Catalysts for the desulfurization of gasoline samples were synthesized via the immobilization of well-dispersed phosphotungstic acid (HPW) on Mobil composition of matter-twenty-two (MWW) zeolite. Characterization results indicated that these catalysts possess a mesoporous structure with the retention of the Keggin structure of immobilized HPW. Relevant reaction parameters influencing sulfur removal were systematically investigated, including HPW loading, catalyst dosage, temperature, initial S-concentration, molar ratio of oxidant to sulfide (O/S), volume ratio of MeCN to model oil (Ext./oil), and sulfide species. The 40 wt-% HPW/MWW catalyst exhibited the highest catalytic activity with 99.6% dibenzothiophene sulfur removal from prepared samples. The 40 wt-% HPW/MWW catalyst was recycled four times and could be easily regenerated. Finally, as an exploratory study, straight-run-gasoline and fluid catalytic cracking gasoline were employed to accurately evaluate the desulfurization performance of 40 wt-% HPW/MWW. Our research provides new insights into the development and application of catalysts for desulfurization of gasoline.
Qing Cen,Qiaoyuan Gao,Chenlu Zhang,Yingqi Liu,Qi Wang,Qi Wang
In this study, visible-light-active iron tungstosilicate (FeSiW) was fabricated via solvothermal method . Fe 3+ was applied as counter ion to precipitate with silicotungstic acid (H 4 SiW 12 O 40 ) in methanol solution. It can be observed from FT-IR spectra that the Keggin structure of SiW 12 O 40 4− was well maintained in FeSiW. Besides, the effect of different initial molar ratios of Fe 3+ to H 4 SiW 12 O 40 was investigated (from 4:1 to 4:4). By photoelectrochemical characterizations, such as photocurrent response and Mott-Schottky (M-S) plots, easiest generation of electron-hole pairs and lowest charge transfer resistance can be observed on FeSiW with initial molar ratio of 4:3. Moreover, FeSiW with 4:3 ratio also displayed highest activity for photocatalytic reduction of Cr(VI), despite of the largest band gap (ca. 2.71 eV). The lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of the optimized FeSiW were estimated to be +0.03 V and 2.74 V vs NHE, respectively, which were thermodynamically feasible for Cr(VI) reduction and H 2 O oxidation . Even under acidic condition (pH 3), the optimized photocatalyst displayed good stability in cyclic runs. Therefore, the present study opens a new way for heterogeneous polyoxometalates as efficient photocatalyst for environmental application.
Syngas (H2, CO) is a common industrial feedstock usually produced by coal gasification at high temperatures. Herein, we present an electro-coupled-chemical reforming method that converts renewable biomass carbohydrates into syngas by using lacunary phosphomolybdic acid (MoPA) as the catalyst under mild conditions (pH = 5, <100 °C). The lacunary MoPA derives from the typical Keggin structure but acts as an efficient carbohydrate C–C bond cleavage catalyst due to its active defect sites. It degrades biomass carbohydrates into C1 compounds, such as CO and CO2, with the highest kinetic rate being 22 times higher than the initial Keggin catalyst. The produced CO2 can be self-supplied into the cathode side with coupled CO2 electrocatalytic reduction for syngas yield over the typical AgPd catalyst, and simultaneously, the lacunary MoPA catalyst is regenerated at the anode side with a significant electric energy saving. In the continuous flow running for 3600 s, the current density reaches 50 mA cm–2 at −1.6 V, and the syngas can be obtained with a tunable H2:CO ratio from 2.96 to 1. Compared with conventional syngas production, the electrochemical route provides a full carbon conversion of carbohydrate biomass into syngas with the advantages of a low reaction temperature and near-neutral conditions.
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