浸渍次序对钴基催化剂F-T合成催化性能的影响

Effect of Component Impregnation Sequence on Catalytic Performance of Ru-Co-ZrO_2/γ-Al_2O_3 Catalyst for Fischer-Tropsch Synthesis

采用浸渍法制备钴基催化剂,考察了催化剂组分浸渍次序对其F-T合成反应性能和产物分布的影响。载体γ-A l2O3先浸渍Zr组分,可阻止活性组分与载体间形成难还原的铝酸钴化合物。同时,ZrO2可与催化剂表面的金属Co形成活性界面,在一定程度上使CO容易离解,从而使催化剂呈现出较高的活性和重质烃选择性。在原料气n(H2)∶n(CO)=2.0、温度493 K、压力1.5 MPa、空速800 h-1下,载体先浸渍Zr,然后浸渍Co和Ru的混合水溶液,CO的转化率和C5+的选择性为82.54%和85.63%,链增长概率为0.86,3种组分分次浸渍,CO的转化率、重质烃C5+的选择性和链增长概率分别为81.03%、84.69%和0.83。三种组分混合浸渍,Co可能在催化剂浸渍、干燥、焙烧过程中与载体相互作用形成一定量的难还原化合物,使催化剂的催化性能下降。

Ru -Co -ZrO2/γ-Al2O3 catalysts are prepared by incipient impregnation method. The effects of component impregnation sequence on catalytic performance and product distribution for Fischer - Tropsch synthesis are studied. Zr component is impregnated with carrier γ-Al2O3 first, it might prevent active component and carrier from the formation of irreducible cobalt aluminate. Simultaneously ZrO2 can form active interface with metal cobalt on the catalyst surface, and make carbon monoxide be dissociated easily to some extend, so catalysts exhibit higher activity and the heavy hydrocarbon selectivity. Under the condition of feed gas n（ H2 ） ： n （CO） = 2.0, temperature 493 K, pressure 1.5 MPa and space velocity 800 h ^-1, carriers firstly impregnate ZrO2, then impregnate the mixture of Co and Ru aqueous solution, the con version of carbon monoxide , heavy hydrocarbon selectivity of C5^＋ and the chain growth probability is 82.54% ,85.63% and 0.86 respectively. While three components are impregnated in order, the conver sion of carbon monoxide , heavy hydrocarbon selectivity of C5^＋ and the chain growth probability is 81.03% ,84.69% and 0.83 respectively. Three components are impregnated with mixed aqueous solution, it is possible that cobalt species interact with carrier and form some amount of irreducible compound in the course of impregnation, performance of catalyst. drying and calcinations of catalyst, which led to the descent of catalytic