硝酸水热处理活性炭对其负载的Ba-Ru-K氨合成催化剂性能的影响

采用N2物理吸附、Boehm滴定、He-TPD-MS、CO化学吸附和透射电镜等手段考察了硝酸水热处理对活性炭(AC)及其负载的Ru基催化剂的孔结构、表面含氧基团、Ru分散度的影响,并评价了Ba-Ru-K/AC催化剂氨合成反应性能.结果表明,经硝酸水热处理后,AC表面含氧基团明显增多,但其孔结构变化不大.随着水热处理硝酸浓度的增加,AC表面含氧基团的数量增加,而相应催化剂的Ru分散度有所降低,Ru粒子尺寸增大.当硝酸浓度为2.0mol/L时,Ru分散度较高,且粒子尺寸(2.0nm)适宜,分散均匀,因此催化剂活性较高.在10MPa和10000h1条件下,400和375oC时,出口氨浓度分别达到17.80%和11.10%,较4.6mol/L硝酸回流处理AC负载的Ru基催化剂分别提高了16.8%和21.3%.水热处理AC的适宜条件为硝酸浓度2.0mol/L,150oC处理4h,填充度为70%.因此,通过调节水热处理时所用硝酸浓度可有效调控AC表面含氧基团的数量及其负载Ru的粒子尺寸.     

氯化钌氨作前驱体制备高活性的氨合成催化剂

以氯化钌和水合肼反应制备了新型的氧化钌氨前驱体Ru(NH3)5Cl3.透射电镜和CO化学吸附结果表明,由Ru(NH3)5Cl3前驱体制备的活性炭(AC)负载的RuN/AC催化剂中.钌纳米粒子分散度高,粒径分布均匀.与以氯化钌为前驱体制备的Ru/AC催化剂相比,RuN/AC催化剂具有更高的氨合成活性,在10 MPa和10 000 h-1条件下活性增幅超过10%.     

柠檬酸对Ru/AC氨合成催化剂结构和活性的影响

使用柠檬酸(CA)修饰石墨化活性炭(AC)和钌以改善Ru/AC催化剂中钌粒子的尺寸分布和催化剂的活性, 并通过透射电镜(TEM)、热重分析(TGA)、CO化学吸附和N2物理吸附等方法研究了柠檬酸对AC和Ru/AC催化剂织构、钌的分散度和催化剂的活性等性质的影响. 结果表明, 负载的柠檬酸优先吸附于活性炭微孔, 少量柠檬酸即可大幅度降低活性炭的比表面积, 增加活性炭表面含氧官能团的数量, 改善了钌粒子分布. 最佳负载顺序是柠檬酸和氯化钌依次负载. 在活性炭中添加适量的柠檬酸对催化剂的低温活性有显著影响. 柠檬酸处理后的Ru/AC催化剂活性最大提高幅度为21.4%.     

预处理方法对Ru/SBA-15催化丙三醇氢解反应性能的影响(英)

使用浸渍法结合不同预处理方法制备了一系列的Ru/SBA-15催化剂,并将其应用于丙三醇氢解反应中.使用N_2吸附-脱附、X射线衍射、CO化学吸附以及透射电子显微镜等方法对所制备Ru/SBA-15进行了表征.结果表明,催化剂前驱体经过空气焙烧后再经H_2还原的Ru/SBA-15催化剂上Ru的分散度较低,而直接使用H_2处理较高.同时,随着H_2还原温度提高,Ru分散度逐渐降低.保持反应活性接近时,随着Ru分散度的降低,TOF增加.表明Ru/SBA-15催化剂上丙三醇氢解是结构敏感反应.     

预处理方法对Ru/SBA-15催化丙三醇氢解反应性能的影响(英)

使用浸渍法结合不同预处理方法制备了一系列的Ru/SBA-15催化剂,并将其应用于丙三醇氢解反应中.使用N₂吸附-脱附、X射线衍射、CO化学吸附以及透射电子显微镜等方法对所制备Ru/SBA-15进行了表征.结果表明,催化剂前驱体经过空气焙烧后再经H₂还原的Ru/SBA-15催化剂上Ru的分散度较低,而直接使用H₂处理较高.同时,随着H₂还原温度提高,Ru分散度逐渐降低.保持反应活性接近时,随着Ru分散度的降低,TOF增加.表明Ru/SBA-15催化剂上丙三醇氢解是结构敏感反应.     

制备过程对 Pd-SiW12/SiO2 催化剂在乙烯选择氧化制乙酸反应中催化性能的影响

 采用不同负载顺序或制备过程制备了 Pd-SiW12/SiO2 催化剂, 考察了它们在乙烯直接氧化制乙酸反应中的催化性能. 结果表明, Pd 和 SiW12 的负载顺序与 Pd 负载后的处理条件对 Pd-SiW12/SiO2 催化剂上 Pd 的分散度影响较大, 但对催化剂表面 B 酸量影响不大, 而 Pd 分散度较高时, 相应催化剂活性较高. 将 Pd 和 SiW12 同时负载于 SiO2 上时, 催化剂表现出较高的催化乙烯直接氧化制乙酸反应活性.     

活性炭及表面性质对Ru基氨合成催化剂性能的影响

 采用N2物理吸附和He-TPD等表征手段考察了不同活性炭及其经HNO3和氧化处理后的孔结构性质及表面基团的变化,并用CO化学吸附分析了其对活性组分Ru分散度的影响. 结果表明,活性炭较发达的中孔结构可显著提高Ru的分散度. 活性炭的部分表面含氧基团是Ru的分散中心,它们的量会明显影响催化剂的Ru分散度及活性. 活性炭经HNO3处理虽然可以使含氧基团的量增加,但同时也使不稳定基团的量增加,这些不稳定基团在催化剂还原过程中分解,不利于Ru的分散. 活性炭的气相热处理可以调变其表面结构及表面基团,从而提高 Ru的分散度及催化剂活性.     

溶胶负载法制备的Au/AC催化分解低浓度臭氧

采用溶胶负载法制备了高分散的活性炭载纳米Au(Au/AC),研究了其在室温下对低浓度臭氧的催化分解性能,并用N<,2>吸附-脱附、扫描电镜、X射线光电子能谱等手段对反应前后的催化剂进行了表征.结果表明,与普通的传导加热方式相比,微波加热方式所制备的活性炭载Au颗粒的分布更均匀、尺寸更小,具有更高的催化臭氧分解性能.Au前驱体溶液pH值对Au/AC催化剂的臭氧分解性能有显著影响,以pH=8最佳.降低空速而延长臭氧与催化剂的接触时间可以提高催化剂对臭氧的分解性能.空速120000 h-1条件下.催化剂处理约1 g臭氧后,臭氧去除率降低至78.6%:而60 000 h-1条件下处理1.25 g臭氧后,臭氧的去除率仍保持在93.3%.Au/AC催化剂在分解臭氧后,表面部分C被氧化而含氧量增加,但比表面积和孔容等变化不大,主要通过负载Au颗粒本身催化分解臭氧.     

Ru助剂对Co/SiO2催化剂费托合成反应性能的影响

 考察了 Ru 助剂 (0.17%?9.96%) 对 Co/SiO2 催化剂结构及其费托合成反应性能的影响. 结果表明, Ru 助剂可降低 Co/SiO2 催化剂的还原温度, 从而提高其还原度. 光电子能谱和扩展 X 吸收射线精细结构研究表明, 即使 Ru 含量高达 9.96%, 在 Co/SiO2 催化剂焙烧过程中也未观察到 Ru 物种与 Co 物种作用形成的化合物. 还原后催化剂中 Ru 趋向于与 Co 物种紧密接触且分散在催化剂表面. H2 程序升温脱附结果表明, 随着 Ru 含量的增加, 位于反应温度附近的 H2 脱附峰面积增加, 即此时催化剂吸附 H2 能力提高, 因此反应活性单调增加, 但存在最佳 Ru 含量, 此时 C5+选择性最高.     

贵金属对 NM/WO3-ZrO2 (NM = Ru, Rh 和 Pd) 催化乙烯直接氧化制乙酸反应的影响

 研究了负载 Ru, Rh 和 Pd 的 WO3-ZrO2 催化剂在乙烯直接氧化制乙酸反应中的催化性能. 结果显示, 负载的贵金属对催化剂的催化性能有非常重要的影响. Rh/WO3-ZrO2 催化剂具有最高的乙烯转化率, 而 Ru/WO3-ZrO2 催化剂对反应几乎没有活性. H2 化学吸附结果显示, 高的催化性能来源于高的金属分散度. Pd/WO3-ZrO2 催化剂显示了最高的乙酸选择性 (75%), 而其它两个催化剂的乙酸选择性都非常低 (~10%). 程序升温氧化和程序升温还原结果显示, 贵金属–O 键的键强对产物的选择性具有重要的影响. 弱的贵金属–O 键可以通过将氧插入到乙烯和/或乙醛中而有利于乙酸的生成, 而强的贵金属–O 键会导致乙烯完全氧化为 COx.     

Properties of anodic RuNiO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>(OH)<Subscript><Emphasis Type="Italic">y</Emphasis></Subscript> catalysts synthesized on carbon supports with various dispersion degree

A number of catalysts of the (Ru-Ni)/C system is synthesized and studied for application in anodes of alkaline ethanol-air fuel cells. The carbon supports used are carbon blacks with different specific surface area and graphite powders. The X-ray photoelectron spectroscopy technique allowed detecting on the catalyst surface metallic ruthenium and nickel in the form of Ni(OH)2 hydroxide and possibly oxyhydroxide NiOOH. It is shown that the catalyst activity in the reaction of ethanol electrochemical oxidation grows at an increase in the specific surface area of the carbon support. The method of carbon monoxide oxidative desorption was used to determine the values of the specific surface area of the catalyst metallic phase. It is shown that at an increase in the relative ruthenium content from (1Ru3Ni)/C to Ru/C, the specific catalytic activity in the catalysts of the (Ru-Ni)/C system reaches the maximum value near the composition of (2Ru1Ni)/C. It is shown that the found optimum catalyst composition is independent of the carbon support dispersion degree. Activity in ethanol electrooxidation of the (2Ru1Ni)/C catalyst supported on the Ketjenblack EC-600 carbon black is 18 ± 3 A/g of the catalyst (>120 A/g of Ru) at 40°C and potential E = 0.5 V in the 2MKOH + 1 M C₂H₅OH electrolyte.     

载体对负载型Ni-B催化剂催化2-乙基蒽醌加氢制H2O2反应性能的影响

采用还原剂浸渍法将Ni-B非晶态合金负载到SiO2,γ-Al2O3和活性炭(AC)上,以2-乙基蒽醌选择加氧制H2O2为探针反应,系统研究了载体对Ni-B非晶态合金催化剂结构、热稳定性和催化性能的影响.结果表明,将Ni-B负载到载体上后,其晶化温度显著提高,各催化剂热稳定性依次为Ni-B/AC＞Ni-B/SiO2＞Ni...     

The Preparation and Characterization of Highly Dispersed PdO over Alumina for Low‐temperature Combustion of Methane

PdO/Al₂O₃ catalysts prepared by glow discharge plasma treatment followed by thermal calcination show a much higher dispersion and a better catalytic activity for methane combustion at relatively low temperatures. The dispersion of palladium active species by such plasma prepared catalysts is 29.7%, 5.4 times higher than that of conventional catalysts. XPS analysis indicates that a surface enrichment of Pd active species (PdO) has been achieved after plasma treatment. The surface atomic composition of PdO of plasma prepared catalysts reaches 10.5%. XRD characterization also confirms a wellcrystallized PdO phase present on the plasma prepared catalyst. The lightoff temperature of the plasma prepared catalyst is 370°C, 50°C lower than that obtained from the conventional catalyst.     

Effect of activated graphite nanofibers on electrochemical activities of Pt–Ru nanoparticles for fuel cells

In this work, graphite nanofibers (GNFs) were chemically activated for high specific surface area, small pore diameter, and high oxygen-containing groups with different KOH/GNFs ratios and used as carbon supports of Pt–Ru nanoparticles for fuel cells. As a result, the oxygen functional groups and specific surface area of carbon supports were increased with increasing the ratios of KOH/GNFs up to 4:1, while the average of Pt–Ru nanoparticle size was decreased owing to the improvement of dispersibility of the Pt–Ru/K–GNFs catalysts. The electrochemical activity of the Pt–Ru/K–GNFs catalysts was improved by the larger available active surface area due to the increase of oxygen functional groups and specific surface area. Therefore, it was found that chemical activation using KOH could influence the surface characteristic of carbon supports, resulting in enhanced electrochemical activity of the Pt–Ru/K–GNFs catalysts of fuel cells.     

Supported Ru catalysts prepared by two sonication-assisted methods for preferential oxidation of CO in H2

The preferential oxidation (PROX) of CO in the presence of H(2) is an important step in the production of pure H(2) for industrial applications. In this report, two sonochemical methods (S1 and S2) were used to prepare highly dispersed Ru catalysts supported on mesoporous TiO(2) (TiO(2)(MSP)) for the PROX reaction, in which a reaction gas mixture containing 1% CO + 1% O(2) + 18% CO(2) + 78% H(2) was used. The supported Ru catalysts performed better than the supported Au and Pt catalysts, and the S1 and S2 methods are superior to the impregnation method. The Ru/TiO(2)(MSP) catalysts were active for the PROX reaction below 200 °C and good for the methanation reactions of CO and CO(2) above 200 °C. The presence of residual chlorine in the catalysts severely suppressed their PROX reaction activity, and a higher dispersion of Ru particles led to better catalytic performances. The addition of Au in the Ru/TiO(2)(MSP) catalyst also caused a poorer catalytic activity for both the PROX and the methanation reactions. TPR results showed that in the active catalysts prepared by the S1 and S2 methods, the well dispersed Ru particles, after calcination in air, had a stronger interaction with the support than those in the catalyst prepared by the impregnation method and in the Au-Ru/TiO(2)(MSP) catalyst. In situ CO absorption experiments performed with the diffusion reflectance Fourier transform infra red (DRIFT) method showed that the bridged adsorbed CO species on isolated Ru(0) sites correlated with the catalytic performances, indicating that these isolated Ru(0) sites are the most active sites of the Ru/TiO(2)(MSP) catalysts in the PROX reaction.     

不同方法制备的Cu/HZSM-5催化剂上NO的催化分解反应

采用离子交换法、固相分散法和微波固相法等不同方法制备了Cu/HZSM-5催化剂,以BET、XRD和XPS等手段对催化剂样品进行了表征。结果表明,不同方法制备的Cu/HZSM-5催化剂上Cu物种的落位分布状态不同,离子交换法制备的催化剂Cu物种更多地落位于分子筛孔道内,微波固相法和固相分散法制备的催化剂Cu物种较多地落位分布在分子筛外表面。固相分散法制备的样品未能使铜物种完全分散于分子筛表面,在13.1°、16.8°、35.5°和38.0°等处仍存在CuO的晶相衍射峰。催化分解NO反应的活性考察结果表明,用微波固相法制备的催化剂催化分解NO的活性及稳定性明显超过另两种方法所制备的催化剂,在无氧条件下NO最初转化率高达89.2%,经反应25h后,转化率仍维持在70%以上;在富氧气氛下催化分解NO活性降低速率低于由离子交换法制备的催化剂。结合表征结果可以得出,落位于分子筛外表面以离子交换态形式存在的Cu物种对催化分解NO反应更为有利,而且催化稳定性更好。     

氮掺杂碳纳米管负载的Ru和Pd催化剂上异丙醇的转化(英文)

Ru and Pd (2 wt%) loaded on pure and on Ndoped carbon nanotubes (NCNTs) were prepared and tested using the isopropyl alcohol decomposition reaction as probe reaction. The presence of nitrogen functionalities (pyridinic, pyrrolic, and quaternary nitrogen) on the nitrogen doped support induced a higher metal dispersion: Pd/NCNT (1.8 nm) Pd/CNT (4.9 nm), and Ru/NCNT (2.4 nm) Ru/CNT (3.0 nm). The catalytic activity of the supports was determined first. Isopropyl alcohol conversion produces acetone on CNTs while on NCNTs it led to both dehydration and dehydrogenation products. At 210 °C and in the presence of air, the isopropyl alcohol conversion was higher on the NCNTs (25%) than on the CNTs (11%). The Pd loaded catalysts were more active and more selective than the Ru ones. At 115 °C, the Pd catalysts were 100% selective towards acetone for a conversion of 100%, whereas the Ru catalysts led to dehydration and dehydrogenation products. The nitrogen doping induced the appearance of redox properties when oxygen is present in the reaction mixture.     

不同活性炭上Pt催化剂的分散性及其在甲基环己烷脱氢反应中的催化性能

在不同方法处理的活性炭上采用传统浸渍方法制备了负载Pt催化剂,并考察了其在甲基环己烷脱氢反应中的催化性能.对炭载体的氮吸附和程序升温脱附的表征结果表明,活性炭经过硝酸氧化处理和氢气高温处理后,活性炭的孔结构基本不变,但表面含氧官能团的数量和种类发生了变化.这些不同的表面基团直接影响了Pt粒子在载体上的分散度,进而使催化剂在反应中表现出不同的活性.