PREPARATION OF FULLERENES BY INCOMPLETE

点击翻译按钮获取中文摘要

The purpose of this project is to improve the method of manufacturing fullerenes, especially buckminsterfullerene C60, by incomplete combustion of hydrocarbons, so that fullerenes can be produced in large scale by continuous scheme in the near future.In the first year of the project, we concentrated on the analysis of fullerenes in commercial soot products with the hope of obtaining clues for fuel, burning temperatures, purification and other conditions. After examining a number of traditional as well as modern products from soots, we found that Chinese ink sticks and some charcoals constantly analyzed positively for buckminsterfullerene and sometimes C70 as well. New ink sticks usually contain about 0.1ppm of C60. This level of C60 can be produced by simple burning of benzene, cyclohexane and other hydrocarbons in small flames in air and also agrees with the level detected in ancient geological objects like the black clay from K-T layr, which has been considered to arise from wildfire … More caused by bolide impact. Interestingly enough we found that the C60 contents in Chinese ink sticks decrease with time over a period of several hundred years conforming to the rate law of the first order. We interpret the decrease not by spontaneous decomposition but by Brownian type movements of spherical and smooth C60 molecules in the microstructure of ink sticks.In the second year, we performed numerous burning tests using simple free burning apparatus, while changing fuels and catalysts. Preliminary as they are, we obtained two encouraging results by using metallocene catalysts : (1) addition of catalytic amounts of ferrocence led to up to 500% increase in the yield of C60, and (2) addition of catalytic amounts of nickellocene and titanocene decreased the yields of 60, but produced a new intense peak in the HPLC analysis of the extract with Rf value of 0.65 relative to C60, which is supposed to be an intermediate similar to what was once reported by Howard et al.As the results of these preliminary experiments, we have designed an experimental burning apparatus, which is safe and can be conveniently used for seeking various burning conditions for searching catalysts. Less