Pd-SiO_2催化剂制备、结构及其用于氢氧直接合成过氧化氢的反应性能

Preparation and Structure of Pd-SiO_2 Catalysts and Its Performance for Direct Synthesis of Hydrogen Peroxide from Hydrogen and Oxygen

利用水热法原位合成制备了一种活性组分Pd颗粒尺寸可控且表面具有一定酸性位的大孔容Pd-SiO_2催化剂。通过调节前驱液的pH值控制SiO_2层的结构性质,利用TEM、XRD、N_2吸附-脱附和NH3-TPD等手段对催化剂的结构和表面性质进行了表征分析,并考察了Pd-SiO_2催化剂催化氢氧直接合成过氧化氢的反应性能。结果表明：水热法原位合成制备的Pd-SiO_2催化剂,Pd颗粒分散较好,其尺寸范围为10～20 nm;对直接法催化合成过氧化氢反应,水热法原位合成制备的Pd-SiO_2催化剂的催化性能明显优于传统浸渍法制备的Pd/SiO_2催化剂,这是由于调节前驱液的pH值可减少催化剂的表面强酸量,有利于提高过氧化氢的稳定性。

Prepared Pd-SiO_2 catalysts in situ with hydrothermal method,which can control the diameter of active component Pd particle effectively,and the catalysts qualified with large pore volume and a certain amount of acid sites on the surface. The properties of catalysts were controlled by adjusting the p H of mixture in the preparation process. The structures and surface properties of the catalysts were determined by TEM,XRD,nitrogen adsorption and NH_3-TPD,and the catalytic performance of the Pd-SiO_2 catalysts in the direct synthesis of hydrogen peroxide from hydrogen and oxygen was investigated. The results showed that the Pd particles dispersed better,whose sizes distributed at 10-20 nm. For the direct synthesis of hydrogen peroxide from hydrogen and oxygen, the Pd-SiO_2 catalysts prepared in-situ performed better than the Pd / SiO_2 prepared with traditional impregnation method,it can be contributed by decreasing the amount of strong acid on the catalyst surface with adjusting the p H value of precursor solution,which improved the stability of hydrogen peroxide.