硫醇修饰近亚纳米尺度Pd乙炔加氢性能研究

通过浸渍法以及配体保护液相还原再负载法分别合成Pd/SiO_2、Sc12-Pd/S_2-SiO_2催化剂,考察了不同催化剂乙炔选择加氢合成乙烯性能,并通过IR、UV-Vis、TEM等对催化剂进行表征。结果表明,正十二硫醇配体保护液相还原再负载可以合成负载尺寸均匀的近亚纳米Pd催化剂,硫醇能够修饰Pd颗粒促进乙炔选择加氢合成乙烯。与浸渍法合成的硫醇修饰Sc12-Pd/SiO_2催化剂相比,硫醇修饰负载的近亚纳米尺寸的Sc12-Pd/S_2-SiO_2催化剂具有更高乙炔选择加氢合成乙烯性能。     

乙炔选择加氢催化剂的研究

采用固定床连续流动反应器对12%Ni/CNF、0.5%Pd/CNF、0.5%Pd/α-Al2O33种催化剂上的乙炔加氢反应进行了研究。考察了反应温度、n(H2)/n(C2H2)以及总空速对反应的影响,得到了在n(H2)/n(C2H2)较宽的范围内乙炔加氢为乙烯具有良好选择性的催化剂0.5%Pd/CNF。在50℃,n(H2)/n(C2H2)=23,乙炔空速为106h-1时,乙炔转化率达100%,乙烯收率为64.8%,乙烯选择性为73.8%。     

乙炔选择加氢催化剂研究进展

选择加氢是去除蒸汽裂解制烯烃过程中所产生微量乙炔的有效方法,高效乙炔选择加氢催化剂的开发具有重要意义。介绍了催化剂类型[单元贵金属、非贵金属及双（多）元金属]及其催化性能,分析了载体、助剂和制备方法对催化剂结构和性能的影响,重点讨论了几何和电子因素对催化剂乙炔选择加氢性能的决定作用。     

工业尾气中乙炔、乙烯加氢催化剂的研制

实验室研究及工业侧流试验表明，研制的CH-101及CH-201型加氢催化剂能有效地脱除原料气中的乙炔、乙烯，具有活性好、净化度高等特点，其性能优于国外同类产品。     

乙炔选择加氢催化剂的研究进展

工业上脱炔的方法主要通过选择性加氢,文章从金属分散度、载体性质以及配体等方面分析了乙炔选择加氢催化剂的研究情况,提出了催化剂选择性改进的途径。     

乙炔选择性加氢催化剂的研究进展

乙烯主要通过石脑油和柴油热裂解制取,乙烯原料气中带有体积分数为0.3%～3%的乙炔,该微量乙炔会毒化乙烯聚合催化剂。工业上通常用选择加氢法将乙炔转化为乙烯,但钯基催化剂一直都存在选择性低、稳定性差等缺点。梳理近几年对乙炔选择性加氢反应及其催化剂的研究,并探讨制备方法、活性组分、助剂和载体对催化剂结构和性能的影响;叙述不同催化剂的制备方法在乙炔加氢反应中的应用,制备方法可以有效改变活性组分的表面物理性质,影响活性组分对乙烯的吸脱附性能。最后,展望了乙炔加氢催化剂未来的研究方向。     

微量乙炔和乙烯加氢催化剂的研制

介绍了乙炔尾气中微量乙炔和乙烯加氢催化剂的研制过程。结果表明，研制的CH-101及CH-201型加氢催化剂能有效地脱除原料气中的乙炔及乙烯，具有活性好、净化度高等特点。     

加氢除乙炔反应

二氯乙烷裂解生成的HCl中含有乙炔，降低了氧氯化单元EDC产品的纯度，增加了EDC精制处理过程的能量消耗。通过加氢反应，消除了HCl中乙炔造成的不良影响，取得了节能降耗的效果。     

负载型纳米金催化剂在乙炔选择性加氢反应中的研究进展

介绍了乙炔选择性加氢制乙烯催化剂的研究和开发进展。针对负载型纳米金催化剂的发展趋势及其对乙炔加氢反应产物中乙烯的独特选择性,重点对比单金属纳米金催化剂及合金型催化剂的催化性能差异,发现合金型纳米金催化剂具有较高的乙炔转化率和稳定性。影响催化性能的主要因素有纳米粒子的大小及活性组分之间的相互协同作用。分析积炭的形成以及导致催化剂失活的原理。展望低温条件下具有高转化率与高稳定性的合金型纳米金催化剂的应用前景。     

Catalytic performance of a Ti added Pd/SiO2 catalyst for acetylene hydrogenation

A series of Pd/SiO₂ and Pd–Ti/SiO₂ catalysts were prepared by the incipient wetness impregnation method. The catalytic performance for selective hydrogenation of acetylene to ethylene was measured under “high concentration acetylene”, “high space velocity” and “no dilution gas” conditions. The crystal structure and particle size of the catalysts were characterized by the X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), nitrogen physisorption using the BET method and transmission electron microscope (TEM). The results showed that the titanium oxide in Pd–Ti/SiO₂ catalyst was amorphous and the addition of Ti reduced the particle size of Pd significantly. Comparing to the Pd/SiO₂ catalyst, the ethylene yield increased from 64.1% to 88.3% under Pd–Ti/SiO₂ catalytic system.     

Properties of Si-modified Pd catalyst for selective hydrogenation of acetylene

Supported Pd catalysts have been modified with Si deposited on them by silane decomposition. When used in acetylene hydrogenation, the Si-modified catalysts show higher selectivity for ethylene and produce less amount of green oil than the unmodified Pd catalysts. IR and XPS analyses of the catalysts suggest that Si covers the Pd surface as Si or SiO₂ patches. The Pd surface is diluted with the deposited Si as observed by IR spectra of CO adsorbed on the surface. However, the electronic property of the Pd surface seems to be unaffected by the Si species because such a modification is not observed in XPS nor acetylene-TPD analysis. Accordingly, we conclude that improved performance of the Si-modified catalysts comes mostly from geometric modification of the Pd surface by Si.     

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。     

Dual effect of TiO2 vacancy on Pd catalyst in acetylene hydrogenation: Boosting performance and capturing reaction heat

Selective acetylene hydrogenation is a strongly exothermic process, easy to cause coking and metal agglomeration, and thus leads to deactivation. In this work, Pd/TiO₂ with different oxygen vacancies (V_o) were synthesized by controlling reduction temperature in 300–700°C, in which Pd/TiO₂-HT300 (HT is reduction temperature) possessed the highest V_o content. It was found highly dispersed Pd nanoparticles adjacent to more V_o exhibited enhanced catalytic behavior (near 100% conversion at 55°C with 80% selectivity and turnover frequency of 0.12 s⁻¹) due to hydrogen spillover generation and electron donation originating from V_o sites, confirmed by in situ x-ray photoelectron spectroscopy, in situ Raman, and H₂-temperature programmed desorption. More importantly, the increasing V_o sites trap the released heat and devote to a decrease of heat accumulation over a single active Pd site, and consequently inhibit Pd agglomeration and polymerization, affirmed by high-resolution transmission electron microscopy, CO chemisorption, and thermogravimetric analysis.     

碱土金属镁对乙炔前加氢催化剂性能的影响

以α-Al_2O_3为载体,Pd为主活性组分,Ag为助活性组分,经过碱土金属Mg改性,制备了乙炔加氢催化剂。与国外对比催化剂微反对比评价结果表明,Mg改性的乙炔前加氢催化剂初期活性略差,但随着反应时间延长,Mg改性的乙炔前加氢催化剂活性高于国外对比催化剂,其选择性均高于国外对比催化剂。原位红外分析表明,催化剂经过碱土金属Mg改性后,酸性低于国外对比催化剂,减少了齐聚等副反应的发生,提高了催化剂的抗结焦性能。     

Selective hydrogenation of acetylene over Pd/CeO2

Five hundred ppm Pd/CeO₂ catalyst was prepared and evaluated in selective hydrogenation of acetylene in large excess of ethylene since ceria has been recently found to be a reasonable stand-alone catalyst for this reaction. Pd/CeO₂ catalyst could be activated in situ by the feed gas during reactions and the catalyst without reduction showed much better ethylene selectivity than the reduced one in the high temperature range due to the formation of oxygen vacancies by reduction. Excellent ethylene selectivity of ~100% was obtained in the whole reaction temperature range of 50°C–200°C for samples calcined at temperatures of 600°C and 800°C. This could be ascribed to the formation of Pd_xCe_1−xO_2−y or Pd-O-Ce surface species based on the X-ray diffraction and X-ray photoelectron spectroscopy results, indicating the strong interaction between palladium and ceria.     

乙烯基乙炔选择加氢制丁二烯工艺研究

采用硝酸钯二水化合物(Pd(NO₃)₂·2H₂O)通过等体积浸渍法制备负载型Pd催化剂,在其催化下,乙烯基乙炔(MVA)选择加氢制丁二烯;研究负载型Pd催化剂的制备工艺以及MVA选择加氢制丁二烯的工艺条件,并对催化剂的催化性能及加氢效果进行表征。结果表明:以氧化铝(α-Al₂O₃)为载体,负载Pd质量分数为0.08%,还原温度400℃时,制备的负载型Pd催化剂(Pd/α-Al₂O₃)结晶良好,对载体结构的影响不明显,催化剂的孔结构比较均匀,对MVA选择加氢反应的催化性能好;在MVA选择加氢催化剂评价装置上,在Pd/α-Al₂O₃催化下进行MVA选择加氢反应,较佳工艺条件为反应温度30℃、MVA空速100 mL/(h·g)、炔氢比1.2,反应的主要产物为丁二烯,MVA转化率达到50%,丁二烯选择性达到85%。     

Preparation and investigation of Pd doped Cu catalysts for selective hydrogenation of acetylene

A series of PdCu bimetallic catalysts with low Cu and Pd loadings and different Cu: Pd atomic ratios were prepared by conventionally sequential impregnation (CSI) and modified sequential impregnation (MSI) of Cu and Pd for selective hydrogenation of acetylene. Characterization indicates that the supported copper (II) nitrate in the PdCu bimetallic catalysts prepared by MSI can be directly reduced to Cu metal particles due to the hydrogen spillover from Pd to Cu(NO₃)₂ crystals. In addition, for the catalysts prepared by MSI, Pd atoms can form PdCu alloy on the surface of metal particles, however, for the catalysts prepared by CSI, Pd tends to migrate and exist below the surface layer of Cu. Reaction results indicate that compared with CSI, the MSI method enables samples to possess preferable stability as well as comparable reaction activity. This should be due to the MSI method in favor of the formation of PdCu alloy on the surface of metal particles. Moreover, even Pd loading is super low, <0.045 wt-% in this study, by through adjusting Cu loading to an appropriate value, attractive reactivity and selectivity still can be achieved.     

负载型Pd/SBA—15催化剂催化性能研究

将负载型催化剂Pd/SBA—15用于催化邻氯硝基苯加氢。考察了反应温度、催化剂用量对Pd/SBA—15催化性能的影响,并考察了催化剂的使用寿命。实验结果表明,Pd/SBA—15催化剂表现出很好的催化性能,有望应用于工业生产。     

Selective hydrogenation of acetylene on Nanosized catalysts

The use of unconventional methods for the preparation of Nanosized catalysts for the selective hydrogenation of acetylene and its homologs is considered. Based on published data and experimental data obtained in this work, it is shown that catalysts based on nanoparticles of palladium have a high activity, although their selectivity and stability are low. Bimetallic palladium-containing systems are more promising. The most interesting of them are nanocomposites containing palladium and silver or palladium and zinc particles. Another method that makes it possible to increase the selectivity and stability of the catalysts for the hydrogenation of triple bonds is the use of synergism in gold-nickel nanocomposites. The preparation of nanosized hydrogenation catalysts by a recently developed method of laser electrodispersion is considered. This method makes it possible to prepare catalysts with a very narrow distribution of nanoclusters over sizes and with very high specific activity and stability.