Carbonized cellulose microspheres loaded with Pd NPs as catalyst in p-nitrophenol reduction and Suzuki-Miyaura coupling reaction

Abstract

Catalytic reduction of p-nitrophenol is usually carried out using transition metal nanoparticles such as gold, palladium, silver and copper, especially palladium nanoparticles, which are characterized by fast reaction rate, high turnover frequency, good selectivity and high yield. However, the aggregation and precipitation of the metals lead to the decomposition of the catalyst, which results in a significant reduction of the catalytic activity. Therefore, the preparation of homogeneous stabilized palladium nanoparticle catalysts has been widely studied. Stabilized palladium nanoparticles mainly use synthetic polymers. Cellulose microspheres, as a natural polymer material with low cost and porous fiber network structure, are excellent carriers for stabilizing metal nanoparticles. Cellulose microspheres impregnated with palladium metal nanoparticles were carbonized to have a larger specific surface area and highly dispersed palladium nanoparticles, which exhibited excellent catalytic activity in the catalytic reduction of 4-nitrophenol. In this aspect, cellulose carbon-based microspheres Pd nanoparticles (Pd@CCM) catalysts were designed and characterized by SEM, TEM, EDS, XRD, FTIR, XPS, TGA, BET and so on. Furthermore, the catalytic performance of Pd@CCM catalysts were investigated via 4-nitrophenol reduction, which showed high catalytic activity. This catalyst also exhibited excellent catalytic performance in Suzuki-Miyaura coupling reaction. Linking aromatic monomer and benzene through Suzuki-Miyaura coupling was presented as an effective route to obtain polymeric substrate with low-cost and simple synthesis method. In addition, cellulose carbon-based microspheres Pd nanoparticles catalyst showed desirable recyclability with maintaining its catalytic activity even after five recycles. This work is highly suggestive on the heterogeneous catalysts design and application.