Understanding the hydrothermal, thermal, mechanical and hydrolytic stability of mesoporous KIT-6: A comprehensive study

Abstract

The three dimensional KIT-6 with interconnected mesoporous was synthesized using triblock copolymer (P123) in mild acidic condition. The hydrothermal, thermal, mechanical and hydrolytic stability of KIT-6 were comprehensively investigated by N2 adsorption/desorption, small-angle X-ray scattering and electron micrograph. In the initial stage of synthesis, washing of as-synthesized KIT-6 with water improves the textural property such as surface area and pore volume. The size of primary mesopores and pore volume of the material could be tailored by ageing the solution without any loss in structural morphology. KIT-6 shows the high mechanical stability up-to 4680 bar and preserves its mesopore surface area possibly due to the presence of thicker pore wall and cubical structure. KIT-6 shows the gradual decrease in surface area, pore volume and diameter with increasing calcination temperature from 823 to 1173 K, due to sintering/shrinkage of silica structure. It also shows the stable structural properties even after ageing for 6 months in atmospheric conditions and 1 month in water at room temperature. However, after 3 days of ageing in boiling water, KIT-6 still retains its porosity. In presence of ultra-high pressure, CO2 shows good surface interaction towards KIT-6 with sorption capacity of 1.42 mol/kg (1 bar) and 10.1 mol/kg (20 bar) at 273 K without significant damage to its structure. Additionally, it also shows 2.38 wt% H2 storage capacity at 30 bar and 77 K. The highly stable KIT-6 is considered to be a good material for catalyst support, nano structure, CO2 separation and H2 storage.