Abstract: NH2C3H6-modified MCM-41 was synthesized by co-condensation of tetraethylorthosilicate (TEOS) and organosilane aminopropyltrimethoxysilane (APTES) at room temperature, and it was then used as the support to prepare the Pd/NH2C3H6-MCM-41 catalyst. The characterization by X-ray diffraction, NMR, FT-IR, transmission electron microscopy, X-ray photoelectron spectroscopy, and N2 adsorption revealed that both NH2C3H6-MCM-41 and Pd/NH2C3H6-MCM-41 remained mesoporous structure similar to that of MCM-41, but their degree of structrural order decreased with the increase in the amounts of the NH2C3H6[KG-47x]-[KG-15x][KG*2] group and Pd. During the Ullmann reaction of PhI performed in an aqueous medium, Pd/NH2C3H6-MCM-41 exhibited higher activity and higher selectivity for biphenyl than Pd/SiO2 and Pd/MCM-41. This may be due to the high and homogeneous dispersion of Pd particles, electron enrichment of metallic Pd, well-ordered mesoporous structure, suitable base strength, and hydrophobicity. The yield of biphenyl could reach 63%, showing good potential of the catalyst in industrial application.

Key words: palladium, supported catalyst, modification, MCM-41 zeolite, Ullmann reaction, iodobenzene, biphenyl