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Polyalphaolefin Hydrogenation – Residual Olefin Analysis – 1H NMR versus Bromine Number

by Benchtop NMR, NMR, PAT, Petroleum, Process NMR, qNMR, Reaction Monitoring

1H NMR is an excellent tool for monitoring the residual olefin content of polymers after hydrogenation reactions. The fact that the olefin fall in a unique region of the spectrum means that it is a straightforward measurement to quantify the %H present as olefin or to correlate that olefin content with other analyses such as bromine number. Here is an example of a polyalphaolefin residual olefin analysis. The olefin proton content (%H) was plotted against bromine number values obtained on each of the samples. A linear correlation was obtain but two different correlations were observed that were dependent on the viscosity index of the polyalphaolefin being analyzed. Figure 1 shows the 1H NMR spectra obtained on neat samples on a Picospin-80 spectrometer operating at 82.3 MHz. The methyl and methlene protons of the polymer backbone are plainly seen and the olefin and alpha-olefin protons are observed.

1H NMR - Polyalphaolefins - Residual Olefin Analysis
Figure 1: 1H NMR – Polyalphaolefins – Residual Olefin Analysis

 

Figure 2 shows the linear correlation between %H olefin and bromine number with the two correlations caused by different VI grade being indicated. The analysis shows that for the two viscosity grades the grade can be identified from the linear correlation that the data falls onto and the %H olefins content can directly yield the bromine number. This NMR method provides an alternative to the following ASTM standards:                                                            D1159 Test Method for Bromine Numbers of Petroleum Distillates and Commercial Aliphatic Olefins by Electrometric Titration                                      D1491 Test Method for Test for Bromine Index of Aromatic Hydrocarbons by Potentiometric Titration                                                                         D1492  Standard Test Method for Bromine Index of Aromatic Hydrocarbons by Coulometric Titration                                                                             D2710 Test Method for Bromine Index of Petroleum Hydrocarbons by Electrometric Titration                                                                                      D5776 Test Method for Bromine Index of Aromatic Hydrocarbons by Electrometric Titration

Correlation of Olefin Content obtained by 1H NMR with Bromine Number in Polyalphaolefins
Figure 2: Correlation of Olefin Content obtained by 1H NMR with Bromine Number in Polyalphaolefins

Residual Catalytic Cracker – Heavy Petroleum Feedstream Properties from 1H NMR at 43 MHz

by Benchtop NMR, Chemistry, Chemometrics, Energy, NMR, PAT, Petroleum, Process NMR, qNMR, Reaction Monitoring, TD-NMR Tagged: , ,

Back in October we presented a talk at Gulf Coast Conference that concerned the prediction of the chemical and physical properties of heavy petroleum feeds being converted to higher value product in a residual catalytic cracker (RCC). Over the years we have analyzed these materials by 300 and 60 MHz NMR and obtained good PLS-regression models that can adequately predict properties for real-time process control and optimization in a petroleum refinery. With the advent of a large number of new benchtop NMR systems we have been convincing ourselves that these types of analyses can be performed by systems such as the Magritek Spinsolve 43 MHz. We ran a series of samples that had been sitting around our lab for 15 years by dissolving them at about 50 volume% in a 50/50 CDCl3/CS2 solvent system. For each sample we had laboratory test data for a number of chemical and physical properties of interest to process engineers. We regressed the lab data variability against the variability in the Magritek 43MHz 1H NMR spectra and obtained cross-validated PLS models. The presentation material is given here at this link – Gulf Conference Presentation – 43 MHz RCC Feedstream Regression Models

From Atoms to Flavour: The Chemistry of Beer

by Beer, Chemistry, Chemometrics, NMR, Process NMR, qNMR, Reaction Monitoring Tagged: , , , , ,

Adam DiCaprio (ex PNA) gave an excellent Science Cafe Talk under the auspices of the ACS North Carolina Section at the Busy Bee Cafe in downtown Raleigh on December 2, 2014. CHanging gears from his previous talks he centered the discussion on malt and hop chemistry as well as an start-to-finish NMR analysis of production runs of a bottled commercial tavern ale. If you are interested in having Adam give a detailed chemistry seminar on beer at your section meetings please contact him directly at adam@process-nmr.com.

A PDF version of his talk is available here …. ACS Science Cafe Talk – Dicaprio – Busy Bee Cafe – Raleigh NC – 12-2-14

Presentations at SMASH 2014

by Beer, Chemistry, Chemometrics, Herbal Supplement, Process NMR, qNMR, Reaction Monitoring

“Beer Manufacturing and Analysis by NMR”, John C. Edwards and Adam Dicaprio, Presented at the Mestrelab MNova Users, Meeting – SMASH, Atlanta, GA, September 7, 2014
Get PDF Here

“Survey of Low Field NMR Spectrometer Platforms for Successful Screening of Sexual Enhancement and Weight Loss Supplements for Adulteration with Drugs and Drug Analogs”, John C. Edwards, Kristie Adams, Anton Bzhelyansky , Presented at SMASH Conference, Atlanta, GA, September 7-10, 2014.
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Special Issue on Benchtop NMR systems in Wiley Journal “Magnetic Resonance in Chemistry” – please consider submitting a technical or review paper

by Chemistry, Chemometrics, NMR, PAT, Process NMR, qNMR, Reaction Monitoring, TD-NMR

I was just asked by Roberto Gil (Carnegie Mellon) to pull together a special issue if Magnetic Resonance in Chemistry” on the topic of Benchtop NMR. I will personally be hitting up everyone I know who is working in this area to provide technical papers on their work in this area. I also wanted to extend an invitation to the members of this group to submit a paper for this special issue.

All topics will be considered but I would like to stay away from “traditional” 1H TD-NMR and restrict 1H TD-NMR applications to new approaches. On the high resolution side (45, 60, 80 MHz) I am hoping that applications with some real meat might be submitted rather than brochure type papers with just spectra of solvents and small molecules.

Please feel free to contact me directly if you have ideas on submissions. My contact information is listed below.

Sincerely,
—
John C. Edwards, Ph.D.
Manager, Process and Analytical NMR Services
Process NMR Associates, LLC
87A Sand Pit Rd, Danbury, CT 06810, USA
Tel: +1 (203) 744-5905 Cell: +1 (203) 241-0143
Skype: jcepna
e-mail: john@process-nmr.com