具有空心结构的Ni/SiO_2催化剂上间二硝基苯加氢制间苯二胺

采用水热法一步合成了Ni3Si2O5(OH)4空心微球。在823K、H2气氛下还原,制备了具有空心结构的Ni/SiO2催化剂,采用X射线衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、N2吸附-脱附对催化剂进行了表征。将该催化剂应用于间二硝基苯加氢制备间苯二胺的反应中,考察了催化剂结构、反应温度、反应时间、反应压力对反应的影响。在最优条件下,间二硝基苯的转化率为100%,生成间苯二胺的选择性约为94%。     

用于甲烷二氧化碳重整反应的Ni基催化剂的研究进展

对用于甲烷二氧化碳重整反应的Ni基催化剂的研究进展进行了概述,详细分析了Ni金属结构形态、载体、助剂及制备方法等方面对Ni基催化剂活性、稳定性及抗积碳性能的影响。     

用于甲烷蒸汽重整的Cu／ZnO-CNTs纳米催化剂的制备及活性

用化学还原法和浸渍法制备了一种新型的Cu／ZnO-CNTs纳米催化剂，将其用于甲醇蒸汽重整反应。其中碳纳米管（carbon nano-bube，CNT）在用作载体之前，必须进行预处理，在60℃的硝酸和硫磺酸中浸泡24h，从而给CNT表面制造缺陷；同时还通过加入适量的乙醇提高CNT的亲水性。     

Ni基甲烷二氧化碳重整催化剂研究进展

由于甲烷二氧化碳重整将两种温室气体甲烷和二氧化碳转化为可利用的合成气,因此近二十年以来引起了越来越多研究者的关注。其中,Ni基催化剂由于其较高的活性和较低的成本得到了广泛的研究。本文将甲烷二氧化碳重整Ni基催化剂分为负载型和非负载型两大类分别综述了它们的研究进展。针对反应条件下的Ni基催化剂因积炭和烧结引起的失活问题,本文介绍了引起这两个问题的原因,并概括了抑制失活并提升Ni基催化剂活性和稳定性的5条途经,包括选择性钝化活性金属、增强Ni颗粒分散性、控制催化剂的酸碱性、减小Ni颗粒的尺寸以及提高Ni颗粒稳定性。最后指出,设计和制备颗粒小而且稳定的催化剂是同时解决催化剂积炭和烧结两大问题的关键。     

Ni/γ-Al_2O_3催化剂上甲烷水蒸气重整制合成气

采用固定床装置,考察了负载型Ni系列催化剂及反应条件对Ni/γ-Al2O3催化剂的甲烷水蒸气重整反应的影响,并利用XRD和TPR技术对催化剂样品进行表征。结果表明,在空速1 800 h-1,n(H2O)∶n(CH4)∶n(N2)=2.86∶1∶3.28,反应温度700℃的条件下,催化剂Ni含量在9%时反应性能最佳,可得到94.3%的CH4转化率和64.9%的CO选择性。     

甲烷二氧化碳重整用Ni/AC催化剂的阈值效应研究

为研究活性炭负载Ni(Ni/AC)基催化剂在甲烷二氧化碳重整反应中的阈值效应,采用N2吸附(BET)和X射线衍射(XRD)测试技术对活性炭负载Ni(Ni/AC)基催化剂进行分析,分别探讨了浸渍溶剂和负载量对催化剂表面结构、Ni分散状态和分散阈值的影响。结果表明,采用丙酮作为溶剂制备的催化剂比纯水在活性炭载体表面更有利镍的分散,提高了活性组分有效面积,并具有更高的分散阈值。对比密置单层排列模型计算值认为Ni在AC表面呈非密置单层或亚单层分散。Ni/AC催化重整甲烷二氧化碳实验结果显示,丙酮作为浸渍溶剂比纯水制备的催化剂表现出更好的催化活性,负载型Ni/AC催化剂在甲烷二氧化碳重整反应中存在显著的阈值效应。     

纳米SiO_2负载镍催化剂催化环烯烃聚合北大核心

利用硅烷偶联剂将乙酰丙酮二氯化镍连结在纳米SiO_2表面,制备了纳米SiO_2负载的镍催化剂,并以三五氟苯基硼为助催化剂,催化降冰片烯的加成聚合,原位制备了纳米SiO_2杂化的聚降冰片烯,观察了杂化材料的形貌及纳米SiO_2的分布情况,并研究了其力学性能。结果表明:通过改变聚合温度、n(B)∶n(Ni)、催化剂与降冰片烯投料比等,可以实现对聚合活性以及所得聚合物性能的调控;当聚合温度为60℃,n(B)∶n(Ni)为20时,聚合活性最高可达0.36 kg/(mmol·h);当降冰片烯与催化剂的摩尔比为2 000∶1时,所制纳米SiO_2杂化的聚降冰片烯力学性能最佳。     

烧绿石型Ni基催化剂的制备及甲烷重整性能研究

采用溶胶凝胶法制备了不同Ca含量改性的Ni-La₂Zr₂O₇烧绿石型催化剂,并利用H₂-TPR、XRD和TG等技术对催化剂的结构和性质进行了表征。同时考察了不同Ca含量改性的Ni-La₂Zr₂O₇催化剂的甲烷二氧化碳重整催化性能。研究表明,掺杂适量的Ca并不会显著破坏载体的烧绿石结构。添加适量的Ca(4%)增强了Ni和载体之间的相互作用,促进了Ni的分散,提高了烧绿石型镍基催化剂的甲烷二氧化碳催化性能,同时抑制了催化剂表面积碳的形成。     

甲烷重整制合成气用催化剂的研究进展

甲烷重整是制取合成气的重要方法之一,催化剂是重整工艺中的重要组成部分。综合国内外的研究现状,详细论述了甲烷重整反应的几种不同的途径,并针对不同的途径介绍了其反应机理以及催化剂的组成。     

Carbon Dioxide Reforming of Methane Over Nanocomposite Ni/ZrO2 Catalysts

A systematic study of the size effect of zirconia nanocrystals on nickel-catalyzed reforming of methane with CO₂ shows that extremely stable Ni/ZrO₂ catalysts are obtainable by hydrogen reduction of impregnated nickel nitrate on zirconia particles with sizes less than 25 nm. The same preparation method with larger particles of zirconia results in catalyst samples that deactivate rapidly in the reforming reaction. Comprehensive characterization with XRD, TPR/TPD, and TEM shows that the stable Ni/ZrO₂ catalysts are better described as nanocomposites of size comparable to Ni metal (9-15 nm) and zirconia (7-25 nm) nanoparticles. The high percentage of the Ni-zirconia boundary or perimeter in the nanocomposite catalysts is believed to be crucial for the extremely stable catalytic activity.     

镍盐前驱体对Ni/SBA-15催化剂上甲烷干重整反应性能的影响

研究了不同镍盐前驱体(硝酸镍、乙酸镍和氯化镍)制备的Ni/SBA-15催化剂对甲烷干重整反应催化性能的影响。与硝酸镍和氯化镍相比,以乙酸镍为前驱体制备的催化剂在不同反应温度下具有优异的催化活性,在700℃下,经过20 h连续的稳定性测试,催化剂仍表现出良好的稳定性和选择性。利用N_2吸附-脱附、XRD、XPS、H_2-TPR和TG对催化剂结构、表面物种和还原性等进行分析。结果表明,乙酸镍制备的Ni/SBA-15催化剂具有较低的NiO结晶度以及良好的分散度、优越的氧化还原性能和抗积碳性能。此外,活性组分Ni与载体SBA-15之间的相互作用有利于其良好的催化活性。     

等离子体制备稀土金属掺杂甲烷干气重整Ni/Mg/Al催化剂研究

采用冷等离子体炬技术制备了以水滑石为前驱体的Ni/Mg/Al催化剂,考察了La和Ce助剂的添加对催化剂结构及其对CH4和CO2重整催化性能的影响。利用XRD、BET、XPS及TG对催化剂进行了表征和性能测试。结果表明：冷等离子体炬能快速分解Ni/Mg/Al水滑石前驱体,生成具有介孔特性的水镁石相Mg(Ni,Al)O固溶体,并生成Ni0晶粒。在温度700℃,空速30000mL/(h·gcat), V（CH4）：V（CO2）=4：6的条件下,CH4和CO2的转化率分别为76%和61.8%。助剂Ce的添加增加了晶格氧,促进催化剂表面碳物种的消除,CH4和CO2的转化率分别提高了5%和7%。La的加入,抑制了Ni晶粒的团聚,增加了Ni的分散度,与未添加La的催化剂相比非活性碳的生成量减少70%,表现出良好的抗积炭性能。     

Small Amounts of Rh-Promoted Ni Catalysts for Methane Reforming with CO2

Small amounts of Rh-promoted Ni/-Al₂O₃ catalysts possessed higher activity than pure Ni/-Al₂O₃, Rh-Al₂O₃ catalysts and exhibited excellent coke resistance ability in methane reforming with CO₂. XRD, H₂-TPR, CO₂-TPD and coking reaction (via CH₄ temperature-programmed decomposition) indicated that Rh improved the dispersion of Ni, retarded the sintering of Ni and increased the activation of CO₂ and CH₄ on the surface of catalyst.     

Ni–Fe Catalysts Based on Perovskite-type Oxides for Dry Reforming of Methane to Syngas

LaNi_(1−x)Fe_xO₃ (x=0, 0.2, 0.4 and 0.7) perovskite-type catalysts were modified by the partial substitution of nickel by iron, aiming to increase the stability and resistance to carbon deposition during the methane dry reforming reaction. The results showed that a suitable combination of precipitation and calcination steps could result in oxides with the desired structure and with improved properties from the point of view of heterogeneous catalysis. The partial substitution of Ni by Fe in the perovskite structure resulted in decreasing rates of conversion of both reactants. However, the stability of the catalyst during the reaction was highly increased. These substituted catalysts were shown to be stable and the LaNi_0.8Fe_0.2O₃ catalyst, calcined at 800 °C for 5 h, was the most active in the reaction conditions.     

Reforming of methane and coalbed methane over nanocomposite Ni/ZrO2 catalyst

Nanocomposite Ni/ZrO₂-AN catalyst consisting of comparably sized Ni metal and ZrO₂ nanoparticles is studied in comparison with zirconia- and alumina-supported Ni catalysts (Ni/ZrO₂-CP and commercial Ni/Al₂O₃-C) for steam reforming of methane (SRM) and for combined steam and CO₂ reforming of methane (CSCRM). The reactions are performed under atmospheric pressure with stoichiometric amounts of H₂O and CH₄ or (H₂O + CO₂) and CH₄ at 1073 K. Under a wide range of methane space velocity (gas hourly space velocity of methane GHSV_CH4 = 12,000–96,000 ml/(h g_cat.), the nanocomposite Ni/ZrO₂-AN catalyst always shows higher activity and stability for both SRM and CSCRM reactions. The two supported Ni catalysts (Ni/ZrO₂-CP and Ni/Al₂O₃-C) exhibit fairly stable catalysis under low GHSV_CH4 but they are easily deactivated under high GHSV_CH4 and become completely inactive when they are reacted for ca.100 h at GHSV_CH4 = 48,000 ml/(h g_cat.). The CSCRM reaction is carried out with different H₂O/CO₂ ratios in the reaction feed while keeping the molar ratio (H₂O + CO₂)/CH₄ = 1.0, the results prove that the nanocomposite Ni/ZrO₂-AN catalyst can be highly promising in enabling a catalytic technology for the production of syngas with flexible H₂/CO ratios (ca. H₂/CO = 1.0–3.0) to meet the requirements of various downstream chemical syntheses.     

Partial Oxidation and Dry Reforming of Methane Over Ca/Ni/K(Na) Catalysts

Partial oxidation and dry reforming of methane to synthesis gas over Ca/Ni/K(Na) catalysts have been studied. Effects of temperature, pressure, and oxygen/methane ratios on catalytic activity, selectivity, and carbon formation have been determined. Also reforming of ¹³CH₄ in the presence of CO₂ and Temperature-Programmed Oxidation (TPO) of deposited carbon after the reaction indicated that both methane and CO₂ contribute to carbon formation. The TPO of deposited carbon on Ca/Ni/K catalyst showed that the catalyst consumed a significant amount of oxygen, only a fraction of which was consumed by carbon species on the surface, indicating that the surface oxygen plays a significant role in oxidizing and removing carbon species from the catalyst surfaces     

Steam and Dry Reforming Processes Coupled with Partial Oxidation of Methane for CO2 Emission Reduction

CO₂ is thought to contribute to global climate change. A novel integrated process of steam methane reforming (SMR) and dry methane reforming (DMR) coupled to partial oxidation of methane (POX) has been developed that utilizes the compensating heat effects of DMR and POX and recycles a large amount of CO₂ to the DMR+POX section. Both SMR and the integrated process were simulated using Aspen Plus and were optimized to operate under their respective optimum operating conditions. Modified mitigation cost (MMC) was implemented as the evaluation method. The results demonstrate that the combined process is more efficient than the SMR process due to its reutilization of CO₂ and lower requirement of raw materials.     

Regeneration of Ni/SiO2 poisoned with carbon disulfide

The poisoning effect of carbon disulfide on a model nickel/silica catalyst and the regenerating role of both pure hydrogen and 2-butyne + hydrogen are reported. The treatments induce the elimination of sulfur and promote a recovery of the catalytic activity; irreversible adsorbed sulfur still remains on the catalyst.