Recyclable Magnetic Fe3O4 Nanoparticle-Supported Chloroaluminate Ionic Liquids for Heterogeneous Lewis Acid Catalysis

In our efforts to overcome the limitations in using ionic liquids (ILs) as homogeneous catalysts, we prepared a heterogeneous analog by loading 10–40 wt% [HN222][Al2Cl7] ([HN222]+ = triethylammonium) onto Fe3O4 nanoparticles (NPs) to obtain free-flowing solid catalysts. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), and Brunauer–Emmett–Teller (BET) surface area analysis of 20% [HN222][Al2Cl7]/Fe3O4, all confirmed loading of the IL. Catalytic performance was assessed with the alkylation of benzene with benzyl chloride reaction, and 20% [HN222][Al2Cl7]/Fe3O4 was found to be the best catalyst with 100% conversion and 77% product selectivity. The catalyst was also found to be active for alkylation of other substrates such as toluene and o-, m-, and p-xylene. Utilizing a magnet for separation, the catalyst could be recycled and reused for five runs without loss of catalytic activity.