Document Type

Thesis

Date of Award

9-30-1987

Degree Name

Master of Science in Chemical Engineering - (M.S.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Joseph W. Bozzelli

Second Advisor

Charles M. Tsai

Third Advisor

Chen-Chong Lin

Abstract

The reactions of methylene chloride and carbon tetrachloride in hydrogen in the temperature range 500 - 1000° C were studied using tubular flow reactors of three diameters. (ID: 0.40, 1.05, 1.60 cm). Residence time range was from 0.3 to 3.5 seconds. Temperature profiles of the reactors was kept within +/- 5° C of central 85% for the 18 inch long reactor, at a total pressure of 1 atmosphere. No chlorinated hydrocarbon products were observed at or above 950° C. The major products in this temperature range were CH4, C2H2, C2H4, C2H6 and HCl.

The pseudo first order plug flow model is used for analysis of the experimental data, the kinetic parameters and product distribution were experimentally determined for each size reactor. The wall and bulk reaction rate constants were decoupled via analysis of data from three different surface to volume reactors. The results show that the increase in the surface to volume ratio of the reactor tube, increases the decomposition of reactants. The following global rate equations are found to fit the data:

a> Carbon tetrachloride in H2:

kb= 7.26*107 EXP(-31,000/RT) (l/sec), gas phase

kw= 9.77*108 EXP(-39,400/RT) (cm/sec) at the wall

k values obtained under following conditions:

ratio of s/v : 2.5 to 10

H2 : 1 Atm

H2 / CCl4 ratio : 14 :: 1

Temperatures : 500° C to 600° C

b> Methylene Chloride in H2:

kb= 2.84*1010 EXP(-50,000/RT) (l/sec), gas phase

kw= 2.65*1010 EXP(-57,800/RT) (cm/sec) at the wall

k values obtained under following conditions:

ratio of s/v : 2.5 to 10

H2 : 1 Atm

H2/CH2Cl2 ratio : 4 :: 1

Temperatures : 700° C to 800° C

In addition to the kinetics study and product distribution, detailed mechanistic computer modelling of our reaction is also done, the results show good comparison to the experimental results with some difference between observed and calculated major products (HCl, CHCl3) and the reactant (CCl4).

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