Ethanol conversion into 1,3-butadiene over Zn-Zr mixed oxide catalysts supported on ordered mesoporous materials

Abstract

In order to increase 1,3-BD yield, ordered mesoporous materials (OMMs) was synthesized and used as supporting materials of heterogeneous catalysts for ethanol conversion into 1,3-BD. To make acidic and basic sites acting as active sites on the surface of catalysts, a moderate (5 wt%) amount of zinc oxide (ZnO) and zirconium oxide (ZrO2) were impregnated on as-prepared various supporting materials at a time. Prepared catalysts showed different acid-base properties according to used supporting materials. The ordered mesoporous silicas (OMSs) based catalysts were proven to exhibit higher ethanol conversions and 1,3-BD selectivities because they have not only adequate number and strength of acidic sites and basic sites but also very regular mesoporous structure. Especially ZnO-ZrO2/KIT-6 revealed a higher 1,3-BD selectivity above 54.0% at ethanol conversion of 82.5% at 400 degrees C. On the other hand, the selectivity of diethylether (DEE) was grown to over 68% in the case of ordered mesoporous alumina (OMA) based catalyst for example ZnO-ZrO2/OMA catalyst with a higher ethanol conversion above 80% at the same temperature. A similar type of catalyst with the ZnO-ZrO2/KIT-6, ZnO-ZrO2/aSiO(2) exhibited relatively low ethanol conversion and selectivity toward 1,3-BD. Through these results, it was confirmed that adequate number and strength of strong acidic and basic sites are key factors for full conversion of ethanol to 1,3-BD with well-developed ordered mesoporous structure.