A comparative investigation of CO2 removal in two different hydrogen redistribution strategies for a two-stage hydrogen-permselective Cu/ZnO catalytic membrane methanol reactor

The catalytic hydrogenation of CO2 to methanol is regarded as the effective and reliable method to reduce the concentration of this pollutant in the atmosphere. 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, sothat more hydrogen is provided in the first sections of the reactor. In the second strategy (countercurrentmode), 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 countercurrent 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 cocurrent mode reduces catalyst recrystallization.

کلیدواژه ها:

Greenhouse gases ، CO2 removal ، Two-stage membrane reactor ، Hydrogen-permselective membrane ، Cocurrent ، Counter-current