Interactions of Oil Shale and Hydrogen-Rich Wastes during Co-pyrolysis: Co-pyrolysis of Oil Shale and Waste Tire

Co-pyrolysis of oil shale and waste tire could be an economical and environmental-friendly way to recover waste tire if it could improve the quality and quantity of pyrolytic shale oil. In this paper, a thermogravimetric system coupled with a mass spectrometry system (TG-MS) was applied to investigate pyrolytic behaviors of co-pyrolysis. It was found that co-pyrolysis had little effect on char formation; however, the MS system detected that co-pyrolysis boosted gaseous volatiles of a medium molecular weight as well as H2 and H radicals. Therefore, simulating cells were constructed to run reactive force filed molecular dynamics (ReaxFF MD) simulations, which aim to further investigate mechanisms of co-pyrolysis. In simulations, intermediate products were categorized into six classes according to the carbon number. Simulations indicated that co-pyrolysis had little effect on char mass fractions (40 ≤ C), which coincided with the TG findings. Meanwhile, co-pyrolysis favored the breakage of CC bonds and CO bonds within kerogen and thus resulted in more light shale oil with less heteroatom O. Specifically, a more light oil fraction (5 ≤ C ≤ 9) is the product of rearrangement reactions whose reactants are the gaseous intermediate (C < 5) from CC bond rupture. The heteroatom O from CO bond rupture is much more likely to transform into H2O.