Kinetics of the Reaction of Ca(OH)₂ with CO₂ at Low Temperature

Abstract

The kinetics of the reaction of Ca(OH)2 with CO2 in humid N2 has been studied at 60−90 °C by using a differential reactor. Ca(OH)2 reacted with CO2 to form CaCO3 only when the relative humidity exceeded 0.08. The reaction ceased before 1 h, and Ca(OH)2 was incompletely converted. The reaction rate and final conversion of Ca(OH)2 were significantly affected by relative humidity, were slightly dependent on temperature, and were zeroth order with respect to gas phase CO2 concentration. The carbonation of Ca(OH)2 was well described by the asymptotic equation which is obtained by assuming chemical reaction control and considering the surface coverage by product. The rate-controlling step might be the dissolution of Ca(OH)2 at the water-adsorbed surface. The reaction behavior of Ca(OH)2 with CO2 was similar to that with SO2. The model derived for the reaction with CO2 may be applied to that with SO2 with proper modifications. The results of this study are useful to the design and efficient operation of the processes using hydrated lime to remove SO2 from the flue gas, in which both SO2 and CO2 are present.

Effect of water on carbonation of mineral aerosol surface models of kaolinite: a density functional theory study

“…From a thermodynamic point of view, it can be deduced that this reaction is quite difficult to take place without any other exogenic action at room temperature and under standard pressure. Although the corresponding experimental data are not available, it is similar to the experimental and theoretical results obtained in the waterfree carbonation of portlandite (Shih et al 1999;Nikulshina et al 2007). All stable structures and corresponding enthalpy changes are shown in Fig.…”

“…Many reactions of carbon dioxide with mineral surfaces and metal oxides have been studied both experimentally and theoretically to obtain information of carbon dioxide adsorption and carbonation (Tai et al 2004;Baltrusaitis et al 2006Baltrusaitis et al , 2007Wang et al 2007;Pan et al 2008;Allen et al 2009;Pulido et al 2009;Hornebecq et al 2011;Kwon et al 2011;Sorescu et al 2012;Wu et al 2012;Ye et al 2012;Funk et al 2013;Hur et al 2013). It is well known that the presence of water could significantly lower the reaction barriers and stabilize the reaction product (Shih et al 1999;Nikulshina et al 2007;Baltrusaitis and Grassian 2010;Kvamme et al 2012;Fricker and Park 2013;Gao et al 2013;Yu and Balbuena 2013;Wang and Cao 2013). However, the quantitative information on the gas/aerosol equilibrium and reaction of CO 2 on the surface of natural kaolinite, including the action of water in this carbonation process is generally not available.…”

Experimental and model investigation on the mass balance of a dry circulating fluidized bed for flue gas desulfurization system

“…There are many desulfurization models for hydrated sorbent, such as surface coverage model [27,28], non-ideal surface adsorption model [29], shrinking core model, grain model [30] and so on. A special desulfurization model for rapidly hydrated sorbent in CFB proposed by Li [31] is used in this investigation.…”

A realistic approach to modeling an in-duct desulfurization process based on an experimental pilot plant study

“…Also, they were able to define four regions with different prevailing reaction mechanisms, indicating that, in the end, the reaction rate drops significantly possibly because of pore closure. For Shih et al [10] the surface coverage model was found to be the most suitable model to describe the reaction between Ca(OH) 2 and CO 2 . Ho et al [11] extended this conclusion to explain the reaction of Ca(OH) 2 sulfation.…”

“…Furthermore, in this paper, different kinetic models have been adapted to the actual conditions of an in-duct desulfurization process, and the disagreement between predictions from these models and the experimental results obtained in a pilot plant, which are also published (i.e., [1,3]), is shown. Thus, a general kinetic model similar to the approaches of [9] and [10] has been adapted by minimizing the difference between the calculated and the experimental results from the pilot plant, using Matlab TM . The calculated values were obtained by simulation based on an in-duct desulfurization model together with a kinetic model.…”