Indium modified zirconia coupling with HZSM-5 for syngas conversion to aromatics

Abstract

Metal oxide-zeolite (OX-ZEO) bifunctional catalysts have been shown to have excellent aromatic selectivity and catalytic stability in syngas conversion; however, low CO conversion hinders their further development. In this paper, a series of In-ZrO2 bi-metallic oxides with In/Zr molar ratio ranging of 1/100−1/1 were prepared. After thoroughly investigated by X-ray diffraction, transmission electron microscopy, N2 sorption, pyridine-adsorbed infrared spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance and temperature programmed desorption technologies, we found that introduction of indium has significantly influence on the catalytic performance due to the variation of sample's physicochemical properties. Indium species was benefit to the dissociation of H2 that promotes CO activation. Nevertheless, it also induced the formation of more CH4. In-ZrO2 oxide with In/Zr ratio of 1/50 showed CO conversion of 18.2% with the selectivity of oxygenates of 86.4%. After combined with H-ZSM-5, In/Zr=1/50&H-ZSM-5 gave CO conversion of 46.5% with C5+ selectivity of 62.6% and the aromatic selectivity in C5+ reached 93.4%. However, the catalytic stability of this bifunctional catalyst was gradually decreased due to the aggregation of indium atoms.