The geologic production of abiotic organic compounds has been the subject of increasing scientific attention due to their use in the global carbon flux balance,by chemosynthetic biological communities,and for energy r...The geologic production of abiotic organic compounds has been the subject of increasing scientific attention due to their use in the global carbon flux balance,by chemosynthetic biological communities,and for energy resources.Extensive analysis of methane(CH_(4))and other organics in diverse geologic settings,combined with thermodynamic modelings and laboratory simulations,have yielded insights into the distribution of specific abiotic organic molecules on Earth and the favorable conditions and pathways under which they form.This updated and comprehensive review summarizes published results of petrological,thermodynamic,and experimental investigations of possible pathways for the formation of particular species of abiotic simple hydrocarbon molecules such as CH_(4),and of complex hydrocarbon systems,e.g.,long-chain hydrocarbons and even solid carbonaceous matters,in various geologic processes,distinguished into three classes:(1)pre-to early planetary processes;(2)mantle and magmatic processes;and(3)the gas/water-rock reaction processes in low-pressure ultramafic rock and high-pressure subduction zone systems.We not only emphasize how organics are abiotically synthesized but also explore the role or changes of organics in evolutionary geological environments after synthesis,such as phase transitions or organic-mineral interactions.Correspondingly,there is an urgent need to explore the diversity of abiotic organic compounds prevailing on Earth.展开更多
Designing metal compounds based on their structure and chemical composition is essential in achieving desirable performance in methane oxidation,because of the synergistic effect between different metal elements.Herei...Designing metal compounds based on their structure and chemical composition is essential in achieving desirable performance in methane oxidation,because of the synergistic effect between different metal elements.Herein,a bimetallic Ru-Pt catalyst on TiO_(2) support(RuPt-O/TiO_(2)) was prepared by in situ reduction followed by calcination in air.Compared with monometallic catalysts(Ru-O/TiO_(2) and Pt-O/TiO_(2)),the synergistic effect of mixed metals endowed bimetallic catalysts with excellent stability and outstanding performance in methane oxidation,with a reaction rate of 13.9×10^(-5)mol^(-1)_(CH_(4))·g^(-1)_(Ru+Pt)·s^(-1)at 303℃.The varied characterization results revealed that among the bimetallic catalysts,RuO_(2)was epitaxially grown on the TiO_(2) substrate owing to lattice matching between them,and part of the PtO_(x) adhered to the RuO_(2) surface,in addition to a single PtO_(x) nanoparticle with 4 nm in size.Consequently,Pt mainly existed in the form of Pt2+and Pt4+and a small amount of zero valence in the bimetallic catalyst,prompting the adsorption and activation of methane as the first and rate-controlling step for CH_(4) oxidation.More importantly,the RuO_(2) species provided additional oxygen species to facilitate the redox cycle of the PtO_(x) species.This study opens a new route for structurally designing promising catalysts for CH4oxidation.展开更多
基金financially supported by the National Key Research and Development Program of China(Grant No.2019YFA0708501)the NSFC Major Research Plan on West-Pacific Earth System Multispheric Interactions(Grant No.92158206)。
文摘The geologic production of abiotic organic compounds has been the subject of increasing scientific attention due to their use in the global carbon flux balance,by chemosynthetic biological communities,and for energy resources.Extensive analysis of methane(CH_(4))and other organics in diverse geologic settings,combined with thermodynamic modelings and laboratory simulations,have yielded insights into the distribution of specific abiotic organic molecules on Earth and the favorable conditions and pathways under which they form.This updated and comprehensive review summarizes published results of petrological,thermodynamic,and experimental investigations of possible pathways for the formation of particular species of abiotic simple hydrocarbon molecules such as CH_(4),and of complex hydrocarbon systems,e.g.,long-chain hydrocarbons and even solid carbonaceous matters,in various geologic processes,distinguished into three classes:(1)pre-to early planetary processes;(2)mantle and magmatic processes;and(3)the gas/water-rock reaction processes in low-pressure ultramafic rock and high-pressure subduction zone systems.We not only emphasize how organics are abiotically synthesized but also explore the role or changes of organics in evolutionary geological environments after synthesis,such as phase transitions or organic-mineral interactions.Correspondingly,there is an urgent need to explore the diversity of abiotic organic compounds prevailing on Earth.
基金financially supported by National Natural Science Foundation of China(Nos.21922602,22076047 and U21A20326)Shanghai Science and Technology Innovation Action Plan(No.20dz1204200)the Fundamental Research Funds for the Central Universities。
文摘Designing metal compounds based on their structure and chemical composition is essential in achieving desirable performance in methane oxidation,because of the synergistic effect between different metal elements.Herein,a bimetallic Ru-Pt catalyst on TiO_(2) support(RuPt-O/TiO_(2)) was prepared by in situ reduction followed by calcination in air.Compared with monometallic catalysts(Ru-O/TiO_(2) and Pt-O/TiO_(2)),the synergistic effect of mixed metals endowed bimetallic catalysts with excellent stability and outstanding performance in methane oxidation,with a reaction rate of 13.9×10^(-5)mol^(-1)_(CH_(4))·g^(-1)_(Ru+Pt)·s^(-1)at 303℃.The varied characterization results revealed that among the bimetallic catalysts,RuO_(2)was epitaxially grown on the TiO_(2) substrate owing to lattice matching between them,and part of the PtO_(x) adhered to the RuO_(2) surface,in addition to a single PtO_(x) nanoparticle with 4 nm in size.Consequently,Pt mainly existed in the form of Pt2+and Pt4+and a small amount of zero valence in the bimetallic catalyst,prompting the adsorption and activation of methane as the first and rate-controlling step for CH_(4) oxidation.More importantly,the RuO_(2) species provided additional oxygen species to facilitate the redox cycle of the PtO_(x) species.This study opens a new route for structurally designing promising catalysts for CH4oxidation.
