Investigation on the chemical structure evolution and action mechanism of coal during catalytic combustion.

Catalytic combustion is one of the most promising technologies to realize efficient and clean coal combustion, but its catalytic mechanism is unknown until now. This study selected three types coal to explore the influence of catalysts on the chemical structure, surface morphology, and action mechanism during combustion. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were characterized the surface chemical structure of combustion products. The results showed that the aliphatic hydrogen decreased and then increased, the content of –C O and aromaticity(I) increased, and the aromatic condensation (DOC) and C C content decreased by catalysts. Both FTIR and XPS results demonstrated that the catalysts were easy to promote the dehydrogenation condensation reaction between coal molecules, disrupting the stability of coal aromatic structure, thereby generating many free radicals and improving coal combustion. BET and scanning electron microscopy (SEM) were used to observe the effect of catalysts on the pore structure and surface morphology of combustion products. The results showed that the pore structure of product with catalysts continuously formed from micropores to medium pores and even large pores, which accelerated the oxygen transport and chemical reaction on coal surface. Finally, the mechanism of catalytic coal combustion was summarized. • The evolutionary behavior of products during catalytic combustion was investigated. • Catalysts may tend to act on -CH n and C C structures, thereby improving combustion. • Catalysts increased the contact between carbon and oxygen, making fully combustion. • The overall mechanism of catalytic coal combustion was proposed. [ABSTRACT FROM AUTHOR]