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首次在共沉淀过程中添加18-冠-6醚络合生成的钾离子得到了均一的高活性冠醚络合的锌-钴双金属催化剂,并用红外光谱(FTIR)、扫描电镜(SEM)、热重红外(TGA-IR)和X射线衍射(XRD)进行了表征.元素分析发现K含量为1.2%.FTIR表明未加冠醚络合的双金属催化剂离心后上下部分呈现不同的络合状态,而冠醚络合的双金属催化剂仍保持均一.SEM表明冠醚络合的双金属催化剂为均一松散的结构.由于生成的钾离子被冠醚络合,不影响聚合反应效果.TGA-IR表明冠醚不仅络合K离子,还参与对金属活性中心的络合.XRD表明此催化剂具有低的结晶度.所制冠醚络合的锌-钴双金属催化剂能成功催化CO2与环氧丙烷共聚,其中CDMC3催化得到的共聚物碳酸酯含量为47.8%,副产物环状碳酸酯为1.5%,催化效率高达5122 g/g催化剂(32600 g/g Zn),明显优于不添加冠醚以同样工艺制备的DMC1(共聚物碳酸酯含量29.2%,副产物环状碳酸酯3.3%,催化效率4100 g/g催化剂(16300g/g Zn).与不添加冠醚8次洗涤离心得到的DMC2相当(共聚物碳酸酯含量48.3%,副产物环状碳酸酯含量2.4%,催化效率5073 g/g催化剂(16400 g/g Zn)).基于此结果提出了两步的反应机理假设.
For the first time, the potassium ion produced by the complexation of 18-crown-6 ether was added in the coprecipitation process to obtain a uniform and highly active crown ether complexing zinc-cobalt bimetallic catalyst. The structure of the catalyst was characterized by FTIR, SEM, (TGA-IR) and X-ray diffraction (XRD) .It was found by elemental analysis that the content of K was 1.2% .FTIR showed that the unmodified crown ether bimetallic catalyst showed different complexation state after centrifugation, While the crown ether complex bimetallic catalyst remained uniform.SEM shows that the crown ether complex bimetallic catalyst is a uniform loose structure.Because the generated potassium ions are complexation of the crown ether does not affect the polymerization reaction results.TGA-IR shows Crown ethers not only complex K ions, but also participate in the complexation of the active sites of the metal. XRD shows that the catalyst has low crystallinity. The prepared crown ether complexed zinc-cobalt bimetallic catalyst can catalyze the copolymerization of propylene oxide and propylene , Of which the CDMC3-catalyzed copolymer had a carbonate content of 47.8%, a by-product cyclic carbonate of 1.5% and a catalytic efficiency of 5122 g / g catalyst (32600 g / g Zn) Preparation of DMC1 (copolymer carbonate content of 29.2% by-product Cyclic carbonate 3.3%, catalytic efficiency 4100 g / g catalyst (16300 g / g Zn), which was equivalent to DMC2 obtained by washing centrifugation without crown ether 8 times (copolymer carbonate content 48.3%, by-product cyclic carbonate content 2.4%, catalytic efficiency 5073 g / g catalyst (16400 g / g Zn)) .According to the results, a two-step reaction mechanism hypothesis was proposed.