Na_2S滴定法测定Pd/C催化剂制备过程中H_2PdCl_4前驱体的吸附  

Na_2S Titration Method Using for the Determination of H_2PdCl_4 Adsorption in the Preparation of Pd/C Catalysts

作　　者：梁秋霞[1] 马磊[1] 卢春山[1] 张群峰[1] 李小年[1] 

机构地区：[1]浙江工业大学工业催化研究所,绿色化学合成技术国家重点实验室培育基地,浙江杭州310032

出　　处：《高校化学工程学报》2008年第6期941-946,共6页Journal of Chemical Engineering of Chinese Universities

基　　金：浙江省科技计划项目资助(2004C21029;2005C11023-01)

摘　　要：为了研究Pd前驱体在活性炭表面的平衡吸附量和吸附态,了解影响Pd/C催化剂中Pd粒径的因素以及Pd颗粒的生长过程,提出了使用Na2S滴定法测定Pd/C催化剂制备过程中H2PdCl4在活性炭载体上平衡吸附量的方法,比较研究了一次性和逐滴性前驱体加入方式对Pd/C催化剂中Pd粒径的影响,实验结果表明逐滴加入法制备所得的催化剂的Pd粒径明显小于一次性加入法制备的催化剂,但H2PdCl4在活性炭表面平衡吸附量的变化并不如此明显,表明Pd前驱体平衡吸附量与催化剂Pd粒径之间并不存在对应关系。由H2-TPR实验结果可知,与一次性加入法制备Pd/C催化剂相比,逐滴加入法制备Pd/C催化剂的过程中发生还原的Pd前驱体较多。由此推断在催化剂制备过程中,Pd金属粒径的生长主要受到Pd0初始晶核的生成速率及前驱体扩散速率的影响。In order to investigate the equilibrium uptake and the adsorption state of the Pd precursor （[PdCl4]^2-） adsorbed on the activated carbon support （ACS） and the factors influencing the size and the growth of the adsorbed Pd particle on the ACS, the Na2S titration method was proposed to be used during the preparation of Pd/C catalyst for the determination of the H2PdCl4 equilibrium uptake on the ACS. In this study, Pd/C catalysts were prepared by two methods separately, the method of Pd precursor added in drop-wise and the method of added in one portion, and the Pd particle sizes on ACS obtained by these two methods were compared. The results show that the Pd particle size of Pd/C catalyst prepared by H2PdCl4 added in drop-wise （Pd/C（x%）-D） is much smaller than that prepared by H2PdCl4 added in one portion （Pd/C（x%）-T）, however the equilibrium Pd precursor uptake of these two methods is almost the same. It indicates that the equilibrium Pd precursor uptake does not highly depend on the particle size of the Pd/C catalysts. H2-TPR profiles of Pd/C catalysts show that, compared with Pd/C（x%）-T, much more Pd precursors [PdCl4]2- were reduced during preparation of Pd/C（x%）-D. It suggests that the Pd particle size of Pd/C catalysts highly depends on the generation rate of initial crystal nucleus Pd^0 and the diffusion rate of Pd precursor.

关 键 词：Na2S滴定法 PD/C H2PdCl4吸附 Pd粒径 

分 类 号：TQ426.81[化学工程] TQ028.15