Study On The Modification Of Ni-based Hvdrogenation Catalyst

With high hydrogen storage density, and relatively low hydrogenation temperature, N-ethylcarbazole is expected to be used as an on-board hydrogen storage system, it is a promising hydrogen storage material.In this article, a series of nickel-based hydrogenation catalyst were prepared with Al2O3 as carrier, nickel as active ingredient, ten kinds of different metals as promoters. The effect of nickel loading, promoters and reaction conditions on the catalytic activity of the catalyst were investigated by the hydrogenation reaction of N-ethylcarbazole.(1) The effect of nickel loading and promoter loading on the catalytic activity of the catalyst were investigated. The results showed that the catalyst with nickel loading was 25%(by mass), lanthanum loading was 3%(by mass), has the highest activity.(2)With 25%Ni/3%La/Al2O3 as catalyst of N-ethylcarbazole hydrogenation, The effect of reaction conditions on the activity of Ni-based catalyst was investigated and the optimum operation condition obtained was:200 ℃,6MPa and 1.5g 25%Ni/3%La/Al2O3. Under this condition, lOg N-ethylcarbazole could absorb 0.289mol hydrogen and the conversion rate reaches 94.14%.(3) When promoter loading was 3%(by mass), nickel loading was 25%(by mass), catalyst 25%Ni/Al2O3 was modified by lanthanum, samarium, cerium, cobalt, molybdenum, tungsten, vanadium, copper, chromium and magnesium. The Research fond that La, Sm, W, Cr and Mg can improve the conversion of N-ethylcarbazole. other metal had little effects on the activity of the catalyst or even reduce its activity. In addition, the effect of the content of La, Sm, W and Cr on hydrogenation of N-ethylcarbazole has also been investigated. The results indicate that When the content of them are 3%, the effect of catalyst is best.(4) With 25%Ni/3%Sm/Al2O3 as the catalyst of N-ethylcarbazole hydrogenation, The effect of reaction conditions on the activity of Ni-based catalyst was investigated and the optimum operation condition obtained was:200℃,6MPa and 1.5g 25%Ni/3%La/Al2O3. Under this condition, lOg N-ethylcarbazole could absorb 0.288mol hydrogen and the conversion rate reaches 93.81%.(5)25%Ni/Al2O3 were modified by two kinds of promoters at the same time, fixed the loading of each promoter as 3%, investigated the modification effect of two promoters’total loading on 25%Ni/Al2O3 catalyst; Then fixed the total load of two promoters as 3%, investigated the modification effect of the ratio of the load of the two promoters on 25%Ni/Al2O3 catalyst. The results indicated that the modification effect of single promoters were better than dual promoters.(6)The kinetics analysis of N-ethylcarbazole over 25%Ni/3%La/Al2O3 catalyst and 25%Ni/3%Sm/Al2O3 catalyst find that in the initial stage of the reaction, the mass transfer resistance of the gas-liquid and liquid-solid interface can be ignored, the hydrogenation reaction is controlled by chemical reaction on the catalyst surface, hydrogenation reaction is controlled by chemical reaction on the surface of catalyst, under the temperature range of 180～220℃, at 3.0～7.0MPa on 0.5～1.5g catalyst dosage, The activation energy of N-ethylcarbazole hydrogenation over 25%Ni/3%La/Al2O3 catalyst is estimated to be 25.62 kJ/mol and the apparent kinetics equation is: robs=2.262 ×10-3 . e-2.562×104/RT.6m/ρpdp.CeThe activation energy of N-ethylcarbazole hydrogenation over 25%Ni/3%Sm/Al2O3 catalyst is estimated to be 10.58 kJ/mol and the apparent kinetics equation is: robs=2.572×10-3.e-1.058×104/RT.6m/⌒pdp.Ce...