Petrochemical Application of Low Field Benchtop NMR: Characterization of Polyols and Epoxy Resins

Importance of the Topic

The petrochemical industry relies on precise analysis of derivatives such as polyether polyols and epoxy resins to optimize material properties and ensure product quality. Low-field benchtop NMR enables rapid, cost-effective structural and quantitative characterization directly in the laboratory, facilitating process control and reducing dependence on centralized high-field facilities.

Objectives and Study Overview

This work demonstrates the application of benchtop NMR spectrometers to three petrochemical derivative analyses:

• Quantification of ethylene oxide (EO) content in polyether polyols
• QA/QC assessment of epoxy resin batches
• Determination of ethanol content in E10 gasoline blends

Results highlight the versatility and practicality of compact NMR instruments for routine petrochemical analysis.

Methodology and Instrumentation

Proton NMR exploits distinct chemical shift regions of polymer repeating units for composition analysis. For polyols, methyl resonances (0.6–1.6 ppm) and methylene/methine resonances (2.8–4.0 ppm) are integrated and inserted into the ASTM D4875-11 formula to calculate weight-percent EO. Epoxy resins are characterized by comparing experimental spectra to predicted Mnova® models to verify epoxide functionality. Gasoline blends are analyzed by identifying ethanol peaks in complex hydrocarbon spectra.

Main Results and Discussion

• Polyol EO Content: The picoSpin 80 (80 MHz) resolved key EO and PO resonances, enabling accurate EO quantification in unknown samples consistent with vendor specifications.
• Epoxy Resin QA/QC: The picoSpin 80 spectrum allowed clear identification of epoxide signals and batch consistency assessment relative to a Bruker AMX 300 reference and Mnova simulations.
• Gasoline Blend Analysis: The picoSpin 45 (45 MHz) spectrum of E10 gasoline displayed distinct ethanol resonances, facilitating rapid estimation of ethanol fraction in a complex hydrocarbon matrix.

Benefits and Practical Applications

• Fast, in-house NMR measurements without the need for high-field infrastructure
• Streamlined QA/QC workflows and reduced sample turnaround times
• Cost-effective solution for routine polymer and fuel quality control

Future Trends and Applications

• On-line integration of benchtop NMR for real-time process monitoring in petrochemical plants
• Expansion to additional derivatives such as lubricants, plasticizers, and bio-based monomers
• Advanced chemometric software and spectral databases for automated interpretation and predictive modeling

Conclusion

Benchtop low-field NMR provides a powerful combination of accessibility, speed, and analytical capability for petrochemical derivatives. It supports accurate quantification and structural analysis of polyols, epoxy resins, and fuel blends, enhancing product development and quality assurance in chemical manufacturing.

Instrumentation

• Thermo Scientific picoSpin 80 MHz 1H NMR spectrometer
• Thermo Scientific picoSpin 45 MHz 1H NMR spectrometer
• Bruker AMX 300 MHz 1H NMR spectrometer (reference data)
• Mestrelab Research Mnova software for spectrum prediction and processing

Reference

• ASTM International. ASTM D4875-11 Standard Test Method for Determination of Ethylene Oxide Content in Polyether Polyols by Proton Nuclear Magnetic Resonance (1H NMR). 2011. DOI:10.1520/D4875-11
• Hammond CE, Kubick DK. Proton NMR Characterization of Polyether Polyols. Journal of the American Oil Chemists' Society. 1994;71(2):113–115.