Abstract Hydrogen has a significant impact on the formation of vacancies, clusters and voids in palladium and other metals. The formation of vacancy-hydrogen complexes in bulk Pd and at Σ3 and Σ5 grain boundaries was investigated using first-principles calculations and thermodynamic models. Equilibrium vacancy and cluster concentrations were evaluated as a function of temperature and hydrogen partial pressure based on the Gibbs energy of formation including vibrational and configurational entropies. Vacancies were found to be significantly stabilized by association with interstitial hydrogen, leading to enhanced concentrations by several orders of magnitude. Vacancy clusters were further stabilized at grain boundaries, with equilibrium concentrations reaching site saturation for clusters comprising up to three vacancies. Nanovoids were investigated based on Wulff constructions from calculated surface energies of the (0 0 1) and (1 1 1) terminations as a function of temperature and coverage of hydrogen adsorbates. The most stable termination changed from (1 1 1) in vacuum to (0 0 1) in H2, and the surface energies were lowered due to hydrogen adsorbates. Consequently, voids were also stabilized in the presence of hydrogen. Coalescing of vacancies into nanovoids was found to be thermodynamically unfavorable due to the loss of configurational entropy. It was therefore concluded that enhanced concentrations of vacancies and clusters does not directly cause the formation of voids. The formation of voids in Pd-based membranes was discussed in terms of microstructural characteristics, and strain due to chemical expansion and plastic deformation.
{"title":"Hydrogen Induced Vacancy Clustering and Void Formation Mechanisms at Grain Boundaries in Palladium","authors":"J. M. Polfus, O. Løvvik, R. Bredesen, T. Peters","doi":"10.2139/ssrn.3606803","DOIUrl":"https://doi.org/10.2139/ssrn.3606803","url":null,"abstract":"Abstract Hydrogen has a significant impact on the formation of vacancies, clusters and voids in palladium and other metals. The formation of vacancy-hydrogen complexes in bulk Pd and at Σ3 and Σ5 grain boundaries was investigated using first-principles calculations and thermodynamic models. Equilibrium vacancy and cluster concentrations were evaluated as a function of temperature and hydrogen partial pressure based on the Gibbs energy of formation including vibrational and configurational entropies. Vacancies were found to be significantly stabilized by association with interstitial hydrogen, leading to enhanced concentrations by several orders of magnitude. Vacancy clusters were further stabilized at grain boundaries, with equilibrium concentrations reaching site saturation for clusters comprising up to three vacancies. Nanovoids were investigated based on Wulff constructions from calculated surface energies of the (0 0 1) and (1 1 1) terminations as a function of temperature and coverage of hydrogen adsorbates. The most stable termination changed from (1 1 1) in vacuum to (0 0 1) in H2, and the surface energies were lowered due to hydrogen adsorbates. Consequently, voids were also stabilized in the presence of hydrogen. Coalescing of vacancies into nanovoids was found to be thermodynamically unfavorable due to the loss of configurational entropy. It was therefore concluded that enhanced concentrations of vacancies and clusters does not directly cause the formation of voids. The formation of voids in Pd-based membranes was discussed in terms of microstructural characteristics, and strain due to chemical expansion and plastic deformation.","PeriodicalId":122205,"journal":{"name":"Alternative Transport Fuels eJournal","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126669156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This note shows that the egalitarian Dutta and Ray (1989) solution for transferable utility games is self-antidual on the class of exact partition games. By applying a careful antiduality analysis, we derive several new axiomatic characterizations. Moreover, we point out an error in earlier work on antiduality and repair and strengthen several related characterizations on the class of convex games.
{"title":"Antiduality in Exact Partition Games","authors":"Bas J. Dietzenbacher, E. Yanovskaya","doi":"10.2139/ssrn.3549335","DOIUrl":"https://doi.org/10.2139/ssrn.3549335","url":null,"abstract":"This note shows that the egalitarian Dutta and Ray (1989) solution for transferable utility games is self-antidual on the class of exact partition games. By applying a careful antiduality analysis, we derive several new axiomatic characterizations. Moreover, we point out an error in earlier work on antiduality and repair and strengthen several related characterizations on the class of convex games.","PeriodicalId":122205,"journal":{"name":"Alternative Transport Fuels eJournal","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131059932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Electric vehicles (EVs) have advanced significantly this decade, owing in part to decreasing battery costs. Yet EVs remain more costly than gasoline fueled vehicles over their useful life. This paper analyzes the additional advances that will be needed, if electric vehicles are to significantly penetrate the passenger vehicle fleet.
{"title":"Charging the Future: Challenges and Opportunities for Electric Vehicle Adoption","authors":"Henry Lee, A. Clark","doi":"10.2139/SSRN.3251551","DOIUrl":"https://doi.org/10.2139/SSRN.3251551","url":null,"abstract":"Electric vehicles (EVs) have advanced significantly this decade, owing in part to decreasing battery costs. Yet EVs remain more costly than gasoline fueled vehicles over their useful life. This paper analyzes the additional advances that will be needed, if electric vehicles are to significantly penetrate the passenger vehicle fleet.","PeriodicalId":122205,"journal":{"name":"Alternative Transport Fuels eJournal","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123701823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
biomass pyrolysis was investigated with the Fe-Mg-Co catalysts in a fixed bed reactor, with focus on the change of the yields of char, tar and gaseous products. The catalysts were prepared by impregnation method with different Fe, Mg, Co mass ratios. Among the catalysts, the 15 Fe 0.8 Mg 0.7 Co catalyst is the most efficient in upgrading the pyrolysis of biomass，and the syngas yield is 47.85 %. Experimental results showed that the yields of hydrogen and light aromatics could be greatly improved with Fe-Mg-Co catalysts. The maximum hydrogen yield of 113.48 ml/g is obtained with the 15 Fe 0.8 Mg catalyst at 700 ℃. Comparable trends were observed with increasing temperature, which had a positive effect on cracking reactions of tar. Additionally, Fe-Mg-Co not only promoted cracking and restructuring of tar but also enhanced the thermal decomposition of heavier tar at the higher temperature, which resulted in the improve of BTX (benzene, toluene, xylene), PCN ( phenol, cresol, naphthalene) yields. The best conditions for the formation of BTX, PC and naphthalene are 15 Fe 0.8 Mg 0.7 Co at 700 ℃.
{"title":"Co-Production of Aromatics and Hydrogen from Catalytic Pyrolysis of Biomass Using Fe-Mg-Co Bifunctional Catalysts","authors":"Yuan Shenfu, Liu Jianfeng, Lu Qiuxiang","doi":"10.2139/ssrn.3706648","DOIUrl":"https://doi.org/10.2139/ssrn.3706648","url":null,"abstract":"biomass pyrolysis was investigated with the Fe-Mg-Co catalysts in a fixed bed reactor, with focus on the change of the yields of char, tar and gaseous products. The catalysts were prepared by impregnation method with different Fe, Mg, Co mass ratios. Among the catalysts, the 15 Fe 0.8 Mg 0.7 Co catalyst is the most efficient in upgrading the pyrolysis of biomass，and the syngas yield is 47.85 %. Experimental results showed that the yields of hydrogen and light aromatics could be greatly improved with Fe-Mg-Co catalysts. The maximum hydrogen yield of 113.48 ml/g is obtained with the 15 Fe 0.8 Mg catalyst at 700 ℃. Comparable trends were observed with increasing temperature, which had a positive effect on cracking reactions of tar. Additionally, Fe-Mg-Co not only promoted cracking and restructuring of tar but also enhanced the thermal decomposition of heavier tar at the higher temperature, which resulted in the improve of BTX (benzene, toluene, xylene), PCN ( phenol, cresol, naphthalene) yields. The best conditions for the formation of BTX, PC and naphthalene are 15 Fe 0.8 Mg 0.7 Co at 700 ℃.","PeriodicalId":122205,"journal":{"name":"Alternative Transport Fuels eJournal","volume":"334 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121674747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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