โ Scribed by Asfaha Iob; Mohammed A. Ali; Bassam S. Tawabini; Nureddin M. Abbas
No coin nor oath required. For personal study only.
Multicolumn valve-switching gas chromatography is commonly used in refineries for determining paraffins, olefins, naphthenes and aromatics (PONA) contents of reformate and naphtha samples. A simplified and fast alternative method, Fourier transform infrared (FT-i.r.) spectroscopy, for the same purpose was successfully used in the present work. In this method, a calibration technique which took both spectral and concentration data into consideration was developed by using the instrument manufacturer's software utilizing partial least-squares (PLS) regression analysis. For this, the mid-i.r. range (4000-4OOcm-') was subdivided into four regions that are usually attributed to different functional groups. An excellent correlation between the FT-i.r. and g.c. results was found, particularly for paraffins and aromatics (R2 = 0.97 and 0.96 respectively). The average absolute differences between the results obtained from FT-i.r. and g.c. were 1.3, 0.5, 0.2 and 0.9vol.% for paraffins, olefins, naphthenes and aromatics respectively.
๐ SIMILAR VOLUMES
Fourier transform infrared (FT-i.r.) spectroscopy was used to calculate the research octane number (RON) of naphtha feed and reformate during the course of performance evaluation of reforming catalysts. Five absorption regions that correspond to aliphatic and aromatic bands within the mid-infrared r
FT-i.r. studies of acid-demineralized and cation-loaded lignites demonstrate that exchange methods presently being used to determine carboxylic acid groups in coal produce systematic errors. An i.r. method based on intensity measurements of the 1710 cm-' carboxylic acid C=O stretching mode is report