Study On The Heavy Benzol Distillates Hydrogenation Catalysts Preparation And Model Compounds Hydrogenation Process

Heavy benzol is the by-product of crude benzene hydrofining process, which yield is about 10%(weight percent) of crude benzene.At present, this resource fails to get good utilization and the heavy benzol products in most coke-making plants in China are black-brown in appearance with severe offensive odor and there are a lot of unsaturated compounds, which have influenced the further process, utilization and their commercial values. The hydrofining process of unsaturated compounds in heavy benzol was studied in this paper. We hope to obtain stable compounds by hydrogenation.In this study by means of atmospheric distillation, we divided heavy benzol into four fractions with boiling points range respectively 150-160℃,160-185℃, 185-200℃and above 200℃. GC, IR and GC-MS were adopted to analyze the components and contents of the 160-185℃fraction of heavy benzol.In this paper a series of Ni/γ-Al2O3 catalysts with different nickle contents and catalyst samples with Ni content 8%and promoter Mo contents 1%-5% were prepared by means of impregnation method.The catalysts were characterized by XRD,BET,SEM and EDS.The effect of properties on catalytic activation for hydrogenation of model compounds was studied.The catalysts with different nickel contents were selected in an autoclave, and the nickel 8%content was suitable. Then the catalysts which the amount of promoter Mo was different on hydrogenation were studied. Finally the catalyst which Ni content was 8%and Mo content was 2%was used to study hydrogenation process in model compounds.The hydrogenation of model compounds and the fraction 160-185℃of heavy benzol were investigated in an autoclave, and GC was adopted to analyze the components and contens of the products. The compositions of heavy benzol were complicated and literatures were few. The 160-185℃fraction of heavy benzol was hydrogenated based on the unsaturated model compounds. The investigations were concentrated reaction temperature, reaction time, H2 pressure and catalyst dosage etc. on the hydro-upgrading process. Then we selected an optimal condition to study the hydrogenation of the fraction 160-185℃of heavy benzol.The results indicated that:(1)The materials used in this experiment was secondary heavy benzol(Y B/T2303-2005).The fraction under 200℃was 36.4%in heavy benzol.And the initial boiling point was 156.9℃. The main components of the 160-185℃fraction of heavy benzol arc indcne, styrene,1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene naphthalene, benzofuran,which the amounts are 31.88%,24.52%,10.63%,8.38%,7.75%,6.26%,respectively.The indene and styr-ene both contain unsaturated bonds which the amounts are 56.4%.(2)The specific surface, pore volume and mean aperture of nickel catalysts reduced with the increase of nickel contents.The NiO phase appeared when the nickel content was 8%by XRD and it increased with the increase of nickel contents.That indicated the aggregation of NiO incrased.(3)The dispersity of catalysts improved when the promoter Mo was added.The NiO phase reduced with the increase of promoter Mo contents when the nickel content was 8%. The specific surface, pore volume and mean aperture of NiMo catalysts were larger than those of nickel catalysts when the Mo contents were from 1%to 2%.However the indexes of catalysts reduced when the Mo contents were from 3%to 5%.(4)Then the selected catalyst which nickel content was 8%and molybdenum content was 2%was used in an autoclave to optimize the reaction conditions. we discussed the influence of reaction temperature,reaction time,H2 pressure and catalyst dosage to the conversion of styrene and the yield of ethylbenzene. The conversion of styrene was over 99.7%and the the yield of ethylbenzene was over 99.1%, when reaction temperature was 150℃,reaction time was 15min,H2 pressure was 5MPa and catalyst dosage was 2 wt%of oil.(5)Finally the hydrogenation of the 160-185℃fraction of heavy benzol was studied in the paper. The conversion of styrene was 85%and the yield of ethylbenzene was 79.6%, when reaction temperature was 150℃, reaction time was 15min,H2 pressure was 5MPa and catalyst dosage was 2 wt%of oil.It showed the hydrogenation process condition is applicable to the 160-185℃fraction of heavy benzol according to the model compounds.However we need further study in view of the unsaturated components which include styrene, benzofuran etc.