Institute of Coal Chemistry, Chinese Academy of Sciences

Li X., Chen Y., Zhu S., Jia X., Wang J., Fan G., Dong M., Fan W.

AbstractA series of potassium titanate nanowires (KTO) with different K content were prepared by hydrothermal treatment, followed by anchoring Au nanoparticles (NPs) using the deposition‐precipitation method. The obtained Au/KTO‐24 showed a furfural (FF) conversion of 100% and a furoic acid (FA) yield of 96% at 80 °C and 1 MPa O2 for 2 h in FF oxidation system. K improves metallic Au NPs dispersion and induces a negative shift of Au0 4f binding energy. Kinetic studies show that Au/KTO‐24 displays low apparent activation energy (51.23 kJ/mol). The catalytic mechanism of FF oxidation to FA was investigated with in situ FT‐IR (Fourier transform infrared) spectroscopy and DFT (density functional theory)  calculations, which indicates that the high performance of Au/KTO‐24 is attributed to not only its abundant numbers of surface Au active sites but also its interfacial Au─O─K structure that facilitates the activations of FF and O2.

Zhang C., Lv H., Wang K., Sun P., Liu S., Chu X., Yuan M., Li N., Zhao S.

Gohy J., Yan S., Liu J., He Z., Jia H., Chen Z., Zhang Y.

AbstractThe swelling of a polymer matrix by ionic liquids and additional lithium salts may lead to the formation of ionogel electrolytes. However, the introduction of additional ions usually results in a decreased lithium‐ion transference number, because of the trapping of the lithium ions in clusters and polymer‐ion complexes. Achieving highly efficient lithium‐ion migration and increasing lithium‐ion transference number (tLi+) are however crucial for the successful application of ionogel electrolytes. Herein, we design a crosslinked polyrotaxane network and then introduce ionic liquid and a lithium salt to obtain an ionogel electrolyte based on the principle of competitive coordination with the lowest binding energy for lithium ions coordinated with both the polymer network and ionic liquid clusters. This facilitates their migration within the ionogel and their release from the coordination environment, thereby improving lithium‐ion transport efficiency (ionic conductivity of 2.2×10−3 S cm−1 and tLi+=0.45 at 20 °C). As proof of concept, the lithium‐lithium symmetrical cells achieve stable cycling for 2000 hours, while the NMC622||Li battery demonstrates good rate performance and excellent cycling stability at 20 °C (theoretical initial capacity, 300 cycles with a single cycle capacity loss of 0.03 %). This work provides new insights for the design and synthesis of ionogel electrolytes, facilitating lithium ion migration within the electrolytes.

Zhang M., Qin G., Li P., Zhang X., Chang H., Zhou Z., Zhao W., Huang X., Tang K., Ning Y., Song C., He P.

Epoxidation of long-chain α-olefins (LAOs) is a process of paramount importance, particularly in the preparation of epoxides. Traditional epoxidation methods, such as the chlorohydrin method and peracid method, suffer from issues such as poor selectivity, by-product formation, and environmental pollution. Mukaiyama epoxidation, with its mild reaction conditions and exceptional selectivity, has attracted widespread attention and considerable research. Transition metal oxide catalysts show potential in the reaction; however, the catalytic efficiency still require substantial improvement due to dilemma of substance activation. In this study, a synergistic enhancement method was employed, achieved through the creation of oxygen vacancies and the electron-rich nature of Cu. The substitution of Cu with Sn in CuO facilitates the creation of oxygen vacancy (Vo), thereby enhancing absorption and activation of O2. The conversion for O2 activation paves the way for the formation of benzoyl peroxy radicals. Moreover, the interaction between Sn and Cu promotes charge transfer from Sn to Cu, resulting in an electron-rich Cu surface that significantly accelerates the dehydrogenation of benzaldehyde. The synergistic enhancement protocol exhibits near-quantitative performance, delivering an oxide yield of 92.9%. This study introduces an innovative dual-promotion catalytic strategy for Mukaiyama epoxidation utilizing readily available O2, providing profound insights into the optimization design of transition metal oxide catalysts and beyond.

Gao B., Cao G., Feng Y., Jiao Y., Li C., Zhao J., Fang Y.

The removal of tar and CO2 represents a critical challenge in the production of biomass gasification syngas, necessitating the development of advanced catalytic systems. In this study, plasma-enhanced catalytic CO2 reforming was employed to remove biomass tar, with toluene selected as a model compound for biomass tar. Supported Nix-Fey/Al2O3 catalysts, with varying Ni/Fe molar ratios (3:1, 2:1, 1:1, 1:2, and 1:3), were synthesized for the CO2 reforming of toluene in dielectric barrier discharge (DBD) non-thermal plasma reactors. The experiments were conducted at 250 °C and ambient pressure. The effects of various Ni/Fe molar ratios, discharge powers, and CO2 concentrations on DBD plasma-catalytic CO2 reforming of toluene to synthesis gas were analyzed. The results indicate that CO and H2 are the primary gaseous products of toluene decomposition, with the selectivity for these gaseous products increasing with the discharge power. Increasing discharge power leads to a higher selectivity for CO and H2 production. A CO2/C7H8 ratio of 1.5 was found to effectively enhance the catalytic performance of the system, leading to the highest toluene conversion and syngas selectivity. The selectivity of the Nix-Fey/Al2O3 catalysts for H2 and CO follows the following order: Ni3-Fe1/Al2O3 > Ni2-Fe1/Al2O3 > Ni1-Fe1/Al2O3 > Ni1-Fe2/Al2O3 > Ni1-Fe3/Al2O3. Notably, the Ni3-Fe1/Al2O3 catalyst exhibits a high CO2 adsorption capacity due to its strong basicity, demonstrating significant potential for both tar conversion and carbon resistance.

Wang Y., Cao X., Dai Y., Yan T., Zhang X., He H., Xie Y., Lin T., Song C., He P.

This study investigates the hydroformylation of C5+ olefins derived from Fischer–Tropsch synthesis (FTS) using Rh-based catalysts supported on zeolites (MFI, MEL) and SiO2. A series of catalysts were synthesized through two different methods: a one-pot hydrothermal crystallization process, which results in highly dispersed Rh species encapsulated within the zeolite framework (Rh@MFI, Rh@MEL), and an impregnation method that produces larger Rh nanoparticles exposed on the support surface (Rh/MFI, Rh/MEL, Rh/SiO2). Characterization techniques such as BET, TEM, and FTIR were employed to evaluate different catalysts, revealing significant differences in the dispersion and accessibility of Rh species. Owing to its more accessible mesoporous structure, Rh/SiO2 with a pore size of 5.6 nm exhibited the highest olefin conversion rate (>90%) and 40% selectivity to C6+ aldehydes. In contrast, zeolite-encapsulated catalysts exhibited higher selectivity for C6+ aldehydes (~50%) due to better confinement and linear aldehyde formation. This study also examined the influence of FTS byproducts, including paraffins and short-chain olefins, on the hydroformylation reaction. Results showed that long-chain paraffins had a negligible effect on olefin conversion, while the presence of short-chain olefins, such as propene, reduced both olefin conversion and aldehyde selectivity due to competitive adsorption. This work highlights the critical role of catalyst design, olefin diffusion, and feedstock composition in optimizing hydroformylation performance, offering insights for improving the efficiency of syngas-to-olefins and aldehydes processes.

Liang C., Zhang D., Li X., Liu Y., Chen C., Wang Q., Hou B., Ma Z., Wang K.

Hydrogen spillover, as a common phenomenon, pervasively occurs in heterogeneous catalysis. Nevertheless, the understanding of the dynamic mechanism of hydrogen spillover in the typical Pt/CeO2 system remains limited. Herein, the pathways for hydrogen spillover on the surface of two Pt/CeO2(111) models have been systematically investigated using density functional theory (DFT) calculations. Hydrogen coverage and metal coverage are considered factors influencing hydrogen spillover in the Pt/CeO2 system. Descriptors for hydrogen migration at different metal coverages have been proposed to screen effective spillover metals within group Ⅷ: at lower metal coverages, the difference between [Eads(M−H)] and [Eads(O−H)] is considered as a descriptor, at higher metal coverages, the [Eads(M−H)] is used as a descriptor. Based on hydrogen spillover pathways, two dynamic mechanisms of hydrogen spillover, namely M–O–M and M–M, are introduced at different metal coverages. This study offers a deeper understanding of the hydrogen spillover phenomenon, proposes descriptors for hydrogen spillover and provides new insights into the design of heterogeneous catalysts.

Wu H., Chen Y., Jiao W., Dong M., Qin Z., Wang J., Fan W.

Lustemberg P.G., Yang C., Wang Y., Ganduglia-Pirovano M.V., Wöll C.

Qiao H., Zhang W., Zhang D., Yan W., Li J., Li Y.

Wang C., Lan J., Li M., Wang H., Xie F., Tian X., Gao T., Chen J., Yu Z., Schnell M., Grabow J., Gou Q.

Xu G., Yi Z., Liu H., Lai J., Di H., Lu Y., Huang H., Wang Z.

AbstractElectric double layer capacitors (EDLC) require large specific surface area to provide high power density. The generation of pores increases the electrochemical capacitance with more graphitic edge planes exposed to the electrolyte. Conventional theory believes this increasing in capacitance is owed to the increased specific surface area, but our work uncovers another mechanism. DFT calculations discover the commonly seen defect‐free zigzag and armchair edges can increase the quantum capacitance (CQ) due to their high chemical activity. Meanwhile, high chemical activity makes defect‐free edges interact with electrolyte molecules more easily, leading to the potential reduce of electrolyte stabilization and the change on the origin mechanism of double layer capacitance (CD). Additionally, edges with non‐hexagonal defects show a better balance between high CQ and electrolyte stability. Therefore, our discovery proves the preservation of non‐hexagonal defects in edge planes through possible temperature controlling in heat treatment is important in reaching high electrochemical properties for EDLC.

Tang C., Huang Q., Wang Z., Sun Y., Ding J., Wang F., Huang W., Wen X., Zhang Z.

Jiang W., Li X., Liu Y., Zhang C., Zhang G., Morsali A.

A practical approach is presented for the highly selective hydrogenation of various unsaturated compounds using a cutting-edge Ru/PNN catalytic system, resulting in high turnover numbers and substantial production of valuable pharmaceuticals.

Liu X., Li F., Ma M., Wang Y., Yang Z., Fang Y.

ABSTRACTEntrained‐flow bed gasification was an important way to realize clean coal conversion. However, the high calcium–iron coal ash had a low flow temperature, low viscosity, and strong fluctuations in viscosity, which severely affected the service life of the gasifier. It was necessary to regulate its ash fusion temperature and viscosity–temperature characteristics (AFV). In the paper, the AFV of Datong coal (DTC, a high calcium–iron coal) and its regulation mechanism were investigated by ash fusion temperature tester, high‐temperature viscometer, Raman spectrometer, differential scanning calorimetry, X‐ray diffractometer, FactSage software, and activation energy calculation. With the increasing Pingdingshan coal (PDS, a high silicon–aluminum coal) mass ratio, the AFV of DTC mixtures increased, and the viscosity fluctuation of DTC mixtures disappeared gradually. When PDS mass ratio is in the range of 18%–24%, the flow temperature and viscosity of DTC ash were 1375°C–1400°C and 18–22 Pa·s, respectively. The increasing PDS mass ratio, the formation of high melting point anorthite and its increasing content, the polymerization degree of DTC mixed ash increasing, and a gradual increase in activation energy as well as their corresponding crystallization behavior led to the increase in the AFV. The mineral transformations and the position variation in the ternary phase diagram of ash compositions with PDS addition by FactSage calculation also explained the variations in the viscosity–temperature characteristics.