【作者】 王庶；

【导师】 李光兴；

【作者基本信息】 华中科技大学 ， 材料物理与化学， 2011， 博士

【摘要】 本文主要研究了基于碳酸二甲酯与苯酚酯交换反应的碳酸二苯酯合成方法的类水滑石催化剂和加压酯交换-减压歧化二步法合成工艺。类水滑石催化剂对苯酚与碳酸二甲酯酯交换合成碳酸二苯酯反应的催化性能研究是在常压条件下进行的。在课题组前期工作的基础上,通过对影响类水滑石催化剂酯交换选择性的各种因素的研究,发现层间阴离子的碱性强弱对催化剂的选择性影响不大,影响类水滑石催化剂催化选择性的主要因素是催化剂制备过程中夹带的未洗净的强碱性沉淀剂。对此,针对性的优化了类水滑石催化剂的制备方法,使类水滑石催化剂的酯交换产物的选择性达到了95%,与前期工作相比提高了约12%。在优化的制备条件下,合成了多种不同阳离子类水滑石催化剂,用XRD、TG-DTA、FT-IR、BET对类水滑石催化剂进行了表征,测试了它们对苯酚与碳酸二甲酯酯交换反应的催化性能。研究结果表明,n(M2+)/n(M3+)=3的Mg/Fe类水滑石(Pyroaurite)的综合催化性能最好。在Mg/Fe原子比为3：1、苯酚与碳酸二甲酯的摩尔比为2：1、催化剂的质量分数为原料总质量的1.5%、反应时间8h的优化实验条件下,碳酸二甲酯的转化率达到61.5%,碳酸甲苯酯和碳酸二苯酯的产率分别达到43.7%和13.9%,酯交换产物的选择性达到93.7%。在实验研究的范围内(4次),Mg/Fe类水滑石的催化活性保持稳定不变。通过对类水滑石催化剂的催化性能与其结构和组成之间的关系的研究,发现三价阳离子的极化力大小影响类水滑石催化剂的活性高低,二价阳离子的极化力大小则影响其使用寿命长短：M3+的极化力大,类水滑石催化活性较好；M2+的极化力小,负离子配位八面体的层板结构稳定,类水滑石催化剂使用寿命长。通过对类水滑石催化剂失活原因以及再生方法的研究,发现类水滑石催化剂的特征层状结构是其具有催化活性的关键：层状结构稳定,催化剂使用寿命长；层状结构垮塌,催化活性随之消失。对于活性降低或已失活的类水滑石催化剂可以通过结构重建的方法再生。在课题组前期工作的基础上,依靠课题组自行研制的加压精馏反应釜,系统研究了苯酚与碳酸二甲酯酯交换合成碳酸二苯酯技术的加压酯交换-减压歧化二步法工艺,找到了工艺控制的关键点。工艺研究之始,就考虑了小试技术放大的可行性,各个工艺步骤基本按照产业化技术要求设置。在反应温度180℃、压力1.OMPa、反应时间6h、钛酸丁酯催化剂用量为苯酚质量的3%的优化工艺条件下,苯酚的单程转化率达到82%,碳酸二苯酯的单程分离收率达到44%,选择性大于99%,且钛酸丁酯催化剂在整个工艺过程中的催化性能稳定,分离损失小,能够循环套用。更多还原

【Abstract】 The Hydrotalcite-like catalysts and the transesterification-disproportionation two-step synthetic technology for the synthesis of diphenyl carbonate by transesterification from phenol and dimethyl carbonate were studied in this paper.The catalytic performance of hydrotalcite-like catalysts for transesterification between phenol and dimethyl carbonate was investigated under normal pressure. Based on the group’s former research work, various effects affecting the selectivity of hydrotalcite-like catalyst for transesterification products were investigated. It was found that the basic strength of the interlayer organic anions has little influence on the selectivity of hydrotalcite-like catalysts. The main effect affecting the selectivity of hydrotalcite-like catalyst for transesterification productsis is the remained basic co-precipitation agent (NaOH) in the catalyst preparation process. Therefore, by improvement of the hydrotalcite-like catalyst’s preparation procedure, the catalyst selectivity for transesterification products reached about 95%, at least 12% higher than the group’s former result.Various hydrotalcite-like catalysts with different combinations of cations were synthsized under the optimal preparation procedure, and characterized by XRD, TG-DTA, FT-IR and BET method. The catalytic performances of these synthtic hydrotalcite-like catalysts were tested for the transesterification reaction between dimethyl carbonate and phenol. It was found that the Mg/Fe-CO3 hydrotalcite-like catalysts (Pyroaurite) with the atomic ratio n(M2+)/n(M3+)=3 had the best catalytic performance. Under the optimal reaction condition of Mg/Fe atomic ratio of 3:1, n(phenol):n(DMC)=2:1, the mole of phenol=0.5, w(cat.)=1.5% of the total mass of phenol and DMC, time=9h, the conversion of DMC reached 61.5%, and the yields of diphenyl carbonate and methyl phenyl carbonate were 13.9% and 43.7%, respectively. The catalyst’s reuse experiment indicates that Pyroaurite catalyst can be recycled, seperated and regenerated easily within the scope of this study (4 runs).The relation between the catalytic performance and the structure and components of the hydrotalcite-like catalysts were investigated. It was found that the catalytic performance of the hydrotalcite-like catalysts is related to the character of involved cations. While the catalytic activity was influenced by trivalent cations, the life time of catalysts was influenced by divalent cations. From the investigation of the reason for the deactivation of hydrotalcite-like catalysts, it was found that the characteristic layered structure of the hydrotalcite-like catalysts was the key factor to their catalytic activities. Once the layered structure collapsed, the activities were lost. But the catalytic activity can be recovered by the structure reconstruction of the hydrotalcite-like compounds. These research results provide a theoretical foundation for the advancement of the catalytic performance of hydrotalcite-like catalysts.Based on the group’s former research, the transesterification-disproportionation two-step synthetic technology was studied using the self-made pressured reactive distillation reactor. Applying two-step process to the synthesis of diphenyl carbonate by the dimethyl carbonate’s phenolic transesterification, under the optimal reaction condition of 180℃, 1.0MPa, w%(cat./phenol)=3,6 h, the conversion per pass of phenol reached 82%, and the isolated yield per pass of diphenyl carbonate reached 44%. The catalyst’s reuse experiment shows that Ti(OBu)4 is a stable, recyclable catalyst for the synthesis of diphenyl carbonate using the transesterification-disproportionation two-step process.更多还原