Thermo-Catalytic Destruction of Kerogen in the Presence of Cobalt Oxide Nanoparticles and Mineral Pyrite
Authors: Onishchenko Yaroslav , Vakhin Alexey , Voronina Elena , Nurgaliev Danis 
Published: October 2016

The investigation of the process of the kerogen in situ catalytic transformation accompanied by the synthetic oil production. To develop kerogen-rich deposits, such technologies as in situ combustion and retorting, presupposing productive layers warming-up, can be employed. The intensification of the light hydrocarbon generation under the kerogen cracking is achieved while using nanodimensional catalysts based on the transition metals. The cracking catalyst on the cobalt basis alongside with the impact on the organic substance can promote to the transformation of pyrite into mixed iron oxides, the latter also being the catalysts of the processes under discussion.

Laboratory modeling of the thermo-catalytic effect on the kerogen samples of Bazhenov Shale has been carried out. Before separation kerogen from the rock sample, bitumenoids were extracted by means of chloroform. Kerogen was separated by step-by-step dissolution of minerals with hydrochloric and hydrofluoric acids. Pyrite associated with kerogen was not separated in order to preserve the native structure and composition of the organic substance. Thermo-catalytic effect conditions and the dosing of the catalyst on the cobalt basis were varied. To study the kerogen transformations and the synthetic oil properties the following methods such as the solid-state NMR allowing us to determine the relative content of the functional groups, CHNS/O analysis of the composition by means of combustion method, microelement analysis, X-ray structural analysis, Mossbauer spectroscopy, SARA analysis, and IR-spectroscopy were used.

Comparison of the solid-state NMR results of the examination of the initial kerogen and the kerogen after the thermo-catalytic treatment demonstrates significant compositions changes. The aliphatic hydrocarbon content decreases due to the cracking of the aliphatic substituents and the aromatic skeleton condenses. As this takes place, the mobile hydrocarbons are squeezed out from kerogen. A catalyst can be used as the precursor from which the active forms is formed under the elevated temperature or as the stable suspension of nanodimensional particles in aqueous or organic media.

According to the data of the X-ray structural analysis, it has been determined that, as a result of the thermo-catalytic treatment, a part of monomineral pyrite transfers to the magnetic form, namely, magnetite. The results of the Mossbauer spectroscopy show the decrease in the pyrite partial area. The main components in the spectrum demonstrate the super-line magnetic structure consistent with the non-equivalent positions of iron cations with in the spinel Fe3O4 structure.

Thus a manner, under the thermo-catalytic effect on the kerogen-containing rocks the processes of the destructive hydrogenation with formation of liquid hydrocarbons take place. The processes above are quite catalytic, accompanied by the hydrocarbons molecules activation with power and chemical methods. Iron-containing minerals of all other ones found in the thermal transformation of kerogen. Pyrite under thermal treatment transforms into hematite which is a hydrocracking process. The influence of the nanodimensional catalyst based on cobalt aims at the organic substance cracking and the activation of pyrite transformation. The degree of pyrite transformation directly depends upon the treatment conditions and the presence of the catalyst. The phenomenon of the double action of the catalysts based on cobalt within the framework of the processes of the organic substance transformation on the example of the kerogen-containing rock samples of Bazhenov Shale has been discovered found. The catalyst can be used as a precursor from which the active forms or as a stable suspension of the nanodimensional particles. Alongside the kerogen cracking, the transformation of mineral pyrite to mixed iron oxides, that in their turn, are also cracking catalysts, intensifies significantly, which increases the synthetic oil productive capacity. To determine the mechanisms of the in situ kerogen transformation is necessary when creating the technologies of the kerogen-rich deposits development.