甲烷部分氧化制合成气的研究进展

综述了近年来甲烷部分氧化制合成气的催化剂，反应机理及活性中心的研究进展及反应中存在的主要问题。     

甲烷催化部分氧化制合成气的研究进展

文章叙述了甲烷催化部分氧化制合成气研究的进展情况。介绍了两种主要的反应机理：间接反应机理和直接反应机理;对负载型镍系催化剂的研究现状进行了叙述,并简单介绍了非负载型催化剂;另外还对固定床、流化床、膜反应器以及一些新开发的反应器的特点进行了讨论。     

甲烷部分氧化制合成气镍基催化剂的研究进展

镍基催化剂是甲烷部分氧化制合成气研究最多、最有前途的催化剂.相对其他催化剂它具有较好的抗积碳性、稳定性且价格低廉.如何提高甲烷在部分氧化反应中的转化率是当前备受关注的重要研究课题.从镍基催化剂的载体、助剂、制备方法等方面的研究进行了综述.     

整体型催化剂在天然气部分氧化中的研究进展

由于热量散失和均相反应使直接部分氧化甲烷很难控制,本文介绍了整体型催化剂在天然气部分氧化中的应用,使用整体型催化剂反应可在大空速下自热进行,基本实现干氧化。     

甲烷部分氧化制合成气反应的研究

用粒度为5mm的α－Al2O3、β-Al2O3、γ-Al2O3为载体，用浸渍法制备了10％（质量）Ni基催化剂。在固定床流动反应器中，在反应温度500－850℃，大空速和不同的CH4／O2摩尔比下，测定了该催化剂用于甲烷部分氧化制合成气的活性和CO选择性。500℃用H2对催化剂还2h后，进行活性测试结果,10%Ni／β-Al2O3、Ni／γ-Al2O3对POM反应无活性，只有10％Niα－Al2O3对POM反应有活性。TPR测试结果表明，这是由于10％Ni／β-Al2O3和Ni／γ-Al2O3催化剂在700℃以下未被还原所致。另外，合成气的生成速率和CO选择尾均随反应温度和空速的增大而增大，并在CH4／O2摩尔比2时有最大值。     

甲烷空气部分氧化制合成气喷动床反应器的研究

On the basis of hydrodynamic and scaling-up studies, a pilot-plant-scale thermal spouted bed reactor (50 mm in ID and 1500 mm in height) was designed and fabricated by scaling-down cold simulators. It was tested for making syngas via catalytic partial oxidation (CPO) of methane by air. The effects of various operating conditions such as operating pressure and temperature, feed composition, and gas flowrate etc. on the CPO process were investigated. CH4 conversion of 92.20％ and selectivity of 92.3% and 83.30/0 to CO and H2, respectively, were achieved at the pressure of 2.1 MPa. It was found that when the spouted bed reactor was operated within the stable spouting flow regime, the temperature profiles along the bed axis were much more uniform than those operated within the fixed-bed regime. The CH4 conversion and syngas selectivity were found to be close to thermodynamic equilibrium limits. The results of the present investigation showed that spouted bed could be considered as a potential type of chemical reactor for the CPO process of methane.     

催化部分氧化甲烷制合成气的平衡热力学研究

The catalytic partial oxidation of methane to syngas (CO H2) has been simulated thermodynamically with the advanced process simulator PRO/Ⅱ. The influences of temperature,pressure,CH4/O2 ratio and steam addition in feed gas on the conversion of CH4 selectively to syngas and heat duty required were investigated, and their effects on carbon formation were also discussed. The simulation results were in good agreement with the literature data taken from a spouted bed reactor.     

甲烷部分催化氧化合成甲醇和甲醛

本文综述了由甲烷部分催化氧化制甲醇和甲醛研究中所用催化剂的制备条件及催化反应条件,并对用于该反应的催化剂开发和最佳合成工艺条件的选择指出了方向。     

甲烷部分氧化制合成气催化剂的研究进展

综述了甲烷部分氧化制合成气的研究意义和现状，从金属活性组分，载体效应，载量选择，助剂添加和制备方法等因素对催化剂活性的影响及研究进行了系统。结合本课题组的研究结果及文献报道，分析了Ni基催化剂的失活特性，并提出使用等离子体技术对Ni基催化剂进行改笥处理，以提高其催化稳定性的技术展望。     

Oscillatory Behavior During the Partial Oxidation of Methane Over Nickel Foils

The study of the partial oxidation of methane over nickel foils has been carried out over a wide range of reactor temperatures (748-930 °C) and feed-gas compositions (Ar/CH₄/O₂), ranging from 30:29:1 to 30:12:18 cm³ min^-1 at atmospheric pressure. The product formation shows pronounced oscillations. A modified thermocouple was designed to measure the temperature while the interposed nickel foil worked as a catalyst. The oscillations have been attributed to the cyclic reduction and oxidation of the nickel surface in the specific reaction environment at elevated temperatures.     

甲烷部分氧化制合成气催化剂的研究进展

甲烷部分氧化（POM）反应制合成气是化学利用甲烷的有效途径之一。研究表明,甲烷部分氧化反应的工艺有能耗低和反应速率较快等优点,而且所得的H2和CO的比例适于合成甲醇等工业化学品。在该工艺过程中,所需反应容器体积小,反应效率高,可大幅度降低制备合成气的成本。开发POM反应的高效催化剂是进一步提高反应效率、实现工业化的关键途径,因此,是当前国际催化领域研究的热门课题之一。本文主要介绍了传统的金属负载型催化剂和金属氧化物催化剂用于POM反应的研究进展。     

天然气催化部分氧化制备合成气的进展

综述了天然气催化部分氧化制备合成气的国内外技术进展情况，包括固定床催化部分氧化、两段转化法、膜反应器工艺、流化床工艺等，指出流化床工艺和膜反应器工艺最合理。     

Support Effect in Supported Ni Catalysts on Their Performance for Methane Partial Oxidation

Supported nickel catalysts were prepared by impregnation of La₂O₃, MgO and ZrO₂ substrates and tested in the partial oxidation of methane to synthesis gas at atmospheric pressure. Nickel interacted strongly with La₂O₃ forming a deficient LaNiO_3- perovskite structure upon calcination. Upon reduction at 973 K, the Ni/La₂O₃ catalysts that resulted were highly active and selective for syngas production. By contrast, a separate and readily reducible NiO phase was formed on the ZrO₂ support. Because the interaction of metallic nickel particles on ZrO₂ is weak, the catalysts underwent deactivation by sintering of metal particles during on-stream operation as confirmed by photoelectron spectroscopy. The relatively high activity of the Ni/MgO systems was associated with the formation of a highly stable cubic Ni-Mg-O solid solution, in which nickel remains highly dispersed during the methane partial oxidation reaction.     

Further Studies on Oscillations over Nickel Wires During the Partial Oxidation of Methane

Oscillatory reactions over nickel wires during the partial oxidation of methane were investigated in a tubular continuous flow reactor made of quartz at atmospheric pressure. A modified thermocouple was designed to measure the temperature while the interposed nickel coil worked as a catalyst. Significant effects on the oscillations were observed by varying the system temperature and the feed gas composition, and by cutting off one of the reactant gases temporarily.     

Rh负载的泡沫独石上甲烷部分氧化的基元反应动力学模拟

Rh负载的泡沫独石催化剂上进行的甲烷催化部分氧化反应,能够在自热、毫秒级接触的条件下达到接近平衡的转化率和选择性.采用CH4在Rh催化剂上发生部分氧化反应的基元反应动力学网络结合平推流模型,进行了一维的反应流模拟,揭示了毫秒级催化反应的反应历程.CH4/O2摩尔比在1.7～2.3,外界温度550～800℃的范围内,模拟结果和实验结果能够很好地吻合.模拟不仅给出了催化剂床层内气相和表面物种的变化情况,还揭示了催化剂有效内表面积和甲烷吸附能力对反应的影响,发现一定程度下有效内表面积的增加和甲烷吸附能力的增强,能够大幅度地提高反应的转化率和选择性.     

甲烷部分氧化反应的磷钨酸催化剂研究

以磷钨酸为催化剂和氧化剂,进行了无氧条件下的甲烷气固相部分氧化的实验研究,考察了磷钨酸催化剂的制备条件、载体影响以及反应温度对甲烷部分氧化反应的影响等.磷钨酸催化剂可有效催化甲烷部分氧化反应,甲烷首先转化生成醋酸甲酯,醋酸甲酯水解生成甲醇.制备的催化剂以SiO2为载体,采用载体质量15%(wt)的磷钨酸水溶液回流浸渍4 h、120℃干燥2 h、300℃焙烧4 h制得.甲烷部分氧化反应在0.10 MPa、267～280℃进行,甲烷转化率为26.61%,目的产物收率25.82%.     

甲烷非催化部分氧化制乙炔和合成气过程的实验研究

通过探头取样和四极杆质谱在线测量甲烷、氧气和乙炔等组分的浓度分布,考察了氧气/甲烷(甲烷+乙烷/丙烷)摩尔比、气体预热温度及原料气中添加乙烷和丙烷对甲烷非催化部分氧化制乙炔和合成气的影响. 结果表明,随轴向距离增加,乙炔浓度先增大后减小,存在最大值;随氧气/甲烷(甲烷+乙烷/丙烷)摩尔比增加,乙炔选择性下降;升高混合气体预热温度产物中乙炔浓度增大,620℃时最大乙炔浓度为4.52%;添加乙烷和丙烷时产物中乙炔浓度基本不变,但甲烷消耗量下降. 在实验条件下,生成最大乙炔浓度的激冷位置距烧嘴出口的距离约为80 mm.     

基于详细反应机理的甲烷部分氧化制乙炔过程模拟

基于Curran详细反应机理,采用CHEMKIN软件对贫氧条件下的甲烷非催化部分氧化过程进行了模拟. 在预热温度为873 K、氧气/甲烷摩尔比为0.55的工业反应器操作条件下,模拟得到的最大乙炔浓度为7.6%(mol),与工业数据相符. 分析了操作参数对自燃诱导时间和产物浓度的影响. 结果表明,当预热温度为823 K时,最大乙炔浓度为7.8%(mol);1023 K时为8.4%(mol). 乙炔浓度在达到最大值后快速下降,因此必须在最大值时通过淬冷等措施及时终止反应以获得最大乙炔收率.     

天然气部分氧化制合成气的研究进展

综述了天然气部分氧化制合成气的研究进展,包括天然气无催化部分氧化、固定床催化部分氧化、两段转化法、膜反应器新工艺、流化床反应工艺、氧化剂研究、微波辐射加热部分氧化、部分氧化的机理,以及部分氧化工艺的催化剂研究。     

Partial Oxidation of Methane to Synthesis Gas Over Ru-Loaded Y2O3 Catalyst

Ru-loaded Y₂O₃ catalyst was investigated for the partial oxidation of methane to synthesis gas. Ru(0.5 wt%)/Y₂O₃ catalyst afforded a high CH₄ conversion of 27% at a CH₄:O₂ ratio of 5 to give nearly a 1:2 ratio of CO and H₂ with a selectivity of 75% at 873 K. Ru(0.5 wt%)/Y₂O₃ catalyst maintained high catalytic activity over 10 h in the partial oxidation of methane. Carbon deposition of the catalyst surface in the reaction of CH₄ was examined by thermogravimetric analyses, and it was found that no carbon deposition occurred on the Ru(0.5 wt%)/Y₂O₃ catalyst. The synthesis-gas production proceeded basically via a two-step reaction consisting of methane combustion to give H₂O and CO₂, followed by the reforming of methane from CO₂ and steam.