Effect of ionic radius and valence state of alkali and alkaline earth metals on promoting the catalytic performance of La2O3 catalysts for glycerol carbonate production
Effect of ionic radius and valence state of alkali and alkaline earth metals on promoting the catalytic performance of La2O3 catalysts for glycerol carbonate production
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DOI：
10.1016/j.cej.2023.141486
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发表时间：
2023-02
影响因子：
15.1
通讯作者：
Jialin Yu;Ke Wang;Shibo Shao;W. Li;Shangfeng Du;Xianfeng Chen;Cong Chao;Xi Fan
中科院分区：
文献类型：
--
作者：
Jialin Yu;Ke Wang;Shibo Shao;W. Li;Shangfeng Du;Xianfeng Chen;Cong Chao;Xi Fan
碱金属和碱土金属已被用来促进金属氧化物在甘油和碳酸二甲酯的酯交换反应中的催化性能，然而，掺杂剂对金属氧化物催化性能的促进作用尚未得到充分研究，这阻碍了低成本、高效的甘油和碳酸二甲酯酯交换反应催化剂的开发。本文首次系统研究了掺杂剂离子半径和价态、掺杂剂表面浓度以及催化剂碱度对La2O3在甘油与碳酸二甲酯酯交换反应中催化性能的影响。我们的结果表明，掺杂剂的离子半径和价态是决定因素，而碱性位点密度不是关键因素，尽管催化剂表面的碱性对于活化甘油和碳酸二甲酯很重要。在碱金属和碱土金属中，25 mol% Na/La2O3 催化剂在 70 °C 和 2 小时的反应中实现了最高的甘油转化率 (85%) 和碳酸甘油产率 (60%)。经过详细研究，提出了在Na/La2O3催化剂上甘油和碳酸二甲酯发生酯交换反应的合理机理。这项研究可以帮助了解碱金属和碱土金属的促进作用，其结果可以指导金属氧化物催化剂的未来设计。
Alkali metals and alkaline earth metals have been used to promote the catalytic performance of metal oxides in transesterification of glycerol and dimethyl carbonate, however, the promotional roles of the dopants in influencing the catalytic performance of the metal oxides have not been fully investigated which hinder the development of low-cost and high-efficiency catalysts in transesterification of glycerol and dimethyl carbonate. This paper, for the first time, systematically studied the influence of ionic radius and valence state of dopants, surface concentration of dopants and the basicity of the catalysts on the catalytic performance of La2O3in transesterification of glycerol and dimethyl carbonate. Our results suggest that the ionic radius and valence state of the dopants are the determining factors, while the basic site density is not a crucial factor, although the basicity of catalyst surface is important in activating glycerol and dimethyl carbonate. Among alkali and alkaline earth metals, 25 mol% Na/La2O3catalyst achieved the highest glycerol conversion (85 %) and glycerol carbonate yield (60 %) in the 70 °C and 2-hour reaction. After the detailed investigation, a plausible mechanism of glycerol and dimethyl carbonate transesterification on Na/La2O3catalyst has been proposed. This research could help understand the promotional role of alkali metals and alkaline earth metals and the results may guide future design of metal oxide catalysts.