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研究了Cu、La、Ba、Ce和Co等多种金属氧化物对Pd/γ-Al2O3催化剂在3,5-二羟基苯甲酸转移加氢制备3,5-二氧代环己烷羧酸反应中的活性影响,发现镧的改性效果最明显.得到的Pd-LaOx/γ-Al2O3催化剂在150℃下还原,催化3,5-二羟基苯甲酸转移加氢反应的转化率和选择性分别达到了90.6%和98.2%.在150℃下PdCl2被还原为Pd,而La保持氧化态.经TPR、SEM、TEM、XPS等手段分析后认为,引入的La使Pd具有适宜的粒度,低温还原时保持氧化态的La与载体产生相互作用,并对Pd的转移加氢活性的提高有利,而高温下被还原的La则对提高Pd的活性不利.
The effects of various metal oxides such as Cu, La, Ba, Ce and Co on the catalytic hydrogenation of Pd / γ-Al2O3 catalyst in 3,5-dihydroxybenzoic acid to 3,5-dioxocyclohexanecarboxylic acid The results showed that the modification effect of lanthanum was the most obvious.The Pd-LaOx / γ-Al2O3 catalyst was reduced at 150 ℃ to catalyze the conversion and selectivity of 3,5-dihydroxybenzoic acid Reached 90.6% and 98.2%, respectively.The PdCl2 was reduced to Pd at 150 ℃, while La remained in oxidation state.Analysis by TPR, SEM, TEM and XPS showed that the introduced La had the proper particle size and low temperature reduction In the oxidized state, La interacted with the support and promoted the hydrogen transfer activity of Pd. However, La reduced at high temperature was unfavorable for increasing the Pd activity.