Total Oxidation of Propane Using CeO2 and CuO-CeO2 Catalysts Prepared Using Templates of Different Nature

Benjamin Solsona,Rut Sanchis,José López Nieto,Lidia Ruiz-Rodríguez,Tomas García,Enrique Rodríguez-Castellón,Ana Dejoz,Juan Cecilia

doi:10.3390/catal7040096

Abstract

Several CeO2 and CuO-CeO2 catalysts were prepared using different methods, i.e., a homogeneous precipitation with urea, a nanocasting route using CMK-3 carbon as a hard template and a sol–gel process using Poly(methyl methacrylate) (PMMA) polymer as a soft template, and tested in the total oxidation of propane. The catalysts were characterized by a number of physicochemical techniques (XRD, N2 adsorption, TPR, XPS, Raman spectroscopy) showing distinct characteristics. For each series, Cu-Ce-O catalysts with low Cu-loadings (5 wt % CuO) showed the highest activity, higher than those samples either without copper or with high Cu-loading (13 wt % CuO). The incorporation of copper leads to an increase of the concentration of bulk defects but if the Cu-loading is too high the surface area drastically falls. The highest activity in the total oxidation of propane was achieved by Cu-containing ceria catalysts synthesized using a polymer as a template, as this method yields high surface area materials. The surface area and the number of bulk/sub-surface defects of the ceria seem to be the main properties determining the catalytic activity.

Highlights

The release of volatile organic compounds (VOCs) into the atmosphere has been related to long term environmental impacts such as the formation of ground level ozone and ozone depletion, and they act as greenhouse gases [1,2]
We describe the preparation of ceria and CuO-CeO2 catalysts using different methods, with the objective of producing materials with optimal catalytic performances in the catalytic elimination of propane by total oxidation
It can be seen that catalysts prepared using the polymer present the highest surface area (154 m2 /g in the case of CuCe5-P) followed by those with the CMK-3 carbon and those prepared with urea

Summary

Introduction

The release of volatile organic compounds (VOCs) into the atmosphere has been related to long term environmental impacts such as the formation of ground level ozone and ozone depletion, and they act as greenhouse gases [1,2]. There are a number of methods for conversion of VOCs but one of the most efficient is the catalytic oxidation as low temperatures are required for elevated conversions [3]. VOCs are widely emitted by numerous different sources as they are a primary source of fuel, but not all VOCs affect the environment on the same scale because longer carbon chain. VOCs are much easier to remove than smaller VOCs such as short chain alkanes (methane, ethane and propane) [4,5]. Methane is the second most abundant greenhouse gas and has a global warming potential ca. Another common short chain alkane is propane, which, more reactive than methane, requires intermediate/high reaction temperatures to be activated. Propane is increasing in usage as a fuel in transport vehicles to a lesser extent

Methods

Results

Conclusion