Study On The Physi-Sorption Desulfurization Of FCC Gasoline

Absorption of sulfur-contaminated compounds is a new technology for removal of organic sulfur compounds because of its high performance and relatively low capital and operational costs. The technology is recognized in refinery industry. The physi-sorption rather than chemi-sorption is provided with the easy operation conditions while the content of sulfur in Fluid Catalytic Cracking (FCC) gasoline can be reduced by a half. The technology is suit for China refinery. Active charcoal, molecular sieve 13X, molecular sieve Y which supported a certain metal, kaoline (the superficial area over150 m2/g) and γ-Al2O3 can physically adsorb some organic sulfur compounds in FCC gasoline. The study on the static test of adsorption shows that active charcoal and molecular sieve 13X can adsorb more organic sulfur compounds in FCC gasoline. The study on the dynamic test of adsorption shows that molecular sieve 13X and molecular sieve Y which supported a certain metal can adsorb more organic sulfur compounds in FCC gasoline under same operation conditions. The optimized adsorption operation conditions for molecular sieve 13X: Temperature of the adsorption bed is 200 to 230 ℃; Pressure is about 0.3 MPa; The feed rate of the liquid gasoline is about 1.0/h. The sulfur content in FCC gasoline is significantly reduced while gasoline recovery is high without the octane number loss. These main properties of the gasoline are not been changed by the adsorption as well. After the study of some factors which influence desulfurization effects with molecular sieve 13X, the conclusions can be reached: 1) Low temperature is benefit for the adsorption with the less investment as well. 2) Low feed rate is benefit for the desulfurization, but the capacity is low. 3) High pressure is benefit for the desulfurization. The B.E.T equation can be described the curve of adsorption when the temperature is not changed. The adsorption belongs to layer upon layer.