The conversion of methane to ethylene and ethane with near total selectivity by low temperature (< 610 ° C) oxydehydrogenation over a calcium-nickel-potassium oxide catalyst

The catalytic oxidative coupling of methane to C₂, C₃ and C₄ paraffins and olefins has been accomplished with close to 100% selectivity at methane conversions of about 10% per pass. Essentially no carbon oxides are formed and the mechanism appears to be a surface catalyzed reaction. Temperatures of < 600 ° C are used and the presence of steam is important. The catalyst comprises a ternary mixture of calcium, nickel and potassium oxides. Method of preparation and composition of the catalyst are critical for its performance. Presence of a carbidic carbon on the catalyst surface may be important.     

Direct catalytic conversion of methane

Processes are being developed for the direct catalytic oxidative conversion of methane to higher hydrocarbons and oxygenates. The role of the catalyst in generating methyl radicals is established, and subsequent gas-phase reactions are well understood. However, the role of several catalyst surface species remains a subject of interest. Application of present process technology using the most promising catalysts shows that direct methane conversion is not yet competitive with conventional processes. Increased yields of desirable products using new process configurations are required to obtain an economically viable process.     

Experimental investigation of the catalytic cracking of methane over a supported Ni catalyst

TGA experiments on the catalytic cracking of methane and methane diluted with hydrogen over a 5 wt% Ni/γ‐alumina catalyst at 500°C and 1 and 10 bar are described. Carbon deposition on the catalyst, as expressed in specific weight of carbon, varies with time. Eventually, the deposition stops because of deactivation. The specific weight at this point depends on the hydrogen partial pressure and there is also a weak dependence on the degree of contact between catalyst particles. A model based on assuming carbon deposition proceeds through whisker formation and growth, and deactivation occurs through encapsulation adequately describes the experimental observations up to 20 vol% hydrogen in the feed.     

硫化处理对负载钯催化剂甲烷低温催化燃烧性能的影响

采用浸渍法制备氧化硅负载钯催化剂,考察硫化气氛和硫化时间对催化剂性能的影响,并采用XRD对催化剂进行表征。结果表明,硫化后形成的Pd4S物种可以提高催化剂抗硫中毒性能,同时催化剂表面的SPd4S/SPd对催化活性有重要影响,改变硫化气氛和硫化时间可以调节Pd4S物种的形成和SPd4S/SPd。     

Monte Carlo simulation studies of the catalytic combustion of methane

A Monte Carlo (MC) simulation is carried out of the catalytic oxidation of methane based on the pseudo-Langmuir-Hinshelwood (LH) mechanism proposed by Iglesia et al., that attempts to interpret the behavior of this reaction, which from experiments is assumed to be of the Mars-van Krevelen type. The results interpret reasonably some experimental findings (reaction order with respect to H₂O, CH₄, activity and structural sensitivity) if certain criteria based on the experiment and some laboratory data for the kinetic and thermodynamic parameters from the literature are considered.     

高比表面积Pd纤维催化剂的制备及其甲烷催化燃烧性能

制备了PdO/CeO2/γ- Al2 O3/Al2 O3 - SiO2纤维催化剂,考察了CeO2掺杂对催化剂甲烷催化燃烧活性的影响.结果表明,掺杂质量分数0.05％ CeO2,催化剂活性最好,甲烷完全转化温度为385℃.BET比表面积测定结果显示,γ- Al2 O3的加入极大提高了纤维的比表面积;氧气程序升温脱附实验结...     

硫化处理对钯锆纤维催化剂甲烷低温催化燃烧性能的影响

采用胶体喷吹成型法制备钯锆-γ-氧化铝纤维催化剂。将催化剂在不同硫化气氛进行硫化处理,置于扩散式催化燃烧取暖器。考察硫化气氛、热负荷和耐久试验时间对燃烧取暖器的烟气浓度、起燃温度和燃烧板面平均温度的影响。使用烟气分析仪和红外热成像仪对取暖器的烟气浓度和板面平均温度进行分析。结果表明,纤维催化剂经10%H₂S-H₂气氛硫化120 min,可以制得初始活性良好、稳定性较好且完全符合燃气取暖器CE标准指标的催化剂。     

甲烷催化燃烧用LaMn/Al_2O_3催化剂研究

为获得具有优良低温活性的甲烷燃烧用催化剂,采用稀土La作为助剂制备了系列Mn基催化剂,借助X射线衍射(XRD)、X射线光电子能谱(XPS)和程序升温还原(TPR)技术对催化剂的结构进行了表征,并评价了其对甲烷燃烧的低温催化性能。结果表明,La助剂的添加显著促进了活性组分MnO2的分散,使其更易于还原,且使Mn4+和晶格氧富集于催化剂表面,因而显著提高了催化剂对甲烷催化燃烧的低温活性。当La质量分数为5%时,催化活性最高,甲烷50%转化率对应的温度较未加助剂时降低了70℃,且完全转化的温度低至480℃。     

The oxidative dehydrogenation of ethane over molybdenum-vanadium-niobium oxide catalysts: the role of catalyst composition

The oxidative dehydrogenation of ethane has been studied at atmospheric pressure using molybdenum-vanadium-niobium oxide catalysts in the temperature range of 350–450 °C. The presence of all three oxides together is necessary in order to have active and selective catalysts. The best results have been obtained using a mixture having a Mo V Nb ratio of 19 5 1. Our studies of the variation of oxide composition suggest that the active phase is based on molybdenum and vanadium. Niobium enhances the intrinsic activity of the molybdenum-vanadium combination and improves the selectivity by inhibiting the total oxidation of ethane to carbon dioxide. The apparent activation energies for the conversion of ethane to ethylene, carbon monoxide and carbon dioxide were 18, 27 and 17 kcal/mol, respectively. The addition of water vapor to the gas stream does not affect the product distribution on this catalyst.     

甲烷催化裂解制氢和碳纳米材料研究进展

甲烷通过催化裂解反应可生成不含碳氧化合物（CO_x）的高纯氢和碳纳米材料（如碳纤维或碳纳米管等）,对我国能源结构的调整及新材料的应用具有重要意义。与其他制氢工艺相比,甲烷催化裂解制氢工艺具有反应过程简单、产物清洁无污染、反应成本低等优点,因此该工艺具有重要的工业应用前景。本文重点阐述了催化剂（活性组分、催化剂载体、制备方法等）以及反应条件（催化剂还原条件、空速、反应温度等）对甲烷转化率、氢气产率和碳纳米材料（形貌和产量）的影响并对甲烷催化裂解反应机理、催化剂的失活与再生进行了概述。甲烷催化裂解反应目前仍处于实验室研究阶段,高效催化剂的研制以及流化床反应器的优化是该反应实现工业化应用的必要前提。     

乏风瓦斯流向变换催化燃烧试验研究

为实现低浓度瓦斯气体的高转化率,满足实际工程低温排气的要求,设计制作一套新型流向变换蓄热催化燃烧反应器,并利用模拟气体进行催化燃烧实验研究。结果表明,气体流量为70 L·min^-1、燃烧反应温度控制在500 ℃和甲烷体积分数为0.2%时,甲烷催化燃烧转化率超过80%,出口气体温度低于60 ℃。该系统能满足工程低温排气要求。     

CH4CO2催化重整制合成气的研究进展

综述了CH₄CO₂催化重整制合成气的研究进展，分析讨论了催化剂的研究状况、反应机理、动力学、催化剂失活特性和非常规供能方式在催化重整反应中的应用等。结果表明，CO₂催化重整过程开发成功的关键是有效抑制催化剂积炭失活。     

微型燃烧器内甲烷预混催化燃烧的数值研究

微尺度燃烧存在热量损失大、易熄火、燃烧不完全、转化效率不高等问题,因此对微型燃烧器内甲烷的燃烧采取预混催化燃烧方式来提高燃烧的稳定性和转化效率,为微型发动机碳氢燃料燃烧技术奠定基础。采用连续介质层流有限速率模型和二阶离散方法对微型燃烧器微流道内的催化燃烧、流动和传热进行了三维数值模拟。结果表明,甲烷质量流量和过量空气系数对催化转化效率有一定影响,壁面温度是影响催化转化效率的主要因素。甲烷质量流量、壁面温度与最佳过量空气系数之间具有一定的变化关系。可根据催化温度选择富燃料或富氧燃烧方式来提高微尺度催化转化效率。恒壁温边界条件下,催化燃烧主要发生在燃烧腔的下壁面。     

整装式铝泡沫负载Pd催化剂Pd/AlOOH/Al-foam及其催化甲烷燃烧性能

以三维网络结构的铝泡沫板作为骨架基体和铝源,利用水热氧化法制备整装式拟薄水铝石(Al OOH/Al-foam)纳米阵列,随后通过丙酮辅助-初湿浸渍法,制备出整装式铝泡沫负载Pd催化剂Pd/Al OOH/Al-foam,用于低浓度甲烷催化燃烧反应。在制备条件优化过程中,发现催化剂性能受到纳米阵列的形貌特征、物相组成以及焙烧温度等因素的影响。其中,表面富含羟基的拟薄水铝石可促进Pd颗粒的均匀分散,也增强载体和Pd之间的相互作用,进而提高甲烷燃烧的低温活性。稳定性测试初期活性下降较快,主要原因是表层Al_2O_3纳米阵列载体和Pd纳米颗粒自身的不稳定性导致的Pd颗粒烧结。     

Mn、Fe取代六铝酸盐的结构和甲烷催化燃烧性能

采用化学可控共沉淀法制备了系列取代六铝酸盐LaMe_xAl_12-xO_19-δ（Me＝Fe、Mn）催化剂,研究了焙烧温度和Fe、Mn的离子取代量对催化剂比表面、结构及甲烷催化燃烧活性的影响.结果表明,催化剂前驱物经1000℃焙烧,催化剂中开始有六铝酸盐晶相生成; 当焙烧温度提高到1200℃时,样品主要以六铝酸盐晶相存在.增加Fe、Mn离子取代量可以提高六铝酸盐晶相的结晶度,但同时导致晶粒增大,引起比表面下降.由XPS和TPR分析表明,Mn在六铝酸盐结构中以+2价和+3价混合价态存在,而Fe以+3价形式存在.用Fe和Mn离子取代晶格中的Al³⁺大大提高了六铝酸盐对甲烷催化燃烧活性,当Mn离子的取代数为1,Fe离子的取代数为2时催化剂的活性最高.     

新型催化材料Sr2FeMoO6的葡萄糖溶胶-凝胶法合成及甲烷催化燃烧性能

采用葡萄糖溶胶-凝胶法合成了Sr₂FeMoO₆催化剂,研究了空气、氩气和H₂/N₂ 3种焙烧气氛对产物的结构和性能的影响。运用X射线衍射（XRD）、程序升温还原（TPR）、傅里叶变换红外光谱（FT-IR）、比表面（BET）及磁性测量与甲烷催化燃烧活性评价等技术对所制备的样品进行了表征。XRD实验结果表明,H2/N2气氛下焙烧得到的样品是单相的双层钙钛矿结构氧化物Sr₂FeMoO₆,在氩气下焙烧的样品形成了主相为双层钙钛矿结构氧化物Sr₂FeMoO₆,同时伴有少量的SrMoO₄相,但在空气下焙烧的样品中除了Sr₂FeMoO₆的衍射峰,还出现了强度很高的SrMoO₄相的衍射峰。从TPR、FT-IR和磁性表征结果发现,不同的焙烧气氛所形成的样品程序升温还原图谱和红外光谱均有所差别,H₂/N₂气氛下合成的样品有较好的磁性,而氩气和空气下合成的样品的磁性几乎为零。对于H₂/N₂气氛下合成的单相Sr₂FeMoO₆样品的甲烷催化燃烧活性测试表明,甲烷燃烧起燃温度T₁₀为475℃,完全转换温度T₁₀₀为744℃,可见单相双层钙钛矿型结构化合物Sr₂FeMoO₆对甲烷催化燃烧也有很好的活性。     

甲烷二氧化碳重整镍基催化剂的研究

采用浸渍法制备不同组成催化剂Ni-M/γ-Al₂O₃（M=Zr、Co、Mg、Nd）,通过固定床反应装置考察不同助剂、助剂含量和反应温度对催化剂活性的影响,并对催化剂进行X射线衍射表征。结果表明,14Ni-5Mg/γ-Al₂O₃的催化活性较好,随着反应温度的升高,甲烷转化率和CO收率均升高,反应温度升至800 ℃时,甲烷转化率达97.54%。采用共沉淀法制备载体、浸渍法制备的催化剂14Ni/MgO-Al₂O₃,在反应温度800 ℃、压力1.013 kPa、n(CO₂)∶n(CH₄)=1.2和催化剂用量0.5 g条件下,CO收率高于14Ni-5Mg/γ-Al₂O₃催化剂,但甲烷转化率略低。     

双金属Ni-Co/HZSM-5催化剂上甲烷二氧化碳重整反应

采用等体积浸渍法制备一系列双金属Ni-Co/HZSM-5催化剂,考察反应温度和Ni与Co质量比对甲烷二氧化碳催化重整性能的影响。采用BET和H2-TPR表征催化剂的孔结构和还原性能,结果表明,负载的活性组分均匀分散在HZSM-5载体孔道内。Ni与Co之间存在协同作用,促进了Ni-Co/HZSM-5催化剂的还原性能。单金属Co催化剂几乎对甲烷没有转化活性,双金属Ni-Co催化剂催化活性明显提高,Ni与Co质量比6∶4时,催化剂甲烷二氧化碳重整反应的催化活性和稳定性优于单金属Ni催化剂。     

Calcium oxide and potassium hydroxide catalysed low temperature methane production from graphite and water Comparison of catalytic mechanisms

An experimental study was carried out to obtain information on the catalytic mechanisms involved in the methanation of graphite using, separately, potassium and calcium as catalysts, and water and/or hydrogen as reactants. The mechanisms for the potassium-catalysed graphite—water reaction appear to be the same in the wide temperature range from 473 to 873 K as indicated by the constant activation energy, 46 kJ mol^?1, found for methane production. The intercalation of potassium into the graphite as a possible step in the methane synthesis has been investigated and ruled out. XPS studies indicate the formation of an active form of more positively charged carbon from graphite when graphite is heated at low temperature in the presence of a calcium catalyst and water vapour. The activation energy for this carbon depolymerization reaction is 68.1 kJ mol^?1. Methane formation occurs only in the presence of hydrogen due to its reaction with the active carbon with an activation energy of 106.6 kJ mol^?1.     

甲烷催化还原N2O杂原子磷酸铝分子筛的制备、修饰及其催化性能

采用水热法合成了杂原子质量分数均为1.8%的FeAlPO-5和CuAlPO-5分子筛,比较了两者对甲烷催化还原氧化亚氮的催化性能,结果表明,FeAlPO-5分子筛的催化性能优于CuAlPO-5分子筛。通过添加少量贵金属(Ag和Pd)可进一步提高FeAlPO-5分子筛的低温活性,其中,Pd/FeAlPO-5分子筛的低温活性优于Ag/FeAlPO-5分子筛。