【作者】 史芸；

【导师】 王胜平；

【作者基本信息】 天津大学 ， 化学工艺， 2008， 硕士

【摘要】 碳酸二苯酯（DPC）是非光气法合成聚碳酸酯的基本原料。近年来,聚碳酸酯以其良好的机械、光学和电子性能得到了广泛应用,从而使得DPC的研究与开发逐步成为人们关注的热点。以苯酚和草酸二甲酯（DMO）酯交换合成DPC是一条具有广泛发展前景的绿色合成工艺路线。本论文研究以DMO和苯酚为原料,通过酯交换反应合成用于制备DPC的甲基苯基草酸酯（MPO）和草酸二苯酯（DPO）,重点研究了钼钛固体酸催化剂在该酯交换反应中的催化性能。对钼钛双金属氧化物的活性考察表明,溶胶凝胶法制备的复合型MoO₃-TiO₂催化剂对酯交换反应的催化性能优于浸渍法制备的负载型MoO₃/TiO₂催化剂。催化剂的BET、XRD、XPS、FT-IR表征显示复合型催化剂中MoO₃与TiO₂分散均匀,并形成Mo-O-Ti键,具有良好的异质组分相容性。MoO₃在TiO₂载体表面的分散符合单层分散理论,在单层分散阈值附近MoO₃-TiO₂催化剂的催化活性最好,尤其有利于MPO歧化反应生成DPO,提高了DPO选择性。晶相MoO₃出现后,催化剂活性和DPO选择性均降低。考察了固体超强酸SO₄^2-/TiO₂对苯酚和DMO酯交换反应的催化活性。BET、XRD、XPS、FT-IR等测试表明通过SO₄^2-的改性抑制了TiO₂在焙烧过程中的结晶化程度,并提供了良好的孔隙结构,提高了催化剂的比表面积。SO₄^2-与Ti⁴⁺配位存在,由于S=O的强吸电子能力而产生强的电子诱导效应,从而产生超强酸中心。SO₄^2-/MoO₃-TiO₂固体酸催化剂对苯酚和DMO酯交换反应表现出优良的催化性能。BET、XRD、NH3-TPD表征显示,SO₄^2-对复合氧化物MoO₃-TiO₂表面有修饰作用,负载SO₄^2-后催化剂比表面积显著提高,酸量增大。MoO₃含量为1%的SO₄^2-/MoO₃-TiO₂催化活性最佳,DMO转化率达64.16%,DPO和MPO的收率分别达到14.31%和43.38%。更多还原

【Abstract】 Diphenyl carbonate （DPC） is an important organic material for non-phosgene production of polycarbonates （PCs）, which has been extensively applied with good performance in mechanics, optics and electronics. Much attention has been paid to the synthesis of DPC. And the transesterification of dimethyl oxalate （DMO） with phenol to diphenyl oxalate （DPO） followed by decarbonylation of DPO to DPC is a promising route. This paper disscused the process of methyl phenyl oxalate （MPO） and DPO synthesis from the transesterification of DMO with phenol, and focused on the catalytic activities of the molybdenum-titanium solid acid catalysts in the transesterification reactions.It was indicated that the catalytic activity of MoO₃-TiO₂ compound catalyst prepared by sol-gel method was better than the MoO₃/TiO₂ supported catalyst. The results of BET, XRD, XPS, FT-IR showed that the compound catalyst had a fine compatibility of heterogeneous components, in which MoO₃ and TiO₂ dispersed evenly with the Mo-O-Ti bond formed. The dispersion of MoO₃ on the surface of TiO₂ accorded with the theory of monolayer. The MoO₃-TiO₂ catalyst performed the best activity near the threshold of dispersed MoO₃ corresponds to a saturated monolayer. Especially, the disproportionation of MPO into DPO was accelerated and the selectivity to DPO was improved. When the crystal MoO₃ was formed, the activity of catalysts and the selectivity to DPO were both decreased.The catalytic activity of solid superacid SO₄^2-/TiO₂ was inspected. The characterization of XRD, XPS, FT-IR, NH3-TPD indicated that the modification of SO₄^2- could inhibit the crystallization of TiO₂ during calcinations and provide a fine pore structure. As a result, the specific surface area of catalyst was highly increased. SO₄^2- coordinated with Ti4 + and the super acid centre created owing to the strong electronic induced effects caused by S=O.By means of BET, XRD, NH3-TPD, the excellent performance of SO₄^2-/MoO₃-TiO₂ during the transesterification of DMO with phenol was related with the modification of SO₄^2-. Supported with SO₄^2-, the specific surface area of MoO₃-TiO₂ catalyst was increased evidently, and the quantity of acid site was also increased. The catalyst of SO₄^2-/MoO₃-TiO₂ with 1% MoO₃ performed best, giving 64.16% conversion of DMO, 14.31% and 43.38% yield of DPO and MPO respectively.更多还原