Hydrophobic activated carbon supported Ni-based acid-resistant catalyst for selective hydrogenation of phthalic anhydride to phthalide

• Ni supported on hydrophobilized AC is more acid-resistant than on original AC.
• Promoter Fe is beneficial to the stability of the Ni-based catalyst.
• The optimized Ni-based catalyst shows high hydrogenation activity and stability.

Activated carbon supported nickel-based catalysts doped with Fe were prepared by the incipient wetness impregnation method. In order to improve the acid-resistant stability of the catalyst, the nickel catalysts supported on hydrophobic activated carbon were also prepared by the same method. The as-prepared catalysts were applied for the liquid phase selective hydrogenation of phthalic anhydride to phthalide. The experimental results showed that Fe doped Ni/activated carbon catalyst containing 5 wt.% Fe and 15 wt.% Ni had the best catalytic performance among the nickel catalysts tested, with 100% of phthalic anhydride conversion and 95.2% of selectivity to phthalide at 180 °C and 4.0 MPa H2. When the activated carbon support was pretreated with NaBH4, the acid-resistant ability of the as-prepared Ni–Fe catalyst was remarkably enhanced, and the catalyst could be reused more than 8 times with slight decrease in activity, which was much better than the one without hydrophobization. The remarkable catalytic performance might be attributed to (1) the addition of Fe to form an alloy with Ni, dispersing the electron clouds around Ni atoms and stabilizing the Ni catalyst; (2) the application of hydrophobilized activated carbon as a support, preventing produced water from contacting the metal surface, which could reduce the corrosion of Ni as the activity of the H+ concentration decreases.