Effects of preparation parameters on the textural features of a granular zeolite/activated carbon composite material synthesized from elutrilithe and pitch

A granular composite material containing zeolite and activated carbon was prepared from elutrilithe and pitch powder. The process consisted of the following steps: pyrolysis of pre-shaped raw material, carbon dioxide activation, and subsequent hydrothermal transformation of aluminosilicate in alkaline solution. The resulting material exhibited hierarchical pore structure with high surface area and porosity as characterized by X-ray diffraction and nitrogen adsorption. The addition of pitch powder enhanced mechanical strength of the granular composite and adjusted zeolite-to-carbon ratio. Further, effects of preparation parameters on porosity of activated carbon and phase composition of zeolite were investigated. During carbon dioxide activation, porosity evolution resulted in the formation of new micropores in the carbon precursor and further enlarged original micropores; and the textural characteristics of activated carbon mainly depended on temperature and activation time. Zeolite with high crystallinity was obtained with appropriate alkalinity, temperature and hydrothermal synthesis time.