Synthesis of dimethyldiphenylmethane over supported 12-tungstophosphoric acid (H3PW12O40)

SiO2, MCM-41 and activated carbon supported 12-tungstophosphoric acid (H3PW12O40, HPW) were used in the direct synthesis of dimethyldiphenylmethane (CH3C6H4CH2C6H4CH3, DMDPMs) from toluene and formaldehyde, and characterized by FT-IR, XRD and nitrogen adsorption. It was found that SiO2 supported HPW exhibited higher activity and DMDPMs selectivity, and the yield of DMDPMs increased with the loading amount of HPW. The best yield of DMDPMs reached 61.3% when the loading of HPW increased to 60 wt.% on SiO2. FT-IR and XRD analysis indicated that HPW dispersed highly on the surface of these supports. Highly dispersed HPW exhibited higher activity (higher TON) than that of pure HPW. While MCM-41 suffered severe structural distortions when the loading amount of HPW is high.

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