机械化学法制备的Al/Ce复合氧化物负载NiMo催化剂的加氢脱硫活性(英文)

将Al和/或Ce的硝酸盐与NH_4HCO_3球磨混合,采用机械化学法制备了Al_2O_3-CeO_2载体(其中Ce含量为1-10 wt%),再以杂多钼酸盐(NH_4)_4NiMo_6O_(24)为活性金属Ni和Mo的前驱体,通过浸渍法制备NiMo_6/Al_2O_3-CeO_2催化剂,并将其用于1-苯并噻吩(BT)的加氢脱硫(HDS)反应中.运用化学分析、X射线衍射、N_2吸附-脱附法、H_2程序升温还原、NH_3程序升温脱附和X射线光电子能谱对催化剂的物化性质进行了表征.结果表明,催化剂的酸性随着载体中Ce含量的增加而下降.Ce修饰的Al_2O_3载体表面的NiS/MoS原子比下降了2倍.NiMo_6/Al_2O_3催化剂表现出最高的HDS活性(以单位重量催化剂计),其酸性和表面MoO_xS_y物种的浓度(Mo~(5+)浓度)也最高;当催化剂中Ce含量逐渐增加到10 wt%以上时,其活性逐渐将为0.与浸渍法制得的参比催化剂相比,前驱体和催化剂组成相同的情况下,采用机械化学法制得的所有催化剂活性明显提高.     

氮掺杂介孔炭负载FeCu双金属催化剂及其CO加氢性能研究

利用氮掺杂介孔炭负载FeCu双金属,改变Fe/Cu组成,考察催化剂结构性质特征及其CO加氢反应性能。结果表明,Fe、Cu与N相互作用存在差异,Cu-N相互作用较强,并直接促进了Cu的分散。在较高的金属负载量（45.0%-50.0%,质量分数）下,Cu仍保持了与N一致的均匀分布特征,催化剂表面Fe/Cu组成也因为Fe、Cu分布特征差异而小于体相,这与常见Fe-Cu体系明显不同。在所用预处理条件（300℃的H₂气氛）下,Fe未被完全还原,H主要与Fe-O作用,以Fe-O-H形式存在,而Cu-N作用较强,金属Cu与H作用较弱,使得催化剂表面活性氢碳比降低,导致C₅₊选择性随Fe/Cu比值的减小逐渐增加。与此同时,载体向负载金属的电子偏移能力也随着Fe/Cu比值的减小逐渐增强,促使催化剂表面碱性随Cu含量的增加逐渐增强,最终导致C₅₊选择性、醇选择性进一步增加。     

Characteristics of hydrogen and carbon monoxide adsorption on supported rhodium-containing bimetallic catalysts

The methods of temperature-programmed desorption and microcalorimetry were used to determine the kinetic and thermodynamic characteristics of H₂ and CO adsorption on the surface of rhodium in bimetallic catalysts. The relationship between the chemical composition of the catalysts studied, electronic state of Rh, and parameters of the adsorption processes was determined.Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 31, No. 2, pp. 114–119, March–April, 1995.     

Influence of electronic state of rhodium in supported bimetallic catalysts on catalytic activity and selectivity in carbon monoxide hydrogenation reactions

Data on the mechanism and kinetics of the hydrogenation of carbon monoxide to saturated hydrocarbons and alcohols over supported bimetallic rhodium-containing catalysts are summarized and correlated. Rankings of specific catalytic activity and selectivity of Rh-M′/Al₂O₃ catalysts in relation to the chemical nature of M′, and hence in relation to the electronic state of the rhodium, are interpreted from a common point of view. On the basis of the interrelations that were found between the physicochemical and catalytic properties of these bimetallic systems, ground rules were formulated for selecting monotypical catalysts for the selective hydrogenation of carbon monoxide. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 4, pp. 199–218, July–August, 1997.     

Benzene hydrogenation on platinum-tin bimetallic catalysts

Various catalysts were prepared by impregnating a commercial alumina with solutions containing the complex dichlorobis(trichlorostannato)platinate (II). [Pt Cl₂ (SnCl₃)₂]^2–. After reduction, 1–20 fold variations in the catalytic activity in benzene hydrogenation were observed in direct proportion to the stability of the complex in the impregnating solution.

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, — - ( ()-(II) [PtCl₂(SnCl₃)₂]^–2. , 1–20 . .

     

Phosphorus modification of supported Pt catalysts for carbon monoxide hydrogenation

Modifying effect of phosphorus on the catalytic activity of supported Pt and Pt–Fe catalysts for CO hydrogenation has been studied. Phosphorus-containing compounds decrease significantly the methane yield with increasing yield of C₂–C₇ hydrocarbons.

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CO Pt- Pt–Fe-. , C₂–C₇.

     

Selective hydrogenation of citral over Au-based bimetallic catalysts in supercritical carbon dioxide

Selective hydrogenation of citral was investigated over Au-based bimetallic catalysts in the environmentally benign supercritical carbon dioxide (scCO₂) medium. The catalytic performances were different in citral hydrogenation when Pd or Ru was mixed (physically and chemically) with Au. Compared with the corresponding monometallic catalyst, the total conversion and the selectivity to citronellal (CAL) were significantly enhanced over TiO₂ supported Pd and Au bimetallic catalysts (physically and chemically mixed); however, the conversion and selectivity did not change when Ru was physically mixed with Au catalyst compared to the monometallic Ru/TiO₂, and the chemically mixed Ru-Au/TiO₂ catalyst did not show any activity. The effect of CO₂ pressure on the conversion of citral and product selectivity was significantly different over the Au/TiO₂, Pd-Au/TiO₂, and Pd/TiO₂ catalysts. It was assumed to be ascribed to the difference in the interactions between Au, Pd nanoparticles and CO₂ under different CO₂ pressures.     

Preparation of hydrogenation catalysts based on platinum nanoparticles supported on carbon nanomaterials

Hydrogenation catalysts as platinum nanoparticles supported on carbon nanomaterials (singleand multi-walled nanotubes, nanofibers, and fullerene black) have been obtained by modifying the platinum precursor with an organic base. A support pretreatment procedure for producing carboxyl groups on the nanotube and nanofiber surface is suggested.     

Combustion of methane over supported palladium-copper bimetallic catalysts

Monometallic and bimetallic catalysts based on palladium and copper deposited on a spinel carrier have been investigated in the catalytic combustion of methane. Great differences were found in catalytic activity, according to the sequence Pd/MgAl₂O₄>CuO–Pd/MgAl₂O₄>Pd–CuO/MgAl₂O₄>CuO/MgAl₂O₄. They were explained by changes in surface composition of the catalysts. In the case of bimetallic catalysts the metallic surface is preferentially enriched in copper, which acts as a diluting agent for the Pd atom ensembles. As a consequence, the adsorption of reactants is limited and the catalysts so obtained behave like copper slightly doped with palladium.     

NiFe双金属催化剂用于月桂酸甲酯加氢的研究

负载型Ni Fe/γ-Al₂O₃双金属催化剂的物理化学性质明显受还原温度的影响,进而影响月桂酸甲酯的加氢活性和产物选择性。金属Ni活性中心主要促进脱羰/脱羧(DOC)反应,Fe的加入能促进月桂酸甲酯发生加氢脱氧反应,促进C₁₂烷烃化合物生成。H₂-TPR、XRD、H₂-TPD和BET结果表明,高的还原温度有利于金属或合金活性中心形成,NiFe双金属催化剂的加氢活性取决于金属Ni、Fe和NiFe合金的含量;NiFe双金属催化剂吸附与活化H₂分子的能力明显受还原温度的影响。在研究的温度范围内,Ni活性中心具有优异的加氢和裂解性能,Fe物种的引入能有效抑制裂解性能。双金属催化剂的加氢活性顺序:NF420>NF360>NF450>NF300,在420℃下经H₂还原制得的NF420催化剂具有最佳的月桂酸甲酯加氢性能,在反应温度为380℃时,月桂酸甲酯加氢转化率和烷烃化合物选择性分别高达93.3%和90.0%。     

Mechanism and kinetics of the hydrogenation of CO to saturated hydrocarbons and alcohols on supported bimetallic catalysts containing rhodium

The mechanism of the simultaneous formation of methane, ethane, propane, methanol, ethanol, and propanol from carbon monoxide and hydrogen over supported bimetallic catalyst, Rh-M/Al₂O₃, has been established on the basis of kinetic and adsorption data. The experimental data are described quantitatively by kinetic and thermodynamic parameters calculated using the kinetic model.L. V. Pisarzhevskii Institute of Physical Chemistry, Ukraine National Academy of Sciences, Ukraine, 252039 Kiev, Nauki Prosp. 31. D. V. Sokol'skii Institute of Organic Catalysis and Electrochemistry, Kazakhstan National Academy of Sciences, Kazakhstan, 480110 Alma Ata, D. Kunaev Street, 142. Translated from Teoreticheskeskaya i Éksperimental'naya Khimiya, Vol. 32, No. 2, pp. 97–101, March–April, 1996. Original article submitted May 23, 1995.     

载Mo和Ni-Mo酚醛树脂基活性炭加氢催化转化羰基硫的研究

将水溶性酚醛树脂与金属盐溶液混合形成均相体系,依次通过减压蒸馏、固化、炭化、活化和预硫化处理制备负载金属硫化物的活性炭脱硫剂;研究其对羰基硫（COS）的加氢转化催化活性,考察了担载金属的种类、担载量、反应温度、反应时间和COS入口浓度等因素对催化反应的影响。研究结果表明,水溶性酚醛树脂是制备催化剂炭载体的理想前驱体;Ni Mo双组分催化剂对COS的加氢催化转化活性明显高于Mo单组分催化剂;在金属硫化物/活性炭催化剂上,COS的催化加氢过程属于内扩散控制,加氢反应气氛中一定浓度含硫组分的存在是抑制催化剂失硫及维持其催化活性的必要条件。     

Selective hydrogenation of nitrate to nitrite in water over Cu-Pd bimetallic clusters supported on active carbon

Hydrogenation of nitrate (200 ppm) in water with H₂ over Cu-Pd clusters supported on active carbon (AC) was investigated at 333 K using a gas–liquid co-current flow system. Two types of Cu-Pd bimetallic clusters, stabilized with either poly(vinylpyrrolidone) (PVP) or sodium citrate (SC), revealed that the catalysts possessed similar activity (per unit weight of Pd) and high selectivity toward nitrite when pH was 10.5 at the outlet of the reactor. The high selectivity toward nitrite on PVP-stabilized cluster/AC was minimally influenced by the atomic ratio of Cu/Pd (=0.5–4.0); activity was maximal at a ratio of 1:1. Increasing pH to 12.4 by addition of NaOH enhanced the selectivity toward nitrite to 93% over SC-stabilized Cu_0.63-Pd cluster/AC, but caused a decrease in the reaction rate. Over Cu_0.63-Pd cluster/AC, hydrogenation of nitrite as an intermediate occurred much more slowly than that of nitrate at pH 10.5, suggesting that high selectivity toward nitrite is attained by OH⁻ inhibiting adsorption of nitrite. XRD and STEM gave the size of the Cu_0.63-Pd cluster on AC as 4 nm; the structure of the cluster remained almost unchanged during the reaction. The activity and selectivity of the Cu_0.63-Pd cluster/AC was superior to those of the Cu_0.63-Pd cluster on oxides such as TiO₂, Al₂O₃, and ZrO₂. In addition, the Cu_0.63-Pd cluster/AC was more active and selective than conventionally prepared Cu_0.63-Pd/AC, indicating that the Cu-Pd cluster is an excellent precursor for selective catalysts in the hydrogenation of nitrate to nitrite.     

New high-selectivity hydrogenation catalysts prepared from bimetallic acetate complexes

The catalytic properties of new Pd-Zn/Al₂O₃ catalysts in selective acetylene hydrogenation in an acetylene-ethylene mixture at 30–120°C and atmospheric pressure are reported. The catalysts prepared from the bimetallic complex Pd-Zn(OOCMe)₄(OH₂) are much more selective than the catalysts prepared by simultaneously supporting the homonuclear complexes Pd₃(OOCMe)₆ and Zn(OOCMe)₂ · 2H₂O. It is demonstrated by diffuse reflectance IR spectroscopy of adsorbed CO that the heat treatment of the supported bimetallic complex at 250°C in flowing H₂ yields a Pd-Zn alloy on the surface. It is this alloy that ensures the high selectivity of the Pd-Zn/Al₂O₃ catalysts.     

Partial hydrogenation of benzene over platinum supported catalysts

Partial hydrogenation of benzene to cyclohexene has been studied on Pt/Nylon 66, Pt/MgO and Pt/TiO₂. An effect of the support on the selectivity to cyclohexene was observed, Pt/Nylon showing the highest selectivity, followed by Pt/MgO and Pt/TiO₂. An interaction of platinum with the more basic supports (Nylon, MgO) and a pretreatment under oxidizing conditions, results in a higher selectivity to cyclohexene.

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Pt/ 66, Pt/MgO PtTiO₂. , Pt/, Pt/MgO Pt/T,O₂. (, MgO) .

     

Dynamics of CO hydrogenation for bimetallic Co-Fe/Carrier catalysts

Bimetallic catalysts based a Co-Fe/carrier system are prepared via the consecutive and combined deposition of metals on Al₂O₃ and MgO · Al₂O₃. The dynamics of CO hydrogenation at 300°C is studied.     

Synthesis and characterization of niobium-promoted cobalt/iron catalysts supported on carbon nanotubes for the hydrogenation of carbon monoxide

Bimetallic Co /Fe catalysts supported on carbon nanotubes( CNTs) were prepared,and niobium( Nb) was added as promoter to the 70 Co ∶30Fe /CNT catalyst. The physicochemical properties of the catalysts were characterized,and the catalytic performances were analyzed at the same operation conditions( H_2 ∶CO( volume ratio) = 2 ∶1,p = 1 MPa,and t = 260 ℃) in a tubular fixed-bed microreactor system. The addition of Nb to the bimetallic catalyst decreases the average size of the oxide nanoparticles and improves the reducibility of the bimetallic catalyst. Evaluation of the catalyst performance in a Fischer-Tropsch reaction shows that the catalyst results in high selectivity to methane,and the selectivity to C_(5+) increased slightly in the bimetallic catalyst unlike that in the monometallic catalysts. The addition of 1% Nb to the bimetallic catalyst increases CO conversion and selectivity to C_(5+). Meanwhile,a decrease in methane selectivity is observed.     

Synergic effect of palladium-based bimetallic catalysts for the hydrogenation of nitroaromatics

Bimetallic catalysts, PdCl₂-MX_n and PdCl₂(PhCN)₂-Mx_n (MX_n=FeCl₃, Fe(acac)₃, Co(OAc)₂, CoCl₂, Co(acac)₂, NiCl₂, Ni(OAc)₂, RuCl₃, Cu(OAc)₂, CuCl₂), exhibit remarkable synergic effect which can obviously increase the activity of the monometallic Pd catalyst for the hydrogenation of nitroaromatics, whereas MX_n alone is not catalytically active under the same reaction conditions.