Inlet hydrogenation gas chromatography to predict mass % linear paraffin content

Area of Science:

• Petroleum Chemistry
• Catalysis
• Analytical Chemistry

Background:

• Low-temperature Fischer-Tropsch (LT-FT) process yields complex light condensate fractions requiring hydrotreating.
• Linear paraffin content is a critical specification for final hydrocarbon products and feed blending.
• Conventional gas chromatography-flame ionization detection (GC-FID) struggles with peak overlap in complex condensate analysis.

Purpose of the Study:

• To develop a simplified method for accurately predicting linear paraffin content in hydrotreated Fischer-Tropsch products.
• To evaluate the efficacy of inlet hydrogenation GC-FID for analyzing complex condensate feeds.
• To assess the feasibility of implementing this method for routine commercial process control.

Main Methods:

• Utilizing a palladium on alumina (Pd/Al2O3) catalyst within the GC inlet for pre-analysis hydrogenation.
• Optimizing catalyst mass, particle size, and bed height for efficient hydrogenation and minimal peak tailing.
• Comparing results with conventional GC-FID analysis for accuracy and simplicity.

Main Results:

• Inlet hydrogenation GC-FID successfully achieved sufficient hydrogenation without significant peak tailing using optimized Pd/Al2O3 catalyst conditions.
• The method accurately predicts the mass% linear paraffin content in final products directly from plant feed analysis.
• The catalyst demonstrated reusability for at least 20 cycles.

Conclusions:

• Inlet hydrogenation GC-FID is a simplified and accurate method for determining linear paraffin content in complex LT-FT condensate feeds.
• This technique avoids the need for additional instrumentation and complex data processing, making it suitable for commercial applications.
• The method enhances process control by enabling reliable prediction of final product composition.