Screening CaO-Based Sorbents for CO 2 Capture in Biomass Gasifiers

Abstract

Coupling biomass gasification with in situ CO 2 capture significantly enhances the yield of hydrogen. For this process, CaO is the most likely CO 2 sorbent. However, the development of a sorbent that is resistant to physical deterioration and maintains reactivity through multiple cycles is a limiting step in the scale-up and commercial operation of a continuous process. To this end, we describe an experimental protocol for screening CO 2 sorbents and then use this to assess the performance of six targeted CaO-based sorbents: CaO derived from commercially available CaCO 3 ( d p = 25.8 µm), commercially available Ca(OH) 2 ( d p = 9.2 µm), precipitated CaCO 3 ( d p = 3.2 µm), CaCO 3 nanoparticles ( d p = 509.4 nm), and presintered CaO doped with Li 2CO 3 and with K 2CO 3. The protocol allows the measurement of reactivity through multiple CO 2 capture-and-release cycles; this is a significant step in determining the overall consumption of sorbent and, hence, the cost of one of the key parts of the process.