燃料化学学报最新文献

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 °C, Cr content in magnetic char of Gansu coal and Shanxi coal is 8698.25 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.

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 (^.O⁻₂). Moreover, parts of ^.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.

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/(g_cat·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.

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 °C, 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.

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 °C, 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.

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.

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.

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.

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.

This article investigates the promoting effect of gallium (Ga) on the activity of Ga-WO_x/SBA-15 catalyst for cis-cyclooctene epoxidation with H₂O₂. The optimal catalyst of 0.3Ga-WO_x/SBA-15 offered a turnover frequency (TOF) of 112 h^–1, which was nearly two times than that of WO_x/SBA-15 (57 h^–1). The low apparent reaction activation energy for 0.3Ga-WO_x/SBA-15 (49.6 kJ/mol vs 64.0 kJ/mol for WO_x/SBA-15) was also in line with its superior performance. Kinetic analysis demonstrated stronger adsorption of H₂O₂ on 0.3Ga-WO_x/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.