pH值对粗对苯二甲酸加氢精制Pd/C催化剂性能的影响

采用不同pH值的浸渍液制备了粗对苯二甲酸(CTA)加氧精制Pd/C催化剂,考察了浸渍液的pH值对CTA中的主要杂质对羧基苯甲醛(4-CBA)的加氢精制性能的影响,并采用XRD、TEM等手段对催化剂进行了表征.结果表明,浸渍液的pH值为3.0时,金属Pd以微晶的形式高度分散在活性炭载体上,Pd/C催化剂的活性最高,在反应...

EFFECT OF pH VALUE ON THE PERFORMANCE OF Pd/C CATALYST FOR HYDROPURIFICATION OF CRUDE TEREPHTHALIC ACID

A series of Pd/C catalysts for hydropurification of crude terephthalic acid（CTA） were prepared by impregnating with solutions having various pH values,and the prepared catalysts were characterized by XRD and TEM techniques.Effects of impregnation pH values on the performance of catalyst during removing p-carboxy benzaldehyde（4-CBA）,the main impurity in CTA,were investigated.Results showed that catalyst prepared with an impregnation solution pH value of 3.0 exhibited the best catalytic activity,under a reaction temperature of 280℃,H₂ partial pressure of 0.6 MPa and a reaction time of 1.0 h,the conversion of 4-CBA over said Pd/C catalyst was almost 100%.In this catalyst the palladium particles were highly dispersed on the surface of active carbon and presented as microcrystalline structure.A comparison study was carried out between said Pd/C catalyst（prepared at pH value of 3.0） and an import catalyst. Under severe testing conditions and after repeating testing,the deactivation tendency and palladium sintering behavior of these two catalysts were similar,which indicated that the hydropurification performance of these two catalysts was in the same level.