Synthesis And Catalytic Properties Of High Dispersion Supported Pt Reforming Catalysts From Hydrotalcite Precursor

Naphtha catalytic reforming is an important part of the oil industry.It can produce high octane number gasoline,light aromatic hydrocarbon and high purity hydrogen.Reforming reaction is very complicated,including dehydrogenation reaction,isomerization reaction,aromatization reaction,hydrogenolysis reaction and hydrocracking reaction.In the research of naphtha catalytic reforming,how to control selective evolve as a research hotspot.Supported Pt reforming catalyst,as a kind of important catalyst naphtha reforming.In naphtha reforming,supported Pt reforming catalyst is very important.The structure of the active centers in the catalyst,it directly affect the catalytic performance.How to more effectively control the structure of the catalyst activity center becomes the key to improve the catalytic performance problem.In this paper through the hydrotalcite precursor method to design a kind of active center high dispersion of Pt catalyst,It is applied to the n-heptane reforming reaction.Improve the selectivity of isomerization product,reduce selectivity of the aromatization product,and low selectivity of hydrogenolysis product,The specific research results are as follows.(1)The metal ions in the hydrotalcite layer is can be exchanged,and homogeneous dispersion in the hydrotalcite layer.Use in situ growth method,Hydrotalcite growth on the surface of Al2O3,Ga introduced to hydrotalcite layer.Get catalyst precursor MgAlGa-LDHs/Al2O3.Through XRD and SEM proved hydrotalcite layer has grown on the surface of Al2O3.Lattice parameters a increase,prove Ga3+ into the lattice of hydrotalcite.TPR、XPS、NMR proved Ga3+ is confined by the lattice of hydrotalcite,in the process of hydroxide into oxide by calcine.(2)Use incipient wetness method impregnate Pt to MgAlGa-LDHs/Al2O3 surface.After the calcination and reduction get catalyst Pt/MgAlGa-LDHS/Al2O3.Use HADDF-STEM and H2-O2 titration prove Pt dispersity and the proportion of single atom is high than PtGa/MgAl-LDHs/Al2O3 and PtGa/Al2O3.TPR、XPS、CO-FTIR proved Pt strongly interacting between Ga in Pt/MgAlGa-LDHs/Al2O3.Pt induced by Ga in hydrotalcite layer,showed higher dispersity and the proportion of single atom.(3)Use the active center dispersion from high to low of the catalysts,Pt/MgAlGa-LDHs/Al2O3,PtGal MgAl-LDHs/Al2O3 and PtGa/Al2O3 in n-heptane reforming reaction.Pt/MgAlGa-LDHs/Al2O3,the highest dispersion of catalyst,showed higher isomerization selectivity than other catalyst.After 480 min isomerization selectivity reach 52.8%.Aromatization product also has been effectively reduced,after 480 min aromatization selectivity reduced to 12.5%.All three catalysts showed lower hydrogenolysis selectivity,after 480 min hydrogenolysis selectivity still below 3.6%.Due to hydrotalcite compounds modified Al2O3,Al2O3 surface acidity was reduced.Effectively suppresses the hydrocracking reaction,hydrocracking selectivity reduced from 40%(PtGa/Al2O3)to 20%(Pt/MgAlGa-LDHs/Al2O3 and PtGa/MgAl-LDHs/Al2O3).