重整重芳烃油烯烃选择性加氢催化剂的研究

研究了负载在Al₂O₃载体上的贵金属钯基催化剂对重整重芳烃油选择性加氢脱烯烃反应的性能。以重整残余重芳烃油为原料,分别对催化剂载体、贵金属负载量和助剂添加量进行考察。结果表明,700 ℃焙烧混有2%Ni的γ-Al₂O₃和负载0.2%的贵金属Pd综合效果最理想。催化剂稳定性结果表明,催化剂在500 h能保证产品溴指数在200 mg-Br·（100g^）-1以下,原料中萘环的损失在2%以下。     

Conversion of canola oil to various hydrocarbons over Pt/HZSM-5 bifunctional catalyst

Canola oil conversion was studied at atmospheric pressure over Pt/HZSM-5 catalyst (0.5 mass% Pt) in a fixed bed micro-reactor. The operating conditions were: temperature range of 400?500°C, weight hourly space velocity (WHSV) of 1.8 and 3.6 h^?1 and steam/oil ratio of 4. The objective was to optimize the amount of gasoline range hydrocarbons in the organic liquid product (OLP) and the selectivity towards olefins and isohydrocarbons in the gas product. The gas yields varied between 22–65 mass% and were higher in the presence of steam compared to the operation without steam. The olefin/paraffin mass ratio of C₂-C₄ hydrocarbon gases varied between 0.31–0.79. The isohydrocarbons/n-hydrocarbons ratio was higher with Pt/HZSM-5 (1.6–4.8) compared with pure HZSM-5 catalyst (0.2–1.0). The OLP yields with Pt/HZSM-5 (20–55 mass% of canola oil) were slightly lower compared to HZSM-5 (40–63 mass% of canola oil) under similar conditions. The major components of OLP were aliphatic and aromatic hydrocarbons. A scheme postulating the reaction pathways for the conversion of canola oil over Pt/HZSM-5 catalyst is also presented.     

Transformation of olefin over Ni/HZSM-5 catalyst

Olefins in the cracked naphtha can be transformed into aromatics and isoparaffin to reduce the olefin content as well as to improve the octane number. In this work, Ni/HZSM-5 bifunctional catalyst was prepared and was characterized by nitrogen adsorption, FT-IR analysis with adsorbed pyridine as well as by X-ray powder diffraction analysis. The activity of the catalyst was investigated with the transformation of 1-hexene. The experimental results show that the main reactions occurring over Ni/HZSM-5 at relatively low temperature are cracking and isomerization of 1-hexene, which results in the high concentration of olefin in the hydrotreated product. The double-bond isomerization of 1-hexene is dominant at low temperature (<220 °C) while the skeletal isomerization is elevated at high temperature, and the aromatization activity of the Ni/HZSM-5 catalyst is promoted by high temperature. The sulfided Ni/HZSM-5 catalyst shows higher aromatization activity than the reduced one and the zeolite supported Ni catalysts show comparatively better stability than that without metal components.     

Conjugated linoleic acid formation by hydrogenation/isomerisation of safflower oil over bifunctional structured catalyst Rh/SBA‐15

Directed isomerisation of safflower oil under very low hydrogen partial pressure of 7 psi over a novel bifunctional highly structured rhodium‐based catalyst (Rh/SBA‐15), having narrow pore size distribution ranging from 4 to 8 nm, and BET‐specific surface of ≈1,000 m² g^?1, was investigated as a new chemocatalytic approach for vegetable oil hardening and simultaneously producing health‐beneficial conjugated linoleic acids (CLA). Time course profiles of (cis‐9, trans‐11)‐; (cis‐10, trans‐12)‐; (trans‐10, cis‐12)‐; (cis,cis)‐ and (trans, trans)‐octadecadienoic isomers (CLAs) as well as the other fatty acids traditionally encountered during the hydrogenation of vegetable oils are presented and discussed under selected process conditions. Preliminary results show that it is possible to tailor characteristics of the hydrogenation catalyst in such way to confer its bi‐functional activity: hydrogenation and conjugation isomerisation. © 2011 Canadian Society for Chemical Engineering     

选择性催化加氢合成3,4-二氯苯胺的Pd/C催化剂研究

研究了Pd/C催化剂表面金属钯平均粒径对3,4-二氯硝基苯催化加氢反应选择性的影响，发现金属钯平均粒径越大，脱氯副反应越不明显，加氢选择性越高。采用浓硝酸预处理的活性炭负载钯催化剂虽然能够增大表面金属钯平均粒径，粒径分布却较宽，不利于加氢选择性的提高。使用饱和EDTA·2Na溶液预处理活性炭后，在钯负载量降低的情况下，可以达到活性炭载体表面金属钯大粒径、狭窄的分布，实现了在不添加脱氯抑制剂的情况下高选择性合成3,4-二氯苯胺。     

Ru/Na-H-ZSM-5双功能催化剂催化对苯二酚加氢

采用浸渍沉淀法制备了Ru/Na-H-ZSM-5系双功能催化剂,利用XRD、SEM、TEM、FT-IR及电泳仪等对催化剂结构、晶形外貌、孔道特点及表面电性进行测试,并在釜式反应器中进行催化性能评价。结果表明,Ru/Na-H-ZSM-5双功能催化剂用量0.5 g,反应压力3.0 MPa,反应温度130℃,反应时间3.0 h和Ru负载质量分数3.0%的条件下,对苯二酚转化率可达98.9%,目标产物1,4-环己二醇选择性达到85.2%。催化剂Ru/Na-H-ZSM-5用于对苯二酚加氢制备1,4-环己二醇反应活性组分Ru是关键所在,而分子筛结构以及电负性对于其反应有重要影响。     

Co-conversion of Ethane and Methanol into Higher Hydrocarbons over Ga/H-ZSM-5, Mo/H-ZSM-5 and Ga-Mo/H-ZSM-5

Ethane and methanol are converted simultaneously over Ga/H-ZSM-5, Mo/H-ZSM-5 and Ga-Mo/H-ZSM-5 to produce light olefins and aromatics. The presence of methanol in the reactant stream is intended to facilitate activation of ethane following literature reports on co-conversion of methane and methanol. However, the conversion of ethane actually decreases significantly when methanol is present. To gain insight into mechanistic details, ¹³C-labeled methanol is co-converted with unlabeled ethane. These isotopic labeling studies show that carbon atoms from ethane and methanol are mixed in the products and in the carbonaceous compounds deposited on the catalysts. This indicates that both reactants take part in the formation of the hydrocarbon pool, which is the origin of all products.     

AgCl/H-ZSM-5催化分解NO反应及失活机理

采用水热分散法制备了AgCl/H-ZSM-5催化剂，并对其催化分解NO的反应进行了研究。运用X-射线衍射（XRD）、固体魔角旋转核磁共振（MASNMR）和能量色散X-射线微区分析（EDAX）对Ag-Cl/H-ZSM-5催化剂进行表征，着重阐明AgCl/H-ZSM-5催化剂在NO分解反应过程中活性相、载体的结构变化与催化分解NO反应活性的关系。     

Highly selective palladium supported catalyst for hydrogenation of phenol in aqueous phase

Hydrogenation of phenol to cyclohexanone in aqueous phase, under mild conditions, has been carried out using palladium on different supports such as hydroxyapatite (HA), carbon (C), alumina (γ-Al₂O₃) and Al₂O₃-CWE synthesized with high surface area. High activity (100%) and selectivity (98%) to cyclohexanone was obtained using Pd/ Al₂O₃-CWE catalyst in 50 min under mild reaction conditions.     

A new catalyst for the selective hydrogenation of sunflower seed oil

A new Ni catalyst supported on sepiolite has been prepared by the precipitation/deposition method. Its activity and selectivity was tested in the hydrogenation reaction of sunflower seed oil. The variables studied were active phase concentration, reaction temperature and stirring speed. For contrasting purposes, a commercial catalyst designed for the same objective by Süd Chemie A.G. (Munich, Germany), G-53, was also tested under the same set of conditions. Selectivity to oleic acid with the new catalyst was appreciably better. The activation energies obtained with both catalyst were of the same order and within the range of those found in the literature for conventional nickel catalysts.     

Catalytic upgrading of fast pyrolysis oil over hzsm-5

The upgrading of bio-oil, obtained by fast pyrolysis of maple wood, was studied over HZSM-5 in a fixed bed micro-reactor operated at atmospheric pressure and in the temperature range 330-425°C. The objective of upgrading was to maximize the amount of organic distillate product with a high yield of aromatic hydrocarbons. A maximum organic distillate of 38 wt.% of bio-oil, which represented 28.6 wt.% of wood, was obtained at 370°C. The yield of aromatic hydrocarbons was 19.9 wt.% of wood. Above 400°C, nearly 50 wt.% of the bio-oil was converted to coke and char. The conversion of non-volatile components of the bio-oil (pitch) to volatiles was at a maximum of 68 wt. % at 370°C. However, when the bio-oil was co-processed with tetralin, the maximum conversion of non-volatiles increased to 86 wt.% at 410°C and the amounts of coke and char decreased. The yield of aromatic hydrocarbons also decreased to a maximum of 10.3 wt. % of wood. The role of tetralin was mainly as a diluent and not as a hydrogen donor solvent.     

Kinetics of selective hydrogenation of pyrolysis gasoline over an egg-shell catalyst

The kinetics of liquid-phase selective hydrogenation of pyrolysis gasoline over a commercial egg-shell catalyst was investigated in a stirred semi-batch reactor in the absence of external transport limitations. Experimental observations showed that competitive hydrogenation between monoolefins and diolefins was noticeable, and that the reaction rates of diolefins were much faster than those of monoolefins. A Langmuir–Hinshelwood-type reaction mechanism was proposed for the reaction system, and then a rigorous diffusion-reaction mathematical model was developed. For the egg-shell catalyst particle, the diffusion and reaction of species were described separately in two distinct regions, i.e., the outer active region, where both diffusion and reaction occurred, and the inner inertia region, where only diffusion happened. The kinetic and adsorption parameters were estimated from the diffusion-reaction model with the experimental data. The model was able to describe the experimental observations very well. The simulation results showed that significant concentration gradients existed inside the egg-shell catalyst, which revealed that the influence of the internal diffusion resistances on the reaction kinetics was considerable.     

Sugar hydrogenation over a Ru/C catalyst

BACKGROUND: In recent years, exploitation of renewable resources has gained considerable attention. In this respect, polyols derived from the hydrogenation of sugar molecules are versatile molecules with a variety of uses, such as low‐caloric sweeteners. The hydrogenation of D‐maltose, D‐galactose, L‐rhamnose and L‐arabinose was carried out on a finely dispersed Ru/activated carbon catalyst with the objective of studying the kinetics of the production of the corresponding polyols. The reactions were carried out in a stirred tank reactor at temperatures ranging from 90 to 130 °C and hydrogen pressures from 40 to 60 bar. RESULTS: Sugar conversions up to 100% were achieved. Some by‐product formation affecting the quality of the selectivity was also observed at elevated operating conditions. The catalyst was characterized by scanning electron microcopy (SEM), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectrometry (ICP‐OES) and nitrogen physisorption. Kinetic models based on the Langmuir Hinshelwood assumptions were proposed for the reactions and a nonlinear regression was performed to obtain the numerical values of the kinetic parameters. CONCLUSIONS: The kinetic models predicted well the sugar hydrogenation process and the kinetic parameters were established. The model can be used to predict the behaviour of batchwise operating slurry reactors. Copyright © 2011 Society of Chemical Industry     

分子筛在双功能催化剂中催化CO/CO2加氢研究进展

双功能催化剂可将CO/CO_2加氢直接合成低碳烯烃、芳烃和汽油等,具有工艺流程短、能耗低的优势。双功能催化剂由金属氧化物和分子筛两部分组成,分子筛特定的腔体结构、酸性质及与金属氧化物的结合方式等均可显著影响其催化性能。该文综述了近年来分子筛在双功能催化剂中用于CO/CO_2加氢反应的研究进展,简述了分子筛的类型、酸性质、形貌及颗粒尺寸、金属改性、分子筛与金属氧化物的结合方式等对双功能催化剂催化性能的影响规律,展望了双功能催化剂中分子筛的发展趋势。     

Metal cation–acidic proton bifunctional catalyst for methane activation: conversion of CH4 in the presence of ethylene over metal cations-loaded H-ZSM-5

It has been investigated that ¹³CH₄ reacts with ethylene over metal cations such as indium cations-loaded H-ZSM-5 to form singly ¹³C-labeled propylene (¹³C¹²C₂H₆) and hydrogen at 673 K. The heterolytic dissociation of C---H bond in methane presumably proceeds by the reaction of methane with metal cations for the formation of CH₃^δ+ and metal hydride species, thus allowing the reaction of CH₃^δ+ with ethylene to form propylene and acidic protons. Metal cations are regenerated by the reaction of silver-hydride species with acidic protons, and hydrogen is simultaneously formed. Thus, bifunctionality of metal cations and acidic protons is essential for the activation of methane.     

掺杂Co对CNTs负载Pt催化剂上肉桂醛选择性催化加氢性能的影响

研究了Co的掺杂对Pt/CNTs催化剂催化加氢肉桂醛反应性能的影响。结果发现, Co的掺杂对Pt/CNTs催化剂催化加氢活性起到明显促进作用, 并有利于C＝O基团的选择性加氢。Pt-0.17% Co/CNTs催化剂显示了较高的肉桂醇加氢选择性, 在反应条件为70℃、2 MPa和1.5 h时, 肉桂醛的加氢转化率达到97.1％,生成肉桂醇的选择性达到93.6％。同时, 初步研究了该催化剂上肉桂醛催化加氢反应动力学, 催化反应的活化能为26.5 kJ&#8226;mol^-1。     

Methane aromatization over Mo/H-ZSM-5: on the reaction pathway

Rates of benzene formation on Mo/HZSM-5, H-ZSM-5 and Mo/SiO₂ were measured with different reactants: methane, mixture of C₂H₄/H₂/N₂ and mixture of C₂H₂/H₂/N₂. Since the rate of benzene formation starting from C₂H₄/H₂/N₂ is higher on Mo/H-ZSM-5 compared to H-ZSM-5 it is concluded that the aromatization of methane on Mo/H-ZSM-5 is not going via ethylene which is aromatized over acid sites. Another reaction pathway is proposed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Highly enantioselective hydrogenation of α-Alkyl-β-arylpropenoic acids over cinchonidine-modified palladium catalyst

Enantioselective hydrogenation of (E)- α-alkyl-β-arylpropenoic acids was studied over the cinchonidine-modified Pd/C under the conditions optimized for (E)-α,β-diarylpropenoic acids. Enantiomeric excess (ee) of the product was increased by adjusting the α-alkyl group as a properly bulky isopropyl. The ee was as high as 80% when the β-group is phenyl, and reached 86% with p-anisyl group. Stereoselection of those substrates is similar to that of (E)-α,β-diarylpropenoic acids.     

Nb2O5 promoted Pd/AC catalyst for selective phenol hydrogenation to cyclohexanone

Phenol hydrogenation is a green route to prepare cyclohexanone, an intermediate for the production of nylon 66 and nylon 6. The development of high-performance catalysts still keeps a great challenge. Herein, the activated carbon (AC) was modified with an acidic material Nb₂O₅ to adjust the microstructure and surface properties of AC, and the influences of the calcination temperature and Nb₂O₅ content on the catalytic performance of the Pd/AC-Nb₂O₅ catalysts for the phenol hydrogenation to cyclohexanone were investigated. The Nb₂O₅ with proper content can be highly uniformly distributed on the AC surface, enhancing the acidity of the Pd/AC-Nb₂O₅ catalysts with comparable specific surface area and Pd dispersion, thereby improving the catalytic activity. The hybrid Pd/AC-10Nb₂O₅-500 catalyst exhibits the synergistic effect between the Pd nanoparticles and AC-10Nb₂O₅, which enhances the catalytic activity for the hydrogenation of phenol. Furthermore, the as-prepared Pd/AC-10Nb₂O₅-500 catalyst shows good reusability during 7 reaction cycles.     

Ru/C催化剂在苯选择加氢反应中的催化性能

采用沉积沉淀法制备了以活性炭(C)为载体的Ru催化剂,研究了Ru/C催化剂在苯选择加氢反应中的催化性能,并对Ru/C催化剂进行了表征.结果表明:Ru在催化剂中的分散性好,Ru/C催化剂具有较高的催化活性;适宜的反应条件为温度140℃,压力5.0 MPa,催化剂中Ru质量分数为4.0％,苯的转化率达40％以上,产物环己烯...