Document Type : Research Article
Authors
1
Process Engineering Department, Chemical Engineering Faculty, Babol Noshirvani University of Technology, Babol, Iran.
2
Assistant professor of Chemical Engineering Faculty in Babol Noshirvani University of Technology
3
Process Engineering Department, Chemical Engineering Faculty, Babol Noshirvani University of Technology, Babol, Iran.,
4
Separation Processes, Chemical Engineering Faculty, Babol Noshirvani University of Technology, Babol, Iran
Abstract
Adsorption capacity and selectivity are two fundamental challenges in which adsorption desulphurization faces. One way to overcome this challenge is to use mesoporous zeolites. In this study, the effects of mesoporosity on the adsorption desulphurization performance with mesoporous HZSM-5 zeolite adsorbents, which have been prepared by desilication operation in an alkaline environment using a NaOH solution at concentrations of 0.2 and 0.5 M, as well as a mixture of base solution NaOH/TPAOH (0.5 M) with molar ratios of R=TPAOH/(NaOH+TPAOH) =0, 0.2, 0.4, 0.6 at 75 ℃ for 2.5 hours were investigated and the results were compared with the parent microporous zeolite. The characteristics of prepared adsorbents were determined by XRD, BET, FE-SEM and FT-IR analyses. The results showed that different ratios of NaOH/TPAOH solution in desilication operations play an important role in adsorbing sulfur compounds. Compared with the parent microporous zeolite, the mesoporous HZSM-5 adsorbent with concentration of 0.5 M and molar ratio of TPAOH/(NaOH+TPAOH) =0.4 ensures the formation of narrow and uniform intracrystalline mesoporosity without severely damaging the crystal structure, which resulted in the best adsorption desulphurization performance, including the highest adsorption capacity of thiophene and dibenzothiophene with values of 16.6 and 6.7 mg/g, respectively. In this regard, the effect of temperature on this adsorbent on the adsorption of thiophene sulfur compound was investigated. The results showed that the adsorption of thiophene sulfur compound increases with increasing temperature and reaches a maximum of 18.4 mg/g at 65 ℃. Thermodynamic studies showed that the adsorption process is endothermic. Kinetic models of adsorption of sulfur compounds followed the pseudo-first-order equation (R2 = 0.99).
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