Upscaling of W zeolite direct synthesis from coal fly ash and its water adsorption capacity

Abstract

BACKGROUND: Alkaline amorphization of fly ash (FA) and crystallization of the potassium W zeolite from the resultant amorphous materials was carried out at different scales by a straightforward hydrothermal method. The experimental factors and levels were evaluated during the FA amorphization study by variation of the metallic hydroxide, concentration, temperature and time for the hydrothermal reaction. RESULTS:The alkaline FA hydrothermal activation study quantified a set of optimal conditions to obtain amorphous materials easy to be recrystallized into W zeolite. The activation process at laboratory scale involved the hydrothermal treatment of 3.6 g FA with 74.43 mEq KOH dissolved in 21 mL water at 125 ∘ C for 4 h. A product with ≤94.7% of the amorphous phase was obtained. The direct zeolitization of FA was performed at 175 ∘ C for 16 h with a KOH:FA weight ratio of 0.33 and molar ratios of 1.64, 17.08 and 3.90 for SiO 2 :KOH, H 2 O:SiO 2 and SiO 2 :Al 2 O 3 , respectively. An amount of dried zeolitic material c.25% higher than the weight of FA used was obtained. CONCLUSION: Adsorbents formulated with the W zeolite showed higher water adsorption capacity than the commercial molecular sieves used by industry for drying wet natural gas.

In focus: materials and the environment symposium (XXVII IMRC México)

“…In this In Focus edition of the Materials and the Environment Symposium , 11 articles were selected for publication among all the amazing work that was presented during this event. This In Focus includes articles on the production of photocatalysts for the degradation of pollutants such as herbicides, as well as the use of sugar cane bagasse and coal fly ash for the production of adsorbent materials, and the production of materials with enhanced water adsorption for agricultural applications.…”