镍基催化加氢合成氨基己腈

以Ni/K_2O-La_2O_3-Al_2O_3为催化剂,采用固定床反应器,系统地考察了反应温度、氢气空速、己二腈液时空速和进料速率等对己二腈选择加氢生成6-氨基己腈的影响。结果表明,随着反应温度的升高,己二腈加氢转化率先增加后降低,6-氨基己腈选择性逐步下降;其中提高氢气空速、降低己二腈液时空速和进料速率(氢腈物质的量之比不变),均有利于提高己二腈转化率,但6-氨基己腈选择性下降。以乙醇为溶剂,在常压,温度180℃,氢气空速3 600 h~(-1),己二腈液时空速0.24 h~(-1),己二腈的乙醇溶液流速5 mL/h(氢腈物质的量之比为86)的条件下,催化性能较好,反应40 h后趋于稳定,己二腈的转化率基本维持在50%～55%,6-氨基己腈的选择性为80%左右。     

己二腈选择加氢镍基催化剂的失活和再生

以乙醇为溶剂,在常压、温度180℃、己二腈液时空速0.24 h-1、氢气空速1 700 h-1和进料速率5 mL/h(氢腈物质量比约为41)反应条件下,采用固定床反应器考察了不同助剂改性的负载型镍基催化剂上己二腈选择加氢制备6-氨基己腈的反应性能。结果表明,适量的K2O和La2O3助剂的加入,不仅提高了镍基催化剂对6-氨基己腈选择性,而且提高了加氢反应的稳定性。热失重(TG),能量分析光谱(EDX)和X射线衍射(XRD)分析表明,催化剂表面含C和N有机物种的沉积是催化剂失活的主要原因,Ni晶粒的长大也是失活原因之一。采用器内直接H2还原、器外乙醇洗涤和二次焙烧还原对失活催化剂进行再生,可在一定程度上恢复催化剂的活性以及对6-氨基己腈的选择性,其中采用原位H2还原的方式进行再生较为适宜。     

Ni-Fe/CaO催化己二腈部分加氢制备6-氨基己腈

与传统工艺相比，丁二烯氢氰化法制备己内酰胺具有绿色、经济、环境友好等特点，其中己二腈（ADN）部分加氢制备6-氨基己腈（ACN）是该工艺的核心步骤。该文以尿素为沉淀剂，采用沉积沉淀法制备了Ni/CaO和Ni-Fe/CaO催化剂，并将其应用于ADN部分加氢制备ACN。XRD结果表明，Fe掺杂后的催化剂生成了FeNi3合金相；TEM结果表明，Fe掺杂后金属Ni变得更加分散。考察了反应温度、反应压力对ADN加氢性能的影响，实验结果表明，在80 ℃、4 MPa、催化剂用量为0.1 g的温和条件下反应2h，ADN转化率为87.5%，ACN选择性为74.4%，失活后的催化剂经过氢气还原后能够重复使用。     

己二腈加氢制备己二胺催化剂的研究进展

简述了己二腈催化加氢的反应机理;根据催化剂形式的不同;综述了己二腈加氢制备已二胺催化剂的研究进展;介绍了Zlegler型催化剂及贵金属络合物均相催化剂、雷尼镍(Raney Ni)型催化剂及非负载型多相催化剂在己二腈催化加氢制备己二胺的应用及其优缺点;详述了负载型催化剂的研究进展及加氢效果;指出工业生产中以Raney Ni型催化剂为主,但使用寿命及环保方面限制其发展,而负载型催化剂在己二腈催化加氢具有较好的应用前景;建议今后应进一步探索己二腈催化加氢中的不同产物生成机理,改进活体的负载方式及助催化剂的研究。     

己二腈催化加氢制己二胺

论述了己二腈在较低温度、较低压力和在稀释剂及催化剂存在的前提下,加氢反应生成己二胺的基本原理,分析各种因素对己二腈加氢反应的影响。     

己二腈加氢用雷尼镍催化剂的开发研究

简单介绍了雷尼镍催化剂的理化性质，国内外雷尼镍催化剂在己二腈加氢反应中的使用状况及存在的差距，国产己二腈加氢用雷尼镍催化剂的开发研究过程，并对其工业化应用进行简单评价。     

骨架镍催化剂在腈类加氢中的应用

介绍3种类型骨架镍催化剂在己二腈加氢中的应用,并对加氢结果进行比较。结果表明,3种类型骨架镍催化剂均可以实现己二腈加氢,己二腈转化率和己二胺选择性较高。同时对其他二腈如2-甲基戊二腈和丁二腈进行加氢研究,进一步表明骨架镍在腈类加氢中具有独特优势。     

雷尼镍催化剂在己二腈加氢反应中的应用与研究

在生产己二胺的工艺中,雷尼镍催化剂作为己二腈加氢反应的主要催化剂。对己二腈加氢反应中的雷尼镍催化剂的物化特性进行介绍,对该催化剂的活化、钝化进行了研究,该催化剂在己二腈加氢反应中的应用及存在的问题进行研究,认为催化剂定量置换可以很好地解决活性降低和流动性变差这一问题。     

己二腈残渣中可水解己二腈聚合物及己二腈含量的测定

本文采用浓硫酸做催化剂将己二腈残渣进行水解,通过水解产生的己二酸的量即可测出其中可水解己二腈聚合物及已二腈的含量,该法操作简便易行。     

电解二聚法生产己二腈工艺流程模拟与优化

在丙烯腈电解制己二腈工艺的基础上,研究开发己二腈分离流程。使用PROⅡ模拟软件对电解液中己二腈的分离提纯工艺进行了模拟优化。考察了理论塔板数、回流比、冷凝温度和压力等因素对同系物分离塔的影响,得到了最佳工艺条件,在此条件下可获得质量分数为99.5%的己二腈,模拟计算结果与实验结果基本相符。     

负载型Ni-B/γ-Al_2O_3非晶态合金催化剂苯加氢性能

采用化学还原法制备了负载型Ni-B/γ-Al2O3非晶态合金催化剂,并对催化剂进行了X射线衍射(XRD)、比表面积检测(BET)、程序升温还原(TPR)表征。以苯加氢为探针反应,在高压微反装置上考察了活化温度、Ni-B摩尔比、Ni质量分数等制备条件对催化剂加氢性能的影响。实验结果表明,Ni-B以非晶态的形式负载在γ-Al2O3载体上,最佳活化温度为200—260℃,Ni-B/γ-Al2O3非晶态合金催化剂最佳Ni-B摩尔比为1∶3.4;Ni质量分数增加使催化剂的加氢活性提高。在反应压力0.5 MPa、氢苯摩尔比4,空速1.0 h-1的条件下,反应温度高于160℃时,苯加氢制环己烷产率均为100%。     

Liquid phase hydrogenation of adiponitrile over directly reduced Ni/SiO2 catalyst

Liquid phase hydrogenation of adiponitrile (ADN) to 6-aminocapronitrile (ACN) and hexamethylenediamine (HMD) was investigated on Ni/SiO₂ catalysts prepared under different conditions. In this reaction, the highly reactive imine intermediate forms condensation byproducts by reacting with the primary amine products (ACN and HMD). A highly dispersed Ni/SiO₂ catalyst prepared by the direct reduction of Ni(NO₃)₂/SiO₂ was found to suppress the condensation reactions by promoting the hydrogenation of adsorbed imine, and it gave excellent hydrogenation activity and primary amine selectivity. Addition of NaOH increased the primary amine selectivity to 79% at the ADN conversion of 86%.     

单斜相与四方相混合晶相组成ZrO2负载镍催化剂催化顺酐选择性加氢

通过调控水热法制备条件制备同为单斜相和四方相混合晶相组成、但织构性质和表面结构性质不同的两种ZrO_2载体,采用浸渍法制备镍质量分数为10%的Ni/ZrO_2催化剂,考察不同反应温度[(150～240)℃]和氢气压力[(3～7)MPa]条件下两种ZrO_2载体负载镍催化剂的顺酐加氢性能。采用XRD、H_2-TPR、H_2-TPD和拉曼光谱等对催化剂进行表征。结果表明,与镍物种发生较强相互作用的ZrO_2负载镍催化剂具有较高的■键加氢活性与选择性,几乎没有■加氢活性,在所考察的反应温度和反应压力范围,催化剂上丁二酸酐选择性均高于95.1%,γ-丁内酯选择性均低于4.9%。与之不同,与镍物种发生较弱相互作用的ZrO_2负载镍催化剂具有较弱的■键加氢活性,然而,该催化剂表现出一定的■加氢活性,并且其■加氢活性随反应温度或反应压力的提高而显著提高。在反应温度240℃、氢气压力5 MPa条件下,γ-丁内酯选择性高达60.6%。推测晶相组成相似的两种ZrO_2载体负载镍催化剂明显的■加氢性能差异与其表面结构性质不同有关。     

Preparation of Ni/SiO 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-methyl-imidazole 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.     

负载型Ni催化剂上对硝基酚加氢合成对氨基酚的研究

研究了以硅藻土、锐钛型TiO2、Al2O3和高岭土为载体制备的负载型Ni催化剂催化对硝基酚加氢制备对氨基酚的活性。采用XRD与TPR技术表征了催化剂的结构与还原性能。负载型催化剂具有单一的对氨基酚选择性。NiO与载体硅藻土和锐钛型TiO2有弱的相互作用,制备的催化剂还原后有较高的催化活性。Al2O3和高岭土与NiO有较强的相互作用,抑制了还原后金属Ni的催化加氢活性。     

载体制备方法对Ni催化剂催化间二硝基苯加氢反应的影响

以正硅酸乙酯为原料,采用溶胶-凝胶法,分别经乙醇超临界干燥和常规干燥制得SiO2气凝胶和干凝胶载体,并以La2O3为助剂,通过浸渍法制备了用于间二硝基苯液相加氢制间苯二胺反应的镍基催化剂,通过BET、XRD、TPR、H2-TPD和活性评价等方法对催化剂的物化性质和催化性能进行了研究.结果表明,虽然以SiO2气凝胶为载体制备的二元镍基催化剂的镍晶粒的粒度较小,但由于金属镍烧结导致它表面存在的活性位相对较少,对反应组分的吸附强度较弱,致使其活性低于SiO2干凝胶负载的二元镍基催化剂.添加La2O3助剂的三元镍基催化剂的活性总体上比二元催化剂要高,其中以SiO2干凝胶为载体制备的三元催化剂具有较高的活性比表面积和适宜的吸附强度,对间二硝基苯加氢反应表现出很高的催化活性,在2.6 MPa、373 K下反应1 h后,间二硝基苯转化率可达97.0%、间苯二胺产率达93.1%.     

助剂引入方式对镍/二氧化硅催化剂结构和加氢性能的影响

采用等体积浸渍法制备了K_2O和La_2O_3改性的Ni/SiO_2催化剂.考察了K_2O和La_2O_3助刑引入方式对Ni/SiO_2催化剂催化间二硝基苯加氢制间苯二胺的影响.并用比表面积法(BET)、程序升温还原实验(TPR)和X射线衍射法(XRD)等对催化剂的结构进行了表征.结果表明,K_2O和La_2O_3的引入方式对Ni/SiO_2催化剂的物化性质和加氢性能影响明显.当K_2O、La_2O_3和Ni以共浸渍方式引入时,大大削弱载体与镍物种之间的相互作用,镍晶粒度变小,分散度增加,催化剂活性显著提高.加入催化剂1.2g、间二硝基苯40g和溶剂乙醇100mL,在3.0MPa、373K条件下反应4.5h后,间二硝基苯的转化率和间苯二胺的选择性分别达到99.8%和99.5%.     

氧化镧助剂对镍/二氧化硅催化剂结构和加氢性能的影响

采用等体积浸渍法制备了La₂O₃改性的Ni/SiO₂催化剂,考察了La₂O₃的引入方法对Ni/SiO₂催化剂催化间二硝基苯加氢制间苯二胺反应性能的影响,并采用XRD、TPR和XPS等表征技术对催化剂的物化性质进行了研究.结果表明,La₂O₃的添加顺序对Ni/SiO₂催化剂的物化性质和加氢性能影响非常明显.当镧以先于镍浸渍方式引入时,将大大削弱载体与镍物种之间的相互作用,镍晶粒度变小,分散度增加,催化剂的活性显著提高,间二硝基苯转化率和间苯二胺收率分别达到97.1%和93.5%.在以镍和镧共浸方式制备的催化剂中,La₂O₃的存在也使Ni/SiO₂催化剂的反应性能有所改善,但效果没有镧先于镍浸渍方式突出.当以先浸镍后浸镧的方式加入助剂时,催化剂中的镍晶粒增大,分散性变差,催化剂的活性大幅度下降.     

XRecent advances in canola oil hydrogenations

Rapeseed oil has been the source of edible oils in many parts of the world. In the last decade, Canadian plant breeders have developed new rapeseed cultivars which yield oil low in erucic acid and meal low in glucosinolates. These cultivars were named “canola” by the Canadian rapeseed industry. Literature on the hydrogenation characteristics of canola oil is limited; however, in recent years, several aspects of canola oil hydrogenations with commercial nickel catalysts have been reported including the formation ofrans-isomers, trisaturated glycerides and physical properties. In addition, as the methods for determination of sulfur compounds in canola oil developed, the effect of some isothiocyanates on the hydrogenation rate was further investigated to determine the relative catalyst poisoning ability of serveral of these sulfur compounds. However, during the last few years, most of the efforts were directed towards development of novel, selective and active catalysts for canola oil hydrogenations. These studies cover a wide range of homogeneous and heterogeneous catalysts including sulfur poisoned nickel, gold supported on silica, arene-Cr(CO)₃, RuCl₂(CO)₂(PPh₃)₂, palladium on carbon, palladium black and nickel and arene-Cr(CO)₃ mixtures. Effects of temperature, pressure, catalyst concentration and catalyst preparation procedure on the hydrogenation rate, selectivity, catalyst life and quality of the oil were examined and compared with that of commercial nickel catalysts. A brief discussion about continous hydrogenations of canola oil with commerical fixed bed catalysts is also included.     

Cumene hydrocracking and thiophene HDS on niobia-supported Ni, Mo and Ni–Mo catalysts

Results are reported on the XPS characterization and catalytic activity in cumene hydrocracking (2.8 MPa, 623 K) and thiophene HDS (2.8 MPa, 523–573 K) of sulfided Ni, Mo and Ni–Mo catalysts supported on alumina and on pure and phosphated niobia. From the XPS results, evidence was obtained for the formation of a surface niobium sulfide with stoichiometry close to NbS₂ during catalyst sulfidation. Sintering of supported nickel during sulfidation occurred to a much smaller extent with the niobia-supported catalysts than with the alumina-supported ones. The dispersion of alumina-supported molybdenum was little influenced by sulfidation, whereas, with the niobia supports, the molybdenum surface concentration increased with sulfidation. With the alumina support, the Ni–Mo combination caused the dispersion of the sulfided nickel to be improved, possibly due to formation of a NiMoS phase. This was not observed with the niobia-supported catalysts.

Reasonable linear correlations were also found between the intrinsic activity for cumene hydrocracking and the amount of sulfided niobium in the catalysts, but the catalysts supported on phosphated niobia had a higher intrinsic activity than the ones supported on pure niobia. In thiophene HDS, the activity of the niobia-supported nickel catalysts was much larger than the activity of the alumina-supported ones. The activity of the niobia-supported molybdenum catalysts was smaller than that of the alumina-supported catalyst. With the bimetallic catalysts, little or no synergy was observed with the niobia-supported catalysts, in sharp contrast with the alumina case.