Study On The Kinetics Of Alkylation Desulfurization Of Hydrocarbon Pyrolysis C9 Fraction

C9 fraction is the by-products of catalytic reforming and ethylene cracker, it is considered as a kind of petroleum resin raw material. Recently, it was studied for use as a gasoline additive to enhance the economic benefits.. However, C9 fractions are getting higher in sulfur contents, about 250 mg.L-1. According to these situations, C9 fraction desulfurization is receiving attention for the increasing stringent regulations on sulfur content.As the conventional hydrotreating technology results in a significant reduction of octane number due to saturation of olefins in naphtha from fluid catalytic cracking, which also causes higher hydrogen consumption. Consequently, many approaches to deep desulfurization have been proposed.Among the non-hydrodesulfurization technologies, the alkylation desulfurization is a rather attractive way. This approach consists in increasing the molecular weight of sulfur compounds using a catalytic alkylation reaction and hence in elevating their boiling point, thus allowing sulfur compounds to be easily separated by distillation. Therefore, the loss of octane number caused by the saturation of olefins during the hydrotreating could be alleviated. This technology has the advantage of green environmental protection, and could be operated at atmospheric pressure using solid catalysts.In this paper, I selected the 2-Ethylthiophen, 2,5-Dimethylthiophene and 2-n-Propylthiophene as the model compounds.The activity of solid phosphoric acid catalysts and macroporous sulfonic resins(including NKC-9, Amberlyst 35 and Amberlyst 36) were evaluated in simulative C9 fractions and real C9 fractions respectively, and the influence of temperature and distribution of sulfides was also studied. Results showed that resins had better activity than solid phosphoric acid catalysts. Among them, Amberlyst 36 resin showed good desulfurization efficiency(conversion of thiophenic compounds were above 93%) after 1 hour reaction under the temperature range of 70~110? while the weight ratio of catalyst and C9 fractions was 1:30.On the basis of activity evaluation, the influence of two kinds of active olefins(including isomalyene and vinyltoluene monomer) on the stability of catalysts was studied in C9 fraction.It was found that vinyltoluene monomer had a better effect on the alkylation desulfurization than isoamylene, that it has higher conversions, and with less time to reach the equilibrium. Moreover, in the text, kinetics of alkylation of sulfuric compounds over Amberlyst 36 were researched, and the kinetic equations were found. The alkylation of thiophenic sulfurs could be described as pseudo first order reaction, as well as the reaction rate constant and the activation energy of alkylation reactions were calculated.