Thermodynamics and kinetics of the reaction: CaCO/sub 3/ = CaO + CO/sub 2/
Hot-pressing experiments with CaCO/sub 3/ and CaO suggested that CO/sub 2/ promotes significant sintering of CaO at 800/sup 0/C. The Knudsen and Langmuir studies show that sintering of CaO is indeed catalyzed by CO/sub 2/, but at 700/sup 0/C pressures must be within about 20% of the equilibrium CaCO/sub 3/ decomposition pressure to reduce surface areas at 700/sup 0/C from 90 m/sup 2//gram to 30 m/sup 2//gram. LiCl additions, however, increase the CaCO/sub 3/ decomposition rates and markedly reduce the surface area of the product CaO. At 700/sup 0/C the CaO surface area is reduced to approx. 1 m/sup 2//gram by either decomposing CaCO/sub 3/ in the presence of LiCl or by heating high surface area CaO with LiCl. This suggests that hot pressing of CaO with LiCl which is later vaporized may be a practical means of making high-density CaO at relatively low temperatures. The equilibrium CO/sub 2/ pressure for CaCO/sub 3/ decomposition, measured by a null-point method in this study, agrees to within 10% of values measured by a static method by Shukla. Within estimated experimental errors there is no clear effect of surface area on decomposition pressure. Reaction of porous CaO with CO/sub 2/ in the range of 600 to 700/sup 0/C is time independent until the reaction is 70% complete. Reaction rate falls off sharply, probably because pores are blocked by the reaction product. It seems evident that if high surface area particles of larger relative pore volumes can be produced, then a fast linear rate may extend until reaction is 100% complete. This possibility should be investigated because effective removal of gases such as sulfur oxides by metal oxides like CaO is of great importance in the development of industrial processes that do not seriously contribute to environmental pollution.
- Research Organization:
- California Univ., Berkeley (USA). Lawrence Berkeley Lab.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5012027
- Report Number(s):
- LBL-11459
- Resource Relation:
- Other Information: Thesis
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effect of CO/sub 2/ on the oxide decomposition products of calcite
Sintering and reactivity of CaCO{sub 3}-based sorbents for in situ CO{sub 2} capture in fluidized beds under realistic calcination conditions
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CALCIUM CARBONATES
CHEMICAL REACTION KINETICS
DECOMPOSITION
HOT PRESSING
CARBON DIOXIDE
CATALYTIC EFFECTS
LITHIUM CHLORIDES
CALCIUM OXIDES
CARBON
DENSITY
ELECTRON SCANNING
ENTHALPY
IRON OXIDES
POROSITY
PRESSURE DEPENDENCE
REACTION KINETICS
SINTERING
SODIUM CARBONATES
SURFACE AREA
THERMODYNAMICS
VERY HIGH TEMPERATURE
X-RAY DIFFRACTION
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBON OXIDES
CARBONATES
CHALCOGENIDES
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
COHERENT SCATTERING
DIFFRACTION
ELEMENTS
FABRICATION
HALIDES
HALOGEN COMPOUNDS
IRON COMPOUNDS
KINETICS
LITHIUM COMPOUNDS
LITHIUM HALIDES
MATERIALS WORKING
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PRESSING
SCATTERING
SODIUM COMPOUNDS
SURFACE PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties