【摘 要】
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The purpose of this work was to determine whether the presence of inorganic species(Na,K,Mg,Ca)will affect the behavior of lignite dehydration by theoretical study.The structures of lignite model comp
【机 构】
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School of Chemical Engineering & Technology,China University of Mining and Technology,Xuzhou 221008,
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The purpose of this work was to determine whether the presence of inorganic species(Na,K,Mg,Ca)will affect the behavior of lignite dehydration by theoretical study.The structures of lignite model compounds were investigated by B3LYP,PW91,and M06-2X functional.And the coordination of metal cations(M= Na+,K+,Mg2+,Ca2+)and water molecules(W)on the gas phase structural stability of lignite Lig-M(W)n=1-5 were carried out at the same level of theory.The M06-2X was more suitable than the B3LYP and PW91 toward the intermolecular hydrogen bonding.In complexes,Lig-M where M= K+ and Na+ coordinated to C=O modes of lignite were more stable.However,in case of Lig-Mg2+ and Ca2+,the structure where coordinated to-OH mode was found to be more stable.Stepwise addition of water molecules changed the stability of Lig-M(W)n species.And we found that binding energies was not significant increased by increasing the number of water,likely because the intermolecular hydrogen bonds become significant.The effect of dehydration on lignite with Mg2+ and Ca2+ were larger than Na+ and K+.
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