Insight into a stepped fragmentation of coal-related model compounds using a tandem Orbitrap mass spectrometer

Abstract

To provide basic knowledge for coal conversion, twenty one coal-related model compounds (MCs) were analyzed using a tandem Orbitrap mass spectrometer (MS). Higher-energy collisional dissociation (HCD), a method of Orbitrap MS, unraveled the detailed fragmentation pathways and de-alkylation behaviors of the ionized MCs under collision energies from 10 to 80 eV. Chemical bond breaking, hydrogen loss, rearrangement reaction, and elimination of neutral fragments were discussed to elucidate clear fragmentation pathways. For arenes without alkyl chains, a higher energy threshold of fragmentation was observed with the increasing of aromatic ring due to a higher conjugate effect of condensed aromatic structure. The existence of alkyl chains decreased the threshold of fragmentation because of the electron-donating effect of alkyl chains. Heteroatom-containing aromatic compounds, a series of important species in coal, showed a diversified fragmentation patterns due to a low bond dissociation energy and a weak conjugate effect compared with arenes. Fragmentation pathways and de-alkylation behaviors of coal-related MCs will contribute to building monitoring methods for coal and its derivatives conversions in chemical industry.