Catalytic effects of alkali metal salts in the gasification of coal char

Conference · Fri Jan 01 04:00:00 EST 1982 · Prepr. Pap. - Am. Chem. Soc., Div. Fuel Chem.; (United States)

OSTI ID:7055614

McKee, D W; Spiro, C L; Kosky, P G; Lamby, E J

This paper describes the results of a continuing study of the catalytic behavior of salts of the alkali metals in the gasification of coal char by steam and CO/sub 2/. The main purpose of this work is to investigate possible mechanisms of the catalysis and to elucidate the effects of mineral impurities on the reactivity of coal char. For this purpose the behavior of a typical char and a pure graphite powder have been compared in the presence and absence of added alkali catalysts. In a companion paper, the effects of char pyrolysis temperature, surface area and mode of catalyst addition are described. The reactivities of coal chars are obviously strongly influenced by a number of factors such as charring temperature and thermal history, pore size distribution and the presence of ubiquitous mineral impurities. However, the catalytic behavior of additives such as the alkali metal carbonates is similar for char and graphite and the same mechanisms probably operate in both cases. The main effect of the salt catalysts in both gasification reactions is to increase the pre-exponential factor of the rate equation. Changes in the apparent activation energy are small from catalyst to catalyst and on increasing the salt concentration. The most likely explanation of this effect is that the salt reacts with the char substrate to produce active sites on the surface where gasification can proceed. Increasing the amount of salt present increases the effective concentration of these active sites up to the point at which the surface becomes saturated. A plausible mechanism which has been proposed previously to account for the catalytic effects of Na/sub 2/CO/sub 3/ and K/sub 2/CO/sub 3/ in these reactions is shown in Table II.

• Research Organization: General Electric Corporate Research and Development, Schenectady, NY
• DOE Contract Number: AC21-80MC14591
• OSTI ID: 7055614
• Report Number(s): CONF-820304-Vol.2
• Conference Information: Journal Name: Prepr. Pap. - Am. Chem. Soc., Div. Fuel Chem.; (United States) Journal Volume: 27:1
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404* -- Coal
Lignite
& Peat-- Gasification
ACTIVATION ENERGY
ALKALI METAL COMPOUNDS
ARRHENIUS EQUATION
CARBON
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBONACEOUS MATERIALS
CARBONATES
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHARS
CHEMICAL ANALYSIS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COAL
COAL GASIFICATION
DATA
DEACTIVATION
ELEMENTAL MINERALS
ELEMENTS
ENERGY
ENERGY SOURCES
EQUATIONS
EXPERIMENTAL DATA
FOSSIL FUELS
FUELS
GASIFICATION
GRAPHITE
GRAVIMETRIC ANALYSIS
INFORMATION
KINETICS
MATERIALS
MINERALS
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
POTASSIUM CARBONATES
POTASSIUM COMPOUNDS
PYROLYSIS PRODUCTS
QUANTITATIVE CHEMICAL ANALYSIS
REACTION KINETICS
STEAM
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS
THERMOCHEMICAL PROCESSES