Selective hydrogenation of 1,3-butadiene on iridium nanostructures: Structure sensitivity, host effect, and deactivation mechanism

A systematic study on the structure sensitivity, host effect, and the deactivation mechanism of Ir-catalyzed selective hydrogenation of 1,3-butadiene, a key process in the purification of alkadiene for the upgrading of C4 cut, is presented by coupling steady-state catalytic testing, in-depth characterization, kinetic evaluation, and density functional theory calculations. We reveal that: (i) 1,3-Butadiene hydrogenation on iridium is structure-sensitive with the optimal particle size of about 2 nm, and the H-2 dissociation energy is a reliable activity descriptor; (ii) The nature of the NC hosts exerts a critical impact on the catalytic performance, and balanced nitrogen content and speciation seem key for the optimized performance; and (iii) Different deactivation mechanisms occur: fouling by coke deposition on the catalysts with a high N:C ratio (>1), and site blockage due to the competitive adsorption between 1-butene/cis-2-butene and 1,3-butadiene. These molecular insights provide valuable guidelines for the catalyst design in selective hydrogenations. (C) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.