Synthesis of hierarchical zeolite templated carbons

Abstract

The achievement of hierarchical zeolite templated carbons (ZTCs) is firstly reported through the use of mesoporous zeolites as sacrificial scaffolds. The achieved hierarchical ZTCs feature both tailored microporosity and high degree of mesoporosity and allow hence to bridge the gap between classical ZTCs and CMK-like materials. Mesoporosity from steamed zeolites was meticulously transcribed to the ZTC particles. The use of zeolites featuring surfactant-templated mesoporosity allowed for achieving a ZTC with a very high mesopore volume (0.85 cm3 g−1). The rearrangement of surfactant-templated mesoporosity could be evidenced through nitrogen physisorption and transmission electron microscopy on ultramicrotomed samples. The rearrangement of mesoporosity during ZTC formation has been found to impact coherent crystal size and the lattice strain of the zeolite template. The combination of data from X-ray diffraction and nitrogen physisorption allowed further to reveal that the thickness of the ZTC skeleton is impacted by the degree of intracrystalline mesoporosity in the template zeolite. Through comparing the textural characteristics of the zeolite templates and of the achieved hierarchical ZTCs, important evidence was found that the surfactant-templating of USY zeolite leads to the development of a secondary amorphous phase and that the reduction of the microporous volume during this process is merely apparent.

Keywords

• Zeolite templated carbons
• ZTC
• Hierarchical
• Carbon
• Microporous
• Mesoporous