Effects of pressure and composition on Raman spectra of CO-H2-CO2-CH4 mixtures.

There is great interest in the development of renewable and environmentally friendly fuel sources such as biogas and syngas for generation of heat and electricity. Raman spectroscopy is a promising method for rapid quantitative analysis of the composition of such gases. To improve the accuracy of the method, information is needed on changes in the spectra of the main components as a function of pressure and gas composition. In this work the spectral characteristics of the most intense peaks of methane, carbon monoxide, carbon dioxide and hydrogen in the range of 200-3800 cm-1 were investigated in the range of 1-25 bar for pure gases and binary mixtures. It has been revealed that, under these conditions, the change in the characteristics of pure rotational hydrogen lines is negligible, while the Q-branches of the main vibrational bands of methane, carbon monoxide and carbon dioxide shift to a few tenths of cm-1. The values of errors that can occur in the case of ignoring such changes in the spectra are estimated.