Interzeolite Transformation of Borosilicate MWW to Metallosilicate BEA-Type Zeolites: Separated Kinetics of Structural Transformation and Metal Substitution

The synthesis of cobalt-, nickel-, and zincosilicate beta zeolites(Co-BEA, Ni-BEA, and Zn-BEA, respectively) via a single-step hydrothermalinterzeolite transformation of borosilicate MWW (B-MWW) with eachmetal precursor solution was systematically investigated. While allthree metallosilicates exhibited distinct BEA structures with stableframework metal species, their structural transformation and metalsubstitution kinetics differed depending on the type of metal. Thecrystallization of Co-BEA and Ni-BEA was completed within two days,while that of Zn-BEA continued even after seven days. Apart from thecrystallization kinetics, the incorporation rate of Co into the frameworkof the BEA structure was slower than that of the other two metals.The characteristics of the BEA structure according to the type offramework heteroatom were further demonstrated using density functionaltheory calculations. Despite having a comparable metal content (ca.3 wt %), the Lewis acidities of fully crystallized Co-, Ni-, and Zn-BEAwere different corresponding to the types of framework metals. Thesethree metallosilicates showed good catalytic activity for Lewis acid-catalyzedglucose conversion, and the catalytic results were attributed to theintrinsic properties of the catalysts determined from their synthesisstage.

Automated summary

The synthesis and characteristics of cobalt, nickel, and zincosilicate beta zeolites (Co-BEA, Ni-BEA, and Zn-BEA) were investigated through a single-step hydrothermal interzeolite transformation of borosilicate MWW. The crystallization and metal substitution kinetics of the metallosilicates varied depending on the metal type. The Lewis acidities of the three metallosilicates were different despite having comparable metal content, and they showed good catalytic activity for glucose conversion.