On the use of metallic nanoparticulated catalysts for in-situ oil upgrading

An exhaustive review on the application of different metal-based nanoparticles for the upgrading of heavy oils has been performed. Particular emphasis has been put on those catalysts used for in-situ upgrading using various thermal treatment methods aiming at extracting heavy oils in a more effective manner. Different types of catalysts have been identified, such as monometallic (Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ce, and W), non-supported bimetallic (Ti/Zr), non-supported polymetallic (various mixtures of Co, Mo, Ni, W, Al, Zn, Cu), and supported (various metals on silica, alumina, carbon, zeolite, biogenic particles, complex inorganic and organic). Due to the great diversity of nanoparticulated catalysts (type, metal content, synthesis procedure, particle size) and evaluation conditions (experimental setup, reaction conditions, type of feed), it is not possible to make a direct comparison on their performance. Some results are highlighted on the effectiveness of the catalysts for heavy oil upgrading in terms of asphaltene adsorption, viscosity reduction, increase of API gravity, and coke formation. The reviewed literature indicates the need for more research on this topic as to develop more effective catalysts not only for increasing the recovery factor but also for permanent upgrading of the quality of heavy and extra-heavy oil.