CaO-Based Nanomaterials Promoted with CaZrO3 for High-Temperature Carbon Capture

Abstract

Calcium looping is a promising route for decarbonization of carbon-intensive fossil fuel-reliant industries. Development of sorbents with high CO2 uptake capacity and cyclic stability is of paramount importance for commercialization of the calcium looping process. In this work, novel CaO-based sorbents stabilized with CaZrO3 were produced using the solution combustion synthesis method. The effect of using different fuels (citric acid and β-alanine) on the physical properties and the carbon capture performance of the sorbents was investigated. Citric acid-synthesized sorbents indicated a higher surface area (30.0 m2/g) compared to β-alanine-derived sorbents (9.3 m2/g), resulting in a superior CO2 uptake capacity. Sorbents were calcined under mild (850 °C, under 100% N2) and harsh (950 °C, under ∼50% CO2 in N2) calcination conditions in 20-cycle experiments. Under harsh calcination conditions, sorbents exhibited a decreased stability over cycles due to sintering and loss of surface area at high temperatures. The CA20-1x sorbent maintained 96 and 57% of its initial uptake capacity after 20 cycles under mild and harsh calcination conditions, respectively. Sorbents were further spheronized and tested for their uptake capacity and stability. Spheronized sorbents exhibited a reduced uptake capacity under similar testing conditions due to diffusion limitations and a broader uptake rate profile. A longer carbonation time was recommended for spheronized sorbents to improve the uptake capacity.