Microreactor with copper oxide nanostructured films for catalytic gas phase oxidations

Abstract

Three simple gas phase based methods were applied to copper foils with parallel microchannels to induce in-situ growth of nanostructured CuOx films. One method consisted in treating with vapors of NH4OH and H2O2 (VAP); another method consisted in heating in air at 500 °C (CAL); and the third one was a sequence of both methods (CAL-VAP). The synthesized CuOx films/Cu foils were assembled as microreactors and tested for CO oxidation, showing high catalytic performance and stability in reaction. The physicochemical characteristics of the films were examined by Scanning Electron Microscopy (SEM), Temperature-Programmed Reduction (TPR), X-ray Diffraction (XRD), Laser Raman Spectroscopy (LRS), Reflectance Infrared Fourier Transformed Spectroscopy (DRIFTS) and ultrasound tests. The VAP films consisted of thick clustered nanorods containing Cu+ and Cu2 + species in the outer layer of the coating. The CAL films presented uniform growth of nanoneedles in which the outer layers were composed mainly of Cu2 +. However, by submitting the CAL sample to the VAP procedure (CAL-VAP), part of CuO was reduced to Cu4O3 species. The developed microreactors with copper oxide nanostructures directly grown on microchannels with high thermal conductivity represent a low-cost, simple alternative for application in catalytic gas-phase reactions.