M-Mn-Al hydrotalcite-like compounds as precursors for methyl benzoate hydrogenation catalysts

Mn-Al and M-Mn-Al (M = Mg, Zn, Ni, Pb, Cr) hydrotalcite-like compounds (HTlcs) were synthesized by a coprecipitation method. The hydrogenation of methyl benzoate to benzaldehyde over the calcined HTlcs was investigated. Mn2Al1 catalyst calcined in N-2 gives a better performance than a conventional 10% Mn/gamma-Al2O3 catalyst. Incorporation of Mg2+, Zn2+, Pb2+, and Cr3+ into the Mn-Al hydrotalcite-like precursor may further enhance the catalytic activity of the calcined catalysts. The conversion of methyl benzoate and selectivity to benzaldehyde on Pb0.2Mn1.8Al1 catalyst at 370 degreesC are 94.4 and 84.9%, respectively. X-ray diffraction, temperature-programmed reduction, and CO2 temperature-programmed desorption studies show that the redox and basic properties of the catalysts play an important role in the reaction.