(51a) Analysis of ppb Levels of H2, O2, N2, CH4, CO and CO2 in Hydrocarbon Feed Streams with a PDD Detector

The Pulsed Discharge Detector (PDD) is a highly sensitive universal GC detector with a detection limit of ~ 1 pg/sec. The sensitivity of PDD is about 1000 times higher than the most common universal TCD detector for gas analysis. A GC gas analyzer using a PDD detector has been developed to analyze polyolefin feed streams for the catalyst poisons CO, CO2 and O2. The system consists of a MoleSieve column and a PoraPLOT Q column in parallel to simultaneously analyze H2, O2, N2, CH4, CO and CO2 in a single injection with a short analytical cycle. The analyzer is capable of determining gases from low ppb to high ppm levels by switching between the 10 ports and internal loop injection valves. When determining the true level of oxygen in the process feed streams, sampling is observed to be a critical issue with air contamination of the sample cylinder.