Ni2 在炭包覆氧化铝表面存在状态及加氢性能

采用等体积浸渍法制备了以炭包覆氧化铝(CCA)为载体的Ni基催化剂.利用低温N2物理吸附、XRD、UV-Vis DRS、H2-TPR、H2-TPD等手段对催化剂进行表征,并考察了催化剂粗1,4-丁二醇加氢反应性能.结果表明,均匀分散在表面的炭可以有效阻止Ni2+进入氧化铝表面四面体及八面体空位,Ni2+以与载体具有中等强度相互作用的物种形式存在.随Ni含量的增加,镍物种晶粒尺寸发生明显变化,当Ni含量低于10%时,NiO以高分散状态存在于载体表面,Ni含量达到14%时催化剂中出现了NiO微晶,进一步提高Ni含量,NiO晶粒尺寸有所长大,但仍保持了较高的分散度.由于Ni的聚集程度较小,随着Ni含量增加,Ni的总活性比表面积增加,催化剂加氢活性提高,至Ni含量达17%时,催化剂表现出最佳的催化加氢活性.

Dispersion of Ni2 supported on Carbon Covered Alumina surface and Its Hydrogenation performance

Ni/CCA catalysts with different Ni loading were prepared by impregnation method used carbon-covered alumina (CCA) as support. The samples were characterized by N2 physisorption, X-ray diffraction, Ultraviolet-visible diffuse reflectance spectroscopy, H2 temperature-programmed reduction, H2 temperature- programmed desorption. And their catalytic performances were also investigated in the hydrogenation of crude 1,4-butanediol aqueous solution. The results showed that Ni loading less than 10%, NiO existed by amorphous or highly dispersed. When the Ni loading was 14%, trace amount microcrystalline NiO appeared. For the catalysts with Ni loadings higher than 14%, active surface area and catalytic performance increased with increasing Ni loading of the Ni/CCA catalyst. The 17Ni/CCA catalyst showed the excellent catalytic performance.