CATALYTIC COMBUSTION OF PROPANE IN A MEMBRANE REACTOR WITH SEPARATE FEED OF REACTANTS .2. OPERATION IN PRESENCE OF TRANS-MEMBRANE PRESSURE-GRADIENTS

This is the second communication of a series dealing with an experimental and modelling study on propane catalytic combustion in a membrane reactor with separate feed of reactants. In paper I the behaviour of the reactor in the absence of trans-membrane pressure gradients was presented and discussed. Attention is here focused on the reactor behaviour when pressure differences are applied over the membrane, resulting in a convective flow through the membrane itself. By these means, a major conversion enhancement (up to more than 300%) is achievable compared to the case in which only diffusive mass transfer controls the reactor performance. However, above certain pressure differences (> 1 bar), this is obtained at the price of noticeable slip of unconverted reactants across the membrane. The experimental results are in good agreement with the predictions of an isothermal model based on the numerical solution of differential mass balances across the membrane, employing a Stefan-Maxwell expression for diffusive fluxes and a d'Arcy law for convective ones

A comprehensive study of deep catalytic oxidation of benzene, toluene, ethyl acetate, and their mixtures over Pd/ZSM-5 catalyst: Mutual effects and kinetics

Reaction behaviors and kinetics of catalytic oxidation of benzene, toluene, and ethyl acetate with feed concentrations in the range of 700-5,000 ppm over Pd/ZSM-5 catalyst were investigated. Results for single components show that ethyl acetate (T (50) = 190-200A degrees C) is more easily oxidized than benzene (T (50) = 215-225A degrees C) and toluene (T (50) = 225-235A degrees C). The conversion of ethyl acetate was increased with the increase of its feeding concentration, while the opposite behaviors were observed for benzene and toluene as their conversion rates were decreased with the increase of the inlet concentration. Different behaviors were observed in catalytic oxidation of volatile organic compound (VOC) multi-components, the presence of benzene or toluene inhibits the conversion of ethyl acetate, and the aromatic hydrocarbons inhibit each other in all cases. Ethyl acetate possesses obvious inhibitory effect on benzene oxidation, while it is interesting to note that ethyl acetate has a promotion effect on toluene conversion. The kinetic data were fitted by the Power-law and Mars-van Krevelen kinetic models. The fitting result shows that the Power-law model is more suitable for predicting the conversion of benzene than the other VOCs, and the Mars-van Krevelen model can accurately express the reaction rate of all investigated VOCs