While some of the microscopic, (sub)surface-related parameters of the S SISSO C4 model of Eq. 7 also appear in the S SISSO C2H4 model of Eq. 6, the bulk parameters and s BET only appear in the expression for the selectivity towards C 4 . This indicates that, in addition to surface processes, bulk phenomena related to the properties of the NP volume and the distance between NPs could impact the formation of C 4 molecules, and likely that of the oligomers.