Some of the key processes in the petrochemical industry are conversions of high-grade ethylene (C2) and propane/propylene (C3) feedstocks into end products (polyethylene, polypropylene) and intermediates such as 1-butene. These, of course, are the building blocks for plastics and a wide range of products, and are a large industry with 55 million metric tons of polypropylene produced in 20131. Unfortunately, even trace levels of sulfur species H2S and COS, which are often entrained in C2 and C3 feedstocks, corrode pipes and equipment, inhibit or damage catalyst beds, and lower product yield and purity2. The need for a fast, reliable analysis method for H2S and COS in both C2 and C3 feedstocks is obvious, but sulfur in C2 and C3 is a difficult application, owing to the poor separation of the impurities from the matrix when coupled with the quenching of the PFPD detector signal by propane/propylene. This whitepaper presents a fast, reliable, and robust method for the analysis of sulfur contaminants in C2 and C3 feedstocks that makes use of an automated gas loop injection system, separation by gas chromatography, and pulsed-flame photometric detection that can detect sulfur at better than 0.1 ppmv.

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5383 Pulsed Flame Photometric Detector (PFPD)

The Model 5383 Pulsed Flame Photometric Detector (PFPD) uses superior sensitivity and increased selectivity to easily and accurately analyze sulfur, phosphorus, and 26 other elements.

The superior sensitivity of the 5383 PFPD makes it the instrument of choice for the analysis of sulfur, phosphorus, and other elements. Its linear, equimolar response to sulfur allows selective measurement of individual sulfur species from low ppb to ppm levels, and total sulfur as the sum of individual peaks. The unique capability to obtain simultaneous sulfur and hydrocarbon chromatograms from a single PFPD detector sets it apart from other sulfur detection technologies.

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