Naturally occurring phyllosilicate minerals such as talc and vermiculite in conjunction with n-tetra butyl ammonium bromide (TBAB) co-catalyst were found to be efficient in the coupling of CO2 with epoxides to form cyclic carbonates. The reaction was carried out in a pressurized autoclave reactor at moderate pressures of 10–35 bars and temperatures of 100–150 °C. The optimized catalyst system exhibited > 90% conversion of the epoxides and > 90% selectivity for the desired cyclic carbonates, in the presence or absence of a solvent. The selectivity of the catalytic system could be improved with heat pre-treatment of the phyllosilicates albeit this resulted in slightly lower epoxide conversion. The results obtained using the heat treated phyllosilicates strongly support the hydrogen bond assisted mechanism for the cycloaddition of epoxides and CO2. The cycloaddition reaction could also be carried out in the absence of TBAB, although lower cyclic carbonate yields were observed. The phyllosilicate part of the catalyst system is heterogeneous, easy to separate after completion of reactions and reusable a number of runs without loss of activity.

中文翻译：

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滑石粉和其他页硅酸盐催化的环氧化物和二氧化碳合成环状碳酸酯

发现天然存在的层状硅酸盐矿物（例如滑石粉和ver石）与正四丁基溴化铵（TBAB）助催化剂一起可有效地将CO2与环氧化物偶联形成环状碳酸盐。该反应在加压高压釜反应器中，在10-35 bar的中等压力和100-150°C的温度下进行。在存在或不存在溶剂的情况下，优化的催化剂体系对所需的环状碳酸酯表现出> 90％的环氧化物转化率和> 90％的选择性。可以通过对页硅酸盐进行热处理来提高催化体系的选择性，尽管这会导致环氧转化率略低。使用热处理的层状硅酸盐获得的结果有力地支持了环氧化物和CO2环加成的氢键辅助机理。环加成反应也可以在不存在TBAB的条件下进行，尽管观察到较低的环状碳酸酯收率。催化剂体系的页硅酸盐部分是非均质的，反应完成后易于分离，可重复使用许多次而不会失去活性。