Salt-template hydrothermal carbonization for Pd NP-loaded porous carbonaceous material

Inorganic salt is a promising stabilizer in the hydrothermal synthesis of porous carbon materials. A three-dimensional palladium-loaded (Pd-loaded) lignin carbonaceous material with a porous structure was developed via hydrothermal carbonization, with lignin as not only a carbon source but also a reducing and stabilizing agent for palladium nanoparticles (Pd NPs) and then with LiCl as the hard template and porogen. The porogen-induced Pd-loaded carbonaceous material displayed an orderly pore structure with more porosity than the porogen-free Pd-loaded carbonaceous material. Subsequently, the porogen-induced Pd-loaded carbonaceous materials were transferred to an aqueous phase filter and mixed with reactants in a syringe as catalysts. The catalyst exhibited excellent catalytic performances in the reduction reaction of 4-nitrophenol to 4-aminophenol by NaBH4, with a rate constant of 0.11 min-1, which was higher than that of the porogen-free Pd-loaded carbonaceous material. In this study, LiCl was employed as the hard template and porogen to construct the porous carbonaceous structure and improve the porosity by stabilizing the pore structure and minimizing collapse, which provided a new way to synthesize lignin porous carbonaceous material.