title: Spray-Dried Sodium Zirconate: A Rapid Absorption Powder for CO2Capture with Enhanced Cyclic Stability.
abstract: Improved powders for capturing CO2at high temperatures are required for H2production using sorption-enhanced steam reforming. Here, we examine the relationship between particle structure and carbonation rate for two types of Na2ZrO3powders. Hollow spray-dried microgranules with a wall thickness of 100-300 nm corresponding to the dimensions of the primary acetate-derived particles gave about 75 wt % theoretical CO2conversion after a process-relevant 5 min exposure to 15 vol % CO2. A conventional powder prepared by solid-state reaction carbonated more slowly, achieving only 50 % conversion owing to a greater proportion of the reaction requiring bulk diffusion through the densely agglomerated particles. The hollow granular structure of the spray-dried powder was retained postcarbonation but chemical segregation resulted in islands of an amorphous Na-rich phase (Na2CO3) within a crystalline ZrO2particle matrix. Despite this phase separation, the reverse reaction to re-form Na2ZrO3could be achieved by heating each powder to 900 °C in N2(no dwell time). This resulted in a very stable multicycle performance in 40 cycle tests using thermogravimetric analysis for both powders. Kinetic analysis of thermogravimetric data showed the carbonation process fits an Avrami-Erofeyev 2 D nucleation and nuclei growth model, consistent with microstructural evidence of a surface-driven transformation. Thus, we demonstrate that spray drying is a viable processing route to enhance the carbon capture performance of Na2ZrO3powder.
authors.affiliation: School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, United Kingdom.
authors.forename: Faith
authors.initials: F
authors.lastname: Bamiduro
authors.affiliation: School of Environment, Tsinghua University, Beijing, 100084, P. R. China.
authors.forename: Guozhao
authors.initials: G
authors.lastname: Ji
authors.affiliation: School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, United Kingdom.
authors.forename: Andy P
authors.initials: AP
authors.lastname: Brown
authors.affiliation: School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, United Kingdom.
authors.forename: Valerie A
authors.initials: VA
authors.lastname: Dupont
authors.affiliation: School of Environment, Tsinghua University, Beijing, 100084, P. R. China.
authors.forename: Ming
authors.identifier: 0000-0002-5801-5593
authors.initials: M
authors.lastname: Zhao
authors.affiliation: School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, United Kingdom.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Milne
mesh_terms: D065966:Absorption, Physicochemical; D002245:Carbon Dioxide / Q000737:chemistry*; D003890:Desiccation; D010316:Particle Size; D011208:Powders / Q000737:chemistry; D012964:Sodium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D011208:Powders; C091751:sodium zirconate; D002245:Carbon Dioxide; D012964:Sodium; D015040:Zirconium
keywords: absorption; co2 capture; kinetic analysis; sodium zirconate; spray drying