沉淀剂对Ru-Zn催化剂催化苯选择加氢性能的影响

采用共沉淀法制备Ru-Zn催化剂,考察了沉淀剂种类、沉淀pH值对其催化苯选择性加氢性能的影响,并采用N2物理吸附、XRD、SEM、H2-TPR对催化剂进行了表征。结果表明,以NaOH为沉淀剂,沉淀pH=7时制备的Ru-Zn-f催化剂性能较好,苯转化率为40%时,环己烯选择性为82.70%,且该催化剂重复使用5次后,环己烯选择性仍维持在81%以上,稳定性好,具有较好的工业应用前景。     

Ru-Zn/ZrO_2催化剂的制备及其苯选择性加氢性能研究

采用沉淀还原法制备负载型Ru-Zn/ZrO_2催化剂,研究了制备方式对苯选择性加氢制环己烯催化性能的影响,用扫描电镜、物理吸附仪等设备对催化剂进行表征。结果表明,催化剂制备过程中ZnSO_4·7H_2O的添加顺序对催化剂性能有明显影响;同步添加RuCl_3和ZnSO_4共沉淀还原制备的催化剂性能较优,苯转化率40%时环己烯选择性达83.2%,循环使用5次后,环己烯的收率仍保持在30%以上。     

Pd含量对催化剂加氢脱氧性能的影响

采用浸渍法制备了系列不同Pd含量的催化剂,通过XRD、H_2-TPR、BET等分析表征技术和以油酸甲酯为模型化合物的加氢反应体系,考察了Pd含量对催化剂催化加氢脱氧性能和催化加氢饱和性能的影响。结果表明,适量的Pd有助于提高Pd在载体上的分散度,减小其与载体的相互作用强度,从而可提高催化剂的加氢脱氧性能和加氢饱和性能,也可使油酸甲脂的加氢脱氧方式越容易按加氢脱羧或脱羰的方式进行;2%Pd/γ-Al_2O_3催化剂的催化加氢脱氧转化率和加氢饱和转化率均为100%,且加氢脱氧方式完全按加氢脱羧或脱羰方式进行。     

酸碱性浸渍条件对钯炭催化剂加氢性能的影响

采用氢氧化钠和盐酸调节钯炭(Pd/C)催化剂制备过程中的浸渍液的pH,制备了相应的钯炭催化剂。对Pd/C催化剂的成分、形貌等性质进行表征分析,研究了不同浸渍条件下制备的Pd/C催化剂对苯甲醛和2-氰基吡啶加氢的催化性能。结果表明,酸/碱浸渍方法可有效控制钯颗粒的尺寸大小及分散度。在浸渍液的pH值为3的条件下制备出的Pd/C-1~#催化剂平均粒径为2.78 nm。当浸渍液的pH值为10时,制备的Pd/C-2~#催化剂平均粒径为3.75 nm。对于2-氰基吡啶加氢,采用酸性浸渍条件制备的Pd/C催化剂具有更好的催化效果;而采用碱性浸渍条件制备的Pd/C-2~#催化剂对苯甲醛加氢效果更好。     

苯选择加氢制环己烯Ru系催化剂的研究

用化学还原法制备了苯选择加氢制环己烯Ru系催化剂，其中Ru为活性组分，Cu或其他金属作为助剂，ZrO2为分散剂。研究了助剂Cu及其含量对反应活性及选择性的影响，结果表明，当Cu/Ru=1.5%时，Ru-Fe-Cu-B/ZrO2催化剂在苯转化率较高的情况下，环己烯的选择性也较高，该催化剂具有很好的工业应用前景。     

植物法制备Au/Fe3O4催化剂及其在肉桂醛选择加氢中的应用

负载型纳米Au催化剂在许多还原反应中表现出良好的催化活性和选择性,是一类很有发展前景的选择性加氢催化剂。以侧柏叶提取液为还原Au(III)溶液的生物质,采用原位还原法制备了Au/Fe3O4催化剂,利用TEM、XRD、XPS等方法对催化剂进行了表征,以肉桂醛选择性加氢为模型反应,考察了催化剂的催化性能,并对肉桂醛选择性加氢的工艺条件进行优化,得到最佳制备条件为:Au负载量为1.0%,焙烧温度为200℃。最佳反应工艺条件为:反应温度60℃,反应压力5.0 MPa,催化剂用量为0.30 g,乙醇为溶剂。在此条件下反应3 h,肉桂醛的转化率为86.4%,肉桂醇的选择性为69.3%。     

贵金属和载体对催化剂催化脱氧裂化性能的影响

采用浸渍法制备了一系列分别负载活性组分Pt,Pd,Ru的γ-Al2O3载体催化剂和分别以固体酸γ-Al2O3,Si O2-Al2O3,USY-Al2O3为载体的Pd催化剂。通过XRD、HRTEM、H2-TPR、NH3-TPD、BET等分析表征技术和以油酸甲酯为模型化合物的反应体系,考察了贵金属及载体性质对催化剂催化加氢脱氧性能和催化裂化性能的影响。结果表明:贵金属及其粒子大小是影响催化剂催化加氢脱氧活性的主要因素;载体的酸强度、酸量是影响催化剂催化裂化性能的主要因素。同时,该性能也受比表面积和孔结构特征的影响;Pd/USY-Al2O3在系列催化剂中表现出了良好的催化加氢脱氧活性和最佳的催化裂化活性。     

制备条件对Pd/TiO_2催化剂上对羧基苯甲醛加氢性能的影响

采用浸渍法以TiO2成型载体制备了Pd/TiO2催化剂,考察了浸渍液pH值、Pd负载量、焙烧温度以及还原温度等因素对粗对苯二甲酸(CTA)中的主要杂质对羧基苯甲醛(4-CBA)的加氢精制性能的影响,并采用BET、XPS、XRD、H2-TPR等手段对催化剂进行了表征。结果表明,浸渍液pH值的升高会造成催化剂表面Pd原子富集,导致催化剂比表面积降低。Pd负载量0.5%时,催化剂所提供的活性中心数目足以满足4-CBA加氢所需。适当提高催化剂焙烧温度,有利于含钯前驱体的分解,催化剂还原温度过高时,会造成Pd/TiO2催化剂活性的迅速降低。Pd/TiO2催化剂的适宜制备条件为:浸渍液pH=2.0、Pd负载量0.5%、催化剂焙烧温度400℃、还原温度低于200℃。     

壳聚糖-钯催化剂用于对硝基苯酚的催化加氢

探讨了用于对硝基苯酚加氢的催化剂-Pd-壳聚糖的制备方法和在常温常压下用该催化剂催化对硝基苯酚加氢反应制对氨基苯酚(PAP)的合成路线，并探讨了催化剂制备方法和加氢反应条件对产物收率的影响。在适宜的反应条件下，PAP的收率可以达到92％，质量标准符合医药级。通过与其他用于制PAP的催化剂相比较，Pd—壳聚糖催化剂具有良好的研究与应用前景。     

Effect of Al content on the phase structure and the hydrogenation characteristic of La(Mg_(1-x)Al_x) alloys

1. Introduction Hydrogen-absorbing materials like sodium alanates, advanced BCC alloys, and Mg-based al- loys have been widely investigated [1]. Mg-based alloys are attractive as potential hydrogen storage materials because of their high storage capacity and low cost [2-3]. The hydrogen desorption kinetics has been improved using various methods [4-6], espe- cially alloying. It was reported that the kinetics of hydriding and dehydriding of Mg-based alloys can be improved by alloying with rar…     

Effect of the partial substitution of Mg by Al on the crystal structure and hydrogenation behavior of La2Mg17

The effect of the partial substitution of Mg by A1 on the crystal structure of La2Mg17 has been investigated. It was found that the LaEMgl7 phase disappears after the partial substitution of Mg by Al. The LaE（Mgo.gAl0.1）17 alloy contains La（Mg,AI）12 and La（Mg,Al）2. Further increasing the Al content, the La2（Mg0.8Al0.2）17 alloy consists of La（Mg,Al）12, La（Mg,Al）2, and Mg. The La（Mg0.93Al0.07）12 phase in the La2（Mg0.9Al0.1）17 alloy crystallizes with the ThMn12-type structure in space group 14/mmm （No. 139）. The lattice parameters were determined to be a = 1.03246（7） nm and c = 0.59410（6） nm. In the ThMn12-type structure, AI atoms occupy 8f site but the A1 content is limited. Moreover, the hydrogenation character- istics have also been compared. La2Mgl7 decomposes into LaH3 and MgH2 under hydrogen, but the La（Mgo.93Alo.o7）12 phase can be hydrogenated into LaH3, MgH2, and La3Al11 at 473 K.     

置氢0.55wt.%对电弧增材制造TC4钛合金组织影响的研究

本文研究了置氢0.55wt.%的电弧增材制造TC4钛合金经过HVC氢处理后组织的演变规律。结论表明,电弧增材制造技术制备的TC4钛合金,组织形貌为粗大的柱状β晶,且晶粒内部为片层α集束。经过置氢处理后,由于氢的扩散和对晶界腐蚀的作用,使β晶内部片层α集束变的更加细小,且有氢化物的产生。随后在810℃温度下对置氢钛合金进行淬火,组织中生成了α′ 、α″和亚稳相βM。并在后续的时效除氢过程中,随着马氏体、亚稳相和氢化物的分解,使钛合金组织中柱状β晶内的片层α晶粒得到显著细化,形成交错分布的细针状组织。     

Density functional theory study on hydrogenation mechanism in catalyst-activated Mg（0001） surface

A small amount of Fe3O4 catalyst is known to substantially improve the adsorption and desorption thermodynamics and kinetics of Mg-based materials. Using density functional theory in combination with nudged elastic band method, the dissociative chemisorptions of hydrogen on both pure and Fe-doped Mg(0001) surfaces were studied. The adsorption energy calculations show that a weakly physisorbed state above pure and Fe-doped Mg surface atoms can serve as a precursor state to dissociative chemisorption. Then, the dissociation pathway of H2 and the relative barrier were investigated. The calculated dissociation barrier (1.08 eV) of hydrogen molecule on a pure Mg(0001) surface is in good agreement with comparable experimental and theoretical studies. For the Fe-doped Mg(0001) surface, the activated barrier decreases to 0.101 eV due to the strong interaction between the s orbital of H and the d orbital of Fe.     

添加剂对钛酸铝陶瓷性能的影响(英文)

研究了添加剂对钛酸铝陶瓷的体积密度、物相组成、机械强度以及抗热震性的影响。用反应烧结法制备钛酸铝陶瓷,其中添加剂为MgO、SiO2、Fe2O3及其复合添加剂。通过阿基米德排水法测试陶瓷的体积密度及气孔率,采用三点弯曲方法测试陶瓷强度,并利用热循环实验测定陶瓷抗热震性。结果表明:MgO、SiO2、Fe2O3及其复合添加剂有利于减少气孔率,提高钛酸铝陶瓷强度,增强陶瓷抗热震性。添加剂能促进烧结,形成新相,并且可以提高钛酸铝的晶格常数c。     

Influence of rare earth promoters on the performance of Ni/Mg（Al）O catalysts for hydrogenation and steam reforming of toluene

CeO₂-, La₂O₃-, and ZrO₂-promoted Ni/Mg(Al)O catalysts synthesized by hydrotalcite-type precursors have been investigated with respect to catalytic activity and carbon formation in the hydrogenation and steam reforming of toluene as a model tar compound. X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) specific surface area and H₂-temperature programmed reduction (TPR) were used to observe the characteristics of the prepared catalysts. The carbon formation and its amount on the used catalysts were examined by transmission electron microscope (TEM), scanning electron microscope (SEM) and thermogravimetric (TG). The trend of catalytic activity as derived from the experimental results followed the order: Ni-Ce>Ni-Las>Ni-Zr>Ni. The catalyst modified with CeO₂ exhibited the highest catalytic performance and had good carbon resistance in the hydrogenation and steam reforming of toluene. A toluene conversion of 96.8%, a CH₄ yield of 45.2% and a CO yield of 50.4% have been achieved. The addition of promoters led to better dispersion of nickel species and higher interaction nickel-support, which were favorable for increasing the catalytic activity and effectively preventing carbon formation.