Biochar provides an efficient strategy for making use of biomass residues, because it has shown to be a multifunctional material in energy and environmental applications. However, the underdeveloped porosity of biochar often makes it perform below potential. Herein, a novel activation method, namely simultaneous alkali/air activation, was tested for hierarchical pore development in biochar. The enhanced performance of the as-prepared porous carbon was evaluated by loading of palladium (Pd) for catalyzing formic acid dehydrogenation, a key reaction for the safe storage and transport of hydrogen. It was found that NaHCO3 was more effective than KOH on mesopore development in biochar when it was activated by air together. The carbon product possessing developed hierarchical pore structure (SABET = 1013 m2 g−1, SAmeso/SABET = 33.0 %) was obtained at 700 °C, using NaHCO3 as the alkali activator in a mixed air/nitrogen gas flow (30/70 by volume). The hierarchical pore structure of carbon made it a competent carrier of Pd catalyst, because the hierarchical pores not only enhanced the dispersion of Pd nanoparticles, but also served as the fast channels for the reactants to access the active sites intra catalyst particles. Therefore, the fast formic acid dehydrogenation (TOF = 156 h−1) was achieved when using the Pd catalyst loaded on such a hierarchically porous carbon.

中文翻译：

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碱/空气同步活化，用于生物炭中的多级孔开发，并用作甲酸脱氢的催化剂载体


生物炭为利用生物质残留物提供了一种有效的策略，因为它已被证明是一种多功能材料，可用于能源和环境应用。然而，生物炭的孔隙率不足通常使其性能低于潜力。在此，测试了一种新的活化方法，即同时碱/空气活化，用于生物炭中的分层孔隙发展。通过负载钯 （Pd） 来评估所制备的多孔碳的增强性能，以催化甲酸脱氢，这是安全储存和运输氢气的关键反应。研究发现，当 NaHCO3 一起被空气激活时，它比 KOH 对生物炭中的中孔发育更有效。在 700 °C 下，使用 NaHCO3 作为空气/氮气混合流中的碱活化剂（体积为 30/70）获得具有发达多级孔结构的碳产物 （SABET = 1013 m2 g-1，SAmeso/SABET = 33.0 %）。碳的多级孔结构使其成为 Pd 催化剂的合格载体，因为多级孔不仅增强了 Pd 纳米颗粒的分散性，而且还作为反应物进入催化剂内部活性位点的快速通道。因此，当使用负载在这种分层多孔碳上的 Pd 催化剂时，实现了快速甲酸脱氢 （TOF = 156 h-1）。