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The influence of capillary condensation of reagents in porous catalysts for hydrodesulfurization at temperatures below 195°C and at pressures around 0.95 MPa was investigated experimentally and by modelling. The rate of reaction of thiophene in a solution of n‐heptane was studied in steady and dynamic modes over two Ni‐Mo/γ‐Al2O3 mesoporous catalysts with mean pore diameters differing by 2.6‐fold. Pronounced rate hysteresis was observed under thermal cycling for the narrow‐pore catalyst, but less so for the wide‐pore catalyst. The process was modelled for a mixed‐flow reactor under steady and dynamic conditions by means of the Kelvin equation and introducing two kinetic models for liquid and vapour phase to estimate the concentration of reactant in both phases. The model exhibited good agreement with hysteresis results.

Catalytic reductive methylation of acetylhydrazine (AH) to dimethyl acetylhydrazine (DMAH) is a key step in the production of unsymmetrical dimethyl hydrazine (UDMH). The results of the present study show that the limiting step in this process is the hydrogenation of AH to mono methyl acetylhydrazine (MMAH). The kinetics of the hydrogenation of acetylhydrazone (AOH) using an activated carbon catalyst impregnated with 5 % palladium were studied in a stirred slurry reactor at 40±65 C and 5±25 bar hydrogen pressure. Analysis of the data from this investigation indicates that the rate of hydrogenation is consistent with an Eley-Rideal reaction mechanism. The activation energy for the hydrogenation was determined as 44 kJ/mol.