were synthesized and characterized by elemental analysis, X-ray diffraction, and infrared spectra, meanwhile their catalysis in an extractive catalytic oxidative desulfurization process was studied with ionic liquid (IL) as extractant and H 2 O 2 as oxidant. The main factors affecting the desulfurization process were investigated, including temperature, hydrophobicity of IL, and variety of S-compounds, as well as the amount of catalyst, IL, and H 2 O 2 . Under the optimal conditions, the S-content of DBT oil can be decreased from 1000 to 2 ppm. A new interpretation is proposed for the current process, in which IL is assumed as a reaction phase, and the amount of the extracted S-compound and the peroxidized catalyst wherein greatly affect the desulfurization rate. Besides, the IL with the dissolved catalyst can be reused many times and regenerated easily.
The adsorptive desulfurization ability of four inorganic Lewis acids (AlCl 3 , FeCl 3 , ZnCl 2 , and CuCl) for three thiophenic S-compounds, viz., 3-methylthiophene (3-MT), benzothiophene (BT), and dibenzothiophene (DBT), from their model oils were studied here experimentally at 290 K. The results were explained in terms of the theory of hard and soft acids and bases (HSAB) reasonably. The results show that AlCl 3 has excellent removal ability for 3-MT with its adsorbance being 141.4 without toluene and 123.0 mgS/g with 25 wt % toluene. It is noteworthy that 3-MT is removed solely through complexing adsorption; in contrast, BT is adsorbed, accompanied with the formation of oil soluble BT oligomers under catalysis of AlCl 3 which can promote the complexation greatly. Further, the addition of benzene and toluene can accelerate the desulfurization rate of 3-MT and BT due to the concentration of aromatics on the adsorbent and the oligomerization between BT and the aromatics.
in Wiley Online Library (wileyonlinelibrary.com).Lewis hard acid AlCl 3 was softened by some butyl halides forming highly polarized liquids. These liquids are similar to the ionic liquids (ILs) with metallic complex anion and varying composition, and thus termed here as carbonium pseudo ILs (CPILs). The CPILs, that is, t-C 4 H 9 Cl-AlCl 3 , n-C 4 H 9 Cl-AlCl 3 , and t-C 4 H 9 Br-AlCl 3 , show very strong desulfurization activity for various thiophenic compounds like 3-methylthiophene, benzothiophene, and dibenzothiophene. The above thiophenic compounds can be removed completely from model oils within 20 min by a very small amount of CPILs reactive extractant. The extractive mechanism is deemed as an acid-base complexation along with alkylation of the thiophenic compounds, and the Lewis acidity comes from both carbonium ion (borderline acid) and the dissolved AlCl 3 (hard acid). The t-C 4 H 9 Cl-AlCl 3 shows good selectivity for three thiophenic compounds even in toluene-containing system. Further, some CPILs show satisfactory desulfurization performance for the model gasoline that mimics the composition of real one.Two alkyl halides, namely t-butyl chloride and n-butyl chloride, were used to soften hard acid AlCl 3 to explore their Figure 1. The three S-compounds in model oil.
A novel integrated process is proposed for the catalytic oxidative desulfurization of fuel oil, in which the oxidant H 2 O 2 is in situ generated by oxidizing 2-propanol with oxygen, and its feasibility is evaluated in terms of the S-conversion of 3-methylthiophene (3-MT), benzothiophene (BT), and dibenzothiophene (DBT) in octane under varying conditions. The catalysis of [π-C 5 H 5 NC 16 H 33 ] 3 [PW 4 O 16 ] is found to be much superior to H 3 PW 12 O 40 and [(C 4 H 9 ) 4 N] 3 [PW 12 O 40 ] due to its good dispersivity in oil and adsorptivity for S-compounds. Some influencing factors for the S-conversion were studied, viz., time, temperature, various S-compounds, and the amount of 2-propanol, initiator, oxygen, and catalyst. All factors that favor the production of the 2-propanol radicals affect the desulfurization rate remarkably. Both BT and DBT can be removed efficiently at mild conditions (1.4 MPa O 2 , 90 °C) in 6 h with S-conversion above 96%, and the resulting sulfones can be separated via settling or filtration.
Excellent desulfurization is achieved via reactive adsorption using Friedel-Crafts acylation materials, that is, acylating reagents and Lewis acids, such as acetyl chloride (AC) and AlCl 3 , being named as acylation desulfurization (ACDS). For model oil, thiophenic compounds, namely, dibenzothiophene, benzothiophene, and thiophene, are removed completely by AC-AlCl 3 within 30 min at room temperature. In this process, thiophenic compounds are acylated by AC under the catalysis of AlCl 3 , and the acylated derivatives are stronger base than original ones due to incorporation of O-containing carbonyl group (C@O) and, thus, adsorbed more easily by AlCl 3 via Lewis acid-base complexation. Further, ACDS mechanism is identified by acylated product characterization and quantum chemistry calculation. Satisfactorily, ACDS is still effective for toluene-rich and real oils, and real oil quality is improved with desulfurization proceeding.Note: (1) k represents rate constant obtained from Supporting Information;(2) desulfurization yield is the data at 30 min reaction time; and (3) Conditions: fivefold AlCl 3 , twofold AC, 303 K.
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