Zirconia incorporated calcium looping absorbents with superior sintering resistance for carbon dioxide capture from in situ or ex situ processes

Abstract

The sintering deactivation of Ca-based absorbents has greatly limited the application of calcium looping for either in situ or ex situ processes. In this work, a series of CaO sorbents stabilized with CaZrO₃ were prepared by three different wet chemistry methods: freeze drying, spray drying and heating drying. Multi-cycle CO₂ capture tests under relatively mild conditions demonstrated that the spray-dried sorbents performed best. Based on both total CO₂ uptake and the deactivation rate, the optimum content of CaZrO₃ was 20 wt%. Under severe conditions, the best sorbent could even retain a capacity of 0.47 g and 0.44 g CO₂ per g sorbent at cycle 30 and cycle 100, respectively, which showed notable superiority over previously reported similar materials. The stabilization mechanism was explored by characterization. It was found that the introduction of CaZrO₃ increased the specific surface area and the spray drying method generated a spherical structure, which could retain some pores after severe tests. Three semi-empirical equations were introduced to describe the evolution of the decay process.