A new in-situ pyrolytic time-of-flight mass spectrometer instrument for study on coal pyrolysis

• An in-situ pyrolytic time-of-flight mass spectrometers was built to study coal pyrolysis. The character of this method is in-situ, time-resolved, fragment free and high sensitive.
• By the fragment-free mass spectra and temperature-products profile, the structure difference in macromolecules of different coal was discussed.
• We observe that coals with bigger aromatic rings and longer side chains would decompose in relative low temperature.

This paper reports a novel in-situ pyrolytic time-of-flight mass spectrometers which is applied on coal pyrolysis studies. The pyrolytic products of Zhundong (ZD), Xilinguole (XLGL) and Shenhua (SH) coals were investigated using both electron ionization (EI) and vacuum ultraviolet photon ionization (VIV-PI) method. The evolutions of H2O, CO2, CO, CH4 and H2 from pyrolysis of these three coals were analyzed using electron ionization. The qualitative and quantitive performance of our device was discussed by comparing DTG data and ion current curve which was gathered from mass-spectrum. The distribution and evolution of the organic products during pyrolysis were investigated using PI. We found that 1 or 2 ring aromatic compounds were dominant pyrolytic products of the three coals, while some olefin and alkynes products were also observed. Through analyzing the distribution and evolution behavior of organic pyrolytic products, the differences in macromolecular structures of those coals and its influence on pyrolytic process was discussed. The condensation of olefin during coal pyrolytic process was also observed. This work demonstrates the good performance of our in-situ pyrolytic time of flight mass spectrometer on studying of coal pyrolysis.