CHAPTER 6: Development and Use of Catalytic Hydropyrolysis (HyPy) as an Analytical Tool for Organic Geochemical Applications

Continuous-flow pyrolysis conducted at high hydrogen gas pressures (typically 15 MPa) and with a suitable catalyst (termed catalytic hydropyrolysis or HyPy) was first used as a means to produce liquid products in high yields from solid fossil fuels. It was later realised that HyPy could be harnessed to function as an analytical technique for a variety of organic geochemical applications involving the fragmentation of geomacromolecules or functionalised lipids, and the release of diagnostic lipid biomarker structures. HyPy possesses the unique ability to produce high yields of hydrocarbon biomarkers from source rock kerogens, recent sediments, and petroleum asphaltenes, while minimising structural alteration by isomerisation andcracking. This has enabled the technique to be used in petroleum geochemistry for important applications where conventional biomarkers fail:for example, for characterising heavily biodegraded oils, samples contaminated by oil-based drilling mud, or oil field solids such as tar mats/pyrobitumens, and for deciphering basin filling history of migrated petroleum fluids. HyPy hasalso gained prominence in geobiologicalstudies related to ancient biomarker detection informing the evolution of microbial and animal life across Earth's history. The technique has expanded the lipid biomarker toolbox via the screening of extant microbial cultures and sponges to quickly elucidate the relative abundance and variety of lipid biomarker hydrocarbon skeletons that they biosynthesise. HyPy has also been used for the detailed characterisation of the insoluble macromolecular material in carbonaceous chondrite meteorites. In addition, HyPy has recently been applied as a reductive method for the isolation and quantification of black carbon in soils, coals, and charcoals.