CoB/C催化硼氢化钠水解制氢的性能

使用浸渍负载-还原法及化学镀法制备了活性炭负载的CoB催化剂,研究了这些催化剂催化硼氢化钠水解制氢反应的性能。在温度为20℃,反应液为1%NaBH4+5%NaOH的条件下,浸渍负载-还原法制备的CoB/C催化剂的产氢活性为2 022mL.min-1.g-1(Co),而化学镀法制备的CoB/C催化剂的产氢活性可达2 503 mL.min-1.g-1(Co),相同条件下非负载的CoB催化剂的产氢活性仅为1 351 mL.min-1.g-1(Co)。化学镀法制备的CoB/C催化剂重复使用5次后其活性仍能保持初始活性的70%,而浸渍负载的CoB/C催化剂及非负载的CoB催化剂的活性分别降至初始活性的30%和10%,化学镀法制备的CoB/C催化剂显示出更好的催化性能。此外该催化剂在空气中放置30 d后催化活性没有明显下降,这为其存储和使用带来了便利。进一步的物理化学表征表明,非负载的CoB极易团聚,形成的二次粒子粒径在400~800 nm,而活性炭负载的CoB催化剂团聚现象则大大减弱,CoB的分散性明显好于非负载催化剂。载体的存在可进一步阻止CoB活性组分在催化反应过程中发生团聚而避免活性下降。化学镀法制备的催化剂中,载体与CoB之间有更强的相互作用而使得后者结合紧密,分散良好,不易流失,催化剂整体上具有更好的稳定性。     

石墨烯负载Pt/Co双金属纳米颗粒催化剂的制备及催化制氢性能

采用化学共还原方法制备了石墨烯负载Pt/Co双金属纳米颗粒（GBNPS）催化剂,并将其用于催化硼氢化钾（KBH₄）水解制氢.采用透射电子显微镜（TEM）、X射线衍射（XRD）仪和X射线光电子能谱（XPS）表征了该催化剂,并研究了双金属纳米颗粒的化学组成对其催化KBH₄水解制氢性能的影响.结果表明,制备的石墨烯负载Pt/Co双金属纳米颗粒平均粒径为3.2~3.9 nm,其中石墨烯负载Pt₂₀Co₈₀双金属纳米颗粒的催化活性最高,35℃时制氢活性可达35973 mol_H2·h^-1·mol^-1_Pt,且具有良好的耐久性,催化KBH₄水解反应的表观活化能为36 kJ/mol.     

PdAg/MIL-101(Fe)催化NaBH4水解制氢

将PdAg纳米颗粒负载到MIL-101(Fe)上作为硼氢化钠水解制氢的催化剂。采用XRD、TEM、HRTEM、XPS、SEM和EDS等方法对催化剂PdAg/MIL-101(Fe)的结构进行了表征。PdAg/MIL-101(Fe)在硼氢化钠水解制氢中表现出较高的催化活性,在温和的条件下水解制氢最大速率为2.60 L·min^–1·g_cat.^–1。详细研究了反应温度、催化剂用量、氢氧化钠和硼氢化钠浓度对该催化反应的影响规律。结果发现,制氢速率很大程度上依赖于反应温度,随着反应温度的升高,制氢速率明显增加,制氢的表观活化能为54.89 kJ·mol^–1。该催化剂重用性能好,5次循环后仍能保持活性。     

硼氢化钠催化水解制氢*

硼氢化钠（NaBH₄）催化水解制氢是一项具备车载氢源应用前景的储氢/制氢一体化技术。本文介绍了该技术催化水解制氢的原理,综述了制氢催化剂、反应动力学、反应机理、反应装置的设计和反应副产物回收利用的最新研究进展,讨论了该技术研发中需解决的问题。水解制氢系统的实际应用需研发高效、耐久性负载型催化剂。制氢装置的设计应考虑反应热的综合利用、燃料电池产生的水循环利用及膜分离技术的应用。NaBH4的高效再生将降低其生产成本,实现NaBH4基水解制氢系统的商业化应用。     

钙钛矿型甲醇水蒸气重整制氢催化材料的研究

采用溶胶凝胶法合成了钙钛矿复合氧化物, 负载氧化铜后得钙钛矿负载型催化材料, 通过XRD (X射线衍射分析)、BET(比表面积测试)、H₂-TPR(程序升温还原分析)、XPS (X射线光电子能谱)等手段对催化材料进行了表征, 考察了不同种类钙钛矿负载纳米铜催化材料的结构、性质对甲醇水蒸气重整制氢性能的影响. 结果显示, 钙钛矿负载纳米铜催化材料的催化活性主要与催化剂的铜比表面积、表面晶格氧缺位以及活性组分和载体间的相互作用有关. 其中, CuO/LaCrO₃钙钛矿负载型催化材料的表面氧空穴含量较多, 活性组分与载体间相互作用较强, 因此催化甲醇水蒸气重整制氢活性较好. 当反应温度为360 ℃时, CuO/LaCrO₃钙钛矿型催化剂并未出现明显失活现象, 甲醇转化率为98.6%, 产氢速率为694.9 mL•kg_cat ^–1•s ^–1.     

配位还原制备膦酸功能化Pd/C催化剂及其应用

采用活性炭为载体,乙二胺四亚甲基膦酸（EDTMPA）作为配位剂和稳定剂,氯化钯（PdCl₂）为前驱体,硼氢化钠（NaBH₄）为还原剂,通过一步还原制备得到膦酸功能化的超细高分散Pd/C催化剂.透射电子显微镜（TEM）及X射线衍射（XRD）分析结果表明,制得的Pd/C催化剂中Pd粒子的平均粒径为2.7 nm,分散度为37.1%,高于同类型商业化催化剂.制得的催化剂对罗丹明（RhB）和对硝基苯酚（4-NP）的催化加氢反应的活化能分别为27.18和16.79 kJ/mol,明显低于商业化Pd/C催化剂（57.12和55.71 kJ/mol）.     

前驱体干燥法对非晶态Ni-B/γ-Al2O3催化剂性能的影响

将非晶态合金负载于大比表面积多孔氧化物载体上既可保留非晶态合金特有的结构和性质, 又能降低非晶态合金粒子的表面能, 提高催化剂的热稳定性[1～6]. 迄今为止, 绝大多数负载型非晶态催化剂的前驱体均以盐溶液浸渍载体后于110 ℃一步烘干获得. 但用该法制得的前驱体经还原后的活性比表面积和活性组分的分散度较低, 导致催化剂的效率不高. 本文设计了两步干燥法, 制得的负载型非晶态Ni-B/γ-Al2O3催化剂用于液相苯加氢制备环己烷. 结果表明, 两步干燥法提高了载体表面非晶态活性组分的分散度. 与传统的一步干燥法制备的催化剂相比, 催化剂的热稳定性及其在苯加氢反应中的催化活性大大提高.     

载体对非晶态NiB合金催化性能影响的比较

各种负载型非晶态NiB合金表现出优良的苯加氢催化活性.其活性与载体的表面积成正比关系,高比表面积的载体更有利于NiB合金的分散,使催化剂具有更多的活性位.TPR结果表明非晶态NiB合金负载在不同的载体上表现出不同的分散状态.与γ-Al2O3相比较,海泡石和膨润土有更高的催化活性和抗硫性能,作为催化剂载体,具有很好的应用前景.     

Ni含量对Co_(1-x)Ni_xB催化水解放氢性能的影响(英文)

采用化学还原法以乙醇为溶剂在冰水浴中合成了一系列Co1-xNixB合金催化剂,研究了该系列合金不同Ni含量对NaBH4水解放氢性能的影响.X射线衍射(XRD),扫描电镜(SEM)和透射电镜(TEM)显示Co1-xNixB合金是纳米非晶态颗粒.放氢测试表明Co1-xNixB具有很高的催化活性.放氢速率先随着Ni含量的增加而增大,并在x=0.15时放氢速率达到最大值,然后随x值的增加而减小.298K时Co0.85Ni0.15B合金催化碱性硼氢化钠水解的最大放氢速率可达4228mL·min-1·g-1,CoB和Co0.85Ni0.15B合金催化放氢的活化能分别为34.25和31.87kJ·mol-1.因此以乙醇为溶剂合成的Co1-xNixB合金具有较高的催化活性.     

以壳聚糖为介质的Ni-B非晶态合金/膨胀石墨的制备及其催化加氢性能

以膨胀石墨担载壳聚糖,采用金属诱导化学镀法制备了负载型Ni-B非晶态合金催化剂.通过X射线衍射、电感耦合等离子体发射光谱、扫描电子显微镜、透射电子显微镜和选区电子衍射等技术研究了壳聚糖对Ni-B催化剂非晶性质、组成、形貌、粒径及分散度的影响.以环丁烯砜加氢制环丁砜和对氯硝基苯加氢制对氯苯胺为探针反应,考察了壳聚糖对负载型Ni-B非晶态合金催化剂催化性质的影响,讨论了壳聚糖用量及水溶性壳聚糖的相对分子质量对催化剂性质的影响.结果表明,壳聚糖介质的引入能够提高活性组分的分散度,减小活性组分的粒径,从而明显提高了催化剂的催化加氢活性.当壳聚糖在载体表面形成单层分散时催化剂活性最高.分子质量相对较低的水溶性壳聚糖有利于生成粒径小、分散性好和催化活性高的Ni-B非晶态合金催化剂.     

应用TG-FTIR技术研究黄土庙煤催化热解特性

用浸渍法制备过渡金属氧化物担载型催化剂MO_x/USY(M=Co、Mo、Co-Mo),用热重红外联用技术考察了MO_x/USY催化剂对黄土庙(HTM)煤热解失重特性和热解产物生成规律的影响。热重实验结果表明,MO_x/USY催化剂可使HTM煤热解的二次脱气条件更为温和,热解峰温分别提前14、23和9℃。动力学分析结果表明,MO_x/USY催化剂可降低HTM煤样热解的活化能。FT-IR研究表明,MO_x/USY催化剂可有效改善HTM煤热解产物的组成和分布,CoO_x/USY催化剂能显著提高HTM煤热解产物中高热值气体(CO、CH₄)和轻质芳烃以及脂肪烃类化合物的含量;MoO_x/USY催化剂没有明显改善HTM煤热解产物组成和分布;MoO_x-CoO_x/USY催化剂可促进CO、CH₄、轻质芳烃和脂肪烃类化合物的生成,却使热解产物的生成向高温区移动,说明USY负载的不同过渡金属氧化物对煤样热解行为和热解产物有较大影响。     

不同分子筛负载锰铈催化剂的低温NH_3-SCR脱硝性能

分别以β、ZSM-5和USY分子筛为载体,采用浸渍法制备了锰铈催化剂,对其低温NH_3-SCR反应性能进行了评价,并采用XRD、BET、NH_3-TPD、H_2-TPR以及XPS对催化剂进行了表征。结果表明,三种分子筛负载的锰铈催化剂均具有较好的低温NH_3-SCR反应活性,其中,Mn-Ce/USY的催化性能最好,在107℃时NOx转化率可达到90%。负载锰铈后催化剂的比表面积和孔体积均有所下降;活性组分MnOx主要以无定型态分布于催化剂表面,且在ZSM-5上检测到聚集的CeO_2。催化剂表面弱酸对低温NH3-SCR反应起主要作用,催化剂表面上活性组分的表面浓度和氧化态明显不同,较高的Mn~(4+)/Mn~(3+)原子比和吸附氧表面浓度对提高催化剂的低温NH3-SCR反应活性有利。     

Pt/Ni双金属纳米溶胶的制备及催化制氢性能

采用化学共还原法制备了聚乙烯吡咯烷酮(PVP)稳定的Pt/Ni双金属纳米溶胶.采用紫外-可见光谱(UV-Vis)、透射电子显微镜(TEM)对所合成的Pt/Ni双金属纳米溶胶进行了表征, 并系统研究了PVP用量、还原剂用量和浓度、双金属比例对该双金属纳米溶胶催化剂催化性能的影响.结果表明, 所制备的双金属纳米溶胶的平均粒径在2.0 nm左右, Pt/Ni双金属纳米溶胶的催化活性比Pt及Ni单金属纳米溶胶的高, 当Pt/Ni摩尔比为1:4时, 纳米溶胶的催化活性最高, 其活性值为16640 mol_H2·mol_Pt^-1·h^-1.所制备的Pt/Ni双金属纳米溶胶催化剂具有很好的耐久性, 5次催化实验后该催化剂仍保持较高的催化活性.该双金属纳米溶胶催化NaBH₄水解反应的活化能为48 kJ/mol.     

Sputtered nano-cobalt on H-USY zeolite for selectively converting syngas to gasoline

Selectively converting CO and H2 to gasoline product(isoparaffin and olefin) in one step still remains a great challenge. We demonstrate effective H-USY zeolite supported nano-cobalt bifunctional catalysts for this catalytic reaction, which are prepared by the novel physical sputtering process. Particles of the sputtered cobalt exist in nano-level and are well-dispersed on acid USY zeolite. Easy activation of the loaded nano-cobalt is also achieved in a low-temperature hydrogen reduction atmosphere. In the tandem catalytic reaction, the sputtered bifunctional Co/USY catalyst exhibits a much higher CO conversion and higher isoparaffin selectivity than the conventional impregnated one. Compared with H-Mor, H-Beta and other zeolites supported catalysts, H-USY zeolite supported cobalt catalyst shows the clearest promotional effect on the activity of FischerTropsch synthesis. The described synthesis herein provides a new pathway to solve the problem caused by the strong metal-support interaction(MSI) in heterogeneous catalysis.     

Reduction of 4-Nitrophenol Using Ficin Capped Gold Nanoclusters as Catalyst

Conversion of nitroarenes to aminoarenes has attracted great attention in pharmaceutical industry, agricultural production, environmental protection and chemical catalysis area. In this work, ficin capped gold nanoclusters(ficin@AuNCs) were prepared for the reduction of 4-nitrophenol to 4-aminophenol.The proposed catalyst was characterized by transmission electron microscopy,dynamic light scattering, fluorescence spectra and UV-Vis spectra. With NaBH4 as the reducing agent, the reduction reaction could carry out completely within 10 min at 25 ℃. Interestingly, the resultant catalyst exliibited size-related properties in the reduction, smaller ficin@AuNCs exhibited liigher catalytic activity. Its present pseudo-first-order rate constant was found to be 2.95×10^-3 s^-1 and the catalytic activation energy was 27.7 kJ/mol. Moreover, ficin@AuNCs-based catalyst displayed good stability, heading to 4-nitrophenol conversion of 98.5%-100.0% after six consecutive cycles. It has shown a great potential in construction of unique catalysts based on AuNCs for reduction reaction.     

Synthesis of a Novel Co-B/CTAB Catalyst via Solid-state-reaction at Room Temperature for Hydrolysis of Ammonia-borane

Cobalt-boride(Co-B) is emerging as one of the promising materials in the base-hydrolytic dehydrogenation of ammonia-borane(AB). In order to avoid the low specific area and poor catalytic capacity of Co-B catalyst caused by aggregation arising from the strong reducing property and rapid reaction condensation of sodium borohydride(NaBH₄), novel cobalt boride/cetyltrimethylammonium bromide(Co-B/CTAB) catalyst was obtained via solid-state grinding at room temperature, and the catalyst was further characterized by XRD, SEM, XPS and BET. The hydrogen generation rate(HGR) was then determined by the hydrolysis reaction of AB. The SEM images indicate that a lot of irregular folds and curled edges are formed on the sample with a maximum surface area of 145.57 m²/g, thus possibly resulting in the high hydrogen production(HGR was 10.68 L·min^-1·g^-1), which may be attributed to CTAB that provide favorable large specific surface area and abundant porous structure. Additionally, catalyst will not be affected by solvants during solid-state reaction. As a diluent, the surfactant CTAB hindered the reaction rate of sodium borohydride reduction to cobalt boride and obtained the novel catalyst with a large specific surface area.     

Production of hydrogen peroxide from carbon monoxide, water and oxygen over alumina-supported Ni catalysts

Novel amorphous Ni–B catalysts supported on alumina have been developed for the production of hydrogen peroxide from carbon monoxide, water and oxygen. The experimental investigation confirmed that the promoter/Ni ratio and the preparation conditions have a significant effect on the activity and lifetime of the catalyst. Among all the catalysts tested, the Ni–La–B/γ-Al₂O₃ catalyst with a 1:15 atomic ratio of La/Ni, dried at 120 °C, shows the best activity and lifetime for the production of hydrogen peroxide. The deactivation of the alumina-supported Ni–B amorphous catalyst was also studied. According to the characterizations of the fresh and used catalysts by SEM, XRD and XPS, no sintering of the active component and crystallization of the amorphous species were observed. However, it is water poisoning that leads to the deactivation of the catalyst. The catalyst characterization demonstrated that the active component had changed (i.e., amorphous NiO to amorphous Ni(OH)₂) and then salt was formed in the reaction conditions. Water promoted the deactivation because the surface transformation of the active Ni species was accelerated by forming Ni(OH)₂ in the presence of water. The formed Ni(OH)₂ would partially change to Ni₃(PO₄)₂.     

NiWO_4/g-C_3N_4的制备及其在离子液体中氧化脱硫性能的研究

采用水热法合成了NiWO_4纳米粒子,然后通过混合煅烧法成功地制备了负载型催化剂NiWO_4/g-C_3N_4。采用XRD、FT-IR、EDS、SEM、BET和XPS表征了NiWO_4/g-C_3N_4的形貌和结构特征。以NiWO_4/g-C_3N_4为催化剂,过氧化氢为氧化剂,1-丁基-3-甲基咪唑四氟硼酸盐离子液体([BMIM]BF4)为萃取剂。考察了催化剂的负载量,过氧化氢、离子液体和催化剂使用量,反应温度,反应时间,不同种类的含硫化合物对脱硫效果的影响。结果表明,在5 m L模拟油,0.2 m L过氧化氢,1.0 m L的[BMIM]BF4,0.03 g的NiWO_4/g-C_3N_4,反应温度为80℃,反应时间为140 min的最佳的反应条件下,脱硫率可以达到97.35%。实验表明,NiWO_4/g-C_3N_4具有很好的催化稳定性,催化剂重复使用五次后催化活性并没有明显地降低。