Study On Ni-based Catalysts For Selective Hydrogenation Of Reformate To Remove Trace Olefins

The oil produced by catalytic reforming is rich in aromatic hydrocarbons and solvent oil fractions,and also contains a small amount of olefins.To produce qualified aromatic hydrocarbons and solvent oil products,the olefins must be removed.Selecting hydrogenation to remove trace olefins in the reformed oil has the characteristics of long operation cycle of the device and environmental friendliness.Large-scale refining and chemical enterprises are gradually adopting hydrogenation technology to replace the clay adsorption process.In this thesis,alumina supports with different calcination temperatures were prepared using aluminum hydroxide dry glue as raw materials,and NiO/Al₂O₃ catalysts with different supports and different NiO contents were prepared by an equal volume impregnation method.The analysis and characterization results of the prepared catalyst and support using BET、XRD、NH₃-TPD、Py-IR and TEM methods show that as the calcination temperature of the support increases,the specific surface area of the support and the catalyst decreases,the average pore diameter increases,and the changes of pore volume is not obvious;the carrier calcined at 550～750℃shows theγ-Al₂O₃ crystal form,and the carrier calcined at 850℃appears theδ-Al₂O₃ crystal form;the carrier and the catalyst have only L acid and no B acid sites.With the increase of carrier calcination temperature,the acid strength gradually weakened.On a 10 m L micro-reactor,the hydrogenation activity evaluation of the prepared catalyst with the reformed oil of Sinopec Qingdao Refining and Chemical Company as the raw material showed that with the increase of the carrier calcination temperature,the NiO/Al₂O₃ catalyst reformed to produce oil The olefin hydrogenation activity first increased and then decreased,and the aromatics loss first decreased and then increased.When the loading of NiO is less than 25%,as the loading of NiO increases,the bromine index of hydrogenation products gradually decreases,and the loss of aromatics gradually increases;when the loading of NiO is greater than or equal to 25%,as the loading of NiO increases,increase The bromine index of hydrogenated oil increases and the loss of aromatics decreases.When the NiO loading is greater than or equal to 35%,the bromine index of hydrogenated oil increases and the decrease in aromatics content decreases.Using lanthanum oxide modified NiO/Al₂O₃ catalysts,NiO/La₂O₃-Al₂O₃ catalysts with different lanthanum addition methods and different lanthanum oxide contents were prepared,and the catalysts were prepared by BET、XRD、NH₃-TPD、Py-IR and TEM.The analysis and characterization results showed that,With the increase of lanthanum oxide loading,the specific surface area and pore size decreased slightly,the pore volume remained basically unchanged,the crystallinity of NiO decreased,and the grain size first decreased and then increased.The evaluation results of the hydrogenation activity of reformed oil produced by the 10 m L microreactor showed that the olefin hydrogenation activity of the lanthanum-modified NiO/La₂O₃-Al₂O₃ catalyst was better than that of the NiO/Al₂O₃ catalyst.The hydrogenation activity of the modified catalysts modified by different lanthanum addition methods is lanthanum first and then nickel>co-impregnation method>nickel first and then lanthanum.The addition method of lanthanum has less effect on aromatics hydrogenation and greater impact on olefin hydrogenation.With the increase of lanthanum oxide loading,when the reaction temperature is lower than 100℃,the bromine index in the hydrogenated oil decreases,but the decrease is small;when the reaction temperature is greater than 100℃,the bromine index in the hydrogenated oil first decreases and then When the content of lanthanum oxide is 1%,the bromine index is the lowest,and the catalyst has better olefin hydrogenation activity.There is little change in the aromatic loss rate of different lanthanum oxide supported catalysts for hydrogenation to produce oil.The loading of lanthanum oxide has a greater impact on the olefin hydrogenation activity of the NiO/La₂O₃-Al₂O₃ catalyst than the aromatics hydrogenation.