Effects of sol-gel method and lanthanum addition on catalytic performances of nickel-based catalysts for methane reforming with carbon dioxide

基于镍的催化剂被大音阶的第五音胶化方法准备并且为与 CO2 改过的 CH4 使用了。催化剂的特定的表面区域，催化活动，解吸附作用，和减小表演上的大音阶的第五音胶化方法的效果与赌注， TPR，和 TPD 被调查。与受精方法准备的催化剂相比，结果显示大音阶的第五音胶化方法准备的催化剂有更大的特定的表面区域，显示出更高催化的活动并且展出完美的解吸附作用和减小表演。另外，增加 La 的修正效果被学习，并且由 5wt .%Ni-0.75wt.%La 组成的 0.75NLBT 催化剂是最佳的，这被发现。

Methane Decomposition into Carbon Fibers over Coprecipitated Nickel-Based Catalysts

Decomposition of methane in the presence of coprecipitated nickel-basedcatalysts to produce carbon fibers was investigated. The reaction was studied in the temperaturerange of 773 K to 1073 K. At 1023 K, the catalytic activities of three catalysts kept high at theinitial period and then decreased with the reaction time. The lifetimes of Ni-Cu-Al and Ni-La-Alcatalysts are longer than that of Ni-Al catalyst. With three catalysts, the yield of carbon fiberswas very low at 773 K. The yield of carbon fibers for Ni-La-Al catalyst was more than those forNi-Al and Ni-Cu-Al catalysts. For Ni-La-Al catalyst, the elevation of temperature from 873 K up to1073 K led gradually to an increase in the yield of carbon fibers. XRD studies on the Ni-La-Alcatalyst indicate that La_2NiO_4 was formed. The formation of La_2NiO_4 is responsible for theincrease in the catalytic lifetime and the yield of carbon fibers synthesized on Ni-La-Al at773-1073 K. Carbon fibers synthesized on Ni-Al catalyst are thin, long carbon nanotubes. There arebamboo-shaped carbon fibers synthesized on Ni-Cu-Al catalyst. Carbon fibers synthesized on Ni-La-Alcatalyst have large hollow core, thin wall and good graphitization.

Glow Discharge Plasma-Assisted Preparation of Nickel-Based Catalyst for Carbon Dioxide Reforming of Methane

一个帮助血浆的方法被采用准备 Ni/γ-Al 2 为甲烷反应改过的二氧化碳的 O 3 催化剂。新奇催化剂常规锻烧催化剂比那些拥有了更高的活动和更好的焦炭抑制性能。完成一样的 CH 4 变换，常规催化剂需要更高的反应温度，比 N 2 的高的大约 50 ° C 对待血浆的催化剂。在评估测试以后，新奇催化剂的释放率为常规催化剂是 1.7% ，与 15.2% 相比。与锻烧的催化剂，一条更小的平均毛孔直径和一个更高特定的表面区域的描述结果不同为对待血浆的催化剂被获得。减小山峰温度和区域的变化显示催化剂 reducibility 被血浆帮助支持。镍的分散显著地也被改进，它对在催化剂表面上控制金属原子的整体尺寸有用。氧化铝的表面性质上的帮助血浆的准备的修正效果支持了催化剂被推测说明吸收公司 2 的集中增加。公司 2 吸附的改进对碳形成的抑制慈悲。在血浆上扔的焦炭数量对待催化剂在常规催化剂上是比那小得多的。

高分散Ni/Al_(2)O_(3)-CeO_(2)催化剂的制备及其甲烷干重整性能研究

以离子交换逆负载法合成了以氧化铝和氧化铈为载体的高分散镍基催化剂,通过溶度积的(Ksp)驱动将Ni负载在氧化物载体上,得到了用于甲烷干重整的高分散催化剂.采用XRD、TEM、N_(2)物理吸附-脱附等表征手段表征了催化剂的物理化学性质,使用固定床反应器评价其催化性能,研究了催化剂中CeO_(2)含量对甲烷干重整性能的影响.结果表明:在低CeO_(2)含量时(Ce质量分数为3.4%),催化剂具有较高活性和稳定性,产物H_(2)/CO比约等于1,反应后催化剂活性金属轻微烧结,积碳最少.

Autothermal Reforming of Methane over Ni Catalysts Supported on CuO-ZrO_2-CeO_2-Al_2O_3

Ni catalysts supported on various mixed oxides of Al2O3 with rare earth oxide and transitional metal oxides were synthesized. The studies focused on the measurement of the autothermal reforming of methane to hydrogen over Ni catalysts supported on the mixed oxide ZrxCe30-xAl70Oδ （x-=5, 10, 15）. The catalytic performance of Ni/Zr10Ce20Al70Oδ was better than that of other catalysts. XRD results showed that the addition of Zr to Ni/Ce30Al70Oδ prevented the formation of NiAl2O4 and facilitated the dispersion of NiO. Effects of CuO addition to Zr10Ce20Al70Oδ were also investigated. The activity of Ni catalyst supported on CuO-ZrO2-CeO2-Al2O3 was somewhat affected and the Ni/Cu5Zr10Ce20Al65Oδ showed the best catalytic performance with the highest CH4 conversion, yield of H2, selectivity for H2 and H2/CO production ratio in operation temperatures ranging from 650 to 750 ℃.

介质阻挡放电等离子制备5Ni-5La/SiO_(2)催化剂及其甲烷干重整反应催化性能

利用介质阻挡放电等离子体法制备了5Ni-5La/SiO_(2)催化剂,并用于甲烷干重整反应.在常压,700℃,空速为4.8×10^(4)mL·g^(‒1)·h^(‒1)时,等离子体法所制催化剂催化甲烷干重整反应的CH_(4)和CO_(2)的转化率分别为81.2%和88.4%,且在30 h内保持稳定;而传统催化剂的CH4和CO_(2)初始转化率分别为81%和88.4%,30 h后下降到58.8%和68.6%.研究结果表明,介质阻挡放电等离子体法制备的催化剂具有更高的分散性和更强的金属与La_(2)O_(3)的相互作用.等离子体处理增加了Ni周围的电子密度,增强了CO_(2)在催化剂表面的吸附能力和活化能力,促进了HCOO^(‒)中间体的生成,有利于反应正向进行.

Steam reforming of acetic acid over Ni-Ba/Al2O3 catalysts:Impacts of barium addition on coking behaviors and formation of reaction intermediates

The influence of barium addition to a Ni/Al2O3 catalyst on the reaction intermediates formed,the activity,resistance of the catalyst to coking,and properties of the coke formed after acetic acid steam reforming were investigated in this study.The results showed the drastic effects of barium addition on the physicochemical properties and performances of the catalyst.The solid-phase reaction between alumina and BaO formed BaAl2O4,which re-constructed the alumina structure,resulting in a decrease in the specific surface area and an increase in the resistance of metallic Ni to sintering.The addition of barium was also beneficial for enhancing the catalytic activity,resulting from the changed catalytic reaction network.The in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study of the acetic acid steam reforming indicated that barium could effectively suppress the accumulation of the reaction intermediates of carbonyl,formate,and C=C functional groups on the catalyst surface,attributed to its relatively high ability to cause the gasification of these species.In addition,coking was considerably more significant over the Ba-Ni/Al2O3 catalyst.Moreover,the Ba-Ni/Al2O3 catalyst was more stable than the Ni/Al2O3catalyst,owing to the distinct forms of coke formed (carbon nanotube form over the Ba-Ni/Al2O3 catalyst,and the amorphous form over the Ni/Al2O3 catalyst).

Synthesis and Crystal Structure of a New Nickel(II) Complex with Unsymmetric Quadridentate Schiff Base Containing Oxime

The title complex, C18H15N3NiO3, has been prepared and characterized by X-ray diffraction analysis. It crystallizes in the monoclinic system, space group Cc with a = 10.939(2), b = 22.909(5), c = 6.907(1) ?, β = 116.75(3)°, V = 1545.7(5) ?, Z = 4, Mr = 380.04, F(000) = 784, Dc = 1.633 g/cm3 and μ(MoKα) = 1.279 mm–1. The structure was refined to R = 0.0472 and wR = 0.0893 for 2571 observed reflections with I > 2σ(I). The absolute structure Flack parameter X is 0.01(2). In this crystal structure, strong face-to-face π-π stacking interactions between adjacent molecules lead to a one-dimensional chain structure.

Effect of CeO_2 and CaO Promoters on Ignition Performance for Partial Oxidation of Methane over Ni/MgO-Al_2O_3 Catalyst

The effect of CeO2 and CaO promoters on the ignition performance over Ni/MgO-Al2O3 catalyst for the partial oxidation of methane （POM） to synthesis gas was investigated. It was found that the POM reaction could not be ignited over lwt%Ni/MgO-Al2O3 catalyst without the promoters in the temperature range from 773 K to 1073 K. CeO2 and CaO promoters enhanced the ignition performance and the POM reactivity of lwt%Ni/MgO-Al2O3 catalyst remarkably. Moreover, the improving effect became greater with the increase of the promoter content under the investigated reactiorrconditions. The modification effects of CeO2 and CaO promoters were closely related to the concentration and reducibility of the surface and bulk oxygen species.

Improved catalytic performance of Ni catalysts for steam methane reforming in a micro-channel reactor

Milliseconds process to produce hydrogen by steam methane reforming （SMR） reaction, based on Ni catalyst rather than noble catalyst such as Pd, Rh or Ru, in micro-channel reactors has been paid more and more attentions in recent years. This work aimed to further improve the catalytic performance of nickel-based catalyst by the introduction of additives, i.e., MgO and FeO, prepared by impregnation method on the micro-channels made of metal-ceramic complex substrate. The prepared catalysts were tested in the same micro-channel reactor by switching the catalyst plates. The results showed that among the tested catalysts Ni-Mg catalyst had the highest activity, especially under harsh conditions, i.e., at high space velocity and/or low reaction temperature. Moreover, the catalyst activity and selectivity were stable during the 12 h on stream test even when the ratio of steam to carbon （SIC） was as low as 1.0. The addition of MgO promoted the active Ni species to have a good dispersion on the substrate, leading to a better catalytic performance for SMR reaction.

Ethanol steam reforming over Ni-Cu/Al_2O_3-M_yO_z (M = Si, La, Mg,and Zn) catalysts

Ni-based catalysts doped with copper additives were studied on their role in ethanol steam reforming reaction. The effects of Cu content, support species involving Al2O3-SIO2, Al2O3-MgO, Al2O3-ZnO, and Al2O3-La2O3, on the catalytic performance were studied. Characterizations by TPR, XRD, NH3-TPD, XPS, and TGA indicated that catalysts 30Ni5Cu/Al2O3-MgO and 30Ni5Cu/Al2O3-ZnO have much higher H2 selectivity than 30Ni5Cu/Al2O3-SiO2, as well as good coke resistance. H2 selectivity for 30Ni5Cu/Al2O3-MgO catalyst was 73.3% at 450 ℃ and increased to 94.0% at 600℃, whereas for 30Ni5Cu/Al2O3-ZnO catalyst, the H2 selectivity was 63.6% at 450 ℃ and 95.2% at 600℃. TheseAl2O3-MgO and Al2O3-ZnO supported Ni-Cu bimetallic catalysts may have important applications in the production of hydrogen by ethanol steam reforming reactions.

Ultralow-weight loading Ni catalyst supported on two-dimensional vermiculite for carbon monoxide methanation

Nickel-based catalysts represent the most commonly used systems for CO methanation.We have successfully prepared a Ni catalyst system supported on two-dimensional plasma-treated vermiculite(2D-PVMT)with a very low Ni loading(0.5 wt%).The catalyst precursor was subjected to heat treatment via either conventional heat treatment(CHT)or the plasma irradiation method(PIM).The as-obtained CHT-Ni/PVMT and PIM-Ni/PVMT catalysts were characterized with scanning electron microscopy(SEM),energy dispersive X-ray(EDX),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),inductively coupled plasma-atomic emission spectroscopy(ICP-AES)and high-angle annular dark field scanning transmission electron microscopy(HAADF-STEM).Additionally,CHT-NiO/PVMT and PIM-NiO/PVMT catalysts were characterized with hydrogen temperature programmed reduction(H_2-TPR).Compared with CHT-Ni/PVMT,PIM-Ni/PVMT exhibited superior catalytic performance.The plasma treated catalyst PIM-Ni/PVMT achieved a CO conversion of93.5%and a turnover frequency(TOF)of 0.8537 s^(-1),at a temperature of 450°C,a gas hourly space velocity of 6000 ml·g^(-1)·h^(-1),a synthesis gas flow rate of 65 ml·min^(-1),and a pressure of 1.5 MPa.Plasma irradiation may provide a successful strategy for the preparation of catalysts with very low metal loadings which exhibit excellent properties.

Ni/γ-Al_(2)O_(3)/Monolith催化剂的制备及其甲烷自热重整性能

以陶瓷堇青石为载体、拟薄水铝石为涂层,采用分步涂覆法制备了Ni/γ-Al_(2)O_(3)/Monolith催化剂,利用N2吸附-脱附,H_(2)-TPR,XRD,SEM等方法对催化剂进行表征,研究了催化剂焙烧温度、Ni负载量及气时空速对催化剂催化甲烷自热重整活性的影响,并考察了催化剂的稳定性。实验结果表明,经酸处理后的堇青石比表面积从0.3 m^(2)/g增大到145.1 m^(2)/g,孔体积增大到原来的35倍;负载γ-Al_(2)O_(3)涂层后,孔体积继续增大,使更多的活性组分均匀负载到堇青石上。在焙烧温度为600℃条件下,Ni负载量为20%(w)的催化剂催化效果最佳;在反应温度750℃下能够承受50000 h^(-1)的气时空速,甲烷转化率达99%以上,且具有较好的稳定性。

Kinetics modeling for the mixed reforming of methane over Ni-CeO_2/MgAl_2O_4 catalyst

Kinetics model was developed for the mixed （steam and dry） reforming of methane, which is useful for the control of H2/CO ratio. The equilibrium constants of reaction rate were determined using the experimental equilibrium data at different reaction temperatures, while the forward reaction rate constants were estimated using the experimental data under non-equilibrium （high inert fraction and high space velocity） conditions. The comparison between calculated and experimental data clearly showed that the developed model described satisfactorily, and further analysis using the parametric sensitivity determined the wall temperature and CO2 fraction in the feed gas as effective parameters for the manipulation of CH4 conversion and H2/CO ratio of synthesis gas under the equilibrium condition. Meanwhile, the inert fraction, rather than the residence time, was selected as additional parameter under non-equilibrium condition.

SiO_(2)-镍铁基复合析氧催化剂研制

近年来,电催化制氢析氧反应在清洁能源生产和高效储能方面倍受关注。镍铁基化合物资源丰富,价格低廉,具有优异的催化性能,被广泛用作电解水OER催化剂。为提高镍铁基催化剂的活性和稳定性,以泡沫镍金属片作为导电基底材料,用水热合成的方法在其表面原位合成镍铁基析氧催化剂本体,然后在其上制作SiO_(2)膜层材料,得到SiO_(2)-镍铁基复合析氧催化剂。采用CH660E电化学工作站对催化剂进行电化学测试,发现S2催化剂优于其他催化剂的析氧反应活性,过电位η10达到230 mV,比对照组S0降低17.8%,稳定电流密度提高了110.45%,达到15.3 mA/cm^(2),转移电阻值降低16%。通过SEM形貌观察,EDS元素分析,HR-TEM观察其表面形态,研究了这种SiO_(2)-镍铁基复合析氧催化剂表面材料形态及分布对其电催化性能的影响。

天然气-二氧化碳-水蒸气-氧转化制合成气的研究——稀土助剂的作用

研究了稀土氧化物 (CeO2 和La2 O3)改性的镍基催化剂中助剂的作用 ,并考察了催化剂对天然气 二氧化碳 水蒸气 氧转化制合成气反应的活性 .结果表明 ,La2 O3 改性的镍基催化剂具有较高的CH4 转化率和H2 选择性 ;经CeO2 改性的镍基催化剂具有较高的CO选择性 .量子化学计算和XRD研究结果表明 ,La2 O3 助剂的加入 ,可使还原后催化剂表面Ni(111)晶面衍射峰的强度减小 ,较好地符合吸附活化CH4 分子的“尺寸效应”和能量要求 .添加CeO2 助剂的催化剂 ,其Ni(111)晶面衍射峰强度较大 ,而Ni(110 )晶面含量最小 ,不利于CH4 的离解 .同时 ,助剂RE2 O3(尤其是CeO2 )和MgO提高了Ni的d电子密度 ,因而一定程度上加强了Nid电子向CO2 空反键π轨道的迁移 ,促进CO2 分子的活化 。

非负载镍催化剂的2-乙基蒽醌加氢活性及其氢吸脱附性质

分别制备了金属镍粉、兰尼镍、Ni B非晶态合金及镧掺杂的Ni B非晶态合金 (Ni B La)催化剂 ,研究了催化剂的氢吸附和脱附性质以及对 2 乙基蒽醌加氢反应的催化性能 .结果表明 ,金属镍粉、兰尼镍和Ni B催化剂表面均具有两种氢吸附位 :弱吸附位和强吸附位 .Ni B La催化剂表面只有氢的强吸附位 ,其强吸附氢量与兰尼镍相当 .推测只有氢的强吸附位是 2 乙基蒽醌加氢反应的活性中心 ,并且Ni B La催化剂上的强吸附氢较兰尼镍上的更活泼 ,因而Ni B La非晶态合金催化剂对加氢反应的催化活性高于兰尼镍 .

等离子体技术制备Ni/α-Al_2O_3催化剂

采用射频辉光放电等离子体技术制备了用于天然气部分氧化制合成气反应的α Al2 O3担载金属Ni催化剂。考察了该催化剂的反应活性、稳定性 ,并与常规方法制备的催化剂进行了比较。结果表明 ,采用等离子体技术制备的催化剂 ,具有操作简便、工艺流程短、催化剂变化过程直观易控、催化剂活性高、稳定性好等优点 ,在 850℃反应时可获得 98 2 %天然气转化率 ,97 3%H2 选择性和 96 5%CO选择性 ,并且反应 1 5h后催化剂活性几乎未下降。XRD和TPR实验结果表明 ,采用等离子体技术制备的催化剂的晶相组成和还原性能与常规催化剂有很大差别。

热处理对高硫化氢合成气一步法制甲硫醇K2MoO4-NiO/SiO2催化剂结构及性能的影响

在不同焙烧温度和焙烧气氛下对共浸渍法制备的K2MoO4-NiO/SiO2催化剂进行热处理,并采用X射线衍射、热重-差示扫描量热、氢气程序升温还原、拉曼光谱和电子自旋共振波谱等手段对催化剂进行了表征,同时考察了催化剂催化高硫化氢合成气一步法制甲硫醇的性能.结果表明,由于催化剂中所含柠檬酸氧化放热,空气中焙烧的催化剂发生严重烧结.随着焙烧温度的升高,八面体配位的Mo(Oh)逐渐向四面体配位的Mo(Td)转变,导致催化剂的还原能力降低,配位不饱和Mo(CO吸附位)减少,因而CO转化率降低.甲硫醇的生成与Mo–S–K相密切相关,而MoS2晶相表面主要生成烃类.与氮气中焙烧的催化剂相比,空气中焙烧的催化剂表面的MoS2相较多,而Mo–S–K相较少,因此具有更高的烃类选择性和更低的甲硫醇选择性.

乙烯齐聚合成线性α-烯烃镍系催化剂

利用SHOP型工艺由乙烯齐聚制备线性α-烯烃不仅具有工业应用价值,而且具有很高的学术意义。SHOP型工艺的工业化引起了人们对基于P∩O配位型及其他配位型镍催化剂的广泛的研究兴趣。镍系催化剂具有活性高、选择性好、产品分布可调、反应条件温和等优良性能。本文介绍了镍系催化剂的类型和性能等,并对影响催化性能的因素进行了分析。