共查询到20条相似文献,搜索用时 15 毫秒
1.
M. Hrabovsky M. Hlina V. Kopecky A. Maslani P. Krenek A. Serov O. Hurba 《Plasma Chemistry and Plasma Processing》2018,38(4):743-758
Reactions of methane with water and CO2 in thermal plasma generated in a special plasma torch with a water-stabilized arc were investigated. Steam plasma with very high enthalpy and low mass flow rate was produced in a dc arc discharge which was in direct contact with water vortex surrounding the arc column. Composition of produced gas, energy balance of the process and its efficiency were determined from measured data. The output H2/CO ratio could be adjusted by a choice of feed rates of input reactants in the range 1.1–3.4. Depending on experimental conditions the conversion of methane was up to 99.5%, the selectivity of H2 was up to 99.9%, and minimum energy needed for production of 1 mol of hydrogen was 158 kJ/mol. Effect of conditions on process characteristics was studied. Comparison of measured data with results of theoretical computations confirmed that the reforming process produces gas with composition which is close to the one obtained from the thermodynamic equilibrium calculations. Relations between process enthalpy, composition of produced syngas and process characteristics were determined both theoretically and experimentally. 相似文献
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Naser Seyed-Matin Amir Hossein Jalili Masih Hosseini Jenab Seyed Majid Zekordi Ali Afzali Chapar Rasouli Akbar Zamaniyan 《Plasma Chemistry and Plasma Processing》2010,30(3):333-347
The carbon dioxide reforming of methane to synthesis gas under DC-pulsed plasma was investigated. The effects of specific
input energy and feed ratio on the product distribution and also feed conversion was studied. At the input energy of about
11 eV/molecule per methane and/or carbon dioxide the feed conversion of 38% for CH4 and 28% for CO2 and product selectivity of 74% has been attained for H2 and CO at feed flow rate of 90 ml/min. The energy consumption in this work displays potential to further study and optimization
of the process. The importance of the electron impact reactions in the process was discussed. The results show that by prudent
tuning of system variables, the process be able to run in the way of synthesis gas, instead of hydrocarbon production. 相似文献
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Dr. Petr Šot Dr. Mark A. Newton Dr. Dirk Baabe Prof. Dr. Marc D. Walter Dr. Alexander P. van Bavel Dr. Andrew D. Horton Prof. Dr. Christophe Copéret Prof. Dr. Jeroen A. van Bokhoven 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(36):8012-8016
Non-oxidative CH4 coupling is promoted by silica with incorporated iron sites, but the role of these sites and their speciation under reaction conditions are poorly understood. Here, silica-supported iron(II) single sites, prepared via surface organometallic chemistry and stable at 1020 °C in vacuum, are shown to rapidly initiate CH4 coupling at 1000 °C, leading to 15–22 % hydrocarbons selectivity at 3–4 % conversion. During this process, iron reduces and forms carburized iron(0) nanoparticles. This reactivity contrasts with what is observed for (iron-free) partially dehydroxylated silica, that readily converts methane, albeit with low hydrocarbon selectivity and after an induction period. This study supports that iron sites facilitate faster initiation of radical reactions and tame the surface reactivity. 相似文献
4.
研究了以冷轧工艺制备的Ni3Al单晶箔(Ni-24at% Al), 以及表面预处理(873 K下蒸汽氧化后还原处理)后的Ni3Al箔, 在甲烷重整制氢反应中的催化性能. 首先, 采用逐步升温法研究了873~1173 K下Ni3Al箔的催化活性与温度的关系; 然后, 采用等温法研究了973 K下Ni3Al箔的催化稳定性. 根据催化反应和扫描电镜显微观察的结果得出: 未经预处理和经过预处理的Ni3Al箔, 在反应中均显示出一定的催化活性和稳定性; 表面预处理对Ni3Al箔的催化活性有显著的增强作用, 原因是经过该预处理后的Ni3Al箔形成了富Ni表面; Ni3Al箔在甲烷重整反应的气氛中, Ni原子从Ni3Al基体向表面的移动, 是维持催化活性的主要原因. 相似文献
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Sergio L.González Cortés 《高等学校化学研究》2004,20(4):457-461
A series of Co/γ-Al2O3 catalysts were prepared with the impregnation .method and characterized by means of the BET specific surface area, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Laser Raman spectroscopy. The Co/γ-Al2O3 catalysts were activated by using H2, 20%CH4/H2 or CH4, re-spectively. There was no obvious difference between the activities of the Co/γ-Al2O3 catalyst activated by us-ing the different activation methods for methane dry reforming. The catalytic properties of the Co/γ-Al2O3 catalysts with different Co loadings were also investigated. The optimized Co loading for the Co/γ-Al2O3 cata-lyst pretreated with 20% CH4/H2 is around 12% (mass fraction). 相似文献
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随着工业化的推进,化石能源的消耗产生大量温室气体,其中CH4和CO2占据温室气体排放的98%以上。将CH4和CO2转化为高附加值化学品具有重要的意义,一直受到工业界和学术界广泛关注。传统的热催化甲烷干重整(DRM)可实现将CH4和CO2转化为合成气,但该反应过程受热力学限制,需要很高的能量输入,并且由于反应温度较高,催化剂易发生积碳而失活。绿色环保的光催化技术可以使甲烷干重整反应在温和条件下进行,但是存在太阳光利用率和反应转化率较低等问题。最近光热协同催化受到学术界广泛关注。许多研究结果表明,在相对温和的条件下,光热催化DRM可以获得良好的催化效果,可有效实现太阳能转化为化学能。本文简要介绍近期光热催化甲烷干重整反应的研究进展,总结不同金属催化剂在光热催化甲烷干重整中的应用,同时提出了光热催化甲烷干重整存在的一些挑战及展望。 相似文献
7.
The promotion effects of nickel catalyst of dry reforming with methane were extensively investigated by means of XRD, SEM, EDX, N2‐adsorption and H2‐adsorption. XRD characterization indicated that good dispersion of nickel oxide and MgO promoter is achieved over γ‐Al2O3 support. Addition of MgO promoter effectively retards the formation of NiAl2O4 phase. SEM and EDX analysis exhibited that the addition of rare‐earth metal oxide CeO2 effectively promotes the Ni metal dispersion on the surface of the catalysts despite of undesirable self‐dispersion of CeO2 promoter. Furthermore, the nickel component is gradually dispersed on the surface of the support following the exposure to reaction gas mixture for a period of time. The addition of MgO inhibited the self‐dispersion and promotion effect of CeO2 on Ni dispersion on the catalysts. H2 chemisorption revealed that the addition of the alkaline oxide MgO promoter significantly prohibits the metal dispersion on the catalyst. Inappropriate promoter addition can result in sharp decrease of the metal dispersion, N2‐adsorption indicated that oxide promoter was mostly concentrated on the outer layer of the alumina support while the nickel metal was generally dispersed in the support pores. Addition of promoters contributed to more reduction in mesopore volume. 相似文献
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采用反应蒙特卡罗方法研究了狭缝孔内甲烷蒸汽重整反应的化学平衡. 模拟中将CH4, CO和H2均描述成球形LJ分子, H2O和CO2分子的势能分别采用TIP4P和EMP2模型计算. 狭缝孔壁与LJ点位之间的相互作用采用Steele的10-4-3模型计算. 由于没有狭缝孔内该反应的实验数据, 因此比较了用经典热力学预测与RCMC方法得到的主体相平衡组成. 两种方法得到的结果比较吻合, 表明采用RCMC方法预测孔内的化学平衡是可靠的. 讨论了其它工艺条件对孔内化学平衡的影响. 相似文献
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采用焙烧记忆法分别制备Ni/Mg Al O和NiRu/Mg Al O类水滑石催化剂用于甲烷干重整反应.利用XRD、TPR、TG、XPS、CO2-TPD、TEM等表征催化剂的结构及失活特征,发现在Ni/Mg Al O中添加Ru,有利于增加催化剂表面Ni含量,并促进Ni2+的还原.不同Mg/Al比双金属催化剂中,7Ni-0.15Ru/Mg2.5Al催化剂具有较高的催化活性,这归结为该催化剂适宜的碱性、较高表面Ni含量以及小尺寸的Ni0物种.添加Ru明显抑制Ni/Mg Al O催化剂表面的丝状碳的形成.而7Ni-0.15Ru/Mg2.5Al较强的抗积碳性能与其较小Ni0晶粒尺寸及适宜催化剂碱性有关. 相似文献
12.
甲烷无氧芳构化(MDA)和甲烷水蒸气重整(MSR)的耦合反应可以大幅度提高甲烷无氧芳构化反应的稳定性.单独的甲烷无氧芳构化反应失活较快,甲烷转化率从0.5 h的14.5%很快下降至15 h的3.5%.而采用联合MSR/MDA反应体系,甲烷的转化率从12.5 h的11.5%非常缓慢地下降至60 h后的6.5%.MSR反应原位生成的CO和H2能降低反应中生成的CHr物种数量,减少催化剂上积炭的牛成,进而延长反应时间.MSR反应过程中高比例H2的生成更能有效地减少与B酸相关的积炭的生成,从而更好地抑制反应的失活. 相似文献
13.
钙钛矿材料在催化领域具有广泛的应用,其微观结构的调控对催化性能有显著的影响.我们采用柠檬酸配合法、溶胶凝胶法、燃烧法和浸渍法一系列不同的制备过程对镍基钙钛矿材料的结构进行调控,并将其应用于甲烷干重整反应,研究了制备方法对活性组分Ni的化学形态、Ni与基底的相互作用以及活性氧物种的调控,进而影响其催化活性和抗积碳能力.结果表明,燃烧法可以显著提高催化剂的结晶度,从而提高Ni与基底的相互作用以及表面氧物种的含量,使其具有较强的抗积碳能力.燃烧法合成的Ni基钙钛矿催化剂在CH4∶CO2=1.25∶1,800℃的条件下反应300 h后,积碳量仅为1.0%,而在同样条件下浸渍法合成的催化剂积碳量则高达14.6%. 相似文献
14.
Low temperature conversion of CH4 and CO2 was investigated in a coaxial dielectric barrier discharge reactor at ambient pressure. Main parameters, including the input
power, the residence time, the discharge gap, the molar ratio of the feed gases and the multi-stage ionization design were
evaluated to understand the ways to improve the conversion of greenhouse gases and reduce the output of by-products. At certain
input power, the conversion of CH4 and CO2 can reach 0.797 and 0.527, respectively, when the molar ratio of CH4/CO2 is one. When this ratio was low to 1:5, the conversion of CH4 was promoted to 0.843 and the selectivity to CO and H2 was almost 100%. The multi-stage ionization favored the conversion of CO2, which would also be an efficient design to promote the selectivity to the main products such as CO and H2 and suppress the selectivity to the by-products. 相似文献
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太阳能作为一种最丰富的可再生能源, 具有其它能源所不可比拟的优点 [1~3]. 太阳能取之不尽、用之不竭, 太阳每年向地球辐照的能量大约是5.4×1024焦耳. 与核能相比, 太阳能更为安全;与水能、风能相比, 太阳能利用的成本较低, 而且不受地理条件的限制. 全世界范围每年需要的能源相当于8×109吨煤, 也就是1.09×1020焦耳的能量. 如果辐照地球上一小部分的太阳能能被利用的话, 许多能源问题都可能迎刃而解. 相似文献
16.
Mohammad Mahdi Moshrefi Fariborz Rashidi Hamid Reza Bozorgzadeh Mohammad Ehtemam Haghighi 《Plasma Chemistry and Plasma Processing》2013,33(2):453-466
A novel type of plasma reactor having a rotating electrode is proposed for CO2 reforming of methane without catalyst at room temperature and atmospheric pressure. Results indicated that employing rotating ground electrode leads to a stable discharge for any period of time. Effects of feed composition, feed flow rate, applied power and electrodes separation on the carbon dioxide and methane conversions as well as the products selectivity were investigated. Increasing CO2/CH4 molar ratio in the feed favors the reagents conversion and consequently promotes the formation of hydrogen and carbon monoxide. If the target product is hydrogen, it is proposed to operate the reactor at CO2/CH4 = 1 molar ratio and if the target product is carbon monoxide then CO2/CH4 = 3 molar ratio is the preferred option for feed composition. This reactor system has advantages of stable operation and high conversion ability. Also, the obtained syngas with flexible molar ratio of H2 to CO is suitable for vast industrial applications. 相似文献
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Pourali Nima Hessel Volker Rebrov Evgeny V. 《Plasma Chemistry and Plasma Processing》2022,42(3):619-640
Plasma Chemistry and Plasma Processing - The conversion of methane to ethylene has been investigated in a micro-DBD reactor with electrodes containing charge injector parts and excited with a... 相似文献
19.
Anatta Wahyu Budiman Sang-Hoon Song Tae-Sun Chang Chae-Ho Shin Myoung-Jae Choi 《Catalysis Surveys from Asia》2012,16(4):183-197
Dry reforming of methane produces syngas with desirable H2/CO ratio. Besides noble metal catalysts, the cobalt catalyst performs good activity in this reaction. However, carbon deposition and catalyst deactivation are becoming the main problems inhibiting the scale up of this process into industrial application. Recently, many scientists were trying to increase the activity as well as the stability toward coking by using variants of support, promoter, and combination of metal series catalyst. This paper presents a recent technology of methane dry reforming over cobalt metal-base catalyst, covering the catalyst activity and their resistance of catalyst deactivation. 相似文献
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A series of ternary perovskite type oxides LaNi1-xCuxO3(x = 0.2,0.4,0.6,0.8,and 1.0) were synthesized via the sol-gel method in propionic acid.Partial substitution of Ni by Cu showed higher activities and selectivities towards syngas products.LaNi0.8Cu0.2O3 was the most active toward the CH4 and CO2 conversions,and was selective for syngas products.Temperature-programmed reduction results showed that the addition of Cu facilitates the reduction of Ni3+ to Ni0,which is the main reason for the higher performance of this catalyst. 相似文献