摘要：由CO和CO_(2)加氢制甲烷是现今氢能储存及燃料和化学品可持续生产的有效途径之一,但目前对该反应过程(尤其是针对CO和CO_(2)混合物加氢)的一些细节尚不明晰。为此,作为前期有关CO和CO_(2)加氢制烃和醇研究工作的补充,本工作对CO和CO_(2),尤其是两者混合物的加氢制甲烷反应过程进行了热力学分析。结果证实,与单独CO或CO_(2)相比,两者混合物加氢制甲烷更为合适,总碳基甲烷收率可作为评估甲烷合成反应过程效率的重要指标。CO加氢的甲烷平衡收率比CO_(2)加氢的高,而CO和CO_(2)混合物加氢的总碳基甲烷平衡收率位于两者之间;对于CO和CO_(2)混合物加氢,尽管CO和CO_(2)的平衡转化率随进料组成不同会有很大的变化,但其总碳基甲烷平衡收率随着原料中CO_(2)/(CO+CO_(2))物质的量比的增大而线形降低。整体上看,在温度低于400℃和压力高于0.1 MPa时,无论是CO、CO_(2)、还是两者混合物的化学计量比加氢,其总碳基甲烷平衡收率均高于85%。这些结果无疑对高效CO和CO_(2)加氢制甲烷催化剂研制及反应过程的设计和操作优化有重要的参考价值。

摘要：采用水热法合成了相同粒径、不同硅铝比的ZSM-5分子筛,并通过浸渍法将Fe基(Fe-Cu-K)催化剂负载于ZSM-5上,系统考察了分子筛硅铝比变化对合成气制烯烃(FTO)反应的影响。结果表明,反应条件、分子筛酸性对CO转化率和低碳烯烃选择性有显著影响。当ZSM-5分子筛硅铝比为50时负载型催化剂有着最高的CO转化率(84.71%)和低碳烯烃选择性(32.08%)。H_2-TPR结果表明,硅铝比为50的Z50/FeCuK中Fe物相的还原度最高。原位漫反射红外光谱(DRIFTS)、热重差热分析(TG-DTA)、X射线粉末衍射(XRD)等结果表明,Z50/FeCuK催化剂表面吸附的碳酸盐和烃类吸附物种最多,且其反应后形成了较多的FeC_x晶相。最后对反应条件进行了优化,结果表明,温度为310℃,H_2/CO(volume ratio)=2和压力为1.0 MPa时FTO的催化性能最优。

摘要：H‐ZSM‐5 zeolite is a typical catalyst for methanol‐to‐olefins(MTO)*** the performance of zeolite catalysts for MTO conversion is related to the actual location of acid sites in the zeolite framework,the catalytic roles of the acid sites in different pore channels of the H‐ZSM‐5 zeolite are not well *** this study,the MTO reaction network,involving the aromatic cycle,alkene cycle,and aromatization process,and also the diffusion behavior of methanol feedstock and olefin and aromatic products at different acid sites in the straight channel,sinusoidal channel,and intersection cavity of H‐ZSM‐5 zeolite was comparatively investigated using density functional theory calculations and molecular dynamic *** results indicated that the aromatic cycle and aromatization process occurred preferentially at the acid sites in the intersection cavities with a much lower energy barrier than that at the acid sites in the straight and sinusoidal *** contrast,the formation of polymethylbenzenes was significantly suppressed at the acid sites in the sinusoidal and straight channels,whereas the alkene cycle can occur at all three types of acid sites with similar energy barriers and ***,the catalytic performance of H‐ZSM‐5 zeolite for MTO conversion,including activity and product selectivity,can be regulated properly through the purposive alteration of the acid site distribution,viz.,the location of Al in the zeolite *** study helps to elucidate the relation between the catalytic performance of different acid sites in the H‐ZSM‐5 zeolite framework for MTO conversion,which should greatly benefit the design of efficient catalyst for methanol conversion.