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Title: Steam gasification of carbon: Catalyst properties

Abstract

This research uses several techniques to measure the concentration of catalyst sites and determine their stoichiometry for the catalyzed gasification of carbon. Both alkali and alkaline earth oxides are effective catalysts for accelerating the gasification rate of coal chars, but only a fraction of the catalyst appears to be in a form that is effective for gasification, and the composition of that catalyst is not established. Transient techniques with {sup 13}C labeling, are being used to study the surface processes, to measure the concentration of active sites, and to determine the specific reaction rates. We have used secondary ion mass spectrometry (SIMS) for both high surface area samples of carbon/alkali carbonate mixtures and for model carbon surfaces with deposited alkali atoms. SIMS provides a direct measure of surface composition. The combination of these results can provide knowledge of catalyst dispersion and composition, and thus indicate the way to optimally utilize carbon gasification catalysts.

Authors:
Publication Date:
Research Org.:
Colorado Univ., Boulder, CO (United States)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
5544428
Report Number(s):
DOE/PC/88915-T13
ON: DE92011621
DOE Contract Number:
FG22-88PC88915
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ALKALI METAL COMPOUNDS; CATALYTIC EFFECTS; ALKALINE EARTH METAL COMPOUNDS; CARBON; GASIFICATION; CATALYSTS; CARBON 13; CHARS; CHEMICAL REACTION KINETICS; MASS SPECTROSCOPY; PROGRESS REPORT; STEAM; STOICHIOMETRY; SURFACE PROPERTIES; CARBON ISOTOPES; DOCUMENT TYPES; ELEMENTS; EVEN-ODD NUCLEI; ISOTOPES; KINETICS; LIGHT NUCLEI; NONMETALS; NUCLEI; PYROLYSIS PRODUCTS; REACTION KINETICS; SPECTROSCOPY; STABLE ISOTOPES; THERMOCHEMICAL PROCESSES; 010404* - Coal, Lignite, & Peat- Gasification; 400201 - Chemical & Physicochemical Properties

Citation Formats

Falconer, J.L.. Steam gasification of carbon: Catalyst properties. United States: N. p., 1991. Web. doi:10.2172/5544428.
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Falconer, J.L.. Steam gasification of carbon: Catalyst properties. United States. doi:10.2172/5544428.
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Falconer, J.L.. Fri . "Steam gasification of carbon: Catalyst properties". United States. doi:10.2172/5544428. https://www.osti.gov/servlets/purl/5544428.
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@article{osti_5544428,
title = {Steam gasification of carbon: Catalyst properties},
author = {Falconer, J.L.},
abstractNote = {This research uses several techniques to measure the concentration of catalyst sites and determine their stoichiometry for the catalyzed gasification of carbon. Both alkali and alkaline earth oxides are effective catalysts for accelerating the gasification rate of coal chars, but only a fraction of the catalyst appears to be in a form that is effective for gasification, and the composition of that catalyst is not established. Transient techniques with {sup 13}C labeling, are being used to study the surface processes, to measure the concentration of active sites, and to determine the specific reaction rates. We have used secondary ion mass spectrometry (SIMS) for both high surface area samples of carbon/alkali carbonate mixtures and for model carbon surfaces with deposited alkali atoms. SIMS provides a direct measure of surface composition. The combination of these results can provide knowledge of catalyst dispersion and composition, and thus indicate the way to optimally utilize carbon gasification catalysts.},
doi = {10.2172/5544428},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Dec 13 00:00:00 EST 1991},
month = {Fri Dec 13 00:00:00 EST 1991}
}
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Technical Report:
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DOI:  10.2172/5544428
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  • ;
    This research uses three techniques to study catalyzed gasification of carbon in an effort to determine the concentration of catalyst sites on a carbon surface and thus determine how effectively a catalyst utilized for steam gasification. Both alkali and alkaline earth oxides are effective catalysts for accelerating the gasification rate of coal chars, but in many cases only a fraction of the catalysts is in a form that is effective for gasification. We will study the steam gasification of carbon in order to determine the concentration of active catalyst sites, the composition of the catalyst, and the location of themore » catalyst on the surface. Transient isotope tracing (switching reactant feed gases between H{sub 2}{sup 16}O and H{sub 2}{sup 16}O) will be used to measure the concentration of sites at steady-state reaction conditions. A steady flow of H{sub 2}{sup 16}O in He will be replaced by H{sub 2}{sup 18}O in He, while maintaining the same reaction rate, and the change in product signals will be detected with a computer-controlled mass spectrometer. Secondary ion mass spectrometry (SIMS) will be used for both high surface area samples of carbon/carbonate mixtures that are heated in steam to various temperatures and for model surfaces with deposited ions. SIMS will provide a direct measurement of surface composition. Scanning tunneling microscopy (STM), a technique that provides atomic resolution images of surfaces, will be used to determine catalyst dispersion and the location of catalyst on the surface. The interrelation of the results from these techniques (for potassium and calcium catalysts) will provide knowledge of catalyst dispersion, compositions, and utilization. Such knowledge is needed for optimal use of catalysts in steam gasification of coal char. 27 refs., 9 figs.« less

  • Coal gasification by steam is of critical importance in converting coal to gaseous products (CO, H[sub 2], CO[sub 2], CH[sub 4]) that can then be further converted to synthetic natural gas and higher hydrocarbon fuels. Alkali and alkaline earth metals (present as oxides) catalyze coal gasification reactions and cause them to occur at significantly lower temperatures. A more fundamental understanding of the mechanism of the steam gasification reaction and catalyst utilization may well lead to better production techniques, increased gasification rates, greater yields, and less waste. We are studying the gasification of carbon by steam in the presence of alkalimore » and alkaline earth oxides, using carbonates as the starting materials. Carbon dioxide gasification (CO[sub 2] + C --> 2CO) has been studied in some detail recently, but much less has been done on the actual steam gasification reaction, which is the main thrust of our work. In particular, the form of the active catalyst compound during reaction is still questioned and the dependence of the concentration of active sites on reaction parameters is not known. Until recently, no measurements of active site concentrations during reaction had been made. We have recently used transient isotope tracing to determine active site concentration during CO[sub 2] gasification. We are investigating the mechanism and the concentration of active sites for steam gasification with transient isotopic tracing. For this technique, the reactant feed is switched from H[sub 2]0 to isotopically-labeled water at the same concentration and tow rate. We can then directly measure, at reaction the concentration of active catalytic sites, their kinetic rate constants, and the presence of more than one rate constant. This procedure allows us to obtain transient kinetic data without perturbing the steady-state surface reactions.« less

  • ;
    This research uses three techniques to study catalyzed gasification of carbon in an effort to determine the concentration of catalyst sites on a carbon surface and thus determine how effectively a catalyst is utilized for steam gasification. We will study the steam gasification of carbon in order to determine the concentration of active catalyst sites, the composition of the catalyst, and the location of the catalyst on the surface. Transient isotope tracing (switching reactant feed gases between H{sub 2}{sup 16}O and H{sub 2}{sup 18}O) will be used to measure the concentration of sites at steady-state reaction conditions. Secondary ion massmore » spectroscopy (SIMS) will be used for both high surface area sample of carbon/carbonate mixtures that are heated in steam to various temperatures and for model surfaces with deposited ions. SIMS will provide a direct measurement of surface composition. Scanning tunneling microscopy (STM), a technique that provides atomic resolution images of surfaces, will be used to determine catalyst dispersion and the location of catalyst on the surface. The interrelation of the results from these techniques (for potassium and calcium catalysts) will provide knowledge of catalyst dispersion, composition, and utilization.« less

  • This research uses several techniques to measure the concentration of catalyst sites and determine their stoichiometry for the catalyzed gasification of carbon. Both alkali and alkaline earth oxides are effective catalysts for accelerating the gasification rate of coal chars, but only a fraction of the catalyst appears to be in a form that is effective for gasification, and the composition of that catalyst is not established. Transient techniques, with {sup 13}C labeling, are being used to study the surface processes, to measure the concentration of active sites, and to determine the specific reaction rates. We have used secondary ion massmore » spectrometry (SIMS) for both high surface area samples of carbon/alkali carbonate mixtures and for model carbon surfaces with deposited alkali atoms. SIMS provides a direct measure of surface composition. The combination of these results can provide knowledge of catalyst dispersion and composition, and thus indicate the way to optimally utilize carbon gasification catalysts.« less

  • This research uses several techniques to measure the concentration of catalyst sites and determine their stoichiometry for the catalyzed gasification of carbon. Both alkali and alkaline earth oxides are effective catalysts for accelerating the gasification rate of coal chars, but only a fraction of the catalyst appears to be in form that is effective for gasification, and the composition of that catalyst is not established. Transient techniques, with {sup 13}C labeling, are being used to study the surface processes, to measure concentration of active sites, and to determine the specific reaction rates. We have used secondary ion mass spectrometry (SIMS)more » for both high surface area samples of carbon/alkali carbonate mixtures and model carbon surfaces with deposited alkali atoms. SIMS provides a direct measure of surface composition. The combination of these results can provide knowledge of catalyst dispersion and composition, and thus indicate the way to optimally utilize carbon gasification catalysts.« less