Reductive amination of furfural toward furfurylamine with aqueous ammonia under hydrogen over Ru-supported catalyst

Poly(N-vinyl-2-pyrrolidone)-capped ruthenium-supported hydroxyapatite (Ru-PVP/HAP) shows significant activity for the synthesis of furfurylamine (FAM) via the reductive amination of furfural. As-prepared 5 wt% Ru-PVP/HAP affords 50 % yield of FAM in 25 % NH₃ aqueous solution under pressurized H₂ gas (2.5 atm), and the highest yield approaches 60 % at 4.0 H₂ atm. Comparison between the activities over four Ru-supported HAP catalysts prepared with different methods and the results of X-ray absorption spectroscopy suggested that the metallic Ru cluster is the active center for the reductive amination of furfural. Transmission electron microscope and inductively-coupled plasma analysis indicated that the as-prepared 5 wt% Ru-PVP/HAP catalyst possessed 4.0 wt% PVP-capped Ru clusters with average diameter of 1.7 ± 0.3 nm on HAP support. It was also demonstrated that the reductive amination approach with Ru-PVP/HAP catalyst, NH₃ aq. and pressurized H₂ gas has capability for transformation of aromatic aldehydes to the corresponding aromatic amines. According to these results, it is concluded that Ru(0) cluster supported on HAP will represent a suitable catalyst for widely-usable reductive amination to convert an aldehyde functionality towards an amine.     

Direct synthesis of hydrogen peroxide from hydrogen and oxygen over insoluble Pd<Subscript>0.15</Subscript>M<Subscript>2.5</Subscript>H<Subscript>0.2</Subscript>PW<Subscript>12</Subscript>O<Subscript>40</Subscript> (M = K,Rb, and Cs) heteropolyacid catalysts

Palladium-containing insoluble heteropolyacid (HPA) catalysts (Pd_0.15M_2.5H_0.2PW₁₂O₄₀) were prepared by an ion-exchange method using various alkaline metal ions (M = K⁺, Rb⁺, and Cs⁺) (denoted as Pd-KPW, Pd-RbPW, and Pd-CsPW). They were then applied to the direct synthesis of hydrogen peroxide from hydrogen and oxygen. Conversion of hydrogen over the catalysts was almost identical with no great difference, while selectivity for hydrogen peroxide increased in the order of Pd-KPW < Pd-RbPW < Pd-CsPW. As a consequence, yield for hydrogen peroxide increased in the order of Pd-KPW < Pd-RbPW < Pd-CsPW. It was found that yield for hydrogen peroxide increased with increasing Pd 3d_5/2 binding energy of the catalyst. Among the catalysts tested, Pd-CsPW catalyst with the highest Pd 3d_5/2 binding energy showed the highest yield for hydrogen peroxide.     

FePO<Subscript>4</Subscript>/SiO<Subscript>2</Subscript> Catalysts for Propylene Glycol Oxidation

FePО₄/SiO₂ supported catalysts with a different content of iron phosphate are prepared. The properties of the catalyst are changed by the introduction of alkali metal compounds (Na or Cs) on its surface. The samples obtained are characterized by X-ray diffraction, low-temperature nitrogen adsorption, temperatureprogrammed reduction by hydrogen, and temperature-programmed desorption of ammonia. The catalytic properties are investigated in the reaction of gas-phase propylene glycol oxidation. It is shown that the selectivity of methylglyoxal formation on the unmodified catalysts is determined by the state of the supported active component and by its reduction–oxidation ability under the action of a reaction mixture.     

Cracking of Cellulose over Supported Metal Catalysts

Cellulose is cracked over supported Pt or Ru catalysts under hydrogenolysis conditions in water to give sorbitol as a main product. Among the catalysts tested, Pt/γ-Al₂O₃ gave the highest yield and selectivity, and this catalyst was recyclable in repeated runs. It is proposed that cellulose is hydrolyzed by in situ generated acid sites to form glucose, and glucose is immediately reduced to sorbitol over the metal catalyst.     

炭载钌催化剂的微波制备及其水相乙酰丙酸加氢性能

生物质衍生物乙酰丙酸是生物质转化过程中重要的平台分子,对其进行催化加氢可以得到高附加值的产物,是连接生物质转化和石油化工的重要途径。本实验研究了无溶剂微波辅助热解法绿色制备负载型钌基催化剂,以Ru₃（CO）₁₂为金属前体,碳纳米管、椰壳活性炭和活性氧化铝为催化剂载体,该制备方法简单易操作,环保高效低能耗,不使用溶剂,避免了杂质的引入和对催化剂的污染,是一种新型负载型贵金属催化剂的制备方法。同样采取传统浸渍法制备Ru/γ-Al₂O₃-IM。在乙酰丙酸水相催化加氢反应中的催化活性顺序为Ru/AC > Ru/CNT ≈ Ru/FCNT > Ru/γ-Al₂O₃-MW ≈ Ru/γ-Al₂O₃-IM。比较不同反应溶液水、甲醇、乙醇、苯甲醚、环己烷和丙酮等对于乙酰丙酸催化加氢反应的影响,并通过考察反应温度、反应压力和反应物初始浓度等因素对加氢反应的影响,确定最佳实验条件为：反应温度为90℃,反应压力2.0 MPa,适宜反应物浓度为0.10 g/mL,产品GVL收率大于99%。     

Fischer–Tropsch synthesis: evaluation of Gd and Ru promoters effect on Co/<Emphasis Type="Italic">γ</Emphasis>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst at different conditions

In this study, the effect of Ru and Gd promoters on 15Co/\(\gamma\)-Al₂O₃ catalyst in the Fischer–Tropsch synthesis is investigated. The catalysts were synthesized by dry impregnation method and characterized by XRD, adsorption/desorption of nitrogen, TPR, TEM, ICP and XPS analyses. Activity and selectivity of the catalysts were examined in a fixed bed reactor at 210–230 °C with a H₂/CO ratio of 2 and atmospheric pressure. The results showed that the Ru-promoted catalyst has the highest activity and methane selectivity which reduce the chain growth probability. The Gd-promoted catalyst was shown smaller particle size and higher dispersion of cobalt particles in compared with unpromoted catalyst. The smaller particles have more interaction and thus show the lower catalyst reducibility. The presence of Gd in the catalyst cause higher chain growth probability compared to the unpromoted one. The Ru–Gd-promoted catalysts were shown a synergic effect in the catalyst reducibility. Based on the screening of the catalysts in the atmospheric pressure; the unpromoted, 0.1Ru/15Co/Al₂O₃, and 0.1Ru1Gd/15Co/Al₂O₃ catalysts were selected to test at high pressure conditions, which the 0.1Ru1Gd/15Co catalyst showed the highest C₅ ⁺ selectivity (75%) compared with the 0.1Ru/15Co/Al₂O₃ and the unpromoted one.     

Highly stable and selective Ru/NiFe_2O_4 catalysts for transfer hydrogenation of biomass-derived furfural to 2-methylfuran

Spinel ferrites NiFe_2O_4 supported Ru catalysts have been prepared via a simple sol–gel route and applied for converting biomass-derived furfural to 2-methylfuran. The as-prepared catalysts were characterized by thermogravimetric analysis(TG), N_2 adsorption–desorption, X-ray diffraction(XRD), scanning electronic microscopy(SEM), and X-ray photoelectron spectroscopy(XPS). Results showed that the catalysts had well-dispersed Ru active sites and large surface area for calcination temperature ranging from 300 to 500 ℃. The conversion of biomass-derived furfural into 2-methylfuran was conducted over Ru/NiFe_2O_4 through catalytic transfer hydrogenation in liquid-phase with 2-propanol as the hydrogen source. A significantly enhanced activity and increased 2-methylfuran yield have been achieved in this study. Under mild conditions(180 ℃ and 2.1 MPa N_2), the conversion of furfural exceeds 97% and 2-methylfuran yield was up to 83% over the catalyst containing 8 wt% Ru. After five repeated uses, the catalytic activity and the corresponding product yield remained almost unchanged. The excellent catalytic activity and recycling performance provide a broad prospects for various practical applications.     

Metal-ion mediated separation of propylene from propane using PPO membranes

Tests with mixture of gases were carried out at room temperature (30±2°C) to determine selectivities and permeabilities of propylene and propane. The ideal selectivities of the membranes towards the olefin were also evaluated. Metal-incorporated poly (2,6-dimethyl-1,4-phenylene-oxide), (PPO) membrane was used for facilitating transport of the olefin through the membranes. The metals incorporated were Silver (Ag(I)), Palladium (Pd(II)), Ruthenium (Ru(III)) and Iridium (Ir(III)). PPO showed high ideal selectivities with respect to propylene. Among the metal-incorporated PPO membranes, significantly improved flux and selectivity was obtained especially for Ru(III) and Pd(II). Pd–PPO membranes exhibited two-fold improvement in propylene permeance with improved selectivity from 3.44 to 5.33. The membranes were characterised by Fourier Transform Infra Red spectroscopy (FTIR), Inductively Coupled Atomic Emission Spectroscopy (ICP-AES), Wide Angle X-ray-Diffraction (WAXD) and density measurements to understand the structural characteristics of the membrane responsible for the observed behaviour. From IR results the metals particularly Ru, Pd, Ag, Ir were found to interact with the polymer. The improved selectivity values of the metal incorporated polymers have been explained by a decrease in the effective distance (d_eff) between the adjacent intersegmental chains due to formation of metal–ion complex with the polymer matrix and hence a decrease in the free volume of the polymer upon metal incorporation. However, the significant improvements in the propylene permeabilities have been realised mainly due to the selective transport of propylene molecules mediated by the incorporation of selected metal ions.     

Support Modification of Supported Nickel Catalysts for Hydrogen Production by Auto-thermal Reforming of Ethanol

Recent progress on support modification of supported nickel catalysts for hydrogen production by auto-thermal reforming of ethanol was reported in this review. Nickel catalysts supported on various materials, including metal oxides and metal oxide-stabilized mesoporous zirconias, were prepared by an incipient wetness impregnation method for use in hydrogen production by auto-thermal reforming of ethanol. Various experimental measurements such as NH₃-TPD (temperature-programmed desorption) and TPR (temperature-programmed reduction) were carried out to elucidate the different catalytic performance of supported nickel catalysts. It was revealed that acid property of supporting materials served as one of the important factors determining the catalytic performance. Hydrogen yield over nickel catalysts supported on metal oxides showed a volcano-shaped curve with respect to acidity of the supports. Among the catalysts tested, Ni/ZrO₂ catalyst with an intermediate acidity exhibited a superior catalytic performance. It was also observed that reducibility of nickel catalysts supported on metal oxide-stabilized mesoporous zirconias played a key role in determining the catalytic performance in the auto-thermal reforming of ethanol for hydrogen production. Hydrogen yield over nickel catalysts supported on metal oxide-stabilized zirconias increased with increasing reducibility of the catalysts (with decreasing TPR peak temperature of the catalysts).     

Iron and cobalt salicylaldimine complexes as catalysts for epoxide and carbon dioxide coupling: effects of substituents on catalytic activity

The synthesis and characterization of substituted ONNO-donor salen-type Schiff base complexes of general formula [M^III(L)Cl] (L = Schiff base ligand, M = Fe, Co) is reported. The complexes have been applied as catalysts for the coupling of carbon dioxide and styrene oxide in the presence of tetrabutylammonium bromide as a co-catalyst. The reactions were carried out under relatively low-pressure and solvent-free conditions. The effects of the metal center, ligands, and various substituents on the peripheral sites of the ligand on the coupling reaction were investigated. The catalyst systems were found to be selective for the coupling of CO₂ and styrene oxide, resulting in cyclic styrene carbonate. The cobalt(III) complex with no substituents on the ligand showed higher activity (TON = 1297) than the corresponding iron(III) complex (TON = 814); however, the iron(III)-based catalysts bearing electron-withdrawing substituents on the salen ligands (NEt₃, TON = 1732) showed the highest catalytic activity under similar reaction conditions. The activity of one of the cobalt(III) complexes toward the coupling of 1-butene oxide, cyclohexene oxide and propylene oxide with CO₂ was evaluated, revealing a notable activity for the coupling of 1-butene oxide.     

Graphene‐Supported Ultrafine Metal Nanoparticles Encapsulated by Mesoporous Silica: Robust Catalysts for Oxidation and Reduction Reactions

Graphene nanosheet‐supported ultrafine metal nanoparticles encapsulated by thin mesoporous SiO₂ layers were prepared and used as robust catalysts with high catalytic activity and excellent high‐temperature stability. The catalysts can be recycled and reused in many gas‐ and solution‐phase reactions, and their high catalytic activity can be fully recovered by high‐temperature regeneration, should they be deactivated by feedstock poisoning. In addition to the large surface area provided by the graphene support, the enhanced catalytic performance is also attributed to the mesoporous SiO₂ layers, which not only stabilize the ultrafine metal nanoparticles, but also prevent the aggregation of the graphene nanosheets. The synthetic strategy can be extended to other metals, such as Pd and Ru, for preparing robust catalysts for various reactions.     

介孔氧化铝负载Ni-Co氧化物催化剂上丙烷氧化脱氢制丙烯

以非离子型三嵌段共聚物作为模板剂, 异丙醇铝为氧化铝的前驱物, 采用一锅法合成了一系列介孔氧化铝负载镍氧化物、钴氧化物以及镍-钴双金属氧化物催化剂, 并以介孔氧化铝为载体, 采用浸渍法制备了负载Ni-Co 氧化物催化剂. 采用N₂吸附-脱附、高分辨透射电镜(HRTEM)、X射线粉末衍射(XRD)、H₂程序升温还原(H₂-TPR)以及激光拉曼光谱(LRS)等技术对催化剂的结构与性质进行表征, 并考察了催化剂的丙烷氧化脱氢反应性能. 结果表明: 一锅法制备的各催化剂均有大的比表面积和规整的孔道结构, 且负载的金属氧化物高度分散; 而浸渍法制备的催化剂, 其载体的介孔结构被破坏并有Co₃O₄晶相生成. 在考察的催化剂中, 一锅法合成的介孔氧化铝负载Ni-Co 氧化物催化剂表现出最佳的丙烷氧化脱氢性能. 在450 °C、C₃H₈:O₂:N₂的摩尔比为1:1:4和空速(GHSV)为10000 mL·g^-1·h^-1条件下, 该催化剂上丙烯产率为10.3%, 远高于浸渍法制备的催化剂上所获得的丙烯产率(2.4%). 关联催化剂表征和反应结果, 讨论了催化剂结构与性能之间的关系.     

Alkylation of 2-methylquinoline with alcohols under additive-free conditions by Al2O3-supported Pt catalyst

Supported metal nanoparticle catalysts are studied for alkylation of 2-methylquinoline with benzyl alcohol under additive-free conditions in N₂ atmosphere. Among various metal-loaded Al₂O₃ catalysts and supported Pt catalysts, Pt metal nanocluster loaded-Al₂O₃ pre-reduced in H₂ at 500 °C shows highest yield (82%) of the product (2-phenethyl-quinoline). The catalyst is reusable, shows higher turnover number than a previous homogeneous catalyst, and shows good to moderate yield for alkylation of 2-methylquinoline with various alcohols. The reaction is driven by the borrowing-hydrogen pathway, in which aldehyde formed by dehydrogenation of alcohol undergoes aldol condensation with 2-methylquinoline to give the alkene intermediate which is finally hydrogenated by Pt-H species.     

Cellulose conversion to polyols on supported Ru catalysts in aqueous basic solution

It is of great significance and challenge to achieve direct conversion of cellulose to specific polyols, e.g., ethylene glycol and propylene glycol. For such selective conversion, a novel one-pot approach was studied by combination of alkaline hydrolysis and hydrogenation on supported Ru catalysts. A wide range of bases including solid bases, e.g., Ca(OH)₂ and La₂O₃, and phosphate buffers were examined in the cellulose reaction in water, and the cellulose conversions and polyol products depended largely on the basicity or pH values in the aqueous solutions. Ethylene glycol, 1,2-propanediol, and especially 1,2,5-pentanetriol were obtained with selectivities of 15%, 14% and 22%, respectively, at 38% cellulose conversion at pH 8 in phosphate buffer solution. These preliminary results provide potentials for efficient conversion of cellulose to targeted polyols by using the advantages of bases.     

Catalytic dehydrogenation of ethanol into acetaldehyde and isobutanol using mono- and multicomponent copper catalysts

The purpose of this work was to investigate biomass-derived ethanol dehydrogenation into acetaldehyde using several mono- and multicomponent (CuO, ZnO and Cr₂O₃)-containing catalysts supported on industrial size Al₂O₃ beads. The catalysts, prepared with either solution combustion or incipient wetness method, were characterized by using various physico-chemical methods, such as EDXA, SEM-EDXA, TEM, XRD, XPS, pyridine adsorption desorption FTIR, and ζ-potential measurements. The results revealed that the multicomponent catalysts exhibited superior activity compared to the metal oxide catalysts containing only one metal oxide. In addition, the most selective catalyst towards acetaldehyde formation, with 50% selectivity at 55% conversion of ethanol at 300 °C and WHSV 1 h^?1 was CuOCr₂O₃/Al₂O₃ prepared by using the solution combustion method, indicating that this inexpensive and rapid catalyst preparation method is promising for other applications.     

Ruthenium catalysts supported on TiO<Subscript>2</Subscript> prepared by sol–gel way for <Emphasis Type="Italic">p</Emphasis>-hydroxybenzoic acid wet air oxidation

The wet air oxidation of p-hydroxybenzoic acid, chosen as a model compound of olive mills wastewaters was carried out at 140 °C and 50 bar air over Ru catalysts supported on TiO₂ prepared by sol–gel method. These catalysts were characterized by means of N₂ adsorption–desorption, XRD and TEM. Optimization of the catalytic performances was obtained by studying some parameters such as the catalyst preparation method, the solvent evacuation way, the nature of the hydrolysis agent, the influence of the ruthenium salt used as the metal precursor (Ru(NO)(NO₃)₃ or Ru(acac)₃) and the catalyst pretreatment. The pre-calcination of the catalyst precursor at 300 °C under oxygen, before the reduction step under hydrogen, was detrimental to the activity. The results showed that the use of nitric acid as hydrolysis agent, drying under supercritical conditions and the use of Ru(NO)(NO₃)₃ leads to the more efficient catalyst with high TOC abatement.     

Products distribution of glycerol hydrogenolysis over supported co catalysts in a liquid phase

The products distribution of glycerol hydrogenolysis over supported Co catalysts was evaluated in a liquid phase system. The effects of support type, temperature, pressure and reaction time on the conversion of glycerol as well as yield of desired products were investigated. The preliminary results indicated that various added compounds were generated in the presence of supported Co catalysts. The type of support and the reaction temperature, pressure and time significantly affected either the glycerol conversion or the product yield. The acidity of catalyst played a more important role in the glycerol hydrogenolysis over supported Co catalysts than the specific surface and pore volume. Among the utilized supported Co catalysts, Co/γ-Al₂O₃ exhibited the highest acrolein yield of about 31.1% at 70.5% conversion at 200°C, 8 MPa H₂ pressure and 6 h reaction time.     

Light olefins and light oil production from catalytic pyrolysis of waste tire

This paper investigates the catalytic activity of MCM-41 synthesized via silatrane route and Ru/MCM-41 in waste tire pyrolysis. The experimental results showed that the presence of catalysts strongly influenced the yield and nature of products. Namely, the gas yield increased at the expense of liquid yield. In addition, a considerable high yield of light olefins, 4 times higher than non-catalytic pyrolysis, can be achieved for Ru/MCM-41 catalyst. Furthermore, the uses of catalysts produced much lighter oil and there was a drastic increase in the concentration of single ring aromatics in accordance to a reduction in polycyclic aromatic compounds in the derived oils. Ru/MCM-41 produced the lightest oil and the oil has the highest concentration of mono-aromatics. The high activity of catalysts, particularly Ru/MCM-41 was discussed in relation with the catalyst characterization results obtained from various techniques including TPD-NH₃, H₂-chemisorption, XRD, N₂-adsorption/desorption analysis, and TPO.     

负载型钌催化剂催化山梨醇氢解制乙二醇(英)

Supported Ru catalysts were prepared by wet impregnation to evaluate the role of different oxide supports（Al₂O₃,SiO₂,TiO₂,ZrO₂） in sorbitol hydrogenolysis to glycols.X-ray diffraction,transmission electron microscopy,hydrogen chemisorption,X-ray photoelectron spectroscopy,and NH3temperature-programmed desorption were used to characterize the catalysts,which were active in the hydrogenolysis of sorbitol.The support affected both the physicochemical properties and catalytic behavior of the supported Ru particles.The characterization results revealed that the Ru/Al₂O₃catalyst has a high surface acidity,partially oxidized Ru species on the surface,and a higher surface Ru/Al atomic ratio,which gave it the highest selectivity and yield to glycols.     

Selective CO Methanation over Ru Catalysts Supported on Nanostructured TiO2 with Different Crystalline Phases and Morphology

Nanostructured titanium dioxides were synthesized via various post-treatments of titanate nanofibers obtained from titanium precursors by hydrothermal reactions. The microstruc-tures of TiO₂ and supported Ru/TiO₂ catalysts were characterized with X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray analysis, and nitrogen adsorption isotherms. The phase structure, particle size, morphology, and specific surface area were de-termined. The supported Ru catalysts were applied for the selective methanation of CO in a hydrogen-rich stream. The results indicated that the Ru catalyst supported on rutile and TiO₂-B exhibited higher catalytic performance than the counterpart supported on anatase, which suggested the distinct interaction between Ru nanoparticles and TiO₂ resulting from different crystalline phases and morphology.