J. Bimer et al., MODIFIED ACTIVE CARBONS FROM PRECURSORS ENRICHED WITH NITROGEN FUNCTIONS - SULFUR REMOVAL CAPABILITIES, Fuel, 77(6), 1998, pp. 519-525
Activated carbons were prepared by carbonization and steam activation
of nitrogen-enriched low-rank coals. N-enrichment was performed by rea
ction of ammonia or its derivatives (ammonium carbonate, hydrazine, hy
droxylamine, urea) with the carboxyl groups either naturally occurring
in coal or artificially introduced by performic oxidation. Urea at an
elevated temperature and pressure appeared to be the most efficient.
The yields of the products and their nitrogen contents suggest the che
mistry of these reactions involving not only urea itself but also its
thermal transformation products. The activated chars obtained from the
selected nitrogen-enriched precursors had considerable effective surf
ace areas and displayed excellent sulfur removal. (C) 1998 Elsevier Sc
ience Ltd. All rights reserved.