Acidity and alkylation activity of 12-tungstophosphoric acid supported on ionic liquid-functionalized SBA-15

Abstract A series of heterogeneous catalysts with tunable superacidity, namely 12-tungstophosphoric acid (HPW) immobilized on imidazolium chloride ionic liquid (IL)-modified mesoporous SBA-15 silica (denoted as z- HPW-IL/SBA; z = HPW/IL molar ratio), were prepared. The physicochemical properties of these synthesized catalysts were characterized by various analytical and spectroscopic techniques such as EA, ICP-MS, XRD, FT-IR, N 2 adsorption/desorption isotherm measurements, and multinuclei NMR. In particular, their acid properties were characterized by solid-state 31 P NMR of adsorbed trimethylphosphine oxide (TMPO) as the probe molecule. The HPW-IL/SBA catalysts were exploited for catalytic alkylation of benzene with 1-dodecene, and relevant effects of their acid features ( i.e. , amount, strength, and distribution of acid sites) on catalytic performances and yields of linear alkylbenzenes (LABs) were investigated. It was found that the acidity of the z -HPW-IL/SBA catalyst may readily be controlled by varying the molar ratio ( z ) of the incorporated HPW-IL composite. Moreover, superior 1-dodecene conversion and LAB selectivity were simultaneously achieved with z  = 1.16, revealing an optimal preservation of superacidic Bronsted acid sites.