Aqueous-phase biphasic dehydroaromatization of bio-derived limonene into p-cymene by soluble Pd nanocluster catalysts

A biphasic approach to the dehydroaromatization of bioderived limonene into water-insol. p-cymene using sol. Pd nanoparticle catalysts in an aq. phase (³150 °C, 2 bar H2) was successfully achieved with a conversion of 93% and a selectivity of 82%. The Pd nanoparticles, operating under forcing conditions (180 °C, 2 bar H2), can be recycled at least four times without noticeable degrdn. The effects of temp., pressure, reaction time, pH, catalyst concn., metal type, the type and amt. of polymer stabilizer, and the prepn. method were systematically investigated to optimize the process and provide insight into the mechanisms involved.