A 1H NMR method for the estimation of hydrogen content for all petroleum products

Abstract

Hydrogen content is an important parameter for all petroleum products, because the performance of the products for specific application depends on the concentration of hydrogen in it. Further, hydrogen content can be used as a measure for quality control during the production process and assess the quality of the products, which is governed by the catalyst used. Therefore, to get the desired petroleum products like MS and HSD, pilot scale evaluation of different catalysts plays an important role in problem solving during troubleshooting in refineries. During evaluation studies the performance of catalyst depends upon the hydrogen consumption and mass balance in any catalytic process. In order to calculate total hydrogen consumption during production of different petroleum products an effort has been made to develop a universal method based on nuclear magnetic resonance (NMR) technique, that allows estimating hydrogen content in all petroleum fractions, ranging from IBP to 530+ °C. The method uses hexamethyldisiloxane (HMDSO) for the first time as a quantitative reference standard respect to which the H content of unknown samples has been estimated. The newly developed method can also determine H/C and O/C ratio of ethanol blended fuel in a given sample without any additional experimentation. Hydrogen content for twenty five model compounds was determined along with nearly hundred petroleum fractions. There has been found to be good correlation between the existing ASTM D5291 and developed NMR spectroscopic based methods. For low boiling petroleum fractions, where ASTM D5291 is not suitable, there is no direct way to correlate the data. However, as the hydrogen content estimated for some model compounds shows a high degree of correlation R 2 = 0.998, between theoretical values and estimated values, indirectly validate the developed method. A universal NMR based method for the estimation of hydrogen content in all sort of petroleum products irrespective of their origin, composition, boiling range has been developed.