The Use of Coal Fly Ash as a Catalyst Support in the Fabrication of Carbon Nanotubes

Abstract

Carbon nanotubes (CNTs) can be used for many different purposes. An effective process of manufacturing CNTs is through fabrication in a chemical vapor deposition (CVD) apparatus from ethylene through the use of a metal catalyst and an expensive porous silica support. The goal of this project is to substitute a much less expensive material. Fly ash is described as the unburned particulate material that is derived from the combustion of fossil fuels. It is a useful material that can be used to manufacture CNTs because it is a waste product and, therefore, it is not expensive. Oil fly ash is a waste product in Saudi Arabia and has been investigated as a very inexpensive catalyst support for growing CNTs. In the United States, the petroleum refining process does not generate fly ash. Therefore, fly ash from coal combustion was investigated. Class C fly ash, which has not previously been investigated, was collected from Jeffrey Energy Center near St. Mary, Kansas, and was prepared at different weight percents of iron and at different calcination temperatures. Raman spectroscopy showed that coal fly ash is mainly composed of silica and alumina. The neutron activation analysis showed that there were other elements present in the Class C fly ash. The process used produced small nanotube growth as indicated by scanning electron microscopy. Proposed future research to examine the pore sizes of the fly ash through the use of electron microscopy could determine the best size to successfully manufacture CNTs. Research could be conducted to see whether Class F fly ash could be successfully used in the manufacturing process.