Modern industry strongly
relies on the molecular analysis of fossil
petroleum and petroleum-derived materials. In the context of a circular
economy and carbon neutrality, the chemical description of alternative
feedstock materials, such as waste plastic and biomass pyrolysis oils,
increases in importance. Moreover, online monitoring of the thermochemical
and catalytic conversion processes has gained rising attention. In
this framework, evolved gas analysis (EGA) concepts with soft photoionization
mass spectrometry (PIMS) were successfully deployed for numerous challenges.
On the one hand, photoionization is a highly versatile technique and
allows for “soft” ionization of the analyte molecule,
preserving the molecular information. On the other hand, multiple
evolved gas analysis concepts exist with unique benefits, such as
the mass loss information in thermogravimetry coupling, high-throughput
in direct inlet probe concepts, or straightforward reactor monitoring,
allowing for direct online insights into pyrolytic transformation
processes. Hence, this review aims to summarize the recent work in
the field of EGA–PIMS. After technical description of the multiple
photoionization and thermal analysis concepts, applied studies are
summarized, discussed, and evaluated. Besides fossil fuels, studies
on alternatives from renewable materials, such as biomass pyrolysis,
plastic pyrolysis oils, and recycling processes, are reviewed. Finally,
future perspectives on this field are given, highlighting the importance
of those soft ionization schemes together with state-of-the-art detection
by high-resolution mass spectrometry in the field of energy and fuels
research.