二氧化碳(CO2)既是造成温室效应的主要气体，也是一种重要的C1资源，CO2资源化利用是全球战略目标和研究热点，以CO2与环氧化合物为原料合成环状碳酸酯是其高效高值化利用的主要途径。为解决以往催化剂体系存在的催化剂稳定性差、催化活性低、催化剂制备复杂等问题，本研究以高稳定性的氧膦化合物与过渡金属盐进行复配，通过调控过渡金属盐和氧膦化合物的比例，形成不同配比的二元复合催化体系，优选了最佳过渡金属盐和最佳比例(三丁基氧膦与溴化锌摩尔比为2:1，即[2Bu3PO-ZnBr2])，考察了催化剂用量、CO2压力、反应时间、反应温度的影响，在最佳反应条件下(130℃, 3 h, 3 MPa)，环氧丙烷(PO)的转化率可达92%。通过相关表征揭示了膦基复合催化体系与反应物之间的相互作用，提出了可能的催化机理。[2Bu3PO-ZnBr2]催化体系在循环使用5次后，依然能够保持高催化活性。本研究提出的膦基二元复合催化体系可为催化剂设计和CO2利用提供思路。
Carbon dioxide (CO2) is both a major contributor to the greenhouse effect and an important C1 resource. The synthesis of cyclic carbonates from CO2 and epoxides is an important way of high efficiency and high value utilization. The development of high efficiency catalyst is the focus of research for this reaction. In the past, there were some problems such as poor stability, low catalytic activity and complex preparation of catalyst. Therefore, the aim of this study was to develop phosphine-based catalysts with high catalytic activity, low price and good stability. In this study, a binary composite catalytic system was formed between phosphine oxide compound and metal salt with high stability. By regulating different proportions of metal salts and phosphine oxide compounds, the binary composite catalytic system with different proportions was formed, and the optimal transition metal salts and the optimal ratio were selected (Bu3PO:ZnBr2=2:1, namely [2Bu3PO-ZnBr2]). The influence of catalyst dosage, CO2 pressure, reaction time, and reaction temperature on propylene oxide (PO) conversion and the selectivity of propylene carbonate (PC) was investigated. The results showed that under optimum reaction conditions (130℃, 3 h, 3 MPa), the PO conversion was 92%, the PC selectivity was 99% and the catalyst maintained high catalytic activity after five cycles. Finally, the interactions between the phosphine-based binary composite catalytic system and the reactants were revealed through relevant characterization, and the Lewis acid co-catalytic mechanism was proposed. The phosphine-based binary composite catalytic system proposed in this study provides a new idea for efficient and inexpensive catalyst utilization.
