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Combined Extraction-Oxidation System For Oxidation Desulfurization (ODS) Of Fuel

Posted on:2016-05-25Degree:MasterType:Thesis
Country:ChinaCandidate:Y J TianFull Text:PDF
GTID:2271330485952327Subject:Applied Chemistry
Abstract/Summary:PDF Full Text Request
An efficient extraction-oxidation catalytic system for deep desulfurization of model fuel was explored. A Mo/γ-Al2O3 was prepared by impregnation method and characterized by X-ray diffraction(XRD), Temperature-programmed reduction(H2-TPR) and N2 physical adsorption isotherms. The result exhibited the characteristic of mesoporous structure and revealed that Al2(MoO4)3 might be more preferred for sulfur oxidation. Acetonitrile, methanol, N,N-Dimethylformamide, N-Methylpyrrolidone and H2O were added to investigate influence of extracting agents for extraction-oxidation desulfurization. Employments of acetonitrile and methanol showed synergistic action and improvement of DBT removal. Nevertheless, the extraction process is the main contribution to sulfur elimination using N,N-Dimethylformamide and N-Methylpyrrolidone as extractants. A detailed parametric study was performed varying n(H2O2)/n(S) molar ratio, v(oil)/v(acetonitrile), temperature, molybdenum loading, catalyst amount and sulfur species, to investigate their effects on desulfurization. Under n(H2O2)/n(S) molar ratio of 2.3,0.20 g catalyst and v(oil)/v(acetonitrile)=3:1, benzothiophene, dibenzothiophene and 4,6-dimethyldibenzothiophene could be almost completely removed over 16 wt% MO/γ-Al2O3 catalyst in 40 minutes at 60℃.A mechanism based on extraction-oxidation was proposed that sulfur compounds were transferred to extracting phase firstly and then oxidized to sulfones in the extracting phase. Extraction process was demonstrated to be quick step compared with the oxidation. The advantages of the extraction-oxidation catalytic system are that high removal rate of sulfur could be achieved under low n(H2O2)/n(S) and the stability of the catalyst was improved significantly in this case. The oxidation desulfurization reaction followed the first order kinetics.The oxidation of thiophene in model gasoline with heterogeneous Fenton-like system has been investigated to develop a novel oxidative desulfurization process. A series of different metal elements supported bimetallic catalyst were prepared and screened for catalytic oxidation of thiophene with H2O2 as oxidant and H2O as extraction agent. Based on the conversion of thiophene, CuO-Fe2O3/γ-Al2O3 showed the highest oxidative desulfurization activity. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction and Scanning electron microscope (SEM). The influences of the Fe and Cu loading in catalyst, reaction temperature, catalyst dosage, concentration of H2O2, initial concentration of thiophene on oxidative desulfurization activity were investigated, respectively. Under the conditions of temperature 60℃, catalyst dosage 0.2 g, n(H2O2)/n(Thiophene)=7.40 and reaction time 120 min,95.3% conversion of thiophene was achieved.
Keywords/Search Tags:Mo, heterogeneous Fenton-like system, catalytic oxidation, extraction, hydrogen peroxide
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