Estimation of bromine number of petroleum distillates by NMR spectroscopy

In the present work, a direct and fast method based on NMR spectroscopic techniques (H-1/C-13) has been developed for the estimation of bromine number of gasoline and coker kerosine (CK) fuel samples of boiling range 50-250 degrees C. Two approaches have been adopted. In the first, the percentage unsaturation (I-H(o)%) in the chemical shift range of 4.6-6.6 ppm (H-1 NMR) has been correlated with the predetermined bromine number of the samples. The I-H(o)% versus bromine number gives a straight line, with proportionality constant K = 16.2 (FCC) and 9.3 (Coker) products. In the second approach, the relative number of double bonds (D) in the sample has been determined by H-1/C-13 NMR method. The bromine number has been estimated using developed equations. A very goad correlation (correlation coefficient, R-2 = 0.98) has been observed between the NMR methods and the standard method (IP: 129/81, reapproved 1988). The C-13 NMR method is independent of the nature of olefins, source of feed, and catalyst/cracking conditions compared to the H-1 NMR spectroscopy method.