Determination of Sulfur in Fuel

Recently, combustion combined with various detection systems has become popular for the elemental analysis of petroleum products. Beginning with sulfur analysis and later expanded to include nitrogen and halogens, it is very widely used today. It’s versatility in terms of accommodating liquids, solids and gases have greatly expanded its areas of applications. In addition to its wide usage, a number of methods have been written by consensus organisations for this equipment. This makes the instruments readily accessible for regulatory agencies to specify for fuel analysis. 

The largest application is the determination of sulfur in fuel. These regulations have been established by the EPA for a number of years and been successfully enforced. In recent years, the permitted levels have been dropping dramatically and one of the key methods for analysis cited has been ASTM D5453.  This method is specified for combustion combined with UV-Fluorescence detection of the resulting sulfur dioxide. This method has enjoyed considerable popularity due to the low PLOQ (1 mg/kg) and the lack of any effect by oxygen. The oxygen actually aids in the combustion process producing improved results.

A very recent example of this is the new Tier 3 Regulation for gasoline. This requirement reduces the permitted sulfur level down to 10 mg/kg in nearly all cases. This regulation does not specify a particular analytical technology, but calls out Performance Based Testing as the approach to qualifying an instrument to perform this testing. In the actual regulation, D5453 is specifically mentioned as one of the methods that could be used in the Performance Testing Protocol. Studies performed by TE Instruments have confirmed the ability of the XPlorer  from TE Instruments and available to the Americans maket through HORIBA,to pass the qualification testing with flying colours. 

Another key measurement in petroleum is the presence of nitrogen in the fuel and its effect upon catalysts. Typically, the levels are expected to be low < 1- 100mg/kg) and regulatory requirements do not exist. The issue revolves more around the negative impact of the nitrogen on the catalytic processes down-stream from the refinery. As a result, methods such as D4629 have been developed for determining such nitrogen compounds. This method utilises combustion plus chemiluminescence detection of the nitrogen combustion products. The TE Instruments Explorer-N has been proven to meet these requirements. This model provides the additional benefit that it can easily be combined with the S version to create a dual element analyser for both nitrogen and sulfur.

The flexibility of the products offered by TE Instruments/HORIBA Instruments provides a long list of possible solutions for the petroleum world. From liquids like gasoline to solids like petroleum coke to gases like, LNG a variety of solutions are available. From sulfur to nitrogen to halogens at levels ranging from sub-PPM levels up to weight percent, combustion solutions are available. In most all cases, AutoSamplers are available to speed up the analysis and to minimise operator involvement. For more information on these new products and their accessories, please email Allen Bickel or Tel: (949) 242-8567.