【摘 要】
：
The effects of crystallite size on the physicochemical properties and surface defects of pure monoclinic ZrO2 catalysts for isobutene synthesis were studied.We prepared a series of monoclinic ZrO2 catalysts with different crystallite size by changing calc
【机 构】
：
State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiy
论文部分内容阅读
The effects of crystallite size on the physicochemical properties and surface defects of pure monoclinic ZrO2 catalysts for isobutene synthesis were studied.We prepared a series of monoclinic ZrO2 catalysts with different crystallite size by changing calcination temperature and evaluated their catalytic perfor-mance for isobutene synthesis from syngas.ZrO2 with small crystalline size showed higher CO conversion and isobutene selectivity,while samples with large crystalline size preferred to form dimethyl ether(DME) instead of hydrocarbons,much less to isobutene.Oxygen defects (ODefects) analyzed by X-ray pho-toelectron spectroscopy (XPS) provided evidence that more ODefects occupied on the surface of ZrO2 cat-alysts with smaller crystalline size.Electron paramagnetic resonance (EPR) and ultraviolet-visible diffuse reflectance (UV-vis DRS) confirmed the presence of high concentration of surface defects and Zr3+ on m-ZrO2-5.9 sample,respectively.In situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) analysis indicated that the adsorption strength of formed formate species on catalyst reduced as the crystalline size decreased.These results suggested that surface defects were responsible for CO acti-vation and further influenced the adsorption strength of surface species,and thus the products distribu-tion changed.This study provides an in-depth insight for active sites regulation of ZrO2 catalyst in CO hydrogenation reaction.
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