CBDK加氢制备CBDO的动力学研究

Study on Kinetics of Hydrogenation of CBDK to CBDO

2,2,4,4-四甲基-1,3-环丁二醇(CBDO)是制备高性能共聚酯的重要单体,2,2,4,4-四甲基-1,3-环丁二酮(CBDK)加氢制备CBDO是其制备工艺的核心反应。在搅拌釜式反应器中对Ru/C催化剂上的CBDK加氢过程进行了反应动力学研究。通过高分辨透射电镜(HRTEM)对催化剂的微观形貌进行了观察,发现Ru金属均匀分布在活性炭表面,金属Ru颗粒的平均粒径为2~3 nm,这有利于提高催化剂的加氢活性和选择性。在排除传质影响的条件下,考察了催化剂浓度、温度、压力对加氢反应的影响,并通过参数回归得到了加氢反应的动力学模型。结果表明:该反应为连串反应,CBDK先快速加氢生成2,2,4,4-四甲基-1,3-环丁醇酮(CBKO),再进一步加氢生成CBDO;氢气分子态吸附,表面化学反应限速的Langmuir-Hinshelwood-Hougen-Watson(LHHW)动力学模型拟合效果最优。CBDK,CBKO与CBDO在催化剂活性位点上存在竞争吸附,吸附平衡常数分别为951.9,280.1和60.0 L/mol;两步反应的活化能分别为34.7 kJ/mol和47.9 kJ/mol。研究结果可为CBDK加氢反应器的设计与优化提供指导。

2,2,4,4-tetramethyl-1,3-cyclobutanediol(CBDO)is an important monomer for preparing high-performance polyesters.Hydrogenation of 2,2,4,4-tetramethyl-1,3-cyclobutanedione(CBDK)to CBDO is the core reaction of its preparation process.The kinetics of CBDK hydrogenation over Ru/C catalyst was studied in a stirred tank reactor.Through high resolution transmission electron microscope(HRTEM),observation on the micro morphology of the catalyst revealed that Ru was uniformly distributed on the surface with average particle diameter around 2-3 nm,which can enhance the hydrogenation activity and selectivity.The effect of catalyst mass,temperature and pressure on the hydrogenation reaction were investigated with mass transfer influences eliminated.The results showed that the reaction was a series reaction.CBDK was rapidly hydrogenated to produce 2,2,4,4-tetramethyl-1,3-cyclobutanol ketone(CBKO)and then further hydrogenated to produce CBDO.Langmuir-Hinshelwood-Hougen-Watson(LHHW)kinetic model based on hydrogen molecular state adsorption and surface reaction being the rate limitation gave the best fitting.There was competitive adsorption of CBDK,CBKO and CBDO on the active site of the catalyst,and the adsorption equilibrium constants were 951.9,280.1 and 60.0 L/mol,respectively.Activation energy of each step were 34.7 kJ/mol and 47.9 kJ/mol,respectively.The results can provide guidance for the design and optimization of the reactor of CBDK hydrogenation.