双氧水预处理对钯炭催化剂结构与性能的影响

Influence of hydrogen peroxide pretreatment on structure and properties of Pd/C catalysts

采用不同质量分数的双氧水对椰壳活性炭预处理,然后以浸渍法制备了精对苯二甲酸(PTA)精制用钯炭催化剂。通过扫描电子显微镜,能谱分析,X射线衍射分析及氮气吸附脱附测试等手段,研究了双氧水预处理对所制得的钯炭催化剂结构与性能的影响。结果表明:经双氧水处理活性炭载体后,所得钯炭催化剂活性随双氧水浓度先增大后减小,双氧水质量分数为20%时,催化剂活性达到最佳;吸附脱附分析表明,双氧水预处理使钯炭催化剂平均孔径和中孔孔容有所增加;能谱测试表明,双氧水处理可以向载体表面引入氧元素;双氧水预处理对钯炭催化剂物相无影响;双氧水预处理可以增大活性炭的有效负载面积,并引入氧化性基团,以促进钯在载体的分散,提高催化活性。

Palladium-carbon （Pd/C） catalysts for purified terephthalic acid （PTA） purification was prepared by immersion method from coconut activated carbon pretreated with hydrogen peroxide of different mass fractions.The influence of hydrogen peroxide pretreatment on the structure and properties of Pd/C catalysts was studied by scanning electron microscopy,energy-dispersive X-ray analysis,X-ray diffraction method and nitrogen adsorption and desorption test.The results showed that the activity of Pd/C catalysts was increased first and then decreased with the increase of hydrogen peroxide concentration and was optimized at 20% hydrogen peroxide by mass fraction as the activated carbon carrier was treated with hydrogen peroxide.The adsorption-desorption analysis results indicated that hydrogen peroxide pretreatment raised the average pore diameter and mesopore volume of Pd/C catalysts in some degree.The energy-dispersive X-ray analysis results showed that hydrogen peroxide pretreatment could introduce oxygen element onto the carrier surface,increase the effective load area and introduce oxidative groups,leading to the better dispersion of palladium in the cartier,thus the catalytic activity could be improved; and hydrogen peroxide pretreatment had no effect on the phase of Pd/C catalysts.