NH line broadening coefficients and intensities measurement and impurities determination in emerging applications: CCUS, Biomethane and H.

A mid-infrared quantum cascade laser (Mid-IR QCL) coupled with a Single Pass Cell and a Multi Pass Cell, was utilized to measure ammonia (NH) absorption spectroscopic parameters and determine NH impurities toward three emerging applications. We for the first time measured the pressure broadening coefficients perturbed by Air, O, N, He, CO, CH, and H and the line intensities of six NH transition lines near 1084.6 cm. The measured NH-He, NH-Air, and NH-CO broadening coefficients align with HITRAN database, while NH-H coefficients exhibit a maximum discrepancy of 46 %. Deviations between the measured line intensities and HITRAN database are minimal. Nevertheless, the uncertainties of line intensities have been significantly reduced from 20 % in HITRAN to below 3 %. The newly measured line parameters are utilized to address NH impurity requirements outlined in CCUS (ISO 27913:2016), Biomethane (EN 16723:2016), and H (ISO 14687:2019) standards. Based on the concept of optical gas standard (OGS), the NH impurity detection requirements in all three standards have been fulfilled with an uncertainty of 1.35 %. The precision of the NH-OGS is 800 part per trillion (ppt) with an integration time of 100 s. The repeatability of the NH-OGS is 130 ppt for a continuous measurement time of 48 min. Notably, the NH-OGS effectively addresses the highly nonlinear adsorption-desorption dynamics, underscoring the potential of OGS as a calibration-free and SI-traceable metrological gas analysis instrument.