Research progress on preparation of cerium-based oxide catalysts with specific morphology and their application for purification of diesel engine exhaust

The elimination of pollutants from diesel exhaust has received widespread research attention as they cause serious air pollution and pose a threat to human health.Catalytic post-treatment technology is one of the most effective and universal technologies to treat diesel exhaust pollutants.The design and development of efficient and low-cost catalysts is the key factor to realize the wide application of catalytic post-treatment technology.Cerium(Ce)-based oxides with specific morphologies are widely used to eliminate pollutants in diesel vehicle exhaust due to their unique physical and chemical properties,such as high catalytic activity,low cost and non-toxicity.In this review,the preparation methods of Cebased oxide materials with specific morphologies,such as nanoparticles,nanocubes,nanorods,nanofibers,and multi-stage pores,are introduced in detail,and the research progress on using these catalysts for the removal of carbon monoxide,hydrocarbons,soot particles,nitrogen oxides,and other pollutants from diesel exhaust is reviewed in detail.Finally,the unresolved issues associated with using Ce-based oxide catalysts with a specific morphology to catalytically remove pollutants from diesel exhaust are highlighted,and future application prospects and development directions are discussed.

纳米纤维状金属氧化物催化剂的制备及其催化净化大气污染物的研究进展

随着大气污染的日益严峻和人们环保意识的提高,大气污染物的治理已经成为环保领域的研究热点.目前,催化净化技术是处理大气污染物最有效、应用最广泛的技术之一,其中高效、低成本的催化剂研发是催化净化技术应用的关键性因素.纳米纤维状金属氧化物催化剂因其比表面积大、传质能力强,接触效率高等独特的理化性质,被广泛应用于各类大气污染物的催化净化反应中.本文介绍了纤维状金属氧化物催化剂的制备方法,如静电纺丝法、水热法/溶剂热和其他方法并对相关的制备原理进行了描述;同时详细总结了近年来纳米纤维状金属氧化物催化剂在催化净化CO、VOCs、炭烟颗粒、NOx及其他大气污染物的研究进展.最后,对纳米纤维状金属氧化物催化剂在催化净化大气污染物中存在的问题和未来发展趋势进行了总结和展望.

K-modified MnO_(δ)catalysts with tunnel structure and layered structure:Facile preparation and catalytic performance for soot combustion

Air pollution from particulate matter produced by incomplete combustion of diesel fuel has become a serious environmental pollution problem,which can be addressed by catalytic combustion.In this work,a series of K-modified MnO_(δ)catalysts with different microstructures were synthesized by the hydrothermal method,the relationship between structure of the catalysts and their catalytic performance for soot combustion was studied by characterization techniques and density functional theory(DFT)calculations.Results showed that the prepared catalysts had good catalytic performance for soot combustion and could completely oxidize soot at temperatures below 400℃.The cryptomelane-type K_(2−x)Mn_(8)O_(16)(K-OMS-2)with tunnel structure had excellent NO oxidation capacity and abundance of Mn^(4+)ions(Mn^(4+)/Mn^(3+)=1.24)with good redox ability,it demonstrated better soot combustion performance than layered birnessite-type K_(2)Mn_(4)O_(8)(K-OL-1).The T_(10),T_(50),T_(90)temperatures of KOMS-2 were 269,314,346℃,respectively.The K-OMS-2 catalyst also showed excellent stability after five catalytic cycles,with T_(10),T_(50),T_(90)values holding in the ranges of 270±2,316±2,348±3℃,respectively.

铈基氧化物催化燃烧柴油机炭烟颗粒的性能及机理研究进展

随着环保法规的日益严格和人们环保意识的提高,柴油车尾气污染物中的炭烟颗粒对环境的严重污染引起了人们广泛的关注.利用催化净化技术实现炭烟颗粒的消除是目前最有效的途径之一,其中高活性催化剂的研发是决定该技术广泛应用的关键因素之一.近年来,铈基氧化物催化剂因其良好的氧化还原性能、适当的表面酸性以及较高的储/释氧容量而被广泛用于柴油机尾气炭烟颗粒的催化燃烧领域.研究铈基氧化物催化剂在炭烟催化燃烧反应高活性的本质,有助于了解炭烟颗粒催化燃烧过程的基本原理,为现有催化剂的优化和新型催化剂的设计提供科学指导.本文总结了近年来铈基氧化物催化剂材料在催化柴油机炭烟燃烧中的研究进展,主要包括单一氧化铈催化剂和稀土金属、过渡金属、碱(碱土)金属及贵金属改性的铈基氧化物催化剂.同时,对上述催化剂的反应机理进行了总结.最后,提出了铈基氧化物催化剂在催化柴油机炭烟燃烧中存在的问题并对其发展前景进行了展望.

钙钛矿氧化物催化剂的制备及其催化燃烧炭烟颗粒性能的研究进展

柴油机尾气中炭烟颗粒是城市雾霾的主要来源之一,严重污染环境和危害人体的健康,利用催化净化技术实现炭烟颗粒的消除是目前最有效的途径之一,其中高活性催化剂的研发是决定该技术广泛应用的关键因素之一.近年来,钙钛矿氧化物催化剂因具有高活性、低成本、高稳定性等优点,在炭烟颗粒催化燃烧中成为研究的热点.本文重点总结了近年来常用钙钛矿氧化物催化剂的制备方法,如溶胶-凝胶法、模板法、共沉淀法、水热合成法、固相合成法等,同时对在炭烟颗粒催化燃烧中具有高活性的钙钛矿氧化物催化剂,如Co基钙钛矿、Mn基钙钛矿、Fe基钙钛矿、Ti基钙钛矿等催化剂进行了详细的阐述,并对钙钛矿氧化物催化剂在催化柴油机炭烟颗粒燃烧的发展前景进行了展望.

锰基催化剂在催化柴油炭烟燃烧中的应用

柴油机排放的炭烟颗粒引起了严重的环境污染并对人体健康造成了极大的危害,引起人们的广泛关注。目前,催化净化技术是控制柴油机尾气炭烟颗粒排放最有效和研究最广泛的技术手段之一,其中高性能催化剂的研发是催化净化技术应用最为关键的因素。本文总结了近年来锰基催化剂材料在催化柴油机炭烟燃烧中的研究进展,重点介绍了单组分锰基催化剂、复合结构锰基氧化物催化剂、固定结构锰基氧化物催化剂(钙钛矿型、尖晶石型、水滑石型)等的研究进展,并简述了锰基催化剂材料在同时消除炭烟颗粒和氮氧化物方面的研究进展。最后,提出了锰基催化剂在催化柴油机炭烟燃烧中存在的问题并对其发展前景进行了展望。

Research advances of rare earth catalysts for catalytic purification of vehicle exhausts-Commemorating the 100th anniversary of the birth of Academician Guangxian Xu

Nowadays,air pollution has become a prominent environmental problem and has attracted much attention.With the increase of vehicle retention quantity,the exhaust emissions have become the main sources of air pollution.To reduce pollution and hazards,vehicle exhaust emission regulations are becoming stricter and stricter,which puts forward higher requirements for purification of vehicle exhausts.At present,rare earths have been widely applied in vehicle exhaust purification because of their good catalytic performance,which is attributed to their unique 4 f electron layer structure occupied without full electrons,excellent oxygen storage/release capacity and redox ability.In this paper,the current status of rare earth catalysts and application of rare earth in different fuel vehicle exhaust catalysts,including three-way catalysts(TWCs)for gasoline vehicles,diesel exhaust catalysts for different pollutants(particulate matter(PM),NOx,CO and HC)and catalysts for new energy vehicles with different fuels,are summarized in detail.Meanwhile,the corresponding mechanisms and the role of rare earth in vehicle exhaust catalysts are also simultaneously described.Furthermore,the challenges and development directions of rare earth catalysts for the purification of vehicle exhausts are also proposed.