Study On Mechanism Of Adsorption Desulfurization In Microscale Pore

As The main reason of acid rain in the atmosphere, SOx is caused by buring organic sulfur in fuel oil. It can also lead to irreversible poisoning of the catalyst conversing automobile exhaust which significantly reduce the conversion efficiency of nitric oxide, incomplete combustion of hydrocarbon and particle, then the environment got severe polluted. Owing to mild reaction conditions and low operating cost, adsorption desulfurization process plays an important role in clean gasoline production.In this paper, the PTMAB and Al13 are prepared as pillared agent to gain inorganic-organic pillared montmorillonite through sol-gel method. The adsorption was conducted with prepared adsorbent, using n-octane and thiophene as model gasoline. The adsorption capacity of PTMAB-Al-MMT was studied, and the factors of adsorption desulfurization were optimized. Thermal regeneration was used to treat the adsorbent, and the efficiency was studied with different reaction condition. The samples were characterized by XRD, NMR, FT-IR, N2-sorption and TG-DTA to investigate the adsorption mechanism and the differences of adsorbent structure before and after adsorption.The results show that the reaction time and temperature has an important effect on adsorption desulfurization process. The best adsorption condition is 1.5h,40℃. The adsorption capacity after regeneration obtained under the condition of 200℃,2h and N2 purging can reach 70% of the original capacity. The Pseudo-second-order kinetics shows that there are strength of sharing of electronic between PTMAB-Al-MMT and thiophene.The characterization results show that, the layer spacing of inorganic-organic modified montmorillonite is 4 times of Na-MMT. The surface area doubled while the pore volume increased to four times the original. Adsorption capacity of the adsorbent can reach 5.32mg/g. The adsorption mechanism was obtained:the pillared agent PTMAB is soft acid while thiophene is soft base. Soft acid and soft base have similar size and electronegativity which conduces effective orbital overlap and covalent bond formed. Similarly, Al13 is border acid and they also form relative stable covalent bond.