Researchers have previously developed quantitative 31P-NMR (Phosphorus Nuclear Magnetic Resonance) as an effective and efficient analysis method for the characterization of components with hydroxyl functional groups in bio-oils. The refinement and review of this method are required to transition it to a fully validated and industry-accepted quantitative analytical approach. This work documents steps taken towards that goal by determining sample processing delay limits, as well as the effects of high-water content and bio-oil complexity while working to establish the limits of detection and quantitation. Large-scale adoption of the method will increase the understanding of bio-oil characteristics, which is required for bio-oil upgrading and co-processing with petroleum feedstocks. By using NMR data in conjunction with gas chromatography – mass spectroscopy (GC-MS), it was determined that due to post-phosphitylation reactions, the reported population of reactive carboxylic acids is reduced over time – particularly in the case of short alkyl chained acids. Using a range of real matrices processed via popular conversion methods (e.g. thermos-catalytic reforming, fast pyrolysis, and hydrothermal liquefaction) and multiple prepared matrices, it was determined that the limits of detection and quantitation (LOD and LOQ) were negatively affected by moisture content and the complexity of the bio-oil sample. The limit ranges were determined as 0.05 - 0.1 mmol/g of bio-oil sample (LOD) and 0.14 - 0.34 mmol/g (LOQ). The results of this study further demonstrate the benefits of the method and support the need for a better understanding of the method’s chemistry and analytical limitations.

Determining sensitivity of 31P-NMR in the analysis of hydroxyl containing species in bio-oil products

ACS Fall 2020 Virtual Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.