Liquid-Phase Oxidation of Pentamethyldisilane with Oxygen

Russian Journal of General Chemistry -     

Supported Palladium Oxide Nanoparticles in SBA‐15 as a Heterogeneous Catalyst for the Aerobic Oxidation of Alcohols

Palladium nanoparticles were first synthesized through the thermal decomposition method and subsequently immobilized on ordered mesoporous silica material, SBA‐15, to afford PdO/SBA‐15 catalyst. The synthesized catalyst was characterized by X‐ray diffraction, nitrogen adsorption‐desorption measurement, transmission electron microscopy, and inductively coupled plasma atomic emission spectrometry. The catalytic activity was tested for the aerobic oxidation of alcohols. Easy recovery, high yeilds and relatively short reaction times were observed for the mentioned catalyst.     

Oxidation of Benzene in the Aqueous Phase Over a Bimetallic Carbon Supported Catalyst

Aqueous phase heterogeneous catalytic oxidation of benzene by dissolved oxygen is reported. Using a bimetallic platinum-ruthenium catalyst supported on a high surface area activated carbon, good conversions were obtained at temperatures above 100°C and space-times greater than 40 seconds. Complete conversion of benzene to carbon dioxide and water was achieved at 100°C with a reactor space-time of 300 s.     

A Supported Palladium on Gallium-based Liquid Metal Catalyst for Enhanced Oxygen Reduction Reaction

Developing high-performance catalysts for oxygen reduction reaction to replace costly platinum-based materials is of great importance but still confronted with challenges. Herein, a kind of supported palladium liquid metal catalyst, which is prepared by galvanic replacement, surpasses commercial Pt/C and Pd/C in oxygen reduction catalysis with a higher half-wave potential of 0.92 V, mass activity of 1.85 A/mg_Pd at 0.90 V, and superior durability. The liquid metal support can both optimize the electronic structures of Pd sites and guarantee the dispersion of Pd atoms, which explains the enhanced activity and durability, respectively. This work opens an avenue for rational design of catalysts.     

Dealloyed Silver Nanoparticles as Efficient Catalyst Towards Oxygen Reduction in Alkaline Solution

Silver nanoparticles(Ag NPs) were prepared by dealloying Mg-Ag alloy precursor. The obtained Ag NPs have an average ligament size of (50±10) nm. Electrocatalytic activity of Ag NPs towards oxygen reduction reaction(ORR) in 0.1 mol/L NaOH solution was assessed via cyclic voltammetry(CV), rotating ring disk elec-trode(RRDE) techniques, and electrochemical impedance spectroscopy(EIS). The electrochemical active area for the ORR was evaluated by means of the charge of the underpotential deposition(UPD) of lead(Pb) on Ag NPs. The CV results indicate that Ag NPs have a higher current density and more positive onset potential than the bulk Ag electrode. RRDE was employed to determine kinetic parameters for O₂ reduction. Ag NPs exhibit a higher kinetic current density of 25.84 mA/cm² and a rate constant of 5.45×10^-2 cm/s at -0.35 V vs. Hg/HgO. The number of electrons(n) involved in ORR is close to 4. Further, EIS data show significantly low charge transfer resistances on the Ag NPs electrode. The results indicate that the prepared Ag NPs have a high activity and are promising catalyst for ORR in alkaline solution.     

Liquid-Phase Methane Peroxidation in the Presence of Cu-ZSM-5: Effect of Modification with Palladium

Kinetics and Catalysis - The properties of Pd-modified Cu-ZSM-5 catalysts in liquid-phase methane peroxidation have been studied. The catalysts were prepared by polycondensation of Cu2+ and Pd2+...     

铂、钯负载型活性催化剂的制备及其对一氧化碳的催化氧化活性

用浸渍法分别将铂、钯负载在铝柱撑蒙脱石载体上,制备了铂、钯负载铝柱撑蒙脱石催化剂。运用X射线衍射(XRD)、原子吸收光谱(AAS)、透射电镜(TEM)等分析方法对样品的性能和结构进行了表征,并考察了不同铂、钯负载量的催化剂对一氧化碳的催化氧化性能。结果表明,铂、钯均以高度分散的纳米粒子状态均匀分布在载体表面,并表现出良好的CO催化氧化活性。铂、钯在铝柱撑蒙脱石载体表面的有效负载率在70%~76%之间,在相同的设计负载量条件下,铂的实际负载量和有效负载率均略大于钯。CO催化氧化试验结果表明,相对于负载前,负载后催化剂的催化活性明显增加,且其催化活性随着铂、钯负载量的增加而不断增强。在相同温度和负载量条件下,钯负载型催化剂的催化活性明显高于铂负载型催化剂。     

Palladium Supported on Porous Organic Polymer as Heterogeneous and Recyclable Catalyst for Cross Coupling Reaction

Palladium immobilized on an amide and ether functionalized porous organic polymer (Pd@AEPOP) is reported to be an effective heterogeneous catalyst for the Heck cross-coupling reaction of aryl iodides with styrene for the synthesis of diphenylethene derivatives. Excellent yields can be obtained using a 0.8 mol% Pd catalyst loading under the optimized reaction condition. The heterogeneous Pd@AEPOP catalyst can also be applied on the Suzuki reaction and the reduction of nitroarene.     

Sodium Cobalt Metaphosphate as an Efficient Oxygen Evolution Reaction Catalyst in Alkaline Solution

Sodium cobalt metaphosphate [NaCo(PO₃)₃] has CoO octahedra (CoO₆) and shows superior oxygen evolution reaction (OER) activity in alkaline solution, comparable with the state‐of‐the‐art precious‐metal RuO₂ catalyst. OER catalysts of this metaphosphate are prepared by combustion (Cb) and solid‐state (SS) methods. The combustion‐assisted method offers a facile synthesis and one‐step carbon composite formation. Unusually high catalytic activity was observed in NCoM‐Cb‐Ar and could be due to chemical coupling effects between NaCo(PO₃)₃ and partially graphitized carbon. This novel electrocatalyst exhibits very small overpotential of 340 mV with high mass activity of 532 A g^?1. Good charge transfer abilities and chemical coupling between NaCo(PO₃)₃ and amorphous carbon gives the OER activity in NCoM‐Cb‐Ar.     

碱性水溶液中ABEI的电致化学发光的研究

研究了6-[N-(4-氨基丁基-N-乙基)-N-乙基]-氨基-2,3-二氢吩噻嗪1,4-二酮(ABEI)的电致化学发光的各种条件,发现最佳的电脉冲参数为:占空比0.45,脉冲周期20ms,脉冲幅值+1.6V(相对饱和甘汞电极);最佳介质是0.12mol/L KOH-0.080mol/L H_3BO_(3-)0.080 mol/L KCI(pH12.0).在这些条件下,ABEI的发光强度与浓度在1.0×10~(-8)～9.0×10~(-5)mol/L范围内呈线性关系.研究表明,溶液中的Cl~-先被氧化为CIO~-,CIO~-再与ABEI作用并使其发光.     

双浸渍法制备负载型钯催化剂

益气回阳注射液由人参、制附子、枳实等制成。在大鼠肠系膜上动脉半塞性休克时，益气回阳注射液能使平均动脉压及脉压差增大，提高全血及心、肝、肾组织的ＧＳＨ－Ｐｘ活性。     

介孔Fe/SBA-15非均相芬顿氧化水中难降解染料罗丹明B

以介孔二氧化硅SBA-15 为载体, 采用等体积浸渍法制备了Fe/SBA-15. 通过X射线衍射(XRD)、N₂吸附-脱附、扫描电镜(SEM)、透射电镜(TEM)和X射线光电子能谱(XPS)等技术对其进行了表征, 并用于对水溶液中罗丹明B (RhB)的芬顿氧化. 表征结果表明了Fe/SBA-15维持了长程有序的介孔结构, 孔径和比表面积都有所下降, 并呈现棒状体的聚集态, 平均直径为0.6 μm. Fe 以α-Fe₂O₃的形态同时存在于介孔孔道内外. 在Fe/SBA-15 和H₂O₂同时存在条件下RhB的去除是吸附和催化氧化降解的协同作用所致, 并且与Fe/SBA-15 投加量密切相关, 但与初始溶液pH 几乎无关. 当Fe/SBA-15 投加量为0.15 g·L^-1, RhB 初始浓度为10.0 mg·L^-1,H₂O₂/Fe³⁺摩尔比为2000:1,初始溶液pH为5.4和反应温度为21 ℃时, RhB去除率达到了93%. Fe/SBA-15的Langmiur 单分子层饱和吸附量为99.11 mg·g^-1. 此外, 采用H₂O₂浸泡方式对使用过的Fe/SBA-15可进行再生,连续6 次循环使用后仍可维持80%的RhB去除率, 且每次使用后Fe浸出浓度都在0.1 mg·L^-1 (或者0.6% (质量分数))以下. 基于淬灭实验、UV-Vis 光谱和气相色谱-质谱(GC-MS)联用仪分析的结果, 提出了RhB的去除机理. 非均相芬顿催化剂Fe/SBA-15可用于去除像RhB这样的生物难降解有机物.     

超细Fe-V-O催化剂上甲苯液相氧化制苯甲醛

分别采用共沉淀法,凝胶自燃烧法和水热法制备了Fe-V-O复合氧化物催化剂用于催化过氧化氢液相氧化甲苯制苯甲醛反应中,并采用N2等温吸附-脱附法,粉末X射线衍射,红外光谱,扫描电子显微镜,能量弥散X射线光谱和H2程序升温还原等方法对催化剂性质进行了表征.结果表明,制备方法显著影响催化剂的结构,比表面积,形貌,表面元素组成和还原性.Fe-V-O催化剂颗粒的超细化调变了其比表面积和还原性,从而改善了催化剂上甲苯液相氧化制苯甲醛反应性能.其中水热法制备的超细Fe-V-O催化剂具有最高的苯甲醛收率和较好的重复使用性能.这主要归因于该催化剂颗粒尺寸小,比表面积大,以及表面较多的活性钒氧物种和适宜的还原性.     

负载钯催化剂上亚硝酸乙酯的催化分解

 研究了亚硝酸乙酯在不同载体及负载钯催化剂上的分解行为．结果显示，固体酸性中心和金属钯中心都可以催化亚硝酸乙酯的分解反应．在C2H5ONO与CO合成草酸二乙酯的反应中，亚硝酸乙酯是在固体催化剂表面发生分解，而不是在气相发生热裂解．并且，该反应的活性与亚硝酸乙酯的分解程度不存在正比关系．通过对分解产物的分析，提出了亚硝酸乙酯在固体催化剂上分解的连续脱氢机理．