Development of oxygen carriers for chemical looping combustion: effects of support microstructure on the performance of oxygen carriers

摘要

CO2 capture drives considerable R&D inputs into the advancement of chemical looping combustion (CLC) process, which is a promising and efficient technology to generate pure CO2 exhaust from fossil fuel powered plants. In the CLC process, oxygen storage material or oxygen carriers, composed of active metal oxides and supports, play critical roles by transferring combustion needed oxygen from air reactor to combustion reactor. To develop high performance oxygen carriers, the choice of supports as well as the effect of its microstructural characteristics is well worth to be studied. In this work, by taking CuO as active metal oxide and silica as supporting material, we investigated the relationship between the performance of CuO oxygen carrier and the microstructural characteristics of silica supports. The main messages of this work can be classified into: 1) with our recently developed 'CIP-filtration' method, the porous microstructure of silica supports was able to be tuned and a series of silica granules with varied pore volume, open porosity as well as pore size distributions were fabricated; 2) via the employment of dry impregnation method, CuO was loaded onto the silica granules and the loading amount shows a linear relationship with the open porosity of supports. A high loading amount of 50 wt% was already achieved with a only 2-cycle impregnation procedure, which is much more efficient than literature work; 3) the oxygen transport capacity of fabricated CuO oxygen carrier shows a strong reliance on the loading amount of CuO, while the conversion rate of CuO increases with the increase of supports open porosity, and the reaction rates of CuO oxygen carrier was assumed to be related with the pore size variation caused size difference of CuO units. (C) 2016 Elsevier Inc. All rights reserved,