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METHOD FOR VARIATION OF GRAIN SIZE IN STUDIES OF GAS-SOLID REACTIONS INVOLVING CAO
Citation:
Borgwardt, R., N. Roache, AND K. Bruce. METHOD FOR VARIATION OF GRAIN SIZE IN STUDIES OF GAS-SOLID REACTIONS INVOLVING CAO. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-86/041 (NTIS PB86196359).
Description:
The paper describes a method for varying grain size in studies of gas-solid reactions involving CaO. (Note: Introducing grain size as an independent experimental variable should contribute to improved understanding of reactions in porous solids.) Calcining 1 micrometer CaCO3 particles at maximum rate and moderate temperature (600-950 C) yields CaO with an initial B.E.T. surface area of 79 = or - 6 sq m/g, corresponding to a grain radius of about 110 A. The grain radius can be increased to any value up to at least 1800 A by controlled sintering preceding exposure to the reactive gas. At a given temperature, the grain size can be adjusted by: (1) stagnant sintering, (2) sintering with inert sweep gas, or (3) sintering with a sweep gas containing controlled concentrations of CO2. Techniques for measuring the reactivity as a function of grain size are demonstrated for the CaO/SO2 reaction.