13C Solid-State NMR Analysis of the Chemical Structure in Petroleum Coke during Idealized In Situ Combustion Conditions

Petroleum cokes with different chemical structures and oxygen-containing functional groups were obtained from two kinds of naphthenic- and paraffin-base crude oils by simulating an in situ combustion (ISC) process with the same reaction atmosphere and different reaction temperatures. C-13 wide-cavity solid-state nuclear magnetic resonance (C-13 NMR) spectroscopy was used to identify and investigate the oxygen-containing functional groups of petroleum cokes obtained under different compositions and reaction temperatures. This study demonstrated that with the increase of coking temperature, the content of alkyl side chain and active oxygen-containing functional groups in naphthenic-base crude coke decreased obviously, while the content of aromatic carbon increased. The C-13 NMR analysis of the two kinds of petroleum cokes obtained at 500 degrees C further revealed that the paraffin-base petroleum coke retained a high content of oxygen- and nitrogen-rich functional groups, while the naphthenic-base petroleum coke had a lower amount of carbonyl groups and oxygen-containing functional groups.

Automated summary

As the coking temperature increases, the content of alkyl side chains and active oxygen-containing functional groups in naphthenic-base crude coke decreases significantly, while the content of aromatic carbon increases.