Effective hydrodeoxygenation bio-oil via natural zeolite supported transition metal oxide catalyst

Bio-oil from biomass pyrolysis is promising to be used as a sustainable biofuel and high-value-added chemical. However, the presence of high acid, water, and oxygenate causes corrosive properties, low higher heating value (HHV), and instability of the bio-oil component. Therefore, refining the bio-oil is essential to improve its quality. In this study, we introduced natural zeolite (HZ) impregnated with transition metal oxide (TMO) to refine the bio-oil using the hydrodeoxygenation method (HDO) at various catalyst ratios and temperatures. We find that ZnO/HZ 5% wt. shows the best catalytic performance, with the conversion of organic phase reaching ～ 50%. The refined bio-oil from Fe₂O₃, ZnO, and CuO has high-quality physicochemical properties with carbon, oxygen, water level, and HHV values are 37–52%, 40–53%, 8–27%, and 17–21 MJ/kg, respectively. This result represents a high catalytic performance for the hydrodeoxygenation process of bio-oil using natural zeolite-based transition metal oxide for better and low-cost biofuel production.     

有序多孔过渡金属氧化物及其负载贵金属催化剂对挥发性有机物氧化的催化性能

大部分的挥发性有机物(VOCs)污染环境,危害人身健康.目前,我国虽然已开展了治理 VOCs污染的工作,但还缺乏有效的、拥有自主知识产权的 VOCs治理技术,因此研发新型高效 VOCs处理技术迫在眉睫.催化氧化法是公认的最有效消除 VOCs的途径之一,而高性能催化剂的研发是实现该过程的关键.近年来,人们围绕消除 VOCs的高效且价廉的催化剂的研发开展了卓有成效的工作,许多过渡金属氧化物、混合或复合金属氧化物及其负载贵金属催化剂均被认为是有效的催化氧化材料.与体相材料相比,多孔材料具有发达的孔道结构和高的比表面积,一方面有利于反应物的扩散、吸附和脱附,因而具有更高的催化活性和选择性;另一方面有利于活性组分(如贵金属等)在多孔材料表面的高分散,抑制活性组分的烧结,因而具有更好的催化稳定性.本文简述了近年来多孔金属氧化物在环境污染物消除领域的研究进展,阐述了以有序介孔或大孔过渡金属氧化物、钙钛矿型氧化物和负载贵金属催化剂的制备及其对典型 VOCs(如苯系物、醇类、醛类及酮类等)氧化的催化性能,重点介绍了四类催化材料,包括有序介孔过渡金属氧化物或复合氧化物(Co3O4, MnO2, Fe2O3, Cr2O3和 LaFeO3等)催化剂,有序介孔金属氧化物负载贵金属(Au/Co3O4, Au/MnO2和 Pd/Co3O4等)催化剂,三维有序大孔过渡金属氧化物或复合氧化物(Fe2O3, LaMnO3, La0.6Sr0.4MnO3和 La2CuO4等)催化剂,以及三维有序大孔金属氧化物负载贵金属(Au/Co3O4, Au/LaCoO3, Au/La0.6Sr0.4MnO3和 AuPd/Co3O4等)催化剂的制备及其物化性质与对苯、甲苯、二甲苯、乙醇、丙酮、甲醛、甲烷或氯甲烷等 VOCs氧化的催化性能之间的相关性.借助二氧化硅或聚甲基丙烯酸甲酯微球等硬模板,采用纳米浇铸法可制备出二维或三维的有序单一或多级孔道结构的金属氧化物.研究表明,多孔金属氧化物的催化性能远优于其体相甚至纳米催化剂的.有序多孔材料的优异催化性能与其拥有大的比表面积、高的吸附氧物种浓度、优良的低温还原性、独特的孔道结构、活性组分的高分散以及贵金属与氧化物载体之间的强相互作用等有关.探明影响催化剂活性的因素有利于从原子水平上认识催化过程,为新型高效催化剂的设计与制备奠定基础.本文还指出了此类研究中存在的一些问题,例如利用硬模板法制备多孔材料的缺点是目标催化剂的收率低,硬模板浪费严重,大规模制备多孔催化剂势必增加制备成本,这些问题有待于妥善解决.与此同时,还展望了 VOCs消除技术的未来发展趋势,采用多种技术联用的方法有望最大程度地提高 VOCs的消除效率.     

Generation and characterization of supported films of transition metal and rare earth metal oxide catalysts

Summary The generation of catalytically relevant metal and/or metal oxide compounds supported on silica fibres is described. The systems investigated are Ni^o, Cu^o, Cu^o/ZnO, as well as perovskite-type La/Fe, La/Ni and La/Mn oxide phases. Ultrasound-aided generated vapours containing dissolved metal salt precursors are transferred onto preheated quartz fibres and transformed into the catalytically relevant phases by subsequent calcination. Analytical SEM and X-ray diffraction reveals the presence of differently crystalline, rough surfaces. The influence of the precursor salt and the conditions of calcination on the formation of the supported catalysts is discussed.     

Oxidative dehydrogenation of isobutane to isobutylene over supported transition metal oxide catalysts

Para-selectivity of ZSM-5 zeolites with similar bulk Si/Al ratio, but different particle size and surface Al concentration has been investigated in toluene disproportionation. Results showed that enhancedpara-selectivity is a consequence not only of the particle size but also of the external surface aluminium concentration in the particles.     

UV-Vis microspectroscopy: probing the initial stages of supported metal oxide catalyst preparation

A UV-vis microspectroscopy methodology for monitoring the speciation and macrodistribution of catalyst-precursor species inside catalyst-support bodies at the initial stages of catalyst preparation has been developed. The setup is based upon optical-fiber technology and allows spatially resolved analysis of bisected catalyst bodies. The potential of this tool is demonstrated by two pore-volume impregnation studies involving Ni2+ d-d transition bands and Cr6+ charge-transfer bands.     

Acid-base properties of supported vanadium oxide catalyst

Reduction of V₂O₅/Al₂O₃ and V₂O₅/silica-alumina produced Lewis acid sites which could strongly adsorb CO (heat of adsorption: 90 kJ/mol). Such strong acid sites were not formed in the cases of V₂O₅/SiO₂ and V₂O₅/MgO. V₂O₅ loaded on Al₂O₃ interacted with the basic sites of alumina but not with the acidic sites, while the V₂O₅ on silica-alumina interacted with the acidic sites of the silica-alumina and decreased its acidity.

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V₂O₅/Al₂O₃ V₂O₅/SiO₂–Al₂O₃ , CO ( 90 /). V₂O₅/SiO₂ V₂O₅/MgO . V₂O₅, Al₂O₃, , , V₂O₅ SiO₂–Al₂O₃ - .

     

Palladium oxide nanoparticles supported on graphene oxide: A convenient heterogeneous catalyst for reduction of various carbonyl compounds using triethylsilane

Palladium oxide nanoparticles supported on graphene oxide ‐ triethylsilane was found to be an effective reductive system for a broad range of reduction processes, including the reduction of various carbonyl compounds such as aromatic aldehydes to their corresponding alcohols or methyl arene compounds, aromatic ketones to their respective alcohols or saturated compounds, aromatic acyl chlorides to their reduced compounds. The desired products were obtained in good to excellent yields under mild conditions. The heterogeneous environmentally friendly catalyst can be easily separated from the reaction mixture through a simple filtration, facilitating purification of the prepared compounds.     

First-row transition metal compounds for aqueous metal ion batteries

In recent years,a series of aqueous metal ion batteries (AMIBs) has been developed to improve the safety and cost-efficiency of portable electronics and electri...     

Study of processes of interaction of aromatic compounds with the surface of manganese oxide catalyst

The scheme of the oxidative transformations of toluene, ethyl- and propylbenzene, and styrene during their chemisorption from a helium-oxygen mixture on the surface of a hydrated manganese dioxide under precatalysis conditions has been experimentally substantiated. These reactions lead to the formation of benzoate (toluene) or benzoate and formate (ethyl-, propylbenezene, styrene) structures on the surface.L. V. Pisarzhevskii Institute of Physical Chemistry. Ukrainian Academy of Sciences, Kiev. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 5, pp. 541–548, September–October, 1991. Original article submitted June 21, 1991.     

Catalytic activity of a zirconium(IV) oxide surface supported with transition metal ions

The kinetics of H₂O₂ decomposition have been investigated using ZrO₂ supported with transition metal ions including Cu^II, Ag^I, Hg^II, Co^II, Mn^II, Ni^II and Fe^III. At pH = 6.8, the reaction rate exhibits a first order dependence on the initial H₂O₂ concentration at low concentrations. The order of activity of the different catalysts is strongly dependent on the [H₂O₂]₀ used. The reaction proceed via the formation of the peroxo-intermediate which has an inhibiting effect on the reaction rate. The rate increases with increasing pH, and attains a limiting rate at higher pH's. A reaction mechanism is proposed involving liberation of HO₂ radicals from the peroxo-intermediate as the rate-determining step.     

Characterization of oxide supported metal carbonyl clusters

The chemisorption of [Ma₃(CO)_{1 2}] on silica (M = Ru and Os) and alumina (M = Os) has been studied by vibrational and X-ray absorption spectroscopies making close comparisons with model compounds. The results indicate that the first chemisorption species observed has the form [M₃H(CO)₁₀(O---O)]; the bridging hydride was observed directly for the silica systems as evidenced by the M-H-M bending vibration in the i.r. Also consistent with this structure are the EXAFS analysis of the Ru/SiOz material. This indicated an essentially equilateral ruthenium triangle and coordination to oxygen. The published low frequency Raman data on the Os/Al2Oa product was shown to match most closely with that of model compounds with a bidentate oxygen donor ligand (acac or O2CR). The tethered cluster [O_s3H₂(CO)₉(PPh₂C₂H₄SIL)] was found to be a relatively short lived species on a silica surface. Under ambient conditions it reacts further and the i.r., EXAFS and ³¹P NMR data of this species suggest that the two osmium atoms not coordinated to the tethering phosphine become involved with a bidentate site from the surface.     

Synthesis of arylaliphatic chlorosilanes by alkylation of aromatic compounds by alkenylchlorosilanes

Conclusions In combination with HCl or H₂O, EtAlCl₂ is an active catalyst for alkylation of aromatic compounds by alkenylchlorosilanes, and compounds of boron, titanium, and tin are inactive in this reaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1639–1641, July, 1985.     

The alkylation of aromatic compounds accompanying the demercuration of organomercury salts

Conclusions The possibility of using the demercuration of organomercury salts for alkylating certain aromatic hydrocarbons has been shown.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2083–2084, September, 1967.     

α-Polyfluroalkylbenzyl dichlorophosphates as alkylating agents in alkylation of aromatic compounds

On heating, α-polyfluoroalkylbenzyl dichlorophosphates alkylate mesitylene, durene, and naphthalene to give the corresponding aromatic compounds containing the α-polyfluoro-alkylbenzyl fragment as a substituent. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1866–1869, September, 1998.     

Gold-catalysed allylic alkylation of aromatic and heteroaromatic compounds with allylic alcohols

Friedel-Crafts allylic alkylation of a wide variety of aromatic and heteroaromatic compounds with allylic alcohols catalysed by AuCl(3) (5 mol%) under mild conditions at room temperature was accomplished in good to excellent yields (up to 99%) and regioselectivity.     

Conformational searching of transition metal compounds

To date, no conformational search of inorganic complexes has been reported that searches for all the conformations and configurations available to the complex. This is due to the various coordination geometries that transition metal ions can adopt and the difficulties in conducting conformational searches with systems that have connected ring systems, such as the ones formed when a metal ion binds a multidentate ligand. Using three test complexes {[Co(dien)₂]³⁺, [Co(dien)(dpt)]³⁺, and [Co(hexamethylcyclam)(Cl)} the ability of the random kick (Cartesian stochastic Monte Carlo search) method and the Monte Carlo dihedral and positional method to find all conformations and geometric isomers was tested (dien, diethylenetriamine; dpt, di(3-aminopropyl)amine; hexamethylcyclam: tet-a, meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane; tet-b, racemic-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). Both methods are significant improvements on the current method by which all possible isomers are entered graphically and minimized individually. The major difficulty that was encountered was how to differentiate between the large number of similar conformations found. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 1549–1558, 1999     

Superconductivity of some transition metal compounds

Single crystals of niobium carbonitride were made by zone melting growth methods and single crystals of γ-NbN and δ-NbN by zone annealing crystal growth. The crystals are nonstoichiometric in contrast to the niobium carbonitride or niobium nitride prepared in reaction with nitrogen gas and niobium-niobium carbide mixtures and niobium metal, respectively. The transition temperature for superconductivity (T_c) decreases with increasing deviation from stoichiometry, and a determination of T_c is a nondestructive determination of this deviation. An instrument using the Wheatstone bridge principle is described and T_c values are listed for some nonstoichiometric single crystals of niobium carbonitride and niobium nitride.     

Di- and poly-nuclear transition metal complexes as catalysts for the metal carbonyl substitution reaction. The role of supported metals and metal oxides as catalyst promoters

Various di- and poly-nuclear transition metal complexes have been investigated as catalysts for the metal carbonyl substitution reaction. The complexes [{(η⁵-C₅H₄R)Fe(CO)₂} ₂] (R = H, Me, CO₂Me, OMe, O(CH₂)₄OH) and [{(η⁵-C₅H₅)-Ru(CO)₂} ₂] are active catalysts for a range of substitution reactions including the probe reaction [Fe(CO)₄(CNBu^t)] + Bu^tNC → [Fe(CO)₃(CNBu^t)₂] + CO. [{(η⁵-C₅Me₅)Fe(CO)₂}₂] is catalytically active only on irradiation with visible light. For [{η⁵-C₅H₅)Fe(CO)₂}₂] and a range ofisocyanides RNC ( R = Bu^t, C₆H₅CH₂, 2,6-Me₂C₆H₃), catalyst modification by substitution with isocyanide is a major factor influencing the degree of the catalytic effects observed, e.g. [{(η⁵-C₅H₅)Fe(CO)(CNBu^t)}₂] is approximately 35 times as active as [(η⁵-C₅H₅)₂FE₂(CO)₃(CNBu^t)] for the [Fe(CO)₄(CNBu^t)] → [Fe(CO)₃(CNBu^t)₂] conversion. Mechanistic studies on this system suggest that the catalytic substitution step probably involves a rapid intermolecular attack of isonitrile, possibly on a labile catalyst-substrate radical intermediate such as {[Fe(CO)₄(CNR)][(η⁵-C₅H₅)Fe(CO)₂]}; or on a reactive radical cation such as [Fe(CO)₄(CNR)]⁺ generated via electron transfer between the substrate and the catalyst. Other transition metal complexes which also catalyze the substitution of CO by isocyanide in [Fe(CO)₄(CNR)] (and [M(CO)₆] (M = Cr, Mo, W), [Mn₂(CO)₁₀], [Re₂(CO)₁₀]) include [Ru₃(CO)₁₂], [H₄Ru₄(CO)₁₂], [M₄(CO)₁₂] (M = Co, Ir) and [Co₂(CO)₈]. These reactions conform to the general mechanistic patterns established for [{(η⁵-C₅H₅)Fe(CO)₂}₂], suggesting a similar mechanism. A range of materials, notably PtO₂, PdO and Pd/C, act as promoters for the homogeneous di- and poly-nuclear transition metal catalysts, and can even be used to induce activity in normally inactive dimer and cluster complexes e.g. [Os₃(CO)₁₂]. This promotion is attributed to at least three possible effects: the removal of catalyst inhibitors, a catalyzed substitution of the homogeneous catalyst partner, and a possible homogeneous-heterogeneous interaction which promotes the formation of catalytic intermediates.