Pyrolysis kinetics and pore-forming mechanism of hydrotalcite/carbon composite

摘要

A high-surface-area mixed-metal oxide (MgAlO-C) with interconnected mesopore networks was prepared by calcining the MgAl hydrotalcite/carbon (LDH/C) composite precursor at 500 degrees C, being characterized by XRD, BET/BJH and TG/DTG. The results indicated that the specific surface area and pore volume of the MgAlO-C increased up to 285 m(2.)g(-1) and 0.79 cm(3).g(-1), respectively. The thermal decomposition kinetics and pore forming mechanism of the carbon from the LDH/C precursor were investigated using TG/DTG technique, founding that the thermal decomposition of the LDH/C proceeded in four individual stages. Among them, the stages II and III were relating to the formation of the interconnected mesopore networks mainly due to high degree of carbonization and dispersing of carbon into the lattice of the MgAlO-C at the stages II and III (380-510 degrees C). Activation energies estimated by model-free methods were different between the decomposition stages II, and III, suggesting that the dominant control mechanisms on carbon were disparate during the two stages. In situ generated carbon as a "co-generated template" was an essential factor to the formation of interconnected mesopore networks in the MgAlO-C.