研发环保、高效、稳定、低成本的无汞催化剂是我国基于煤化工路线的乙炔氢氯化法生产聚氯乙烯(PVC)的关键。针对铜基催化剂在乙炔氢氯化反应中活性低、稳定性差的问题,利用尿素小分子改性策略制备了一系列以新疆煤基炭负载的铜基催化剂(Cu/Urea-CAC),探究铜物种和尿素的加入量对铜基催化剂乙炔氢氯化催化性能的影响。结果表明,当铜负载量为20%、尿素引入量为15%,反应温度为160℃,乙炔空速为120h-1,氯化氢和乙炔原料的体积比为1.25的反应条件下,20Cu/15Urea-CAC催化剂的乙炔转化率可达92.6%,选择性始终大于98.2%,具有良好的催化性能。利用X射线光电子能谱(XPS)、X射线衍射(XRD)、扫描电镜(SEM)、N2物理吸脱附、等离子体发射光谱(ICP-OES)和热重(TG)技术对催化剂进行表征分析,认为适量尿素改性可抑制催化反应过程中Cu活性物种的还原、流失及催化剂表面积碳的形成,进而提升了新疆煤基炭负载铜催化剂的乙炔氢氯化催化性能。研究结果进一步拓展了新疆煤基炭的应用,也为乙炔氢氯化无汞新催化体系的设计合成及其催化作用提供了数据支撑。

Developing of environmental friendly,high-efficiency,stable and low-cost non-mercury catalyst is the key to PVC productionusing coal-route-based acetylene hydrochlorination. To improve the current problems of low catalytic activity and poor stability of copper(Cu)-based catalysts applied in the acetylene hydrochlorination reactions,a series of Cu/ Urea-CAC catalysts were prepared by urea modification strategies and the effects of the urea addition and Cu loading on the catalytic performances of catalysts for acetylene hydrochlorination were investigated. When the urea content is 15% and the Cu loading is 20%,the Cu/ Urea-CAC catalyst reveal the optimal catalyticperformance with the 92.6% C2H2 conversion and 98.2% vinyl chloride selectivity under the reaction conditions of 160 ℃ ,a C2 H2 gashourly space velocity of 120 h-1 and molar ratio of hydrogen chloride to acetylene is 1.25. Combination with the characterization results ofXPS,XRD,SEM,N2 adsorption and desorption,ICP -OES and TG techniques,it is suggested that the enhanced catalytic performanceis mainly related to the appropriate urea addition,which can effectively inhibit Cu species reduction and loss,and decrease the carbon deposition,thereby improving the catalytic performance activity of Cu-supported on Xinjiang coal-based carbon catalysts for acetylene hydrochlorination. The results will expand the application of Xinjiang coal-based carbon and provide theoretical support for the design,synthesisand catalysis of a new catalytic system for acetylene hydrochlorination.

0 引言

1 试验

   1.1 原料与试剂

   1.2 催化剂制备

   1.3 催化剂的评价

   1.4 催化剂的表征

2 结果与讨论

   2.1 催化剂的催化性能及优化

   2.2 尿素改性对催化剂活性相的影响

   2.3 尿素改性对催化剂结构的影响

   2.4 尿素改性对催化剂表面积碳的影响

3 结论