Research On The Performance Of NiMo Catalyst In Coke Oven Gas Hydrodesulfurization

Coke oven gas is often used as fuel and chemical raw material.The deep processing of chemical raw materials has the best economic benefits.(synthetic methanol,ammonia,natural gas,oil,ethylene glycol,etc.).Besides the main components H₂,CH₄,CO,etc.,the coke oven gas also contains different forms of sulfide such as H₂S,CS₂,COS,RSH,C₄H₄S,etc.Its existence will cause poisoning and deactivation of various catalysts in the gas deep processing process,and the deactivation catalysts cannot be renewable,so coke oven gas must be deeply desulfurized before synthesizing chemicals.Among all the sulfides,the thiophene structure is the most stable and toxic to the catalyst.It is one of the most difficult to remove.Therefore,the main problem facing the deep processing of coke oven gas is the deep removal of thiophene.The traditional dry and wet desulfurization process is difficult to remove thiophene in coal gas to the requirements of industrial gas.For its deep removal,hydrodesulfurization(HDS)process must be used.The performance of the hydrogenation catalyst is critical in the HDS purification process.Industrial hydrodesulfurization catalysts are mainly Ni(Co)Mo/Al₂O₃.However,its HDS activity is low,and its operating temperature is high.During the reaction,the catalyst surface is prone to coking and carbon deposition,which reduces the service life of the catalyst.It is easy to generate by-products such as COS and CH₄,and the product selectivity is low.It is not conducive to the effective removal of sulfide during the desulfurization process.In view of the problems in the use of catalysts in the hydrodesulfurization process,the catalyst carrier and the optimal active metal loading were determined in this paper.On this basis,different additives were used to modify the industrial Ni Mo/Al₂O₃ hydrodesulfurization catalyst Sex study.The device in fixed bed micro examines the modified catalyst of thiophene in coke oven gas HDS performance,the effects of the use of specific surface area and pore size analyzer(BET),X-ray diffraction(XRD),temperature programmed reduction(H₂-TPR),X-ray photoelectron spectroscopy(XPS)on the catalyst characterization,such as intrinsic properties and focuses on the catalyst activity and selectivity,the relationship between the specific research contents and conclusions are as follows:1.Two different hydrogenation catalysts were prepared by using Al₂O₃ and Ti O₂ as supports and loading different amounts of metal active components Mo,respectively.The optimum Mo loading on Al₂O₃ carrier was determined to be 15wt.%.When the metal loading increases,the HDS activity of the catalyst decreases;when the Mo content on the Ti O₂carrier is 25wt.%,the catalyst activity is highest.The HDS activity of the catalyst prepared with Ti O₂ as the carrier is much greater than that of Al₂O₃,and the H₂S selectivity in the product is high.However,the surface area of the catalyst prepared with Ti O₂ as a carrier is much smaller than that of Al₂O₃and the methanation reaction is higher.2.The modification of Ni Mo/Al₂O₃ catalyst was carried out by different metals(Mg?Ca?Sr?Ba?La?Ce?Fe?Co?Ni).It was found that except for the introduction of Fe and Ni catalysts,the activity of other metal additive modified catalysts at low temperature HDS increased.After characterization,it was found that the acidity of the surface of the metal-modified catalyst changed greatly,the amount of strong acid increased,and the increase of acidity played an important role in the low-temperature hydrogenation performance of the catalyst.3.Five different phosphorus(1wt.%P)addition methods were prepared to modify Ni Mo/Al₂O₃ catalyst.Among them,the weak adsorption and dissociation active sites on the surface of the catalysts PNi-Mo/Al and PMo-Ni/Al are enhanced,and thiophene in coke oven gas has good low-temperature hydrodesulfurization activity.The conversion of thiophene HDS reached 61%and 54%at 250?.The HDS activity of the catalyst is high because these two P addition methods weaken the interaction between the active metal component Ni Mo and the support.The uniform dispersion of Ni Mo on the surface of the carrier is improved,and Ni Mo O₄species that can promote the vulcanization of the catalyst to form the type II active phase Ni-Mo-S are generated.The synergy between Ni Mo O₄ and Mo O₃improves the degree of sulfidation of the catalyst,resulting in enhanced HDS activity.