深度加氢脱硫催化剂载体效应的研究进展

综述了近年来深度加氢脱硫催化剂载体的研究进展,主要介绍了单一氧化物载体、复合氧化物载体、酸性载体以及炭材料等其他载体对深度加氢脱硫催化剂活性的影响。单一氧化物载体容易与活性组分作用生成没有催化活性的相,从而影响催化剂的活性;复合氧化物载体可以克服单一氧化物载体的缺陷,从而使制备的催化剂对芳烃的加氢和对二苯并噻吩及它的芳烃衍生物的转化具有较好的效果;对芳香烃大分子硫化物的脱除,酸性载体比其他载体具有不可比拟的优势;炭材料等新型载体与金属活性组分的相互作用可达到最小,从而可以充分发挥金属活性组分的作用。

SCR脱除NO_x催化剂的研究进展

NO_x排放对人体和环境造成较大危害。SCR脱硝技术已成为减少NO_x排放的主流技术,在SCR脱硝技术中催化剂占有重要作用,开发出具有高活性、高稳定性和高寿命的催化剂至关重要。阐述了金属氧化物载体、分子筛载体以及碳载体催化剂的选择性催化还原法脱除NO_x的研究进展,对SCR脱硝催化剂研究领域存在的问题进行探讨,并展望了今后研究方向。

Recent progress on oxygen and hydrogen peroxide reduction reactions on Pt single crystal electrodes

The oxygen reduction reaction(ORR)is probably the most important cathodic process in electrocatalysis because of its universal role as comburent in life and key applications in several fields such as fuel cells,corrosion processes or lithium-air batteries.Despite many experimental and theoretical investigations that have been carried out during the last years and contributed to improve the knowledge about this reaction,the complete mechanism for the ORR is not elucidated yet[1].The ORR involves the exchange of 4 electrons and 4 protons for the complete reduction of O2 to water(Eq.1).The reaction mechanism is complex and implies the formation of several intermediates involving O=O bond scission and O–H bond formation.

Boosting chiral carboxylic acid hydrogenation by tuning metal-MO_(x)-support interaction in Pt-ReO_(x)/TiO_(2) catalysts

Engineering the surface microenvironment by tuning the binary interactions between a supported metal with a secondary metal oxide(MO_(x))or support has been a common method for improving the catalytic performance of supported metal catalysts.However,few studies have investigated the ternary interactions among the metal,MO_(x),and support.Here,we report for the first time the formation of metal-MO_(x)-support interaction(MMSI)in reducible TiO_(2)-supported PtReO_(x) catalysts,affording 87% yield and 100% ee in the tandem hydrogenation of an aqueous chiral cyclohexane-1,2-dicarboxylic acid into the corresponding diol;the catalytic activity is eight times higher than that obtained with non-reducible support counterparts in the same reaction via traditional batch synthesis with multiple steps and unfriendly reagents.Detailed experimental and computational studies suggest that the TiO_(2) crystalline phase-dependent density of the oxygen vacancies induces different Pt-ReO_(x)-TiO_(2) interactions,which dominate the electron transfer therein and tune the adsorption strength of the carbonyl moiety of the substrate/intermediate,thus promoting the hydrogenation activity and selectivity.In addition,the strong MMSI endows the optimal rutile TiO_(2) supported PtReO_(x) catalyst with an outstanding lifetime of 400 h in a fixed-bed reactor under acidic aqueous conditions and ensures efficient applications in the selective hydrogenation of aliphatic dicarboxylic acids and functional carboxylic acids.This work provides a promising strategy for the development of efficient and stable supported catalysts for the selective hydrogenation of diverse C-O and C=O bonds.

Correlation between catalytic activity of supported gold catalysts for carbon monoxide oxidation and metal–oxygen binding energy of the support metal oxides

The effect of a wide variety of metal oxide （MOx） supports has been discussed for CO oxidation on nanoparticulate gold catalysts. By using typical co‐precipitation and deposition–precipitation methods and under identical calcination conditions, supported gold catalysts were prepared on a wide variety of MOx supports, and the temperature for 50%conversion was measured to qualita‐tively evaluate the catalytic activities of these simple MOx and supported Au catalysts. Furthermore, the difference in these temperatures for the simple MOx compared to the supported Au catalysts is plotted against the metal–oxygen binding energies of the support MOx. A clear volcano‐like correla‐tion between the temperature difference and the metal–oxygen binding energies is observed. This correlation suggests that the use of MOx with appropriate metal–oxygen binding energies （300–500 kJ/atom O） greatly improves the catalytic activity of MOx by the deposition of Au NPs.

Promoting NO_(x)reduction via in situ activation of perovskite supported Pd catalysts under alternating lean-burn/fuel-rich operating atmospheres

Herein,we report the excellent De-NO_(x)performance of La0.7Sr0.3MnO3(LSM)perovskite-supported Pd catalysts(Pd-LSM)in alternating lean-burn/fuel-rich atmospheres using C3H6 as reductant and describe the in situ activation of the Pd catalysts via metal-support interaction(MSI)tuning.The NO_(x)reduction conversion of the Pd-LSM catalyst increased significantly from 56.1%to 90.1%and the production of N2O was suppressed.Our results demonstrated that this behavior was mainly attributed to the in situ transformation of Pd2+into Pd0 during the reaction.The generated Pd0 species could readily activate the C3H6 reductant and achieve an eight-fold higher turnover frequency than Pd2+for the reduction of NO_(x).Moreover,excessive MSIs inhibited the in situ generation of Pd0,and thereby,lowered the De-NO_(x)activity of the catalyst even at high Pd dispersion.In addition,the Pd-LSM catalysts exhibited much higher S tolerance than conventional Al_(2)O_(3)-supported catalysts.Our study provides a new approach for analyzing and designing highly active metal catalysts operated under dynamic alternating oxidizing/reducing atmospheric conditions.

Effective Channel Length Degradation under Hot-Carrier Stressing

This article describes the effective channel length degradation under hot carrier stressing. The extraction is based on the IDs-Vcs characteristics by maximum transconductance （maximum slope of IDs ＆ VGS） in the linear region. The transconductance characteristics are determine for the several devices of difference drawn channel length. The effective channel length of submicron LDD （Lightly Doped Drain） NMOSFETs （Metal Oxide Semiconductor Field Effect Transistor） under hot carrier stressing was measured at the stress time varying from zero to 10,000 seconds. It is shown that the effective channel length was increased with time. This is caused by charges trapping in the oxide during stress. The increased of effective channel length （△Leff） is seem to be increased sharply as the gate channel length is decrease.