Thermal Decomposition of Acetaldehyde in the Presence of Hydrogen Sulfide. II. Effects of Chain-inhibitors

Abstract

Abstract The effect of propylene, isobutylene and nitric oxide as inhibitors on the thermal decomposition of acetaldehyde in the presence of hydrogen sulfide has been investigated over the temperature range of 380 to 494°C. Of the three inhibitors, which are all effective in reducing the rate of decomposition, isobutylene is slightly more efficient than propylene, and nitric oxide is far more efficient than the other two. With propylene and isobutylene, the rate of decomposition is reduced with the increasing amount of the inhibitor until a constant rate is reached, while with nitric oxide the rate passes through a minimum value and then increases again in proportion to the pressure of the inhibitor. The residual rate of the maximally inhibited decomposition is almost the same for the three inhibitors and is represented by –d[CH3CHO]/dt=ki[H2S] [CH3·CHO]. A comparison of the above results with those of the decomposition in the absence of an inhibitor suggests that the residual decomposition remaining after being fully in-hibited is a molecular process catalyzed by hydrogen sulfide.