钴基费托合成催化剂载体表面改性及失活机理研究进展

综述了费托合成钴基催化剂载体材料表面改性及催化剂失活机理的研究进展。指出对载体表面进行预处理可以调节载体和钴物种之间的相互作用,进而影响费托合成催化剂的还原度、分散度和催化性能。同时利用氧掺杂和氮掺杂的方法改变碳材料表面的化学性质,可以提高锚定钴物种的能力。钴基催化剂的失活是费托合成反应的主要问题之一,针对失活机理的研究可以提高钴基催化剂的稳定性。由于钴基催化剂合成的成本较高,因此通过对载体的表面改性和催化剂失活机理的研究来改善钴基催化剂的活性、稳定性以及产物的选择性是值得深入研究的课题。     

掺杂碳材料的制备及其负载贵金属在催化加氢反应中的应用研究进展

贵金属加氢催化剂广泛应用于精细化学品、药物和功能材料的合成中,以改进催化剂制备方法来提高其活性、选择性或稳定性一直是该领域研究热点。而采用掺杂碳材料作为催化剂载体是改善贵金属催化剂加氢性能的一种有效途径。文章系统总结了掺氮、掺硫及其它掺杂碳材料的制备方法,介绍了不同制备方法对碳材料中杂原子含量、物化性质的影响;并概述了掺杂碳载体负载贵金属催化剂在硝基苯类化合物、共轭羰基、苯酚催化加氢以及在加氢脱卤等反应中的应用情况,掺杂催化剂均展现出了优异的催化性能。     

氮掺杂碳材料的制备及其在催化领域中的应用

氮掺杂碳材料以其独特的性质在催化研究领域具有广泛的应用。氮掺杂过程可引入缺陷位及氮物种,改善催化剂的物理化学性质、酸碱性和浸润性,并与活性物种产生相互作用,提升催化性能。本文从氮掺杂碳材料的制备及其在催化领域中的应用展开综述。常见的氮掺杂碳材料主要利用含氮前驱体,通过后合成法、原位合成法、催化生长法和模板法进行制备。通过改变前驱体种类、处理条件等制备参数,可实现孔道结构、氮物种类型、氮物种掺杂量及其与活性物种相互作用等性质的调变。开发大规模经济环保的制备方法,推动对缺陷构筑以及氮物种与活性组分相互作用机制的研究,是未来重要的研究方向。氮掺杂碳材料在催化领域表现出优越的性能,有望成为催化剂开发的前瞻领域,推动相关工业技术的进步。     

铁基费托合成催化剂研究进展

综述了近十年来铁基催化剂在费托合成反应中的研究进展,探讨了铁基催化剂活性组分的确定及影响铁基催化剂活性组分的因素,对比了3种催化剂制备方法（熔融法、沉淀法、负载法）和5种催化剂载体（氧化物、分子筛、碳材料、双孔材料和核壳材料）对费托合成反应性能的影响,从反应活性、选择性和反应稳定性3个方面阐述了助催化剂在费托合成反应中的作用。分析认为：碳化铁是铁基费托合成催化剂的活性组分;在铁基催化剂的制备过程中,选择适宜的制备方法、载体、助催化剂,可以达到提高费托合成反应活性、目的产物选择性和反应稳定性的效果。提出合成特定结构碳化铁、进一步研究铁基催化剂反应机理仍是未来研究的重点。     

氮掺杂碳材料中氮物种的调控及其负载Pd催化剂在加氢反应中的应用

介绍了氮掺杂碳材料中氮物种的调控方法,通过改变氮源添加量、氮源种类和焙烧温度能够对氮含量进行调控。通过原位合成法、后处理法以及改变反应条件(主要指焙烧温度和焙烧时间)能够对氮类型进行调控。原位合成法和后处理法制备的氮掺杂碳材料分别以石墨型氮和吡啶型氮为主。随着焙烧温度升高,焙烧时间延长,氮含量逐渐降低,石墨型氮占比上升。氮掺杂碳载体(N-C)负载Pd催化剂(Pd/N-C)在直接加氢和液相加氢脱氯反应中的应用方面,介绍了氮掺杂碳载体通过自身特性及其对Pd的锚定作用和电子影响来提高加氢性能,综合分析发现,氮掺杂碳载体增强了Pd/N-C催化剂与溶剂以及反应物的相互作用力;对Pd的锚定作用加强,提高了Pd/N-C催化剂的分散度和稳定性并改变了Pd0/Pd~(2+)的比例。     

负载型金属催化剂的制备技术及其在废水处理中的应用研究进展

综述了现阶段去除水中特征污染物的催化剂的主要制备方法和应用情况,现有负载型金属催化剂制备工艺存在表面金属离子状态不稳定、不耐负荷等不足。为了进一步提高催化剂性能,研究了氮掺杂碳材料包覆过渡金属催化剂,发现氮掺杂碳材料能形成新的活性位点,表现出类金属的性质,而且能提高催化剂的亲水性。采用后包覆法制备的氮掺杂碳材料因包裹金属离子能改善负载型金属催化剂的耐化学药品腐蚀性和稳定性,在催化领域中具有更加广阔的应用前景。     

高选择性钴基费托合成催化剂的研究进展

费托合成反应催化剂的开发是费托合成技术研究和产业化的关键,钴基费托合成催化剂是制备长链烃类的较理想的催化剂之一,具有良好的工业应用前景。对催化剂预处理方法、载体、助剂及制备方法等方面进行了介绍,分析了钴基催化剂在费托合成反应中提高反应活性及选择性的作用,并指出选择适宜的钴基催化剂制备方法可以较好地提高费托合成反应转化率、选择性及稳定性。     

氮掺杂碳纳米材料在氧还原反应催化剂中的研究进展

长期以来,碳材料负载高分散的铂催化剂及其合金材料一直是商业化质子交换膜燃料电池（PEMFC）中氧还原反应和氢氧化反应十分有效的催化剂。但由于Pt基催化剂成本高、电化学条件下稳定性差、易CO中毒以及氧还原反应（ORR）动力学迟缓等一系列问题,阻碍了其在燃料电池中的进一步应用和大规模生产。相比之下,氮掺杂碳纳米材料具有低成本、高活性、高稳定性、环境友好等特点,这些优异的性能使其在燃料电池领域有着广阔的应用前景。结合近几年国内外研究现状,综述了原位掺杂法、后掺杂合成法和直接热解法等3种氮掺杂碳纳米材料的制备方法,并分析了各自的优点和不足之处,及其作为ORR催化剂的研究进展。最后,对未来氮掺杂碳纳米材料催化剂研究的主要发展方向进行了展望。     

氮掺杂碳材料负载金属纳米颗粒的应用研究

把金属纳米粒子沉积在氮掺杂碳载体上可以使其具有各种新型的有机催化剂。本文综述了近年来氮掺杂碳载体负载金属纳米材料在近些年的研究进展,指出了新型催化剂材料制备和性能研究具有重要的应用潜力,展望了其未来发展前景。     

氮掺杂改性碳材料的研究进展

通过对碳材料进行氮掺杂改性,可强化碳材料的性能从而拓宽其应用领域。总结了近年来国内外对氮掺杂改性碳材料的研究进展,详细介绍了利用活化法、水热法、化学气相沉积法、模板法、溶胶-凝胶法和后处理法制备氮掺杂改性碳材料的方法,对其在催化剂、吸附材料、超级电容器、储氢等领域上的应用作了详细介绍,对氮掺杂改性碳材料的发展趋势进行了展望。     

直接甲醇燃料电池中碳基载体材料的研究进展

甲醇氧化电催化剂是决定直接甲醇燃料电池（direct methanol fuel cells, DMFCs）性能、寿命与成本的关键。为获得高功率密度和低生产成本的DMFCs,设计合成具有组成、结构、形貌可控的阳极催化剂备受关注。阳极催化剂的颗粒尺寸、粒径分布、形貌结构、稳定性、分散性以及催化活性都和负载它的载体息息相关,而碳基载体材料由于其优异的性能被广泛应用于DMFCs领域。本文分别介绍了酸性环境和碱性环境中甲醇氧化反应的机理,然后对不同形式的碳基载体材料,例如炭黑、介孔碳、碳纳米材料、氧功能化碳、杂原子掺杂碳、以及金属氧化物改性碳作为催化剂载体在DMFCs领域中的应用进行了综述,最后对DMFCs的发展趋势进行了展望。     

Cobalt supported on carbon nanotubes — A promising novel Fischer–Tropsch synthesis catalyst

An extensive study of Fischer–Tropsch synthesis (FTS) on carbon nanotubes (CNT) supported and γ–alumina-supported cobalt catalysts with different amounts of cobalt are reported. Up to 40 wt.% of cobalt is added to the supports by the impregnation method. The effect of the support on the reducibility of the cobalt oxide species, dispersion of the cobalt, average cobalt clusters size, water–gas shift (WGS) activity and activity and selectivity of FTS is investigated. Using carbon nanotubes as cobalt catalyst support was found to cause the reduction temperature of cobalt oxide species to shift to lower temperatures. The strong metal-support interactions are reduced to a large extent and the reducibility of the catalysts improved significantly. CNT aided in well dispersion of metal clusters and average cobalt clusters size decreased. Results are presented showing that the hydrocarbon yield obtained by inventive CNT supported cobalt catalyst is surprisingly much larger than that obtained from cobalt on alumina supports. The maximum concentration of active surface Co° sites and FTS activity for alumina and CNT supported catalysts are achieved at 34 wt.% and 40 wt.% cobalt loading respectively. CNT caused a slight decrease in the FTS product distribution to lower molecular weight hydrocarbons.     

Manipulating metal-support interactions of metal catalysts for Fischer-Tropsch synthesis

For supported metal catalyst systems,the impact on catalysis originates from the interaction between metal nanoparticles and their support.Metal-support interactions (MSI) can change electronic properties,geometric morphologies,or chemical compositions of metal nanoparticles to make active sites have specific properties and catalytic activities.Fischer-Tropsch synthesis (FTS) is one of the most effective ways to convert cheap non-petroleum-based carbon sources into high value-added chemicals or ultra-clean liquid fuels.In this review,we summarize and classify the impact of MSI on the catalytic activity,selectivity and stability of FTS catalysts.The strategies to tune MSI are introduced in detail,and the recent development of high-efficiency FTS catalysts through the manipulation of SMI strategies has been high-lighted.It is emphasized that the active metal sites,which are endowed with special functions by MSI,can change the strength of adsorption bond of adsorbates,consequently controlling the product distribution.     

碳材料用于低温选择性催化还原脱硝的研究进展

选择性催化还原技术是目前消除NOx的主流技术。碳材料作为自然界广泛存在的一种材料,具有比表面积大、化学稳定性好、结构可调控和表面可改性等优点,广泛应用于低温选择性催化还原反应。综述不同类型碳材料包括活性炭、活性炭纤维、碳纳米管、石墨烯和多孔碳在低温选择性催化还原中的应用,介绍碳材料作为活性组分和催化剂载体的使用情况,讨论表面化学改性对催化NOx性能的影响,阐述碳材料在加快反应速率和提升催化剂抗硫中毒方面的独特性能,并展望碳材料作为新型载体材料在低温选择性催化还原中的应用前景。     

Iron catalyst supported on carbon nanotubes for Fischer-Tropsch synthesis: Effects of Mo promotion

Our studies on the application of carbon nanotubes (CNTs) as support have shown that iron catalysts supported on CNTs are active and selective catalysts for Fischer-Tropsch synthesis (FTS). However, these catalysts experienced deactivation as a result of active site agglomerations. In order to control the agglomeration of active site, which is an important step in developing a novel catalyst supported on carbon-based supports, the effects of Mo promotion on deactivation behavior of iron catalysts supported on CNTs were studied. In this work the properties and catalytic performance of unpromoted iron catalysts were compared with a promoted catalyst with different Mo contents (0.5, 1, 5, and 12 wt%). Based on TEM and XRD analyses, promotion of the catalysts with Mo resulted in production of smaller metal particles compared to the unpromoted iron catalyst. According to XRD analysis, Mo species were deposited in their amorphous structure. TPR analyses showed that addition of Mo increased reduction temperature significantly. Based on TEM and XRD analyses, the particle size of the iron oxides in the unpromoted catalyst increased from 16 to 25 nm under FT operating conditions, while the particle size of the iron oxide in the Mo promoted catalysts (∼12-14 nm) did not change noticeably under the same operating conditions. Activity, selectivity and stability of the unpromoted and Mo promoted catalysts showed that addition of 0.5-1 wt% Mo resulted in a more stable catalyst. Higher contents of Mo (5 and 12 wt%) decreased the activity of the catalysts due to catalytic site coverage and lower extent of reduction. Mo promotion (0.5-12 wt%) increased the selectivity of the catalysts toward lighter hydrocarbons. The promotion of the iron catalyst with 0.5 wt% of Mo stabilized the activity of the catalyst with minimal increase (2%) in methane selectivity.     

多孔碳纳米球及其负载金属催化剂的研究进展

多孔碳纳米球由于可实现尺寸、形貌、孔结构以及表面基团等的可控合成制备,其负载/镶嵌的金属粒子又兼具高活性和高热稳定性等,在多相催化领域中受到越来越多的关注。本文追溯了多孔碳纳米球形貌调控的发展历程及其负载金属催化剂在催化反应领域中的应用。归纳了不同形貌的多孔碳纳米球及其制备方法和原理,详细对比了各个方法的优缺点;阐述了多孔碳纳米球负载金属催化剂的性能和碳球结构与形貌之间的构效关系;总结了目前碳球作为催化剂载体亟需解决的问题是碳球的多孔结构及其负载尺寸可控和空间匀称分布的金属粒子的可控合成,并展望了其发展方向是进一步研究和探索结构可调、经济可行的碳纳米球制备方法,真正实现工业化应用。     

Enhanced methanol electro-oxidation activity of PtRu catalysts supported on heteroatom-doped carbon

A typical heteroatom (nitrogen)-doped carbon materials were successfully synthesized through the carbonization of a hybrid containing traditional carbon black covered by in situ polymerized polyaniline. The nitrogen content onto carbon can be adjusted up to 5.1 at.% by changing the coverage of polyaniline. The effects of nitrogen doping on the surface physical and electrochemical properties of carbon were studied using XPS, XRD and HRTEM, as well as CV and EIS techniques. With increasing nitrogen doping, the carbon structure became more compact, showing curvatures and dislocations in the graphene stacking. The nitrogen-doped carbon also exhibited a higher accessible surface area in electrochemical reactions, and a lower charge transfer resistance at the carbon/electrolyte interface. Moreover, to investigate the influence of nitrogen doping on the electrocatalytic activity of the PtRu/C catalyst, comparisons in CO stripping and methanol oxidation were carried out on PtRu catalysts supported by non-doped and nitrogen-doped carbon. Since the promotional roles of nitrogen doping, including the high electrochemically accessible surface area, the richness of the disordered nanostructures and defects, and the high electron density on N-doped carbon supports, contribute to the synthesis of well-dispersed PtRu particles with high Pt utilization and stronger metal-support interactions, an enhanced catalytic activity for methanol oxidation was obtained in the case of the PtRu/N-C catalyst in comparison with the traditional PtRu/C catalyst.     

炭基材料负载型低温NH3-SCR脱硝催化剂的研究进展

氮氧化物（NO _x ）是主要的大气污染物之一，对人体健康和生态环境造成了严重危害。低温选择性催化还原（SCR）技术是近年来烟气脱硝领域的主要研究方向。炭基材料具有较大的比表面积、发达的孔隙结构等特点，在SCR脱硝方面被广泛用作催化剂载体。本文综述了炭基材料包括活性炭（焦）、活性炭纤维、碳纳米管、石墨烯及碳包覆负载型催化剂在低温NH₃-SCR脱硝领域的研究成果与进展，阐述了表面官能团、反应条件及稀土元素等因素对炭基材料负载型催化剂脱硝性能的影响，并且讨论了炭基材料负载型催化剂的催化反应机理。指出采用多种手段改性催化剂，优化其中低温脱硝性能与稳定性，深入探究催化剂表面反应物种的吸附-活化行为和催化反应路径是炭基材料负载型低温NH₃-SCR催化剂研究的重点。