Conversion of ethanol to 1,3-butadiene over Na doped ZnxZryOz mixed metal oxides

• Mixed ZnxZryOz oxide catalysts achieved comparable 1,3-butadiene selectivities as best catalysts for ethanol to 1,3-butadiene.
• A combination of Zn/Zr ratio and Na addition is efficient to control the acidity and basicity, and eventually selectivity to 1,3-butadiene.
• Brønsted acid sites likely play a role in acetaldehyde to 1,3-butadiene conversion.
• 2000 ppm Na doped Zn1Zr10Oz exhibits slow deactivation and good regeneration properties.

Despite numerous studies on different oxide catalysts for the ethanol to 1,3-butadiene reaction, few have identified active sites (i.e., type of acidity) correlated to the catalytic performances. In this work, the type of acidity needed for ethanol to 1,3-butadiene conversion has been studied over Zn/Zr mixed oxide catalysts. Specifically, synthesis method, Zn/Zr ratio, and Na doping have been used to control the surface acid–base properties, as confirmed by characterizations such as NH3-TPD and IR-Py techniques. The 2000 ppm Na doped Zn1Zr10Oz-H with balanced base and weak Brønsted acid sites was found to give not only high selectivity to 1,3-butadiene (47%) at near complete ethanol conversion (97%), but also exhibited a much higher 1,3-butadiene productivity than other mixed oxides studied.

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