Volatile organic compounds（VOCs） are a major component in air pollutants and pose great risks to both human health and environmental protection. Currently, VOC abatement in industrial applications is through the use...Volatile organic compounds（VOCs） are a major component in air pollutants and pose great risks to both human health and environmental protection. Currently, VOC abatement in industrial applications is through the use of activated carbons as adsorbents and oxide-supported metals as catalysts. Notably, activated carbons easily adsorb water, which strongly hinders the adsorption of VOCs; conventional oxides typically possess relatively low surface areas and random pores, which effectively influence the catalytic conversion of VOCs. Zeolites, in contrast with activated carbons and oxides, can be designed to have very uniform and controllable micropores, in addition to tailored wettability properties, which can favor the selective adsorption of VOCs. In particular, zeolites with selective adsorptive properties when combined with catalytically active metals result in zeolite-supported metals exhibiting significantly improved performance in the catalytic combustion of VOCs compared with conventional oxide-supported catalysts. In this review, recent developments on VOC abatement by adsorptive and catalytic techniques over zeolite-based materials have been briefly summarized.展开更多
Zeolites are crystalline aluminosilicates with three‐dimensional microporous structures. They have been used as ion‐exchangers, catalysts, and adsorbents in various fields such as oil refining, petro‐chemistry, agr...Zeolites are crystalline aluminosilicates with three‐dimensional microporous structures. They have been used as ion‐exchangers, catalysts, and adsorbents in various fields such as oil refining, petro‐chemistry, agriculture, and water and wastewater treatment. Their wide use is because of their many beneficial properties, such as framework and compositional flexibilities, physical and hydro‐thermal stabilities, non‐toxicity, high surface areas, exchangeable cations, and good cost‐benefit ratios. Although many zeolite applications depend on their microporous structures, this can cause diffusional constraints for bulky reactant and product molecules. There have been many efforts to overcome the intrinsic limitations of conventional zeolites by preparing nanosized and hierarchi‐cally structured zeolites. As a result of these efforts, several strategies have been established and the use of new zeolitic materials in various catalytic and adsorptive reactions has been investigated. Longer lifetimes, high catalytic performances, and postponed coking and catalyst deactivation can be achieved using hierarchical and nanosized zeolites. The aim of this review is to provide an over‐view of the enhanced properties of hierarchical and nanosized zeolites, and recent development methods for their synthesis. The advantages and disadvantages of each route are discussed, and the catalytic applications of nanozeolites and zeolites with secondary porosity, and a comparison with conventional zeolites, are briefly presented.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(2015XZZX004-04)Zhejiang Provincial Natural Science Foundation(LR15B030001)~~
文摘Volatile organic compounds（VOCs） are a major component in air pollutants and pose great risks to both human health and environmental protection. Currently, VOC abatement in industrial applications is through the use of activated carbons as adsorbents and oxide-supported metals as catalysts. Notably, activated carbons easily adsorb water, which strongly hinders the adsorption of VOCs; conventional oxides typically possess relatively low surface areas and random pores, which effectively influence the catalytic conversion of VOCs. Zeolites, in contrast with activated carbons and oxides, can be designed to have very uniform and controllable micropores, in addition to tailored wettability properties, which can favor the selective adsorption of VOCs. In particular, zeolites with selective adsorptive properties when combined with catalytically active metals result in zeolite-supported metals exhibiting significantly improved performance in the catalytic combustion of VOCs compared with conventional oxide-supported catalysts. In this review, recent developments on VOC abatement by adsorptive and catalytic techniques over zeolite-based materials have been briefly summarized.
文摘Zeolites are crystalline aluminosilicates with three‐dimensional microporous structures. They have been used as ion‐exchangers, catalysts, and adsorbents in various fields such as oil refining, petro‐chemistry, agriculture, and water and wastewater treatment. Their wide use is because of their many beneficial properties, such as framework and compositional flexibilities, physical and hydro‐thermal stabilities, non‐toxicity, high surface areas, exchangeable cations, and good cost‐benefit ratios. Although many zeolite applications depend on their microporous structures, this can cause diffusional constraints for bulky reactant and product molecules. There have been many efforts to overcome the intrinsic limitations of conventional zeolites by preparing nanosized and hierarchi‐cally structured zeolites. As a result of these efforts, several strategies have been established and the use of new zeolitic materials in various catalytic and adsorptive reactions has been investigated. Longer lifetimes, high catalytic performances, and postponed coking and catalyst deactivation can be achieved using hierarchical and nanosized zeolites. The aim of this review is to provide an over‐view of the enhanced properties of hierarchical and nanosized zeolites, and recent development methods for their synthesis. The advantages and disadvantages of each route are discussed, and the catalytic applications of nanozeolites and zeolites with secondary porosity, and a comparison with conventional zeolites, are briefly presented.
