超临界CO_2萃取再生失活Pd/C催化剂

对苯甲酸加氢过程中Pd/C催化剂的失活原因进行了分析,研究了利用超临界CO2萃取再生失活Pd/C催化剂的过程,考察了萃取温度、萃取压力、CO2流量、共溶剂种类对Pd/C催化剂再生效果的影响。研究结果表明,超临界CO2萃取可以有效去除Pd/C催化剂表面吸附的有机杂质,恢复Pd/C催化剂的活性。利用超临界CO2萃取再生失活Pd/C催化剂的较佳工艺条件:萃取温度333~353K,萃取压力15~25M Pa,CO2流量(1g催化剂、常温、常压)20mL/h,以甲苯和二氯甲烷混合物为共溶剂。工业试验结果表明,在催化剂处理量320kg、萃取温度353K、萃取压力20M Pa、萃取时间12h、超临界CO2流量1.5t/h、无共溶剂的条件下,失活Pd/C催化剂的活性可达到新鲜Pd/C催化剂活性的80%以上。

Regeneration of Deactivated Pd/C Catalyst by Supercritical CO2 Extraction

The deactivation of palladium carbon catalyst in hydrogenation of benzoic acid was analyzed and process for regenerating Pd/C catalyst was investigated by supercritical CO_2 extraction elsewhere outside the reactor.Effects of process conditions,namely temperature,pressure,CO_2 flow rate,and cosolvent on activity of Pd/C catalyst were studied.Activity of Pd/C catalyst regenerated by supercritical CO_2 extraction was satisfactory.The optimal regeneration conditions were as follows:temperature 333—353K,pressure 15—25MPa,CO_2 flow rate(1g catalyst,normal temperature and normal pressure)20mL/h,cosolvent methylene chloride+ toluene.Industrial regeneration of deactivated Pd/C catalyst in a 500L commercial unit(320kg catalyst)showed that about 80% of catalyst activity was recovered by supercritical CO_2 extraction when regeneration took place at 353K,20MPa,1.5t/h of CO_2 flow rate,12h and without cosolvent.