Importance of catalyst dispersion in the gasification of lignite chars

Journal Article · Mon Aug 01 04:00:00 EDT 1983 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(83)90205-1· OSTI ID:5688333

Radovic, L R; Walker, Jr, P L; Jenkins, R G

Lignite chars were prepared in N/sub 2/ under widely varying conditions of pyrolysis heating rate, temperature, and residence time. Their reactivities were measured by isothermal thermogravimetric analysis in 0.1 MPa air. A major decrease in char reactivity was observed with increasing severity of heat-treatment conditions. The relatively high gasification reactivity of lignite chars, compared to those obtained from higher rank coals, is due to the catalytic effect of the initially very highly dispersed CaO on the char surface. Char deactivation is caused primarily by CaO crystallite growth, measured by X-ray diffraction line broadening. When the reactivities of the various chars are expressed as turnover frequencis, i.e., per unit catalyst site, differences in observed rates of about 200 times are reduced to within 1 order of magnitude. Thus, it has been shown that the commonly observed and heretofore empirically treated lignite char deactivation with increasing severity of pyrolysis conditions can be correlated with a decrease in a measurable fundamental property of the chars; catalyst dispersion. 6 figures, 2 tables.

• Research Organization: Pennsylvania State Univ., University Park
• OSTI ID: 5688333
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 82:2; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404* -- Coal
Lignite
& Peat-- Gasification
ADSORPTION ISOTHERMS
ALKALINE EARTH METAL COMPOUNDS
BROWN COAL
CALCIUM COMPOUNDS
CALCIUM OXIDES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBONACEOUS MATERIALS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHARS
CHEMICAL ANALYSIS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COAL
COAL GASIFICATION
COHERENT SCATTERING
COVER GAS
DATA
DECOMPOSITION
DIFFRACTION
DISPERSIONS
ELECTRON MICROSCOPY
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY SOURCES
EXPERIMENTAL DATA
FLUIDS
FOSSIL FUELS
FUELS
GASES
GASIFICATION
GRAVIMETRIC ANALYSIS
HEATING RATE
HIGH TEMPERATURE
INERT ATMOSPHERE
INFORMATION
ISOTHERM
KINETICS
LIGNITE
MATERIALS
MICROSCOPY
NITROGEN
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PYROLYSIS
PYROLYSIS PRODUCTS
QUANTITATIVE CHEMICAL ANALYSIS
REACTION KINETICS
SCANNING ELECTRON MICROSCOPY
SCATTERING
SORPTIVE PROPERTIES
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS
THERMOCHEMICAL PROCESSES
TIME DEPENDENCE
VERY HIGH TEMPERATURE
X-RAY DIFFRACTION