Mechanism and catalytic performance for direct dimethyl ether synthesis by CO2 hydrogenation over CuZnZr/ferrierite hybrid catalyst

Maohong Fan , Qingtao Sheng , Run-Ping Ye , Weibo Gong , Xiufeng Shi , Bang Xu , Morris Argyle , Hertanto Adidharma


Received September 24, 2019,Revised , Accepted February 10, 2020, Available online February 21, 2020

Volume 32,2020,Pages 106-117

Direct synthesis of dimethyl ether (DME) by CO2 hydrogenation has been investigated over three hybrid catalysts prepared by different methods: co-precipitation, sol-gel, and solid grinding to produce mixed Cu, ZnO, ZrO2 catalysts that were physically mixed with a commercial ferrierite (FER) zeolite. The catalysts were characterized by N2 physisorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature programmed desorption of CO2 (CO2-TPD), temperature programmed desorption of NH3 (NH3-TPD), and temperature programmed H2 reduction (H2-TPR). The results demonstrate that smaller CuO and Cu crystallite sizes resulting in better dispersion of the active phases, higher surface area, and lower reduction temperature are all favorable for catalytic activity. The reaction mechanism has been studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Methanol appears to be formed via the bidentate-formate (b-HCOO) species undergoing stepwise hydrogenation, while DME formation occurs from methanol dehydration and reaction of two surface methoxy groups.

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