Method of measuring concentrations of gas mixtures

摘要

A method of measuring concentrations of gas mixtures is disclosed in which an ionic liquid and/or low vapor-pressure organic solvent is exposed to a gas mixture being tested to form a solution of the gas components in the liquid. The vapor pressure of the solution is then measured at one or more other temperatures and compared to predicted vapor pressures based on known individual vapor pressure profiles of the gas components in the liquid in order to determine the actual proportions of the components in the gas sample.

主权项

1. A method of measuring the concentration of an identified subject compound in a gaseous mixture comprising the subject compound and at least one other identified compound or compounds, comprising:
(a) exposing a liquid comprising an ionic liquid and/or a low vapor-pressure organic solvent to the gaseous mixture at a first temperature and a first pressure until the liquid and the gaseous mixture are in equilibrium, thereby forming a liquid solution comprising the ionic liquid and/or low vapor pressure organic solvent, the subject compound, and the at least one other compound or compounds; (b) isolating the liquid solution from the gaseous mixture; (c) determining a predicted vapor pressure function of the liquid solution at a second temperature as a function of the concentration of each of the subject compound and the at least one other identified compound or compounds, wherein the predicted vapor pressure of the liquid solution at a given molar concentration of each of the compounds equals the sum of the vapor pressure of each compound multiplied by its given mole percentage based on total number of moles of the subject compound and the at least one other identified compound or compounds in solution in the liquid; (d) measuring the vapor pressure of the liquid solution at the second temperature; (e) comparing the measured vapor pressure of the liquid solution at the second temperature with predicted vapor pressure function of the liquid solution at the second temperature and identifying all molar concentration profiles of the identified subject compound and the at least one other identified compound or compounds in the liquid for which the measured vapor pressure equals the predicted vapor pressure; (f) if more than one molar concentration profile of the identified subject compound and the at least one other identified compound or compounds in the liquid provides a predicted vapor pressure that equals the measured vapor pressure at the second temperature, repeating steps (c)-(e) at different temperatures until a single molar concentration profile provides a predicted vapor pressure that matches the measured vapor pressure at each of the second and additional temperatures; (g) converting the single concentration profile resulting from step (e) or step (f) by the solubility in the liquid at the first temperature of each of the identified subject compound and the at least one other identified compound or compounds, respectively to a concentration profile of the identified subject compound and the at least one other identified compound or compounds in the liquid resulting from step (a); (h) calculating a partial vapor pressure for each of the identified subject compound and the at least one other identified compound or compounds in the gaseous mixture by dividing the mole percentage of each of the identified subject compound and the at least one other identified compound or compounds in; and (i) calculating a mole percent of the identified subject compound in the gaseous mixture by dividing the partial vapor pressure of the identified subject compound from step (h) by the sum of the partial vapor pressures for each of the identified subject compound and the at least one other identified compound or compounds from step (h).