A facile approach for fabricating highly active ZrCeZnOx in combination with SAPO-34 for the conversion of syngas into light olefins

Abstract

The metal oxide plays an important role for transformation of syngas into light olefins over bifunctional catalysts (i.e., metal oxide and zeolite), since the adsorption and activation of CO and H2 occur on metal oxide surface. In this study, the ZrCeZnOx nanoparticles metal oxides were prepared by the coprecipitation method, the varied concertation of surface oxygen vacancies were formed by pretreating ZrCeZnOx in different atmospheres, viz., air, argon and hydrogen. The results show that the air- and argon-pretreated ZrCeZnOx exhibited similar structure and generated the Ce0.5Zr0.5O2 solid solution. While for the H2-pretreated one, a high surface oxygen vacancy concentration (24.3%) was obtained, and the CeO2 migrates out from the Ce0.5Zr0.5O2 solid solution. The temperature programmed desorption of CO results show that the migrated CeO2 does not benefit the CO adsorption. Instead, both the air- and argon-pretreated ZrCeZnOx exhibited large amount of CO chemisorption at ~410 °C (close to the reaction temperature 400 °C), which hereby significantly affects the catalytic activity of bifunctional catalyst ZrCeZnOx/SAPO-34. These results were different from the previous reported results, and will contribute to the design and pretreatment of metal oxide in bifunctional catalyst for syngas conversion into light olefins.