Catalytic dehydration of ethanol over WOx nanoparticles supported on MFI (Mobile five) zeolite nanosheets

Abstract

Ethylene can be synthesized in a renewable manner by dehydrating bioethanol over supported metal oxide nanoparticle catalysts. Here, a series of nanoparticulate tungsten oxides supported on MFI (Mobil five) zeolite nanosheets was prepared at different W loadings (1 to 6 mol %) using the incipient wetness method and investigated with respect to the ability to catalyze the dehydration of ethanol. The resulting samples were characterized by X-ray diffraction, electron microscopy, N2 isotherms, X-ray absorption fine structures, and by the temperature-programmed desorption of NH3. The results obtained showed that WOx nanoparticles were homogeneously distributed over the entire void space of nanosheet samples up to a loading of 2 mol %, after which large WOx nanoparticles with needle-like morphology were formed on the surface of the zeolite nanosheet beyond 2mol%. The number of acid sites increased with WOx loading and, as a result, EtOH conversion progressively increased with WOx loading up to 6 mol %. At reaction temperatures of >390◦C, homogeneously distributed WOx nanoparticles showed slightly higher ethylene selectivity than nano-needle structured WOx. However, nano-needle structured WOx exhibited greater catalytic stability. In terms of ethylene yield over 8 h, needle-like WOx nanoparticles were found to be more suitable for the acid-catalyzed dehydration of ethanol than small-sized WOx nanoparticles.