Steam Catalysis in Calcinations of Dolomite and Limestone Fines

Maclntire, W. H.; Stansel, T. B.

doi:10.1021/ie50523a050

Cited by 50 publications

(28 citation statements)

References 6 publications

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“…In a previous publication (Heller-Kallai et al, 1986) we reported that addition of water to calcite in the pyroprobe caused evolution of a small but reproducible amount of CO2 (4.5 mg CO2/g calcite) below 250~ In agreement with other investigators (e.g. MacIntire & Stansel, 1953;Burnham et al, 1980;Paulik et al, 1980) we concluded that the presence of water reduced the temperature at which decomposition of calcite occurred. The experiment was repeated in the present study, but this time the slight acidity of the deionized water added was neutralized to pH 7.…”

Section: Transport Of Calcitesupporting

confidence: 89%

Volatile products of clay mineral pyrolysis revealed by their effect on calcite

Heller-Kallai¹,

Miloslavski

Aizenshtat

1987

Clay miner.

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The volatiles produced when various clay minerals were pyrolysed under a stream of He or in vacuo were condensed and analysed. They contain a wide range of cations and anions in concentrations ranging from ppm to hundreds ofppm. The reactivity of these volatiles was demonstrated by their reaction with calcite. It is suggested that the water liberated on heating acts as a scavenger of various impurities present in the clay.In a recent publication we reported that calcite 'dissolved' in the volatiles produced on heating clay minerals without any direct contact between the clay and the calcite (HellerKallai et al., 1986). When the gases evolved on pyrolysis of clays were passed through calcite heated in an apparatus of the Rock Eval type (Espitali6 et aI., 1977) some of the calcite was transported out of the pyroprobe into the analytical part of the system, where decomposition occurred, liberating CO2. No CaO or Ca(OH)2 remained in the pyroprobe. Calcite is very sparingly soluble in water and, although no data are available on the solubility in water vapour at temperatures up to 600~ it seems improbable that the observed effects are due to dissolution in pure water vapour. In the present study the 'dissolution' of calcite has been examined in greater detail and the volatiles derived from the clays are characterized.

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Section: Transport Of Calcitesupporting

confidence: 89%

Volatile products of clay mineral pyrolysis revealed by their effect on calcite

Heller-Kallai¹,

Miloslavski

Aizenshtat

1987

Clay miner.

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“…Although there is not a consensus in terms of the effect of steam on the carbonation reaction, previous work (Donat et al, 2012) has shown that the presence of steam in the atmosphere during cycles of carbonation and calcination improves the capture capacity of particles of CaO-based sorbents. It has also been shown that the presence of steam during calcination is beneficial to this process: one hypothesis is the increased rate of sintering of CaO upon steam addition, (Borgwardt, 1989) increases the rate of calcination (Maclntire and Stansel, 1953) and if carefully controlled, assists the formation of pores in the size ranges most conducive to long-term carbonation, previously described as ~ 50 nm diameter Alvares, 2003, Alvarez andAbanades, 2005) and thereby improves the carrying capacity of the sorbent. Donat et al,(Donat et al, 2012) showed that steam, when the steam concentration was varied from 0-20%, just 0.1% steam was sufficient to increase the final extent of carbonation -the extent of which depended on the type of limestone used -and that the carrying capacity of Longcliffe limestone did not increase significantly when the amount of steam added was increased above 1%.…”

Section: Introductionmentioning

confidence: 99%

Additive effects of steam addition and HBr doping for CaO-based sorbents for CO 2 capture

González

Blamey

Al-Jeboori

et al. 2016

Chemical Engineering and Processing: Process Intensification

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Calcium looping is a developing CO2 Capture and Storage technology that employs the reversible carbonation of CaO (potentially derived from natural limestone). The CO2 uptake potential of CaO particles reduces upon repeated reaction, largely through loss of reactive surface area and densification of particles. Doping of particles has previously been found to reduce the rate of decay of CO2 uptake, as has the introduction of steam into calcination and carbonation stages of the reaction. Here, the synergistic effects of steam and doping, using an HBr solution, of 5 natural limestones have been investigated. The enhancement to the CO2 uptake was found to be additive, with CO2 uptake after 13 cycles found to be up to 3 times higher for HBr-doped limestones subjected to cycles of carbonation and calcination in the presence of 10% steam, in comparison to natural limestone cycled in the absence of steam. A qualitative discussion of kinetic data is also presented.

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“…It has been shown that the thermal decomposition of CaCO 3 is accelerated by water vapor. [19][20][21][22] Wang and Thomson 21 described that adsorbed water vapor weakened Ca-CO 3 bond and the thermal decomposition of CaCO 3 was accelerated by water vapor. Furthermore, the lower CO 2 partial pressure in water vapor atmosphere might enhance the decomposition of CaCO 3 .…”

Section: Formation Of Catiomentioning

confidence: 99%