Preparation Of Titanium Dioxide Support And Study On Properties Of Ni-Mo Hydrodesulfurization Catalyst

In recent years,with the development of coking industry in China,people begin to pay attention to the deep processing and utilization of coke oven gas.Coke oven gas can be used as chemical raw material to synthesize methanol,methane,chemical fertilizer and so on and it can increase its added value greatly,which is one of the ways of scientific utilization of coke oven gas.Coke oven gas contains H₂ S,COS,CS2,thiophene and other forms of sulfur,which will bring about deactivation of catalyst with Ni,Cu and Fe as active constituent.So It is necessary to convert organic sulfur to H₂ S and make sure total sulfur below 0.1ppm.At present,the industrial application of organic sulfur hydrogenation catalyst mainly uses ?-Al₂O₃ as support.But the hydrogenation catalyst supported on?-Al₂O₃ has a high operating temperature?about 350 ??,resulting in methanation,carbon deposition,and even the formation of thiol and thioether in the presence of COS and CS2.In recent years,people began to turn their attention to the hydrogenation catalyst with TiO₂ as support,which has Low temperature activity and less side effects.Because the specific surface area of traditional TiO₂ is only about 10m²/g,the activity of supported hydrogenation catalyst is low.In this paper,four kinds of TiO₂ supports with high specific surface area were prepared by hydrothermal synthesis and sol-gel method.The specific surface area and pore size analyzer?BET?,X-ray diffraction?XRD?and scanning electron microscopy?SEM?and other characterization methods were used to analys surface area,crystal structure and morphology of prepared TiO₂ supports and catalysts.And then,the hydrodesulfurization catalysts for nickel and molybdenum supported on TiO₂ and ?-Al₂O₃ catalysts by optimizing methods were evaluated under simulated coke oven gas atmosphere.Specific research contents and conclusions are as follows:1.With glycerol,ethanol and ether as raw materials,mesoporous Ti O₂ nanosheet-based hierarchial tubular superstructure?MTNHTS?synthesized by hydrothermal method.The effects of raw material ratio,reaction time and reaction temperature on the products were investigated.When glycerol: ethanol: diethyl ether is 20mL:40mL:20mL,and the reaction temperature is 160?,and the reaction time is 24 hours,the specific surface area of MTNHTS is up to 55m²/g.2.The ordered mesoporous TiO₂?OMT?was prepared by sol-gel method.The influence of the ratio of butyl titanate,P123,ethanol and hydrochloric acid on OMT was investigated.The results showed that when butyl titanate is 5g,P123 is 2.5g,ethanol is 37.5ml and hydrochloric acid is 8ml,the specific surface area of OMT is up to 154m²/g.3.TiO₂ nanotubes?TNT?with high specific surface area were synthesized by hydrothermal synthesis using Ti O₂ with low specific surface area and 10mol/L NaOH solutions.The effects of PH treatment,reaction temperature and reaction time on the products were investigated.The results showed that when PH is 7,and the reaction temperature is 170?,and the reaction time is 20 hours,the specific surface area of TNT is up to 119m²/g.4.TiO₂ nanometer materials?TAN?with high specific surface area were synthesized by hydrothermal synthesis using Titanic acid with low specific surface area and 10mol/L NaOH solutions.The effects of PH treatment,reaction temperature and reaction time on the products were investigated.The results showed that when the reaction temperature is 170?,and the reaction time is 24 hours,the specific surface area of TAN is up to 161m²/g.5.The catalysts were prepared by using ammonium molybdate as Mo source and six hydrated nickel nitrate as Ni source,and Ti O₂ optimized by the above four methods and ?-Al₂O₃ as supports.These catalysts were signed as NiMo/?-Al₂O₃,NiMo/MTN,NiMo/OMT,NiMo/TNT and NiMo/TAN.When the reaction conditions was normal atmospheric pressure,and reaction temperature was 200-380 ?,and space velocity was 2000h-1 and thiophene inlet concentration was 450 mg/m3,the conversion rate of thiophene for catalysts supported on TiO₂ was higher than that of NiMo/?-Al₂O₃ catalyst.The conversion rate of thiophene on NiMo/MTN and NiMo/OMT can reach above 99% at 300?;When the temperature reached 350?,the conversion rate on NiMo/TNT and NiMo/TAN catalysts were above 99%;When the temperature reached 380?,the conversion rate of thiophene on NiMo/?-Al₂O₃ catalyst was only 95%.