摘要
传统甾醇中间体氧化采用重金属铬作为氧化剂,存在毒性大和环境污染等问题。电催化氧化(ECO)以其高效、环保、可控的优点备受青睐,被认为是一种可替代传统工艺的方法。然而,目前ECO面临低电流密度和低时空产率的挑战。本研究采用一步溶剂热法在石墨毡上制备自支撑NiFe-MOF纳米片电催化剂,并耦合NiFe-MOF与氮氧自由基(4-乙酰氨-2,2,6,6-四甲基哌啶-1-氧)协同电催化策略以提高ECO性能。研究发现碱性电解液可重构NiFe-MOF催化剂,从而提高催化活性。此外,连续流动强化传质,成功实现以100 mA·cm^(-2)的大电流密度对19-羟基-4-雄甾烯-3,17-二酮(1a)的选择性电催化氧化,且选择性高达98%,时空产率可达15.88 kg·m^(-3)·h^(-1),是间歇电反应器的35倍。寿命测试发现经10次循环反应后,NiFe-MOF/ACT协同体系对ECO仍具有较高的转化率。通过增大NiFe-MOF面积,将其组装至连续流动式电反应器并进行ECO恒电流电解,可达到12.99 kg·m^(-3)·h^(-1)的时空产率。该工作提出一种NiFe-MOF/ACT协同电催化氧化策略,为实现甾醇选择性氧化提供新的见解。
Conventional oxidation methods of sterol intermediates using the heavy metal chromium as an oxidant has critical drawbacks,such as high toxicity and environmental pollution.Electrocatalytic oxidation(ECO),on the other hand,is considered a promising alternative to conventional processes owing to its high efficiency,eco-friendliness,and controllability.However,ECO currently faces two major challenges:low current densities and reduced space-time yields.In this study,a single-step solvothermal method was employed to synthesize self-supported nickel-iron metal-organic framework(NiFe-MOF)nanosheet electrocatalysts on graphite felt.Various analytical techniques were employed to comprehensively characterize the synthesized NiFe-MOF,including scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),Raman spectroscopy,and Brunauer-Emmett-Teller(BET)analysis Furthermore,we implemented a synergistic electrocatalytic strategy by combining the NiFe-MOF catalyst with aminoxyl radicals,i.e.,4-acetamido-2,2,6,6-tetramethyl-1-piperidine-N-oxyl(ACT),to enhance the performance of the ECO reaction.According to the results of structural characterization,the synthesized NiFe-MOF exhibited an amorphous nanosheet structure with a high specific surface area and microporosity.Moreover,we successfully achieved continuous flow with enhanced mass transfer during the electrocatalytic oxidation of 19-hydroxy-4-androstene-3,17-dione(1a)at a current density of 100 mA·cm^(-2).The optimal reaction conditions for the ECO reaction were as follows:100 mmol·L^(-1)concentration of 1a,10%(molar fraction)of ACT,a 1 mol·L^(-1)Na_(2)CO_(3)/acetonitrile electrolyte(6:4),room temperature,pH 12.5,and a flow rate of 225 mL·min-1.Under these conditions,the conversion and selectivity of the reaction reached outstanding levels of 99 and 98%,respectively.Moreover,the space-time yield was calculated to be as high as 15.88 kg·m^(-3)·h^(-1),with a remarkable 35-fold increase compared to that achieved in a batch reactor.The NiFe-MOF/ACT synergistic system demonstrated a high conversion rate for ECO even after 10 reaction cycles.To assess the system’s efficacy in converting other sterols,we conducted an analysis of substrate expansion,which yielded conversion rates exceeding 95%.The SEM,TEM,and XPS results of the catalyst obtained before and after the reaction indicated that the alkaline electrolyte could effectively reconstitute the NiFe-MOF structure,leading to a significant improvement in its performance.By leveraging a ten-fold increased surface area of the NiFe-MOF and constructing a continuous flow electroreactor for ECO with a constant current,we achieved a remarkable space-time yield of 12.99 kg·m^(-3)·h^(-1).Thus,we developed a synergistic electrocatalytic oxidation strategy based on NiFe-MOF/ACT,and this study not only provides valuable insights for realizing the selective oxidation of sterols but also contributes to the advancement of sustainable and efficient chemical processes.
作者
许银洁
李随勤
刘力豪
贺佳辉
李凯
王梦欣
赵舒影
李纯
张峥斌
钟兴
王建国
Yinjie Xu;Suiqin Li;Lihao Liu;Jiahui He;Kai Li;Mengxin Wang;Shuying Zhao;Chun Li;Zhengbin Zhang;Xing Zhong;Jianguo Wang(Institute of Industrial Catalysis,State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology,College of Chemical Engineering,Zhejiang University of Technology,Hangzhou 310032,China;Research and Development Department,Zhejiang Xianju Junye Pharmaceutical Co.,Ltd.,Taizhou 317300,Zhejiang Province,China)
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2024年第3期44-45,共2页
Acta Physico-Chimica Sinica
基金
国家重点研发计划(2022YFA1504200,2021YFA1500903)
浙江省自然科学基金(LR22B060003)
国家自然科学基金(22078293,21625604,91934302,22141001)资助项目。
关键词
甾醇
电催化氧化
金属有机框架
氮氧自由基
协同作用
Sterol
Electrocatalytic oxidation
Metal-organic frameworks
Aminoxyl radical
Synergistic effect
