Co-Ru／γ-Al2O3催化剂的F-T合成性能

Catalytic Performance of Co-Ru/γ-Al_2O_3 Catalyst for Ficher-Tropsch Synthesis

以NH_4NO_3水溶液预处理的γ-Al_2O_3为载体,采用浸渍法制备了Co/γ-Al_2O_3催化剂,考察了添加少量贵金属Ru对Co/γ-Al_2O_3催化剂F-T合成性能的影响。实验结果表明,添加Ru可作为氢溢流源促进Co物种的还原,另外,Ru与Co相互作用形成易还原的Co-Ru物种,导致催化剂表面Co物种的还原温度降低,Co物种容易还原,反应过程中可利用的表面金属Co原子数增加;Ru可增加Co/γ-Al_2O_3催化剂表面桥式CO吸附的强度,使CO便于离解;添加少量Ru能明显提高Co/γ-Al_2O_3催化剂的活性和重质烃C_5^+的选择性。在原料气n(H_2):n(CO)=2.0、反应温度493K、压力1.5 MPa、气态空速500 h^(-1)下,15.0%Co-0.4% Ru/γ-Al_2O_3催化剂上CO的转化率和C_5^+的选择性分别为85.39%和84.28%。

Co/γ-Al2O3 catalyst for Ficher-Tropsch synthesis was prepared by impregnation usingγ-Al2O3 pretreated with NH4NO3 aqueous solution as support. Effect of adding small amount of noble metal Ru on performance of catalyst was studied. The added Ru acts as source of hydrogen spillover to promote reduction of cobalt oxides. Ru interacts with Co to form easily reducible Co-Ru species, which lowers reduction temperature of Co species on catalyst surface, and subsequently increases amount of available surface Co atoms during reaction. Ru enhances adsorptive strength of bridge-form CO, which facilitates CO to be dissociated. The addition of small amount of Ru can remarkably rise activity of catalyst and selectivity to heavy hydrocarbon. Under the conditions of n （ H2 ） ： n （CO） 2.0, 493 K, 1.5 MPa, 500 h^-1 and 15.0% Co-0.4% Ru/T-A12 03 as catalyst, CO conversion and selectivity to C5 are 85.39% and 84.28% respectively.