A series of gold-based catalysts were prepared by deposition precipitation or incipient wetness impregnation on CexZ1-xO2 solid solutions （0.28≤x≤1.00）. The morphological and structural characterization of these c...A series of gold-based catalysts were prepared by deposition precipitation or incipient wetness impregnation on CexZ1-xO2 solid solutions （0.28≤x≤1.00）. The morphological and structural characterization of these catalysts were carried out with X-ray diffraction, trans- mission electron microscopy （TEM） analysis and physical adsorption technique, and their redox properties were studied by temperature programmed reduction using both H2 and CO as probe molecules. Two cycles of oxidation/reduction were carried out in order to evaluate the effects of redox aging and gold sintering on the oxygen exchange capability. As observed with other noble metals, gold enhanced and promoted the ceria reduction at lower temperatures. Reduction by CO was shown to be dependent on the fine dispersion of gold and to be nega- tively affected by the ageing process more than reduction with hydrogen. This might have implications in reactions like water gas shift and CO-PROX which involve CO as a main reactant.展开更多
Propane dehydrogenation(PDH)is an efficient technology for the direct production of propylene.Nevertheless,current PDH catalysts mainly rely on precious Pt or toxic Cr and especially undergo severe coke deposition.Her...Propane dehydrogenation(PDH)is an efficient technology for the direct production of propylene.Nevertheless,current PDH catalysts mainly rely on precious Pt or toxic Cr and especially undergo severe coke deposition.Herein,we report a Ru catalyst decorated by boron species(Ru-3B/Al_(2)O_(3)),which exhibits high catalytic performance for PDH.HAADF-STEM,EELS,and CO-FTIR characterization are used to identify the surface structure of the Ru active component,which shows that the high-energy unsaturated coordination sites,including corners,edges and step atoms for Ru-3B/Al_(2)O_(3),are appropriately modified by BO_(x)species.The encapsulation of high-energy active sites prone to Csingle bondC cracking and deep dehydrogenation leads to higher propylene selectivity(>95%)and strong carbon resistance(kd 0.0007 min)over Ru-3B/Al_(2)O_(3).The XPS and H2-TPR results show that the migration of B species is driven by the reduction of B_(2)O_(3)to B2O2 and that the coating degree of Ru particles is controlled by the chemical valance of Ru species.展开更多
This review shows that relatively simple changes to diet and lifestyle can significantly,and rapidly,reduce the risks associated with coronavirus disease 2019(COVID-19)in terms of infection risk,severity of disease,an...This review shows that relatively simple changes to diet and lifestyle can significantly,and rapidly,reduce the risks associated with coronavirus disease 2019(COVID-19)in terms of infection risk,severity of disease,and even disease-related mortality.A wide range of interventions including regular exercise,adequate sleep,plant-based diets,maintenance of healthy weight,dietary supplementation,and time in nature have each been shown to have beneficial effects for supporting more positive health outcomes with COVID-19,in addition to promoting better overall health.This paper brings together literature from these areas and presents the argument that non-pharmaceutical approaches should not be overlooked in our response to COVID-19.It is noted that,in several cases,interventions discussed result in risk reductions equivalent to,or even greater than,those associated with currently available vaccines.Where the balance of evidence suggests benefits,and the risk is minimal to none,it is suggested that communicating the power of individual actions to the public becomes morally imperative.Further,many lives could be saved,and many harms from the vaccine mandates avoided,if we were willing to embrace this lifestyle-centred approach in our efforts to deal with COVID-19.展开更多
文摘A series of gold-based catalysts were prepared by deposition precipitation or incipient wetness impregnation on CexZ1-xO2 solid solutions （0.28≤x≤1.00）. The morphological and structural characterization of these catalysts were carried out with X-ray diffraction, trans- mission electron microscopy （TEM） analysis and physical adsorption technique, and their redox properties were studied by temperature programmed reduction using both H2 and CO as probe molecules. Two cycles of oxidation/reduction were carried out in order to evaluate the effects of redox aging and gold sintering on the oxygen exchange capability. As observed with other noble metals, gold enhanced and promoted the ceria reduction at lower temperatures. Reduction by CO was shown to be dependent on the fine dispersion of gold and to be nega- tively affected by the ageing process more than reduction with hydrogen. This might have implications in reactions like water gas shift and CO-PROX which involve CO as a main reactant.
基金supported by the National Natural Science Foundations of China(22078007)the Fundamental Research Funds for the Central Universities(JD2108)Innovative Achievement Commercialization Service-Platform of Industrial Catalysis,MIIT.R.M.would like to thank Chemistry and Chemical Engineering Guangdong Laborary for startup funding support(2111001).
文摘Propane dehydrogenation(PDH)is an efficient technology for the direct production of propylene.Nevertheless,current PDH catalysts mainly rely on precious Pt or toxic Cr and especially undergo severe coke deposition.Herein,we report a Ru catalyst decorated by boron species(Ru-3B/Al_(2)O_(3)),which exhibits high catalytic performance for PDH.HAADF-STEM,EELS,and CO-FTIR characterization are used to identify the surface structure of the Ru active component,which shows that the high-energy unsaturated coordination sites,including corners,edges and step atoms for Ru-3B/Al_(2)O_(3),are appropriately modified by BO_(x)species.The encapsulation of high-energy active sites prone to Csingle bondC cracking and deep dehydrogenation leads to higher propylene selectivity(>95%)and strong carbon resistance(kd 0.0007 min)over Ru-3B/Al_(2)O_(3).The XPS and H2-TPR results show that the migration of B species is driven by the reduction of B_(2)O_(3)to B2O2 and that the coating degree of Ru particles is controlled by the chemical valance of Ru species.
文摘This review shows that relatively simple changes to diet and lifestyle can significantly,and rapidly,reduce the risks associated with coronavirus disease 2019(COVID-19)in terms of infection risk,severity of disease,and even disease-related mortality.A wide range of interventions including regular exercise,adequate sleep,plant-based diets,maintenance of healthy weight,dietary supplementation,and time in nature have each been shown to have beneficial effects for supporting more positive health outcomes with COVID-19,in addition to promoting better overall health.This paper brings together literature from these areas and presents the argument that non-pharmaceutical approaches should not be overlooked in our response to COVID-19.It is noted that,in several cases,interventions discussed result in risk reductions equivalent to,or even greater than,those associated with currently available vaccines.Where the balance of evidence suggests benefits,and the risk is minimal to none,it is suggested that communicating the power of individual actions to the public becomes morally imperative.Further,many lives could be saved,and many harms from the vaccine mandates avoided,if we were willing to embrace this lifestyle-centred approach in our efforts to deal with COVID-19.
