Synthesis of the cross-linked humic acid supporting palladium catalyst and its catalytic properties for Heck reaction

Cross-linked humic acid supporting palladium (CL-HA-Pd) catalyst was prepared readily and characterized by infrared analysis (IR) and thermogravimetric analysis (TG). The catalyst could catalyze the Heck reaction of aryl halide or substituted aryl halide with vinyl compounds in N₂ atmosphere; the yields were above 95%. The catalyst could be recovered and reused 7 times with the Heck reaction of iodobenzene with acrylic acid, and the yield was above 75.6%. The results showed that the catalyst had high catalytic activity even at low temperature of 62°C or with a small amount of the catalyst.