Conversion of benzyl alcohol to benzonitrile over a Cu10.3/SiO2 catalyst

• Benzonitrile was synthesized via amination-dehydrogenation of benzyl alcohol over Cu/SiO2 catalysts.
• The catalyst Cu10.3/SiO2 showed best performance among all the catalysts.
• The doping of Cu created both Lewis acid sites and dehydrogenation active species in the matrix of SiO2.
• The deactivation reasons of the catalyst were disclosed.

A Cu10.3/SiO2 catalyst was prepared for the conversion of benzyl alcohol to benzonitrile through amination-dehydrogenation process. The catalyst showed high activity in the reaction, and a yield as high as 98.0% was reached under the optimized conditions. The catalyst was characterized by XRD, TEM-EDX, TG-DSC, N2 adsorption-desorption and IR of absorbed pyridine methods. The characterization results disclosed that the doping of copper created Lewis acid sites in the matrix of SiO2. The doped copper in the fresh catalyst was present in CuO state, which was reduced to elemental Cu by H2 generated in situ in the catalytic run. The characterization results also disclosed that the catalyst deactivation was mainly caused by the carbonaceous deposition on the surface of the catalyst in the catalytic reaction. The experimental results confirmed that most activity of the catalyst can be recovered at 550 °C online by blowing air into the reactor. Partial sintering of copper particles took place during the catalytic run, which led to the slight decreases of Lewis acidity and dehydrogenation capacity, therefore, caused deviation of the performance of the regenerated Cu10.3/SiO2 catalyst from that of the fresh one.

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