Hydrocarbon synthesis through CO₂ hydrogenation over CuZnOZrO₂/zeolite hybrid catalysts

Direct syntheses of hydrocarbons from CO₂ hydrogenation were investigated over hybrid catalysts consisting of methanol synthesis catalyst (CuZnOZrO₂) and zeolites (MFI and SAPO). The yield of hydrocarbons was strongly depending upon the amount of zeolite's acid sites as measured by NH₃ TPD, while the product distributions were hardly affected by the change of acidity. The main product was ethane in the case of MFI hybrid catalyst and C₃ or C₄ hydrocarbon in the case of SAPO hybrid catalyst. This difference in product distribution was attributed to different mechanism of hydrocarbon formation. Investigation based on the ethene co-reaction suggested that the consecutive mechanism operated for HZSM-5 and the carbon pool mechanism for SAPO.