Release of Bound Biomarkers Using Microscale Sealed Vessel Catalytic Hydrogenation

Abstract

The covalently bound biomarkers in the macrostructure of kerogen or asphaltene can provide unique information compared with the routinely extractable biomarkers. Here, a shale sample (immature Posidonia Shale) and an oil sample (Norwegian Geochemical Standard NSO-1) were systematically investigated by heating them to different temperatures and by mixing them with different catalytic materials to optimize the microscale sealed vessel catalytic hydrogenation (MSSV-Hy) protocol. It can be demonstrated that (1) tetralin acts as an effective hydrogen donor to stabilize the generated free radicals in the pyrolysis system enabling the bound biomarkers to resemble more closely their free counterparts, (2) PtO2 is the most appropriate catalyst for promoting the overall release of bound biomarkers, and (3) 390 °C is the best end temperature (from 200 °C at 0.7 °C/min) for the MSSV-Hy approach, balancing between bound biomarker yields and the protection of the original biomarker steric configurations. MSSV-Hy is a quick, highly reproducible, less sample demanding, and cost-effective method to release bound biomarkers and has great potential for studying the carbon cycle in its broadest sense.