Yadong Zhang

Solvothermal synthesis of MoS2 nanospheres in DMF–water mixed solvents and their catalytic activity in hydrocracking of diphenylmethane

MoS2 nanospheres were successfully prepared via a solvothermal process using 1-ethyl-3-methylimidazolium bromide ([EMIM]Br) in a mixed solvent of DMF–water. A probable [EMIM]Br aggregation in different mixed solvents and the formation mechanism of the MoS2 nanospheres are presented. The MoS2 nanospheres delivered high catalytic activity in hydrocracking of diphenylmethane.

Hydroalkylation modification of naphthene-based aromatic-rich fraction and its influences on mesophase development

Naphthene-based aromatic-rich fraction was modified by tetrahydronaphthalene and polyethylene glycol to obtain modified materials which were selected to prepare mesophase pitches by a direct condensation method. The structural composition of modified materials were characterized by simulated distillation (SIMDIS), elemental analysis, Fourier transform infrared spectrometry (FTIR) and 1H nuclear magnetic resonance (1H NMR) spectroscopy. Influences of the naphthenic structures and alkyl chains in modified materials on the formation and development of mesophase structures were investigated by analyzing variations in optical texture, softening point, carbon residue, molecular and microcrystal structure of mesophase pitch. Results showed that the alkyl structures in modified materials treated by tetrahydronaphthalene and polyethylene glycol were mainly naphthenic structures and alkyl chains, respectively. The existence of alkyl structures in modified materials was beneficial for the formation of mesophase with high quality. Moreover, the naphthenic structures had a better improving effect than alkyl chains. Abundant naphthenic structures or an appropriate amount of alkyl chains in feedstock contributed to the preparation of mesophase pitch with large domain structure, low softening point, high carbon residue and ordered microcrystal structure.

Effects of Surface Modification on the Catalytic Performances of Nickel Sulfide Nanocatalysts for Residue Hydrocracking: A Monte Carlo Simulation and Experimental Study

Saturates, aromatics, resin, and C7 asphaltene (SARA) fractions of feedstock were analyzed systematically, and molecular models were constructed. The Monte Carlo method was utilized to investigate the intermolecular interactions between SARA fractions and the ligands absorbed on nickel sulfide nanocatalysts. Additionally, the structural characteristics of the hydrocracked products were analyzed by using elemental analysis, 1Hu2005NMR spectroscopy, and FTIR spectroscopy to study the effect of surface modification on the catalytic performances of nickel sulfide nanocatalysts. Simulation results reveal that oleic acid and 1‐dodecanethiol have a better miscibility with aromatic fractions of residue than cetyltrimethyl ammonium bromide and that oleic acid has a high affinity and selectivity to C7 asphaltene. Adsorption experiments show that nickel sulfide nanocatalysts modified with oleic acid and 1‐dodecanethiol present a certain “core affinity” in the diffusion of residue colloid, which leads to a higher catalyst concentration in C7 asphaltene than the average value in the feedstock. Subsequently, experimental data demonstrate that surface modification with oleic acid and 1‐dodecanethiol enhances the catalytic activity of nickel sulfide nanocatalysts, which also facilitates the hydrogenation of C7 asphaltene. Furthermore, nickel sulfide nanocatalysts modified with oleic acid show the best hydrogenation and anticoke activity because of the affinity between oleic acid and C7 asphaltene.

Preparation and characterization of petroleum-based mesophase pitch by thermal condensation with in-process hydrogenation

A petroleum aromatic-rich component was used to prepare mesophase pitch by thermal condensation. In-process hydrogenation method was employed to achieve the hydrogenation reaction of intermediates generated during the thermal reaction using tetrahydronaphthalene (THN) as a hydrogen donor. Impacts of in-process hydrogenation on the properties of intermediates and mesophase pitches were investigated. It was found that the in-process hydrogenation was conducive to the generation of hydrogenated intermediates with concentrated extracted component distribution, uniform molecular structure and abundant naphthenic structures. The characterizations of mesophase pitches showed that the in-process hydrogenation contributed to the preparation of mesophase pitch with concentrated extracted component distribution, low softening point, large domain structure and ordered crystal structure. This was due to the increasing contents of naphthenic structures in intermediates. Moreover, the increase of methylene bridges in the product was the critical reason for improving the products properties.

Influence of boiling point range of feedstock on properties of derived mesophase pitch

The composition of raw material was optimized by vacuum distillation. The carbonization behavior of two kinds of raw material was followed by polarizing microscope, softening point, carbon yield and solubility. Two kinds of mesophase pitch have been monitored by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), elemental analysis and 1H nuclear magnetic resonance (1H-NMR). The analysis results suggested that raw material B (15wt% of A was distillated out and the residue named B) could form large domain mesophase pitch earlier. The shortened heat treat time favored the retaining of alkyl group in mesophase pitch and reduced the softening point of masophase pitch.

Improvements to quality of needle coke by controlled carbonized conditions

In this study, the selected aromatic-rich fraction derived from hydrocracking tail oil was carbonized and further improvement in the quality of resultant coke was achieved by promoting temperature at the solidification stage. In comparison with conventional process carried out isothermally and isobarically, the coupling analysis between formation and subsequent uni-axial orientation of mesophase textures during the controlled process was systematically discussed on the basis of the mutual relevance among mesophase texture evolution, gas evolution rate and solidification rate of intermediates. The results show that on the premise that formation of bulk mesophase, appropriate rate of gas evolution at a right time of solidification contributes to fine produces fine fibrous mesophase aligned uni-axially and less pores. Moreover, the intermediates with solidification index of 2∼6 are suitable for deformation induced by gas evolution.In this study, the selected aromatic-rich fraction derived from hydrocracking tail oil was carbonized and further improvement in the quality of resultant coke was achieved by promoting temperature at the solidification stage. In comparison with conventional process carried out isothermally and isobarically, the coupling analysis between formation and subsequent uni-axial orientation of mesophase textures during the controlled process was systematically discussed on the basis of the mutual relevance among mesophase texture evolution, gas evolution rate and solidification rate of intermediates. The results show that on the premise that formation of bulk mesophase, appropriate rate of gas evolution at a right time of solidification contributes to fine produces fine fibrous mesophase aligned uni-axially and less pores. Moreover, the intermediates with solidification index of 2∼6 are suitable for deformation induced by gas evolution.

Influence of carboxyl anion on the dissolution of chitosan in cholinium-based ionic liquids

Chitosan can be applied in because of its excellent antimicrobial activity and abundant bio renewable and biodegradable resource. To better utilize this kind of native polysaccharide, it is still necessary to develop an efficient chitosan solvent system. Tn present study, 6 kinds of novel choline carboxylate ionic liquids (ILs) were developed. The solubility of chitosan in these H2O-ILs with different molar ratio were measured at 25 °C. The effect of the carboxylate anion of the ILs on chitosan solubility was estimated and found that the solubility of chitosan in the H2O-IL increased with the increasing of alkyl chain length in the anion. Moreover, the H2O-IL solution would not able to dissolve chitosan because the proton H was alternated by employing NH2 or OH group. The H2O-[Ch][CH3CH2CH2COO] (Rmol=6:1) solvent system exhibits highly efficient capacity for the dissolution of chitosan, and the solubility of chitosan reached up to 20.8 wt.%. From NMR measurement, these results could be explained by the possible interaction between carboxylate anion and chitosan and the strong hydration of the carboxyl group in the IL, suggesting that anionic structure have a significant impact on the dissolution of chitosan in the H2O-IL solvent system. Altogether, these results would provide an important evaluation indicator for screening the most suitable solvent system of chitosan.Chitosan can be applied in because of its excellent antimicrobial activity and abundant bio renewable and biodegradable resource. To better utilize this kind of native polysaccharide, it is still necessary to develop an efficient chitosan solvent system. Tn present study, 6 kinds of novel choline carboxylate ionic liquids (ILs) were developed. The solubility of chitosan in these H2O-ILs with different molar ratio were measured at 25 °C. The effect of the carboxylate anion of the ILs on chitosan solubility was estimated and found that the solubility of chitosan in the H2O-IL increased with the increasing of alkyl chain length in the anion. Moreover, the H2O-IL solution would not able to dissolve chitosan because the proton H was alternated by employing NH2 or OH group. The H2O-[Ch][CH3CH2CH2COO] (Rmol=6:1) solvent system exhibits highly efficient capacity for the dissolution of chitosan, and the solubility of chitosan reached up to 20.8 wt.%. From NMR measurement, these results could be explained by the po...

Aluminum and iron leaching from power plant coal fly ash for preparation of polymeric aluminum ferric chloride

ABSTRACT In this work, aluminum and iron existing in coal fly ash were extracted by the method of hydrochloric acid leaching. Effects of solid–liquid ratio, reaction temperature, reaction time, acid concentration, and raw ash mesh on recovery efficiencies of Al2O3 and Fe2O3 were investigated. X-ray diffraction analysis indicated that anhydrite, hematite, mullite and quartz were the dominant minerals in the raw fly ash sample. X-ray fluorescence technique was applied to determine the mass fractions of chemical components in the raw ash and leached residues, while the concentrations of Al2O3 and Fe2O3 in leaching solutions were measured by titration method. The optimal recovery efficiencies of Al2O3 and Fe2O3, obtained under the reaction condition of 95°C, 5u2005h, acid concentration of 20u2005wt.%, a solid–liquid ratio of 1:3.5 and raw ash mesh of 400, were 42.75% and 35.10%, respectively. After removing the leached residues, the leaching solutions were employed to manufacture flocculants of polymeric aluminum ferric chloride for treating the oil recovery wastewater from polymer flooding, which possessed high contents of suspended solids (SS) and oils. Microfiltration membrane and ultraviolet spectrophotometer were utilized to determine the contents of SS and oils in water samples. Through adjusting Al/Fe molar ratio to 20:1 and basicity to 70%, the maximum removing efficiencies of SS and oils can be achieved, respectively 96.1% and 91.5%. Moreover, increasing the iron content and basicity of flocculants within certain ranges contributed to improving the settling characteristic of flocs.