Preparation of silica supported nanoscale zero valence iron and its feasibility in viscosity reduction of heavy oil

Conventional solvent and thermal enhanced oil recovery techniques are less competitive, because of the presence of resin and asphaltene components which are difficult to remove; therefore it is imperative to develop new types of catalysts for the efficient recovery of heavy oil. In this reported research, silica-supported nanoscale zero valence iron (denoted as SiO₂/nanoFe) is adopted as a catalyst to break the C-S bonds of resin and asphaltenes so as to reduce the viscosity of heavy oils and acquire enhanced oil recovery. A target SiO₂/nanoFe catalyst was prepared via liquid-phase reduction of ferric chloride hexahydrate by sodium borohydride in the presence of surface-modified silica as a support. The as-prepared SiO₂/nanoFe catalyst was characterised by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectrometry. The dispersibility of as-prepared SiO₂/nanoFe catalyst in various organic solvents was evaluated, and its specific surface area was determined using classic Brunauer-Emmett-Teller isotherm method. Moreover, the catalytic performance of the SiO₂/nanoFe catalyst for the aquathermolysis process of a heavy oil sample collected from Shengli Oilfield (Dongying, China) was evaluated. It was found that as-prepared SiO₂/nanoFe, composed of silica with an average size of about 10 nm and zero valence iron nanoparticles with an average size of several nanometers, exhibits good anti-oxidation stability. The SiO₂/nanoFe catalyst also exhibits good catalytic performance for the aquathermolysis process of heavy oils; in particular, at a mass fraction of 1.0%, it can significantly reduce the viscosity of a tested heavy oil from 184 to 42 Pa·s, showing promising potential in the industrial production of heavy oils.