Effect of decalin as hydrogen-donor for in-situ upgrading of heavy crude oil in presence of nickel-based catalyst

Abstract

The effect of decalin as hydrogen-donor on the catalytic and non-catalytic hydrothermal upgrading of heavy crude oil was studied. The donating (dehydrogenation) capacity and conversion of decalin in presence of nickel-based catalyst (nickel (II) stearate) were evaluated. In addition, the changes in composition of dehydrogenated products, release and consumption of hydrogen during decalin dehydrogenation in presence and absence of Ni-stearate and heavy crude oil were studied. All of the upgrading and dehydrogenation experiments were carried out at 300 °C, 72 bar (1044.27 psi) and 24 h of reaction time. The upgrading of heavy crude oil in presence of decalin and Ni-stearate exhibited a good performance for conversion of decalin as well as for promoting the in-situ upgrading of heavy crude oil. The maximum decalin conversion level was found to be 21.95% in the presence heavy crude oil, water and nickel stearate. Ni-stearate was mainly in-situ transformed into particles of NiO and Ni3S2, which took the role of active phases for catalyzing the dehydrogenation of decalin and promoting heavy crude oil upgrading. The use of decalin as a hydrogen-donor together with catalyst resulted in high viscosity reduction (69.2%), increase of saturates content (especially low molecule weight alkanes C10-C20), decrease of resins and asphaltenes content, and removal of sulfur and nitrogen.