Selective hydrogenation of acetylene through a short contact time reactor

摘要

A novel approach to the selective hydrogenation of acetylene involves a short contact time rector.A thin Pd/#gamma#-Al_2O_3 catalytic membrane (about 5 #mu#m thick) was observed to be void of minor defects.Forcing a dilute C_2H_2/H_2/Ar mixture through the layer produced high conversions coupled with high selectivity at high temperatures.The selectivity was observed to increase with temperature.A gas-dispersion model with derived kinetics was employed to explain the results.A solution to the corresponding coupled nonlinear differential equations resulted in a Peclet number of 64.5 and a contact time of 9.5 X 10~(-3) s through the reactor at 100 deg C.A critical thickness is predicted to exist for a maximum in ethylene concentration.A critical thickness is predicted to exist for a maximum in ethylene concentration.A value of 2.5#mu#m at 200 deg C is representative.Lastly,permeability experiments agree with modeling results to show that Knudsen diffusio is absent despite a narrow pore-size distribution.