选择性催化加氢合成3,4-二氯苯胺的Pd/C催化剂研究

研究了Pd/C催化剂表面金属钯平均粒径对3,4-二氯硝基苯催化加氢反应选择性的影响，发现金属钯平均粒径越大，脱氯副反应越不明显，加氢选择性越高。采用浓硝酸预处理的活性炭负载钯催化剂虽然能够增大表面金属钯平均粒径，粒径分布却较宽，不利于加氢选择性的提高。使用饱和EDTA·2Na溶液预处理活性炭后，在钯负载量降低的情况下，可以达到活性炭载体表面金属钯大粒径、狭窄的分布，实现了在不添加脱氯抑制剂的情况下高选择性合成3,4-二氯苯胺。

Synthesis of 3,4-dichioroaniline via selective hydrogenation over Pd/C catalyst

The effect of particle size of Pd in Pd/C catalyst on the selectivity for catalytic hydrogenation of 3, 4-dichloronitrobenzene was investigated. The experimental results indicated that better selectivity to 3, 4-dichloroaniline was obtained over Pd/C catalyst with larger Pd particle size, with less side reactions. Pd/C pretreated with concentrated nitric acid resulted in increasing Pd particle size, but was unfavorable to the selectivity to 3, 4-dichloroaniline due to wide distribution of Pd particle size. Perfectly narrow distribution of Pd particle with large particle size were attained over Pd/C pretreated with EDTA·2Na at lower Pd loadings, which lead to high-selectivity synthesis of 3, 4-dichloroaniline without presence of dechlorination inhibitor.