Effect of hydrogen pressure on the rate of the heterogeneous catalytic isomerization of cyclohexane Communication I. Kinetics of the isomerization of cyclohexane over a tungsten sulfide catalyst

Abstract

1. Isomerization of cyclohexane into methylcyclopentane in the presence of tungsten sulfide was studied at the temperature range of 320–430° in a flow system under hydrogen pressure. 2. At constant rates of feed of cyclohexane and hydrogen, an increase of total pressure from 50 to 250 atm at 320° and 340° leads to a decrease of the degree of isomerization; at 370° the yields of the reaction products are changed insignificantly by increased pressure, while they rise sharply with pressure at 400° and 430°. 3. The kinetic order of the reaction in respect to cyclohexane is equal to 0.4 over the temperature range studied by us. 4. The reaction rate constant does not depend on partial pressure of hydrogen at 430°. Thus, the observed increase of the degree of isomerization with elevation of total pressure at this temperature is caused by an increased time of contact. 5. The logarithm of the reaction rate constant decreases at 340° in a linear manner with increasing partial pressure of hydrogen.