Green River Kerogen Product Distribution Analysis: The Influence of Pyrolysis and Catalytic Reactions with Hydrogen-Donor Solvent
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The increase in global energy consumption of petroleum, which is estimated to even surge to ca. 37% by 2035, requires substitutes from other unconventional sources of oil and gas. Utilization of oil shale by technology and research enhancement on the upgrading process creates the opportunity to understand the role of unconventional oil and gas among the energy sources in the world. In this thesis, oil shale from Green River Formation in USA has been studies throughout the entire study. An enhancement of the product quality from decomposition of oil shale that is free for bitumen and carbonates has been investigated. Soxhlet extraction and decarbonisation of the oil shale have been performed for separation of bitumen and removal of carbonates in order to obtain bitumen- and carbonate free oil shale, called decarbonated kerogen. Characterization of oil shale and decarbonated kerogen has been conducted with TGA/DCS-MS, PY-GC/MS, BET and SEM in order to study mass loss of organic material during heating, solid conversion and product distribution from pyrolysis, and physical properties that may influence the decomposition. The effects of hydrogen-donor solvents and catalysts on product quality from pyrolysis of decarbonated kerogen have also been studied by characterization with TGA/DCS-MS, PY-GC/MS, SEM and XRF of products from liquefaction reactions. The hydrogen donor solvents studied includes tetralin, decalin and 2-propanol, whereas nickel and copper constitutes the investigated catalysts. The total organic matter content in decarbonated kerogen proved to be 45.29% and possible oil yield from oil shale was 85.14. The average apparent activation energies with pre-exponential factors for oil shale and decarbonated kerogen were respectively 118 kJ/mol and 1.97e+16 sec-1 for oil shale, and 113.9 kJ/mol and 1.56e+19 sec-1 for decarbonated kerogen. The kinetic factors from thermal study of decarbonated kerogen with tetralin, decalin and 2-propanol were respectively 89.33 kJ/mol and 1.36e+21 sec-1, 98.4 kJ/mol and 4.17e+16 sec-1 and 86.97 KJ/mol and 4.47e+24 sec-1. EGA of oil shale and decarbonated kerogen showed that maximum decomposition rate appears at 460 °C. Pyrolysis of oil shale and decarbonated kerogen provided a higher proportion of olefins relative to paraffins of respectively 57.6% from oil shale and 48.5% from decarbonated kerogen. Pyrolysis of decarbonated kerogen with hydrogen-donor solvents provided the highest share of paraffins of ca. 48% with a pyrolysis temperature of 460 °C. The solid conversion from the liquefaction reactions increased with higher reaction temperature, and the highest conversion was obtained from reaction with decarbonated kerogen and tetralin at 400 °C of approximately 84.8%. The samples without catalyst obtained in general highest solid conversion except from the samples with 2-propanol, in which reactions with Cu2+ provided the greatest extent of conversion of 87.5%. The study of reaction time did not show any clear effect on solid conversion for the reactions with decarbonated kerogen, Ni2+ and 2-propanol. The 1 hour reaction had the highest conversion of 50.8\% and the 36 hours reaction had a conversion of 32.7%. The reaction of solely decarbonated kerogen proved increased solid conversion from 57 to 81% with increased reaction time from 12 to 24 hours. The product distribution analysis showed that reaction of exclusively decarbonated kerogen provided a very high share of paraffins, 93.2%. Reactions with tetralin resulted in highest proportion of paraffins when Cu2+ was supplied, of 71.5%. Decarbonated kerogen and decalin in reaction obtained a percentage paraffins of 96.2%. For the samples with 2-propanol did Cu2+ show a positive impact on the paraffin percentage, respectively 95.6%. Analyses with SEM/EDX showed that the proportion of catalyst in the solid sample from reaction with 2-propanol was approximately 8%. For the reaction with tetralin, a catalyst amount of 10% was detected.