Partial oxidation of methane under conditions of adiabatic compression (review)

Abstract

Adiabatic compression of gases by a free piston is a method of gas–phase kinetics for studying thermal reactions without the influence of reactor walls. The article discusses the advantages and features of this method and its applicability in technological processes. In a historical context, the article presents the experimental results of partial oxidation of methane mixtures into synthesis gas and oxygen-containing organic substances obtained in an adiabatic compression reactor. The non-catalytic conversion of methane into synthesis gas has been investigated on a laboratory scale and tested on large installations (chemical compression reactors) and is recognized as promising for practical use. It is also shown that when using adiabatic compression, it is not possible to obtain practically significant yields of formaldehyde and methanol. It has been found that when compressing rich mixtures of methane, ignition occurs in a narrow range of compression degrees, and the degree of conversion of methane and oxygen increases dramatically. During adiabatic compression of model biogas mixtures, the effect of CO₂ additives on the partial oxidation of methane is considered. It has been established that the presence of CO₂ in the initial mixture leads to difficulty in ignition and a decrease in the degree of conversion of methane and oxygen. Three modes have been established for CO₂, depending on the degree of compression and, accordingly, on temperature: an increase in its content relative to the initial level during partial oxidation without ignition, an increase in its content upon ignition, and a decrease in its content upon ignition. It has been shown that synthesis gas with an H₂/CO ratio of ≈ 1 can be obtained by partial oxidation of biogas.