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

Abstract

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.

Authors:
; ;  [1]
  1. Tohoku Univ., Sendai (Japan). Chemical Research Inst. of Non-Aqueous Solutions
Publication Date:
OSTI Identifier:
5878992
Resource Type:
Journal Article
Journal Name:
Industrial and Engineering Chemistry Research; (United States)
Additional Journal Information:
Journal Volume: 30:7; Journal ID: ISSN 0888-5885
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Yamashita, H, Yoshida, S, and Tomita, A. Local structures of metals dispersed on coal. 3; Na K-edge XANES studies on the structure of sodium gasification catalyst. United States: N. p., 1991. Web. doi:10.1021/ie00055a037.
Yamashita, H, Yoshida, S, & Tomita, A. Local structures of metals dispersed on coal. 3; Na K-edge XANES studies on the structure of sodium gasification catalyst. United States. https://doi.org/10.1021/ie00055a037
Yamashita, H, Yoshida, S, and Tomita, A. Mon . "Local structures of metals dispersed on coal. 3; Na K-edge XANES studies on the structure of sodium gasification catalyst". United States. https://doi.org/10.1021/ie00055a037.
@article{osti_5878992,
title = {Local structures of metals dispersed on coal. 3; Na K-edge XANES studies on the structure of sodium gasification catalyst},
author = {Yamashita, H and Yoshida, S and Tomita, A},
abstractNote = {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.},
doi = {10.1021/ie00055a037},
url = {https://www.osti.gov/biblio/5878992}, journal = {Industrial and Engineering Chemistry Research; (United States)},
issn = {0888-5885},
number = ,
volume = 30:7,
place = {United States},
year = {1991},
month = {7}
}