甲烷合成催化剂抗积炭能力研究

在模拟焦炉气合成甲烷反应过程中,利用热重分析（TG）,研究了催化剂在一定反应温度范围内的主要积炭类型,以及在不同工艺条件下的抗积炭能力.研究发现：反应温度500℃以上,催化剂的积炭类型以CH4分解为主.反应温度和CH4浓度对催化剂的抗积炭能力影响较大,温度越高积炭量越大,CH4浓度越高积炭量也越大.     

平板微反应器内甲烷催化部分氧化重整数值分析

联合使用可以计算表面反应的化学反应动力学软件CHEMK IN4.0和计算流体力学软件CFD,对平板微反应器中Rh催化剂涂层上甲烷部分氧化重整制合成气进行了数值分析,并探讨了反应通道高度和长度对反应性能的影响。结果表明:在较短的接触时间内,能够得到较高的甲烷转化率和稳定的合成气组分,氢气与一氧化碳的摩尔比在1.5—2.0;在绝热边界条件下,反应通道高度增大,甲烷的转化率、出口氢摩尔分数以及氢选择性降低,出口温度升高;反应通道长度增大,甲烷的转化率、出口氢摩尔分数以及氢选择性提高,出口温度降低。     

甲烷常压非催化部分氧化制合成气研究

考察了常压下甲烷非催化部分氧化制合成气过程中,甲烷转化率、气体产物产率以及积炭率随反应器温度、进气配比、原料气流量变化的影响。通过考察反应器温度对制备合成气过程的影响结果,分析了甲烷非催化部分氧化制合成气过程的反应机理。     

甲烷无氧芳构化反应器及催化剂积炭的研究进展

综述了甲烷无氧芳构化反应的研究进展,对甲烷无氧芳构化反应机理、反应器的选择、催化剂的选择、催化剂积炭失活与再生等方面做了讨论,对甲烷无氧芳构化的工艺开发、对能源利用、催化科学均具有重大意义。     

国内外甲烷催化部分氧化催化剂研究

主要讨论国内外甲烷催化部分氧化催化剂在载体、助剂、活性组分及制备方法等方面的研究进展,对改善催化剂的抗积炭性、提高催化剂的稳定性和选择性提供了建议及参考。     

渣油加氢处理催化剂积炭分析

采用热重、差热分析、低温氮吸附、元素分析等技术对渣油加氢处理过程中5种催化剂上的积炭进行了分析.结果表明,结焦催化剂表面积炭沉积和孔道堵塞现象严重,比表面积和孔容大量损失,孔分布向小孔范围迁移,催化剂孔径越小,损失越严重.催化剂上沉积的焦炭可分为低温型和高温型两种,前者燃烧放热集中在400℃左右,后者集中在470℃左右.积炭形成类型与积炭前身物--沥青质的结构有关,芳香碳分率低,缩合指数小的沥青质形成低温型积炭;芳香碳分率高,缩合指数大的沥青质形成高温型积炭.催化剂促使沉积物脱氢形成积炭,并且使积炭从低温型向高温型转化,催化剂活性越高,转化越明显.     

甲烷催化部分氧化制合成气催化剂的研究进展

叙述了甲烷催化部分氧化制合成气催化剂的最新研究进展,包括含钴的钙钛矿、碳化钼、碳化、Ｎｉ／α－Ａｌ２Ｏ３,Ｐｔ－Ｎｉ／α－Ａｌ２Ｏ３、ｌａＯ３＿ＮｉＯ／Ａｌ２Ｏ３等。     

煤制天然气甲烷合成催化剂防积炭工艺的优化分析与探讨

新天煤化工甲烷合成装置自原始开车以来,由于甲烷合成催化剂防积炭工艺不完善,长期受到催化剂积炭的不利影响。针对此问题,详细介绍了甲烷合成催化剂积炭的机理和危害,阐述了当前甲烷合成催化剂防积炭工艺方法;通过针对性的系统分析,指出了防积炭工艺存在的问题,并从改造甲烷合成主反应器出口取样器和优化系统补水操作方面提出了相应的改进措施。     

甲烷二氧化碳重整制合成气中积炭效应的数值模拟

通过建立包含动量、质量传递以及化学反应动力学方程的多物理场耦合数值模型,对以Ni为催化剂的甲烷二氧化碳重整制合成气过程中的积炭效应展开了计算。计算结果阐明了包含多孔介质催化剂段的反应通道中的速度场及压力分布,以及在通道中随气体流动以及沉积在催化剂表面的碳颗粒的浓度分布,分析了积炭对 催化剂孔隙率和渗透率的影响,并进一步讨论了甲烷浓度以及温度对积炭产生的影响,最后提出了消减积炭的方法。本文的结论对于进一步研究Ni基催化剂在CH₄-CO₂重整制合成气反应中积炭效应的消减有一定的指导意义。     

甲烷催化部分氧化制合成气催化剂的研究进展

天然气是一种前景广阔的清洁燃料,甲烷作为天然气的主要成分,其高效利用具有重要的现实意义。在众多甲烷转化途径中,甲烷催化部分氧化（CPOM）具有能耗低、合成气组分适宜、反应迅速等优势。本文简要介绍了CPOM反应机理,即直接氧化机理和燃烧-重整机理;重点综述了过渡金属、贵金属、双金属和钙钛矿这四类CPOM催化剂的研究现状;分析了反应温度、反应气体碳氧比和反应空速对CPOM反应特性的影响;阐述了积炭和烧结这两种催化剂失活的主要原因及应对措施。根据研究结果可知,通过选取合适的催化剂组分、采用优化的制备方法、精确控制催化剂活性组分分布和微观结构等措施,可以保证更多的有效活性位更稳定地暴露在催化剂表面,以此提高催化性能（包括甲烷转化率、合成气选择性、合成气生成率、反应稳定性等）。最后指出了对CPOM催化剂微观结构的合理设计与可控制备以及对CPOM反应机理的深入研究仍将是今后关注的重点。     

A study of carbon deposition on catalysts during the partial oxidation of methane to synthesis gas

The deposition of carbon on catalysts during the partial oxidation of methane to synthesis gas has been investigated and it has been found that the relative rate of carbon deposition follows the order Ni>Pd>Rh>Ir. Methane decomposition was found to be the principal route for carbon formation over a supported nickel catalyst, and electron micrographs showed that both whisker and encapsulate forms of carbon are present on the catalyst. Negligible carbon deposition occurred on iridium catalysts, even after 200 h.     

Mechanism for the formation of carbon dioxide in the catalytic oxidation of carbon monoxide and methane on silica

The oxidation of carbon monoxide to carbon dioxide is shown to be catalyzed at 850 K or above over almost all lattice oxygen atoms on the surface of silica prepared by the sol-gel method from ethyl orthosilicate under conditions which yield high selectivity to carbon dioxide in the oxidation of methane.     

C-H-O三元热力学图在甲烷重整积炭研究中的研究进展

从热力学的角度对甲烷重整过程中的积炭现象进行了综述研究,分析了C-H-O三元素组分的积炭三角图以及不同甲烷重整形式的非积炭区域,包括了SMR、CDR、POM、TRM以及甲烷在燃料电池电化学阳极室中的重整过程。最后提出了热力学视角下缓解积炭的措施是联合重整能有效地减少积炭,而采用阳极注氧能够改善甲烷燃料电池的积炭现象。     

Suppression of carbon deposition in CO2-reforming of methane on metal sulfide catalysts

The catalytic performance of metal sulfides of Mo and W was studied for the CO₂-reforming of methane by comparing with that of Ni/SiO₂. The sulfide catalysts have lower activity than the Ni/SiO₂ catalyst for this reaction, however, no deactivation due to carbon deposition was observed on the sulfide catalysts. The activity for direct decomposition of CH₄ was much smaller on the sulfides than on supported Ni. The rate equation suggested that, during steady-state reaction, the surface was abundant in adsorbed CO₂ on sulfides, by which direct decomposition of CH₄ should be retarded in addition to their lower activity for this reaction.     

A computational study of the role of chlorine in the partial oxidation of methane by MgO and Li/MgO

We investigate the surface defect chemistry of MgO and Li/MgO paying special attention to the effects of added chloride ions on the active sites in the materials when used as partial oxidation catalysts. We calculate that chloride ions will segregate to the surface of these materials and will be preferentially sited at low coordinate sites. The [LiCl] defect cluster is also calculated to be bound, both of which effects will have a major influence on catalytic properties. From our calculations we also comment on the siting and selectivities of the active sites in MgO and Li/MgO.     

Numerical investigation on the number of active surface sites of carbon catalysts in the decomposition of methane

The number of active sites on the surface of carbon catalysts is an important factor in determining their activity in the decomposition of methane. Although several studies have been performed to identify the nature of these sites, no method has been established to estimate their number. A method is presented to estimate this value, and its effect on hydrogen production is evaluated, along with that of temperature and residence time. For this purpose, the thermocatalytic decomposition of methane is modeled with the inclusion of the number of active sites of the catalyst in the kinetics. The results of the model indicate the high influence of variations of small residence times in this process, and the reduction of this effect at high temperatures. Also, the effect of the number of surface sites is shown to be more prominent at low residence times and temperatures. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2228–2234, 2014     

国内外甲烷催化部分氧化技术进展

介绍了国内外甲烷催化部分氧化制合成气技术的研究进展。主要工艺包括固定床工艺、流化床工艺和陶瓷膜工艺。此外，在反应器方面，还对两项最新专利技术进行了讨论。最后，提出了甲烷催化部分氧化制合成气技术的发展趋势，为我国在天然气利用方面的技术开发提供了参考和依据。     

Investigation on the structure and the oxidation activity of the solid carbon produced from catalytic decomposition of methane

The structure and the oxidation activity of the solid carbon produced from catalytic decomposition of methane at different temperatures were investigated using TEM, XRD, Raman and TPO techniques. The results show that the graphitization degree of the solid carbon is increased with decomposition reaction temperature. The addition of ethylene or acetylene to methane can change the growth way of the solid carbon and decrease their graphitization degree. The average oxidation temperature of the solid carbon has a close relationship with the corresponding graphitization degree. The addition of ethylene or acetylene to methane can decrease the average oxidation temperature of the solid carbon.