(703g) A Comparative Investigation of CO2 Removal In Two Different Hydrogen Redistribution Strategies for a Two-Stage Hydrogen-Permselective Membrane Methanol Reactor

One of the major problems facing mankind in 21^st century is the global warming which is induced by the increasing concentration of carbon dioxide (CO₂) and other greenhouse gases in the atmosphere. One of the most promising processes for controlling the atmospheric CO₂ level is conversion of CO₂ to methanol by catalytic hydrogenation. In this paper, two different hydrogen redistribution strategies on CO₂ removal rate along a two-stage hydrogen-permselective membrane reactor have been compared. In the first strategy (co-current mode), fresh synthesis gas flows in the tube side of the second stage in same direction with reacting gas stream in the shell side, so that more hydrogen is provided in the first sections of the reactor. In the second strategy (counter-current mode), the gas streams are in the opposite direction, so that more hydrogen is provided in the last sections of the reactor. For this system, a dynamic plug flow one-dimensional model in the presence of catalyst deactivation was employed to compare both strategies in terms of activity, temperature, CO₂ removal and water production. It was recognized that the reactor in counter-current mode has great potential to higher conversion of CO₂ whereas in co-current mode, profile of temperature is more favorable and water production is lower. Enhancement of the CO₂ removal in counter-current mode causes a lower environmental impact. The lower water production rate in co-current mode reduces catalyst recrystallization.