Interactions of oil shale and hydrogen-rich wastes during co-pyrolysis: Improvements of oil quality

The "Carbon Peak and Carbon Neutrality" goal requires China actively explore new ways to supplement the oil supply for Chinese situation of oil shortage. Enormous oil shale reserves and large amount of waste plastics are viable feedstocks for supplementing the oil supply. However, individually pyrolyzing oil shale and waste plastic has its drawbacks, that is, the pyrolysis oil from oil shale contains more O and N heteroatoms and the pyrolysis oil from waste plastic has extremely long carbon chains, which both keep the pyrolysis oil from substituting crude oil. In this study, co-pyrolysis of oil shale and plastic (polypropylene, low-density polyethylene, waste tires) was used to produce oil. It could be found that the inorganic components in oil shale can promote the rupture of plastic, thereby reducing the heavy components in the oil (30 <= C < 40) and enhancing the light components (C < 30). Meanwhile, co-pyrolysis can effectively reduce the O and N components in the oil phase. The results of reactive force field molecular dynamics simulations showed that the reactive radicals formed by waste plastics first accelerate the pyrolysis reaction, promote the breakage of aliphatic chains in the oil shale kerogen. and thus, more intermediates, especially gas containing O (C<5), are going to form. Furthermore, intermediates (5 <= C) could interact with each other to form char. More O- and N-containing components will remain in the char, further reducing the O and N heteroatom content in the oil.