Search

Three carbon materials (CMs) were prepared for the first time by the mechanochemical reaction of calcium carbide (CaC2) and a transition metal chloride (MCln: FeCl3, ZnCl2, or CuCl). Their composition and structure were characterized, and their electrochemical performance was evaluated by cyclic voltammetry, constant current charge and discharge, cycle life, and ac impedance, respectively. The reactions may occur through a series reaction, i.e., metathesis reaction between CaC2 and MCln and self-redox of the resulting metal carbides, forming mesoporous CMs with layered structure and specific area of (160–360 m2·g–1). The CM made from ZnCl2 shows good electrochemical performance and higher specific capacity of 84 F·g–1. Further, CMs with better electrochemical performance may be prepared by using other metal halides. This study validates the effectiveness of mechanochemistry for the activation of CaC2, provides a novel method for CMs synthesis at ambient temperature and mild conditions, and might inspire t...

In this paper, a high-gravity technology was described to prepare two-dimensional molybdenum disulfide nanosheets from bulk materials. This high-gravity field, producing by a rotating packed bed, provides shear force and collision force to exfoliate layered bulk molybdenum disulfide into nanosheets. The effects of rotational speed, surfactant concentration, exfoliation time, packing volume fraction, and exfoliation time on the concentration were systematically studied. The results showed that the concentration of the as-prepared suspension could be easily controlled. The concentration is 0.37 mg/mL under optimum conditions. Moreover, the dispersion of two-dimensional molybdenum disulfide nanosheets could be stabile for a long time. The lateral size of as-produced molybdenum disulfide nanosheets ranged from 50 to 800 nm, and the mean lateral size was 380 nm. Almost 84% of nanosheets were less than five layers. We also demonstrated that high-gravity technology also can be applied to tungsten disulfide. This...

For the deep desulfurization of fuel oil, adsorptive desulfurization (ADS) and oxidative desulfurization (ODS) may be the most viable alternatives to the conventional HDS process. In this work, a highly cross-linked vanadate based polyionic liquid (V-PIL) was synthesized by reacting poly(vinylimidazole) (PVIM) with peroxy-vanadic acid. The as-prepared V-PIL is mesoporous with specific area of 163 m2·g–1 and good adsorptivity for the oxidized sulfur compounds. Further, it can efficiently catalyze the oxidation of dibenzothiophene and benzothiophene with cumene hydroperoxide (CHP), achieving a unified desulfurization processes of ODS and ADS. Its catalytic activity and reusability is superior to the supported vanadate catalysts, e.g. V2O5@active carbon and V2O5@zeolite. The desulfurization capacity of V-PIL is 99% in the first run under specified conditions, i.e. stirring 4 h at 323 K for 500 ppmS DBT oil, with CHP/S being 4 in mole ratio and 3 wt % V-PIL with respect to oil. And over 80% of its desulfuriza...

A hyper cross-linked polymer, HCPVIM, was prepared by copolymerization of vinylimidazole (VIM) and divinylbenzene (DVB), whereby three poly ionic liquids (PILs) were synthesized via quaternization of the imidazole ring by hydrochloric acid, n-butyl chloride and 1,4-bis(chloromethyl) benzene, respectively. Their composition, morphology, specific area and thermal stability were characterized, and their adsorptivity for thiophenic sulfurs was studied. The HCPVIM is a mesoporous sorbent with specific area of 675 m2 g–1, and shows much higher desulfurization ability than its monomer analogue, ethyl imidazole, being about 8.0 mg S g–1 for dibenzothiophene (DBT) at equilibrium S-concentration of 900 ppm. Its desulfurization ability follows the order of DBT > benzothiophene> thiophene, being the same order as alkyl imidazole and imidazolium based ionic liquids. Compared to HCPVIM, the PILs are also mesoporous materials but with negligible micropores, lower specific area of ∼180 m2 g–1, and lowering thermal decomp...

This study was conducted to investigate the effect of inorganic salts on the mass-transfer coefficient of O3 and decolorization of azo dye (Acid Red 14, AR14) solution through ozonation in a microporous tube-in-tube microchannel reactor (MTMCR). The overall volumetric mass-transfer coefficient (KGa) of O3 in the MTMCR was deduced by material balance. The effects of different salts on the KGa of O3 and decolorization efficiency of the AR14 solution were studied, and results show that both were significantly affected by the inorganic salts. Although the KGa of O3 and the decolorization efficiency of AR14 increased with increasing salt concentration and pH, the effect of NaNO3 was much weaker than that of NaCl, Na2SO4, Na2CO3, and NaHCO3. The enhanced KGa of O3 and decolorization could be due to the generation of species with high oxidizing ability in the presence of the salts.

To develop a greener process for reclaiming phenolic compounds from low temperature coal tar, extractive performance of twelve extractants, including mono-, di-, and triethanol amines (MEA, DEA, TEA), six protonated ionic liquids (ILs) thereof with formate (FA) or acetate (Ac) anion, choline chloride, and two polyols (glycol, glycerol), were studied at varying conditions, along with the back extractability of phenols by ether. The extraction performance is MEA > DEA > TEA ≈ ILs > glycol > glycerol, while the back extraction performance of ether is just the opposite. The coexistent toluene in oil and temperature show a little influence on the extraction performance of alcoholic amines and their corresponding ILs. The extraction performance of extractants is consistent with their complexability with phenol, i.e. ethanol amines > ether > ILs > polyols, as manifested by the red shift of the UV spectrum of phenol in the above solvents. [HMEA]FA is the most promising extractant for its overall extraction perfor...

Four metal–organic frameworks (MOFs) are synthesized using two different metal centers and two different organic ligands, viz., Cu3[C6H3(CO2)3]2 (Cu-BTC), Cu[O2C–C6H4–CO2] (Cu-BDC), Cr(OH)[O2C–C6H4–CO2] (Cr-BDC), and Cr3F(H2O)3O[C6H3(CO2)3]2 (Cr-BTC). Their adsorption behaviors for thiophenic sulfurs in model diesel oils are systematically investigated at mild temperatures and follow the order Cu-BTC > Cr-BDC > Cr-BTC ≫ Cu-BDC. Meanwhile, the adsorption capacity of different sulfur compounds follows the order dibenzothiophene (DBT) > benzothiophene (BT) > 3-methylthiophene (3-MT). The MOFs adsorption mechanism is regarded as a combined effect of many factors involving appropriate framework structure, suitable pore size and shape, and exposed Lewis acid site matching the S-compound to be adsorbed. The difference in adsorptive activity among the organosulfurs is mainly ascribed to their π-electron number and the electron density on the S-atom. Finally, the used MOF can be easily regenerated by solvent washi...

Three Keggin-type phosphotungstates, i.e. [C5H5NH]3PW12O40, [C4H6N2H]3PW12O40·3C4H6N2 and [(C4H9)4N]3PW12O40, 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 H2O2 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 H2O2. 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.

A novel integrated process is proposed for the catalytic oxidative desulfurization of fuel oil, in which the oxidant H2O2 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-C5H5NC16H33]3[PW4O16] is found to be much superior to H3PW12O40 and [(C4H9)4N]3[PW12O40] 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 O2, 90 °C) in 6 h with S-conversion above 96%, and the resulting sulfones can be separated via settling or filtration.

The adsorptive desulfurization ability of four inorganic Lewis acids (AlCl3, FeCl3, ZnCl2, 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 AlCl3 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 AlCl3 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.