Influence of support on resistance to carbon-deposition of catalyst for CH4, CO2 with O2 to synthesis gas

In the reaction of catalytic oxidation of CH₄, CO₂ with O₂ to synthesis gas, carbon-deposition is an important factor for deactivation. By adding different oxides to Ni/Al₂O₃ catalyst, its resistance to carbon-deposition was improved. The experimental results indicate that the order of resistance to carbon-deposition is as follows: Ni/CaO-Al₂O₃>Ni/MgO-Al₂O₃>Ni/ TiO₂-Al₂O₃ > Ni/CeO₂-Al₂O₃>Ni/La₂O₃-Al₂O₃>Ni/Y₂O₃-Al₂O₃>Ni/Fe₂O₃-Al₂O₃>Ni/Al₂O₃. The catalysts were characterized by CO₂-TPD, O₂-TPD and XPS methods. Here the relation between the order of resistance to carbon-deposition and performance of catalyst is discussed.     

助剂对CH4,CO2和O2制合成气反应催化剂性能的影响

考察了NiCaO-Al2O3催化剂中添加碱金属、碱土金属、稀土金属氧化物、CuO助剂及CaO含量对催化剂性能的影响。结果表明,10Ni-2K-2Cu15CaO-Al2O3催化剂对CH4、CO2和O2制合成气反应具有较高的催化活性、选择性和较好的抗积炭性能。通过TPR、CO-TPD、XPS和XRD对催化剂进行表征,发现K2O、CuO和CaO的添加削弱了活性组分Ni与载体Al2O3间的相互作用,增加Ni的电子密度,加速了CO与H2的脱附,从而抑制了CH4深度裂解积炭和CO歧化积炭。此外,这些助剂的添加也提高了Ni的分散度,增强了催化剂的抗积炭能力。     

Influence of the Sol-Gel Method on a NiO/Al2O3 Catalyst for CH4/O2 to Syngas Reaction

NiO/-Al₂O₃ catalysts were prepared by the impregnation and the sol-gel method. The sintering and loss of nickel, carbon deposition and 80 h life-test for POM reaction over the catalyst were investigated by a flow-reactor and by XPS, TG, EXAFS and AAS analysis. The results indicated that the sol-gel method could enhance the ability to suppress carbon deposition and to resist nickel sintering and loss over nickel-based catalysts.     

Effect of CeO_2 Promoter on the Performance of Catalyst for CH_4, CO_2with O_2 to Synthesis Gas

Inrecentyears,thereactionofmethane,carbondioxidewithoxygentosynthesisgashasbeenreceivingmore.attentionfromthevieWPointofPrpservingglobalenvironment,becauseCH#andCO,areofgreenhousegasesandtheircontributiontoglobalwarmingisverylargeowingtotheirhugeamountreleasedintheatmosphere'.Inaddition,therearetwoadvantagesinthisprocessobviously,bychangingtheratiooffeed,itcanachievethermalneutralizingandtheCO/H,ratiocanlbebovariedintherangeof0.5~ltofitdifferentindustrialrequirement.Therearehardlyanypapers…     

Direct Synthesis of Acetic Acid from CH4 and CO2 in the Presence of O2 over a V2O5-PdCl2／Al2O3 Catalyst

The possibility of synthesizing acetic acid from CH4 and CO2 in the presence of O2 over a V2O5-PdCl2/Al2O3 catalyst has been explored. The result shows that it is feasible in catalyzing a direct conversion of CH4, CO2 and O2 to acetic acid. It is concluded that both CO2 and O2 are involved in the formation of acetic acid.     

Effect of La2O3／γ—Al2O3 Catalyst on the Activation of CH4 and CO2 to C2 Hydrocarbons under Non—equilibrium Plasma

In the reaction of methane and carbon dioxide to C2 hydrocabons under non-equilibrium plasma, methane conversion was decreased,but selectivity of C2 hydroxarbons was increased when using La2O3/γ-Al2O3 as catalyst. So the yield of C2 hydrocarbons was higher than using plasma alone. The synergism of La2O3/γ-Al2O3 and plasma gave methane conversion of 24.9% and C2 yield of 18.1%. The distribution of C2 hydrocarbons changed when Pd-La2O3/γ-Al2O3 was used as catalyst,the major C2 product was ethylene.     

CO_2 Reforming of CH_4 over Ni/CeO_2-ZrO_2-Al_2O_3 Prepared by Hydrothermal Synthesis Method

The Ni/CeO2-ZrO2-Al2O3 catalyst with different Al2O3 and NiO contents were prepared by hydrothermal synthesis method. The catalytic performance for CO2 reforming of CH4 reaction, the interaction among components and the relation between Ni content and catalyst surface basicity were investigated. Results show that the interaction between NiO and Al2O3 is stronger than that between NiO and CeO2-ZrO2.The addition of Al2O3 can prevent the formation of large metallic Ni ensembles, increase the dispersion of Ni, and improve catalytic activity, but excess Al2O3 causes the catalyst to deactivate easily. The interaction between NiO and CeO2 results in more facile reduction of surface CeO2. The existence of a small amount of metallic Ni can increase the number of basic sites. As metallic Ni may preferentially reside on the strong basic sites, increasing Ni content can weaken the catalyst basicity.     

CO2 Reforming of CH4 over Ni／CeO2-ZrO2-Al203 Prepared by Hydrothermal Synthesis Method

The Ni/CeO2-ZrO2-A12O3 catalyst with different A12O3 and NiO contents were prepared by hydrothermal synthesis method. The catalytic performance for CO2 reforming of CH4 reaction, the interaction among components and the relation between Ni content and catalyst surface basicity were investigated. Results show that the interaction between NiO and A12O3 is stronger than that between NiO and CeO2-ZrO2. The addition of A12O3 can prevent the formation of large metallic Ni ensembles, increase the dispersion of Ni, and improve catalytic activity, but excess A12O3 causes the catalyst to deactivate easily. The interaction between NiO and CeO2 results in more facile reduction of surface CeO2. The existence of a small amount of metallic Ni can increase the number of basic sites. As metallic Ni may preferentially reside on the strong basic sites, increasing Ni content can weaken the catalyst basicity.     

CoII Cryptates Convert CO2 into CO and CH4 under Visible Light

Three Co^II octaazacryptates, with different substituents on the aromatic rings (Br, NO₂, CCH), were synthesised and characterised. These and the already published non-substituted cryptate catalysed CO₂ photoreduction to CO and CH₄ under blue visible light at room temperature. Although CO was observed after short irradiation times and a large range of catalyst concentrations, CH₄ was only observed after longer irradiation periods, such as 30 h, but with a small catalyst concentration (25 nm ). Experiments with ¹³C labelled CO₂ showed that CO is formed and reacts further when the reaction time is long. The CCH catalyst is deactivated faster than the others and the more efficient catalyst for CH₄ production is the one with Br. This reactivity trend was explained by an energy decomposition analysis based on DFT calculations.     

金属-载体相互作用对CH4/CO2重整反应中Rh基催化剂抗积炭性能的影响

考察了Rh/Al2O3,Rh/SiO2和Rh/CeO2催化剂上金属-载体间相互作用对CH4/CO2重整反应抗积炭性能的影响,并与反应前后催化剂的程序升温还原和程序升温氧化(TPO)测试结果相关联.实验发现,Rh与Al2O3和SiO2载体间的相互作用越强,催化剂还原后Rh的分散度越高,晶粒越小,高分散的Rh表面生成的碳物种CHx越多,其作为活泼的反应中间体越易与CO2反应生成CO和H2.而游离态的Rh还原后晶粒较大,生成的碳物种与CO2反应能力较低,从而导致催化剂失活.TPO和CO2脉冲实验结果表明,反应过程中Rh/CeO2催化剂上反应生成的CHx物种比Rh/Al2O3和Rh/SiO2上的CHx物种更活泼.同时由于Rh-CeO2间独特的相互作用,部分CeO2还原后生成CeO2-x和氧空位,促进CO2分子的活化解离,导致生成的表面氧容易与CHx反应,从而抑制催化剂积炭.     

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     

三通道气相色谱法监测大气中CH_(4)、CO、CO_(2)、N_(2)O和SF_(6)北大核心CSCD

我国正处于“碳达峰、碳中和”的关键时期,准确认识我国温室气体浓度时空格局以及变化对于评估“碳达峰”和“碳中和”行动成效非常重要。当前我国近地面温室气体高精度监测主要依赖进口的光学监测主机,单台仪器成本高且监测要素有限。为此,该研究基于传统的气相色谱法,自主设计了一套三通道气相色谱分析系统,在单台仪器上实现了5种主要长寿命温室气体(CH_(4)、CO、CO_(2)、N_(2)O和SF_(6))的高精度监测。对该系统的精密度、线性响应情况和准确度进行的针对性测试实验表明系统检测性能满足世界气象组织/全球大气观测(WMO/GAW)质控标准。针对环境浓度的CH_(4)、CO、CO_(2)、N_(2)O和SF_(6)的连续分析精密度分别达0.08%、1.90%、0.05%、0.08%、0.66%。准确度测试中,5种气体(CH_(4)、CO、CO_(2)、N_(2)O和SF_(6))使用回归方程计算所得值与标称摩尔分数间的偏差分别达0.15×10-9、0.20×10-9、0.37×10-6、0.35×10-9、0.02×10-12(摩尔分数),CH_(4)、CO、CO_(2)、N_(2)O和SF_(6)仪器响应值与标称摩尔分数的线性拟合相关系数(R2)均为0.9999,线性拟合残差和准确度基本达到WMO/GAW拓展质控目标。该系统对杭州城区大气温室气体在线连续监测结果显示,2021年5~7月期间大气CH_(4)、CO、CO_(2)和N_(2)O呈明显的日变化特征,主要受人为活动影响。综合测试和试运行结果表明,该研发系统具备良好的精密度、准确度、线性和稳定性,与目前国内广泛进口的仪器相比,具有技术自主可控、运行成本更低、自动化水平更高等优势,能满足多种温室气体在线监测研究的需求。     

无模板剂一锅法合成介孔Ni-CaO-ZrO2 催化剂及其在CH4-CO2重整反应中的应用研究

通过无模板剂一锅法制备出一种具有较大比表面积和孔容的介孔Ni-CaO-ZrO₂催化剂,并将其用于CH₄-CO₂重整反应过程。利用N₂吸附-脱附(BET)、SEM、TEM、X射线粉末衍射(XRD)、程序升温还原(H₂-TPR)以及热重(TG)等手段对催化剂进行了表征。结果表明,该催化剂具有较强的金属-载体相互作用,这种强金属-载体相互作用(SMSI)使Ni与载体紧密接触,有利于吸附物种在界面进行快速反应,使催化剂在反应过程中具有较高的反应活性和稳定性。虽然反应后的催化剂表面有一定量的积炭生成,但这些积炭多以丝状碳为主,并不会覆盖催化剂的活性位点。     

大气压等离子体射流重整CH_4-CO_2制合成气

采用大气压等离子体射流,以CH4和CO2直接作为放电气体进行常压下重整制合成气的实验研究,考察了等离子体射流的放电特征及放电距离、放电功率、原料气配比和流量对反应的影响。结果表明,该等离子体具有放电稳定、均匀的特征。重整反应的主要产物为合成气,只有少量的H2O和积炭生成。优化的反应条件为放电距离为9 mm,CH4和CO2的摩尔比为4/6。当原料气流量为1 000 mL/min,放电功率为88.4 W时,CH4和CO2的最高转化率为分别为94.99%和87.23%。甲烷和二氧化碳的转化率随放电功率的增加而增加,随流量的增加而减少。     

大气压等离子体射流重整CH4-CO2制合成气

采用大气压等离子体射流,以CH₄和CO^₂直接作为放电气体进行常压下重整制合成气的实验研究,考察了等离子体射流的放电特征及放电距离、放电功率、原料气配比和流量对反应的影响。结果表明,该等离子体具有放电稳定、均匀的特征。重整反应的主要产物为合成气,只有少量的H₂O和积炭生成。优化的反应条件为放电距离为9mm,CH₄和CO₂的摩尔比为4/6。当原料气流量为1000mL/min,放电功率为88.4W时,CH4和CO₂的最高转化率为分别为94.99%和87.23%。甲烷和二氧化碳的转化率随放电功率的增加而增加,随流量的增加而减少。     

Reforming of CH4 with CO2 over Rh/H-Beta:Effect of Rhodium Dispersion on the Catalytic Activity and Coke Resistance

The effect of Rh dispersion on reforming of CH₄ with CO₂ over H‐Beta supported Rh catalysts has been investigated. The CH₄ and CO₂ conversion over the catalysts increase with increasing Rh loading from 0.5 wt% to 4.0 wt% in the reaction temperature range of 823–1123 K. The high TOF of CH₄ over 0.5 wt% and 1.0 wt% Rh/H‐beta may be attributed to high dispersion of rhodium species. The catalysts before and after the reaction were characterized by XRD, TEM, and TG‐DTA and the results indicate the catalysts with Rh loading of 0.5 wt% and 1.0 wt% exhibiting high resistance to coke. Under controllable conditions, we confirm that the coke is originated from methane dissociation and can be substantially oxidized by active oxygen species dissociated from the adsorbed carbon dioxide on the catalyst with high dispersion of Rh species.     

La2NiO4／Al2O3催化剂上CH4／CO2的重整

 通过溶胶－凝胶方法制备了尖晶石结构的La2NiO4／Al2O3催化剂，采用BET，XRD和TG表征了催化剂的孔分布、比表面积、体相组成以及凝胶样品的热失重和热分解过程．将催化剂应用于CH4／CO2重整反应制合成气，考察了惰性气体和反应温度对转化率、选择性以及积碳的影响．结果表明，在高空速（GHSV＝4．8×104ml／（g·h））下，CH4和CO2转化率分别为51％和60％，CO和H2的选择性约为98％和92％，惰性气体He的引入明显地提高了CH4和CO2的转化率．     

BNiAl_2O_3催化剂上用脉冲反应研究CO_2的活化及其与CH_4的反应(英文)

用脉冲微反应系统研究了１０２３Ｋ下，ＣＯ２在Ｎｉ／Ａｌ２Ｏ３上的裂解及其与ＣＨ４的反应，发现ＣＯ２裂解吸附产生Ｏ（ａｄ）和ＣＯ，该反应步骤较慢。产生的ＣＯ会进一步在Ｎｉ表面裂解，而由ＣＨ４裂解产生的活性碳物种与Ｏ（ａｄ）的反应是一较快步骤。     

Ce1-xZrxO2的氧化还原性能及其对CO2重整CH4反应的影响

 通过X射线衍射和程序升温还原技术对Ce1-xZrxO2(0≤x≤1)催化剂的结构和氧化还原性能进行了研究,同时考察了Ce1-xZrxO2催化剂在CO2重整CH4反应中的催化性能,并与其氧化还原性能进行了关联. 结果表明,当x≤0.25时, Ce1-x-ZrxO2以立方相Ce-Zr-O固溶体形式存在,氧化还原性随着Zr含量的增加而增加; 当x＞0.25时,以四方ZrO2相和立方相Ce-Zr-O固溶体的混合相存在,氧化还原性随着Zr含量的增加而减弱. Ce0.75Zr0.25O2具有最高的氧化还原性, Ce1-xZrxO2对CO2重整CH4反应的催化活性依赖于其氧化还原性,催化剂的氧化还原性越强,反应物(CO2和CH4)的转化率越高,催化剂的稳定性也越好. 氧化还原性能最强的Ce0.75Zr0.25O2催化剂表现出最高的催化活性、抗积炭能力和稳定性.