硅羥基對二氧化硅固載有機錫酯交換催化性能的影響
發(fā)布時間:2018-06-03 20:57
本文選題:有機錫 + 固載。 參考:《化工學報》2017年05期
【摘要】:采用新方法制備了二氧化硅固載有機錫。以無機Sn Cl4為錫源,在合成有機錫的同時制備有機錫硅烷試劑,再將其固載到二氧化硅上,用于碳酸二甲酯與苯酚酯交換合成碳酸二苯酯的反應。通過不同的制備方法和處理方法,制得不同硅羥基含量的二氧化硅載體;研究硅羥基對錫固載量及固載有機錫催化性能的影響。TG與ICP表征顯示,錫固載量與二氧化硅載體的硅羥基含量正相關(guān)。29Si MAS NMR表征發(fā)現(xiàn),制備的固載有機錫中含有較多的T2和T3物種,利于有機錫的穩(wěn)定固載。二氧化硅硅羥基含量越高,催化劑的錫固載量越高,活性越好。介孔二氧化硅為載體制備的Sn-MSiO_2表現(xiàn)出最好的催化活性:用量1.0 g,在150~180℃反應9 h,苯酚轉(zhuǎn)化率達50.4%,酯交換選擇性高于99.9%;用0.5 g考察重復使用性能,重復使用5次,苯酚轉(zhuǎn)化率由41.2%降低到35.0%。錫流失是活性下降的主要原因。
[Abstract]:Silica supported organotin was prepared by a new method. Organotin silane reagents were synthesized from inorganic Sn Cl4 as tin source and immobilized on silica to synthesize diphenyl carbonate by transesterification of dimethyl carbonate with phenol. Silica carriers with different silica hydroxyl contents were prepared by different preparation and treatment methods, and the effects of silica hydroxyl groups on tin immobilization capacity and catalytic properties of organotin were investigated by TG and ICP. The results showed that there were more T _ 2 and T _ 3 species in the supported organotin, which was beneficial to the stable fixation of organotin. The higher the hydroxyl content of silica, the higher the tin immobilization capacity and the better the activity of the catalyst. The Sn-MSiO_2 prepared by mesoporous silica as carrier showed the best catalytic activity: dosage 1.0 g, reaction at 150 鈩,
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