Acid-activated and WO -loaded montmorillonite catalysts and their catalytic behaviors in glycerol dehydration

Autor: Shengfu Ji, Dongshen Tong, Hanbin Zhao, Hao Zhang, Chun Hui Zhou, Weihua Yu, Huimin Yang, Hao Wang, Pengpeng Wang
Rok vydání: 2017
Předmět:
Zdroj: Chinese Journal of Catalysis. 38:1087-1100
ISSN: 1872-2067
DOI: 10.1016/s1872-2067(17)62813-4
Popis: The use of H2SO4-, HCl-, H3PO4-, and CH3COOH-activated montmorillonite (Mt) and WOx/H3PO4-activated Mt as catalysts for the gas-phase dehydration of glycerol was investigated. The WOx/H3PO4-activated Mt catalysts were prepared by an impregnation method using H3PO4-activated Mt (Mt-P) as the support. The catalysts were characterized using powder X-ray diffraction, Fourier-transform infrared spectroscopy, N2 adsorption-desorption, diffuse reflectance ultraviolet-visible spectroscopy, temperature-programmed desorption of NH3, and thermogravimetric analysis. The acid activation of Mt and WOx loaded on Mt-P affected the strength and number of acid sites arising from H+ exchange, the leaching of octahedral Al3+ cations from Mt octahedral sheets, and the types of WOx (2.7 ≤ x ≤ 3) species (i.e., isolated WO4/WO6-containing clusters, two-dimensional [WO6] polytungstates, or three-dimensional WO3 crystals). The strong acid sites were weakened, and the weak and medium acid sites were strengthened when the W loading on Mt-P was 12 wt% (12%W/Mt-P). The 12%W/Mt-P catalyst showed the highest catalytic activity. It gave a glycerol conversion of 89.6% and an acrolein selectivity of 81.8% at 320 °C. Coke deposition on the surface of the catalyst led to deactivation.
Databáze: OpenAIRE
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