Dynamic Approach for the Estimation of Olefins in Cracked Fuel Range Products of Variable Nature and Composition by ¹H NMR Spectroscopy

Abstract

A dynamic 1H NMR-based method for the estimation of olefin content in all cracked fuel range products, in general, and in gasoline/naphtha streams, in particular, irrespective of types and composition of olefins and boiling range of samples has been developed. This is in continuation of our earlier works where two methods were described for the determination of hydrocarbon types in straight-run gasoline (no olefins) and cracked full range gasoline/naphtha (with olefins). The average absolute number of unsaturated hydrogen (H) in the olefinic region (4.4–6.5 ppm) was directly estimated with the help of a 1H NMR spectrum using dynamic variables in terms of differential population of various kinds of olefins. The average alkyl chain length (n) was estimated by various methods including 13C NMR and carbon number distribution by a gas chromatography-based detailed hydrocarbon analyzer [DHA, ASTM D6730-01(2016)] and simulated distillation [ASTM D2887-16a] data. The percentage of unsaturated hydrogen (% UH) in an average olefin was then obtained providing a multiplication factor (f o) by which the weight percentage of olefin is estimated using a normalized 1H NMR spectrum. The dynamic estimation of H and n for each sample removes the possibilities of errors in the estimation. The method has efficiently been extended to coker kero and coker diesel range products where there has been no method available for olefin estimation. The method was validated by using DHA following ASTM D6730, by the Reformulyzer-based ASTM D6839 method, and finally by fluorescent indicator adsorption following ASTM D1319. All the methods were compared. Whereas the proposed NMR method is extremely general, free from manual error, the limitations of existing ASTM methods and the old NMR method vis á vis a new NMR method are also discussed.

Proton Nuclear Magnetic Resonance (1H-NMR) Methodology for Monolefin Analysis: Application to Aquaprocessing-Upgraded Bitumen

“…It is possible to observe that the olefins present in this sample correspond to the groups O1, O2, O3, and O4 following the nomenclature suggested by others before (see Figure 4). 7,27 This finding is deemed important from a process point of view, i.e., the monolefins surviving the process the most were found . 1 H-NMR calibration of olefinic protons using blends prepared with different types of naphthas having known olefin contents (via SFC).…”

“…Energy & Fuels pubs.acs.org/EF Article to belong to the internal olefin groups O3 and O4, i.e., those described more refractory to convert as reported by others before. 7,27 Figure 12 presents the monolefin contents calculated for AQP samples using eq 1, plotted as a function of viscosity reduction, which is the most important parameter governing partially upgraded bitumen transportability. Precision of the replicated analyses presented in Figure 12 indicated <11% relative repeatabilities, matching the 10 %RSD reported before for SFC group-type analysis of olefins (see Section 3.1).…”

Análise De Amostras De Combustíveis Por Fotometria, Nir Portátil E RMN De 1 H – Uma Comparação Com Os Resultados Encontrados Por Técnicas Normatizadas

“…15 Na análise de combustíveis, as principais regiões de interesse são as referentes aos grupos de hidrogênios alifáticos, aromáticos e olefínicos, cujos deslocamentos químicos são consolidados na literatura. 10,[16][17][18][19] Outra técnica bastante empregada no estudo de combustíveis devido principalmente ao seu baixo custo e simplicidade é a espectroscopia na região do infravermelho próximo (NIR). A capacidade do NIR em obter informações sobre ligações químicas distintas permite estudar os compostos constituintes da gasolina, etanol e óleo diesel a partir de grupos funcionais moleculares do tipo C-H, S-H, N-H e O-H que absorvem frequências na faixa de 4.000-14.000 cm -1 .…”

A Rapid 1H NMR-Based Estimation of PONA for Light and Narrow Cut Naphtha Samples of Refinery Streams toward BS-VI Gasoline

“…The estimation of PONA by fluorescent indicator adsorption (FIA) [ASTM D1319-15] is another routinely used method. However, as discussed in our recent publication, 8 these methods lack generality and are not optimized for high throughput of samples during process optimization. This method is now obsolete due to non-availability of indicators.…”