Abstract: Pyrolysis atmosphere has significant effect on yield and composition of coal tar. A pyrolysis and gasification integrated reactor in laboratory was used to investigate effects of gasification syngas on yield and composition of coal tar. The results show that tar yield of Naomaohu coal reaches the maximum at 600 ℃, and gasification syngas (G-gas) is more beneficial to improve the tar yield at low temperature (550–600 ℃). Especially, 550 ℃ tar yield increases by 4.4% compared with that under N2. With the introduction of G-gas, the yield of tar obtained at high temperature (650–800 ℃) decreases, but the quality of tar obtained at 650–700 ℃ is improved obviously due to the increase of light components. The cracking reaction of aliphatic hydrocarbons and oxygen-containing compounds in volatiles from pyrolysis at 550 and 600 ℃ is intensified by G-gas, thus substituted benzene and naphthalene compounds in coal tar increase. For the volatiles obtained above 650 ℃, the secondary cracking reaction of phenolic compounds is enhanced with the introduction of G-gas, which results in a decrease of phenolic compounds in tar. G-gas is also favorable for the secondary cracking reaction of polycyclic aromatic hydrocarbons in volatiles from pyrolysis at 800 ℃, but more favorable for generation of which in the tar obtained below 700 ℃.
Abstract: Ultrasonic assisted extraction residue (ER) from Naomaohu lignite (NL) was taken as the research object. ER was subjected to methanolysis at 300 ℃, and the effect of KOH was investigated. Composition of the two alcoholysis products, MP (without KOH) and MPKOH (with KOH) was analyzed by chromatograph/mass spectrometer (GC-MS). Benzyl benzoate (BB) and phenyl acetate (PA) were selected as model compounds (MER) for ER, and the alcoholysis products (BBP, BBPKOH, PAP and PAPKOH) were obtained. Results showed that the yield of MPKOH was 93.39%, while that of MP was only 5.25%, indicating that the addition of KOH greatly improved the yield of alcoholysis product. MP consisted of phenols, esters and alkanes with the relative contents of 17.92%, 34.83% and 5.98%, respectively, while the contents of the above three compounds in MPKOH were 34.8%, 10.17% and 8.71% respectively, indicating that transesterification or ester reduction reaction occurred in the alcoholysis process with the addition of KOH accompanied by alkylation reaction. Analysis of alcoholysis products of model compounds showed that methyl benzoate and benzyl alcohol were predominant in BBP, while methyl benzoate disappeared in BBPKOH, and the relative content of benzyl alcohol accounted for 91.85%; phenols were only detected in PAP, and the relative content of phenol was 87.97%. Whereas, the content of methyl substituted anisole and phenol accounted for the largest share in PAPKOH with the contents of 85.64%. Alcoholysis process of the two model compounds showed that, without KOH, transesterification or ester reduction reaction was occurred in the alcoholysis process. And the addition of KOH not only accelerated the above reaction, but also strengthened the alkylation reaction between the subsequent products and methanol.
Abstract: In this paper, three-dimensional hierarchical porous carbons (HPCs) were prepared using coal tar pitch as raw material and α-Fe2O3 as template combined with KOH activation. The as-prepared HPC-3 showed large specific surface area (2003 m2/g), which was due to the synergistic effect of the occupation of α-Fe2O3 (certain mesopores and macropores) and KOH activation (abundant micropores). And the assembled electric double layer capacitor by HPC-3 exhibited the largest specific capacitance (295 F/g) and superior cycling stability (specific capacitance retention of 97.8% after 10000 cycles) in 6 mol/L KOH electrolyte. Meanwhile, the high working voltage (3.6 V) and energy density (60.0 (W·h)/kg) were obtained when it was applied to EMIMBF4 electrolyte.
Abstract: To synthesize simple and efficient catalysts and their application in catalytic conversion of biomass platform compounds to prepare high value-added chemicals has always been the focus of researchers. In this paper, a catalyst composed of iron, manganese, copper and Schiff base ligand derived from amantadine salicylaldehyde was in-situ constructed to catalyze the selective oxidation of 5-hydroxymethylfurfural (HMF) to prepare 5-formyl-2-furancarboxylic acid (FFCA). The ligands and complexes were characterized by nuclear magnetic resonance (NMR), infrared spectroscopy (IR) and single crystal diffraction, and the reaction conditions such as oxidation reaction time, reaction temperature, molar ratio of MnCl2·4H2O to ligand, oxidant and catalyst dosage, etc, were optimized. Under the optimized conditions, 100% conversion of HMF and the FFCA with a yield of 52.1% can be obtained. Finally, on the basis of the reaction results, the HMF oxidation reaction process catalyzed by Mn metal complexes was analyzed.
Abstract: Four typical lignins: alkali lignin, lignosulfonate, hydrolyzed lignin and G-type lignin, were selected to study their gasification weight loss characteristics, kinetic mechanism and product characteristics on a thermogravimetric analyzer (TGA) and fixed bed experiments, in order to reveal the influence of lignin sources on their gasification characteristics. The results showed that the homogeneous model fit the gasification reaction process well. Alkali lignin had the highest pyrolytic activity, reacted at lower temperature, and had the lowest activation energy. However, the structure of pyrolytic coke was dense and the gasification reactivity was poor. G-lignin had similar gasification characteristics with alkali lignin. Lignosulfonate and hydrolyzed lignin had two pyrolysis stages, and their coke gasification reactivities were high. For products characteristics, H2 and CO were the main gas products. Alkali lignin had the H2 yield as high as 55 mmol/g, the highest carbon conversion rate (87%), and the minimum residual coke. However, hydrolyzed lignin and G-lignin had lower gas production, but tar and solid residue were relatively more, which was mainly related to the inorganic mineral content and composition.
Fischer-Tropsch synthesis (FTS) is a promising route to produce various olefins and fine chemicals from non-petroleum carbon sources that can be used to produce synthesis gas, such as coal, natural gas and biomass. Cobalt-based catalysts have gained more attention in FTS for the academic research and industrial applications, owing to their excellent catalytic properties such as low water-gas-shift activity, great Fischer-Tropsch reaction activity and high chain growth probability. The structure of the microscopic active site and the surface adsorption of the cobalt-based catalyst during the Fischer-Tropsch progress have an effect on the product distribution and catalytic performance. In this review, we summarized some advancements in the development of cobalt-based F-T catalysts focusing on the effects of particle size, crystal phase, crystal plane and microscopic active site, with emphasis on the research from the types, surface adsorption behavior and characterization techniques of microscopic active site. Some suggestions for the development of cobalt-based F-T catalysts in the future are also given.
Abstract: Z-scheme photocatalyst holds great promise in photocatalytic H2 evolution. In this work, a ternary Au-OVs-BiOBr-P25 Z-scheme photocatalyst with oxygen vacancies was successfully prepared, in which Au nanoparticles were used as the electron mediators to introduce into BiOBr and P25. The photocatalytic activity of this ternary photocatalyst was evaluated by overall water splitting. The H2 evolution rate of Au-OVs-BiOBr-P25 achieves an amazing value of 384 μmol/(g·h) under UV-vis irradiation. UV-vis DRS and transient photocurrent spectra revealed that the enhanced photocatalytic activity of Au-OVs-BiOBr-P25 was mainly attributed to its widened photo-response range and effective carrier separation. Furthermore, the photocatalytic mechanism was systematically studied by EPR and Photoelectrochemical measurements, which indicated that the overall water splitting occurred through the two-electron pathway. This result will provide us new ideas for developing more efficient photocatalysts for photocatalytic H2 evolution.
Abstract: Solvothermal synthesis technique is an effective method to create composite materials. In this paper, a series of TiO2@MIL-101(Cr) were prepared by the solvothermal method for photocatalytic denitrification of pyridine in fuel under visible light irradiation. The products were characterized by XRD, FT-IR, SEM, TEM, BET, DRS and ESR. The result shows that 20%TiO2@MIL-101(Cr) has high catalytic activity, the pyridine removal efficiency reaches values as high as 70% after irradiation for 240 min. Finally, we obtained the possible mechanism of photocatalytic denitrification according to the HPLC-MS spectrometry results analysis.
Abstract: Direct and selective conversion of methane to methanol under mild conditions still faces grand challenges. In this study, Co3O4/WO3 nanocomposite catalysts were synthesized by facile hydrothermal method, combining with surface impregnation process. The structural composition and micro morphology of Co3O4/WO3 composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and UV-visible absorption spectrum. The catalytic performance of Co3O4/WO3 on the conversion of methane to methanol was investigated under visible light illumination at room temperature. The results show that incorporating Co3O4 can remarkably improve the photocatalytic performance of methane conversion. The optimal catalyst 3.0% Co3O4/WO3 exhibits a methane conversion of 2041 μmol/g after visible light irradiation for 2 h, and the according methanol productivity and selectivity reach 1194 μmol/g and 58.5%, which are 4.03 and 2.39 times of single WO3 respectively. This performance is superior to most reported heterogeneous photocatalysts for methane conversion, meanwhile possessing excellent cyclic stability. Combining the results of transient photocurrent and electron paramagnetic resonance (EPR) with the catalytic activity, the intrinsic mechanism of enhanced methane conversion via introducing Co3O4 is revealed, which is of theoretical significance to design light-driven catalysts for methane conversion to methanol.
Abstract: The Pd-TiO2 electrocatalysts were synthesized via sodium borohydride reduction and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry, chronoamperometry and attenuated total reflectance-Fourier transform infrared (ATR-FTIR). The X-ray diffraction experiments of the Pd-TiO2 showed peaks associated with Pd face-centered cubic (fcc) structure and peaks characteristics of TiO2 (anatase phase) with a tetragonal structure. The TEM images showed that the Pd and TiO2 nanoparticles were well distributed in the carbon support showing some clustered regions with nanoparticle sizes between 7 and 8 nm. Cyclic voltammograms showed an increase in current density values after the glycerol adsorption process. Experiments in alkaline direct glycerol fuel cells at 60 °C showed a higher power density for Pd-TiO2/C (70∶30) in comparison to the commercial Pd/C electrocatalyst indicating that the use of the TiO2 co-catalyst with Pd nanoparticles had a beneficial behavior. This effect can be attributed to the electronic effect or to the bifunctional mechanism. Molecules with high-value added glyceraldehyde, hydroxypyruvate and formate were identified as electrochemical reaction products of glycerol on all prepared electrocatalysts.
Abstract: Electrocatalytic reduction of nitrogen (N2) to ammonia (NH3) by renewable energy-derived electricity provides a new route for sustainable development. But this process requires high-efficiency, high-selectivity and high-stability, inexpensive electrocatalysts. Owing to the unique electronic structure and catalytic mechanism, transition metal nitrides (TMNs) have been widely investigated as electrocatalysts for nitrogen reduction reaction (NRR) in recent years. However, to date, copper nitride-based materials are rarely reported for NRR. In this study, a three-dimensional self-supported copper nitride electrode (Cu3N/CF) was prepared by a simple one-step high-temperature nitridation of copper foam (CF). The structure and morphology of Cu3N/CF were systematically characterized and its NRR catalytic performance and stability were evaluated in neutral media. The results show that Cu3N/CF electrode achieves high ammonia generation rate (1.12 × 10−10 mol/(s·cm2) and faradaic efficiency (1.5%) at −0.2 V vs RHE in 0.1 mol/L Na2SO4. In addition, it also exhibits excellent electrocatalytic cycle stability and structural stability.
Abstract: The Cu-Zn-Al ternary spinel catalysts were synthesized by the wet ball milling method using copper nitrate, zinc nitrate, pseudoboehmite and citric acid as the raw materials. TG-DTA, XRD, N2 physical adsorption, H2-TPR, XPS and other characterization methods were used to study the effects of different Cu/Zn/Al molar ratios on the crystal phase composition, specific surface area, reduction performance and surface properties of the catalysts, and the catalytic performances of the catalysts were investigated by methanol steam reforming (MSR) for hydrogen production. The results indicate that comparing with the binary Cu-Al spinel, Cu-Zn-Al ternary spinel catalysts have high crystallinity, large surface area and are difficult to be reduced, which show improved catalytic performance and totally different sustained release behavior. The Cu-Zn-Al spinel catalyst with Cu∶Zn∶Al = 0.8∶0.2∶2.5 (molar ratio) exhibited the highest stable catalytic activity in MSR under a reaction temperature of 265 ℃, water/methanol ratio of 2 and mass space velocity of 2.25 h−1. The findings of this work might be served as basic data for further research of such ternary spinel catalysts.
Abstract: A series of Nb-modified V2O5-WO3/TiO2 catalysts were prepared by the impregnation method and the effect of Nb loading on their SO2 oxidation activity during the selective catalytic reduction of NOx was investigated. The results indicate that the Nb2O5-V2O5-WO3/TiO2 catalyst with a Nb2O5 loading of 2% exhibits the lowest SO2 conversion of 0.6% for oxidation at 350 °C, whereas the conversion of NOx is still above 95%. The catalysts were characterized by TGA, BET, XRD, H2-TPR, CO2-TPD, XPS and in-situ DRIFTS. The results illustrate that the influence of Nb modification on the crystal structure of V2O5-WO3/TiO2 catalyst is rather insignificant; however, the surface area of the Nb2O5-V2O5-WO3/TiO2 catalyst decreases slightly after the modification with Nb, conducing to a decrease of SO2 adsorption on the catalyst. Meanwhile, the content of oxygen adsorbed on the catalyst surface decreases considerably upon the Nb modification, suggesting a weakened redox performance, which is beneficial to reducing the oxidation of SO2. The in-situ DRIFTS results illustrate that the content of the intermediate VOSO4 product on the catalyst surface decreases over the Nb-modified Nb2O5-V2O5-WO3/TiO2 catalyst, leading to a decrease of SO3 production.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
