Modulating the copper oxide morphology and accessibility by using micro-/mesoporous SBA-15 structures as host support: Effect on the activity for the CWPO of phenol reaction

Abstract

This study presents an original approach to the improvement of advanced oxidation process (AOP) efficiencies through the design of highly active catalysts. Then, removal of phenol was obtained under mild conditions by catalytic wet peroxide oxidation (CWPO) process over silica supported micropore and/or mesopore confined copper oxide nanoparticles. The materials, i.e. y wt.% CuO (y ranging from 4 to 10) on SBA-15 exhibiting different pore structure properties, were entirely characterized. In this study, we took advantage from the evolution of the micropore fraction in the mesoporous silica with the autoclaving temperature of synthesis. While only mesopore nanocasted copper oxide nanoparticle formed when the support exhibits only mesoporosity, micropore silica confined nanoparticles other formed the two supports exhibiting both micropores and mesopores. In this case, mesopore nanocasted nanoparticles can be only observed when copper oxide loading reaches 10wt.%. As a consequence, the copper active surface is suggested to be higher when copper incorporates interconnected micropores, without limited pore plugging issued from mesopore confined nanoparticle formation.For the phenol removal reaction, all the materials are exhibiting interesting activity, with a complete conversion of phenol and almost 60–80% of mineralization obtained in less than 2h at 60°C. Nevertheless, the results showed that the increase in copper loading up to high values is not needed to achieve high mineralization degree, due to the typical morphology of the materials, i.e. confinement of nanoparticles inside micropores or mesopores. In addition, the prepared materials allow a continuous use in reaction with leaching of active phase (≤4.4mgL−1) which also results in no water post-purification for cation removal as in the case of the classical homogeneous Fenton process.