A fixed bed reactor and atomic absorption spectroscopy were used to investigate potassium recovery efficiency of Yulin coal loaded with potassium carbonate (ZA-K), Yulin demineralized coal loaded with potassium carbonate (ZA-THK) and synthetic ash (Configurations of four oxides: SiO2, Al2O3, CaO, Fe2O3) loaded with potassium carbonate after reaction. Fourier infrared spectroscopy and Raman spectroscopy were used to study influence of structural evolution of ZA-K and ZA-THK on migration of potassium during pyrolysis. The results show that the yield of water-soluble potassium decreases with increasing temperature. Three times water washing could recover 94.06%−98.80% of the total water-soluble potassium. Formation of insoluble potassium is due to the phase of potassium aluminosilicate formed by potassium, silicon and aluminum in the coal ash. Potassium is easier to volatilize from ZA-THK than that from ZA-K. At 700−850 ℃ potassium in ZA-THK is volatilized 10.28%−44.92% higher than that of ZA-K, resulting from that the ash in ZA-K would fix the loaded potassium in coal ash. Another reason may be caused by decrease in the degree of aromatic polymerization of ZA-THK through demineralization process, leading to more small-ring aromatic structures (2−8 rings) appearing in the coal.

The co-combustion of the low-rank coal with coal derived semi-coke is of great significance to solve the urgent problem of excessively produced semi-coke in China. In this research, the oxy-fuel co-combustion characteristics of Zhundong sub-bituminous coal with bituminous coal derived semi-coke are systematically investigated using thermogravimetric analysis. Compared with air combustion, oxy-fuel atmosphere increased the ignition and burnout temperature by 10 and 40 °C, respectively. Increasing the oxygen concentration to 30% strongly compensated for the slight reduction of the combustion parameters under oxy-fuel condition and much better co-combustion performance was obtained. Three iso-conversional methods, namely, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Starink, were applied to estimate the activation energy, which can be divided into two stages during the co-combustion process. The average activation energy of sub-bituminous coal, the blend and semi-coke were 49.31, 50.82 and 59.00 kg/mol, respectively. Further, the pre-exponential factor and thermodynamic parameters of the enthalpy change, Gibbs free energy change and entropy change were calculated. Interaction indices were innovatively used for both kinetic-thermodynamic parameters and DTG values. An obvious interaction can be observed during the co-combustion process. The kinetic and thermodynamic results demonstrated that the 30% semi-coke ratio was beneficial to co-combustion. Meanwhile, X-ray fluorescence (XRF) and ash fusion analyses proved that the slagging tendency of sub-bituminous coal ash reduced by blending of semi-coke.

The clean and efficient utilization of carbon resources is becoming more and more important, in energy, material, and chemical engineering field, but the mechanism of coke oxidation, especially that of the CO2/CO desorption is not fully studied yet. In this paper, density functional theory was used to study the oxidation mechanism of Zigzag char structure with high coverage of O2, which is related to an oxidation under lower temperature or high pressure. Based on the corresponding quantum chemistry calculation, it is shown that there are several possible pathways for the CO2 desorption process, which may need rearrange to form the structure containing O−C−O clusters. And successively, multiple intermediate reaction steps are required to complete the desorption of CO2. Other than in the literature that the COO–O–C functional group formed first, with then the C–O bond broken and CO2 desorbed respectively, a novel pathway with two C–O bonds broken simultaneously to generate CO2 was found. It results from a functional group of COO–char formed, and certain alternative pathways via C–C bonds breaking were also dealt with, as well as related CO desorptions. The reaction model built was validated by theoretical and experimental results from literature satisfactorily.

A series of non-sulfurized K-Ni-Mo-based catalysts with close contact between Ni and K2MoO4 were prepared by hydrothermal reduction for higher alcohol synthesis from syngas. The as-prepared catalysts were characterized by XRD, N2 adsorption-desorption, H2-TPR, HR-TEM, SEM-EDS, XPS, H2-TPD, CO-TPD and CO2-TPD techniques. The results indicate that the introduction of K facilitates the formation of the K2MoO4 phase while brings about a decrease of NiMoO4. It can significantly assist the non-dissociative activation of CO for insertion and subsequently alcohol formation. Moreover, the addition of K increases the surface basicity, which leads to more amount of basic hydroxy groups on the catalytic surface. The catalytic basicity ameliorates the production of alcohols. In particular, the K0.4-Ni-Mo catalyst shows the best catalytic behavior with CO conversion of 19.6%, total alcohol selectivity of 57.8% and C2+ alcohol selectivity in the total alcohols of 66.5% at GHSV of 5000 h−1, 240 °C, and 5 MPa.

MgO-Al2O3 supports with Mg/Al molar ratio of 0, 0.2, 0.5 and 1.0 were synthesized by coprecipitation method. Mo/M-A0-S, Mo/M-A0.2-S, Mo/M-A0.5-S, and Mo/M-A1.0-S catalysts were respectively prepared by molybdenum loading and followed by prevulcanization processes. Their catalytic performances for hydrogenation of COS in coke oven gas were evaluated in a fixed bed reactor. X-ray photoelectron spectroscopy and Raman spectroscopy were used to characterize the structure and Mo species of catalysts, and the effect of Mg/Al molar ratio on the COS hydrogenation performance of catalyst was investigated. The results show that the changing of Mg/Al molar ratio can modify the physical and chemical structure of MgO-Al2O3 support, the dispersion of Mo and its interaction with catalyst support, and the amount and layer number of MoS2 active sites, so that to improve the activity and selectivity of catalyst. The Mg/Al molar ratio 0.5, which is equal to the stoichiometric ratio of Mg to Al in MgAl2O4, is the most favorite value for MgAl2O4 production. MgAl2O4 can reduce the interaction strength between Mo and catalyst support, enhance Mo dispersion, increase MoS2 amount, and thus promote the catalyst performances. Mo/M-A0.5-S is an excellent catalyst, which can convert 97.7% COS through hydrogenation with H2S selectivity 100% in 550 min at 280 ℃ under the space velocity of 62000 h−1.

Cu-SAPO-44 zeolite catalysts were synthesized by one-step hydrothermal method using cyclohexylamine (CHA) and Cu-amine complex (Cu-TEPA) as co-template. They were used for selective catalytic reduction of nitric oxide with propylene (C3H6-SCR) under lean burning condition. These catalysts were characterized by N2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectroscopy (UV-vis), NH3 temperature-programmed desorption (NH3-TPD) and H2 temperature-programmed reduction (H2-TPR). Compared with pure SAPO-44, the introduction of Cu-TEPA significantly enhanced the catalytic activity of C3H6-SCR. When Cu/Al was 0.25, Cu-SAPO-44 catalyst had the largest specific surface area, abundant acidic sites and moderate isolated Cu2+ species, thus it had the best deNOx performance. With the increase of Cu-TEPA introduction, copper species would aggregate on the surface of the zeolite and form more inactive CuO, thus reducing the denitrification activity. In situ study by DRIFTS indicated that isolated Cu2+ could contribute to the adsorption and activation of NO and C3H6, thus enhancing in the formation of −NCO, which was a key intermediate of the reaction. The Cu-SAPO-44 catalyst maintained more than 60% NOx conversion and more than 90% N2 selectivity in long term test of 50 h, showing appropriate reaction stability.