The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these c...The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these catalysts were buried in the carbon matrix,resulting in a low metal utilization and inaccessibility for adsorption of reactants during the catalytic process.Herein,we reported a facile synthesis based on the hard-soft acid-base(HSAB)theory to fabricate Co single-atom catalysts with highly exposed metal atoms ligated to the external pyridinic-N sites of a nitrogen-doped carbon support.Benefiting from the highly accessible Co active sites,the prepared Co−N−C SAC exhibited a superior oxygen reduction reactivity comparable to that of the commercial Pt/C catalyst,showing a high turnover frequency(TOF)of 0.93 e^(−)·s^(-1)·site^(-1)at 0.85 V vs.RHE,far exceeding those of some representative SACs with a ultra-high metal content.This work provides a rational strategy to design and prepare M−N−C single-atom catalysts featured with high site-accessibility and site-density.展开更多
采用Aspen Plus V14建立了固定床煤气化炉的稳态流程模型,对脱矿胜利褐煤(SL^(+))及其加氢氧化钠样品(SL^(+)-NaOH)水蒸气气化过程进行模拟研究.依据实验数据对所建模型进行了准确性验证,证明该模型预测的合成气收率与实验值吻合较好....采用Aspen Plus V14建立了固定床煤气化炉的稳态流程模型,对脱矿胜利褐煤(SL^(+))及其加氢氧化钠样品(SL^(+)-NaOH)水蒸气气化过程进行模拟研究.依据实验数据对所建模型进行了准确性验证,证明该模型预测的合成气收率与实验值吻合较好.基于该模型,研究了汽煤比和气化温度对合成气组成和有效气(CO+H_(2))收率的影响.结果表明,SL^(+)气化合成气中有效气摩尔分数随汽煤比的增大先增大后减小,在汽煤比为0.74时达到最大值75.7%.气化温度对两种煤样的有效气组成影响较大.SL^(+)-NaOH中H2和CO_(2)的产量明显增加,而CO产量相较于SL+明显减少.展开更多
基金supported by Shanxi Province Science Foundation for Youths(202203021212300)Taiyuan University of Science and Technology Scientific Research Initial Funding(20212064)Outstanding Doctoral Award Fund in Shanxi Province(20222060).
文摘The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these catalysts were buried in the carbon matrix,resulting in a low metal utilization and inaccessibility for adsorption of reactants during the catalytic process.Herein,we reported a facile synthesis based on the hard-soft acid-base(HSAB)theory to fabricate Co single-atom catalysts with highly exposed metal atoms ligated to the external pyridinic-N sites of a nitrogen-doped carbon support.Benefiting from the highly accessible Co active sites,the prepared Co−N−C SAC exhibited a superior oxygen reduction reactivity comparable to that of the commercial Pt/C catalyst,showing a high turnover frequency(TOF)of 0.93 e^(−)·s^(-1)·site^(-1)at 0.85 V vs.RHE,far exceeding those of some representative SACs with a ultra-high metal content.This work provides a rational strategy to design and prepare M−N−C single-atom catalysts featured with high site-accessibility and site-density.
文摘采用Aspen Plus V14建立了固定床煤气化炉的稳态流程模型,对脱矿胜利褐煤(SL^(+))及其加氢氧化钠样品(SL^(+)-NaOH)水蒸气气化过程进行模拟研究.依据实验数据对所建模型进行了准确性验证,证明该模型预测的合成气收率与实验值吻合较好.基于该模型,研究了汽煤比和气化温度对合成气组成和有效气(CO+H_(2))收率的影响.结果表明,SL^(+)气化合成气中有效气摩尔分数随汽煤比的增大先增大后减小,在汽煤比为0.74时达到最大值75.7%.气化温度对两种煤样的有效气组成影响较大.SL^(+)-NaOH中H2和CO_(2)的产量明显增加,而CO产量相较于SL+明显减少.
