Catalytic Performance Of Supported Sulphates For Oligomerization Of Mixed Butene

Low carbon olefins are formed in significant quantities during petroleum processing,such as catalytic cracking（FCC）.Increasing the utilization of the byproduct olefins is an urgent problem to be solved in the development of chemical industry,and the research of oligomerization is the most important content in this field.The mixed butane oligomerzation products can act as the reaction materials and intermediates,since the oligomerization catalysts is the key to the utilization of mixed butane.In this thesis,a series of catalysts of MSO₄/γ-Al₂O₃（M for the Fe,Co,Ni,Al）catalysts were prepared by impregnation method.The influence of different sulphate style and sulphate loadings on the properties and catalytic performance of catalysts were investigated as well as the effect of reaction conditions on the activity and product distribution of catalysts.Meanwhile the effect of TiO₂ as promoter on the properties of catalyst prepared and catalytic performance are also investigated.Main results are given as follows.1.A series of catalysts of MSO₄/γ-Al₂O₃ catalysts with the 8wt%mental loading was prepared,while the NiSO₄ and CoSO₄ achived higher dispersion than Fe₂（SO₄）₃ and Al₂（SO₄）₃ on the carrier.There is a weak acid ammonia desorption peak at about 250℃of NiSO₄/γ-Al₂O₃ and Fe₂（SO₄）₃/γ-Al₂O₃ catalysts.The best catalytic performance for oligamerization of mixed butenes was obtained over 8wt%NiSO₄/γ-Al₂O₃ catalyst under the reaction conditions of P=4.0 MPa,LHSV=2.0 h^-1,T=72℃with the highest C₈⁼selectivity.The best catalytic performance for oligamerization of mixed olefins was obtained with 7wt%Fe₂（SO₄）₃/γ-Al₂O₃ catalyst.Comparing to the co-imregnation method,the Fe₂（SO₄）₃/γ-Al₂O₃catalyst with step-impregnation method showed more amount of weak acid center,better activity and,higher C₈⁼selectivity.The catalyst of NiSO₄/γ-Al₂O₃ was tested in the selective oligomerization reaction of mixed butene.The results showed that the conversion of 1（iso）-butene was not affacted by temperature and LHSV,but higher reaction temperature and lower LHSV were favorable for the conversion of Z（E）-2-butene,while the higher temperature and higher LHSV were beneficial to enhance C₈⁼selectivity.2.The weaker acid strength,less acid center number,lower specific surface area,as well as higher pore volume and pore size were obtained with the TiO₂ loading increase.The conversion of 1（iso）-butene was not affacted by the addiction of TiO₂.Under the reaction conditions of P=4.0 MPa,LHSV=2.0 h^-1,T=72℃,the best catalytic performance for oligamerization of mixed butenes was obtained over 5wt%Ti addiction with lower stability,while the activity of 5wt%Ti addiction catalyst were similar to the Ni SO4/γ-Al2O3 catalyst as well as the higher C₈⁼、C⁼₁₆、C₂₀⁼selectivity.The decrease of pore size and pore volume after reaction,which indicated that blocking holes is the influence of the activity of the catalysts.