Thermal Activation of Antigorite for Mineralization of CO₂

Abstract

This contribution demonstrates the sensitivity of antigorite dehydroxylation to treatment conditions and discusses the implications of the observations for scientific (i.e., dehydroxylation kinetics) and technological (i.e., energy efficient conditions and design of practical activation reactors) applications. At present, the energy cost of dehydroxylation of serpentinite ores represent the most important impediment for a large scale implementation of sequestering CO(2) by mineralization. We have analyzed changes in antigorite's derivative thermogravimetric curves (DTG) and deduced factors affecting the mass loss profiles. The imposed heating rate, type of purge gas, type of comminution and sample mass all influence the dehydroxylation curve. However, the results show no influence of material of construction of the heating vessel and flow rate of the purge gas. We report an important effect of oxidation of Fe(2+) under air purge gas that occurs prior to dehydroxylation and leads to formation of hematite skins on serpentinite particles, slowing down subsequent mass transfer and increasing the treatment temperature. From the process perspective, 75 μm particles afford optimal conditions of temperature and rate of dehydroxylation. Overall, the practical considerations, in thermally activating serpentinite ores for storing CO(2) by carbonation, comprise rapid heating, proper size reduction, prior demagnetisation, and fluidization of the powder bed.

Dehydroxylation of serpentine minerals: Implications for mineral carbonation

“…23 Although thermal activation improves the extent of serpentines conversion to carbonates, this process requires substantial energy input and may not guarantee high degree of carbonation. 16,17,21,22,[24][25][26] After the preliminary section describing the serpentine minerals, this review provides the necessary background on the dehydroxylation of serpentine minerals and discusses associated concepts of particular significance to mineral carbonation. It evaluates published studies of these minerals to identify the treatment conditions and types of dehydroxylated mineral phases formed that increase the reactivity of treated serpentines for their reaction with CO 2 .…”

Serpentinite Carbonation for CO2 Sequestration

“…The release of Mg from silicate minerals is likely a rate-limiting step in mineral carbonation. Serpentine carbonation is slow relative to olivine carbonation but can be enhanced (Balucan and Dlugogorski 2013). However, serpentinite continues to be a focus for mineral carbonation because of the accessibility of large deposits to serve as feedstock.…”

Recent advances in the photocatalytic reduction of carbon dioxide

“…However, since C in the CO 2 exhibits the highest oxidation state, the CO 2 itself is chemically stable, and the standard Gibbs free energy (DG h ) of CO 2 is -394.39 kJ mol -1 (Dean 1998), which means CO 2 is a kind of inert molecule and is difficult for activation. To react with other molecules, the kinetics inertia and thermodynamics energy barrier should be overcome, which generally requires employing high temperature (Balucan and Dlugogorski 2012), high pressure (Liu et al 2013c) and using catalysts (Drees et al 2012;Ashley and O'Hare 2013), including coordinating activation (Huff et al 2012;Vogt et al 2012), Lewis acidbase synergistic activation (Ashley et al 2009;Mömming et al 2009), photoelectric activation (Jing et al 2013), biological enzyme catalytic activation (Kumar et al 2010) and plasma activation (Li et al 2006), etc.…”