PEFTEC - Abstract

Abstract Information :

The addition of silicon based defoamers in the petrochemical manufacturing process can cause products to contain organic silicon compounds from decomposition of the defoamer. Those silicon containing products can cause adversely effects in further processing or direct usage. For example, silicon containing naphtha can deactivate catalysts for downstream processing. Silicon containing gasoline, denatured ethanol, and their blends can foul vehicle components such as spark plug, piston and catalytic converter in a motor vehicle. Silica deposits from combustion of contaminated fuel on the oxygen sensor in the engine exhaust can cause a breakdown in the electrical feedback to the engine electronic control unit, resulting in a complete loss of vehicle drivability.

Because of the adversely effects of silicon to motor vehicles, Si contents in gasoline or diesel were set at <1ppm or Not Detected according to Worldwide Fuel Charter published in 2013 (5th edition). The detection of Si is difficult. For example, ASTM D7757 an X-Ray Fluorescence method has detection limit of 3 ppm and obviously cannot meet the <1 ppm requirement specified in Worldwide Fuel Charter.

GC-AED (Gas Chromatography - Atomic Emission Detector) as a potential analytical tool can meet the detection limit if it can further be improved to increase selectivity toward C. Beside the potential of low detection limit that can meet the specification, GC-AED has also advantages in speciation and quantitation of components. The speciation and quantitation of components provide a mean for finding the source of contamination for isolation and eradication.

It has been shown that for single component, a detection limit of 0.5 ppm can be reached using the 2nd generation GC-AED with hydrogen and oxygen as reaction gases. The Si to C selectivity of 30,000 was estimated by Agilent. Diatomic emission continent spectra from CO is the main cause to limit AED selectivity toward C.

JAS has developed the 3rd generation AED with improved electronic boards and detector design allowing the use of other reaction gases to replace O2. The new CCD detector without moving parts can reach 100Hz for data acquisition which makes it suitable for GCxGC applications. The elimination of oxygen as a reaction gas has shown a significant reduction of diatomic emission and improvement in Si to C selectivity and thus the detection limit. Due to the geometric limitation, we use Si 222 line instead of more intense Si 252 line. Although the intensity of Si 222 line is only ˜20 to 25% of Si 252, we have found that the detection limit of Si in a gasoline sample can reach ˜ 0.1 ppm for each peak.

In this paper we will present the application using the newly designed AED coupled with Gas Chromatography for the analysis of Si in petroleum products such as gasoline and diesel. The effects of data acquisition rate, reaction gas and GC conditions on the selectivity and detection limit of Si by AED as well as the linear dynamic range of Si will be reported.