Inexpensive and easily replicable precipitation of CuO nanoparticles for low temperature carbon monoxide and toluene catalytic oxidation

Hippolyte Todou Assaouka; Daniel Manhouli Daawe; Roussin Lontio Fomekong; Issah Njiawouo Nsangou; Patrick Mountapmbeme Kouotou

doi:10.1016/j.heliyon.2022.e10689

Inexpensive and easily replicable precipitation of CuO nanoparticles for low temperature carbon monoxide and toluene catalytic oxidation

Heliyon. 2022 Sep 19;8(9):e10689. doi: 10.1016/j.heliyon.2022.e10689. eCollection 2022 Sep.

Authors

Hippolyte Todou Assaouka¹, Daniel Manhouli Daawe², Roussin Lontio Fomekong³, Issah Njiawouo Nsangou¹, Patrick Mountapmbeme Kouotou^{2

4}

Affiliations

¹ Department of Chemistry, Faculty of Sciences, University of Maroua, P.O. Box.: 55, Maroua, Cameroon.
² National Advanced School of Engineering, University of Maroua, P.O. Box. 46, Maroua, Cameroon.
³ Higher Teacher Training College, University of Yaounde 1, P.O. Box 47, Yaoundé, Cameroon.
⁴ Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China.

Abstract

Herein CuO nanoparticles (NPs) with nanostructures were prepared by precipitation method using hydrate copper sulfate (CuSO₄.5H₂O) and sodium hydroxide followed by heat treatment at 400 °C. The as-prepared CuO NPs with nanostructures were investigated using X-ray diffraction (XRD), Fourier Transformed Infra-red spectroscopy (FTIR), Raman spectroscopy, Scanning electron microscopy (SEM), X-ray photochemical spectroscopy (XPS), Energy dispersive spectroscopy (EDS), and Ultra-violet-visible (UV-vis) spectroscopy. In order to evaluate the reducibility, temperature programmed reduction (H₂-TPR) was applied. More importantly, CuO NPs was successfully tested as catalyst towards the total conversion of carbon monoxide (CO) and toluene (C₇H₈). Both XRD and Raman analysis as well as FTIR show that the sample exhibited a monoclinic spinel structure. SEM images indicate that CuO NPs are well-covered by grains size exhibiting homogeneous morphology composed of very fine interconnected particles with an apparent porosity. The sample was made up of Cu and O, according to the XPS and EDS measurements. The band gap energy obtained from optical property analysis is ∼2.65 eV. The catalytic performances of CuO NPs can be assigned to the combined effects of crystal structure, morphology, surface oxygen mobility, redox property and the higher specific surface area (∼87 m²/g). More precisely XPS and H₂-TPR data suggests that, the conversion of CO and C₇H₈ over CuO NPs follows a Mars-van Krevelen type mechanism. More importantly CuO NPs catalysts is reusable and exhibited good stability in the prolonged isothermal test. Thus, CuO NPs is confirmed as an efficient and inexpensive catalysts for CO and C₇H₈ conversion at low temperatures.

Keywords: Carbon monoxide; Catalytic oxidation; Copper oxide; Precipitation; Toluene.