In Situ Hydrothermal Conversion of Silica Gel Precursors to Binderless Zeolite X Pellets for Enhanced Olefin Adsorption

Binderless zeolite X pellets were “one-pot”-synthesized via in situ hydrothermal conversion of silica gel precursors in sodium aluminate solution. The conversion and crystallization kinetics were investigated as a function of synthesis time with a spectrum of techniques. It is found that four-membered rings (4R) and six-membered rings (6R) are formed by linking diffused Al species with dissolved Si species during the aging period, whereas the zeolite X frameworks are constructed via reorganization of β cages with double six-membered rings (D6R) in a crystallization process. Furthermore, the grand canonical Monte Carlo simulation was conducted to elucidate 1-hexene adsorption on zeolite X with ion species and exchange degree variation. Specifically, the adsorption capacity and guest–host interaction energy were evaluated. Incorporation of Mg2+ and Ca2+ enables a higher adsorption capacity, whereas introduction of Co2+, Ni2+, Cu2+, and Zn2+ boosts adsorption capacity and enhances interaction energy.