Descriptors for High-Performance Nitrogen-Doped Carbon\nCatalysts in Acetylene Hydrochlorination

Abstract

Nitrogen-doped carbons\nare promising materials for a broad range\nof applications. However, their rational design is greatly hampered\nby the lack of efficient methods to control the nitrogen speciation,\nwhich not only causes controversy about the roles of specific nitrogen\nfunctionalities but also hinders investigations into other physicochemical\ncharacteristics of these materials. We herein present a cutting-edge\nstrategy that allows a systematic tuning of the electrical conductivity\nof polyaniline-derived N-doped carbons at a defined nitrogen speciation\nand content, and similar porous properties. By application of these\nmodel systems in acetylene hydrochlorination, a major industrial technology\nfor the production of polyvinyl chloride, we provide insights into\nthe active sites and the reaction mechanism and disclose two key catalytic\ndescriptors for N-doped carbons in this reaction: (i) a high content\nof pyrrolic-N functionalities, promoting the adsorption of the reactants,\nand (ii) good electrical conductivity, likely influencing the surface\ndiffusion of adsorbed species. Since increasing the electrical conductivity\nleads to a reduced nitrogen content, the interplay between these two\nproperties must be carefully controlled to maximize catalytic performance.\nThis understanding enabled the design of the first N-doped carbon\ncatalyst that rivals the unprecedented activity of benchmark gold-based\nsystems in acetylene hydrochlorination.