Contrasting structure-property relationships in amorphous, hierarchical and microporous aluminophosphate catalysts for Claisen-Schmidt condensation reactions
Contrasting structure-property relationships in amorphous, hierarchical and microporous aluminophosphate catalysts for Claisen-Schmidt condensation reactions
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DOI：
10.1016/j.apcata.2021.118376
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发表时间：
2021-09
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通讯作者：
Hamza Annath;J. Manayil;Jillian M. Thompson;A. C. Marr;R. Raja
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作者：
Hamza Annath;J. Manayil;Jillian M. Thompson;A. C. Marr;R. Raja
无定形铝磷酸盐是在醇醛型缩合、脱水和烷基化中具有活性的工业催化剂。人们对这些材料中存在的活性位点的内在性质知之甚少。在此，我们报告了对无定形和结晶铝磷酸盐（AFI 拓扑）及其相应的含铁类似物中催化活性位点的比较研究，采用苯乙酮和苯甲醛的克莱森-施密特缩合作为测试反应。通过分层多孔 HP FeAlPO-5 中的软模板方法产生的二次孔隙，以及无定形 Am FeAlPO 中大介孔的存在，导致了质量传输的改善和羰基的高转化率。这些材料中活性酸性位点的性质和浓度通过吡啶-DRIFTS 和丙胺-TPD 研究进行了表征，并被证明在羰基的活化和更好的催化性能中发挥着至关重要的作用。 Am FeAlPO(5) 的性能几乎优于 HP FeAlPO-5，从而为扩大工业和制药应用范围提供了一种有前景的替代品。
Amorphous aluminophosphates are industrial catalysts that are active in aldol-type condensations, dehydration and alkylation. The intrinsic nature of the active sites present in these materials is poorly understood. Herein we report a comparative investigation of the catalytic active sites in amorphous and crystalline aluminophosphates (AFI topology) and their corresponding iron-containing analogues, employing Claisen-Schmidt condensation of acetophenone and benzaldehyde as the test reaction. Secondary porosity generated via the soft-templating approach in hierarchically-porous HP FeAlPO-5, and the presence of large mesopores in amorphous Am FeAlPO resulted in improved mass-transport and high conversion of carbonyls. The nature and concentration of the active acidic sites within these materials were characterized by pyridine-DRIFTS and propylamine-TPD studies and was shown to play a crucial role in the activation of carbonyl groups and better catalytic performance. Am FeAlPO(5) nearly outperformed HP FeAlPO-5, thus providing a promising alternative for expanding scope in industrial and pharmaceutical applications.