Local structures of metals dispersed on coal. 3; Na K-edge XANES studies on the structure of sodium gasification catalyst

Journal Article · Mon Jul 01 00:00:00 EDT 1991 · Industrial and Engineering Chemistry Research; (United States)

DOI:https://doi.org/10.1021/ie00055a037· OSTI ID:5878992

Yamashita, H; Yoshida, S; Tomita, A ^[1]

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1. Tohoku Univ., Sendai (Japan). Chemical Research Inst. of Non-Aqueous Solutions

This paper reports that in order to clarify the local structure of sodium catalyst for steam-gasification of brown coal, Na-loaded coals prepared by various methods and their heat-treated chars have been examined by X-ray absorption near edge structure (XANES) using soft X-ray. The chemical form of sodium species in the Na-loaded samples prepared by the ion-exchange with NaCl was quite similar to that prepared by the impregnation with Na{sub 2}CO{sub 3} at all heat-treatment temperatures examined. Na species are atomically dispersed with disordered local structure in the coal and in the char heat-treated at 350{degrees} C. Upon the heat treatment at 550{degrees} C, Na species aggregated to form fine Na{sub 2}CO{sub 3} particles that are likely associated with the active species for the steam gasification. On the other hand, fine NaCl particles were observed in the NaCl-impregnated coal, and the aggregation of NaCl took place upon heat treatment. The catalyst dispersion depends upon whether the surface cation-exchange sites are protonated or not during the loading process: under more basic conditions, these sites are deprotonated and ready for the interaction with Na iron.

• OSTI ID: 5878992
• Journal Information: Industrial and Engineering Chemistry Research; (United States), Vol. 30:7; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
01 COAL, LIGNITE, AND PEAT
BROWN COAL
X-RAY SPECTRA
CATALYSTS
ATOM TRANSPORT
CHARCOAL
SODIUM
ABSORPTION SPECTRA
AGGLOMERATION
COAL GASIFICATION
FINE STRUCTURE
HEAT TREATMENTS
ION EXCHANGE
K SHELL
RANDOMNESS
SODIUM CARBONATES
SODIUM CHLORIDES
SOFT X RADIATION
STEAM
TEMPERATURE RANGE 0400-1000 K
ADSORBENTS
ALKALI METAL COMPOUNDS
ALKALI METALS
CARBON COMPOUNDS
CARBONACEOUS MATERIALS
CARBONATES
CHLORIDES
CHLORINE COMPOUNDS
COAL
ELECTROMAGNETIC RADIATION
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
GASIFICATION
HALIDES
HALOGEN COMPOUNDS
IONIZING RADIATIONS
MATERIALS
METALS
NEUTRAL-PARTICLE TRANSPORT
OXYGEN COMPOUNDS
RADIATION TRANSPORT
RADIATIONS
SODIUM COMPOUNDS
SPECTRA
TEMPERATURE RANGE
THERMOCHEMICAL PROCESSES
X RADIATION
360104* - Metals & Alloys- Physical Properties
010404 - Coal
Lignite
& Peat- Gasification