PETR 44 |
| Total acid number (TAN) and its distributed properties (distribution of TAN as function of boiling point) are important assay measurements that impact refinery optimization, corrosion management and safe refining of high TAN crudes. The measurements of distributed properties are inherently time consuming due to the requirement of physical distillation followed by assay measurement (titration). In addition, measurement of high boiling cuts cannot be made accurately due to the thermal decomposition of naphthenic acids. Here we report a new technology for the measurement of TAN and its boiling point distribution without physically distilling the sample. The technology is termed as "Electrospray TAN or E-TAN" as it is based on Electrospray ionization mass spectrometry (ESI-MS). A chip-based nano-electrospray system enabled micro-scale (<200 mg) and high throughput (20 samples/hr) measurement. Under negative ion conditions, ESI-MS selectively ionizes and detects acidic compounds (naphthenic acids, phenols and non-basic nitrogen compounds) in petroleum samples. Acid and nitrogen molecules can be differentiated by the odd-even mass rules. Phenols and acids can be resolved by their carbon number distributions. A mass-dependent collision-induced dissociation technique was developed to eliminate dimer formation while minimizing the fragmentation of low molecular weight acids in the ESI process. This feature is key to obtain correct molecular weight distribution of naphthenic acids.
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Symposium Honoring Martin Gorbaty
8:20 AM-11:55 AM, Monday, August 20, 2007 Boston Park Plaza -- Plaza Ballroom, Oral
Division of Petroleum Chemistry |