Abstract
It is known that free radicals produced from thermal decomposition of cetane number improving agents, such as some nitrates and organic peroxides, may be contributing to increase in the cetane number of a diesel fuel. As azo compounds are known to be radical generating agents, these could be expected to perform as new cetane number improving agents. The authors have examined the effects of azo compounds on the cetane number rating of a diesel fuel.
As a result, it was found that all the azo compounds used in this work could improve the cetane number rating of a diesel fuel. As alkyl type free radicals and nitrogen may be produced from the thermal decomposition of azo compounds, the alkyl type free radicals may enhance the chain reaction in the preignition phase of the diesel fuel. It was shown that the carbon chain length of azo compounds influenced an increase in cetane number rating. From the above result we would say that a longer carbon chain could produce larger number of radicals to enhance the chain reaction. In addition, substituents of azo compounds also influenced improving cetane number rating. The fact may be attributed to the contribution of the chemical structure of alkyl radicals, produced from the thermal decomposition of substituted azo compounds, to the chain reaction.
