المؤلفون: Liu, Peng, Wei, Gaoling, He, Hongping, Liang, Xiaoliang, Chen, Hanlin, Xi, Yunfei, Zhu, Jianxi

مصطلحات موضوعية: Chemistry, Materials Science, Physics, Cu and Mn oxides, Formaldehyde, Catalytic oxidation, Deactivation, Regeneration, Physical, Coatings & Films, Applied, Condensed Matter, VOLATILE ORGANIC-COMPOUNDS, ROOM-TEMPERATURE OXIDATION, BIRNESSITE-TYPE MNO2, IN-SITU, GASEOUS FORMALDEHYDE, CO OXIDATION, PERFORMANCE, ADSORPTION, COMBUSTION, VOCS

الوصف: The emission of volatile organic compounds (VOCs) from industrial and commercial processes is detrimental to human health and the environment. Though numerous catalysts have been reported to eliminate the pollution of VOCs, their deactivation and regeneration are still largely unknown. In this study, the prepared palygorskite-supported Cu-Mn oxides displays slight decrease of catalytic activity in the initial stage of formaldehyde oxidation. After the thermal treatment of spent catalyst at 400 degrees C, the catalytic activity is partially recovered. A deactivation and regeneration mechanism is proposed, based on the stability test and the comprehensive characterizations of fresh and spent catalysts. The accumulation of formate species and the depletion of oxygen on the surface of Cu-Mn oxides are responsible for the decline of activity. Thermal treatment of deactivated catalyst at 400 degrees C recovers the catalytic activity because it gasifies the carbonaceous intermediates and replenishes surface oxygen. The obtained results will be of great significance for the application of transition metal oxide-based catalysts in the abatement of VOCs.

العلاقة: APPLIED SURFACE SCIENCE; http://ir.gig.ac.cn/handle/344008/53289Test

الإتاحة: https://doi.org/10.1016/j.apsusc.2018.09.070Test
http://ir.gig.ac.cn/handle/344008/53289Test

المؤلفون: Wei, Gaoling, Liu, Peng, Chen, Dong, Chen, Tianhu, Liang, Xiaoliang, Chen, Hanlin

مصطلحات موضوعية: Chemistry, Materials Science, Mineralogy, Halloysite, Supported manganese oxides, Manganese precursor, Thermal catalytic oxidation, Structure-activity relationship, Physical, Multidisciplinary, BIRNESSITE-TYPE MNO2, TOLUENE OXIDATION, NANOTUBES, PALYGORSKITE, PERFORMANCE, MORPHOLOGY, COMBUSTION, COMPOSITE, EFFICIENT, MINERALS

الوصف: Mn-based catalysts have been widely studied for the oxidation of volatile organic compounds (VOCs) and appear to be the most active catalysts among the transition metal oxides. In this study, manganese oxides are supported on halloysite, a nanoscale and porous clay mineral, by an impregnation method using manganese nitrate, manganese acetate, and potassium permanganate as precursors. The nitrate results in scattered 35-249 nm agglomerates of pyrolusite (beta-MnO2) on the external surface of the halloysite nanotubes; the acetate produces hausmannite (Mn3O4) particles with sizes of 15-40 nm dispersed on the external surface, while the permanganate creates nanoparticles and agglomerates of amorphous K-containing MnO2 on the external surface as well as in the lumen. These differences in structure and distribution are related to the oxidizability of the precursor, surface charge and the cylindrical lumen of halloysite, and the interaction between manganese ions (Mn2+ or MnO4-) and the surface groups of halloysite (Si-O-Si or Al-OH). The obtained samples were tested for the thermal catalytic oxidation of formaldehyde. The halloysite-supported manganese oxide with the permanganate precursor exhibits the best activity and achieves 90% of CO2 generation at 149 degrees C. The activity of formaldehyde oxidation is positively correlated to the reducibility, which depends on the phase, oxidation state, and dispersion of manganese oxides. This study illuminates the constraint of the manganese precursor on halloysite-supported manganese oxides for the thermal catalytic oxidation of formaldehyde and will be beneficial for the development of transition metal oxide-based catalysts in the abatement of VOCs.

العلاقة: APPLIED CLAY SCIENCE; http://ir.gig.ac.cn/handle/344008/48119Test

الإتاحة: https://doi.org/10.1016/j.clay.2019.105280Test
http://ir.gig.ac.cn/handle/344008/48119Test

المؤلفون: Fan, Guijun, 郭雅悰, Chai, Shaohua, Zhang, Le, Guan, Jian, Ma, Guojun, Han, Ning, Chen, Yunfa

المساهمون: Han, Ning, Chen, Yunfa

مصطلحات موضوعية: 8-MnO 2, Ozone oxidation, HCHO oxidation, BIRNESSITE-TYPE MNO2, CATALYTIC-OXIDATION, ROOM-TEMPERATURE, MANGANESE-DIOXIDE, DECOMPOSITION, OZONE, PERFORMANCE, ALPHA-MNO2, BETA-MNO2, PT/TIO2, Environmental Sciences & Ecology, Environmental Sciences, 二类/Q1

الوصف: Nowadays, it is still a challenge to prepared high efficiency and low cost formaldehyde (HCHO) removal catalysts in order to tackle the long-living indoor air pollution. Herein, 8MnO2 is successfully synthesized by a facile ozonation strategy, where Mn2 + is oxidized by ozone (O3 ) bubble in an alkaline solution. It presents one of the best catalytic properties with a low 100% conversion temperature of 85 degrees C for 50 ppm of HCHO under a GHSV of 48,000 mL/(g center dot hr). As a comparison, more than 6 times far longer oxidation time is needed if O3 is replaced by O2 . Characterizations show that ozonation process generates a different intermediate of tetragonal fi-HMnO2 , which would favor the quick transformation into the final product 8-MnO2 , as compared with the relatively more thermodynamically stable monoclinic y-HMnO2 in the O2 process. Finally, HCHO is found to be decomposed into CO2 via formate, dioxymethylene and carbonate species as identified by room temperature insitu diffuse reflectance infrared fourier transform spectroscopy. All these results show great potency of this facile ozonation routine for the highly active 8-MnO2 synthesis in order to remove the HCHO contamination. (c) 2024 The Research Center for Eco-Environmental Sciences, Chinese Academy of

العلاقة: JOURNAL OF ENVIRONMENTAL SCIENCES; http://dspace.imech.ac.cn/handle/311007/94537Test; http://dspace.imech.ac.cn/handle/311007/94538Test

الإتاحة: https://doi.org/10.1016/j.jes.2023.04.021Test
http://dspace.imech.ac.cn/handle/311007/94537Test
http://dspace.imech.ac.cn/handle/311007/94538Test

المؤلفون: Fan, Guijun, Guo, Yacong, Chai, Shaohua, Zhang, Le, Guan, Jian, Ma, Guojun, Han, Ning, Chen, Yunfa

مصطلحات موضوعية: 8-MnO 2, Ozone oxidation, HCHO oxidation, BIRNESSITE-TYPE MNO2, CATALYTIC-OXIDATION, ROOM-TEMPERATURE, MANGANESE-DIOXIDE, DECOMPOSITION, OZONE, PERFORMANCE, ALPHA-MNO2, BETA-MNO2, PT/TIO2, Environmental Sciences & Ecology, Environmental Sciences

الوصف: Nowadays, it is still a challenge to prepared high efficiency and low cost formaldehyde (HCHO) removal catalysts in order to tackle the long-living indoor air pollution. Herein, 8MnO2 is successfully synthesized by a facile ozonation strategy, where Mn2 + is oxidized by ozone (O3 ) bubble in an alkaline solution. It presents one of the best catalytic properties with a low 100% conversion temperature of 85 degrees C for 50 ppm of HCHO under a GHSV of 48,000 mL/(g center dot hr). As a comparison, more than 6 times far longer oxidation time is needed if O3 is replaced by O2 . Characterizations show that ozonation process generates a different intermediate of tetragonal fi-HMnO2 , which would favor the quick transformation into the final product 8-MnO2 , as compared with the relatively more thermodynamically stable monoclinic y-HMnO2 in the O2 process. Finally, HCHO is found to be decomposed into CO2 via formate, dioxymethylene and carbonate species as identified by room temperature insitu diffuse reflectance infrared fourier transform spectroscopy. All these results show great potency of this facile ozonation routine for the highly active 8-MnO2 synthesis in order to remove the HCHO contamination. (c) 2024 The Research Center for Eco-Environmental Sciences, Chinese Academy of

العلاقة: JOURNAL OF ENVIRONMENTAL SCIENCES; http://dspace.imech.ac.cn/handle/311007/94536Test

الإتاحة: https://doi.org/10.1016/j.jes.2023.04.021Test
http://dspace.imech.ac.cn/handle/311007/94536Test

المؤلفون: Fan, Guijun, Guo, Yacong, Chai, Shaohua, Zhang, Le, Guan, Jian, Ma, Guojun, Han, Ning, Chen, Yunfa

مصطلحات موضوعية: 8-MnO 2, Ozone oxidation, HCHO oxidation, BIRNESSITE-TYPE MNO2, CATALYTIC-OXIDATION, ROOM-TEMPERATURE, MANGANESE-DIOXIDE, DECOMPOSITION, OZONE, PERFORMANCE, ALPHA-MNO2, BETA-MNO2, PT/TIO2, Environmental Sciences & Ecology, Environmental Sciences

الوصف: Nowadays, it is still a challenge to prepared high efficiency and low cost formaldehyde (HCHO) removal catalysts in order to tackle the long-living indoor air pollution. Herein, 8MnO2 is successfully synthesized by a facile ozonation strategy, where Mn2 + is oxidized by ozone (O3 ) bubble in an alkaline solution. It presents one of the best catalytic properties with a low 100% conversion temperature of 85 degrees C for 50 ppm of HCHO under a GHSV of 48,000 mL/(g center dot hr). As a comparison, more than 6 times far longer oxidation time is needed if O3 is replaced by O2 . Characterizations show that ozonation process generates a different intermediate of tetragonal fi-HMnO2 , which would favor the quick transformation into the final product 8-MnO2 , as compared with the relatively more thermodynamically stable monoclinic y-HMnO2 in the O2 process. Finally, HCHO is found to be decomposed into CO2 via formate, dioxymethylene and carbonate species as identified by room temperature insitu diffuse reflectance infrared fourier transform spectroscopy. All these results show great potency of this facile ozonation routine for the highly active 8-MnO2 synthesis in order to remove the HCHO contamination. (c) 2024 The Research Center for Eco-Environmental Sciences, Chinese Academy of

العلاقة: JOURNAL OF ENVIRONMENTAL SCIENCES; http://dspace.imech.ac.cn/handle/311007/94491Test

الإتاحة: https://doi.org/10.1016/j.jes.2023.04.021Test
http://dspace.imech.ac.cn/handle/311007/94491Test