Benzene hydrogenation over oxide-modified MCM-41 supported ruthenium–lanthanum catalyst: The influence of zirconia crystal form and surface hydrophilicity

• Different crystal form ZrO2 modified MCM-41 were tested in benzene hydrogenation.
• Tetragonal ZrO2-MCM-41 with higher hydrophilicity increase cyclohexene selectivity.
• Monoclinic ZrO2-MCM-41 with more Brønsted acid sites reduce cyclohexene selectivity.
• ZrO2-MCM-41 with larger pore size and volume is better for cyclohexene selectivity.

The effects of the preparation conditions on the crystal form and surface properties of zirconia were studied. Mesoporous MCM-41 modified by tetragonal and monoclinic zirconia were synthesized by hydrothermal and precipitation methods. Then MCM-41 and zirconia-modified MCM-41 supported ruthenium–lanthanum catalysts were prepared via cyclohexane–water double solvent impregnation method. The obtained supports and catalysts were characterized by powder X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy, N2 adsorption–desorption, thermogravimetric and differential scanning calorimetry, temperature programmed desorption of NH3, static water/benzene adsorption techniques. It has been found that MCM-41 modified by tetragonal zirconia with exclusive Lewis-acidic sites exhibits more surface hydroxyl groups and higher hydrophilicity than MCM-41 modified by monoclinic and amorphous zirconia. Tetragonal zirconia-modified MCM-41 supported ruthenium–lanthanum catalyst shows better catalytic performance in benzene hydrogenation to cyclohexene with benzene conversion of 54.4% and cyclohexene selectivity of 84.7%.

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