Alkali-Activated Zeolite 4A Granules-Characterization and Suitability Assessment for the Application of Adsorption

A major problem in the field of adsorbents is that binders (kaolin clay, bentonite) introduced to bind zeolites and ensure the needed mechanical strength, are not able to sorb gases like CO2 and N-2, and decrease the overall adsorption capacity. To solve this problem, one of the pathways is to introduce a binder able to sorb such gases. Thus, in this study, the physical and mechanical properties of a novel binder based on metakaolin and its composite with zeolite 4A in the granular form were studied. Metakaolin was used as a precursor for alkali-activated binder, which was synthesized using an 8M NaOH activation solution. Raw materials were characterized using granulometry, X-ray diffraction (XRD), and differential thermal analysis (DTA); and final products were characterized using density measurements, a compressive strength test, XRD, Brunauer-Emmett-Teller (BET) analysis, and scanning electron microscopy (SEM). Alkali-activated metakaolin was found to be efficient as a binding material when data for morphological properties were analyzed. A relationship was observed-by increasing the liquid-to-solid ratio (L/S), compressive strength decreased. Zeolite granule attrition was higher than expected: 2.42% and 4.55% for ZG-0.8, 3.64% and 5.76% for ZG-1.0, and 2.73% and 4.85% for ZG-1.2, measured at 4 and 5 atmospheres, respectively.

Automated summary

The study investigated the physical and mechanical properties of a novel binder based on metakaolin and its composite with zeolite 4A, demonstrating the effectiveness of alkali-activated metakaolin as a binding material for sorbent applications. An inverse relationship was observed between the liquid-to-solid ratio (L/S) and compressive strength, while higher-than-expected zeolite granule attrition was measured at increased pressure levels.