One-pot synthesis of the highly efficient bifunctional Ni-SAPO-11 catalyst

Hydro isomerization of linear alkanes to branched isomers is an important petrochemical process for production of gasoline with high octane number.Non-noble metal bifunctional catalysts used in this process always suffer from low metal dispersion and poor metal-acid synergy.Herein,a facile one-pot synthesis method was used to simultaneously regulate metal particle sizes and acidity of the Ni-SAPO-11 hydroisomerization catalyst.The physicochemical properties are investigated using XANES,EXAFS,TEM/STEM,FT-IR,XPS,UV-vis and NH_3-TPD.Apart from the highly dispersed nickel nanoparticles with an average diameter of 8 nm,the framework Ni~(2+)ions are generated via substituting framework Al~(3+)ions of the SAPO-11.The formed NiP-OH structures have lower deprotonation energy(DPE)than the SiAl-OH ones,contributing more and stronger acid sites to the Ni-SAPO-11 catalyst.The great metal-acid synergy including high metal to acid sites ratio(n_(Ni)/n_A)and close intimacy is obtained for the Ni-SAPO-11 catalyst.The Ni-SAPO-11 catalyst outperforms the counterpart prepared by the impregnation method and exhibits comparable activity and isomers selectivity to the Pt/SAPO-11 catalyst in the n-hexane hydroisomerization.