Active sites and reactive intermediates in the hydrogenolytic cleavage of C-C bonds in cyclohexane over supported iridium

► Structure sensitivity of cyclohexane ring opening (RO) is studied on Ir catalysts. ► The variation of TOF values presents a minimum at intermediate Ir dispersions. ► The TOF change on small particles is related to the fraction of low-CN atoms. ► Changed nature and size requirement of MARI cause TOF to increase on large particles. ► The relevant MARI is more H-depleted for the multiple hydrogenolysis than for RO.