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采用了简单的衔接手法，行文流畅；使用了部分简单的长难句，可适当增加一些复杂的长句；词汇表达灵活丰富请继续保持，也能较好的使用一定的高级词汇。
All reagents were commercially supplied by Sinopharm Chemical Reagent Co., Ltd and used without further purification. They were of analytical grade and the purity of CO2 was 99.99%. 2.2 Preparation of Cu(acac)2/n-Bu4NBr/Fe3O4@MCM-41 Fe3O4@MCM-41 was prepared according to the procedures reported previously [27,28]. Typically, 1.0 g Fe3O4@MCM-41, 0.371 g n-Bu4NBr, 0.151 g Cu(acac)2 and 20 mL methanol were added into a 100 mL flask. The mixture was heated at reflux for 3 h, the solid was then collected by an external magnet and dried at 150 oC under vacuum for 10 h. The Cu and Br loadings were determined by atomic absorption spectroscopy (AAS) and ion chromatography (IC), respectively. In the as-prepared catalyst, 2.4 and 5.9 wt.% Cu and Br loading were given. 2.3 Catalytic performance of Cu(acac)2/n-Bu4NBr/Fe3O4@MCM-41 Typically, 20 mmol SO and 0.712 g Cu(acac)2/n-Bu4NBr/Fe3O4@MCM-41 (containing 0.267 mmol Cu2 and 0.534 mmol Br-) were charged into a 50 mL stainless steel autoclave. The autoclave was sealed and flushed with 1 MPa CO2 three times to extrude the air in it. The mixture was heated to 100 oC under stirring and CO2 was then introduced into the autoclave to 8 MPa using a high-pressure pump. The pressure in the autoclave was gradually released after continuous heating at 100 oC for 3 h. The reaction mixture was cooled to room temperature, followed by the addition of 10 mL CH2Cl2. The supported catalyst was collected by a permanent magnetand dried at 150 oC for 10 h under vacuum, then reused in the next run without further pretreatment. The quantitative and qualitative analysis of the liquid mixture was conducted by gas chromatography (GC) and gas chromatography mass spectrometry (GC-MS), respectively. Biphenyl was used as internal standard to determine the conversion of SO, the yield and the selectivity towards SC based on charged SO. After removing solvent by rotary evaporation and dried at 100 oC, crude product contained in the mixture liquid was collected for proton nuclear magnetic resonance spectroscopy (1H-NMR). 2.4 Determination of conversion, yield and selectivity The conversion of SO, the yield and the selectivity to SC were determined based on charged SO. The conversion, yield and selectivity were calculated according to the following equations.
