Rapid analysis of refinery gases

Refinery gas analysis, RGA, is a common application in Micro GC. In fact, it is one of the main applications that have made Micro GC so successful.

This application note presents the benefits of the latest Micro GC Fusion innovations and the performance of this analyzer in this analysis.

RGA (refinery gas) analysis covers a wide spectrum of compounds, from the smallest inert molecules (H2, He, O2, N2) to C7 hydrocarbons.
Thanks to the temperature programming, it is sometimes possible to dispense with a 4th module.
Mainly, the Alumina module allows the detailed analysis of C2 to C5. It also allows the analysis of hexane and heptane.

chromatogramme alumine rga

Compound Identification:

9 – Propane, 10 – Propylene, 11 – i-Butane, 12 – n-Butane, 13 – trans-2-butene, 14 – 1-Butene, 15 – 1-Butylene, 16 – cis-2-butane, 17 – i-Pentane, 18 – n-Pentane, 19 – 1,3-Butadiene, 20 – trans-2-pentane, 21 – methyl-2-butene, 22 – 1-Pentene, 23 – cis-2-pentane

Instrument: Micro GC Fusion 3 or 4 modules (MS5A / RTU/Alumine/Rxi)

Method :
Injector : Backflush
Column : Alumina 10m
Column temperature : 115° for 20 s, >>120°C (0.1°C/s) >170°C (0.5°C/s) for 30 seconds
Pressure : 24 psi
Carrier gas: Helium

The temperature programming brings a real advantage especially on the Alumina column. Indeed, although the ramp applied is low, it allows to keep an optimal resolution for light hydrocarbons (C3 – C4). Then, by heating progressively, to take out the heavier isomers in C5.

Depending on the application, it is possible to analyze ethane to C5 isomers on this column. In addition, the application of a temperature ramp at the end of the run also makes it possible to elute the moisture and thus avoid storing it. As a result, this column, known to be sensitive, gains significantly in stability over time.

Key words : hydrocarbons, isomers, olefins, RGA application, micro GC Fusion, chromatography, Alumina