Defect‐rich BN‐supported Cu with superior dispersion for ethanol conversion to aldehyde and hydrogen

Copper‐based heterogeneous catalysts commonly exhibit uncontrolled growth of copper species under reaction conditions because of the low Hüttig temperature(surface mobility of atoms)and Tamman temperature(bulk mobility)for copper at just 134 and 405°C,respectively.Herein,we report the use of defect‐enriched hexagonal boron nitride nanosheets(BNSs)as a support to anchor the Cu species,which resulted in superior dispersion of the Cu species.The obtained Cu/BNS catalyst was highly stable for ethanol dehydrogenation,with a high selectivity of 98%for producing acetaldehyde and an exceptionally high acetaldehyde productivity of 7.33 g_(AcH) g_(cat)^(‒1) h^(‒1) under a weight hourly space velocity of 9.6 g_(EtOH) g_(cat)^(‒1) h^(‒1).The overall performance of our designed catalyst far exceeded that of most reported heterogeneous catalysts in terms of the stability of the Cu species and the yield of acetaldehyde in this reaction.The hydroxyl groups at the defect edges of BNS were responsible for the stabilization of the copper species,and the metal‐support interaction was reinforced through charge transfer,as evidenced by coupling atomic resolution images with probe molecule infrared spectroscopy and X‐ray photoelectron spectroscopy.A designed in situ diffuse reflectance infrared Fourier transform spectroscopy study of ethanol/acetaldehyde adsorption further revealed that Cu/BNS favored ethanol adsorption while suppressing acetaldehyde adsorption and further side reactions.This study demonstrates a new method for designing highly dispersed Cu‐based catalysts with high durability.

2种二芳醚农药中间体的合成

[目的]二芳醚是重要的农药中间体,用于合成多种重要的杀虫剂,如一些拟除虫菊酯、杀菌剂如醚唑等农药。3,4'-二氯二苯醚和3-甲基二苯醚分别是醚唑和戊菊酯的关键中间体,传统上采用铜粉为催化剂合成效率和选择性欠佳,为此,对2种二芳醚中间体合成进行优化和改进。[方法]采用商用铜粉和自制高分散铜为催化剂,分别对溶剂、反应摩尔比、反应温度、反应时间进行优化合成2种二芳醚中间体。[结果]3,4'-二氯二苯醚的选择性达86.7%,收率为82.2%;3-甲基二苯醚的收率为96.8%。[结论]实验结果显示高分散铜的催化活性和选择性都好于传统Ullmann反应催化剂。