General Methods for Fuel Analysis I: Analysis of Elements and Nonhydrocarbon Compounds

This article is the first in a series of articles aimed at introducing common methods for evaluating gaseous, liquid, and solid conventional and alternative fuels. The paper presents an overview of the monitored elements and their non-hydrocarbon compounds for individual liquid and gaseous fuels. Methods for determining these analytes are also presented. The significance of these determinations is also discussed. The emphasis is given mainly on standardized parameters and tests, but in some cases, we discuss also non-standardized tests or analyses not required by standards. The main goal of the article is to provide a comprehensive overview of elements and their non-hydrocarbon compounds monitored for individual fuels, the reason why these analytes are monitored, and what methods are used for this monitoring. Practically all liquid fuels discussed in this article are monitored for sulfur content. The limit value for sulfur content is 10 mg/kg, with the exception of paraffinic diesel fuel and some synthetic liquid fuels. Phosphorus content is monitored in all fuels containing a higher proportion of biocomponents. Examples such fuels are ethanol, FAME, E85, E95, and rapeseed oil. For fuels containing ethanol, the oxygen content (E5, E10) and alcohol content (E5, E10, E85 and E95), or ether content (E5, E10, E85) are also monitored. Among the minor elements, lead (E5, E10, E95), manganese (E5, E10, B7, and B10), copper (ethanol, E95), alkali metals (FAME) and alkaline earth metals (FAME and rape oil) are monitored. As with liquid fuels, the sulfur content of gaseous fuels is also monitored. Of the sulfur compounds, the sum of sulfur and carbonyl sulfide content is monitored for CNG, LNG, and their bioequivalents. For LPG for internal combustion engines, sulfane is determined qualitatively, whereas for LPG for heating purposes, the sulfur content is quantified. In the case of LPG for heating purposes, the ammonia content is determined qualitatively, and in the case of biogas according to ČSN 65 6514, the content of nitrogenous impurities except to nitrogen, and the sum of the content of carbon dioxide, nitrogen and oxygen are also evaluated.