G. G. Hollman, G. Steenbruggen and M. Janssen-Jurkovic
Faculty of Earth Sciences, Department of Geochemistry, Utrecht University, PO Box 80021, 3508 TA Utrecht, The Netherlands
Abstract
The conversion of fly ash into zeolites by incubation of the fly ash with alkaline solutions is a well known process which, however, usually results in a zeolitic product which still contains significant amounts of residual fly ash. Presented here is a method by which part of the silicon in fly ash can be used for the synthesis of a maximum of 85 g of pure zeolite per kg of fly ash prior to the residual being converted into zeolite by the traditional method. The cation exchange capacities ranged from 3.6 to 4.3 meq/g for the pure zeolites and from 2.0 to 2.5 meq/g for the zeolite containing residual fly ash. Tests showed that the pure zeolites are suitable for the removal of ammonium and heavy metal ions from waste water."
First, the article is just one example of the rather abundant literature available on the manufacture of zeolites from coal ash. It is, it seems, a well-known technology.
But, not only can fly ash provide the necessary zeolite catalyst to convert coal-derived methanol into gasoline via Exxon-Mobil's process, related zeolites from coal combustion residue can also help us clean up the Nitrogen ("ammonium") and heavy metals that might be produced in the waste streams of a coal conversion facility, or a coal-fired power plant using exhaust gas scrubbers.
It's just another example, Mike, of the fact that coal science is much further advanced than is popularly known, or even, perhaps, professionally realized. Many of the inherent problems, as in pollution issues, have been solved, while many of the great potentials, as in liquid fuel conversion, remain largely undeveloped.