Fuel Composition Analysis and Studies on Fuel Adulteration using State-of-Art High Performance Liquid Chromatography Coupled with High Resolution Gas Chromatography 990046

A strong co-relation exists between composition of a fuel and the exhaust that is formed during combustion. In this context, with the stringent emission regulations, the chemical characteristics of fuels have become of increasing importance. Petroleum derived fuels are complex mixtures of hydrocarbons containing hundreds of different aliphatic and aromatic compounds. EPA, to control the exhaust pollutants, regularly publishes the international updates on limits for aromatic, olefins and saturate contents in gasoline fuels. The Indian legislative standard DOC No. MOST/CMVR/TAP-115/116 specifies olefin and aromatic contents to 20% and 45% max. by volume respectively for the Indian reference petrol. While, Indian specification IS: 2796-1995 has laid down the limits for benzene content to 5% max. by volume for leaded regular, unleaded regular & unleaded premium gasoline for the year 2000 norms. However, there is no control for aromatic in diesel fuels in the Indian specification IS 1460-1995. Essentially diesel fuels are olefin free with typical chemical class composition of 15-30% aromatics and 70-80% saturated aliphatic [1]. The polycyclic aromatic fraction of diesel fuel contains three, four and larger ring aromatics. These compounds are thought to contribute towards diesel exhaust polycyclic aromatic compounds (PAC), both as unburned fuel and through pyrolysis plus pyrosynthetic route.

The fuel droplet core, depending upon the size for surface evaporation and availability of oxygen for combustion, undergoes “pyrolysis”. Then the unstable compounds forms some ring chains the process being defined as “pyrosynthesis”. Many PAC are listed as EPA priority pollutants because they are known or suspected mutagens and/or carcinogens. The percentage of diesel powered vehicles on the road is increasing significantly owing to their superior fuel economy over gasoline powered vehicles. As diesel exhaust emissions are increasingly being viewed as an important contributor to environmental pollution. Accurate analysis of fuel composition and PAC in both diesel fuels and exhaust particulate is necessary to understand and control the problem. Moreover based on research findings formulation of diesel quality standards should be reviewed to improve public safety. Fuel specifications for commercial fuel and reference fuel for India year 2000 emission norms have recently been published. The worry is that the standard does not speak about the composition except certain physico-chemical properties nor seem to have taken cognisance of serious repurcussions of the specific class of aromatics present both from the point of view of gaseous and PNA emission.

The recent european auto oil programme did a lot of research work on fuel vs emission taking for granted their fuel quality. However, more work is needed to get further details of fuel quality. The development of suitable methods for the determination of fuel constituents has also been the subject of interest of intense research for the last many years.

The present paper is on the experimental techniques developed on High Performance Liquid Chromatography Coupled with High Resolution Gas Chromatography (HPLC/HRGC) which are used for ascertaining the composition of Indian commercial verses the reference fuel used in the developed countries. The results and discussions reveal that the Indian gasoline and diesel fuels need to be reformulated to meet the future demands of emission regulations and to be environmentally friendly with less carcinogenic and mutagenic pollutants.

The paper also discusses the laboratory procedure developed to study diesel fuel adulteration with kerosene and its effects on aromatic and aliphatic contents