无溶剂催化加氢合成2,2’-二氯氢化偶氮苯

Synthesis of 2,2’-dichlorohydroazobenzene by catalytic hydrogenation without solvent

利用浸渍法制备铂碳催化剂,该催化剂在不使用溶剂的条件下催化加氢邻硝基氯苯合成2,2’-二氯氢化偶氮苯的反应中有较高的活性。对该反应进行工艺优化得到最优条件为:氢氧化钠质量分数为30%、反应时间为9h、反应温度为90℃、反应压力为0.6~0.8MPa、搅拌转速为800r/min、铂碳催化剂质量分数为0.4%(以干基对邻硝基氯苯的质量计)、2,3-二氯-1,4-萘醌的质量分数为0.4%、十二烷基苯磺酸钠的质量分数为0.8%。在最优条件下催化剂重复使用14次,2,2’-二氯氢化偶氮苯的收率稳定在93.4%左右。通过TEM、ICP、BET等手段对新鲜和失活的催化剂进行表征,结果发现催化剂载体部分孔道堵塞与晶粒长大是催化剂失活的主要原因。

Pt/C catalyst is prepared by means of the impregnation method,which has a high activity in the hydrogenation of o-chloronitrobenzene to make 2,2’-dichlorohydroazobenzene without organic solvent.The optimal reaction conditions are obtained as follows: the reaction time is 9 h,reaction temperature at 90℃,reaction pressure 0. 6-0. 8 MPa,stirring speed 800 rpm,and the contents of catalyst,2,3-dichloro-1,4-naphthopuinone and sodium dodecyl benzene sulfonate are 0. 4%,0. 4% and 0. 8% respectively on the basis of dry o-chloronitrobenzene. Under these conditions,the catalyst can be reused for 14 times and the yield of 2,2’-dichlorohydroazobenzene can be stabilized at around 93. 4%.The fresh and deactivated Pt/C catalyst both are characterized by means of TEM,ICP,BET. It is found that catalyst deactivation is because a part of the pores of the catalyst carrier is blocked and the catalyst crystal grains grow.