Study On The Bimetallic Doped Solid Acid Catalyst Cu/Ga₂O₃/SO₄^2-ZrO₂ For N-butane Isomerization

Increasingly stringent environmental regulations are accelerating improvements in alkylation technologies of isobutane with olefins to produce sulfur-free gasoline with a high octane number.The isobutane can be produced by n-butane isomerization.So,it is necessary to innovate and develop catalysts for modern science and alkanes isomerization in commercial applications.Most of these industrial processes involve bifunctional catalysts consist of metal component for dehydrogenation and acidic support.Among them,the catalysts based on sulfated zirconia(SO42--ZrO2)demonstrate strong activity and thermal stability.So,in this work the SO42--ZrO2 was synthetized as support at first.Then,the catalysts preparation by loading non-noble metal Ga and evaluation conditions were optimized.The results show that both wetness impregnation and coprecipitation with a can inhibit ZrO2phase transformation from tetragonal to low activity monoclinic crystallite effectively.The suitable Ga content and calcination temperature is 3-5 wt.%and 700 ?,respectively.The suitable method is wetness impregnation,because the active Ga not only stabilizes the tetragonal ZrO2 as support,but also has significant effect on the acid strength rather than concentration.That is the strong Br(?)nsted acidic sites was emerging.After evaluation in a fixed bed reactor for 10 h,the suitable operation conditions are 250?,1.5-2 MPa,0.2-0.4 h-1 with the n(H2)/n(C4H10)molar ratio of 1.5-3.The catalytic performance is most sensitive to the reaction temperature.In order to upgrade the quality for n-butane isomerization,the effect of the second metal promoters was investigated.It is surprising that both n-butane conversion and thermal stability are improved by adding Cu rather than Pt and Pd with high intrinsic activity,which has a good application prospect.Because the H2 spillover was triggered by Cu,the polymerization of coke precursors was hindered,retarding the deactivation.The suitable Cu content and calcination temperature is 0.6 wt.%and 650-700? respectively.It is worth to further treat the fresh Cu/Ga2O3/SO42--ZrO2 catalyst in an air flow at 450?and adjust to 250-350? inside the reactor.When the temperature was obtained and stable,it was pretreated in a H2 flow prior to isomerization.At a TOS of 22 h,n-butane conversion is-55%and the selectivity to isobutane is above or equal to 80%at the suitable reaction temperature of 230-250?.