Molecular beam methods to study real time product chemistry: triglyceride thermal cracking

The pyrolysis product chemistry of triglycerides (TGs) is not well understood, but has important implications for renewable fuel production. In a somewhat modified molecular beam methodology, soft laser photoionization spectroscopies now are used to identify numerous products that can appear in time, rather than to study any particular one. Pyrolysis products are analyzed in real time after they are entrained in He gas expansions. Experiments proceed by recording time-of-flight mass spectra (TOFMS), using both 118 nm and 266 nm photoionization, as a function of increasing temperature of the TG sample. Correlations in the growth/diminution of various product mass peaks can be clarified by applying multivariate analysis calculations to the entire experimental set of TOFMS. New observations have emerged using the foregoing methods--results not seen in past gas chromatographic analysis of collected terminal products. Rather large polycyclic aromatic hydrocarbons (PAHs), up to 444 amu, have been detected, at non-trivial relative product fractions. Indeed, a small number of PAHs with MW ≥ 276 amu increasingly dominate the aromatics product distribution. Furthermore, PAH production begins at surprisingly low temperatures, as low as ~260 C.