Preparation and decarburization characteristics of SiO2-Al2O3 composite aerogel modified by potassium carbonate

Abstract

In this paper, the preparation of potassium carbonate modified SiO2-Al2O3 composite aerogel, the carbonation characteristics of K2CO3 and the decarburization characteristics of regeneration cycle were studied. The influence of loading rate on CO2 adsorption was studied by using a fixed bed reactor, and the microstructure of the samples was analyzed by combining SEM and BET. The results show that during the alkali fusion sintering of Na2CO3, the Si-O-Si and Si-O-Al bonds break, the crystal structure is destroyed, and the covalent bond of mullite is transformed into the ionic bond of nepheline. Through orthogonal test, taking the specific surface area of aerogel as the measurement index, the optimal calcination conditions are determined as follows: 900 ℃, reaction for 60 min, Na2CO3 addition ratio of 0.5. The more K2CO3 is loaded, the less the corresponding active sites on the surface of the carrier. When the loading is 30%, the maximum CO2 adsorption capacity is 2.86 mmol·g–1. Excess K2CO3 will plug the pore structure, destroy the diffusion of CO2, and reduce the diffusion and utilization efficiency. The percentage of mesoporous pore volume decreased from 94.21% to 89.32%, indicating that the active component K2CO3 was mainly filled in the mesoporous. After 10 cycle regeneration tests, the CO2 adsorption capacity of the adsorbent decreased by 10.49%. The pore structure of the adsorbent was stable and the decarburization performance was excellent.