Quantification of H2 and Hydrocarbons in CO2 Using TCD-to-Jetanizer -FID Series Connection

Quantification of H2 and Hydrocarbons in CO2 Using TCD-to-Jetanizer-FID Series Connection — Summary

Significance of the Topic

Gas-phase analysis of products and by-products from CO2 conversion reactions (e.g., hydrogenation, electrochemical reduction, photocatalysis) is essential for evaluating catalyst performance, reaction selectivity, and process optimization. Reliable simultaneous quantification of permanent gases (H2, CO) and light hydrocarbons (CH4, C2 species) including low‑volatility oxygenates such as methanol reduces experimental complexity and accelerates data throughput for research and QA/QC in clean‑energy and catalyst development.

Objectives and Study Overview

• Demonstrate a single‑GC analytical approach to simultaneously quantify H2, CO, CO2, light hydrocarbons (up to C3), and methanol in CO2 conversion gas streams.
• Use nitrogen as carrier gas to enhance TCD sensitivity for H2 and avoid dependence on helium.
• Employ a serial detector arrangement (TCD upstream, Jetanizer‑FID downstream) and an inlet split to enable concurrent analysis of inorganic gases, hydrocarbons, and low‑volatility alcohols without complex valve switching or multiple instruments.
• Evaluate linearity, sensitivity, and reproducibility for representative calibration levels and catalytic reaction samples.

Methodology

• Single GC platform: Brevis GC‑2050 with GI‑30 automatic gas injector (SPI) for reproducible gaseous injections and low leak vaporization.
• Detector configuration: TCD connected in series to a Jetanizer‑FID (the Jetanizer is an FID jet packed with a reduction catalyst to convert CO/CO2 to CH4 for FID detection of inorganic carbon species and organics).
• Carrier gas: Nitrogen chosen to improve thermal conductivity contrast for H2 detection in the TCD and to enable use of N2 as FID makeup gas.
• Column strategy: MICROPACKED‑ST packed column (1–2 m × 1.0 mm ID) to separate permanent gases (H2, CO) and light hydrocarbons; when methanol is included, an SH‑Q‑BOND capillary column (30 m × 0.32 mm × 10 µm) is used in conjunction with MICROPACKED‑ST via an INJ2‑way branch and inlet split to separate hydrocarbons/alcohols and permanent gases within a single run.
• Sampling/calibration: Multilevel gas standards prepared in vacuum sampling bottles using CO2 as balance gas. Calibration ranges used: H2 at 100, 1,000, 10,000 ppm; CO, CH4, C2H4 at 1, 10, 100, 1,000 ppm. Analysis used split injection to route appropriate fractions to columns/detectors.
• Typical oven and detector settings were optimized (example programs and detector temperatures included in the original study) to balance separation, run time, and detector response.

Used Instrumentation

• GC: Shimadzu Brevis GC‑2050.
• Auto gas injector: GI‑30 (SPI inlet with low‑leak vaporization chamber).
• Detectors: Thermal Conductivity Detector (TCD) upstream; Jetanizer‑FID downstream; conventional FID used for hydrocarbon/alcohol column.
• Columns: MICROPACKED‑ST (packed column for H2/CO/light hydrocarbons), SH‑Q‑BOND (capillary for hydrocarbons and methanol).
• Ancillary parts: metal transfer columns/ferrules/unions as required for heated/unheated transfer, INJ2‑way branch unit for split flow configuration.

Main Results and Discussion

• Linearity: Calibration curves for H2 (TCD) and CO, CH4, C2H4 (Jetanizer‑FID) exhibited excellent linearity with R2 ≥ 0.999 across stated ranges.
• Sensitivity: Using N2 carrier, the TCD provided sufficient sensitivity to quantify H2 down to 100 ppm. CO and light hydrocarbons were quantified using Jetanizer‑FID with practical detection at 1 ppm levels; signal‑to‑noise (S/N) values at lowest calibration points were high (e.g., H2 S/N ≈ 97 at 100 ppm; CO and hydrocarbons S/N > 40–57 at 1 ppm for specified conditions).
• Reproducibility: Area %RSD over six consecutive injections was excellent for most analytes (<1% for H2, CO, CH4, C2 species across various concentrations). High concentration H2 and CO measurements (e.g., 100,000 ppm) showed very low %RSD (≈0.11–0.13). Methanol showed concentration‑dependent reproducibility: 0.91% RSD at 5 ppm but deteriorated to 5.73% RSD at 100 ppm, attributed to adsorption/retention and volatility behavior on packed column requiring periodic conditioning.
• Chromatographic performance: Representative chromatograms showed baseline separation of permanent gases, light hydrocarbons and alcohol peaks when using the combined column/inlet split configuration. Use of unheated transfer segments aided handling of gaseous analytes.
• Practical considerations: Jetanizer‑FID enabled quantification of CO (and CO2 conversion) by catalytic conversion to CH4 in the FID jet, while TCD with N2 carrier provided selective H2 detection. The inlet split approach avoided complex multi‑GC or multi‑valve setups for simultaneous inorganic and organic analysis.

Benefits and Practical Applications

• Single‑instrument solution for simultaneous quantification of permanent gases (H2, CO, CO2) and light hydrocarbons including methanol, reducing instrument footprint and simplifying workflows.
• Nitrogen carrier enables sensitive H2 detection by TCD without relying on helium, offering cost/availability advantages.
• GI‑30 auto gas injector provides automated, reproducible gaseous injections for routine sample throughput and better quantitation precision.
• Jetanizer‑FID allows detection of otherwise TCD‑insensitive organics and converts CO/CO2 to detectable CH4, enhancing overall capability for CO2 conversion product analysis.
• Applicable to catalyst screening, lab‑scale CO2 conversion studies, process R&D, and QA/QC where mixed gas/vapor streams must be quantified concurrently.

Future Trends and Potential Uses

• Integration with automated sampling/manifold systems and online sampling from reactors or electrolyzers to provide real‑time monitoring of CO2 conversion processes.
• Further optimization of column materials and inlet conditioning to improve reproducibility for low‑volatility oxygenates such as methanol and higher alcohols.
• Development of dedicated software workflows for multi‑detector quantitation (TCD + Jetanizer‑FID) and automated calibration/quality checks to streamline routine operation in research and production environments.
• Expansion to broader analyte sets (e.g., sulfur‑containing gases, ammonia) by combining selective precolumns or trap modules while maintaining single‑GC simplicity.

Conclusion

A serial TCD‑to‑Jetanizer‑FID configuration on a single Brevis GC‑2050, combined with a GI‑30 auto gas injector and an inlet split, provides a practical and robust approach to simultaneously quantify H2, CO, CO2, light hydrocarbons, and methanol in CO2 conversion gas streams. The method demonstrates excellent linearity and reproducibility for most analytes, leverages N2 carrier gas to enhance H2 detection, and reduces instrumentation complexity compared with multi‑GC or valve‑switched systems. Attention to column selection and periodic conditioning is required when low‑volatility oxygenates are present.

References

• Shimadzu Corporation. Quantification of H2 and Hydrocarbons in CO2 Using TCD‑to‑Jetanizer‑FID Series Connection. Application News 01‑00956‑EN. First Edition: Apr. 2026.
• Related application: Shimadzu Corporation. Gas Analysis for CO2 Conversion Using a GI‑30 Auto Gas Injector. Application News 01‑00964‑EN.