Influencing factors of CO2 and H2 utilization rate in CO2 hydrogenation to methanol and process optimization design
The utilization rate of CO2 and H2 raw materials is an important factor affecting the process economy of CO2 hydrogenation to methanol.The influences of catalyst type,temperature,pressure,space velocity and H2/CO2 feed ratio on CO2 conversion and methanol selectivity,and the influences of process conditions on the loss of carbon and hydrogen in gas and liquid phase were discussed,respectively.A cycle process for CO2 hydrogenation to methanol was proposed by introducing the stripping unit to recover the dissolved CO2 from liquid phase.The effects of purge gas on carbon and hydrogen utilization and process economy were studied to determine the optimal rate of purge gas.The results showed that the loss of dissolved CO2 was negligible after stripping separation and the loss of carbon and hydrogen mainly depended on the purge gas.The equipment investment cost decreased gradually with the increase of the purge gas flowrate while the unit production cost firstly decreased and then increased.The utilization rate of CO2 and H2 were respectively 98.9%and 65.9%when the flow rate ratio of purge to feed was set as 1%.Compared with the traditional process,the proposed process had an effective utilization of raw materials.This study provides a feasible path for efficient conversion of CO2 hydrogenation to methanol.