Exploration of the Role of Heat Activation in Enhancing Serpentine Carbon Sequestration Reactions

Abstract

As compared with other candidate carbon sequestration technologies, mineral carbonation offers the unique advantage of permanent disposal via geologically stable and environmentally benign carbonates. The primary challenge is the development of an economically viable process. Enhancing feedstock carbonation reactivity is key. Heat activation dramatically enhances aqueous serpentine carbonation reactivity. Although the present process is too expensive to implement, the materials characteristics and mechanisms that enhance carbonation are of keen interest for further reducing cost. Simultaneous thermogravimetric and differential thermal analysis (TGA/DTA) of the serpentine mineral lizardite was used to isolate a series of heat-activated materials as a function of residual hydroxide content at progressively higher temperatures. Their structure and composition are evaluated via TGA/DTA, X-ray powder diffraction (including phase analysis), and infrared analysis. The meta-serpentine materials that were observed to form ranged from those with longer range ordering, consistent with diffuse stage-2 like interlamellar order, to an amorphous component that preferentially forms at higher temperatures. The aqueous carbonation reaction process was investigated for representative materials via in situ synchrotron X-ray diffraction. Magnesite was observed to form directly at 15 MPa CO2 and at temperatures ranging from 100 to 125 degrees C. Carbonation reactivity is generally correlated with the extent of meta-serpentine formation and structural disorder.

CO2 Capture by Accelerated Carbonation of Alkaline Wastes: A Review on Its Principles and Applications

“…The majority of previous research has focused on the aqueous carbonation of naturally occurring silicate minerals such as serpentine (Mckelvy et al, 2004;Alexander et al, 2007;Krevor and Lackner, 2011), olivine (Haug et al, 2010), limestone (Symonds et al, 2009) and wollastonite (Tai et al, 2006;Huijgen et al, 2006c;Daval et al, 2009) due to their high calcium or magnesium content. Although the CO 2 storage capacity of these natural Ca-Mg-silicate minerals is sufficient to fix the CO 2 emitted from the combustion of fossil fuels, the technological carbonation of these minerals is slow and energy demanding.…”

“…Various studies have addressed methods to speed up the kinetics of direct aqueous carbonation including physical and chemical pretreatment (Maroto-Valer et al, 2005a, b), electrolysis and heat pretreatment , and mechanical activation methods (McKelvy et al, 2004;Park and Fan, 2004;Haug et al, 2010;Haug et al, 2011). O'Connor et al (2002) investigated approaches to reduce particle size, and increase surface area, and elevate process temperature and pressure by thermal treatment or steam activation.…”

“…The rate of carbonation reaction can be enhanced by adding acids or caustic alkali-metal hydroxide (Beard et al, 2004), utilizing a bicarbonate/salt (NaHCO 3 /NaCl) mixture (Maroto-Valer et al, 2005a;O'Connor et al, 2005), employing various pretreatment techniques (i.e., including physical and chemical pretreatment (Maroto-Valer et al, 2005a, b), electrolysis and heat pretreatment , mechanical activation methods (McKelvy et al, 2004;Park and Fan, 2004;Haug et al, 2010;Haug et al, 2011)), and using wastewater/brine as liquid agents (Chou, 2011;Liu and Maroto-Valer, 2011;Nyambura et al, 2011). However, pretreatments and addition of chemicals tend to consume additional energy and materials.…”

In situ high-temperature Raman and FTIR spectroscopy of the phase transformation of lizardite

“…The stable products of the dehydroxylation reaction of pure magnesian lizardite under hydrothermal conditions are talc, forsterite, and water (O'Hanley et al 1989). Various authors (e.g., McKelvy et al 2004;Brindley and Zussman 1957) reported low-angle peaks in X-ray diffractograms of thermally treated serpentine phases, indicating that amorphization is not complete and that dehydroxylation produces intermediate partially ordered structures. Although differing in detail, early studies by Ball and Taylor (1963) and Brindley and Hayami (1965) proposed reaction sequences with disordered dehydroxylated intermediates.…”

Mineral CO2 sequestration by environmental biotechnological processes

“…Elevated temperature and pressure using finely powdered silicate minerals accelerate carbonation reactions rates (Maroto-Valer et al, 2005;McKelvy et al, 2004), but the costs are high limiting industrial application. A large fraction of the estimated costs is associated with grinding of the silicate minerals to smaller particles (> 60 % of the total costs) (Gerdemann et al, 2007;Huijgen et al, 2007;Renforth et al, 2011).…”