Long-term activity of a CuO/SBA-15 type SOx adsorbent: Impact of the regeneration step

Abstract

Sulphur oxides (SOx) are a major air pollutant regulated by European legislations. To date, most efficient DeSOx technologies are energy-intensive and produce high amounts of waste. Thus CuO/SiO2 adsorbents represent a viable SOx trapping alternative. However, their large-scale development is hampered by the sintering of the active phase over multiple adsorption and regeneration cycles, leading to the progressive decrease in performance of the adsorbent. In this work, a CuO/SBA-15 adsorbent was assessed as a SOx trap material and different regenerations methods were evaluated with the aim to limit that sintering phenomenon and assure the conservation of SO2 adsorption performance over several adsorption and regeneration cycles. It was found that a regenerative treatment under 0.5 vol% of H2 in N2 can be carried out either at 300 °C or 400 °C, without any substantial loss of SO2 adsorption performance over 8 successive cycles. A diffusional-limited decomposition mechanism describes the different steps of the regeneration stage, especially the kinetics of the regeneration step that is governed by the H2 transport within the porosity. The SO2 adsorption process was not the main degradation path of the textural properties of the adsorbent but the latter are strongly affected by the thermal effect associated to the adsorption and regeneration cycling.