Highly active and selective binary MgO-SiO2 catalysts for the production of 1,3-butadiene from ethanol

• Published in: Catalysis science & technology Vol. 7; no. 1; pp. 168 - 18
• Main Authors: Huang, Xiaoxiong, Men, Yong, Wang, Jinguo, An, Wei, Wang, Yuanqiang
• Format: Journal Article
• Language: English
• Published: 01.01.2017
• Subjects: Butadiene; Catalysis; Catalysts; Ethanol; Ethyl alcohol; Magnesium oxide; Silicon dioxide; Surface chemistry
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/c6cy02091g

A series of magnesia-silica binary composite catalysts with different molar ratios were prepared using various preparation methods and evaluated for the one-step production of 1,3-butadiene (BD) from bio-ethanol. The MgO-SiO 2 catalyst prepared by wet-kneading is distinguished from the samples prepared by other methods by its superior activity. An exceptionally high productivity of butadiene with the high ethanol conversion of 95% and BD selectivity of 77% was obtained over wet-kneaded hierarchical flower-like MgO nanostructures with the catalytic material made up of SiO 2 spheres (with a MgO : SiO 2 molar ratio of 65 : 35 at 450 °C and an WHSV of 4.1 h −1 ), which translates into an unprecedented BD yield of 0.025 mol g cat −1 h −1 . The as-prepared catalysts were characterized by XRD, FESEM, BET, FT-IR, UV/vis, CO 2 -TPD and NH 3 -TPD. The Mg precursor used and the preparation method are found to influence the extent of MgO and SiO 2 interactions during preparation, as estimated by various techniques, which, in turn, was found to correlate with the catalytic performance. A subtle balance of surface acidity/basicity was found to be necessary to achieve a high butadiene yield which can be obtained by variation of MgO : SiO 2 ratios in wet-kneaded samples. In view of the difference in catalytic activity and the physicochemical properties of the MgO-SiO 2 composite catalysts, the Si-O-Mg chemical bond formed by the strong MgO and SiO 2 interaction is suggested to be essential for the balanced surface acid/base sites in relation to the strong interaction between MgO and SiO 2 and the consequent high catalytic performance. Wet-kneaded binary MgO-SiO 2 composite catalysts gave exceptionally high productivity of butadiene governed by a subtle balance of acid-base sites in relation to the formation of an interfacial Si-O-Mg linkage and by varying preparation methods and MgO to SiO 2 ratios.