表面酸性对Ni/SiO_2-Al_2O_3催化剂催化1,4-丁炔二醇高压加氢性能的影响

通过浸渍法分别在Al(OH)_3和Al_2O_3中引入SiO_2,经焙烧后制备具有不同表面酸性质的SiO_2-Al_2O_3载体,以上述SiO_2-Al_2O_3及Al_2O_3为载体,采用等体积浸渍法制备Ni负载量为15%的Ni/SiO_2-Al_2O_3催化剂(分别为Ni/SA-1和Ni/SA-2)与Ni/Al_2O_3.采用N2物理吸附、Py-FTIR、NH3-TPD、XRD、H2-TPR和H2-TPD手段对催化剂进行表征,考察了表面酸性质对催化剂催化1,4-丁炔二醇高压加氢性能的影响.结果表明,SiO_2引入方式会影响Ni/Al_2O_3催化剂表面酸性质及活性组分Ni在载体表面的分散行为.在Al(OH)3中引入SiO_2时,Ni/SA-1催化剂不仅活性组分具有高分散度,而且表面具有丰富的L酸位点,L酸位点与Ni活性中心协同作用有效提高了催化剂的高压加氢性能.而在Al_2O_3中直接引入SiO_2时,SiO_2覆盖了Al_2O_3表面的L酸位点,催化剂活性组分分散度较低,表现出低的加氢活性.

Effect of Surface Acidity on Ni/Al2O3 Catalyst Performance for 1, 4-butynediol Hydrogenation

Al2O3 supports with different surface acidity were prepared by introducing SiO2 into Al2O3 and Al(OH)3 via impregnation method, respectively. Also, the Ni/Al2O3 and Ni/SiO2-Al2O3 catalysts with 15% Ni loadings were prepared by equal volume impregnation method. All the catalysts were characterized by N2 adsorption-desorption, pyridine-in situ fourier transform infrared (Py-FTIR), NH3-temperature programmed desorption (NH3-TPD), X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR) and H2-temperature programmed desorption (H2-TPD), etc. The effect of surface acidity on the catalytic performance of catalyst for the hydrogenation of 1,4-butynediol was investigated. The results show that SiO2 introduction way has great impacts on the dispersion of active component Ni and catalyst surface acidity. Ni/SA-1 catalyst, using Al2O3 support prepared by introducing SiO2 into Al(OH)3 and then calcination, showed high dispersion of active component and rich Lewis acid sites on the surface. The synergy of Lewis acid sites and Ni active sites made the catalyst show excellent activity in the hydrogenation for BDO synthesis. However, when the SiO2 was directly introduced onto the Al2O3 surface, the catalyst showed low dispersion of active component, few Lewis acid sites, and poor hydrogenation activity.