钯碳催化剂的制备条件对苯酚气相加氢制环己酮的影响

Effect of preparing conditions of Pd/C catalysts on vapour phase hydrogenation of phenol to cyclohexanone

采用浸渍法制备了Pd/C催化剂,考察了活性炭预处理方法、沉淀温度和还原方法对催化剂催化苯酚气相加氢制环己酮的影响。通过XRD和XPS对催化剂进行表征,考察了催化剂制备条件对Pd/C催化剂结构和催化活性的影响。结果表明:双氧水预处理可以向载体表面引入氧化性基团,促进钯在载体中的分散;在活性炭酸洗过程中进行搅拌,可以减少落粉的产生,提高催化剂的活性;沉淀温度升高会导致催化剂中Pd晶粒度变大;Pd晶粒度过小或过大都会导致催化剂活性下降;采用水合肼还原有利于提高催化剂的活性。

Pd / C catalysts are prepared by impregnation method and the effects of pretreatment method,precipitation temperature and reduction method on vapour phase hydrogenation of phenol to cyclohexanone are investigated. The catalysts are characterized by XRD,XPS techniques and the influence of preparation conditions on the structure and properties of Pd / C catalysts is studied. The results show that hydrogen peroxide pretreatment can introduce oxidative groups,lead to the better dispersion of palladium in the carrier.To join the stirring in the pickling process of active carbon can reduce the powder production,thus the catalytic activity can be improved. Higher precipitation temperature will lead to the increase of the crystal size of Pd. Whether the crystal size of Pd is too small or too large will cause the decrease of the catalytic activity. Using hydrazine hydrate reduction is beneficial to improve the activity of catalyst.