负载型双金属催化剂催化间苯二甲腈加氢制备间苯二甲胺

采用浸渍法制备活性炭负载Ni、Ru、Rh单金属及Ni-Ru、Ru-Rh双金属催化剂,考察反应温度、反应压力和m(催化剂)∶m(间苯二甲腈)对间苯二甲腈加氢制备间苯二甲胺的影响。结果表明,Ni-Ru/C催化活性高于Ru/C和Ni/C,通过分步浸渍法制备的Ni-Ru/C催化活性优于一步浸渍法。以甲醇和甲苯为混合溶剂,在m(催化剂)∶m(间苯二甲腈)=1∶20、反应温度120℃、反应压力4.0 MPa和1 000 r·min-1条件下,无需加入碱性抑制剂,间苯二甲胺收率最高可达97.78%。     

高活性骨架镍温和条件下催化间苯二甲腈加氢制备间苯二甲胺

将骤冷法制备的非晶态NiAl合金薄条,经粉碎、碱活化后,制备出高活性的骨架镍,发现其对于间苯二甲腈催化加氢制备间苯二甲胺具有极高的活性和选择性。研究了溶剂、催化剂用量、原料初始浓度、温度、压力等因素对间苯二甲胺收率和选择性的影响。结果表明,在以甲醇作为溶剂、原料初始浓度1.5 mol/L、催化剂质量为原料质量的3%~6%、80℃、1.5~2.0 MPa,并添加适量碱性助剂的条件下反应150 min,间苯二甲腈转化率可达99.9%,间苯二甲胺的摩尔收率可达96.0%。     

载体焙烧温度对Ni/SiO2-Al2O3催化剂稳定性的影响

为了获得高水热稳定的负载Ni催化剂,延长催化剂在含水液相体系中的使用寿命,以不同温度焙烧的SiO₂-Al₂O₃为载体,采用浸渍法制备Ni/SiO₂-Al₂O₃催化剂,通过吡啶-原位傅立叶变换红外光谱、X射线衍射、NH₃-程序升温脱附和H₂-程序升温还原等方法进行表征,以水相1,4-丁炔二醇加氢为探针反应,研究载体焙烧温度对Ni/SiO₂-Al₂O₃催化剂催化加氢性能及含水体系中稳定性的影响。结果表明,在(400~800) ℃,随着载体焙烧温度升高,活性组分Ni存在状态及催化剂加氢活性变化较小,但催化剂的水热稳定性下降,造成这一现象的原因是随着载体焙烧温度升高,载体表面SiO₂聚集,暴露的Al³⁺增加,载体水合程度增大。载体焙烧温度400 ℃时,Ni/SiO₂-Al₂O₃催化剂表现出最佳的水热稳定性。     

溶剂热浸渍法制备高稳定性Zn(OAc)2/SiO2催化剂及其催化合成苯氨基甲酸甲酯

Zn(OAc)₂对由碳酸二甲酯（DMC）和苯胺合成苯氨基甲酸甲酯（MPC）的反应具有优异的催化性能,但存在易失活、不能重复使用的缺点。为此,以DMC为溶剂,利用溶剂热浸渍法制备Zn(OAc)₂/SiO₂催化剂,并对其催化性能进行了研究。利用XRD、FTIR和TG-DTA等方法对其进行了表征,结果表明,Zn(OAc)₂/SiO₂催化剂表面存在Zn(OAc)₂和ZnO,且其在SiO₂表面分散较好;优化了Zn(OAc)₂/SiO₂催化剂的反应条件,当反应温度为190℃、反应时间为5h、苯胺与DMC的摩尔比为1∶20、催化剂与苯胺质量比为0.2时,苯胺的转化率为97.2%,MPC的选择性为89.4%。和等体积浸渍法制备的催化剂相比,溶剂热浸渍法制备的Zn(OAc)₂/SiO₂催化剂具有较好的稳定性,重复使用7次,苯胺的转化率下降至79.1%,MPC的选择性下降至79.2%。Zn(OAc)₂/SiO₂活性下降的原因是由于ZnO的生成,并对其进行了再生,再生后的催化剂活性与新鲜催化剂接近。     

间苯二甲胺合成工艺研究

本文对间苯二甲腈合成间苯二甲胺的工艺条件进行了研究。实验证明了反应温度，催化剂的制备方法及用量，不同种溶剂及溶剂比，对产品收得率有很大的影响，由此得出间苯二甲胺合成的优惠工艺条件。     

间苯二甲胺合成工艺研究

以间苯二甲腈为原料,雷尼镍为催化剂,进行催化加氢制间苯二甲胺,探讨了各种因素对反应结果的影响,即:间苯二甲腈原料纯度、催化剂、反应助剂、反应温度、反应压力及反应溶剂等对催化加氢反应的影响。提出间苯二甲腈催化加氢制间苯二甲胺工艺的最佳控制条件。指出对原料间苯二甲腈的纯化及催化剂的研究是今后间苯二甲腈催化加氢制备间苯二甲胺实现工业化的研究重点。     

间苯二甲腈加氢制间苯二甲胺催化剂研究

采用浸渍法制备了间苯二甲腈加氢合成间苯二甲胺所用的催化剂。详细考察了负载金属类型、金属负载量(质量分数)、载体类型、焙烧温度、还原温度等条件对催化剂性能的影响。结果表明,采用Ni/Al_2O_3催化剂,当镍负载量为10%,焙烧温度为723 K,还原温度为773 K时,催化剂的反应性能最好,间苯二甲腈转化率为99%,间苯二甲胺选择性为98%。     

间苯二甲胺的合成与应用

综述了间苯二甲胺的合成方法,分析了以间苯二甲腈为原料、经Co和Ni为主催化剂催化加氢制备间苯二甲胺的工艺。对间苯二甲胺在环氧树脂固化剂、聚氨酯等产品生产中的应用进行了阐述。     

静电纺丝法制备高活性多孔Ni/SiO2甲烷化催化剂

以三嵌段共聚物P123为模板剂,采用静电纺丝法制备了多孔Ni/SiO₂催化剂,考察其在CO甲烷化中的催化性能。采用N₂物理吸脱附测试、扫描电子显微镜（SEM）、X射线衍射（XRD）、H₂-程序升温还原（H₂-TPR）、透射电子显微镜（TEM）、热重分析（TGA）对催化剂的结构性质进行表征。结果表明,静电纺丝法制备的多孔Ni/SiO₂催化剂活性组分Ni在SiO₂载体纤维上高度分散,比表面积大,Ni颗粒尺寸小,金属与载体相互作用强,在CO甲烷化反应中表现出优异的催化活性和稳定性。在温度450℃,压力0.1 MPa,质量空速15000 ml/（g·h）条件下,多孔Ni/SiO₂催化剂CO转化率最高可达96.4%,CH₄选择性可达86.4%。此方法为工业上制备高催化活性且无须二次成型的甲烷化催化剂提供了新思路。     

间苯二甲腈催化加氢制备间苯二甲胺的研究进展

综述了近年来国内外间苯二甲腈催化加氢制备间苯二甲胺的研究进展,回顾了催化剂改进的过程,讨论了溶剂、原料初浓度、反应抑制剂、反应压力、反应温度等条件对催化加氢反应的影响,介绍了催化加氢工艺流程的改进和产物分离工艺的发展情况。指出对间苯二甲腈和间苯二甲胺热力学物性及该反应的反应历程、反应动力学等的基础研究和工艺流程的改进是今后间苯二甲腈催化加氢制备间苯二甲胺实现工业化的研究重点。     

均匀沉淀法制备负载型双金属催化剂的正交实验研究

以NiCl2·6H2O和Co(NO3)2·6H2O为原料,CO(NH2)2为沉淀剂,Al2O3为载体,采用均匀沉淀法制备了负载型双金属催化剂(Ni-Co/γ-Al2O3).利用正交实验探讨了不同工艺参数对催化剂合成的影响,并得出了最佳制备工艺.实验得出的最佳工艺参数为:n(NiCl2·6H2O)/n(Co(NO3)2·...     

Ni-Cu/γ-Al2O3催化剂的制备及其脱氢反应研究

采用共沉淀法、浸渍法和共沉淀-浸渍法制备了3种不同的Ni-Cu/γ-Al2O3双金属催化剂,并利用微型连续管式反应器,考察了3种Ni-Cu/γ-Al2O3催化剂对氢能载体甲基环己烷(MCH)气相脱氢的催化性能。采用XRD、SEM、BET、BJH等手段对所制备的催化剂进行表征。结果表明,使用共沉淀-浸渍法制备的Ni-Cu/γ-Al2O3催化剂优于其他两种〔3种催化剂中Ni和Cu负载量均为26%且n(Ni)∶n(Cu)=8∶1〕。在反应温度673K,反应压力0.6 MPa,MCH与N2体积流量比为19∶27,混合进样体积空速240 h-1条件下,MCH脱氢转化率达到98.5%,产物甲苯的选择性接近100%。与铂等贵金属催化剂以及单金属镍催化剂相比,镍铜双金属催化剂在该反应中具有更好的应用前景。     

Au–Cu alloy nanoparticles supported on silica gel as catalyst for CO oxidation: Effects of Au/Cu ratios

Au–Cu bimetallic catalysts with Au/Cu ratios ranging from 3/1 to 20/1 were prepared on silica gel support by a two-step method. The catalysts were characterized by ICP, XRD and TEM. The results showed that, irrespective of Au/Cu ratios, all the bimetallic nanoparticles had significantly reduced particle sizes (3.0–3.6 nm) in comparison with monometallic gold catalysts (5.7 nm). Both CO oxidation and PROX reactions were employed to evaluate the catalytic activities of Au–Cu bimetallic catalysts. For CO oxidation, the alloy catalysts show non-monotonic temperature dependence showing a valley in the intermediate temperature range. The catalyst with Au/Cu ratio of 20/1 gave the highest activity at room temperature, but its activity showed the deepest valley with increasing the reaction temperature. On the other hand, the catalyst with Au/Cu ratio of 3/1 exhibited the best performance for PROX reaction. For the Au/Cu ratios investigated, the bimetallic catalysts showed superior performance to monometallic gold catalysts, demonstrating the synergy between gold and copper.     

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%.     

Sulphide catalysts on silica as a support: VIII. Peculiarities of thiophene hydrogenolysis and probable nature of “synergetic effect”

The main kinetic features of thiophene hydrogenolysis on mono- and bimetallic sulphide catalysts were analyzed. Sulphide molybdenum and tungsten catalysts were shown to differ from nickel catalysts in that they exhibited higher hydrogenation activity. According to the data from the temperature-programmed reduction (TPR) the amount of sulphur removed at TPR was not functionally dependent on the activity of bimetallic sulphide catalysts in thiophene hydrogenolysis. A new reaction mechanism of thiophene hydrogenolysis is proposed with consideration given to the structure of the active component of bimetallic catalysts. The adsorption and activation of a thiophene molecule is supposed to occur on nickel atoms stabilized on the side planes of MoS₂ (WS₂) single slabs, while hydrogen activation is achieved on the Mo(W) atoms. A high rate of chemical reaction seems to be achieved by synchronous interaction of thiophene and hydrogen molecules in the coordination sphere of a bimetallic sulphide species in the rate-determining reaction step.     

Characterization of bimetallic rhodium-germanium catalysts prepared by surface redox reaction

The preparation of bimetallic rhodium-germanium/silica and rhodium-germanium/alumina catalysts was investigated by controlled surface reaction. Their catalytic performances were measured for two gas phase reactions (toluene hydrogenation at 323 K and cyclohexane dehydrogenation at 543 K) and for a liquid phase reaction (citral hydrogenation at 343 K).

Elemental analysis of bimetallic catalysts showed that germanium can be deposited by redox reaction between hydrogen activated on a parent monometallic rhodium catalyst and germanium tetrachloride dissolved in water (catalytic reduction method). EDX microanalysis of rhodium-germanium/silica catalysts indicated that rhodium and germanium were deposited in close contact on the silica support. However, on alumina-supported catalysts, germanium deposition occurred also separately on the support. For the different test reactions, the catalytic properties of rhodium were strongly altered by the addition of germanium. On alumina-supported catalysts, interesting catalytic effects were observed in citral hydrogenation when not only close contact exists between both metals but when, in addition, the second metal was deposited on the support in the close vicinity of rhodium.     

Benzene hydrogenation over Ni-Cu/SiO2 catalysts prepared by aqueous hydrazine reduction

Non conventional nickel (1%) and nickel (1%)-copper (0.2%-0.75%) catalysts supported on silica have been prepared by aqueous hydrazine reduction of nickel acetate at 70 °C. They were characterized by TEM, H₂-adsorption, H₂-TPD and tested in the gas phase hydrogenation of benzene at atmospheric pressure in the temperature range 75 °C-230 °C. The obtained results show that nickel is in a whisker-like shape or as a film of low density for the Ni/SiO₂ and Ni-Cu/SiO₂ catalysts respectively. Copper is in the shape of facetted particles in the mono or bimetallic systems with a mean particle size varying from 25 to 100 nm. The presence of copper decreased the nickel phase dispersion as well as the conversion whereas it increased carbon deposit in benzene hydrogenation. The results obtained are ascribed to nickel phase shape changes and Ni-Cu interactions. A kinetic reaction mechanism model is proposed. The comparative study of a pair of classical/non-classical Ni/SiO₂ catalysts showed much higher surface and catalytic properties of the hydrazine catalyst.