Abstract: The distribution of sulfur and heavy metals in char of Gansu lignite and Shanxi subbituminous coal was studied by means of pyrolysis and magnetic separation at different pyrolysis temperatures. The contents of sulfur and heavy metal elements in char were analyzed and determined by ICP-OES and ICP-MS, and the mineral composition and apparent morphology of char were characterized by XRD and SEM-EDS. The results show that the highest desulfurization rates of Gansu lignite and Shanxi Subbituminous coal can reach 52.37% and 17.54% respectively under optimal conditions. This is related to the phase transition behavior of pyrite during pyrolysis. The desulphurization rate of Shanxi subbituminous char is lower than that of Gansu lignite char mainly because the occurrence and inclusion of associated minerals and the organic matter influence the transformation of pyrite during pyrolysis. Ni and Cr have a strong affinity with Fe–S minerals, which are enriched into magnetic char with sulfur. At 800 ℃, Cr content in magnetic char of Gansu coal and Shanxi coal is 8698.25 µg/g and 32327.47 µg/g higher than that in non-magnetic char, respectively. The pyrolytic magnetization of low-rank coal and the distribution of sulfur and heavy metals in its char products provide data support and a new idea for removal of sulfur and heavy metals from coal.
Abstract: The co-gasification of furfural residue with coal is a feasible way to realize its clean and efficient utilization, but there is a high content of alkaline components in the furfural residue ash. Therefore, the effect of furfural residue addition on the fusion temperature of gasification coal ash was investigated, in which a typical furfural residue and two gasification coals with different ratios of silicon to aluminum (Si/Al) were selected. X-ray diffraction instrument (XRD) was used to measure the mineral evolution of co-gasification ash at different temperatures. The phase change in equilibrium state was calculated by the software FactSage. The results show that with the increase in furfural residue addition ratio, the fusion temperatures of both gasification coal ashes first increase and then decrease, while the increase trend of fusion temperatures for the coal with a high Si/Al ratio is more significant. When the furfural residue is added, the resulting high melting point mineral of gasification slag is changed from anorthite (CaAl2Si2O8) to leucite (KAlSi2O6) that is still present as a solid phase at 1300 ℃, resulting in an increase of AFTs. The coal ash with more amount of SiO2 can react with K2O to produce more leucite (KAlSi2O6) with a higher fusion point, thus causing the ash fusion temperatures to rise. However, as the ratio of furfural residue addition continues to increase, the ash fusion temperatures decrease, which is attributed to the formation of kaliophilite (KAlSiO4) with a low fusion point that is generated in the presence of higher content of K2O.
Abstract: The morphology of nickel and vanadium compounds in the asphaltenes were investigated via hydropyrolysis with the help of inductively coupled plasma mass spectrometer (ICP-MS), ultraviolet-visible (UV-Vis), high-temperature gas chromatography atomic emission detection (HT GC-AED), and positive-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (+ESI FT-ICR MS). The results showed that the toluene soluble yields of products decreased from 64% to 19% as the hydropyrolysis temperature increased from 330 to 410 ℃, while the abundance of nickel and vanadium compounds detected by GC-AED increased significantly. The molecular composition distribution of nickel and vanadyl porphyrins showed rhythmic changes with different temperatures in the hydropyrolysis of asphaltenes.
Abstract: For the oil samples before and after fixed bed hydrogenation reaction at different space speeds, transformation behavior of iron and calcium compounds were studied. The oil samples were decomposed with acid and then extracted with aqueous alcoholic solution of sodium hydroxide. The corresponding petroleum acids derived from petroleum acid salts were obtained. The structure of petroleum acid was characterized by infrared spectrometry, element analysis, hydrogen nuclear magnetic spectrum, nuclear magnetic carbon and high resolution mass spectrometry. In order to study the transformation of petroleum acid in thermal reaction, the obtained petroleum acid was characterized by thermogravimetric mass spectrometry. The transformation process of petroleum acid in thermal reaction was analyzed, and then the transformation process of iron and calcium compounds in thermal reaction was obtained. The results show that the main components of oil acid in residue before and after the hydrogenation reaction are naphthenic acid existing as the form of polymer. Before and after the thermal modification process, petroleum acid is decomposed obviously, and the main products are CO2, C3H8 and other substances. With the increase of reaction depth, the degree of decarboxylation and chain breaking reaction of petroleum acid increases, which further makes petroleum acid decomposition.
Abstract: The effects of supports (CeO2, ZrO2, MnO2, SiO2 and active carbon) on the structure and catalytic performance of Ru-based catalysts for Fischer-Tropsch synthesis to olefins (FTO) were investigated. It was found that the intrinsic characteristics of supports and the metal-support interaction (MSI) would greatly influence the catalytic performance. The catalytic activity followed the order: Ru/SiO2 > Ru/ZrO2 > Ru/MnO2 > Ru/AC > Ru/CeO2. As far as olefins selectivity was concerned, both Ru/SiO2 and Ru/MnO2 possessed high selectivity to olefins (>70%), while olefins selectivity for Ru/ZrO2 was the lowest (29.9%). Ru/SiO2 exhibited the appropriate Ru nanoparticles size ( ~ 5 nm) with highest activity due to the relatively low MSI between Ru and SiO2. Both Ru/AC and Ru/MnO2 presented low CO conversion with Ru nanoparticles size of 1−3 nm. Stronger olefins secondary hydrogenation capacity led to the significantly decreased olefins selectivity for Ru/AC and Ru/ZrO2. In addition, partial Ru species might be encapsulated by reducible CeO2 layer for Ru/CeO2 due to strong MSI effects, leading to the lowest activity.
Abstract: In this paper, three metal oxides, ZrO2, Al2O3 and MnO2, loaded with 1% content on hexagonal nanosheets of Co3O4 (NMS-Co), respectively, were prepared as reversed-phase catalyst models to investigate the effects of metal oxides on the performance of cobalt-based catalysts for Fischer-Tropsch synthesis. The results of H2-TPD, CO-TPD and catalyst performance evaluation revealed that ZrO2 and Al2O3 could significantly increase the active sites of NMS-Co catalysts, lower the reaction temperature from 230 ℃ to 170 and 180 ℃, respectively, and increase the heavy hydrocarbon generation rate by 2.5 and 2 times, respectively, under the same conversion conditions. The CH4 selectivity was reduced from 37.8% to 3.6% and 12.0%, respectively. However, MnO2 increased the CO conversion only from 30.9% to 45.5% and decreased the CH4 selectivity to 16.5%. A new idea is proposed to investigate the effect of metal oxides on the performance of cobalt-based Fischer-Tropsch catalysts.
Abstract: The ZnO-ZrO2 catalyst was prepared by the deposition-precipitation method using ZrO2 as the carrier obtained from calcining commercial zirconium hydroxide (Zr(OH)4). And the catalytic performance was evaluated at 873 K in CO2-assisted ethane oxidative dehydrogenation reaction (CO2-ODHE). The physical-chemical properties and morphology were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectra, High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectra (XPS), CO2 temperature-programmed desorption (CO2-TPD). The results show that ZnO were doped into the surface lattice of ZrO2 on the 5%ZnO-ZrO2 catalyst, generating highly dispersed ZnO species and oxygen-deficient regions on catalyst surface. 5%ZnO-ZrO2 catalyst could selectively breaking C−H bond instead of C−C bond, delivering excellent catalytic performance. 210 μmol/(gcat·min) of C2H4 formation rate could compare favorably with the data reported on noble metal and transition metal carbides. Additionally, the possible mechanism is discussed.
Abstract: In this study, the PtZn/β-x catalysts (x refers to SiO2/Al2O3 mole ratio) were synthesized by co-impregnation method and the effect of Si/Al ratio of the β zeolite on propane non-hydrogen dehydrogenation was explored. A series of characterization such as XRD, BET, HAADF-STEM, NH3-TPD, C3H6-TPD were applied to investigate the phase structure, surface properties of catalysts, and their effects on the reaction performances. The results showed that, with the increase of Si/Al ratio, the catalytic stability would be enhanced following the order of PtZn/DeAl-β > PtZn/β-40 > PtZn/β-30 > PtZn/β-25, while the number of strong acid sites of the catalyst (PtZn/β-30 > PtZn/β-40 > PtZn/β-25 > PtZn/DeAl-β) was affected by the Si/Al ratio to some extent, which was opposite to the order of the propylene selectivity. Therefore, the control of the Si/Al ratio of zeolite is very important for optimizing the properties of the catalysts for propane dehydrogenation reaction. The catalysts with few strong acid sites, weak adsorption of propylene and large specific surface area are contributed to higher propane conversion, propylene selectivity and catalytic stability.
Abstract: The catalysts were prepared by loading about 0.5% Pt noble metal on Y molecular sieves, ZSM-5 molecular sieves and β molecular sieves with similar Si/Al ratios. The crystal structures of the molecular sieves with different topologies, elemental compositions, pore structures, activities, and Al distributions were investigated by means of XRD, XRF, TEM, N2 physical adsorption and desorption, NH3-TPD, Py-FTIR, and 27Al NMR. And then the effect of topology on the catalytic performance of n-dodecane isomerization reaction was investigated. The results showed that when the Si/Al ratios were close to each other, the ZSM-5 molecular sieve had the highest total acid and skeleton Al ratio and the smallest average pore size, the Y molecular sieve had the lowest total acid and skeleton Al ratio and the largest average pore size, and the β molecular sieve's total acid, skeleton Al ratio, and average pore size were between the two others, which indicated that different topologies of the molecular sieves with different combinations of Si/Al atoms affected not only the structure of the pores and the size of the pore but also the number of acidity. In the n-dodecane isomerization reaction, the Pt/ZSM-5 catalyst had the highest activity and the main reaction occurred on the outer surface without selectivity, the Pt/Y catalyst had the lowest activity and the isomerization reaction mainly occurred inside the pores, while the Pt/β catalyst had the activity between the other two catalysts and the isomerization reaction occurred dominantly at the pore opening as the key-locking reaction.
Abstract: This article investigates the promoting effect of gallium (Ga) on the activity of Ga-WOx/SBA-15 catalyst for cis-cyclooctene epoxidation with H2O2. The optimal catalyst of 0.3Ga-WOx/SBA-15 offered a turnover frequency (TOF) of 112 h–1, which was nearly two times than that of WOx/SBA-15 (57 h–1). The low apparent reaction activation energy for 0.3Ga-WOx/SBA-15 (49.6 kJ/mol vs 64.0 kJ/mol for WOx/SBA-15) was also in line with its superior performance. Kinetic analysis demonstrated stronger adsorption of H2O2 on 0.3Ga-WOx/SBA-15 surface, facilitating the H2O2 activation. Based on the characterizations and catalytic performance, the improvement of Ga was attributed to the increase of Lewis acid sites and the enhancement of electrophilicity. Furthermore, the metal hydrogen peroxide (M-OOH) was identified as the primary intermediate.
Abstract: Developing highly active and low cost hydrogen evolution electrocatalysts is an imminent task to improve the efficiency of water electrolysis hydrogen production, achieve large-scale hydrogen production, and promote the development and utilization of hydrogen energy. Molybdenum disulfide (MoS2) has shown a certain potential in the field of hydrogen evolution catalysis, and its modification to improve the catalytic activity and replace the platinum-based catalyst has become a research hotspot in recent years. A simple one-step solvothermal method was used to successfully synthesize a Ni-doped electrocatalytic hydrogen evolution (HER) catalyst Ni@MoS2, which had excellent electrocatalytic hydrogen evolution activity and good stability. The 20Ni@MoS2 as prepared at 240 ℃ exhibited better HER performance with a low overpotential of 190 mV at 10 mA/cm2 and Tafel slope of 162 mV/dec in acidic medium.
Abstract: In this paper, Fe-doped nickel selenide and nickel sulfide composites was in-situ grown on nickel foam (NF) to prepare Fe-NiSe@NiS/NF by solvothermal method. Benefit from the optimized electron structure by Fe doping, the synergistic effect of NiSe@NiS and faster electron transfer, Fe-NiSe@NiS/NF exhibited excellent OER activity with the overpotential of 330 mV at 150 mA/cm2 in 1 mol/L KOH solution. The voltage barely changed after 40 h of test.
Abstract: In this paper, reduced graphene oxides wrapped hollow Fe2O3 spheres (Fe2O3@rGO) were successfully prepared by solvothermal method. Results show that plenty of Fe−O−C bonds between reduced graphene oxides and Fe2O3 significantly improved electron transfer rate of the composite anodes, and confinement effect of reduced graphene oxides slowed the pulverization rate of Fe2O3 during charge/discharge process. As expected, wrapped structured Fe2O3@rGO anode exhibited high rate capability of 514 mA·h/g at high current of 5.0 A/g and durable cycling life over 500 cycles with a capacity of 987 mA·h/g under 0.5 A/g with a capacity retention of 81.1%. This work provides an effective strategy for the preparation of high-rate and long-life graphene composite anode materials.
Abstract: Mo-doped Zn0.5Cd0.5S was prepared and compounded with Ti3C2 nanosheets by hydrothermal method. The crystal structure, surface composition, microscopic morphology, and photoelectric properties of the photocatalysts were analyzed by XRD, SEM, TEM, XPS, UV-vis DRS, fluorescence spectroscopy, transient photocurrent methods. The results showed that the doping of Mo caused changes in the lattice structure of Zn0.5Cd0.5S, while the loading of Ti3C2 increased the photocatalytic active site and accelerated the electron transfer rate. The photocatalytic activity was investigated by degrading the tetracycline solution under visible light irradiation with simultaneous H2 production. The results showed that with the synergistic effect of Mo doping and loaded Ti3C2, the degradation rate of tetracycline (TC) reached more than 70% within 60 min, while the H2 yield reached 883 μmol/(g·h). The radical capture experiments proved that the main active substance for degradation was holes and for H2 production was electrons.
Abstract: As a global pollutant, mercury emission is increasingly restricted in recent years. It is urgent to explore a new and efficient mercury removal technology for coal-fired power plants. A new acid-assisted electrochemical oxidation (AEO) technique for mercury removal was proposed using platinum plate as cathode and fluorine-doped tin dioxide (FTO) glass as anode. The effects of acid type, acid concentration, applied direct current (DC) voltage, electrolyte type, SO2, NO and O2 on the Hg0 removal efficiency were carried out. The results indicated that the mercury removal efficiency increased with the increase of DC voltage and nitric acid concentration. When the concentration of nitric acid increased to 0.15 mol/L, the mercury removal efficiency remained unchanged. SO2 and NO inhibited the removal of Hg0 in AEO system, but the inhibition was reversible. Compared with the mercury removal efficiency under single experimental conditions, the mercury removal efficiency of electrochemical oxidation can reach 96% under the experimental conditions of 0.1 mol/L nitric acid and 4V DC voltage, suggesting that the synergistic effect of nitric acid and DC voltage plays a key role. According to the experimental results, the mechanism of Hg0 removal in AEO system was analyzed. At the anode, Hg0 was oxidized by hydroxyl radical (•OH) generated by the oxidation reaction on the anode surface. At the cathode, dissolved oxygen or O2 adsorbed on the surface of Pt is reduced to form anionic superoxide radicals (•${\rm{O}}_2^- $). Moreover, parts of •${\rm{O}}_2^- $ would produce •OH with the aid of electron at acidic condition. Free radicals capture experiments showed that •O$_2^- $ and •OH were the main active substances for the removal of Hg0 by acid-assisted electrochemical method. The research is helpful for the development of effective electrochemical techniques for industrial mercury removal and recycling of industrial acid waste.
Abstract: Carbon dioxide is one of the most main greenhouse gases causing the global warming, however, as a rich C1 resource, the high value utilization of CO2 has attracted wide attention. Cyclic carbonate is an excellent medium for batteries and capacitors, which is widely used in industrial production. Therefore, it is of great significance to convert CO2 into cyclic carbonate from the viewpoint of environmental protection and resource utilization. In this paper, we synthesized a series of imidazole heterogeneous catalysts supported on polystyrene resin, and the catalytic activity for cycloaddition reaction of CO2 in high pressure reactor was studied. The results showed that PS-TBIM-PCIMBr2 exhibited the excellent and stable catalytic activity. PS-TBIM-PCIMBr2 was also used to prepare propylene carbonate in the continuous fixed-bed reactor and the yield of PC was still 91% after 500 h.
Abstract: The chemical conversion of CO2 is considered as one of the effective measures to reduce carbon emission, where breakthroughs have been made in the thermo-catalytic hydrogenation of CO2 to ethanol in recent years. However, the synthesis of ethanol from CO2 still suffers from some problems such as low ethanol yield and abundant by-products. In this paper, the research progress made in the thermo-catalytic hydrogenation of CO2 to ethanol was reviewed. The performance of various catalysts with zeolites, metal oxides, perovskites, silica, organic frameworks and carbon-based materials as the support was evaluated and the synergistic effect of different metals on the CO2 conversion and the intervention of various active species on the reaction were analyzed. Accordingly, the catalyst systems that can effectively promote the adsorption and activation of CO2 and the coupling of C–C bond were summarized. Finally, the appropriate conditions as well as possible reaction mechanism for the CO2 hydrogenation to ethanol were proposed. The insight shown in this paper should be beneficial to designing efficient catalysts, optimizing the reaction conditions and understanding the mechanism of CO2 hydrogenation to ethanol in the future.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
