Experimental and modeling study of isobutane alkylation with C4 olefin catalyzed by Brønsted acidic ionic liquid/sulfuric acid

•The introduction of SFILs can contribute to a higher selectivity of C8 as well as the RON.•Enrichment of alkyl chains on cations can be found at interface.•The addition of SFILs is favorable to larger interface width, and better dispersion of C4 hydrocarbons at interface.•Simulated values of interfacial properties agree well with alkylation experiments.