## 留言板

In our previous work, high tar yield was achieved by coal pyrolysis coupled with steam reforming of methane (CP-SRM), but the tar has high content of heavy fractions. In order to improve the tar quality by decreasing the heavy tar content and ensuring high tar yield, in-situ catalytic upgrading of tar from the integrated process of coal pyrolysis coupled with steam reforming of methane was conducted over carbon (KD-9) based Ni catalyst. The results showed that at 650 oC, the tar yield of CP-SRM over 5Ni/KD-9 is 24.4%, which is a little lower than that of without catalyst, while the light tar yield (i.e.,18.9%) is 1.4 times higher than that of without catalyst, and the content of C2, C3 and C4 alkyl used as a substitute for benzene significantly increases tar yields by 0.5, 0.6 and 4.0 times, respectively. The content of phenols and naphthalenes in tar also increased dramatically after upgrading. Isotope tracer approach combined with the mass spectra of typical components was employed in exploring the mechanism of the upgrading process. The results showed that 5Ni/KD-9 catalyzes coal tar cracking and SRM at the same time. Small free radicals such as ·CHx, ·H and ·OH generated by SRM can combine with free radicals from tar cracking, thus avoiding excessive cracking of tar.

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.

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.

β−O−4醚键是木质素结构中含量最丰富的单元间连接键型，研究高效断裂β−O−4的催化体系对木质素解聚制备单酚具有重要意义。本研究以β−O−4型二聚体模型化合物为原料，结合GC-MS、GC-FID、HSQC NMR表征手段，考察碳负载金属催化剂、反应温度、时间、氢气初始压力等因素对二聚体β−O−4键的断键活性以及单体收率的影响。结果表明，NaOH与碳负载金属催化剂存在协同作用，可以增强β−O−4断键活性。其中，NaOH与Pd/C协同效果最佳，二聚体解聚单体产物从44.1%提高至83.4%。机理研究表明，NaOH协同Pd/C能有效抑制二聚体发生Cα羟基的脱除，显著提升二聚体β−O−4的断键选择性，从而提高了单体产物的收率。NaOH协同Pd/C催化体系对其他醚键（α−O−4）同样存在优异的断键能力。因此，在所做实验的最佳条件下，NaOH协同Pd/C催化体系能高效解聚碱木质素制备单酚化合物，单体产物收率高达37.5%，苯甲醇类选择性高达48.8%。

Catalytic cracking of triglycerides and their derivatives (e.g., fatty acid methyl esters, FAMEs) by HZSM-5 zeolite offers a promising route to produce renewable aromatics and olefins, but it is primarily hindered by the rapid catalyst deactivation caused by coke. In this work, the co-cracking of FAMEs and methanol over HZSM-5/Al2O3 composites was developed to regulate the product distribution and slower the catalyst deactivation. Co-feeding methanol with FAMEs enhanced the olefin selectivity at the expense of aromatics, and the total selectivities of aromatics and olefins added up to 70.9% with an optimized methanol content of 60%. The co-feeding of methanol not only promoted the olefin yield but also retarded the consecutive H-elimination of aromatics to polycyclic aromatics, thus reducing the coke formation and prolonging the catalyst lifespan. Under the conditions of 450 °C, 0.16 MPa and a space velocity of FAMEs at 4 h−1, increasing the methanol blending ratio in FAMEs from zero to 50% reduced coke from 17.8% to 10.1% after reaction for 12 h. Besides, the spent catalyst for the co-cracking reaction could be easily regenerated by coke combustion, yielding similar structure, acidity and activity to those of the fresh one.

Catalytic lignin depolymerization (CCLD) for liquid fuels and phenolic monomers was investigated over various supports including clays (e.g., sepiolite (SEP), attapulgite (ATP), and montmorillonite (MTM)), and oxides (e.g., Al2O3 and SiO2) as well as their supported Mo-based catalysts under supercritical ethanol. The characterization results demonstrated that different supports with diverse structural properties could affect the textural structures, surface Mo5+ content, and acid sites distribution. Clay-based supports had more strong acid sites as compared with Al2O3 and SiO2, which went against the production of lignin oil (LO) and led to form more solid products during CLD experiments. Meanwhile, the obtained petroleum ether-soluble product (PEsp) in LO catalyzed by sole supports was mainly alkyl/alkoxy substituted phenols. Additionally, Mo species (especially Mo5+) significantly increased the yields of LO and PEsp. Mo/SiO2 had the highest surface Mo5+ species, showing the highest LO yield of 85.2%, in which the produced alkyl/alkoxy substituted phenols reached 450.3 mg/glignin. Among the clay-supported Mo catalysts, Mo/SEP presented superior LO (82.3%) and PEsp (70.8%) yields and the generated substituted phenols reached 398.8 mg/glignin. This paper systematically reported the application of green and environmentally friendly clay-based materials in lignin conversion, which provides some key information for the development of clay catalysts for biomass conversion.

“碳达峰、碳中和”目标的提出，为中国能源结构转型提供了动力引擎。发展生物质基高密度燃料，既可以为传统石油基高密度燃料提供可再生的替代品，又符合中国可持续发展以及能源结构转型的要求。本文综述了RJ-4、JP-10等典型石油基高密度燃料的性质和用途，总结了由萜类以及木质纤维素平台化合物合成RJ-4、JP-10以及其他多环燃料的路线方法，展示了生物质转化制备高密度燃料的良好可行性，讨论了目前生物质基高密度燃料研究面临的瓶颈以及发展方向。

Versatile and environmentally benign dimethyl carbonate (DMC) synthesized by propylene carbonate (PC) and methanol via transesterification is green and energy efficient. A series of solid base catalysts derived from F-Ca-Mg-Al layered double hydroxides (LDHs) with different NaF amount were prepared, characterized and tested for the transesterification reaction. The properties of the catalysts modified by fluorine have improved obviously. The catalytic activity increases in the order of: FCMA-0.8 > FCMA-0.4 > FCMA-1.2 > FCMA-1.6 > FCMA-0, which is consistent with the total basic sites amount and the strong basic sites amount. FCMA-0.8 has the best catalytic activity as pure CaO catalyst, and the PC conversion, DMC selectivity and DMC yield are 66.8%, 97.4% and 65.1%, respectively. Furthermore, the DMC yield for FCMA-0.8 just decreased 3.9% (33.2% for CaO catalyst) after 10 recycles. FCMA-0.8 has good prospects in the transesterification of PC with methanol to DMC for industrial application.

Deposition or slagging problem caused by the alkali metal species is one of the major obstacles to utilize biomass fuel in combustion and gasification plant. The paper mainly studies the effect of water leaching on alkali-induced slagging properties of corn straw and rice straw. The original mineral form of alkali elements in biomass straw was studied with comparison of low temperature ash of biomass before and after water leaching. The release and transformation of alkali compounds in biomass straw at different temperatures during heating were analyzed with combination of the XRD result of the heated biomass and the chemical composition of the digested samples. The result shows that the potassium in corn and rice straw mainly exists in the form of KNO3, KClO4, K2SO4 and KAlSi3O8, in which KNO3, K2SO4 and KClO4 is mostly removed in water leaching. The fusion temperatures increased after water leaching, especially for rice straw ash, which is a typical sample that the basic compounds are mainly potassium-containing compounds. The decrease of potassium content with temperature in the original corn and rice was because the potassium-containing minerals decomposed and escaped at 25−1000 °C. The release of potassium in the range of 400−800 °C significantly reduced for corn and rice straw after water leaching, but the potassium content will still decrease above 800 °C. The decrease of magnesium content in corn with increasing temperature may be due to the volatilization of magnesium oxide under the action of carbon reduction. For fuels with high alkali metal content after water leaching, the residual alkali metal will still escape and cause deposition or slagging in the furnace, especially in the temperature range above 800 °C.

The dehydrogenation performance of vanadyl catalysts was closely related to the form of surface vanadyl species. To enhance the vanadium dispersion, phosphorus was adopted to modify V-MCM-41 catalysts by using organic vanadium and phosphorus precursors. The influence of phosphorus introduction to the mesoporous structure and vanadyl species were investigated by various characterization techniques. The results showed that the catalysts could maintain ordered hexagonal mesoporous structures though the specific surface area slowly decreased along with the increase of phosphorus content. Both the reducibility and dispersion of the surface vanadyl species were improved. The proportion of polymerized vanadyl species obviously decreased due to the presence of phosphorus species. The propane dehydrogenation reaction results showed that both the catalytic performance and the catalyst stability were improved. Both the maximum surface vanadyl site density and optimum propane dehydrogenation performance were obtained over the sample with Si/P molar ratio of 30.

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−1h−1 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.

H-[B,Al]-ZSM-5 zeolites were synthesized with glucose as assistant template to catalyze methanol converting toward propylene. The superior catalytic performance in terms of the propylene selectivity and the activity longevity was related to high ratio of weak acid to strong acid for favorable production of propylene and to high mesoporosity for improved diffusion of reactants and prevention from fast coking. More framework Al siting in the straight or sinusoidal channels of the MFI zeolite could also enhance the propylene/ethylene ratio due to the promotional effect on propylene formation. Low weak acid density was conducive to the production of high propylene/ethylene ratio. With the B/Al ratio of 2 and the (Al2+B2)/Si ratio of 0.01, HZ5-G-2B was applied in the methanol to propylene reaction at CH3OH/H2O (1/1.2) WHSV of 1.8 h−1 and 480 °C. Propylene selectivity of 51.6%, the ${\rm{C}}_{2}^ {=}$${\rm{C}}_{4}^ {=}$ selectivity of 83.7%, and complete conversion of methanol were achieved. The propylene/ethylene ratio was 2. The catalytic activity kept stable for 580 h.

Recently, a new carbon nitride (C3N5) photocatalyst has attracted much attention due to its excellent light harvesting and unique 2D structure. However, high recombination rates of electron-hole pairs of bulk C3N5 serious affect the photocatalytic performance. Herein, nickel oxide (NiO) modified C3N5 p-n junctions photocatalyst was synthesized by a facile hydrothermal method. Results indicated that the 9-Ni/C3N5 nanosheet photocatalyst showed excellent hydrogen production efficiency under visible light. The hydrogen production rate reached 357 μmol/(g·h), which was 107-fold higher than that of pristine C3N5. The high catalytic performace was attributed to the 9-Ni/C3N5 p-n junctions which could efficiently promote photogenerated electron–hole pair separation and thus promote the hydrogen evolution reaction.

Conductive carbon film has a wide range of application prospects, especially in the fields of electric heating devices, energy storage devices, and solar cells. Coal tar is an ideal precursor for preparing carbon film. In order to improve the performance of coal tar-based carbon film, it is necessary to study the influence of tar composition on the structure and performance of carbon film. In this paper, a carbon film is prepared using aromatic compounds, heteroatom compounds and tar as carbon sources. It is found that the carrier concentration of aromatic hydrocarbon-based carbon films is higher than 1022/cm3, but the mobility of the carrier is lower than 1 cm2/Vs. The resistivity and sheet resistance of the aromatic hydrocarbon-based carbon film are lower than that of the coal tar-based carbon film. Naphthalene-based carbon film has the best electrical and thermal properties. The maximum heating temperature of naphthalene-based carbon film at 30 V exceeds 300 °C. The thickness of the carbon film has a decisive influence on the sheet resistance of the carbon film. The performance of the heteroatom compound-based carbon film is significantly lower than that of aromatic compound-based film.

The effects of pretreatment methods (DR, R, ROR) on the microstructure of Co/SiO2 catalysts and the activity for Fischer-Tropsch synthesis (FTS) were investigated. The pretreated catalysts were characterized by TEM, HRTEM, XRD, XPS, H2-TPD, TG and TPR. The results showed that after the pretreatments, specific morphological of the Co species changed, forming new Co active surface species. The Co particles redispersed and the Co species was facile to be re-reduced. The Co/SiO2 catalysts pretreated by different method showed different catalytic performance. The catalyst treated by the reduction-passivation had higher activity and ${\rm{C}}_{5}^ {+}$ selectivity for FTS.