稀土金属氧化物对Pd/δ,θAl_2O_3催化蒽醌氢化制H_2O_2性能的影响

Effect of Rare Earth Oxides on Catalytic Performance of Pd/δ,θ-Al_2O_3 for Anthraquinone Hydrogenation to H 2O 2

采用湿浸法制备了用于蒽醌氢化制过氧化氢的系列氢化催化剂 .考察了不同稀土金属 (La ,Ce ,Pr,Nd和Sm)氧化物对Pd/δ ,θ Al2 O3 催化剂性能的影响 .采用XRD ,H2 O2 滴定和N2 物理吸附等技术对催化剂进行了表征 .结果表明 ,适量稀土金属氧化物的加入能抑制高温处理时Al2 O3 晶粒的增长 ,增大催化剂比表面积 ,提高金属Pd的分散度 ,从而提高催化剂的氢化活性 .稀土金属氧化物对Pd/δ ,θ Al2 O3 催化性能的影响顺序为La >Nd >Pr >Sm >Ce.

Pd/δ,θ-Al 2O 3 catalyst samples promoted with rare earth oxides for anthraquinone hydrogenation to H 2O 2 were prepared by impregnating δ,θ-Al 2O 3 with aqueous solutions of rare earth nitrate and PdCl 2 successively. The effect of the rare earth oxides on the catalytic performance of Pd/δ,θ-Al 2O 3 catalyst was investigated by means of XRD, N 2 adsorption and H 2-O 2 titration techniques. The results showed that the rare earth oxides are good promoters of Pd/δ,θ-Al 2O 3 for the reaction, and they can inhibit the growth of alumina crystals at high temperature, increase the catalyst surface area, improve the Pd dispersion and enhance the catalytic activity effectively. The promotion effect of the rare earth oxides on the catalytic performance of Pd/δ,θ-Al 2O 3 catalyst for anthraquinone hydrogenation to H 2O 2 is in the order La>Nd>Pr>Sm>Ce.