Catalytic Effects of Montmorillonite on Coke Formation during Thermal Conversion of Heavy Oil

Abstract

In situ combustion is an enhanced method to recover heavy oil. The formation and oxidation of coke are crucial to promote the combustion front. Heavy oil from China and montmorillonite, a major type of clay, were used as samples in this study. The thermogravimetric analyzer (TGA) was applied to temperature-programmed oxidation/pyrolysis experiments to study the effect of montmorillonite on the thermal conversion characteristics of heavy oil. A fixed-bed reactor was then used to obtain coke and study the effect of montmorillonite on coke properties. The characteristic temperatures of thermal conversion decreased with montmorillonite in the oxidizing atmosphere but remained unaffected in the pyrolysis atmosphere. The fuel deposition increased in both atmospheres because of montmorillonite's strong adsorption. In the oxidizing atmosphere, the presence of montmorillonite obviously promoted the progress of coke formation and increased coke yield. The content of O was increased, and the contents of C and H were decreased in coke. The oxidation activity of coke was improved, while trailing occurred due to the blocking in the pore structures of the montmorillonite skeleton. In the pyrolysis atmosphere, the presence of montmorillonite did not influence the coke formation temperature but increased the coke yield. The content of C was increased and the contents of H and O were decreased in coke. Coke oxidation activity was reduced with the more serious trailing phenomenon. Montmorillonite significantly affected coke formation through its strong adsorption to polar components in heavy oil in both atmospheres and obvious catalysis on dehydrogenation as an acid catalyst in the pyrolysis atmosphere, while it enhanced the oxygenation due to its large surface area and catalyzed polycondensation in the oxidizing atmosphere.

Oil-Dispersed α-Fe2O3 Nanoparticles as a Catalyst for Improving Heavy Oil Oxidation

“…3 ISC is the oldest member of the ThEOR family, and its effectiveness for heavy oil recovery has been proved by many economically successful field applications since the 1920s. 4,5 It is basically an air injection process into reservoirs to in situ create a combustion front to push oil to move to producers through multiple displacement of steam drive, distillation, flue gas flood, hot and cold water drive, and so forth. 6−8 In comparison to other ThEOR processes, ISC has many unique assets including the following: high thermal efficiency because of the in situ generation of heat, the most readily available and low-cost injectant (air) regardless of the reservoir location, applicability for a variety of reservoir settings (light and heavy oils and shallow and deep reservoirs), high recovery efficiency benefiting from many combined displacement mechanisms, and so forth.…”

“…The ISC technique has been given much attention recently for heavy oil recovery . ISC is the oldest member of the ThEOR family, and its effectiveness for heavy oil recovery has been proved by many economically successful field applications since the 1920s. , It is basically an air injection process into reservoirs to in situ create a combustion front to push oil to move to producers through multiple displacement of steam drive, distillation, flue gas flood, hot and cold water drive, and so forth. − …”

A Critical Review of Reservoir Simulation Applications in Key Thermal Recovery Processes: Lessons, Opportunities, and Challenges

“…It was found that the coke deposition in pores turned large pores into micropores which deteriorated permeability. A series of experiments were conducted to understand coke formation under different reaction conditions , and the presence of montmorillonites and nanoparticles . Yu et al in 2017 concluded that clay could accelerate reaction rates and improve an ignition process .…”

Coke Yield Prediction Model for Pyrolysis and Oxidation Processes of Low-Asphaltene Heavy Oil

“…Because the heavy oil coking process includes many serial and parallel reactions, the coking characteristics of heavy oil are complex. The coke yield from heavy oil is influenced by the coking temperature, oxygen concentration, heating rate, pressure, and so forth. ,, Meanwhile, the coke yield and reaction kinetics of coking reactions differ with different heavy oils. , Therefore, to systematically predict the influence of various conditions on heavy oil coking, it is necessary to establish an appropriate coke formation model.…”