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LaNiAl11O19催化剂上甲烷与二氧化碳重整反应的研究 总被引:2,自引:2,他引:2
目前用于甲烷与二氧化碳重整反应研究的催化剂主要是负载镍及贵金属的催化剂,在较高的反应温度下,这类催化剂的载体和金属容易烧结,而且相互之间容易发生因相反应,从而导致催化剂失活[1.2].因此,我们从高温稳定的载体材料人手,选择具有六铝酸盐结构的复合氧化物作为催化剂的基质材料,将镍离子镶嵌在复合氧化物特定的晶格位置上,一方面可提高镍离子的分散度和抗烧结能力,另一方面可以通过离子调变,改变催化剂表面酸碱性,提高催化剂抗积炭性能.实验结果表明,LaNiAl11O19不仅具有较高的甲烷与二氧化碳重整反应活性,而且镍离子… 相似文献
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用热重(TGA)方法,研究了LaNiAl11O19和SrNi11O19催化剂上甲烷与二氧化碳重整反应的积炭动力学。实验结果表明,甲烷裂解是CH4+CO2反应中主要的积炭反应,甲烷的二氧化碳重整反应的积炭速率随反应温度升高而增大,但春衰减速度也较快;CH4+CO2反应的积炭速率相对甲烷分压的反应级数是1,相对二氧化碳分压的反应级数是一-05;在SrNiAl11O19中掺入La^3+离子,提高了催化剂 相似文献
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利用 X 射线粉末衍射、氢程序升温还原、X 射线光电子能谱和透射电镜技术研究了在低 Ni 含量和低比表面积六铝酸盐催化剂 LaNiAl11O19-δ 上 CH4-CO2 重整反应的积炭行为, 考察了该催化剂表面积炭的形貌、来源、积炭物种及其反应性能. 结果表明, LaNiAl11O19-δ 催化剂表面积炭主要由甲烷裂解产生, 并以 Ni 的碳化物形式存在于活性中心 Ni 的周围. 根据积炭物种活化程度的难易可分为 Cα, Cβ和 Cγ 三种类型, 其中 Cα 为容易被 CO2 消除的化合碳, 而 Cβ 和 Cγ则是不易被 CO2 消除的石墨碳. 透射电镜结果表明, Cα 以碳纳米管形式分布于催化剂颗粒周围, 但金属 Ni 活性中心仍能暴露于气相中, 因而不影响催化剂的活性. 相似文献
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甲烷重整制合成气镍催化剂积炭研究 总被引:1,自引:0,他引:1
本文综述了甲烷转化制合成气镍催化剂积炭的研究进展,论述了积炭热力学和动力学、积炭类型、积炭机理和影响积炭的因素,详细分析了催化剂的镍粒子尺寸、镍-载体相互作用、载体碱性强度、载体氧化-还原性质和添加助剂对镍催化剂的积炭速率和积炭量的影响,并总结了重整反应工艺参数和反应器形式对镍催化剂积炭的影响。最后指出,采用现代表征手段阐明镍催化剂的积炭机理、种类和数量,明确积炭的规律,可为设计开发抗积炭性能强的镍催化剂提供理论依据;可通过增强金属与载体的相互作用、减小镍粒子的尺寸(镍粒子尺寸小于20 nm)和选择适宜的载体来制备抗积炭性能强的催化剂;可通过采用流化床反应器且优化工艺参数来减少重整过程积炭量;可通过寻求行之有效的积炭催化剂再生方法来解决镍催化剂积炭问题。 相似文献
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采用浸渍法制备了一系列MTiO3(M=Mg、Ca、Sr、Ba)钙钛矿型氧化物负载的Ni催化剂(Ni的负载量为5%,质量分数),通过XRD、氮吸附、H2-TPR、CO2-TPD、XPS和TG等技术对催化剂进行了表征,对其甲烷二氧化碳重整反应的催化性能进行了研究。结果表明,M为不同碱土金属时,催化剂上金属载体相互作用、活性组分的表面原子浓度以及催化剂晶格氧的流动性都发生了变化。Ni/CaTiO3催化剂上金属载体相互作用较强,还原出的活性组分Ni的含量较多,晶格氧流动性较高,因而具有较好的催化性能。SrTiO3载体颗粒粒径较大,Ni/SrTiO3催化剂上Ni的分散度不高,金属载体的相互作用较弱,表面Ni原子相对含量较低,晶格氧的流动性较差,其甲烷二氧化碳重整反应活性也最低。 相似文献
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Kinetics of Carbon Deposition on Hexaaluminate LaNiAl11O19 Catalyst During CO2 Reforming of Methane
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Zhanlin Xu Shuyong Jia Lina Zhao Yurong Ren Yan Liu Yingli Bi Kaiji ZhenCollege of Chemistry Jilin Normal University Siping China College of Chemistry Jilin University Changchun China 《天然气化学杂志》2003,12(3):189-194
In this paper, the properties of carbon deposited on hexaaluminate LaNiAl11O19 catalyst were characterized by X-ray photoelectron spectroscopy (XPS), and in the meantime, the amount of carbon deposited on the catalyst, after both CH4 decomposition and CO2 reforming of CH4, was determined by means of thermogravimetric analysis (TGA), respectively. The rates of carbon deposited on the catalyst were also investigated and the apparent kinetic equation of CO2 reforming of CH4: vc = kp0.72(CH4).p-0.55(CO2), was established by analyzing the relation between the rates of deposited carbon and the pressure ratio of CH4 and CO2. 相似文献
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The performance of a new lab-made bifunctional material Ni/Al2O3/KNaTiO3 for producing high purity H2 via sorption-enhanced steam methane reforming (SESMR) was investigated. A series of bifunctional materials with 10 wt% Ni loading but different wt% ratios of KNaTiO3 and Al2O3 was prepared by wetness impregnation method. All the materials were calcined at 700 °C for 3 hours and screened for their catalytic activity in a continuous flow fixed-bed reactor. The material containing 50 wt% each of KNaTiO3 and Al2O3 (designated as HM) was found to be the best choice. The optimum process parameters for the production of high purity H2 were determined: temperature = 700 °C, steam to carbon (S/C) molar ratio = 6 and gas-hourly space velocity (GHSV) = 2000 cm3 g-1 h-1. The values of CH4 conversion, H2 yield and H2 purity were 87, 87 and 90%, respectively, at the optimum reaction conditions. The adsorption capacity of HM was found to be 14.7 wt%. With a breakthrough time of 10 min, the material was stable for 8 adsorption-desorption cycles. The regeneration of HM was achieved with N2 gas at the same reaction temperature. Overall, the activity of this material for SESMR was very promising. 相似文献
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CO偶联临氢反应Pd-Fe/Al2O3催化剂的XPS研究 总被引:2,自引:0,他引:2
利用XPS及氩离子溅射等技术对CO偶联和临氢反应中所用催化剂\r\n表面活性组分和助剂的含量及其化学状态进行了分析,并通过测定氢在\r\n催化剂表面的化学吸附,以及氢浓度对催化剂活性的影响,探讨了CO偶\r\n联反应中催化剂临氢失活的主要原因.XPS表征结果表明,CO偶联反应\r\n中催化剂活性组分以Pd0和Pd2+形式共存;而临氢反应后仅以Pd0形式\r\n存在,助剂FeO从催化剂的内部向表面迁移且有少量Fe2+转变为Fe3+\r\n.催化剂临氢失活的主要原因是H2在活性组分Pd及助剂Fe(主要是FeO\r\n)表面均可形成解离吸附,形成的金属氢化物可在低活化能条件下发生\r\n迁移.这种迁移有利于副产物乙醇的生成,从而削弱了CO偶联主反应,\r\n催化剂表面活性组分Pd的相对含量减少,并几乎处于钝化状态,导致临\r\n氢反应中CO转化率、草酸二乙酯选择性及空时收率均下降.停止通入H\r\n2后,催化剂的活性可恢复至正常状态. 相似文献
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We present horizontally‐oriented multiwalled carbon nanotubes (CNTs) grown by means of thermal chemical vapor deposition. The CNT is across the trenches of the catalytic metals on predefined Ti electrodes. The properties of the lateral multiwalled CNT, following post‐ammonia plasma treatment, are reported. Information about the ammonia plasma treated on the interface structure of CNT is obtained using X‐ray photoelectron spectroscopy. The experimental results show that upon exposure to ammonia, the electrical property of the CNT is found to increase. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Liu Yan Xu Zhanlin Cheng Tiexin Zhou Guangdong Wang Junxia Li Wenxing Bi Yingli Zhen Kaiji 《Kinetics and Catalysis》2002,43(4):522-527
The amount of carbon deposited on hexaaluminate LaNiAl11O19 catalyst in CH4 decomposition and CO2 reforming of methane was determined by means of thermogravimetric analysis (TGA). The properties of carbon formed on the catalysts were characterized by X-ray photoelectron spectroscopy (XPS), temperature-programmed CO2 reaction (TPR-CO2), and temperature-programmed oxidation (TPO) techniques. The experimental results showed that hexaaluminate LaNiAl11O19 catalyst possessed high resistance to carbon deposition in CO2 reforming of methane to synthesis gas at high temperatures, and CO2 played an important role in eliminating carbon during the reaction. At least two forms of the deposited carbon, graphite and carbide, were produced during methane reforming with CO2. 相似文献
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Anton Purnomo Susan Gallardo Leonila Abella Chris Salim Hirofumi Hinode 《Reaction Kinetics and Catalysis Letters》2008,95(2):213-220
The characterization and catalytic activity of a Ni/CeO2/ZrO2 catalyst for methane steam reforming at 600°C were investigated. The addition of ceria increased the surface area and basicity
of the catalysts. The redox reaction capability of the ceria increased the hydrogen yield and carbon monoxide selectivity,
and inhibited carbon formation. 相似文献
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《Comptes Rendus Chimie》2015,18(11):1242-1249
The activity of ceria–zirconia-supported nickel catalysts (Ni/CZ) with various loadings of nickel (2, 4 and 10 wt. %) was studied in the case of low-temperature dry reforming of methane (DRM). XRD, SBET, SEM, TPD-CO2 and thermogravimetry were used to determine the physicochemical properties of the catalysts and of the carbon deposits formed on the surface. It was found that the agglomerates of the Ni-active phase are formed on the surface of the support for high loadings of nickel. The best conversions of CO2 and CH4 and an optimum ratio H2/CO = 1 were obtained for the catalysts with the highest Ni content. It was also found that loading has an influence on the amount of carbon deposits formed in the DRM process. 相似文献
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羟基磷灰石负载Ni催化剂中Ni含量对催化甲烷二氧化碳重整制合成气性能的影响 《燃料化学学报》2014,42(4):461-466
以低温沉淀方法制备的羟基磷灰石(HAp)为载体,采用浸渍法制备了一系列不同Ni含量的Ni/HAp催化剂,并采用BET、H2-TPR、XRD、SEM、FT-IR、TEM和TG-DTA技术对催化剂进行了表征。结果表明,NiO含量为13%的催化剂表现出最好的催化甲烷二氧化碳重整制合成气活性,在850℃、空速3.6×104mL/(h·gcat)的反应条件下,甲烷和二氧化碳的转化率在10 h内分别稳定在72%和83%。这主要归因于催化剂中金属和载体之间的强相互作用。虽然反应后的催化剂表面有少量的积炭,但这些积炭多以丝状炭存在,并不会影响催化剂的活性和稳定性。 相似文献