HYDROGENATION OF CARBON-DIOXIDE OVER CU-ZN-CHROMATE ZEOLITE COMPOSITECATALYST - THE EFFECTS OF REACTION BEHAVIOR OF ALKENES ON HYDROCARBONSYNTHESIS/

The hydrogenation of carbon dioxide was studied using composite cataly sts comprised of Cu-Zn-chromate and HY zeolite, These composite cataly sts enabled the reaction combining methanol synthesis and methanol-to- gasoline reaction, and achieved the formation of ethylene and propene as the first example of the composite catalysts. The addition of alkal ine metals, especially cesium, to Cu-Zn-chromate enhanced the selectiv ities of those alkenes. The influences of the reaction pressure and th e space velocity on the production of alkenes show that alkanes are ob tained by the hydrogenation of the corresponding alkenes, The composit e catalysts producing alkenes in high selectivity afforded heavier hyd rocarbons preferentially, These results indicate that the hydrogenatio n of alkenes inhibits the carbon homologation of alkenes to result in the predominant formation of the corresponding lighter alkanes. From t hese observations, it was found that methanol synthesis catalysts used for the composite catalysts are required to be effective for methanol synthesis at high temperature (over 300 degrees C) and to bear the lo w activity of the hydrogenation of alkenes.