Evaluating Hydrogen Carriers Effectively With Gas Chromatography

10 Hydrogen Carrier 􀀱􀁓􀁐􀁅􀁖􀁄􀁕 The Nexis GC-2030 combines excellent performance, including the world's highest level of sensitivity and reproducibility, with excellent scalability as it can be equipped with multiple injection devices and detectors to meet the analysis requirements of the component and concentration to be measured. Gas Chromatograph Nexis GC-2030 ■ Measurement of Gas Composition Before and After Ammonia Synthesis The high-end Nexis GC-2030 gas chromatograph equipped with two thermal conductivity detectors (TCD), and samples are introduced into both detectors with a single injection. Simultaneous analysis of three components present during ammonia synthesis is possible by measuring hydrogen in one analysis line and nitrogen and ammonia in the other. ■ Measurement of Impurities in Ammonia Gas Ammonia used in semiconductor manufacturing processes requires high purity control to avoid any issues caused by trace impurities. By combining multiple analytical columns with a gas chromatograph, trace components can be separated and sub-ppm level impurities in ammonia can be measured. • Simultaneous analysis of hydrogen, nitrogen, and ammonia, which are raw materials for ammonia, is possible using multiple detectors. benefits • A nalysis of impurities in ammonia and raw gas is possible. Gas composition related to ammonia synthesis can be analyzed using gas chromatography. Evaluation of Ammonia Synthesis Gas Chromatograph Fig. 1 TCD-1 Measurement of Hydrogen Concentration in Mixing Gas Fig. 2 TCD-2 Measurement of Nitrogen and Ammonia Concentrations in Mixing Gas H2 37.3% N2 31.3% NH3 31.4% Fig. 3 Measurement of Impurities in Ammonia Using TCD (10 ppm each) 0 2.0 4.0 O2+Ar N2 CH4 CO 6.0 8.0 10.0 12.0 11 Hydrogen Carrier This instrument separates each compound in the sample, and then quantifies each component using a detector. The data obtained tells the analyst what compounds are in the sample and in what quantities. Barrier discharge ionization detector (BID) Shimadzu's proprietary technology has been adopted for the BID, which incorporates ionization via a new dielectric barrier discharge plasma. It is more sensitive than conventional detectors, is able to detect components that were difficult to detect using FID, TCD and other all-purpose detectors, and delivers long-term stability. Gas Chromatograph Nexis GC-2030 􀀱􀁓􀁐􀁅􀁖􀁄􀁕 ■ Measurement Results (Extract) Ammonia and methylamine were diluted with water to prepare solutions at 4.8 ppm and 24 ppm, respectively, and the solutions were then measured by GC-BID. The 4.8 ppm and 24 ppm chromatograms are shown in Fig. 1 and the linearity is shown in Fig. 2. Calculating the lower limit of detection (S/N = 3) from the 4.8 ppm S/N ratio, the results indicated 1.2 ppm for ammonia and 2.5 ppm for methylamine. Linearity may be sacrificed at low concentrations of components that display adsorption. In this analysis, good linearity was obtained over the range, including at 4.8 ppm and 24 ppm. Using a barrier discharge ionization detector (BID) with a gas chromatograph enables a ppm-order analysis of ammonia in water. benefits Ammonia is a focus of attention as a hydrogen carrier because of its large energy density per unit volume and how easy it is to store and transport. At the same time, it is known to be toxic and bad smelling, so leakage into the environment is viewed as a problem. High-Sensitivity Analysis of Ammonia in Water Gas Chromatograph Nexis GC-2030 + BID-2030 Fig. 1 Chromatograms of 4.8 ppm and 24 ppm Standard Solutions Detection Lower Limit Ammonia (1.2 ppm) Methylamine (2.5 ppm) Ammonia Methylamine 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 min 24 ppm 4.8 ppm Fig. 2 Linearity of Ammonia and Methylamine (4.8 ppm, 24 ppm) Area (μV×s) Area (μV×s) Concentration (v/v ppm) Concentration (v/v ppm) R^2 = 0.9999814 Ammonia 0.0 25.0 50.0 75.0 100.0 R^2 = 0.9989209 Methylamine 0.0 25.0 50.0 75.0 100.0 􀀢􀁑􀁑􀁍􀁊􀁄􀁂􀁕􀁊􀁐􀁏 12 Hydrogen Carrier 􀀢􀁑􀁑􀁍􀁊􀁄􀁂􀁕􀁊􀁐􀁏 􀀢􀁑􀁑􀁍􀁊􀁄􀁂􀁕􀁊􀁐􀁏 ■ Measurement Results (Extract) With hydrogen and methane as the target analytes, hexanes, toluene and water were used as the dissolving solutions in this experiment. Gas samples at the concentrations of 10, 50, 100, 500, 1,000, and 5,000 ppm (v/v) were prepared by diluting the standard gases of hydrogen and methane with indoor air. Using a 100 μL gas tight syringe, 100 μL of each calibrator was injected into a gas chromatograph (GC) to establish a calibration curve. The chromatogram for hydrogen dissolved in water, hexane, toluene, and other solutions is shown in Fig. 2. ■ Measurement Results (Extract) Fig. 1 shows the chromatogram from a batch analysis of five gasses, including hydrogen, other inorganic gases, and low-level hydrocarbons, using a dual BID system. Using barrier discharge ionization detectors (BID) enables the high-sensitivity analysis of hydrogen in solution. benefits Inorganic gases and low-level hydrocarbons can be batch analyzed quickly and with high sensitivity by using a dual BID system equipped with two detectors and two columns. benefits To use the hydrogen in MCH or ammonia, it must be removed from the hydrogen carrier, so analyses of the hydrogen in the solution and gas are necessary. Only certain columns can be used for separation of inorganic gases and light hydrocarbons, and it is sometimes impossible to use a single column to separate all of the target components. The Nexis GC-2030 can be equipped with two BID detectors simultaneously and supports two detectors and columns at the same time. Analysis of Hydrogen in Solution Analysis of Hydrogen in Gas Gas Chromatograph Fig. 2 Chromatogram Overlay of Hydrogen Dissolved in Hexanes, Toluene and Water Fig. 1 Chromatogram for 5 ppm Mixed Gas 1: Hydrogen 2: Oxygen 3: Nitrogen 4: Methane 5: Carbon monoxide Fig. 1 Calibration Curve of Hydrogen (1, 5, 10, 50, 100 nL) Area Volume (nL) 13 Hydrogen Carrier 􀀱􀁓􀁐􀁅􀁖􀁄􀁕 􀀢􀁑􀁑􀁍􀁊􀁄􀁂􀁕􀁊􀁐􀁏 With this system, the compounds in the sample are separated by component using the gas chromatograph (GC) and these components are ionized in order to analyze their mass. Qualitative information is obtained on the components, enabling a more accurate qualitative analysis than with GC. Any impurities can also be separated. In addition, higher sensitivity enables lower concentration measurements. The pump has a high discharge capacity, so sufficient measurements are possible when using hydrogen as the carrier gas. Gas Chromatograph Mass Spectrometer GCMS-QP2050 ■ Measurement Results (Extract) Fig. 1 shows the TIC chromatogram from a GC-MS analysis of 56 organic solvents, including toluene and MCH, eluted with carbon disulfide. Many organic solvents, including toluene and MCH, in a solution can be analyzed using GC-MS. benefits When MCH is used as the hydrogen carrier, toluene is produced when the hydrogen is removed from the MCH, so the MCH and toluene in the solution must be analyzed. Analysis of Toluene, Methylcyclohexane (MCH) in Solution Gas Chromatograph Mass Spectrometer 1. n-Hexane, 2. Ethyl ether, 3. Methylcyclohexane, 4. Acetone, 5. Methyl acetate, 6. trans-1,2-Dichloroethylene, 7. Tetrahydrofuran, 8. Carbon tetrachloride, 9. 1,1,1-Trichloroethane, 10. Ethyl Acetate, 11. Isopropyl acetate, 12. Methyl ethyl ketone, 13. Dichloromethane, 14. Benzene, 15. n-Propyl acetate, 16. cis-1,2-Dichloroethylene, 17. Trichloroethylene, 18. Methyl isobutyl ketone, 19. Isobutyl acetate, 20. 2-Butanol, 21. Chloroform, 22. Tetrachloroethylene, 23. Toluene, 24. 1,2-Dichloropropane, 25. 1,4-Dioxane, 26. 1,2-Dichloroethane, 27. n-Butyl acetate, 28. Methyl n-butyl ketone, 29. Isobutyl alcohol, 30. Isopentyl acetate, 31. Ethylbenzene, 32. p-Xylene, 33. 1-Butanol, 34. m-Xylene, 35. n-Pentyl acetate, 36. Methyl Cellosolve, 37. o-Xylene, 38. Isopentyl alcohol, 39. Cellosolve, 40. Chlorobenzene, 41. Styrene, 42. Cellosolve acetate, 43. Cyclohexanone, 44. 2-Methylcyclohexanone, 45. N,N-Dimethylformamide, 46. 3-Methylcyclohexanone, 47. 4-Methylcyclohexanone, 48. Butyl Cellosolve, 49. Cyclohexanol, 50. cis-2-Methylcyclohexanol, 51. trans-2-methyl-cyclohexanol, 52. 1,1,2,2-Tetrachloroethane, 53. ortho-Dichlorobenzene, 54. o-Cresol, 55. p-Cresol, 56. m-Cresol Fig.1 Total Ion Current Chromatogram for 56 Organic Solvents (Stabilwax)