Structure sensitivity of hydrogenolytic cleavage of endocyclic and exocyclic C-C bonds in methylcyclohexane over supported iridium particles

► Rates of endocyclic C-C cleavage feature a minimum at medium Ir dispersion. ► TOFs of demethylation monotonously increase with increasing Ir particle size. ► Ring opening (RO) selectivity decreases by up to three times with declining dispersion. ► Endocyclic and exocyclic cleavage proceed via different surface intermediates. ► DFT calculations show unfavored adsorption/dehydrogenation energetics at hindered C-C.