## 留言板

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.

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.

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·h) 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.

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.

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℃, 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.

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 ${\rm{C}}_{{2-4}}^ {=}$ 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.

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.

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.

CO活化是费托反应的关键步骤，其解离方式一直是人们争论的焦点。本文用溶剂热法合成了三种暴露不同晶面的Co基催化剂，排除载体、助剂、晶粒尺寸等参数的影响，通过程序升温脱附、原位拉曼、原位漫反射红外等表征手段和化学瞬变反应技术，对不同晶面Co催化剂在费托反应过程中CO活化行为进行了探究。结果表明，CO的活化在不同晶面的Co基催化剂上具有结构敏感性。Co（10-11）晶面上CO以直接解离的方式进行活化，且CO解离生成的碳物种部分形成积碳，其余碳物种加氢生成CHx；Co（0001）晶面上CO以氢助解离的方式活化，大量解离为积碳，少量碳物种氢化为CHx；Co（11-20）晶面上CO直接解离，该催化剂上CO弱解离得到微量的积碳，其余碳物种在氢的存在下生成微量的CHx中间体。

With the problem of ammonia leakage in traditional denitration methods becoming more and more obvious, ammonia-free denitration technology has become a research hotspot topic recently. In a fixed-bed reactor, the direct reduction of NO by copper and potassium bimetallic supported coconut shell activated carbon in aerobic and anaerobic environments was investigated under temperature-programmed surface reaction (TPSR) conditions. The materials were characterized using BET, SEM, XRD, XPS, H2-TPR, Raman and FT–IR. The experimental results showed that the active functional groups formed on the surface of carbon materials were the important intermediate products and played a key role in the reduction process. The addition of oxygen could greatly promote the formation of intermediate C(O) (Oxygen-containing functional groups on the carbon surface), so the reduction rate of NO could be increased. Furthermore, the effect of bimetallic oxide catalysis was obvious in the direct reduction of NO. When copper: potassium= 2∶1, the denitration rate could reach 90% at 300 °C. The synergistic catalytic reduction of bimetallic had a significant effect on reducing the reaction temperature window. Based on the experimental results, the catalytic activity mainly came from the redox cycle of CuO/Cu2O, and the potassium inhibited the agglomeration of copper on the surface of carbon materials.

Activating C−H bonds of CH4 is a key bottleneck step of the conversion of methane to chemical commodities. Loading Ni onto ZrO2 is regarded as a relatively efficient way to harness the beneficial electronic property and the fine dispersion of the Ni catalyst for CH4 dissociation. Herein we demonstrate the promising role of Ni catalyst supported on ZrO2 for obtaining very active CH4 dissociation, with results comparable to Ni13. The density functional theory (DFT) results show that the ZrO2 supported Ni13 stabilizes all species better and facilitates CH4 activation. The stepwise dehydrogenations of CH4, with ZrO2, on Ni13-ZrO2(111), correspond to the extended C−H bond lengths of ISs, the lower Ea, the smaller displacements between the detaching H and the remaining CHx fragment in TSs, as well as being higher exothermic. However, without the ZrO2 support on Ni13, the opposite happens. Consequently, the ZrO2 modified Ni13 exhibits superior activity with respect to the original Ni13 in CH4 dehydrogenation. The electronic analysis combining DFT calculations have ascertained that it is the larger overlap between C2p and Ni3d as well as the growing electron transfer Ni→C that cause the weaker C2p−H1s hybridization, In addition, this also cause the reduction of electron transfer H→C, thus leading to a stronger interaction between Ni and C along with a weak C−H bond. Hence, the ZrO2 support is revealed as playing the role of the d-band electron reservoir at Ni13 to activate C−H bonds for catalytic CH4 dehydrogenation.

2021, 49(12): 1-2.

2021, 49(12): 1-10.

2021, 49(12): 1733-1751.   doi: 10.1016/S1872-5813(21)60134-2

2021, 49(12): 1752-1767.   doi: 10.1016/S1872-5813(21)60135-4

2021, 49(12): 1768-1779.   doi: 10.19906/j.cnki.JFCT.2021063

2021, 49(12): 1780-1790.   doi: 10.19906/j.cnki.JFCT.2021076

“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。

2021, 49(12): 1791-1801.   doi: 10.1016/S1872-5813(21)60086-5

2021, 49(12): 1802-1811.   doi: 10.1016/S1872-5813(21)60087-7

2021, 49(12): 1812-1820.   doi: 10.19906/j.cnki.JFCT.2021064

2021, 49(12): 1821-1831.   doi: 10.1016/S1872-5813(21)60150-0

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