A new green technology of producing chromic anhydride with an electrochemical synthesis method was studied to solve the pollution problems in the traditional production process of chromic anhydride.The anolyte used wa...A new green technology of producing chromic anhydride with an electrochemical synthesis method was studied to solve the pollution problems in the traditional production process of chromic anhydride.The anolyte used was sodium dichromate solution, and the anode used was a self-made combination electrode of titanium matrix with a multiple-unit metal oxides active coating.The electrochemical behavior of sodium dichromate solution on a combination electrode of titanium matrix was studied with cyclic voltammetry as a part of the fundamental researches of this technique.The electrooxidation reaction of 160 cycles indicated that the electrode possessed a very stable electrochemical behavior.The peak currents ip and peak potentials Ep of the oxidation peaks for sodium dichromate solution of different concentrations, i.e., water under the existence of sodium dichromate, were experimentally measured at different temperatures and sweep rates v on the electrode.The equations of peak current ip versus v1/2 and peak potential Ep versus lnv were established, indicating that the electrode reaction was an irreversible diffusion-controlled reaction.The kinetic parameters and activation energy of electrode reaction was calculated, and the effects of temperature on the kinetic parameters and activation energy were preliminarily discussed.展开更多
利用可再生能源实现物质和能量的转化,是发展节能减排技术、实现双碳目标的重要手段.有机电合成是一种温和、清洁、高效的物质合成方法,可以有效解决传统化工过程的高能耗和高污染问题.将电解水制氢与有机电合成耦合,利用水分解产生的...利用可再生能源实现物质和能量的转化,是发展节能减排技术、实现双碳目标的重要手段.有机电合成是一种温和、清洁、高效的物质合成方法,可以有效解决传统化工过程的高能耗和高污染问题.将电解水制氢与有机电合成耦合,利用水分解产生的活性氧/氢直接氧化/还原有机物,不仅有助于降低能耗,还可以生产高附加值有机化工产品,是提高电能利用效率、降低生产成本的有效方案.然而,尽管这种方法具有诸多优势,其工业化应用仍面临一系列难题.本文回顾了电化学合成的发展历史,探讨了氢能时代为电化学合成带来的发展机遇.同时,分析了将电化学合成与电解水耦合所面临的挑战以及未来发展方向.首先,应当慎重选择与电解水制氢耦合的阳极反应体系,其氧化产物不但要具有比反应物更高的经济价值,而且要有较大的市场需求量,以匹配制氢规模.其次,虽然在热力学上有机物氧化比析氧更容易发生,但在动力学及传质方面,有机物氧化可能存在劣势,因此必须开发适用于工业制氢电流密度(500‒2000 mA cm^(‒2))的有机物氧化电极材料.第三,阳极有机产物选择性不仅影响反应物的利用率,而且决定后续分离纯化成本,需要通过调控活性氢/氧及有机物表面的竞争吸附等手段,提高阳极目标产物选择性及法拉第效率.第四,隔膜是分离两极反应物料、防止副反应发生的重要部件.然而,现有的阴、氧离子交换膜的耐有机物腐蚀性能差,需要开发适用于电解耦合体系的、具有高离子传导能力且性能稳定的新型隔膜材料.最后,当有机物氧化与电解水耦合后,产物的分离复杂程度增加,需要将精馏、萃取、膜分离等手段与电化学反应相结合,以提升电解过程效率.综上,本文讨论了电化学合成耦合可再生能源制氢的若干技术难题,为未来电合成与氢能技术共同发展提供新思路.展开更多
文摘A new green technology of producing chromic anhydride with an electrochemical synthesis method was studied to solve the pollution problems in the traditional production process of chromic anhydride.The anolyte used was sodium dichromate solution, and the anode used was a self-made combination electrode of titanium matrix with a multiple-unit metal oxides active coating.The electrochemical behavior of sodium dichromate solution on a combination electrode of titanium matrix was studied with cyclic voltammetry as a part of the fundamental researches of this technique.The electrooxidation reaction of 160 cycles indicated that the electrode possessed a very stable electrochemical behavior.The peak currents ip and peak potentials Ep of the oxidation peaks for sodium dichromate solution of different concentrations, i.e., water under the existence of sodium dichromate, were experimentally measured at different temperatures and sweep rates v on the electrode.The equations of peak current ip versus v1/2 and peak potential Ep versus lnv were established, indicating that the electrode reaction was an irreversible diffusion-controlled reaction.The kinetic parameters and activation energy of electrode reaction was calculated, and the effects of temperature on the kinetic parameters and activation energy were preliminarily discussed.
文摘利用可再生能源实现物质和能量的转化,是发展节能减排技术、实现双碳目标的重要手段.有机电合成是一种温和、清洁、高效的物质合成方法,可以有效解决传统化工过程的高能耗和高污染问题.将电解水制氢与有机电合成耦合,利用水分解产生的活性氧/氢直接氧化/还原有机物,不仅有助于降低能耗,还可以生产高附加值有机化工产品,是提高电能利用效率、降低生产成本的有效方案.然而,尽管这种方法具有诸多优势,其工业化应用仍面临一系列难题.本文回顾了电化学合成的发展历史,探讨了氢能时代为电化学合成带来的发展机遇.同时,分析了将电化学合成与电解水耦合所面临的挑战以及未来发展方向.首先,应当慎重选择与电解水制氢耦合的阳极反应体系,其氧化产物不但要具有比反应物更高的经济价值,而且要有较大的市场需求量,以匹配制氢规模.其次,虽然在热力学上有机物氧化比析氧更容易发生,但在动力学及传质方面,有机物氧化可能存在劣势,因此必须开发适用于工业制氢电流密度(500‒2000 mA cm^(‒2))的有机物氧化电极材料.第三,阳极有机产物选择性不仅影响反应物的利用率,而且决定后续分离纯化成本,需要通过调控活性氢/氧及有机物表面的竞争吸附等手段,提高阳极目标产物选择性及法拉第效率.第四,隔膜是分离两极反应物料、防止副反应发生的重要部件.然而,现有的阴、氧离子交换膜的耐有机物腐蚀性能差,需要开发适用于电解耦合体系的、具有高离子传导能力且性能稳定的新型隔膜材料.最后,当有机物氧化与电解水耦合后,产物的分离复杂程度增加,需要将精馏、萃取、膜分离等手段与电化学反应相结合,以提升电解过程效率.综上,本文讨论了电化学合成耦合可再生能源制氢的若干技术难题,为未来电合成与氢能技术共同发展提供新思路.
基金financial supports from Singapore Ministry of Education Academic Research Fund Tier 2(Grant No.MOE-T2EP10220-0005)Academic Research Fund Tier 1(Grant No.RG104/18)。
