Hydrogen production from coke oven gas over LiNi/γ-Al2O3 catalyst modified by rare earth metal oxide in a membrane reactor

The performance of LiNi/r-Al2O3 catalysts modified by rare earth metal oxide (La2O3 or CeO2) packed on BCFNO membrane reactor was discussed for the partial oxidation of methane (POM) in coke oven gas (COG) at 875 ◦C. The NiO/r-Al2O3 catalysts with different amounts of La2O3 and CeO2 were prepared with the same preparation method and under the same condition in order to compare the reaction performance (oxygen permeation, CH4 conversion, H2 and CO selectivity) on the membrane reactor. The results show that the oxygen permeation flux increased significantly with LiNiREOx/r-Al2O3 (RE = La or Ce) catalysts by adding the element of rare earth especially the Ce during the POM in COG. Such as, the Li15wt%CeO29wt%NiO/ -Al2O3 catalyst with an oxygen permeation flux of 24.71 ml·cm−2·min−1 and a high CH4 conversion was obtained in 875 ◦C. The resulted high oxygen permeation flux may be due to the added Ce that inhibited the strong interaction between Ni and Al2O3 to form the NiAl2O4 phase. In addition, the introduction of Ce leads up to an important property of storing and releasing oxygen.     

生物质气化重整合成二甲醚

以松木粉为原料，采用空气 水蒸气气化制备了富氢气化气，通过添加甲烷重整富氢气化气，调整了合成气化学当量比，在260 ℃、4 MPa、12 000 h－1条件下，对生物质合成气一步法合成二甲醚进行了实验研究。结果表明：引入甲烷重整，活化了富氢气化气中过量的CO2，甲烷的最佳加入量为CH4/CO2=1，生物质碳转化率达到70%以上，尾气中二甲醚选择性达到69.6%。     

反应条件对Ni-CaO-ZrO2催化剂上CH4-CO2重整反应及积炭的影响

用共沉淀法制备了Ni-CaO-ZrO₂催化剂,并将其用于CH₄-CO₂重整反应。考察了反应温度、空速和反应物配比对催化剂性能和积炭的影响。通过热力学计算和实验表征研究发现,反应条件对CH₄-CO₂重整反应结果和积炭有重要的影响。由于高温条件同时有利于CH₄裂解和碳物种的及时消除,升高温度可以提高催化剂的活性和稳定性。增大空速则使CH₄的转化率和消碳反应的速率均降低,导致积炭量增加。同时,反应物配比对催化剂表面的积炭量也有很大影响;稍高的CO₂/CH₄摩尔比有利于抑制CH₄-CO₂重整反应过程中的积炭。     

制备方法对Ni/MgO/Al2O3催化剂在甲烷与二氧化碳重整反应活性的影响

采用浸渍－还原法制备的Ｎｉ／ＭｇＯ／Ａｌ２Ｏ３在ＣＨ４与ＣＯ２重整制合成气反应中显示出良好的催化性能和一定的抗积炭能力;在１０２３Ｋ下流动反应气氛中连续运转１００ｈ,未见活性下降,ＣＨ４及Ｃ弦均为９０％左右,ＣＯ收率高于９０％,实验还发现,ＣＨ４转化率随着原料气中ＣＯ２浓度的增加而升高,当Ｖ（ＣＯ２）／Ｖ（ＣＨ４）＝２时ＣＨ４转化率可达１００％,通过ＢＥＴ比表面积测定及ＸＲＤ,ＴＥＭ等分析手段,比     

透氧膜反应器内NiO/MgO催化焦炉煤气重整反应途径

对透氧膜反应器内焦炉煤气(COG)重整反应模型进行分析.通过H2+N2、CH4+N2、CO+N2和H2+CH4+N2混合气在透氧膜反应器内重整反应,以及有无催化剂下重整反应和催化剂床层厚度重整反应实验,推测焦炉煤气重整反应模型:首先焦炉煤气中H2在催化剂活性金属镍颗粒上吸附解离,解离后的氢向高活性位迁移"(三相界面")并与膜表面侧晶格氧(或O2-)反应生成H2O.同时CH4也可能在活性镍颗粒上裂解生成CH3*和H*,反应生成的H2O与膜表面催化剂上裂解的碳反应生成H2和CO.未反应完的H2O在催化剂床层内与剩余CH4反应生成H2和CO.     

Performance of a mixed-conducting ceramic membrane reactor with high oxygen permeability for methane conversion

A mixed-conducting perovskite-type Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCFO) ceramic membrane reactor with high oxygen permeability was applied for the activation of methane. The membrane reactor has intrinsic catalytic activities for methane conversion to ethane and ethylene. C₂ selectivity up to 40–70% was achieved, albeit that conversion rate were low, typically 0.5–3.5% at 800–900°C with a 50% helium diluted methane inlet stream at a flow rate of 34 ml/min. Large amount of unreacted molecular oxygen was detected in the eluted gas and the oxygen permeation flux improved only slightly compared with that under non-reactive air/He experiments. The partial oxidation of methane to syngas in a BSCFO membrane reactor was also performed by packing LiLaNiO/γ-Al₂O₃ with 10% Ni loading as the catalyst. At the initial stage, oxygen permeation flux, methane conversion and CO selectivity were closely related with the state of the catalyst. Less than 21 h was needed for the oxygen permeation flux to reach its steady state. 98.5% CH₄ conversion, 93.0% CO selectivity and 10.45 ml/cm² min oxygen permeation flux were achieved under steady state at 850°C. Methane conversion and oxygen permeation flux increased with increasing temperature. No fracture of the membrane reactor was observed during syngas production. However, H₂-TPR investigation demonstrated that the BSCFO was unstable under reducing atmosphere, yet the material was found to have excellent phase reversibility. A membrane reactor made from BSCFO was successfully operated for the POM reaction at 875°C for more than 500 h without failure, with a stable oxygen permeation flux of about 11.5 ml/cm² min.     

Cofeeding of Methane and Ethane to Produce Syngas over a LiLaNiO/γ-Al_2O_3 Catalyst

There are abundant supplies of mixture gases containing CH, and C,H, from natural gas,FCC (Fluidized Catalytic Cracking) dry gas, refinery gas, elc. Commonly, the amount ofC,H, is relatively lower than that of CH,. With regard to the utilization of methane,partial oxidation of methane to syngas over nickel based catalysts has received intensiveallention l'2. For mixture gases containing CH# and C,H,, their conversion to syngas isalso of significance (but has not gained adequate attentio…     

水蒸气对Ni/Ce-Zr-Al-Ox催化剂上CO2重整CH4瓜的影响

采用水热合成-负载法制备了Ni/Ce-Zr-Al-Ox催化剂,测试了该催化剂上CO2重整CH4反应的活性和稳定性,并考察了添加少量水蒸气对CO2重整CH4反应的影响.结果表明,在不含水蒸气的反应气中反应198 h后CH4和CO2的转化率分别为89%和98%,H2/CO摩尔比约为1.00,且没有任何失活.添加3.2%的水蒸气后,CH4转化率提高到94%,CO2转化率不变,H2/CO摩尔比约提高0.06,同时稳定性也很好.计算结果表明,添加少量水蒸气后,CO2重整CH4被促进,逆水煤气反应被抑制,而水蒸气重整CH4没有明显变化.     

Methane oxidation at redox stable fuel cell electrode La0.75Sr0.25Cr0.5Mn0.5O(3-delta)

Because of its widespread availability, natural gas is the most important fuel for early application of stationary fuel cells, and furthermore, methane containing biogases are one of the most promising renewable energy alternatives; thus, it is very important to be able to efficiently utilize methane in fuel cells. Typically, external steam reforming is applied to allow methane utilization in high temperature fuel cells; however, direct oxidation will provide a much better solution. Recently, we reported good electrochemical performance for an oxide anode La0.75Sr0.25Cr0.5Mn0.5O3 (LSCM) in low moisture (3% H2O) H2 and CH4 fuels without significant coking in CH4. Here, we investigate the catalytic activity of this oxide with respect to its ability to utilize methane. This oxide is found to exhibit fairly low reforming activity for both H2O and CO2 reforming but is active for methane oxidation. LSCM is found to be a full oxidation catalyst rather than a partial oxidation catalyst as CO2 production dominates CO production even in CH4-rich CH4/O2 mixtures. X-ray adsorption spectroscopy was utilized to confirm that Mn was the redox active species, clearly demonstrating that this material has the oxidation catalytic behavior that might be expected from a Mn perovskite and that the Cr ion is only present to ensure stability under fuel atmospheres.     

CH4-CO2 reforming to syngas over Pt-CeO2-ZrO2/MgO catalysts: Modification of support using ion exchange resin method

Pt-CeO2-ZrO2/MgO (Pt-CZ/MgO) catalysts with 0.8 wt% Pt, 3.0 wt% CeO2 and 3.0 wt% ZrO2 were prepared by wet impregnation method. Support MgO was obtained using ion exchange resin method or using commercial MgO. XRD, BET, SEM, TEM, DTA-TG and CO2-TPD were used to characterize the catalysts. CH4-CO2 reforming to synthesis gas (syngas) was performed to test the catalytic behavior of the catalysts. The catalyst Pt-CZ/MgO-IE(D) prepared using ion exchange resin exhibits more regular structure, smaller and more unique particle sizes, and stronger basicity than the catalyst Pt-CZ/MgO prepared from commercial MgO. At 1073 K and atmospheric pressure, Pt-CZ/MgO-IE(D) catalyst has a higher activity and greater stability than Pt-CZ/MgO catalyst for CH4-CO2 reforming reaction at high gas hourly space velocity of 36000 mL/(g·h) with a stoichiometric feed of CH4 and CO2. Activity measurement and characterization results demonstrate that modification of the support using ion exchange resin method can promote the surface structural property and stability, therefore enhancing the activity and stability for CH4-CO2 reforming reaction.     

High coke-resistance of K-Ca-promoted Ni/a-Al2O3 catalyst for ch4 reforming with CO2

Summary  K-Ca-promoted Ni/&agr;-Al2O3 catalyst exhibited higher activity better coke-resistance than Ni/&agr;-Al2O3 for CH4 reforming with CO2 under different reaction conditions. Temperature-programmed activation process of CH4 reforming with CO2 was investigated on these catalysts.     

Ni/ZrO2催化剂上甲烷水蒸气重整反应的研究

研究了Ni/ZrO2催化剂对甲烷水蒸气重整制合成气的反应性能。考察了催化剂的还原温度、载体焙烧温度以及反应温度、原料配比和空速等对催化剂性能的影响。利用XRD、TEM、XPS等手段对催化剂的织构形貌进行了表征。研究表明，Ni/ZrO2催化剂用于甲烷水蒸气重整制合成气不仅具有较高的活性，也具有较好的稳定性。水蒸气比增加，CH4转化率增大、CO选择性下降。CH4转化率及CO选择性均随空速增大而下降。使用10%Ni/ZrO2催化剂，在650 ℃、空速1.984×104 h－1、原料气配比H2O∶CH4∶N2=2∶1∶2.67的条件下，获得CH4转化率85%、CO选择性70%的结果。     

焙烧温度对有色金属尾矿载体及Ni基催化剂的性能影响

以尾矿为载体原料,经不同温度焙烧预处理、等体积浸渍制备了一系列负载型Ni/SiO2-CaO-Fe2O3催化剂并用于CO2重整CH4制合成气,重点考察了载体原料的焙烧温度对催化剂性能的影响.用ICP-AES,XRD测定了有色金属尾矿的成分,用H2-TPR,CO2-TPD,TPO等对催化剂的还原性能、吸附性能、抗积炭性能进行了表征.结果表明,载体原料经850℃焙烧后所负载的镍催化剂在800℃条件下CO2转化率为78.5%,CH4转化率为71.2%,CO和H2选择性分别达到92.2%,89.5%.     

混合导体透氧膜反应器中甲烷部分氧化反应的催化行为(英文)

应用组成为Ba0.5Sr0.5Co0.8Fe0.2O3-(的钙钛矿型混合导体陶瓷膜制成膜反应器。该膜在进行氧分离的同时具有活化甲烷氧化偶联的催化功能。随着温度升高和膜的富氧端氧分压的增大,透氧量有所增加。在空气、氦气的氧分压梯度下,850(C,膜厚度为1.5 mm时,JO2可达到1.2 mL/(cm3(min)。同时在800(C~900(C温度范围内,该膜对于甲烷转化为乙烷和乙烯一般只具有0.5%~3.5%的低转化率,而选择性可达40%~70%。在反应尾气中发现了大量的未反应的分子氧,说明过量的氧与甲烷未经催化反应的气相反应导致了C2的选择性相对较低。OCM膜反应模式情况下的透氧量与空气、氦气梯度情况下的透氧量相比只有微小增加,这与POM膜反应模式情况下透氧量大量增加显著不同。     

化学循环重整甲烷制合成气LaBO3钙钛矿型氧载体研究

采用溶胶-凝胶法制备了不同B位可变价离子的La-B-O复合氧载体(B=Cr、Ni),采用XRD、BET、FT-IR、H2-TPR及CH4-TPSR等进行了表征,并用于化学循环重整(CLR)CH4反应中.结果表明,LaNiO3氧化物更易于与CH4发生深度氧化和选择氧化,LaCrO3氧化物则利于CH4裂解,其氧物种氧化CH4的能力较弱.在连续流动CLR反应中,LaNiO3具有较高的供氧量和持续供氧能力,能将CH4选择氧化为H2/CO=1.45的合成气,其CH4转化率和CO选择性分别达到23.4%和86.9%,且其结构保持了较高的稳定性.     

Weakly coordinating anions HA2-generated from oxoanions A- and their conjugate acids. Coordination equilibria,ionic conductivities,and the structures of [Cu2(H(CH3SO3)2)4]n and [Cu(CO)(H(CF3CO2)2)]2

The coordination or ion pairing of the hydrogen-bonded anions H(CF3CO2)2- and H(CH3SO3)2- to NEt4+, Li+, Cu+, and/or Cu2+ was investigated. The structure of [Cu2(H(CH3SO3)2)4]n consists of centrosymmetric dimeric moieties that contain two homoconjugated (CH3SO2O-H...OSO2CH3)- anions per Cu2+ ion, forming typical Jahn-Teller tetragonally elongated CuO6 coordination spheres. The oxygen atoms involved in the nearly linear O-H...O hydrogen bonds (O...O approximately 2.62 A) are not coordinated to the Cu2+ ions. The structure of Cu2(CO)2(H(CF3-CO2)2)2 consists of pseudo-C2-symmetric dimers that contain one homoconjugated (CF3COO-H...OCOCF3)- anion per Cu+ ion, forming highly distorted tetrahedral Cu(CO)O3 coordination spheres. Three of the four oxygen atoms in each hydrogen-bonded H(CF3CO2)2- anion are coordinated to the Cu+ ions, including one of the oxygen atoms in each O-H...O hydrogen bond (O...O approximately 2.62 A). Infrared spectra (v(CO) values) of Cu(CO)(CF3CO2) or Cu(CO)(CH3SO3) dissolved in acetonitrile or benzene, with and without added CF3COOH or CH3SO3H, respectively, demonstrate that HA2- anions involving carboxylates or sulfonates are more weakly coordinating than the parent anions RCO2- and RSO3-. Direct current conductivities of THF solutions of Li(CF3CO2) containing varying concentrations of added CF3COOH further demonstrate that Li+ and NEt4+ ion pair much more weakly with H(CF3CO2)2- than with CF3CO2-.     

有氧气氛下等离子体甲烷偶联反应的研究

近年来,非平衡等离子体应用于甲烷直接转化的研究备受关注,但多数研究工作采用的是低气压下微波或高频放电产生的非平衡等离子体[1－9].在常压下获得非平衡等离子体一般是通过脉冲电晕放电或介质阻挡放电产生的[10,11].Liu等[12]采用电晕放电（非脉冲）研究了CH4＋O2＋He(pCH4=2.03×104Pa,pO2=5.07×103Pa,He平衡)体系的甲烷偶联反应.　　如前文[13]所述,脉冲电晕等离子体是一种新型常压非平衡等离子体,其电子通过上升沿陡峭的窄脉冲电场加速而获得能量（1～20eV）.将其应用于甲烷偶联反应,不仅具有反应条件温和（常温常压）…     

IR STUDIES ON MECHANISM OF DIRECT OXIDATION OF METHANE TO SYNTHESIS GAS OVER A Ni/Al2O3 CATALYS

The mechanism of the CH4/O2 to syngas reaction has been investigated by FT-IR over a 2.9%(wt)Ni/Al2O3. IR spectra of adsorption of CH4 indicate that chemisorbed O atoms can react selectively with active carbon species (arising from CH4 decomposition) to give CO. IR spectra of adsorption of CH4/O2(2:1 mole ratio) mixture show that CO2 and H2O are the detectable products with no CO, revealing that the reforming of remaining CH4 would not take place. We propose that CO and H2 are primary products in this reaction.     

Ni/Al_2O_3催化剂上CH_4部分氧化制合成气机理的IR研究(英文)

在２．９％（ｗｔ）Ｎｉ／Ａｌ２Ｏ３催化剂上用ｉｎｓｉｔｕＦＴＩＲ研究了ＣＨ４部分氧化制合成气的反应机理。结果表明，催化剂表面的活性碳物种与化学吸附的Ｏ原子反应生成ＣＯ；ＣＨ４／Ｏ２（２：ｌ）混合气在催化剂表面吸附的ＩＲ谱图表明只有Ｈ２Ｏ和ＣＯ２存在，说明ＣＨ４和ＣＯ２的重整反应没有发生。因此，我们认为ＣＯ和Ｈ２是一级产物。     

焦炉煤气甲烷重整制氢热力学分析和实验研究(英文)

对焦炉煤气甲烷部分氧化重整热力学进行分析,考察反应温度、CH4/O2摩尔比及水蒸气加入量等因素对重整性能的影响,并分析焦炉煤气原始氢含量对其部分氧化重整性能的影响.分析结果表明甲烷转化率均随CH4/O2摩尔比和水蒸气加入量的增大以及反应温度的升高而增大.在CH4/O2摩尔比1.7-2.1,温度825-900℃及压力1.01×105Pa的反应条件下,可得较好重整性能;甲烷转化率,氢及一氧化碳的选择性分别为91.0%-99.9%,87.0%-93.4%和100%-107%,重整后得到的氢量增大到原始氢量的1.95-2.05倍,每摩尔焦炉煤气消耗的热量仅为2.94J,同时得出在CH4/O2摩尔比2,温度825-900℃及1.01×105Pa条件下,往焦炉煤气内添加体积分数为2%-4%的水蒸气时重整性能得到较大提高;重整后甲烷转化率、氢及一氧化碳选择性分别由92.6%、87.2%、104%增大到98.6%、96.4%、107%.并在BaCo0.7Fe0.2Nb0.1O3-δ透氧膜反应器上研究NiO/MgO固溶体催化剂焦炉煤气部分氧化重整性能.结果表明该重整反应效果较好,于875℃下获得16.3mL.cm-2.min-1透氧量,95%甲烷转化率及80.5%氢和106%一氧化碳选择性.且所得实验结果与热力学分析结果符合较好,表明NiO/MgO固溶体催化剂有较好的催化重整性能.