Study On Preparation And Performance Of Catalysts For Selective Transformation Of Mixed Propane And C₄ Hydrocarbons

Mixed propane and C₄ hydrocarbons are byproducts of Lurgi coal-based olefin （MTP） process. How to use them well has been paid urgent attention.In this work, considering reaction mechanism of mixed propane and C₄ hydrocarbons to olefins, multifunctional catalysts were designed and prepared to provide the catalytically active sites for the conversion of such mixed feedstock. Their activity were evaluated. The relationship between structure and properties of the catalysts was discussed by means of characterization of phase, porosity and acidity. These results provide usful clues for the utilization of mixed byproduct of hydrocarbons.Employing dual-amine hydrothermal synthesis and sol-gel process, composite catalysts of SAPO-11 wraped γ-Al2O3 and γ-Al2O3 wraped SAPO-11 in mass ratios of 1:3,1:1 and 3:1 were prepared, respectively. At set reaction conditions of space velocity（15g-h/mol）,600℃ and 0.1MPa, the catalytic activity of γ-Al2O3/SAPO-11 series for the transformation reaction of mixed hydrocarbon feedback is higher than that of SAPO-11/y-Al2O3 series.3y-Al2O3/SAPO-11 sample showed the best activity. The conversion of C30, i-C₄0, n-C₄= and n-C₄0 of mixed feedback was 14.71%,10.32%,24.58% and 16.85%, respectively. The selectivity of C2=+C3= in the products was 12.77%. The propylene/ethylene （P/E） ratio was 5.53. The selectivity of cis-2-C₄=+trans-2-C₄= was 75.90%. The selectivity of C1+C20 and C5+ was 5.37% and 5.96%, respectively. Developed catalysts improve the synchronous transformation of mixed hydrocarbon feedback. The selectivity of 2-butene showed high while C5+ low, relating to weak acidity of SAPO-11 and controlled extent of cracking.The composite catalysts were modified by WO3 and V2O5, respectively, and used in the tansformation of mixed feedback. The activity of 10%V205/3y-Al203/SAPO-11 sample highlighted. The conversion of C30, i-C₄0, n-C₄= and n-C₄0 of mixed feedback was 1.93%,12.81%,22.99% and 18.37%, respectively. The selectivity of C2=+C3= in the products was 12.41%. The P/E ratio was 5.51. The selectivity of cis-2-C₄=+trans-2-C₄= was 78.42%. The selectivity of C1+C20 and C5+ was 4.39% and 3.84%, respectively. The conversion of C₄ alkanes was increased obviously and the selectivity of C5= decreased, too. The conversion of propane was noticeably decreased. The modification of metal oxides needs further optimization.With CO2 coupled in mixed feeback （oxidative dehydrogenation conditions）, vanadium modified SAPO-11/γ-Al2O3 showed superier catalytic activity than of modified γ-Al2O3/SAPO-11. On 10%V2O5/SAPO-11/3y-A12O3, the conversion of C30, i-C₄0, n-C₄= and n-C₄0 of mixed feedback and the conversion of CO2 was 6.45%,10.35%,28.29%,23.66%, and 25.11%, respectively. The selectivity of C2=+C3= in the products was 10.19%. The P/E ratio was 1.97 due to remarkable increase in C2-selectivity. The selectivity of cis-2-C₄=+trans-2-C₄= was risen to 79.91%. The selectivity of C1+C20 and C5+ was risen to 7.73% and decreased to 2.16%, respectively. It is presumed that product of C3= is deeply oxidized.