1070-4272/05/7808-1309 + 2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 8, 2005, pp. 1309!1311. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 8, 2005,
Original Russian Text Copyright + 2005 by Talzi, Doronina, Belyi.
AND INDUSTRIAL ORGANIC CHEMISTRY
Quick Determination of the Total Content of Aromatic
Hydrocarbons in Reformer Naphthas by
H NMR Spectroscopy
V. P. Talzi, S. S. Doronina, and A. S. Belyi
Institute of Problems of Hydrocarbon Processing, Siberian Division,
Russian Academy of Sciences, Omsk, Russia
Received April 20, 2005
Abstract-A procedure for fast determination of the total content of arenes in reformer naphthas by
H NMR spectroscopy was developed and tested. Their content is determined from the ratio of the integral
intensities of the signals of aromatic protons and alkane methyl protons, using a calibration plot constructed
on the basis of GLC data.
The procedure suggested for fast (<10 min) and
relatively accurate determination of the total content
of aromatic hydrocarbons in reformer naphthas by
H NMR spectroscopy may be of use not only for re-
search but also plant laboratories, since the GLC anal-
ysis is relatively complex and time-consuming. As a
rule, laboratories of oil refineries are not equipped
with NMR spectrometers. This is caused by insuffi-
cient demand, rather than by the high cost of these
devices: The analytical problems that could be effi-
ciently solved by NMR and could justify the use of
this method under industrial conditions are yet few.
Fast and accurate determination of the total content of
aromatics in reformer naphthas could be one of such
problems. Also, we have recently developed a proce-
dure  based on
C NMR for monitoring
the composition (and thus the service characteristics)
of aqueous monoethanolamine solutions used at the
majority of oil refineries for treating process gases.
Quantitative analysis of mixtures of organic sub-
H NMR spectroscopy, from the integral
intensities of nonoverlapping signals of components,
is a routine procedure that has been used for many
decades ; it is not inferior to GLC in the accuracy.
Figures 1a and 1b show the
H NMR spectra of
a reformer naphtha sample obtained on a laboratory
rig. All the aromatic protons of its components, from
mesitylene (upfield border of the range) to naphtha-
lene (downfield border), give signals in the range
from 6.6 to 7.7 ppm; no other protons give signals in
this range. Thus, the integral intensity of signals in
this range of the
H NMR spectra can be an adequate
measure of the total content of aromatic hydrocarbons
in the sample. As the absolute intensities of signals,
as a rule, do not bear analytical information, it is nec-
essary to choose an appropriate reference signal in the
Fig. 1. (a) Low-field (aromatic protons) and (b) high-
field parts of the
H NMR spectrum of a reformer naphtha
sample. In the range 3.0!6.6 ppm, there are no signals.
(@) Chemical shift.