| Low temperature coal tar can be transformed into fuel oil by catalytic hydrogenation due to its similar properties to heavy oil fractions, and it is an effective measure to decrease china’s high degree of dependence on foreign petroleum. Optimizing the reaction process and developing the special catalysts are core work of upgrading coal tar, and can lay the foundation for producing clean fuel oil.Naphthalene was chosen as the typical model compound of aromatics in coal tar. The influence of reaction conditions on the conversion of naphthalene and selectivities of products are investigated over commercial WMoNiP/y-Al2O3catalyst in a fixed bed reactor. The optimized process conditions of naphthalene hydrogenation are at320℃,4MPa, hydrogen to oil ratio of600:1and liquid hoursly space velocity of2h-1. The effect of heteroatoms was also studied by adding dibenzothiophene (DBT), quinoline and o-cresol respectively. The results reveal that heteroatoms play a negative role on aromatics hydrogenation. NiMoP/γ-Al2O3hydrofining catalyst with Ni content of lwt%～6wt%and NiMo/γ-Al2O3-β hydrocracking catalyst with different support are prepared by incipient wetness impregnation. The activities of the catalysts are investigated using o-xylene,1-methylnaphthalene and phenanthrene, and optimal catalysts grading combination was screened. By comparison, hydrofining-hydrocracking reaction process may be the rational technology for coal tar hydrogenation.Coal tar distillate hydrogenation was implemented over NiMoP/y-Al2O3(Ni=4wt%) hydrofining catalyst and NiMo/γ-Al2O3-β (Support:β=20wt%) hydrocracking catalyst. The results reveal that the main products of low temperature coal tar hydrofining are alkylnaphthalenes, while that of hydrocracking are alkylbenzenes. By catalytic hydroprocessing, S and N content in coal tar decreased to50ppm and12ppm respectively, and the H/C molar ratio increased to1.55, which showed great hydrogenation activity of the catalyst. |
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