Synthesis of mesoporous carbons by leaching out natural silica templates of rice husk

Abstract

Carbons with developed mesoporosity were obtained from rice husk (RH) according to a three step procedure, that includes carbonization in fluidized catalyst bed reactor at 450–600 °C or by pyrolysis in nitrogen atmosphere at 400–700 °C, and removal of mineral (silica) part due to interaction with equimolar mixture of K 2CO 3 and Na 2CO 3 at 750–1000 °C followed by washing out of soluble K and Na silicates. The obtained carbons have specific surface area ( A BET) up to 1676 m 2 g −1, and total pore volume up to 1.54 ml g −1, more than 80% of which are mesopores. The structure and morphology of the carbons were characterized by N 2 adsorption (77 K), XRD and TEM. The influence of the synthetic parameters such as temperature of the thermal treatment, composition of blends with carbonates was investigated. The main approach was that the SiO 2 of RH appears to be able to play a template role for the preparing carbonaceous materials. Thus it seems possible to control the textural properties of preparing carbons via affecting on the SiO 2 template properties by preparation conditions. The carbons are intended to be used as catalyst supports and adsorbents.