25th International Technical Conference on Coal Utilization and Fuel Systems, Clearwater, FL (US), 2000

Hamdallah Bearat's picture
Research Title: 
Mg(OH){sub 2} dehydroxylation: Implications for enhancing CO{sub 2} mineral sequestration reaction processes
Sharma, R.
Chizmeshya, A.V.G.
McKelvy, M.J.
Bearat, H.
Carpenter, R.W.
Mon, 2000-03-06
Research Abstract: 

Unlike many other proposed CO{sub 2} sequestration technologies, which provide long-term storage, mineral carbonation provides permanent disposal in the form of geologically stable mineral carbonates. Mineral carbonation avoids the ongoing problems and costs associated with long-term storage, such as guaranteeing permanent containment, avoiding adverse environmental consequences, and the ongoing cost of site monitoring. The primary goal for mineral sequestration is to develop cost competitive processes. Enhancing carbonation reaction rates is crucial to process costs. Mg-rich lamellar-hydroxide minerals provide an intriguing class of materials for enhancing carbonation reactivity, as the associated dehydroxylation process can disrupt the mineral structure at the atomic level. Mg(OH){sub 2} was chosen as a model system to study the relationship between Mg(OH){sub 2} dehydroxylation/rehydroxylation processes and carbonation reactivity. Recently, the authors discovered, via in situ atomic-level imaging, that Mg(OH){sub 2} dehydroxylation is best described as a lamellar nucleation and growth process, which can access, at least locally, a range of lamellar oxyhydroxide intermediate materials, Mg{sub x+y}O{sub x}(OH){sub 2y}, during dehydroxylation. These intermediates can provide a broad range of new carbonation reaction pathways. Controlled formation of such intermediates via dehydroxylation/rehydroxylation can substantially enhancing Mg-rich or Ca-rich lamellar-hydroxide-based mineral carbonation processes. These mechanisms offer excellent potential for enhancing carbonation reactivity and lowering mineral sequestration process costs via materials and process engineering.