Chemioselectivity in the catalytic hydrogenation of cinnamaldehyde. Effect of metal particle morphology

The selectivity of platinum and rhodium catalysts for the hydrogenation of cinnamaldehyde into cinnamyl alcohol is much higher on large, facetted metal particles them on small (<3 nm) particles. This is attributed to a steric effect of the phenyl group which hampers the molecule to adsorb parallel to the flat metal surface thus favouring the adsorption and hydrogenation of the carbonyl group with respect to the C = C double bond.     

硝基苯液相催化加氢制苯胺催化剂研究进展

介绍了硝基苯液相催化加氢制苯胺的工艺过程,同时对该工艺所用催化剂体系(非贵金属类催化剂和贵金属类催化剂)进行了详述.非贵金属催化剂不仅存在对苯胺选择性差还存在对环境污染的问题;贵金属催化剂活性高,但成本也较高.开发催化活性高、稳定性好、寿命长、损耗低且环境友好型催化剂是硝基苯液相加氢催化剂发展的主研方向.     

载体对镍基催化剂顺酐液相加氢性能的影响

分别以ZrO₂、SiO₂与Al₂O₃为载体,采用等体积浸渍法制备了Ni质量分数为15%的催化剂,考察了其催化顺酐液相加氢性能,并利用BET、XRD、H₂-TPR以及TPO-MS等表征手段对催化剂进行了详细表征。结果表明,随载体不同各催化剂的加氢活性及选择性存在较大差异,Ni/Al₂O₃催化剂的C=C键加氢活性最高,但其几乎没有C=O加氢活性,催化顺酐加氢主产物为丁二酸酐。Ni/ZrO₂催化剂具有最高的C=O加氢活性,催化顺酐加氢主产物为γ-丁内酯,在反应温度为483 K,氢气压力为5 MPa的条件下反应8 h时,Ni/ZrO₂催化剂的γ-丁内酯选择性达79.20%。催化剂的套用实验表明,Ni/ZrO₂与Ni/SiO₂催化剂具有高的使用稳定性,Ni/Al₂O₃催化剂则在套用过程中快速失活。顺酐加氢至γ-丁内酯的中间产物--丁二酸酐与催化剂间的相互作用是影响催化剂加氢选择性及使用稳定性的主要原因。     

Ru催化加氢选择性脱除F-T合成水相中的含氧化合物

采用催化加氢技术脱除F-T合成水相中羧酸、醛、醇、酮、酯含氧化合物,考察了Ru/ZrO₂、Ru/TiO₂、Ru/SiO₂和Ru/Al₂O₃ 4种Ru催化剂的反应性能.相对于酸、醇,水中的醛、酮、酯更易被转化.其中Ru/ZrO₂和Ru/TiO₂具有良好的加氢脱羰活性,在200℃、9.8 MPa、3.0 h^-1空速下,酸、醛、醇、酮、酯均转化为C₁～C₆的烷烃,总转化率达92%.同条件下,虽然Ru/Al₂O₃对酸、醛、酮、酯的转化活性较高(>87%),但对醇的转化不到30%,具有选择性转化特点.H₂-TPR和NH₃-TPD结果表明,Ru/Al₂O₃催化剂的金属活性位与载体酸性位的协同作用有利于羧酸的加氢反应,能抑制醇的加氢脱羰活性;而金属-载体相互作用较弱和酸度较低的催化剂有利于羧酸、醇发生加氢脱羰反应.Ru/Al₂O₃催化剂运行500 h后失活,XRD、SEM和N₂-物理吸附表明,载体结构物相和织构性质的改变以及活性组分的流失是导致催化剂失活的主要因素.     

硝基苯催化加氢制对氨基苯酚工艺研究

介绍了硝基苯催化加氢制对氨基苯酚的工艺路线 ,并对其影响因素进行了探讨 ,得出最佳制备工艺 ,即在 85℃、硫酸含量 1 7%、体积比 6 .6、氢压 0 .2MPa、反应时间 2h等条件下 ,硝基苯转化率为81 .9% ,对氨基苯酚选择性 98.9%。     

插层阴离子对以类水滑石为前体Ni-Al2O3催化剂催化乙酰丙酸加氢性能的影响

分别以\mathrm{N}{\mathrm{O}}_{\mathrm{3}}^{-}以及\mathrm{C}{\mathrm{O}}_{\mathrm{3}}^{\mathrm{2}-}插层类水滑石为前体制备了Ni/Al摩尔比为3∶1的NiAl-N-R以及NiAl-C-R催化剂,并考察了其催化乙酰丙酸加氢性能。采用N₂-物理吸附、ICP-OES、TG/DTG、XRD、H₂-TPR/TPD、TEM、NH₃-TPD、in-situ Py-FTIR等表征手段对前体及催化剂进行了表征。研究结果表明,类水滑石插层阴离子对催化剂中活性金属-载体相互作用、活性金属分散度、表面酸性质以及催化乙酰丙酸加氢性能有重要影响。以\mathrm{C}{\mathrm{O}}_{\mathrm{3}}^{\mathrm{2}-}插层类水滑石为前体的催化剂表现出高的金属分散度、丰富的L酸酸性中心、高的CO加氢活性和高的循环使用稳定性。当以甲醇为溶剂、160℃、4 MPa氢气压力条件下反应1 h时,γ-戊内酯收率可达71.8%。     

Kinetics of catalytic transfer hydrogenation of soybean oil

The catalytic transfer hydrogenation of soybean oil was studied by using various concentrations of sodium formate solutions, an emulsifier and paladium on a carbon catalyst. Sodium formate concentration and addition of the emuldifier significantly affect the reaction rate because of their influence on the liquid/liquid interface. Under conditions in which diffusion effects are eliminated, all reactions carried out in diluted sodium formate solution obey first-order kinetics with respect to fatty acids. This allows control over the hydrogenation process of soybean oil, needed to obtain partially hydrogenated oil containing about 1% linolenic acid and a relatively high level of linoleic acid with no increase in the stearic acid concentration.     

硝基苯液相催化加氢制苯胺催化剂研究进展

介绍了苯胺生产中硝基苯液相催化加氢制苯胺工艺,着重介绍了液相加氢催化剂体系中的镍系催化剂和贵金属催化剂的研究进展。液相催化加氢多采用贵金属催化剂和高活性、制备工艺复杂的催化剂,生产成本较高,开发价廉、高效并能满足绿色化工要求的新型催化剂是今后工作的重点。     

硝基化物催化加氢及其催化剂开发进展

介绍了硝基化物催化加氢的优势及其催化剂的开发研究进展。硝基化物的催化加氢技术研究关键在于催化剂研究开发,主要催化剂的发展大都围绕自身的优势与不足展开,当前研究重点主要集中在进一步提高该体系催化剂的催化性能,特别是催化剂的选择性与稳定性,这也是今后进一步研究的主攻方向。     

二硫化钼催化加氢生物质油的研究

以微米二硫化钼(micro-MoS2)和纳米二硫化钼(nano-MoS2)为催化剂,在一定温度(250℃)和一定压力(2MPa)下,在间歇反应釜中进行生物质油的催化加氢实验,考察了不同粒径二硫化钼对生物质油催化加氢效果以及它们对产物性能的影响。同时,与生物质油催化加氢常用催化剂(Pd/C)进行对比,以期获得较佳的加氢催化剂。结果表明,在此温度条件下,nano-MoS2催化获得的精制油具有相对较高的H/C比值,由初始生物质原油的2.35增加到3.38;而Pd/C和micro-MoS2催化所得精制油具有相对较高的产率,分别为58.1%和55.7%。     

Effect of cations in solution on the oxidation of methanol on the surface of platinum electrode

The effect of metal cations in solution on the oxidation of methanol on the electrode surface of platinum is a neglected aspect to direct methanol fuel cell (DMFC). In this paper, a smooth platinum electrode absorbing metal cations as the working electrode was applied to investigate the methanol oxidation with the cyclic voltammetry (CV) in 1.0 mol L⁻¹ H₂SO₄. From the analysis of experiment, it is found that the cations, Li⁺, Ce⁴⁺, Mn²⁺, Ni²⁺, Cu²⁺, have some negative effect on the catalytic oxidation of methanol on the surface of platinum. The degree of the effect from different cations was analyzed.     

苯加氢催化剂Pd/MCM—41催化性能的研究

对负载型催化剂Pd/MCM—41进行了透射电镜及N2吸附表征。结果表明,金属Pd主要以纳米粒子的形式负载在分子筛表面,MCM—41的基本结构未被破坏。将Pd/MCM—41用于苯加氢反应,研究了反应温度和反应压力对催化活性的影响。结果表明,随着反应温度、反应压力的增加,苯的转化率得到有效提高。     

C3馏份选择加氢催化精馏工艺及其催化剂的研究

对C3馏份选择加氢催化剂及工艺条件进行了研究,试验结果表明,含有3.17%(物质的量的含量)丙炔和丙二烯的C3馏份经催化精馏加氢,塔顶C3馏份中的炔烃、二烯烃可脱至≤10μg/g,丙烯收率≥102%。经262h考核,催化剂仍保持良好的活性和选择性。     

新型碳三液相加氢催化剂工业侧线评价

以兰州石化24万吨乙烯车间裂解料为原料,模拟工业装置工况,LY-C3-A与对比催化剂1000 h活性和稳定性试验结果表明：在其它工艺相同条件下,LY-C3-A入口温度比对比剂低5～8℃、床层温升高2.3 ℃,LY-C3-A丙烯转化率优于对比剂4个百分点,且LY-C3-A催化剂丙烯选择性高于对比剂10个百分点。评价结果证明LY-C3-A综合性能优于对比剂且达到工业装置应用要求。     

催化氢化法制备醋酸甲脒的研究

采用以活性炭为载体负载Pd、In制备的催化剂，在醋酸存在条件下，将氰胺加氢合成醋酸甲脒。考察了催化剂组成（Pd-In/C）、反应温度、氰胺和醋酸的物质的量的比对反应速率的影响。结果表明，最佳反应条件为温度10 ℃，氰胺和醋酸的物质的量的比1∶1.1～1∶1.2。催化剂回收处理后可重复使用8次。     

Effect of support conductivity of catalytic powder on electrocatalytic hydrogenation of phenol

Metallic nanoaggregates deposited on non-conductive oxides powders as catalysts have shown good efficiency in electrocatalytic hydrogenation (ECH). In this process, the polarization of the metallic nanoaggregates is very important. This polarization can be improved when the electrode material is conductive. Thus, the goal of this work was to study the effect of the conduction of the supported material on the ECH process. Tin dioxide was chosen as oxide because it can be obtained in non-conductive or conductive form by doping with fluorine. Palladium supported catalysts powders were prepared by the sol–gel method. These electrocatalysts were characterized by XRD, SEM, TGA/DSC, FTIR and electrical conductivity. The effects of temperature and time of calcination were also investigated. Comparison of non-conductive and conductive catalysts for ECH of phenol shows that conductive F-doped SnO₂ increases the rate of electrohydrogenation.     

配位改性的Pt/C催化剂高选择性加氢合成3-氯-2-甲基苯胺

采用含氮有机化合物对炭载铂催化剂进行了配位改性,研究了改性剂对催化剂抑制脱氯性能以及催化加氢反应条件对芳胺选择性的影响。结果表明,经过改性的铂炭催化剂加氢反应转化率100%,脱氯产物小于0.1%,一次性得到高品质的医药级精细化工中间体。催化剂循环套用20次未见明显失活现象。     

Three-phase catalytic hydrogenation of xylose to xylitol — prolonging the catalyst activity by means of on-line ultrasonic treatment

A novel concept for improvement of the activity of recirculated Raney nickel catalyst by means of on-line ultrasonic irradiation was studied. Qualitatively, acoustic irradiation was clearly found to retard the catalyst deactivation in the three-phase hydrogenation of xylose to xylitol. Two different intensities of the ultrasonic field were utilized in the experiments. The hydrogenation kinetics was modeled with a semi-competitive reaction–adsorption model accounting for interstitital adsorption sites for hydrogen located between larger organic molecules.

The deactivation of the Raney nickel catalyst was found to diminish notably upon the use of on-line acoustic irradiation. Also, the selectivity of the system was found to be improved by the use of ultrasound in comparison to the case when no acoustic energy was dispatched to the system. The kinetic model used in the fitting of the data was able to explain the experimental concentrations fairly well.     

乙酸甲酯催化加氢制乙醇工艺

以煤基乙酸下游产品乙酸甲酯为原料, 在Cu-Zn-Al催化剂上加氢制取乙醇, 利用气相色谱仪对产品进行定性、定量分析。分别考察了反应温度、反应压力、乙酸甲酯液时空速、氢气与乙酸甲酯摩尔比等操作因素对乙酸甲酯转化率和目标产物乙醇选择性的影响。实验结果表明, 最佳工艺操作参数为:反应温度240℃, 反应压力8MPa, 乙酸甲酯液相体积空速1h^-1, 氢气与乙酸甲酯的摩尔比9:1。在最优工艺条件下, 乙酸甲酯的单程转化率为95.5%, 目的产物乙醇的选择性为94.6%。液体产品的平衡组成为:甲醇38.12%, 乙醇59.52%, 乙酸甲酯0.86%, 乙酸乙酯1.29%。数据表明:在乙酸甲酯加氢制乙醇反应过程中, Cu-Zn-Al催化剂对羰基加氢的活性较高, 对乙醇具有较高的选择性, 同时能够有效抑制主要副产物乙酸乙酯的生成。     

载体制备方法对Ni/TiO2催化剂顺酐液相加氢性能的影响

为了制备高活性和高选择性催化剂,实现顺酐下游加氢衍生物的定向合成,分别采用水热法、沉淀法和溶胶-凝胶法制备TiO2载体,并以浸渍法制备Ni质量分数为10%的Ni/TiO₂催化剂。采用N₂低温物理吸附、XRD、H₂-TPR及H₂-TPD等方法对催化剂进行表征,并评价催化剂的顺酐液相加氢性能。结果表明,以溶胶-凝胶法制备TiO₂为载体的催化剂具有最高的CC及CO加氢活性,在反应温度240 ℃和氢压5 MPa条件下,顺酐转化率为100%,γ-丁内酯选择性为52.2%,是相同反应条件下水热法TiO₂负载Ni催化剂的3.3倍和沉淀法TiO₂负载Ni催化剂的6.2倍。产生这一现象的原因与溶胶-凝胶法制备的TiO₂以锐钛矿和金红石混合晶相存在有关。