Mesoporous SBA-16 Hydrodearomatization Catalyst Modified By Graphene、HY

With the increase of diesel fuel consumption and the tightening of environmental protection regulations in China,the requirement for the content of aromatic hydrocarbons in automotive diesel is also more stringent.The hydrodearomatization process is an effective way to produce clean diesel,meanwhile,the key is to develop high-performance hydrodearomatization catalysts.The mesoporous molecular sieve SBA-16 is often used as a catalyst support for its large pore size and high specific area,however,it has the disadvantages of low acidity and weak adsorption as a pure silicon-based material,which limits its application in the field of hydrodearomatization.In this paper,mesoporous molecular sieve SBA-16 is used as a carrier,which is modified by graphene and microporous molecular sieve HY,then study on hydrodearomatization reactionthen after loading NiO.Graphene oxide（GO）was prepared by the Hummers,and we introduced different amounts of GO into surface of mesoporous molecular sieve SBA-16,and prepared a composite materials GO（m）-SBA-16（m=0.05,0.1,0.2）of graphene oxide and mesoporous molecular sieves SBA-16,then we obtained catalyst NiO/RGO（m）-SBA-16（m=0.05,0.1,0.2）after loading the active component Ni calcineded under the protection of N₂,（RGO is reduced graphene oxide）,and We further explored the effect of the introduced amount of graphene on the activity and selectivity of the catalysts.The microporous molecular sieve HY was introduced into the SBA-16mother liquor during the hydrothermal synthesis process,we prepared the composite molecular sieve HY（n）-SBA-16（n=0.03,0.06,0.12）of microporous molecular sieve HY and mesoporous molecular sieves SBA-16,then we obtained the catalyst NiO/HY（n）-SBA-16（n=0.03,0.06,0.12）after loading the active component Ni,and We further explored the effect of the introduced amount of HY on the activity and selectivity of the catalysts.The structure and properties of catalysts NiO/RGO-SBA-16 and Ni/HY-SBA-16 were characterized by XRD、FT-IR、NH₃-TPD、H₂-TPR、SEM and other methods.Use dodecane solution with 5%naphthalene as hydrogenation simulation diesel to investigate the hydrogenation catalytic performance of the catalyst.The main results and conclusions are as follows:1.The characteristic of theπ-πoverlapping adsorptionthe between largeπbond of graphene with aromatic rings of naphthalene and tetralin can promote the hydrogenation of naphthalene and tetralin when combining GO with mesoporous molecular sieves SBA-16.The excess graphene introduced will have a certain covering effect on the surface of SBA-16,and obstruct the diffusion of naphthalene and tetralin into the channels of SBA-16,which affects the progress of the hydrogenation reaction in the channels,resulting in reduced total hydrogenation activity.When GO/（GO+SBA-16）=0.1,the catalyst NiO/RGO（0.1）-SBA-16 not only can ensures the hydrogenation reaction in the SBA-16 channel,but also can use the adsorption characteristics of the graphene to naphthalene and tetralin,the conversion rate of naphthalene and the selectivity of decalin are the highest,up to 99.71%and 99.80%,respectively.2.The catalyst NiO/HY-SBA-16 has micropores and mesopores channels,the introduction of HY increases the specific area of the catalyst,besides,the increases of acidic adsorption center of the catalyst slows the competitive adsorption between the naphthalene and tetralin in the metal active center;moreover,the formation of overflowing hydrogen promotes the hydrogenation reaction of naphthalene and tetralin at the acid adsorption center;The excess HY introduced will lead to a decrease in the average pore size which will inhibit the diffusion of aromatic hydrocarbons,while excess acidity will cause side reactions such as isomerization and cracking of naphthalene in the acid center,which will reduce the selectivity of the target product decalin.when HY/SBA-16=0.06,the catalyst NiO/HY（0.06）-SBA-16has the optimal catalytic behaviour,the conversion rate of naphthalene and selectivity of decalin can reach 99.74%and 99.41%,respectively.