The synthesis of multiphasic ionic liquid-coated Pt/Al2O3 catalysts: the selective synchronous hydrogenation of CC and CO bonds and the modeling of the ionic liquid and solvent effects

Abstract

Various ionic liquids (ILs) and their mixtures were coated on the Pt/Al₂O₃ catalyst and the resulting IL-coated catalysts were used in the synchronous hydrogenation of cyclohexene and acetone. The rate constant (k) and selectivity (S) toward CO hydrogenation were determined for several catalysts in various solvents. The solvatochromic parameters (E_T^N, normalized polarity parameter; π*, dipolarity–polarizability; β, hydrogen-bond acceptor basicity; α, hydrogen-bond donor acidity) were determined for the used ILs and solvents and the obtained selectivities were modeled based on the solvatochromic parameters of the IL layer and bulk solvent while using the Multiparameter Linear Regression (MLR) method for the first time. Selectivity toward the CO bond increases by increasing the percentage of 2-hydroxy ethylammonium formate (HEAF) in the IL layer and decreasing the polarity of the solvents. The single-parameter correlations of lnS versus π* presented the best correlation for the prepared catalysts in all solvents.