Preparation of caking components of coal using [N4441][Cl] thermal treatment and alkylation reaction

• A novel method to artificially synthesize caking components was proposed. • Caking components were successfully prepared by [N 4441 ][Cl] treatment and alkylation. • Alkylation at 190 °C maximizes caking index via side-chain introduction. • Polycyclic aromatic and long-chain aliphatic structures are caking components. A method was devised to prepare the caking components of coal from Shenhua long-flame coal (SH) using an ionic liquid [N 4441 ][Cl] thermal treatment, followed by a β -molecular sieve-catalyzed alkylation reaction to introduce alkyl side chains. A series of characterizations were used to elucidate the mechanism by which the alkylation reaction enhances the caking property of the extract. The results showed that the caking index of the extract alkylated at 190 °C (IL N -extract-A 190 ) was the highest among all samples. From the Fourier transform infrared and thermogravimetric data, alkyl side chains had been successfully incorporated into the aromatic rings of the extract. The pyrolysis–gas chromatography-mass spectrometric analysis showed that IL N -extract-A 190 contained abundant polycyclic aromatic and long-chain aliphatic structures. The excellent caking property of IL N -extract-A 190 arises from its high content of polycyclic aromatic and long-chain aliphatic structures, especially the abundant alkyl side chains introduced by the alkylation reaction. This study can provide an in-depth understanding of the caking components of coal, thereby improving the utilization efficiency of coking coal.