Effect of silanol content in silica support on catalytic performance of silica-anchored organotin catalyst for transesterification
(2.University of Chinese Academy of Sciences, Beijing, China 100049)
(3.School of Chemistry and Chemical Engineering, Henan Institute of Science and Technology, Xinxiang, Henan, China 453003)
【Abstract】Silica-anchored organotin catalysts were synthesized by a new synthetic scheme. It involved the synthesis of organotin-silane during the preparation of organotin using inorganic SnCl4 as tin precursor, which was then anchored on the silicas for the transesterification of DMC with phenol to diphenyl carbonate. A series of silica supports containing different silanols were obtained by different preparations along with different treatments. The TG and ICP characterizations showed that the Sn loading of the catalyst had positive correlation with the silanol content of the silica support. The 29Si MAS NMR measurements indicated that the prepared catalysts possessed many T2 and T3 species, which was in favor of the stability. The more silanol the silica support contained, the more Sn the catalyst supported, and the more active the catalyst would be. Sn-MSiO2, the catalyst with the mesoporous silica support, exhibited the best catalytic performance: with a reaction temperature of 150 °C–180 °C for 9 h, and a catalyst amount of 1.0 g, the phenol conversion and the transesterification selectivity reached 50.4% and 99.9%, respectively; in recycle test with a catalyst amount of 0.5 g, the phenol conversion decreased from 41.2% to 35.0% after five runs. Sn leaching was the main reason for the decline of catalytic activity.
【Keywords】 organotin; anchor; silanol; diphenyl carbonate; phenol; transesterification;
(Translated by WANG YX)
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