High CO conversion in syngas to aromatics by addition of ZnMnZr oxides as methanol synthesis components

Abstract

In oxide-zeolite (OX-ZEO) strategy, it was hard to achieve both higher CO conversion and aromatics selectivity. In this paper, methanol synthesis component xZn2Mn8Zr were prepared. With increasing Zn content, CO conversion over ternary oxides increased without remarkable decrease in the sum of selectivity of methanol and dimethyl ester (DME). 2Zn2Mn8Zr (molar ratio) is then coupled with either SAPO-34 or H-ZSM-5 for syngas conversion. Combined with the result of thermogravimetric analysis, bifunctional catalyst with more residual hydrocarbon pool species (HCPs) could achieve higher selectivity of unsaturated organic-products. Loss of HCPs should be attributed to over-hydrogenation. The over-hydrogenation could be relevant with either Zn concentration or close contact of 2Zn2Mn8Zr with H-ZSM-5. To alleviate such over-hydrogenation, ZnMnZr pellet with lower Zn concentration were mixed with the pellet of 6Mn4Zr/H-ZSM-5 by granule mixing method. The multi-functional catalyst exhibited much higher activity in STA, especially at high space velocity. The CO conversion over multi-functional catalyst could reach 43% at 600 mL·gcat-1·h-1 with aromatics selectivity around 72%, and was stable during 100 h reaction.