CeO2中晶格氧直接部分氧化甲烷制取合成气的研究

介绍了一种合成气制取的新方法-熔融盐中用晶格氧直接部分氧化甲烷制取合成气技术,对该技术的概念进行了阐述.以CeO2为氧载体,对反应过程进行了热力学分析,结果表明以CeO2中晶格氧直接部分氧化甲烷制合成气是可行的.在固定床石英反应器中对非熔融盐体系下的氧载体进行了性能评价,并用XRD技术进行了氧载体的表征.在750～900 ℃温度范围内,分别对(0.462×104)/h,(0.924×104)/h,(1.386×104)/h三种空速进行了实验,同时对产物气中n(H2)/n(CO)进行了考察,结果表明,(0.924×104)/h的空速和900 ℃的温度比较适于合成气的制取,失去晶格氧的CeO2-x有着很好的氧再生能力.     

稀土在甲烷部分氧化制取合成气中的应用研究

稀土（La,Ce,Pr,Nd等）通常可以作为催化剂载体、助剂或与其它元素形成固溶体,成为催化剂的重要组成部分。文中系统地介绍了稀土在甲烷部分氧化（CPOM）制取合成气中的相关应用,重点分析了稀土作为催化剂载体、助剂、固溶体等在催化部分氧化制取合成气中的应用,并对其在CPOM中未来前景做出展望。     

稀土基催化材料用于含氯废气催化燃烧的研究进展

针对有毒有害的含氯挥发性有机化合物废气的催化氧化脱除,从稀土氧化物(Ce和La)出发,以饱和含氯代烃(二氯甲烷,二氯乙烷等)和不饱和氯代烃(氯苯,氯乙烯)为模型反应;详细分析了稀土修饰(Ce,La)或以稀土为主的催化剂(CeO_2,La MnO_3)对氯代烃催化燃烧的影响。以催化剂表面的酸性中心和氧化还原性能为主线,分析了二者在氯代烃催化燃烧反应过程中的作用,酸中心与催化剂CO选择性、积碳相关;而多氯副产物的生成和分布则受催化剂氧化性能的影响。在此基础上提出氯代烃的催化燃烧催化剂的设计思路,结合氯代烃分子结构差异,调控催化剂表面酸性中心和氧化还原性能之间的匹配,提高催化剂的低温反应活性、兼顾含碳(氯)副产物的选择性、避免催化剂积碳、氯中毒的现象,增加催化剂的稳定性。     

晶格氧部分氧化甲烷制合成气及其氧扩散行为研究

介绍了一种在熔融盐中利用金属氧化物的晶格氧部分氧化甲烷制合成气的新方法。以NiO为氧载体对其部分氧化甲烷的氧扩散行为进行了初步研究。利用XRD和GC等分析手段,在自行设计的氧扩散行为研究反应器中对熔融盐体系和产物气进行了分析研究。结果表明,在800℃的碳酸熔融盐中,CH4通过不含NiO氧载体的熔融盐层时H2、CO浓度仅为13.67%和20%,而通过含NiO氧载体的熔融盐层时H2、CO浓度明显增至45.9%和24.5%;实验表明NiO能够提供出自身晶格氧把CH4部分氧化成n(H2)/n(CO)接近理论值2的合成气;NiO在熔融碳酸盐体系中虽有少量溶解,但主要不以离子化形式扩散氧,而是CH4与NiO分子间发生气固反应占主导,在这一过程中NiO分子中晶格氧是甲烷部分氧化的活性氧物种。     

钼基催化剂技术发展现状

钼基催化剂广泛用于原油加氢、加氢脱硫,氨氧化丙烷为丙烯腈,气相催化氧化丙烯醛为丙烯酸,1-丁烯氧化脱氢生产1,3-丁二烯,从合成气生产乙醇或混合醇,甲烷干式重整,催化热解含碳气体生产碳纤维或纳米碳管,煤液化或气化和含氮氧化物废气净化等。     

Ni/M_xO_y/CeO_2-ZrO_2(M=Cu,Ba,Al)复合催化剂的制备及其甲烷部分氧化性能

首先采用柠檬酸络法制备了系列Mx Oy/CeO2-ZrO2(M=Cu,Ba和Al)固溶体载体,然后浸渍活性组分Ni,制得系列Ni/Mx Oy/CeO2-ZrO2复合催化剂。考察了掺杂助剂元素(Cu,Ba和Al)对CeO2-ZrO2固溶体结构和负载Ni催化剂的甲烷部分氧化生成合成气催化性能的影响。采用氮气物理吸附,X射线粉末衍射(XRD),氢-程序升温还原(H2-TPR),扫描电子显微镜(SEM),氨-程序升温脱附(NH3-TPD)和热重(TG)等技术对反应前后催化剂的理化性质进行表征。甲烷部分催化氧化表明,催化剂的活性顺序为Ni/Al2O3/CeO2-ZrO2Ni/BaO/CeO2-ZrO2Ni/CeO2-ZrO2Ni/CuO/CeO2-ZrO2。催化剂表征结果表明,掺杂助剂元素后复合载体的主要结构仍然为CeO2-ZrO2固溶体;掺杂的助剂Ba和Al能和CeO2-ZrO2固溶体产生较强的相互作用,生成Mx Oy/CeO2-ZrO2三元复合固溶体载体,并使复合载体的比表面积增大,其中掺杂Al的效果最为明显,能使CeO2-ZrO2固溶体载体颗粒细化,表面结构更丰富,从而有利于活性组分Ni的分散;虽然掺杂Al使载体的表面酸性略有增强,但是Ni/Al2O3/CeO2-ZrO2复合催化剂仍表现了最高的活性和良好的稳定性。掺杂助剂Cu后,Cu与活性组分Ni之间的"氢溢流"效应增强了催化剂中Ni的还原性,生成的Cu0与Ni0之间产生的相互作用导致CuNi合金的生成,减少了Ni0活性中心的数目,导致该催化剂对甲烷部分氧化的活性下降。     

掺杂镧对Ni-Si甲烷裂解催化剂性能影响的研究

采用溶胶-凝胶法制备了Ni-Si催化剂,采用XRD,SEM,HRTEM等技术对催化剂的结构与物性进行了表征,并在微型固定床反应器中考察了甲烷的催化裂解性能,同时考察了稀土La丑对催化剂的甲烷催化裂解性能的影响.结果表明,掺杂稀土La提高了催化剂结晶度,促进了活性中心Ni的表面偏析,同时有利于产物碳物在Ni颗粒表面的扩散和径向迁移,促进均匀细长碳纳米管的形成,提高了催化剂的甲烷催化裂解活性和热稳定性,750℃时氢气生成率达90%,700℃下老化12 h后仍具有较高的催化裂解活性.     

尖晶石型Co0.7Ce0.3Co2O4催化剂的制备及其甲烷催化燃烧性能的研究

采用共沉淀法、溶胶凝胶法和溶液燃烧法制备了一系列Co0.7Ce0.3Co2O4催化剂,研究了制备办法对催化剂甲烷催化燃烧反应性能的影响,并运用XRD、BET和TPR等技术对催化剂进行了表征.结果表明,共沉淀法制备的Co0.7Ce0.3Co2O4催化剂有较好的催化活性和热稳定性,与溶胶凝胶法和溶液燃烧法制备的Co0.7Ce0.3Co2O4催化剂相比,共沉淀法制备的Co0.7Ce0.3Co2O4催化剂有较高的晶格畸变率和比表面积、较大的孔径和孔容、较小的品粒度、较强的氧活动性和较低的甲烷催化燃烧反应的表观活化能.     

合成气制甲醇催化剂的探究新进展

利用合成气制备甲醇是代替石油的高效清洁能源,合成气制甲醇没有工业化的原因是催化剂的选择性较差。探究合成气制甲醇催化剂的研究状况,由催化剂的种类、催化剂制备工艺、助剂的作用、载体几个方面出发分析其结构与性能。超声辅助浸渍法、脉冲电沉积技术、共浸渍法、乙醇诱导的方法、共沉淀法、超声-等离子体联合法等工艺的改进或结合更有利于活性组分的分散和形成更加细小的粒径颗粒。催化剂利用合适的工艺方法和良好反应器可以获得更好的催化效果,实现合成气制备甲醇的产业化推广,解决能源匮乏问题。     

水含量对醇盐水解制备LaMnAl11O19-δ催化剂结构及其甲烷燃烧性能的影响

采用溶胶凝胶法中的金属醇盐水解技术制备LaMnAl11O19-δ六铝酸盐催化剂,通过X射线衍射、差热-热重、扫描电镜和比表面积分析等实验技术及甲烷燃烧,对催化剂的结构和性质进行了考察.主要考察了金属醇盐水解时加入不同含量的水对催化剂结构以及对甲烷催化燃烧活性的影响.结果表明,催化剂在1200C焙烧后可以形成完整的六铝酸盐晶型,同时具有较高的催化性能和高温稳定性.水含量对催化剂的性能有较大的影响,水含量较大时催化剂的比表面积和活性明显下降.当水和醇盐的摩尔比为1.5时,所制备的LaMnAl11O19-δ具有较大的比表面积和催化活性.     

甲烷部分氧化的热力学模拟研究

甲烷部分氧化制备合成气对于提高天然气的利用价值具有重要的意义。甲烷部分氧化反应是一个非常复杂的反应体系。反应涉及部分氧化（主反应）、燃烧、重整、水煤气变换、积炭等。使用Aspen Plus和HSC Chemistry软件对甲烷部分氧化制备合成气过程进行热力学模拟计算。考察了温度、压力和CH4/O2比对CH4转化率、氢和CO选择性的影响。同时对甲烷部分氧化反应热力学平衡产物组成和积炭副反应进行了热力学计算分析。研究结果表明,随反应温度的升高,压力的减小,CH4的转化率和CO与H2的选择性均呈上升趋势。反应温度在300℃时就有相当多的积炭生成,在550℃积炭量达到最大,随后又随温度上升,积炭量逐渐减少,在900℃以上无积炭产生。     

Synthesis gas production using oxygen storage materials as oxygen carrier over circulating fluidized bed

A novel process for synthesis gas production over Circulating Fluidized Bed （CFB） using oxygen storage materials as oxygen carder was reported. First, oxygen in the air was chemically fixed and converted to lattice oxygen of oxygen storage materials over regenerator, and then methane was selectively oxidized to synthesis gas with lattice oxygen of oxygen storage materials over riser reactor. The results from simulation reaction of CFB by sequential redox reaction on a fixed bed reactor using lanthanum-based perovskite LaFeO3 and La0.8Sr0.2Fe0.9CO0.1O3 oxides prepared by sol-gel, suggested that the depleted oxygen species could be regenerated, and methane could be oxidized to synthesis gas by lattice oxygen with high selectivity. The partial oxidation of methane to synthesis gas over CFB using lattice oxygen of the oxygen storage materials instead of gaseous oxygen should be possibly applicable.     

Effect of calcination temperature and reaction conditions on methane partial oxidation using lanthanum-based perovskite as oxygen donor

We investigated the effect of calcination temperature, reaction temperature, and different amounts of replenished lattice oxygen on the partial oxidation of methane （POM） to synthesis gas using perovskite-type LaFeO3 oxide as oxygen donor instead of gaseous oxygen, which was prepared by the sol-gel method, and the oxides were characterized by XRD, TG/DTA, and BET. The results indicated that the particle size increased with the calcination temperature increasing, while BET and CH4 conversion declined with the calcination temperature increasing using LaFeO3 oxide as oxygen donor in the absence of gaseous oxygen. CO selectivity remained at a high level such as above 92%, and increased slightly as the calcination temperature increased. Exposure of LaFeO3 oxides to methane atmosphere enhanced the oxygen migration of in the bulk with time online owing to the loss of lattice oxygen and reduction of the oxidative stated Fe ion simultaneously, The high reaction temperature was favorable to the migration of oxygen species from the bulk toward the surface for the synthesis gas production with high CO selectivity. The product distribution and evolution for POM by sequential redox reaction was determined by amounts of replenished lattice oxygen with gaseous oxygen. The optimal process should decline the total oxidation of methane, and increase the selectivity of partial oxidation of methane.     

Influence of Supports on Catalytic Performance and Carbon Deposition of Palladium Catalyst for Methane Partial Oxidation

The catalytic performance of methane partial oxidation was investigated on Pd/CeO2-ZrO2 and Pd/α-Al2O3 catalysts.The catalysts were characterized by XRD,Raman spectra,and TG-DTA techniques.The results show that CeO2-ZrO2 support is more advantageous for the catalytic activity and stability of catalysts compared to α-Al2O3.TG-DTA and Raman spectra results indicated that carbon deposited on the catalysts was in the form of graphite,which is the main reason for the deactivation of catalysts after a 24-hour reaction.Moreover,CeO2-ZrO2 had positive effect on inhibiting carbon deposition.     

Catalytic performance of cerium iron complex oxides for partial oxidation of methane to synthesis gas

The cerium iron complex oxides oxygen carrier was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carder could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carders were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carrier： the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species （bulk lattice oxygen） that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction condition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.     

高性能自支撑氧催化电极基底材料的研究进展

在“碳达峰”和“碳中和”的时代背景下,电解水、金属空气电池、燃料电池等清洁能源技术由于具有能量效率高、安全性好、结构简单和清洁环保等优点受到广泛关注.然而,发生在氧催化电极上的关键反应——氧还原反应（ORR）和氧析出反应（OER）具有缓慢的动力学,很大程度上阻碍了其商业化应用.传统氧催化电极存在合成过程繁琐、可控性低、均一性差、成本高和载体催化剂易团聚等问题,限制了其催化性能.自支撑氧催化电极的高催化活性位点、高稳定性等优势可以完美解决传统电极面临的问题.本文介绍了自支撑氧催化电极基底材料的研究进展以及合成方法,并讨论了影响自支撑氧催化电极ORR/OER催化性能的因素,最后对自支撑氧催化电极未来的研发方向和发展趋势提出展望.     

Effect of Lanthanum on Catalytic Growth of Carbon Nanotubes from Methane over Nickel-Aluminum Catalyst

The synthesis of carbon nanotubes (CNTs) from methane decomposition by Ni-La-Al (Ni/La/Al = 10: 1:9) and Ni-Al (Ni/A1 = 1:1 ) catalysts at 1023 K was studied.Catalysts were prepared by a co-precipitation method.During the methane decomposition, a part of gases at the exit of the reactor was analyzed by gas chromatography.The experimental results show that doping La into Ni-A1 catalyst improves the catalytic lifetime and the yields of CNTs in the methane decomposition.Some characteristics of CNTs were investigated by TEM and XRD.The analyses show that CNTs deposited on the Ni-La-A1 catalyst have obvious thinner walls, less bend structures and better graphitization than the sample grown over Ni-Al.These results indicate that the introduction of lanthanum into the nickel-aluminum catalyst leads to significant changes in the morphology and microstructures of the CNTs.     

Cerium (Ⅳ) oxide nanocomposites:Catalytic properties and industrial application

This review article provides a new insight on the application of cerium oxide(CeO_2)-metal oxide nanocomposites as catalyst with enhanced reducibility and improved oxygen(O_2) storage capacity,especially in the varying chemical reaction processes including combustion,oxidation,epoxidation and redox.The CeO_2-metal oxide interaction plays an important role in controlling particle size,O_2 availability and coke resistance properties of the catalyst.Strong metal oxide-CeO_2 interaction also assists in generating small and highly dispersed particles,resists sintering of catalyst particles during the catalysis process,and consequently improves the O_2 availability of the catalyst.Indeed,CeO_2 not only provides an active support to heterogeneous catalyst,but also creates a new active site at the metal-support interface to produce stronger nanoparticle bonding through the surface O_2 vacancy.This consequently produces a heterogeneous catalytic system with promising reaction rate and catalytic stability in many industrial applications such as CO_2 hydrogenation,CO oxidatio n,biodiesel productio n,gas reduction,photocatalytic and methane steam reforming.