N,O‐Codoped Onion‐like Carbon Catalyzed Selective Oxidation of Methanol to Dimethoxymethane: Structure‐Activity Relationship

Abstract One‐step synthesis of dimethoxymethane (DMM) via methanol oxidation under the catalysis of nanocarbon is a green and sustainable chemical industrial process. In this work, nitrogen, oxygen codoped onion‐like carbon (NOLC) were prepared via a simple thermal treatment method, which was applied to one‐step synthesis of DMM. The physicochemical characterization results revealed that nitrogen and oxygen elements were successfully introduced into the onion‐like carbon (OLC) catalyst. The proposed NOLC catalysts exhibited DMM selectivity of 75 % at relatively low reaction temperature (150 °C) and long stability over 10 h. In‐situ titration experiments revealed that the carboxylic acid groups on NOLC surface were the main acidic active sites. The Clemmensen reduction control experiment revealed that the carbonyl groups were the active sites for the formation of formaldehyde. The basic reaction kinetics and mechanism such as reaction orders, apparent activation energy and rate determining step etc. for one‐step synthesis of DMM via methanol were studied systematically. The present work shows an important structure‐function relation for designing highly efficient nanocarbon catalyzed methanol conversion reaction system that the appropriate redox/acid intensity on catalyst surface through the modulation of N and O elements would effectively improve the selectivity of DMM.