that 
the reaction rate constant is dependent on temperature as indicated by 
the Arrhenius equation. 

The calculations described above are not strictly true since 
the formation of products in the reactor does not occur instantaneously. 
Actually, the composition of the gas varies along the reactor as products 
are formed according to the first order relation. Another assumption 
used is that backmixing in the fluid bed is negligible. No attempt 
was made to account for these deviations from the idealized case. 

3. Thermodynamic Equilibria of Chemical Reactions 

For the purpose of the thermodynamic analysis, reaction equilibrium 
constants for two reactions were considered: 


PrOH -PrH + H 2 -- (1) 

2PrOH ——► DEK + CO + 3H 2 ..-.. (2) 


Calculations of the equilibrium constants, K a , for reaction temper¬ 
atures of 375, 425, 475, and 525°C. for each of these reactions are shown 
in the Appendix. Since complete thermodynamic properties of diethyl ketone 
were not available, estimates were made to determine the free energy of 






- 

. 

: t j, .3 _ . : .. .' : 

. . . 

. > : ’ J .Kg 1 tt... . 

. ffi.., 1 ;. t#i, * 

; _Jp.Ci'l ,jl1;, 

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, . ... : .1 • ■' ■ : .. 

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. : ... . :. . . 


r- ■ ; : 









37 



1.25 1.30 1.35 1.40 1.45 1.50 1.55 





















38 


formation and heat of formation for this reaction product. Heat capacities 
of n-propanol, propionaldehyde, and diethyl ketone were similarly estimated. 

For the temperature range considered, the natural logarithm of 
equilibrium constants varied from 1.97 to 3.16 for reaction (1) and from 
14.9 to 21.0 for reaction (2). This would indicate the reactions must 
proceed essentially to completion before equilibrium is reached. The 
equilibrium constants increased with increasing temperature showing that 
both reaction equilibria are favored by a rise in temperature. 

The low conversions obtained in this work indicate that rate is the 
controlling factor as complete conversion would occur if the reactants 
could be activated in some way. 

4. Condition of Equipment 

Upon completion of runs reported herein, the upper reactor 
was inspected for cleanliness. Fine catalyst and carbon were deposited 
on the bottom of the screen and baffle.. The top of the screen was 
covered with a tacky carbon-like deposit. Photographs of the conditioning 
of the upper catalyst filter are shown in Plates 4 and 5. 



. 











: 1 















.. .V 




- 


' j 





r 


< .;j) •' i... , - I’ - '/ 


. ( 







39 


<% 

PLATE 4 


| 



- TOP VIEW OF UPPER CATALYST FILTER 



PLATE 5 - BOTTOM VIEW OF UPPER CATALYST FILTER 










- 40 


CONCLUSIONS 

1. Validity of Results 

Considering the two main overall reactions of the dehydrogenation 
of n-propanol, 

PrOH - 5 - PrH + H 2 

2Pr0H—DEK + CO -!- 3H 2 

the hydrogen evolved can be predicted knowing the moles propionaldehyde 
and diethyl ketone in the product. As discussed in the analytical 
methods section, the hydrogen analyses are regarded as the most reliable 
of the gaseous analyses. Calculations of predicted moles hydrogen versus 
actual moles hydrogen is given in Table IX; a plot is shown in Figure 11. 
This plot shows fair agreement with the theoretical prediction, indicating 
a reasonable accuracy of analyses. 

Material accountabilities of Runs 8 to 25 range from 93.6 to 
108.0 per cent; Runs 26 to 31 ranged from 88.0 to 108.5 per cent. Runs 
26 to 31, the dehydrogenation of propionaldehyde, were shortened to 
30 minutes which could account for the greater range of material accounta¬ 
bility experienced. 

2. Summary of Experimental Results 

1. The dehydrogenation of n-propanol in a fluidized chromia on inactive 
alumina catalyst has been studied and conversions and reaction 
efficiencies plotted for a range of reaction temperatures and 















e • 








Ci :■ i 












, i .. i.i J 

t i. \ •. w. -• 7. .. 

_ , ...... . , r 7 , 

. • . - . - : . - . .. r - 


J c i .. . j :: ,. ' . . 


1 


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41 


_j 



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<x> 


q 

m 


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rn 


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C>J 


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MOLES HYDROGEN IN OFF GAS 














42 


superficial linear gas velocities. Indications are that 
the chromia on inactive alumina catalyst used in this work is 
a less desirable dehydrogenating catalyst than reported by other 
workers. 

2. A similar dehydrogenation of propionaldehyde has been performed 
for one superficial linear gas velocity. The use of a 
propionaldehyde feed resulted in slightly improved conversions to 
diethyl ketone, however, there is evidence that the presence of 
the aldehyde tends to lower the overall activity of the catalyst. 

3. The dehydrogenation of n-propanol was shown to follow a first 
order reaction and the reaction rate was found to vary with 
temperature as indicated by the Arrhenius equation. 

4. Thermodynamic equilibrium constants have been determined at 
temperatures for the reactions considered in this study. The 
high values of equilibria constants obtained would indicate that 
the dehydrogenation of n-propanol to propionaldehyde and diethyl 
ketone is thermodynamically feasible and that the reaction warrants 
further study. 

5. The equipment used in this study functioned satisfactorily with 
adequate and sensitive control of reaction temperature over the 
superficial linear gas velocities studied. 











- 


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- 43 


BIBLIOGRAPHY 


1. Church, J. M. and H. K. Joshi., Ind.. Eng. Chem. , A3, 1804, (1951). 

2. De Q. Jones, H. K., M.Sc. Thesis, Univ, of Toronto, (1959). 

3. Gilliland, E. R. and E. A. Mason., Ind. Eng. Chem., 44, 218, (1952). 

4. Ipatieff, V. N. et al., Ind. Eng. Chem., 41., 1802, (1949). 

5. Komarewsky, V. I. and J. R. Coley., J. Am. Chem. Soc., 63 _, 700, 3269, 

(1941). 

6. Leva, M., Chemical Engineering, 289, October, (1957). 

7. Mickley, H. S. and C. A. Trilling., Ind. Eng. Chem., 41, 1135, (1949). 

8. Neish, A. C., Can. Journal of Research, 23B, 49, (1945). 

9. Tollefson, E. L., Private Communication, November, (1959). 

Warren,' G. W. et al. , Analytical Chem., 31., 1626, (1959). 


10 . 





0 


- * 


. 1 










. 









44 


APPENDICES 

A. THERMODYNAMIC STUDY OF REACTION EQUILIBRIA 

B. SAMPLE CALCULATIONS 

C. EXPERIMENTAL DATA 



- 45 


A. THERMODYNAMIC STUDY OF REACTION EQUILIBRIA 



- 46 


Thermodynamic Study of Reaction Equilibria 

For the purpose of this thermodynamic analysis of the 
dehydrogenation of n-propanol, the two following reactions were considered: 


ch 3 - ch 2 - CH 2 0H (g)^rCH 5 - CH 2 - C* (g) + h 2 (g) - (1) 

H 

2CH 3 - GH 2 - CH 2 OH (g)^Z«rCH 3 - CH 2 - C - CH 2 - CH 3 (g) 

0 

+ CO (g) + 3H 2 (g) -.— (2) 


To perform the calculations for the determination of reaction 
equilibrium constants for each reaction, it was necessary to determine the 
free energy of formation (A F )> heat of formation (AH), and specific 
heat (Gp), of the reactants and products. 

The free energy of formation of diethyl ketone was estimated using 
the emperical group contribution method of J. W. Anderson, G. H. Beyer, and 
K. M. Watson.* A similar method** was used to estimate the heat of formation 
of diethyl ketone. Specific heats of n-propanol, propionaldehyde, and 
diethyl ketone were determined using a group contribution proposed by 
Anderson, Beyer, and Watson.*** The remaining thermodynamic properties 
were obtained from Perry.**** 


* 

Reid, 

R. C., and T. K. Sherwood, "The Properties of Gases and Liquids", 
p. 129, McGraw-Hill Book Company, Inc., New York, (1958). 

kk 

Ibid. 

, p. 117. 

kkk 

Ibid. 

, p. 152. 

kkkk 

Perry 

, J. H., "Chemical Engineers 1 Handbook", 220, 238, McGraw-Hill 

Book Company, Inc., New York, (1950). 










o 


£ 










- 47 


Heats of formation and free energies of formation for reactants 
and products of the two reactions considered are shown below. 


Component 
n-propanol (g) 
propionaldehyde (g) 
diethyl ketone (g) 
carbon monoxide (g) 


Ah A F 

kcal./mole kcal./mole 

@ 25°C. 


@ 25°C. 


- 61.17 

- 49.15 
-63.0 

- 26.42 


- 38.83 

- 33.96 
-34.6 

- 32.81 


The following heat capacity expressions were used in the 
calculations: 
n-propanol 

3 ^ 2 

Cp = 4.69 + 68.32 x 10 T - 23.84 x 10 T 
propionaldehyde 

3 6 2 

Cp = 5.13 + 27.46 X 10 T - 6.61 x lo" T 
diethyl ketone 

Cp = 7.98 + 84.29 x 10 _3 T + 27.35 x IQ -6 ! 2 


carbon monoxide 


Cp = 6.60 + 1.20 x 10 T 


hydrogen 


Cp = 6.62 + 0.8 x 10 _3 T 


The equilibrium constant, Ka, was expressed as a function of 
absolute temperature using the following relationships: 


















- 48 


In Ka 

✓D T 


A H° 

RT2 


where AH? 
and, A C p 


.c 

J298 


C p dT 


- Ah 298 

= Cp (products) - Cp (reactants) 


For reaction (1), 


H 2 93 = -49.15 - (-61.17) = 12.02 kcal./mole 
A C p = 6.86 - 40.05 x 10‘ 3 T + 17.23 x 10~ 6 T 2 

RT In Ka x = 2.87 x lO'S? 2 + 6.86 In T - _ 2.02 x 10"^T + C 

where C is the constant of integration. 

To establish a value for the constant of integration, Ka x can be 

calculated at 298°K. using the free energy of formation data available 

at that temperature. 

A F° = - RT In Ka 
R 

where,A F° = F? (products) - F? (reactants) 

In the case of reaction (1), 

AFr = 33.96 - (-38.83) = 4.87 
- RT In Ka = 4.87 


This 


In Ka = -8.22 at 298°K. 
establishes the lower limit, 



In Ka>j, 

A o 

Ah t 

RT 2 


in the expression, 

dT 








. 

1 \ 




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:: I 




c - 




. 



, 


y. . . ■: > 


. ... 










k 


> 



s ...' .. ■■ ■ .: i:-j 


' - . ■ 






. 







- 49 


Finally, for reaction (1), 

R (In Ka x + 8.22) = “ 11500 


“2 6 2 
+ 6.86 In T - 2.02 x 10 T + 2.87 x 10 T 


298 


where T is the reaction temperature in °K. 


Similarly for reaction (2), 


A ^298 = 33.0 kcal./mole 
Ac p = 25.05 - 48.72 x 10 _3 T + 75.03 x 10 
R In Ka 2 = 25.05 In T - 2.42 x 10 _2 T + 1.25 x 1Q" 5 T 2 
AFr = 10.3 kcal./mole 
In Ka = -17.4 at 298°K. 


6 2 
T 


27036 

T 


r -2 -52 

R (In Ka 2 + 17.4) = I 25.05 In T - 2.42 x 10 T + 1.25 x 10 T 


27036 

T 



Equilibrium constants for reaction (1) and (2) are shown below 
for the temperatures studied for the dehydrogenation of n-propanol. 


o 

Temperature C. 

In Ka n 

In Ka ; 

375 

1.97 

14.9 

425 

2.47 

17.2 

475 

2.88 

19.2 


525 


3.16 


21.0 















c 


> 


. 









L 
















t i .1 




s 






50 


B. SAMPLE CALCULATIONS 






51 


Sample Calculations - Run 12 
1. Superficial Linear Gas Velocity 


Sup . Gas Vel. f t. 
3 

359 ft 


= feed rate 
sec. hr. 


EL. X 0.804 S22-s x 1 lb - x 1 lb - 
ml. 453 gms. 60 lb. 


mole 


Reactor Temp °R 29 .92 in. Hg 


lb. mole 
1 hr. 


3600 sec. 


492°R 

_ l _ 

Reactor Area ft^ 


x 


Reactor Pressure in. Hg 


Reactor Area = 2.175 x 10 ^ ft^ 


Sup. Gas Vel. ft. _ £ ee( j rate ml s. Reactor Temp °R 

sec. hr. Reactor Press, in Hg. 

Run 12 - Reactor Temp. = 425°C. = 1257°R. 

Reactor Press. = 3.0 +27.5 = 30.5 in. Hg. 

Feed Rate = 620 mis./hr. 


x 8.25 x 10 


-6 


Sup. Gas Vel. ft. = mis. x 1257 .. R x 8-25 x 10 

hr. 30.5 in.Hg. 


-6 


sec, 


= 0.209 ft. 

sec. 


2. Material Accountability - Run 12 

Vol. of n-Propanol Fed = 620 mis. 

O 

Vol. Off Gas = 2.35 ft @ 70°F, 1 atm. 
Wt. Liquid Product = 446 gms. 


Analysis of Gas: 

h 2 

= 46.7 

(Volume or 

CO 

= 2.0 

mole 7o) 

C0 2 

= 4.5 


c 3 

= 38.7 


PrH 

= 1.1 


n-PrOH 

= 1.9 


Unknown 

= 5.0 






















! , 




" V 


<L'. 


. 


; c 


c. . 





■ ■ ■ i \ 


V 








3 


L 





52 


Volume of Off Gas at S.T.P. 


492 27.5 

X 530 X 29.9 


2.01 ft . 



= 2.01 ft" 3 

x 28.32 

litres = 56.9 litres 

f t 3 


Moles of gas 

= 56.9 _ 
22.4 

2.54 gm-moles. 

Component 

Mole 7 0 

Moles 

M.Wt. Weight (gm; 

h 2 

46.7 

1.19 

2 2.4 

CO 

2.0 

0.05 

28 1.4 

co 2 

4.5 

0.11 

44 4.8 

C 3~ 

38.7 

0.98 

42 41-.1 

PrH 

1.1 

0.03 

58 1.7 

n-PrOH 

1.9 

0.05 

60 3.0 

Unknown 

5.0 

0.13 

40* 5.1 

59.5 


* Note: 

Assumed 

Molecular Weight 


Total Wt. 

of Products = 59.5 + 446 = 505.5 ; 


Wt. of Feed = 620 

mis. x 0.80 x = 498 ; 


7 , Material Accountability 


— Pr g' is - - - x 100 
Wt. Feed 


505.5 (100 ) 

498 


= 101.5 7 . 















C . «1 t. : 








53 


C. EXPERIMENTAL DATA 




54 


TABLE I 

ANALYSES OF LIQUID PRODUCTS (WEIGHT %) 

DEHYDROGENATION OF n-PROPANOL AND PROPIONALDEHYDE WITH A FLUIDIZED 
CHROMIC OXIDE ON INACTIVE ALUMINA CATALYST 


Run No. 


Pentene PrH n-PrOH DEK Other 


n-Propanol Feed 


8 


33.5 

50.3 

9 .40 

6.6 

9 

•JU 

A 

53.2 

20.6 

10.90 

5.3 

10 

* 

52.9 

19.6 

12.30 

15.2 

11 

0.50 

6.8 

83.6 

0.70 

8.5 

12 

0.67 

18.0 

70.0 

2.35 

8.0 

13 

1.12 

32.9 

55.8 

2.50 

7.6 

14 

0.85 

59.9 

19.8 

10.00 

9.5 

15 

0.34 

3.9 

90.2 

0.80 

4.8 

16 

0.78 

12.3 

79.2 

. 1.84 

5.9 

17 

0.26 

4.4 

89.7 

0.65 

5.0 

18 

0.71 

14.9 

77.9 

2.12 

4.4 

19 

0.71 

53.4 

31.9 

6.70 

7.6 

20 

0.83 

34.9 

55.9 

3.10 

5.6 

21 

0.85 

32.1 

57.4 

3.50 

6.3 

22 

0.70 

56.5 

27.1 

8.00 

7.7 

24 

1.05 

19.6 

62.0 

4.10 

13.1 

25 

0.60 

37.6 

42.5 

8.50 

11.0 


Propionaldehyde Feed 




26 

84.0 

0.70 

15.3 

27 

83.7 

1.20 

15.1 

28 

75.0 

3.60 

21.4 

29 

59.5 

11.00 

29 .2 

30 

86.6 

0.40 

13.0 

31 

83.8 

0.80 

15.4 

PrH Feed Stock 

88.2 


11.8 


* Not determined 









;."ju j. ' . 




■ ■ ■ i 


■/....: r 


... ( 












J 

r 






L 















55 


TABLE II 

ANALYSES OF GASEOUS PRODUCTS (VOLUME %) 

DEHYDROGENATION OF n-PROPANOL AND PRO PIONALDEHYDE WITH A FLUIDIZED 
CHROMIC OXIDE ON INACTIVE ALUMINA CATALYST 


Run No. 

H2 

CO 

COp 

C 3 

PrH 

n-PrOH 

Unknown 

n-Propanol Feed 







11 

59.0 

0.5 

2.3 

31.9 

0.5 

0.7 

6.2 

12 

46.7 

2.0 

4.5 

38.7 

1.1 

1.9 

5.0 

13 

37.8 

2.7 

6.3 

44.5 

1.5 

2.8 

4.4 

14 

44.0 

3.0 

6.9 

37.6 

1.3 

3.1 

4.1 

15 

70.0 

0.6 

1.7 

21.7 

0.3 

0.7 

5.0 

16 

57.2 

1.5 

2.9 

31.4 

0.7 

1.5 

4.8 

17 

70.0 

0.8 

2.0 

21.0 

0.4 

1.4 

4.5 

18 

58.2 

1.8 

3.4 

30.6 

0.8 

1.9 

3.2 

19 

43.3 

3.0 

8.4 

37.7 

1.2 

2.5 

3.9 

20 

54.3 

3.3 

5.4 

31.8 

1.0 

2.2 

2.0 

21 

43.5 

3.6 

6.9 

39.4 

1.3 

2.9 

2.5 

22 

50.5 

3.5 

7.6 

31.6 

1.0 

3.3 

2.5 

24 

61.5 

3.1 

3.7 

27.0 

0.8 

1.6 

2.3 

25 

53.5 

4.0 . 

5.3 

31.5 

1.1 

2.8 

1.8 


Propionaldehyde Feed 


26 

36.0 

25.0 

28.8 

5.1 

1.9 

3.3 

27 

33 ..5 

35.0 

21.2 

5.4 

1.6 

3.4 

28 

32.5 

49.0 

* 


* 

n 

29 

32.5 

46.0 

12.5 

3.3 

1.0 

4.7 

30 

35.0 

25.0 

32.9 

4.0 

2.7 

2.8 

31 

34.0 

34.0 

22.2 

3.9 

0.4 

5 .5 


Not determined 


















56 


TABLE III 

OPERATING CONDITIONS AND MATERIAL ACCOUNTABILITIES 

DEHYDROGENATION OF n-PROPANOL WITH A FLUIDIZED CHROMIC OXIDE 
ON INACTIVE ALUMINA CATALYST 


Wt. of Material 


Run No. 

Reactor 

Temp 

°C 

Feed 
Rate 
mis./hr. 

Reactor 

Press 

in.Hg. 

Lin. Gas 
Velocity 
ft./sec. 

Vol. of 
Off Gas 
ft 3 @ NTP 

Liquid 
Prods. 

gms. 

Account' 

ability 

7 

/o 

8 

475 

587 

2.75 

0.212 

4.72 

350 


9 

525 

590 

3.50 

0.226 

8.77 

271 

* 

10 

554 

520 

3.50 

0.206 

9.85 

203 


11 

375 

680 

3.00 

0.212 

0.76 

529 

99.6 

12 

425 

620 

3.00 

0.209 

2.35 

446 

101.5 

13 

475 

573 

3.25 

0.205 

4.19 

357 

105.0 

14 

525 

500 

3.50 

0.190 

6.90 

188 

93.6 

15 

375 

1030 

3.25 

0.327 

0.72 

819 

101.0 

16 

425 

875 

3.40 

0.293 

2.15 

663 

100.8 

17 

375 

1300 

3.85 

0.398 

1.11 

1023 

99 .4 

18 

425 

1190 

4.40 

0.386 

3.29 

901 

101.5 

19 

525 

1025 

5.75 

0.362 

13.40 

521 

108.0 

20 

475 

1135 

5.15 

0.386 

7.95 

742 

101.1 

21 

475 

855 

4.50 

0.296 

6.47 

549 

106.0 

22 

525 

.820 

5.25 

0.296 

11.10 

374 

99.5 

24 

425 

550 

3.50 

0.184 

2.10 

398 

99.1 

25 

475 

537 

3.75 

0.191 

4.83 

317 

99.1 


* Gas analyses not determined 























57 


TABLE IV 

OPERATING CONDITIONS AND MATERIAL ACCOUNTABILITIES 

DEHYDROGENATION OF PROPIONALDEHYDE WITH A FLUIDIZED CHROMIC OXIDE 

ON INACTIVE ALUMINA CATALYST 


Run No. 

Reactor 
Temp . 

°C 

Feed 

Rate 
mis./hr. 

Reactor 

Press. 
in.Hg. 

26 

375 

584 

3.25 

27 

425 

544 

3.25 

28 

475 

515 

3.50 

29 

525 

447 

4.00 

30 

375 

580 

■3.50 

31 

425 

536 

3.50 


Lin. Gas 
Velocity 
ft. / sec. 

Vol. of 
Off Gas 
ft 3 (a NTP 

Wt. of 
Liquid 
Prods. 

gms . 

Material 

Account¬ 

ability 

% 

0.190 

0.205 

407 

88.0 

0.190 

0.348 

408 

95.6 

0.191 

1.435 

366 

99 .5 

0.175 

3.920 

218 

93.1 

0.187 

0.154 

456 

108.5 

0.186 

0.328 

393 

93.1 









: 'iT.ilM 





w i 



c 








CALCULATIONS OF CONVERSIONS AND REACTION EFFICIENCIES 


58 




d 




















o 




















•H 




















CO 

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M3 



M0 

m 

t—1 

m 


MO 

CTN 

m 

in 

O 


in 

m 

H 

Ed 

Pi 


















c n 

p 

CD S'? 



o 

CO 


CO 

00 

cn 

CM 

CM 


MO 

MO 

1-1 

o 

00 

oo 

>p 

CP 

> 

m 

M3 

1^- 

MO 

m 

in 

nO 

MO 

m 

MO 


m 


m 

NO 

m 

m 



d 
















<3 


o 


















H 


o 


















<3 




















u 




















<3 

ti 



















is 

o 



















H 

•H 




















4-J 

o 


















E3 

o 

d 



















d 

CD 

i—1 

00 

CM 

Mt 

on 

00 

CM 

i—1 

MO 


m 


in 

cn 

in 

m 

t-'- 

<i 

0) 

•H S'? 



















Pi 

CD 

CM 

ON 

ON 

in 




o 

CON 

r- 

o 


NO 



i—1 

CM 

w 


•H 

1-1 







i—1 



i—1 







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MP 


















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w 

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CD 


















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a 


















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CD 


















w 

cd 

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<r 

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m 

m 

on 

00 

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m 

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m 

m 

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M 

Pi 

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l-1 

m 

CON 

nO 


MO 

l—1 

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m 

cn 

cn 

ON 

ON 

i—1 

i—i 

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MP 


CO 

CM 

cn 


<fr 

cn 

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in 

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CD 


















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s 




















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d 


















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rd 

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M3 

CM 

in 

00- <t 

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cn 

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m 

o 

NO 

CM 

NO 

o 

On 

Q 

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p 


















W 

Pi 

CD g-S 

CM 

CO 

o 

oo 

r^. 

MO 

o 

o 

in 

CM 

MO 

o 


<1- 

<!■ 


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CM 

CP 

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CM 

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m 

m 

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NO 

M 

1 

d 


















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d 

o 


















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TO 


















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CD 




















Ed -lj 


















EC 

CA 

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on 

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i—i 

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59 


TABLE VI 

CALCULATION OF CONVERSIONS AND REACTION EFFICIENCIES 

DEHYDROGENATION OF PROPIONALDEHYDE WITH A FLUIDIZED CHROMIC OXIDE 

ON INACTIVE ALUMINA CATALYST 


Liquid Product (Moles) 
Run No. PrH DEK 


Moles Moles 
PrH PrH 
Fed* Converted 


PrH 

Conversion 

7 . 


DEK 

Efficiency 

7 

_ fo _ 


26 

5.90 

0.032 

7.15 

1.25 

17.5 

5.1 

27 

5.90 

0.057 

6.66 

0.76 

11.4 

15.0 

28 

4.75 

0.154 

6.31 

1.56 

24.8 

19.7 

29 

2.24 

0.279 

5.48 

3.24 

59.1 

17 .2 

30 

6.81 

0.021 

7.12 

0.41 

5.8 

10.2 

31 

5.87 

0.037 

6.59 

0.92 

14.0 

7.8 


* Based on fraction of propionaldehyde in feed 














TV . 


, ' L' 






:r ' 



■ } 


. ; O' .; 




; f! 


I - :* 





.1 












60 


TABLE VII 


CALCULATIONS OF LOG CONCENTRATION OF UNCHANGED n-PROPANOL 

AND TIME OF REACTION 


DEHYDROGENATION OF n-PROPANOL WITH A FLUIDIZED CHROMIC OXIDE 
ON INACTIVE ALUMINA CATALYST 


Run No. 

Reactor 
Temp. 

°C 

Time of 
Reaction 

secs. 

Moles 

n-PrOH 

fed 

Moles 
n-PrOH 
in Prod . 

Fraction 

Unchanged 

C 

Log 10 C 

11 

375 

14.15 

9.10 

7.37 

0.812 

1.910 

15 

375 

9.18 

13.80 

12.29 

0.890 

1.948 

17 

375 

7.54 

17.42 

15.33 

O'. 880 • 

1.944 

12 

425 

14.35 

8.31 ' 

5.20 

0.626 

1.796 

16 

425 

10.25 

11.71 

8.75 

0.746 

1.872 

18 

425 

7.77 

15.92 

11.70 

0.734 

1.865 

24 

425 

16.30 

7.37 

4.12 

0,560 

1.748 

8 

475 

14.15 

7.87 

2.94 

0.374 

1.572 

13 

475 

14.60 

7.67 

3.32 

0.433 

1.636 

20 

475 

7.77 

15.21 

6.90 

0.453 

1.654 

21 

475 

10.10 

11.45 

5.25 

0.459 

1.661 

25 

475 

15.70 

7.20 

2.25 

0.312 

1.494 

9 

525 

13.30 

7.92 

0.93 

0.117 

1.068 

14 

525 

15.80 

6.70 

0.62 

0.093 

2.966 

19 

525 

8.30 

13.75 

2.76 

0.200 

1.300 

22 

525 

10.10 

11.00 

1.70 

0.155 

1.189 















61 


TABLE VIII 

CALCULATIONS OF VARIATION OF THE RATE OF DEHYDROGENATION OF n-PROPANOL 

WITH TEMPERATURE 

DEHYDROGENATION OF n-PROPANOL WITH A FLUIDIZED CHROMIC OXIDE 
ON INACTIVE ALUMINA CATALYST 


Run No. 

Fraction 

Unchanged 

C 

Time of 

Reaction 

secs . 

Reaction Rate 

Constant 

k 

A x 103 

Logio 

11 

0.812 

14.15 

0.0146 

1.545 

2.164 

15 

0.890 

9.18 

0.0129 

1.545 

2.110 

17 

0.880 

7 .54 

0.0169 

1.545 

2.227 

12 

0.626 

14.35 

0.0325 

1.430 

2.512 

16 

0.746 

10.25 

0.0285 

1.430 

2.454 

18 

0.734 

7.77 

0.0395 

1.430 

2.596 

24 

0.560 

16.30 

0.0356 

1.430 

2.550 

8 

0.374 

14.15 

0.0700 

1.350 

2.846 

13 

0.433 

14.60 

0.0575 

1.350 

2.759 

20 

0.453 

7.77 

0.1020 

1.350 

1.008 

21 

0.459 

10.10 

0.0772 

1.350 

2.887 

25 

0.312 

15.70 

0.0740 

1.350 

2.868 

9 

0.117 

13.30 

0.1600 

1.250 

1.206 

14 

0.093 

15.80 

0.1510 

1.250 

1.178 

19 

0.200 

8.30 

0.1940 

1.250 

1.288 

22 

0.155 

10.10 

0.1850 

1.250 

1.266 
































62 


TABLE IX 

CALCULATION OF PREDICTED MOLES HYDROGEN AND ACTUAL MOLES HYDROGEN EVOLVED 

DEHYDROGENATION OF n-PROPANOL WITH A FLUIDIZED CHROMIC OXIDE 
ON INACTIVE ALUMINA CATALYST 


Run No. 

Liquid 

Prll 

moles 

Product 

DEK 

moles 

Moles PrH 
-f 

3(moles DEK) 

Per Cent 

Il 2 in Off 
Gas 

Vol. of 
Off Gas 
ft 3 

H 2 in 
Off Gas 
moles 

11 

0.62 

0.046 

0.75 

59.0 

0.76 

0.44 

12 

1.39 

0.122 

1.75 

46.7 

2.35 

1.32 

13 

2.03 

0.104 

2.34 

37.8 

4.19 

1.90 

14 

1.94 

0.219 

2.60 

44.0 

6.90 

3.65 

15 

0.55 

0.076 

0.78 

70.0 

0.72 

0.60 

16 

1.41 

0.142 

1.83 

57.2 

2.15 

1.48 

17 

0.78 

0.078 

1.01 

70.0 

1.11 

0.89 

18 

2.33 

0.222 

3.00 

58.2 

3.29 

2.30 

19 

4.79 

0.405 

6.01 

43.3 

13.40 

6.95 

20 

4.46 

0.268 

5.26 

54.3 

7.95 

5.17 

21 

3.04 

0.224 

3.71 

43.5 

6.47 

3.38 

22 

3.64 

0.348 

4.69 

50.5 

11.10 

6.71 

24 

1.35 

0.188 

1.91 

61.5 

2.10 

1.55 

25 

2.05 

0.314 

2.99 

53.5 

4.83 

3.10 


















































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