Effect of Cu substitution on promoted benzene oxidation over porous CuCo-based catalysts derived from layered double hydroxide with resistance of water vapor

• Porous CuCo-based catalysts deriving from CuxCo3−xAl-LDH precursors.
• Cu0.5Co2.5Al-MMO shows the maximum benzene oxidation activity and resistance of water vapor.
• Higher surface area, low-temperature reducibility and rich lattice oxygen.
• A monolithic CuCoAl-MMO film catalyst.

Porous and dispersed CuCo-based mixed metal oxides catalysts (denoted as CuxCo3−xAl-MMO) are obtained via the calcination of ternary CuxCo3−xAl-layered double hydroxide (LDH) precursors, which exhibit excellent catalytic activity towards complete oxidation of benzene. The Cu0.5Co2.5Al-MMO sample shows the maximum activity of 2.41 mmol gcat−1 h−1 with 90% benzene conversion at 290 °C at a high space velocity (SV = 60,000 mL g−1 h−1), comparable to that of only 8% conversion for Cu3Al-MMO sample. The significantly enhanced activity is correlated with higher surface area, narrower pore size, low-temperature reducibility and rich oxygen vacancies and lattice oxygen derived from the synergistic effect over porous and dispersive CuxCo3−xAl-MMO catalysts containing CuO and Co3O4 spinel mixed oxides verified by XRD, BET, H2-TPR, TEM and XPS measurements. Stability with prolonged time on benzene stream and the resistance to water vapor are further investigated. In addition, a monolithic CuCoAl-MMO film catalyst is fabricated by an in situ growth-calcination method, which displays comparable catalytic activity with CuxCo3−xAl-MMO powder. Therefore, this work provides a facile method for the preparation of CuCo-based catalysts with excellent characters responsible for better catalytic activities, which can be used as promising candidates for practical VOCs oxidation.

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