Insight into the kinetic analysis of catalytic combustion for biomass after alkaline metals loaded pretreatment

•AM content affected the catalytic combustion process both at the pyrolysis process, more notably, the oxidization process.•During pyrolysis process, the activity energy decreased with AM loading pretreatment, and decreased with the increasing of AM content; For oxidization process, the oxidizing rate increased with AM loading pretreatment, and increased with the increasing of AM content.•The kinetic model described the catalytic combustion for biomass after AM loaded pretreatment was established.•The evolution of pyrolysis rate subordinated to the normal distribution model; The oxidization rates of acid-washing biomass followed the first order homogeneous reaction model; The oxidization rates of biomass-AM samples accorded well with RPM.

Biomass combustion was important for a wide range of scientific and industrial processes, and played a key role in biomass utilization. This study was aimed to research the catalytic combustion kinetics of biomass after alkali metals (AM) loaded pretreatment. Firstly, this paper investigated the behavior of catalytic combustion for biomass after AM loaded pretreatment. Without considering the evaporation of moisture, the thermal events of catalytic combustion for biomass could be divided into two mass loss steps. The first process was the loss of volatile compounds and the formation of semi-coke. The second process was volatile compounds and the semi-coke were oxidized, and released a lot of heat. Secondly, this paper evaluated the performance of catalytic combustion for different kinds of AM. With the increment of AM loading ratio, the initial pyrolysis temperatures reduced, whereas the devolatilization index, the comprehensive combustibility index, the semi-coke yield index and the differential thermal peak area showed an opposite variation trend. Additionally, at the same concentration, the same kind of AM had different catalytic influences on various type of biomass. Thirdly, this paper established the kinetic model to described the catalytic combustion for biomass after AM loaded, which accurately described catalytic combustion for biomass after AM loaded.