The catalytic dehydrogenation of cyclohexane and methylcyclohexane over nickel loaded Y zeolites

The dehydrogenation of cyclohexane to benzene and of methylcyclohexane to toluene was investigated over a range of nickel Y zeolites, varying the nickel content and the nature of the alkali metal co-cation (Li⁺, Na⁺, K⁺, Rb⁺ or Cs⁺). The overall reaction is viewed as occuring via a series of consecutive dehydrogenation steps. Catalytic activity is correlated with the reaction time, the reaction temperature, the level of Ni²⁺ exchange and the effects of pyridine adsorption. The level of dehydrogenation is strongly dependent on the mass of supported nickel metal and the surface Bronsted acidity. Catalyst deactivation results from the deposition of coke on the catalyst surface which is promoted with increasing zeolite acidity.     

Studies of the effects of the modification conditions on the hydrogenation rate for the enantio-differentiating hydrogenation of methyl acetoacetate over a tartaric acid–NaBr-modified nickel catalyst

The effects of the modification conditions on the hydrogenation rate and the enantio-differentiating ability (e.d.a.) for the enantio-differentiating hydrogenation of methyl acetoacetate were studied over an (R, R)-tartaric acid–NaBr-in-situ-modified nickel catalyst. It was revealed that a tartaric acid modification increased the hydrogenation rate irrespective of the presence of the auxiliary modifier, NaBr. In the presence of the tartaric acid, NaBr would have two roles, i.e., Na⁺ activates the enantio-differentiating sites through the interaction with tartaric acid, and Br⁻ deactivates both the enantio-differentiating sites and non-enantio-differentiating sites. The e.d.a. values and the hydrogenation rate would be determined by the combination of these effects of Na⁺ and Br⁻.     

Effect of Mg2+, Li+, Na+ and K+ on the Electrocrystallization of Nickel from Aqueous Sulfate solutions containing Boric Acid

The effects of metal ions such as Mg²⁺, Li⁺, Na⁺ and K⁺ on the cathodic current efficiency, deposit morphology, crystallographic orientation and polarization behaviour during nickel deposition on stainless steel from aqueous sulfate solutions containing boric acid were investigated. There was virtually no change in current efficiency in presence of these metal ions, but changes were observed in the deposit morphologies and crystal orientations even though all the deposits looked bright, smooth and coherent. Changes were also observed in the polarization behaviour during nickel electrocrystallization in presence and absence of boric acid. An attempt has been made to correlate the effect of these metal ions on various parameters studied.     

Liquid‐Phase Hydrogenation of m‐phenoxybenzaldehyde to m‐phenoxybenzylalcohol Using Raney Nickel Catalyst: Reaction Kinetics

Kinetics of the liquid‐phase catalytic hydrogenation of m‐phenoxybenzaldehyde to m‐phenoxybenzyl alcohol have been investigated over the Raney nickel catalyst. Effects of hydrogen partial pressure (500‐2000 kPa), catalyst loading (1.6‐6.4 g.L^?1), m‐phenoxybenzaldehyde concentration (0.2‐0.8 mol.L^?1) and temperature (333‐363 K) on the progress of the reaction were studied. The speed of stirring > 15 rps has no effect on the initial rate of reaction. Effects of various catalysts and solvents on the hydrogenation of m‐phenoxybenzaldehyde have been investigated. The reaction was found to be first order with respect to the hydrogen partial pressure, catalyst loading and m‐phenoxybenzaldehyde concentration. Several Langmuir‐Hinshelwood type models were considered and the experimental data fitted to the model involving surface reaction, between dissociatively adsorbed hydrogen and molecularly adsorbed m‐phenoxybenzaldehyde.     

Study on the preparation and the catalytic performance of Ni-modified shock-wave synthesized diamond blends and nanodispersed diamond

The possibility to use shock-wave synthesized diamond blend and ultradispersed diamond powder isolated from it as supports for catalytically active nickel metal phase has been studied. The influence of the pre-treatment conditions for the metal precursor decomposition and generation of Ni⁰ upon reduction have been investigated. The present findings reveal that the state of the supported nickel is predetermined by the conditions of the catalysts preparation. The reaction test showed that the graphite containing diamond blend is not appropriate as a support. In contrast, the ultradisperssed diamond powder appears very promising for disposition of metallic nickel active in the catalytic hydrogenation of toluene.     

Raney Ni催化剂的制备及应用研究

Raney-Ni催化剂是一种十分重要的骨架型催化剂,由于其具有的高活性及高选择性,被广泛应用于有机反应。本文简述了Raney Ni催化剂的制备方法,阐述了铝镍合金晶体结构、第三金属、残余铝、活化条件和催化剂粒度对活性的影响,并对Raney Ni催化剂在氢化反应、脱硫、脱卤反应、硝基加氢反应、氨解反应等方面的应用作了概括说明。     

Drastic ligand electronic effect on anilido-imino nickel catalysts toward ethylene polymerization

A novel nitro-anilido-imino nickel complex (Ar¹NCHC₆H₃(-5-NO₂)NAr²)NiBr (Ar¹ = Ar² = 2,6-dimethylphenyl) was designed, synthesized, and characterized to investigate ligand electronic effect on late transition metal olefin polymerization catalysts. As a catalyst for ethylene polymerization, neutral anilido-imino nickel complex with an electron-withdrawing nitro group showed good activity (442.1 kg (mol Ni h)⁻¹) with MAO as cocatalyst. The catalytic activity and molecular weight of the obtained products were significantly affected by electronic effect of the anilido-imine ligand. Theoretical calculations suggested that ligand electronic effect led to different charge distribution on the nickel metal atom, and the catalytic activity predominantly increased with an increase in electrophilicity of the nickel metal center.     

纳米镍与骨架镍催化性能比较

引　言骨架镍是一种典型的加氢催化剂 .骨架镍催化剂具有价格便宜等优点 ,但是研究发现骨架镍的催化选择性低[1] ,而且也比较容易失活[2 ] .同骨架镍催化剂相比 ,纳米镍具有一些优良的特性[1] .直接比较纳米镍与骨架镍的催化稳定性还未见报道 .为此 ,本文以对硝基苯酚催化加氢为模型反应来比较纳米镍与骨架镍的催化活性与稳定性 ,并通过一系列的表征技术来分析使用前后催化剂物理性能的变化 ,试图对两种催化剂催化性能的差异做出解释 ,同时也希望为工业上使用纳米镍代替骨架镍催化剂提供一些依据 .1　实验部分1 1　主要原料及试剂主要原料 :…     

Highly uniform Ni particles with phosphorus and adjacent defects catalyze 1,5-dinitronaphthalene hydrogenation with excellent catalytic performance

This work proposes a modified activated carbon support, with defects and heteroatoms (N,P-ACs) by nitrogen and phosphorus doping to load non-noble nickel to catalyze aromatic compound hydrogenation. The Ni/N,P-ACs-900 (prepared at 900 °C) showed promising catalytic activity in liquid-phase 1,5-dinitronaphthalene hydrogenation with a 1,5-diaminonaphthalene yield of 95.8% under the mild condition of 100 °C, which is comparable to the commercial Pd/C catalyst. The nitrogen species were burned off at 900 °C, causing more defects for nickel metal loading, facilitating the interaction between the supports and the nickel metal, and resulting in highly dispersed metal particles. The computational study of the nickel binding energy has been conducted using density functional theory. It exhibits that the defects formed by heteroatom doping are beneficial to nickel anchoring and deposition to form highly uniform nickel particles. The phosphorus species in combination with the defects are suitable for H₂ adsorption and dissociation. These results reveal that the heteroatomic doping on the active carbon shows significant effects in the hydrogenation of the liquid-phase aromatic compounds. These findings could provide a promising route for the rational design of aromatic compound hydrogenation catalysts to significantly decrease the cost by instead using noble metal catalysts in the industry.     

新型固定床Raney镍(Ⅰ)成型合金的组成与焙烧条件

以拟薄水铝石为黏结剂,将镍铝合金粉末成型,经高温焙烧、碱液浸取活化,制备出可应用于不饱和化合物固定床加氢的新型颗粒状Raney镍催化剂.采用TG-DTA、XRD、BET、SEM等方法和苯加氢模型反应,研究了成型合金焙烧条件以及拟薄水铝石加入量对催化剂性质与加氢活性的影响.实验结果表明,拟薄水铝石加入量以20%左右为宜;成型合金在860 ℃焙烧1～2 h,可获得适当的α-Al₂O₃生成量、较高的机械强度和较高的苯加氢活性.SEM和BET分析结果表明催化剂具有丰富的孔道结构.     

Preparation of Ni/SiO2 catalyst in ionic liquids for hydrogenation

A series of silica supported nickel catalysts were prepared from nickel nitrate and tetraethyl orthosilicate by the sol-gel method with the imidazolium type ionic liquids as solvents. The catalysts were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Their catalytic performances for the selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde were investigated. The results show that the Ni/SiO₂ catalyst prepared with 1-(2-hydroxyethyl)-3-methylimidazole tetrafluoroborate ionic liquid as solvent exhibits the highest catalytic activity for the reaction. Under the optimal conditions of catalyst dosage (based on the mass of cinnamaldehyde used) 10%, reaction pressure 2 MPa, temperature 373 K and reaction time 2 h, the conversion of cinnamaldehyde and the selectivity to hydrocinnamaldehyde can reach 97.6% and 98.8%, respectively. __________ Translated from Petrochemical Technology, 2007, 36(1): 9–14 [译自:石油化工]     

Ni catalysts supported on activated carbon from petcoke and their activity for toluene hydrogenation

Petroleum coke (petcoke) is an abundant resource that can potentially be converted to catalyst support materials through activation to increase the surface area and reduce the sulphur content. In this work, potassium hydroxide (KOH) catalysed activation was employed with petcoke to produce activated carbons, which were characterised with nitrogen physisorption, X‐ray diffraction, scanning electron microscopy and temperature‐programmed reduction. With activation temperatures between 500 and 800°C, the surface area increased from 4 m²/g to between 200 and 2400 m²/g while the sulphur content was reduced from 6.6 wt% to between 1 and 0.2 wt%. Nickel catalysts (nominally 5 wt%) were prepared on the activated carbon supports using wet impregnation. The activities of these catalysts were measured for toluene hydrogenation in a plug‐flow reactor with a toluene liquid hourly space velocity of 2.4/h, a pressure of 1.38 MPa, and a H₂/toluene mole ratio of 90. The catalytic activity varied between zero for nickel supported on petcoke to 98% conversion, with essentially 100% to methylcyclohexane for nickel supported on carbon activated at 750°C. Thus, activated carbon from petcoke was a suitable support for Ni‐based catalysts when used for toluene hydrogenation as a model reaction. © 2011 Canadian Society for Chemical Engineering     

Studies of the effect of pivalic acid on the hydrogenation rate and the enantio-differentiating ability for the hydrogenation of 2-octanone over a tartaric acid-NaBr-modified nickel catalyst

The effects of the addition of pivalic acid to the reaction media on the hydrogenation rate and the enantio-differentiating ability (e.d.a.) for the hydrogenation of 2-octanone were studied over an (R,R)-tartaric acid-NaBr-in-situ-modified nickel catalyst. It was revealed that the modification with both tartaric acid and NaBr was necessary for increasing the e.d.a. by the addition of pivalic acid to the reaction media. The role of pivalic acid in the enantio-differentiating hydrogenation of 2-octanone was different from that of acetic acid in the hydrogenation of methyl acetoacetate.     

Direct and transfer hydrogenation of furfural over MOF-derived Pd-Cu@C catalysts

Owing to the self-reducing ability of palladium acetate in solutions, an ethanol solution containing Pd⁰ particles was prepared and coated in-situ into copper metal–organic framework (Cu-MOF), forming Pd@Cu-MOF in a coated structure. The Pd@Cu-MOF was reduced under N₂ or H₂ to form carbon-coated Pd-Cu@C. The pyrolysis and carbonization of Cu-MOF and the reduction of Cu²⁺ were studied. The Cu-MOF under either N₂ or H₂ was pyrolyzed and carbonized, but the Cu²⁺ reduction mechanisms were different. The high-temperature carbothermic reduction of Cu²⁺ under N₂ produced Cu⁰, but during low-temperature reduction under H₂, the reducing H₂ reduced Cu²⁺ to Cu⁰. Furfural hydrogenation experiments showed that compared with H₂, the Pd-Cu@C prepared under N₂ reduction displayed higher furfural hydrogenation activity. The catalytic activity of Pd-Cu@C prepared from in-situ Pd⁰ coating was higher than the Pd/Cu@C prepared from the impregnation method. With i-propanol as the solvent, the catalytic hydrogenation of furfural under H₂ consisted of direct catalytic hydrogenation with molecular hydrogen as the hydrogen source and catalytic transfer hydrogenation with i-propanol as the hydrogen donor. The catalytic activity of direct catalytic hydrogenation is higher than the catalytic transfer hydrogenation.     

The reaction of CO2 with CH4 to synthesize H2 and CO over nickel-loaded Y-zeolites

Nickel metal introduced into Y-zeolite exhibited a high catalytic activity in the dehydro-genation of methane and in the hydrogenation of carbon dioxide with methane to obtain hydrogen and CO at about 850 K. The activity strongly depended on the nickel amount in NaY, and the catalytic properties were influenced by the kind of cations in the Y-zeolite. The higher CO₂ conversion was obtained over Ni supported on non-acidic zeolites.     

Hydrodesulfurization and hydrogenation of aromatic compounds catalyzed by Ni-Mo/γ-Al2O3: effects of nickel sulfide and vanadium sulfide deposits

A standard Ni-Mo/-Al₂O₃ catalyst containing 4 wt% Ni was modified by addition of nickel (2 wt%) and, alternatively, of vanadium (4 wt%) by contacting with a solution of the respective metal naphthenate. The catalysts were sulfided and tested in a batch reactor at 350°C and 165 bar for hydrogenation of naphthalene and for hydroprocessing of dibenzothiophene. Reaction networks were determined for each reactant, and the dependence of the pseudo firs-torder rate constants on the amount of nickel and of vanadium in the catalyst was used to determine the effects of nickel sulfide and of vanadium sulfide deposits on catalyst performance. For example, the nickel sulfide deposits only slightly affected the rate constants for hydrogenation in either network, but the vanadium sulfide deposits led to a decrease of at most 50% in the rate constants for hydrogenation reactions in the naphthalene network and to a doubling of the rate constants for hydrogenation reactions in the dibenzothiophene network. The nickel sulfide deposits led to almost no change in the rate constant for hydrogenolysis of dibenzothiophene (to give biphenyl), but the vanadium sulfide deposits led to a threefold decrease in the rate constant for this reaction. The nickel sulfide deposits have little activity for reactions giving lower-molecular-weight (cracking) products, but the vanadium sulfide deposits have a relatively high activity for cracking, which suggests that they are acidic. The effects of the deposits are complex, as they both block catalytic sites and form new ones. The results indicate a need for representing the nickel and sulfide deposits separately in process models for heavy oil hydroprocessing.     

Promoting action of water on slurry phase hydrogenation of p-nitrotoluene on raney nickel

Enhancement in the reaction rate of hydrogenation of p-nitrotoluene on Raney nickel in a three-phase slurry reactor due to the presence of water in the reaction mixture has been observed. The promoting action was found to be dependent on the initial concentration of water, the reaction rate passed through a maximum when the initial water concentration varied from 0.0 to 10.85 (mmol cm^-3). A two to three fold increase in the reaction rate dependent on the temperature has been observed at the optimum water concentration. However, at very high concentrations (above 8.0 mmol cm-³) water inhibited the hydrogenation. The reaction is not influenced significantly by the presence of p-toluidine.     

Ni(ll) biosorption by Rhizopus arrhizus Env 3: the study of important parameters in biomass biosorption

BACKGROUND: The removal of toxic metals from wastewaters by biosorption, based on the metal‐binding capacities of various biological materials, has attracted much interest. However, the success of this approach depends on economic feasibility, which can be obtained by optimisation of the environmental conditions. In this study, Ni(II) biosorption experiments were carried out using a preformed biomass of Rhizopus arrhizus. A pure culture of previously isolated R. arrhizus Env 3 was used for maximum biosorption of nickel metal from nickel‐electroplating industrial effluent. RESULTS: Various environmental factors such as nickel concentration, pH, temperature, mycelial pellet weight, pretreatment of fungal biomass, dead and living fungal biomass and time course of biosorption by R. arrhizus Env 3 were optimised for maximum removal of nickel from the effluent. The maximum nickel removal rate of 618.5 mg g^?1 was observed with living biomass at pH 8, temperature 35 °C, nickel concentration 500 mg L^?1, pellet size 3 g wet weight and shaker velocity 150 rpm. Maximum nickel biosorption was obtained after 72 h. CONCLUSION: Statistical analysis of different factors such as temperature, pH, mycelial pellet size, concentration of nickel in effluent and residual nickel level showed that all these factors had significant effects on the biosorption of nickel metal by R. arrhizus Env 3 from nickel‐electroplating industrial effluent. Copyright © 2008 Society of Chemical Industry     

催化加氢制备对苯二胺工艺的研究

介绍催化加氢制备对苯二胺的方法,以非晶态镍作为加氢催化剂、甲醇作为溶剂,优化后反应温度为100℃、反应压力为0.8 MPa,加氢转化率达99.6%,产品质量分数为99.5%,使用锌粉作为抗氧剂,产品密闭存放30天不变色。     

盐酸吡格列酮的合成工艺研究

本文以如下合成路线为基础:羟基苯甲醛与2,4-噻唑烷二酮缩合后,经催化氢化,再与2-羟乙基-5-乙基吡啶磺酸酯对接,成盐得到盐酸吡格列酮,然后考察了催化氢化步骤中催化剂种类、用量、溶剂种类、反应温度和反应时间对反应收率的影响,从而找到了最适宜的催化氢化的反应工艺参数:催化剂为雷尼镍,催化剂用量为雷尼镍与中间体(5)的质量比为80%,溶剂为甲醇,反应温度为105℃,反应时间5h。找到了一个既能提高反应的收率,而且经济适用,适合工业化大生产的反应工艺。