FAU-Type Zeolite Nanocasted Carbon Replicas for CO₂ Adsorption and Hydrogen Purification

Microporous ordered carbon have been synthesized by the nanocasting process from zeolite Y using acetylene and furfuryl alcohol as carbon precursors. If the proper synthesis conditions are chosen, these materials retain the long-range order of the zeolite mold. The resulting carbons possess a large surface area (≥2200 m 2 /g), a high microporosity (≥1.0 cm 3 /g), and a controlled pore size distribution, which was tailored by the wall thickness of the zeolite template. Because of their high micropore volume, the carbon replicas of zeolite Y are attractive adsorbent materials and might be used to replace conventional activated carbons as adsorbents in pressure swing adsorption processes (PSAs) for H 2 purification. In the present contribution, we evaluate the adsorption capacity of the carbon replicas in a H 2 -PSA based on their single-component adsorption isotherms of CO 2, CH 4, and N 2 measured at room temperature. The ideal adsorbed solution theory (IAST) was used to predict the co-adsorption of CO 2 /CH 4 /N 2 gas mixtures and to evaluate the working capacity of the materials under typical operating conditions of a H 2 -PSA process. The comparison of the working capacities shows that the carbon replicas largely outperform conventional activated carbons while having comparable CO 2 /CH 4 and CO 2 /N 2 selectivity.