共查询到19条相似文献,搜索用时 62 毫秒
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板状镍催化剂上氨分解和氨部分氧化制氮氢气的研究 总被引:1,自引:0,他引:1
研制了一种 Ni/Al2O3多孔板状催化剂.该催化剂在反应温度高于750℃,氨分解率高于99.5%时,允许反应空速达10000—40000h-1.用该催化板组装的反应器可采用内加热形式,和一般的外加热反应器相比可节约能耗约30%.在催化板上氨分解的经验动力学方程是γ=kp2NH3,表观活化能为153.0kJ/mol.将该催化剂用于氨部分氧化时,在空气和氨比为1.0—1.7,680—750℃,氨空速10000—40000h-1条件下,在氨点火后无外加能源情况下,能制得含氢30~43%,残氧小于0.1%的氮氢混合气,氨的转化率>99.5%,连续250小时反应表明,催化剂活性稳定.宏观动力学研究得出,反应对氨呈零级,表观活化能为37.2kJ/mol. 相似文献
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氢能源作为重要的绿色能源,其制备与应用引起了研究者的极大关注。氨分解在线制氢能够有效解决氢能源储存运输的难题,可以制备得到无碳氧化物杂质的高纯度H2,但氨分解反应的活化能较高、反应条件苛刻,因此开发高效氨分解催化剂对氢能源产业发展具有重要意义。稀土氧化物具有较强的表面碱性和良好的热稳定性,其特殊的4f轨道电子结构使其具有储存和释放电子的潜力,易于与活性金属形成结构稳定的界面位点以及增加活性金属的电子密度。因此将稀土材料作为组成部分应用到构建高效稳定的氨分解反应催化剂中具有广阔的研究前景。本文总结了稀土基催化剂催化氨分解反应的进展,对其可以高效促进氨分解反应的内在原因进行了分析,并且对稀土基氨分解催化剂的构效关系揭示和可能的性能优化途径进行了展望。 相似文献
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贵金属助剂促进的费-托合成用钴基催化剂具有高活性和长链烃(C5+)选择性优越等特点,被广泛应用于由合成气制清洁燃料的合成反应中。 本文重点讨论了贵金属助剂对活性钴物种的结构(还原度、分散度、双金属颗粒或合金的构成), 钴基催化剂稳定性以及其对费-托合成的反应速率和产物选择性的影响规律。 相似文献
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高温煤气中氨的脱除:Ⅰ.氨催化分解催化剂的筛选 总被引:3,自引:0,他引:3
制备和筛选了12 种氨催化分解催化剂,所选催化剂包括Cu - Mn 基脱硫剂,Zn- Ti 基脱硫剂,Fe 基催化剂及Ni 基催化剂四大类,其中Ni-2 催化剂及Ni- 3 催化剂具有较高的转化率。然后对Ni-3 催化剂进行了寿命试验,100h 内其活性基本维持不变;耐硫性实验表明Ni-3 催化剂具有一定的耐硫性能,因而它是所选的最优催化剂 相似文献
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研究了Ni- 3催化剂分解氨的动力学。考察了各种反应条件如温度、空速以及气体中的氨和氢的浓度对反应的影响,确立了氨催化分解动力学方程式。当操作空速为3000h- 1 时,在580 ~630℃的温度区间内,反应主要受化学反应控制;在630~700℃的温度区间内,反应受扩散影响较为严重;在700℃以上的温度区间内,反应在一定程度上受平衡的影响。随着空速的增大反应速率增大,但转化率却有所减小;气体中氨浓度的增大对反应转化率没有什么影响,氢浓度的增大使反应转化率明显减小。在580~630℃的温度范围内,空速3000h- 1 的操作条件下动力学方程式如下:R= 3.423×1013e- 276 .45 ×103RT CNH3·C- 1-5H2 相似文献
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《Journal of Energy Chemistry》2014,23(1):1-8
Electrolysis of ammonia in alkaline electrolyte solution was applied for the production of hydrogen. Both Pt-loaded Ni foam and Pt-Ir loaded Ni foam electrodes were prepared by electrodeposition and served as anode and cathode in ammonia electrolytic cell, respectively. The electrochemical behaviors of ammonia in KOH solution were individually investigated via cyclic voltammetry on three electrodes, i.e. bare Ni foam electrode, Pt-loaded Ni foam electrode and Pt-Ir loaded Ni foam electrode. The morphology and composition of the prepared Ni foam electrode were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Effects of the concentration of electrolyte solution and temperature of electrolytic cell on the electrolysis reaction were examined in order to enhance the efficiency of ammonia electrolysis. The competition of ammonia electrolysis and water electrolysis in the same alkaline solution was firstly proposed to explain the changes of cell voltage with the electrolysis proceeding. At varying current densities, different cell voltages could be obtained from galvanostatic curves. The low cell voltage of 0.58 V, which is less than the practical electrolysis voltage of water (1.6 V), can be obtained at a current density of 2.5 mA/cm2. Based on some experimental parameters, such as the applied current, the resulting cell voltage and output of hydrogen gas, the power consumption per gram of H2 produced can be estimated. 相似文献
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采用液相还原法制备非负载型镍催化剂,将非负载型镍催化剂分散在液相供氢溶剂十氢萘中,催化合成气甲烷化反应。在高压反应釜内,考察了反应温度、物质的量比等操作条件下,镍催化剂催化合成气甲烷化反应的反应活性。并对催化剂进行XRD、SEM、H2-TPR表征分析。研究结果表明,在330℃、催化剂用量为2%时,产品气中甲烷含量可达89.39%,CO和H2的转化率分别为94.56%和92.60%;催化剂用量为4%时,产品气中甲烷含量可高达94.26%,CO的转化率可达到99%以上。合成气甲烷化反应的最佳操作温度为330℃,H2/CO物质的量比最佳为2.20~2.67。 相似文献
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采用蒸氨法制备Cu/SiO2催化剂,分别考察气相二氧化硅(SiO2-aer)、硅胶(SiO2-gel)和碱性硅溶胶(SiO2-sol)对Cu/SiO2催化剂催化甲醇裂解制氢性能的影响,并采用N2吸附-脱附、N2O化学吸附、电感耦合等离子体原子发射光谱法(ICP-AES)、X射线衍射(XRD)、H2程序升温还原(H2-TPR)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等方法对催化剂进行表征。结果表明,硅源对Cu/SiO2催化剂的活性具有较大影响。以碱性硅溶胶作为硅源制得的Cu/SiO2-sol催化剂比表面积较大,活性中心粒径较小且分散均匀,这些使得其制氢性能优于其他两种硅源为载体所制备的催化剂。在反应温度280 ℃,反应压力1 MPa,甲醇质量空速0.6 h-1的条件下,相较于Cu/SiO2-aer和Cu/SiO2-gel催化剂,Cu/SiO2-sol催化剂的甲醇转化率分别提高10%和7%,气相副产物CH4和CO2浓度也有所降低,该催化剂上的甲醇转化率和气体收率分别达到98.4%和96.7%。 相似文献
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分别用H2O2、强碱(NaOH、KOH)和HNO3处理CNTs。以处理后的CNTs为载体、通过浸渍RuCl3水溶液结合高温H2还原制备Ru/CNTs催化剂,并将其应用在氨分解催化反应中。利用XRD、TPR、TPD-MS表征手段研究了Ru在CNTs表面的分散、还原性能及CNTs表面化学基团,探究催化剂结构-性能间构效关系。结果表明,强碱及双氧水处理CNTs,为其表面引入了数量适宜的羧基、酸酐、酚等官能团,而传统硝酸处理则引入了大量的羧基、酸酐、酯、内酯、酚、醌和羰基等官能团,对CNTs本征结构性质影响很大。经强碱及双氧水处理CNTs上负载Ru后所得催化剂的效果明显优于传统硝酸处理CNTs上负载Ru催化剂。本研究为CNTs的新型处理方法、表面化学官能团分析、提高Ru/CNTs催化分解氨活性提供了新的思路。 相似文献
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Preparation of novel Ni-Ir/r-Al2O3 catalyst via high-frequency cold plasma direct reduction process 下载免费PDF全文
The novel Ni-Ir/γ-Al2O3 catalyst was prepared by high-frequency cold plasma direct reduction method (NIA-P) under ambient conditions
without thermal treatment, and the conventional sample was prepared by impregnation, thermal calcination, and then by H2 reduction method
(NIA-CR). The effects of reduction methods on catalysts for ammonia decomposition were studied, and the catalysts were characterized by
XRD, N2 adsorption, XPS, and H2-TPD. It was found that the plasma-reduced NIA-P sample showed a better catalytic performance, over
which ammonia conversion was 68.9%, at T = 450 ℃, P = 1 atm, and GHSV = 30, 000 h−1. It was 31.7% higher than that of the conventional
NIA-CR sample. XRD results showed that the crystallite size decreased for the sample with plasma reduction, and the dispersion of active
components was improved. There were more active components on the surface of the NIA-P sample from the XPS results. This effect resulted
in the higher activity for decomposition of ammonia. Meanwhile, the plasma process significantly decreased the time of preparing catalyst. 相似文献
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《Journal of Energy Chemistry》2014,23(1):50-56
Core-shell structured nanospheres with mesoporous silica shell and Ni core (denoted as Ni@meso-SiO2) are prepared through a three-step process. Monodispersed Ni precursors are first prepared, and then coated with mesoporous SiO2. Final Ni@meso-SiO2 spheres are obtained after calcination. The products are characterized by X-ray powder diffraction, transmission electron microscopy and N2 adsorption-desorption methods. These spheres have a high surface area and are well dispersed in water, showing a high catalytic activity with a TOF value of 18.5, and outstanding stability in hydrolytic dehydrogenation of ammonia borane at room temperature. 相似文献
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Hongchao Liu Hua Wang Jianghan Shen Ying Sun Zhongmin Liu 《Reaction Kinetics and Catalysis Letters》2008,93(1):11-17
The high-throughput technique has been successfully employed to investigate systematically NH3 decomposition catalysts for COx-free hydrogen production. Supported γ-Mo2N catalysts not only could be prepared and evaluated by the high-throughput experiment, but are also active for NH3 decomposition luke supported Ni and Co catalysts. Additionally, the preparation process and support play important roles
on the catalytic performance of supported γ-Mo2N catalysts. 相似文献