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In this work, the in-situ upgrading of heavy oil from Tatarstan oilfield using steam and copper stearate as a catalyst at 250 °C and 35 bar for 24 hours was studied in stainless-steel reactor. Changes in the density/API gravity, viscosity, chemical composition (SARA-analysis), elemental composition and structure (FTIR-spectroscopy) of heavy oil before and after conversion were determined. Generally, we can summarize, that the content of resins and asphaltenes as well as the average molecular weight of heavy oil were reduced after conversion process. Whereas, amount of saturated and aromatic hydrocarbons was increased due to the destruction of its high molecular weight components. Also, irreversible decrease of viscosity was fixed.

The Mossbauer parameters (the isomer shift δ, the quadrupole splitting ΔE, and the probability of recoilless absorption f') have been analysed for a large number (more than 200) of complexes of mono- and bi-dentate organophosphorus complexes with tetra-alkyltin and alkyltin halides. It is shown that the Mossbauer method can be used to determine the localisation centres of the donor–acceptor bond in complexes of organophosphorus compounds with tin tetrahalides and to determine the geometrical structures of the complexes. It has been observed that the quantities δ, ΔE, and f' for the compounds [R'R''R'''P(Y)]2(1)SnRnX4–n are definitely influenced by the nature of the substituents in the ligand and in the acceptor. This influence can be described with the aid of the reaction constants of the substituents σph and σ*. The bibliography includes 110 references.