Influence of Pd NPs size for bio-adipic acid production from muconic acid and sodium muconate

Among the several subjects, the production of bulk chemicals from renewable sources is one of the great challenges that researchers are facing. Concerning this theme, adipic acid (AdA) production from wood biomass is one of the most important topics due to the large amount of AdA consumed and the market growth, in particular to produce polyamides (Nylon 6,6). Bio-AdA can be produced from t,t-muconic acid (t,t-MA), a metabolic intermediate of the catechol ortho-cleavage pathway.[1] Sodium muconate (Na-Muc) produced from bacteria can be converted to AdA with a heterogeneous hydrogenation chemical reaction.[2] 1% Pd/AC catalysts are well known for their high activity in hydrogenation reaction. Different catalysts were synthesized using sol-immobilization method[3], which allow to obtain small Pd NPs with controlled shape and size. The amount of stabilizer (polyvinyl alcohol) was varied to obtain catalyst with different Pd NPs size. Catalysts where characterized by BET, TEM and XPS analyses. All the catalysts show higher activity than 5% Pd/AC commercial catalyst and Na-Muc hydrogenation is more influenced by Pd NPs size, Pd(0)/Pd(II) ratio than t,t-MA hydrogenation.