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.