Boron doped graphitic carbon nitride with acid-base duality for cycloaddition of carbon dioxide to epoxide under solvent-free condition
Boron doped graphitic carbon nitride with acid-base duality for cycloaddition of carbon dioxide to epoxide under solvent-free condition
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DOI：
10.1016/j.apcatb.2017.07.041
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发表时间：
2017-12
影响因子：
22.1
通讯作者：
Junjiang Zhu;Tingting Diao;Wenyao Wang;Xuelian Xu;Xiaoying Sun;S. Carabineiro;Zhen Zhao
中科院分区：
文献类型：
--
作者：
Junjiang Zhu;Tingting Diao;Wenyao Wang;Xuelian Xu;Xiaoying Sun;S. Carabineiro;Zhen Zhao
二氧化碳与环氧化物在无溶剂条件下的环加成反应生成环状碳酸酯，是环境科学和绿色化学中利用二氧化碳的一种环保途径。在本文中，我们报道了掺硼氮化碳(BCN)对此类反应具有很高的活性和选择性。BCN，特别是如果负载在介孔二氧化硅SBA-15(即B0.1CN/SBA-15)上，即使在无溶剂的条件下，对二氧化碳和环氧苯乙烷(SO)的环加成反应也显示出95%以上的转化率和选择性。这主要是由于B掺杂引起的酸碱二元性，使得二氧化碳和环氧化物能够共同激活。提出了一种基于酸碱二元性的机理，其中CO2在碱性>；NH位上被活化，而在酸性−B(OH)2位上则通过氢键被活化。共活化的二氧化碳等相互反应生成SC。密度泛函理论(DFT)计算结果表明，BCN等分子对CO2的共吸附是有利的，反应遵循Langmuir-HinShelwood机理。具有酸碱二元性的BCN为二氧化碳利用提供了一种廉价、绿色、高效的催化剂。
The cycloaddition of CO2and epoxides to yield cyclic carbonate under solvent-free conditions is an eco-friendly way to utilize CO2in environmental science and green chemistry. In this paper, we report that boron doped carbon nitride (BCN) is highly active and selective for such reactions. BCN, especially if supported on mesoporous silica SBA-15 (i.e., B0.1CN/SBA-15), shows above 95% conversion and selectivity for cycloaddition of CO2and styrene oxide (SO) to yield styrene carbonate (SC), even under solvent-free conditions. That is mainly due to the acid-base duality induced by B doping, which enables the co-activation of CO2and epoxide. A mechanism based on acid-base duality is proposed, where CO2is activated on the basic >NH sites and SO is on the acidic −B(OH)2sites through a hydrogen bonding. The co-activated CO2and SO react with each other to yield the SC. Density functional theory (DFT) calculations were conducted to support the mechanism, which show that the co-adsorption of CO2and SO on BCN is energetically favorable and the reaction follows the Langmuir-Hinshelwood mechanism. The BCN with acid-base duality provides an option for cheap, green and efficient catalysts for CO2utilization.