镍基CH4-CO2重整催化剂研究综述

化石燃料的使用,导致大量CO₂温室气体排放,由此引起了一系列环境和气候问题。主要温室气体CO₂和CH₄的处理和利用已迫在眉睫。CH₄-CO₂干重整(DRM)将CO₂和CH₄转化为工业原料气合成气,可以实现2种温室气体的利用。贵金属催化剂对DRM反应表现出优异的催化活性和抗积碳性能,但由于资源有限、价格高,限制了其应用。非贵金属Ni基催化剂的催化活性不仅可以与贵金属相媲美,且来源丰富、价格低,是最有可能被产业化的催化剂之一。但Ni基催化剂存在易烧结和积碳的问题。研究者对Ni基催化剂进行了大量改性工作以提高其催化活性、抗烧结能力和抗积碳能力。为更全面深入认识DRM反应及其Ni基催化剂,首先综述了CH₄-CO₂重整反应的热力学、反应机理和动力学。热力学研究表明,高温低压有利于DRM反应进行;但至今没有适合于所有催化剂统一的反应机理,不同催化剂的反应机理和速控步骤不同。进一步对影响Ni基催化剂性能的...     

CO2吸附强化CH4/H2O重整制氢催化剂研究进展

CO_2吸附强化CH_4/H_2O重整制氢是提供低成本高纯氢气和实现CO_2减排的方法之一。其中,催化剂和吸附剂是该工艺的重要组成部分,其活性与选择性制约了反应速率和产率,寿命长短关系到生产成本。综述了CO_2吸附强化CH_4/H_2O重整制氢催化剂和吸附剂的研究现状及存在的问题,机械混合的催化剂与吸附剂在反应过程中存在吸附产物包覆催化活性位点的问题,导致催化剂活性迅速下降。针对该问题,进一步探讨了不同结构双功能复合催化剂的结构特性、研究现状及其在循环-再生过程中存在的问题,核壳型双功能催化剂具有吸附组分与催化剂组分相对独立、催化组分分散分布和比表面积大等优点,在吸附强化制氢中有进一步研究的潜力。利用双功能催化剂的结构特点,实现反复循环再生过程中催化与脱碳反应的匹配,是推动CO_2吸附强化CH_4/H_2O重整制氢技术工业化发展的关键。     

炭催化富CH4气CO2重整制合成气及动力学研究

以UGI煤气发生炉为基础，在实验室设备装置上模拟气化炉上吹阶段，通入模拟混合气制备合成气，开发了一套新的制备合成气工艺。通过实验研究发现，反应温度和半焦粒度对甲烷转化率具有重要影响。加入水蒸气可以提高炭材料催化剂的稳定性和甲烷转化率，这主要是由于加入水蒸气可以气化半焦表面生成的积碳，同时生成新的活性位给甲烷二氧化碳重整反应提供活性，从而促进甲烷和二氧化碳转化。另外，通过对水蒸气条件下富甲烷气二氧化碳重整动力学研究，得到了炭催化富甲烷气二氧化碳重整的表观活化能为199.7 kJ·mol^-1。     

煤层气转化制合成气Ni基催化剂的研究

采用10%Ni/4%MgO-Al2O3催化剂,在常压固定床反应器上进行CO2重整CH4制合成气反应的研究;系统考察了载体制备方法、MgO含量、焙烧温度及焙烧方式等因素对催化剂性质的影响;并采用N2物理吸附、XRD等检测手段对催化剂进行了表征。结果表明,采用共沉淀法,MgO质量分数为4%,在FAir中550℃下焙烧4 h的10%Ni/4%MgO-Al2O3的催化活性较好,CH4和CO2的转化率可以达到82%和92%。     

太阳能直接驱动CH4和CO2干重整技术进展

随着世界经济的快速发展,能源短缺和环境污染已成为关注焦点,化石燃料的快速消耗使得温室效应持续增强,对全球环境和气候造成了严重影响。利用丰富和清洁的太阳能驱动的方式可以快速靶向供热,在温和条件下将2种主要温室气体(CH₄/CO₂)转化为有价值的合成气,可以大幅降低传统热催化过程所产生的能耗及碳排放。然而,当前太阳能直接驱动干重整制合成气技术距离工业应用仍有一些距离,存在反应分子转化速率低、光能-化学能转化效率低、催化剂易烧结及积碳造成的催化剂失活等问题。针对干重整反应的固有特性以及当前光热研究领域普遍存在的问题,围绕该反应涉及的催化剂制备、载体构筑、反应器及系统搭建与优化,详细介绍了光热干重整反应的研究进展,最后展望了太阳能直接驱动光热催化干重整体系的前景和挑战。     

光催化CO2和CH4重整催化剂研究进展

太阳能驱动的CO₂与CH₄转化为合成气是一种非常有前景的生产可再生燃料的技术，然而太阳能驱动的CH₄重整催化剂存在转化效率低、光生电子与空穴复合速率快及催化剂稳定性差等问题。本文简述了光催化CO₂与CH₄重整的可能机理，包括CO₂和CH₄的吸附、光生电子与空穴的迁移及产物的脱附过程。重点介绍了光催化CO₂和CH₄重整过程中贵金属催化剂、非贵金属催化剂及碳氮化合物等催化剂的研究进展，并总结归纳了各类催化剂的优点与不足。最后，本文探讨了光催化转化CO₂与CH₄制合成气研究领域未来可能的发展方向：开发设计高效的光催化剂提高反应效率；通过密度泛函理论计算及高端表征技术探究催化机理。     

CH4-CO2低温等离子体重整制合成气的研究

为了探究CH₄-CO₂低温等离子体重整制合成气的反应特性,考察了添加气体、放电电压、放电频率、CH₄与CO₂物质的量比和原料气流量对重整反应的影响,在优化单纯等离子体作用下CH₄-CO₂重整反应条件的基础上,开展了等离子体与NiO-CeO/TiO₂-MgO催化剂协同转化CH₄-CO₂的实验。结果表明,实验体系中添加Ar或N₂,放电引发的亚稳态Ar^*或N₂激发态粒子,可促进反应物转化和目标产物生成,且Ar对CH₄-CO₂重整反应的促进作用优于N₂;在单纯等离子体作用、Ar体积分数25%,放电电压17.0 kV,放电频率9.0 kHz, CH₄与CO₂物质的量比1∶2,气体总流量60 mL/min条件下,CH_4<...     

CH4／CO2催化重整制合成气的研究进展

甲烷和二氧化碳反应催化重整制取合成气有效利用两种温室气体,对改善人类生存环境和缓解能源危机具有重要意义,近年来引起广泛研究者的关注。本文参阅了许多有关甲烷与二氧化碳催化重整制合成气的相关文献,概述了近年来在此研究中催化剂的选择、载体的作用、助剂的影响及催化剂积炭等方面的研究进展。     

CH4与CO2催化重整制合成气研究进展

本文综述了CH4与CO2重整制合成气的研究进展,对重整催化剂、重整反应机理及重整动力学进行了评述。     

CO2电催化还原制合成气研究进展及趋势

可再生电能驱动CO₂电催化合成化学品或燃料,具有反应条件温和、产物选择性可调且可利用分布式可再生能源优势。合成气作为一类重要的化工原料气,可制备甲醇、乙醇、烯烃等大宗化学品,是CO₂电催化转化的重要途径,如何高电流密度、高选择性且精准调控碳氢比例(CO/H2)是需要解决的关键科学技术难题。本文从提升电流密度和效率、拓宽合成气比例角度出发,综述了CO₂电催化还原制合成气的最新研究进展,包括电极材料设计、电解液开发、电解槽结构创新等;论述了利用原位表征和理论模拟(DFT、MD)方法对CO₂电催化还原制合成气反应机理的研究进展。在此基础上,提出可通过催化剂多级形貌调控、多活性位点设计、CO₂捕集与转化系统集成、CO₂还原与阳极反应耦合等途径,提升CO₂电催化还原制合成气效率的策略。最后,探讨和展望了实现CO₂电催化还原制合成气工业化的挑战和问题。     

Ni-Co bimetallic catalyst for CH4 reforming with CO2

A co-precipitation method was employed to prepare Ni/Al₂O₃-ZrO₂, Co/Al₂ O₃-ZrO₂ and Ni-Co/Al₂O₃-ZrO₂ catalysts. Their properties were characterized by N₂ adsorption (BET), thermogravimetric analysis (TGA), temperature-programmed reduction (TPR), temperature-programmed desorption (CO₂-TPD), and temperature-programmed surface reaction (CH₄-TPSR and CO₂-TPSR). Ni-Co/Al₂O₃-ZrO₂ bimetallic catalyst has good performance in the reduction of active components Ni, Co and CO₂ adsorption. Compared with mono-metallic catalyst, bimetallic catalyst could provide more active sites and CO₂ adsorption sites (C + CO₂ = 2CO) for the methane-reforming reaction, and a more appropriate force formed between active components and composite support (SMSI) for the catalytic reaction. According to the CH₄-CO₂-TPSR, there were 80.9% and 81.5% higher CH₄ and CO₂ conversion over Ni-Co/Al₂O₃-ZrO₂ catalyst, and its better resistance to carbon deposition, less than 0.5% of coke after 4 h reaction, was found by TGA. The high activity and excellent anti-coking of the Ni-Co/Al₂O₃-ZrO₂ catalyst were closely related to the synergy between Ni and Co active metal, the strong metal-support interaction and the use of composite support.     

甲烷二氧化碳催化重整催化剂研究进展

甲烷二氧化碳催化重整反应由于对于环境保护与综合利用资源具有重大意义,近年来得到了研究者的广泛重视。本文参阅众多文献,概述了二氧化碳、甲烷催化重整反应的研究动态。着重介绍了催化剂活性组分的选取,载体影响和助剂作用等方面的最新进展。     

Role of support in reforming of CH4 with CO2 over Rh catalysts

The reforming of CH₄ with CO₂ over supported Rh catalysts has been studied over a range of temperatures (550–1000 K). A significant effect of the support on the catalytic activity was observed, where the order was Rh/Al₂O₃>Rh/TiO₂>Rh/SiO₂. The catalytic activity of Rh/SiO₂ was promoted markedly by physical mixing of Rh/SiO₂ with metal oxides such as Al₂O₃, TiO₂, and MgO, indicating a synergetic effect. The role of the metal oxides used as the support and the physical mixture may be ascribed to the promotion in dissociation of CO₂ on the surface of Rh, since the CH₄ + CO₂ reaction is first order in the pressure of CO₂, suggesting that CO₂ dissociation is the rate-determining step. The possible model of the synergetic effect was proposed.     

Shell煤气化制合成气与甲烷重整二氧化碳耦合研究

为了优化化工合成过程,节约资源,减排温室气体CO2,采用Aspen Plus软件,基于Gibbs自由能最小原理,对Shell煤气化制合成气与CH4、CO2耦合过程进行模拟。分析了CH4、CO2、O2三者之间的比例对于重整合成气的影响。结果表明:当CO2/CH4体积比为1.02时,O2/CH4体积比为0.1时,得到氢碳比为0.829。通过灵敏度分析了O2量和压力对反应的影响,O2量的增加,反应温度升高,有利于耦合反应的进行;压力的增加,不利于耦合反应,但是加压可以提高生产强度,因此一般都选用加压条件下进行。     

镍负载柱撑蛭石催化甲烷与二氧化碳重整制合成气

用浸渍法制备12Ni-PCVMT催化剂,考察了制备方法对其结构及甲烷干重整催化性能的影响。结果表明,在常压,750℃条件下,经过17 h在线评价后,12Ni-PCVMT催化剂具有高的反应活性和稳定性,具有较好的镍分散性、粒径分布更均匀,比表面积较大,从而具有更好的Ni抗烧结能力及抗积炭性。     

Modification of alumina support with TiO2-P25 in CO2 reforming of CH4

Catalyst activity and stability for CO₂ reforming of CH₄ depends specifically upon the support and the active metal. A side reaction of dry reforming of methane is the decomposition to carbon that covers the Ni particles causing catalyst deactivation. Hence, an appropriate combination of Ni with support is needed to allow for long term stable operation. In this paper, CO₂ reforming of CH₄ is studied by investigating the effect of addition of TiO₂-P25 separately to γ-Al₂O₃ and α-Al₂O₃ supports used for nickel based catalyst. The reforming reactions are performed using (CO₂:CH₄) feed ratio of 1:1 and reaction temperature range of 500–800 °C. Both fresh and used catalysts are characterized by SEM and TGA techniques. It is found when α-Al₂O₃ support is modified with 20 wt% TiO₂-P25, the catalyst activity and stability is enhanced. The conversion rates of CH₄ and CO₂ without and with 20 wt% TiO₂-P25, respectively, are changed from 72.3% to 76.7% and 73.3% to 81.2%, respectively, and, most importantly, carbon formation is reduced from 28.1 to 12.8, respectively. However, when γ-Al₂O₃ support is modified with TiO₂-P25, the catalyst activity is enhanced with simultaneous increase in carbon formation.     

Syngas production via CO2 reforming of methane using Co-Sr-Al catalyst

The effect of addition of strontium in Co based catalysts during CO₂ reforming of methane was investigated in the temperature range 500–700 °C. The Co/γ-Al₂O₃ supported catalysts with strontium as a promoter (0–2.25 wt%) were prepared by incipient wet impregnation method. Numerous techniques such as N₂ adsorption–desorption isotherm, H₂ temperature-programmed reduction (TPR), temperature-programmed desorption (TPD), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Transmission Electron Microscopy (TEM), pulse chemisorption and temperature-programmed oxidation (TPO) were applied for characterization of fresh and spent catalysts. The results of characterizations and catalyst activity test revealed that introduction of Sr in Co/γ-Al₂O₃ catalyst had significant effect on stability and coke suppression. The Sr addition improves the metal–support interaction as well as enhances the Lewis basicity of the catalyst. The improvement in basicity helps the chemisorption and dissociation of CO₂ over the catalyst which in turn reduces carbon deposition.     

Analyzing enhancement of CO2, reforming of CH4, in Pd membrane reactors

It is demonstrated that H₂, removal through Pd foil membranes can enhance the CO₂, reforming of CH₄. At 550°C and low flows over Pt/γ -Al₂O₃, pellets, conversions were twice that of a conventional reactor, while H₂O formation was suppressed, resulting in H₂/CO effluent ratios of 1.0. Larger sweep flows enhanced the reaction somewhat, and the replacement of Pt/γ -Al₂O₃, with Pt/ZrO₂ mitigated catalyst deactivation in H₂-poor operating environments. A quantitative correlation was established between reaction enhancement and the overall H₂ removal to production ratio. Based on this correlation, a simple membrane reactor equilibrium model was developed for comparison against experimental data. Subsequently, a unique and useful “on-the-fly” method of gauging membrane limitations, catalyst limitations, and modes of deactivation within a membrane reactor was demonstrated.     

铁基氧载体化学链CO2重整CH4方法制备合成气

提出一种铁基氧载体（Fe₃O₄/FeO）化学链CO₂重整CH₄方法制备合成气。为评价该系统的性能,采用Aspen Plus软件对其进行过程模拟和热力学分析。以CH₄转化率、CO₂转化率、能源利用效率和产气氢碳比（H₂/CO）为评价指标,得到系统的优化运行条件,并研究各操作参数（包括各反应器的温度和压力、氧载体甲烷比和CO₂甲烷比）对系统性能的影响。结果表明：当系统处于优化工况时,得到CH₄转化率为97.91%、CO₂转化率为32.76%、能源利用效率为93.77%及产气氢碳比为0.93。该系统能有效利用CO₂和CH₄这两种温室气体获得较低氢碳比的合成气,利于二甲醚的高效合成。