Fabrication of Highly Efficient ZIF-8@PEI Monoliths for CO₂ Capture Using Phosphorylated Cellulose Nanofiber as a Binder

Abstract

This study involves the synthesis and comparison of zeolitic imidazolate frameworks (ZIFs), specifically ZIF-8 and ZIF-67 pristine with a commercial zeolite, emphasizing their CO₂ affinity and sorption capability. To overcome challenges persisting in the handling and integration of these materials into industrial adsorption processes, particularly when limited to microcrystalline fine powders, we present herein an innovative manufacturing method to produce standalone monolithic supports. This process involves pseudoplastic paste formulations utilizing polyethylenimine (PEI) as a coagulant and locally fabricated phosphorylated cellulose nanofiber (PCNF) as a binding agent. Rheological investigation was conducted to anticipate the required shaping and design by means of paste flowability, consistency, and stiffness. XRD and FTIR results confirm the preservation of crystalline structure and the occurrence of amine functionalization associated with the presence of PEI, respectively. The proposed method significantly enhances the CO₂ adsorption performance of the produced ZIF-8 monolith in comparison with that reached when using the pristine material, achieving a capacity of 1.25-2 mmol·g^-1 at 30 °C under dry conditions in a pressure range of 1-13 bar, respectively. In other words, this work clearly highlights an effective applicability of the ZIF-8 monolith as an innovative sorbent for further designing CO₂ capture industrial setups.