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The theoretical calculation about the catalytic mechanism of MCM-41 supported phosphoric acid (SPAM) in the alkylation desulfurization of fluid catalytic cracking (FCC) gasoline demonstrated that properly reducing the amount of effective acid on the surface was beneficial to further enhancing the catalyst performance. Based on the previously optimized preparation of SPAM (weight ratio of total acid/MCM-41 6:1, calcination temperature 773 K and weigh ratio of H 3 PO 4 /H 4 P 2 O 7 1:2.5), an improvement by diluting the concentration of mixed phosphoric acids in the impregnating solution was carried out in this work. The surface structure and catalytic behavior of improved SPAM were investigated by structural characterization and experimental verification, respectively. The results proved that decreasing the concentration of mixed phosphoric acids in the impregnating solution in the preparation of SPAM could effectively reduce the existing acid amount on the catalyst surface by increasing the catalyst crystallinity, and both the surface acid strength and the total acids amount of SPAM were reduced. Moreover, the catalytic activity and selectivity of improved SPAM for thiophenic sulfurs alkylation in the alkylation desulfurization were enhanced and the olefins polymerization reactions were suppressed to a lower extent. Besides, the theoretical calculation was verified by this study, which opened a particularly appealing opportunity for the application of SPAM in the industrial alkylation desulfurization of gasoline. [ABSTRACT FROM AUTHOR]

Abstract: Sulfur removal has received increasing attention in recent years primarily for environmental protection purpose. As an attractive technology in the case of gasoline, OATS (olefinic alkylation of thiophenic sulfur) proposed to separate sulfur compounds by distillation after being weighed down by alkylation with olefins in the feed. In this paper, alkylation reactions of thiophenic compounds were studied over solid phosphoric acid catalysts (SPAM and SPAS using MCM-41 and Silicalite-1 zeolite as supporters respectively) and macroporous sulfonic resins (including NKC-9, D005-2 and Amberlyst 35) with model gasoline and FCC (fluid catalytic cracking) gasoline. Results showed that macroporous sulfonic resins showed better performance than solid phosphoric acid catalysts under milder conditions in both feeds. Among the resins, Amberlyst 35 was the most suitable catalyst for the application of catalytic distillation for its good performance at the temperature range of 353–413K in FCC gasoline. However, the selectivity of isoamylene dimerization over Amberlyst 35 decreased with the temperature, which was harmful to the product yield and catalyst stability. Besides, different activity orders of solid phosphoric acid catalysts in model gasoline and FCC gasoline were explained by combining the acidic properties of the catalysts with the species of olefins in two feeds. [Copyright &y& Elsevier]