Highly efficient crystallization of AlPO₄-5 accelerated by a rotating hydrothermal synthesis route

Abstract

Compared with static hydrothermal synthesis, the crystallization rate of an AlPO 4 -5 molecular sieve has been accelerated distinctly by a rotating hydrothermal synthesis route with obviously decreased crystal particle size, which is assumed to be ascribed to the increased nucleation centers, accelerated crystal nucleation and growth processes; five-coordinated Al is dominant in the initial reaction gel, and the assembly from amorphous Al species to long-range ordered crystals is mainly contributed by the conversion from five-coordinated Al to four-coordinated Al.

A nucleation-tuned mechanism to prepare centre-crossed zeolite lamellas by the rotating/static switch crystallization strategy

“…13 It is found that the relative crystallinity of the RS-series catalysts increases slightly with the increase of the rotation rate during the initial 0.5 day, which is ascribed to the accelerated crystal nucleation and consequently crystal growth of zeolite under a relatively high rotation rate. 20,21 The UV-vis spectra shown in Fig. S1 † indicate that four-coordination framework titanium is the fundamental Ti species in RS-series catalysts.…”

“…It is well-known that the hydrothermal method is an extensively used method to prepare zeolite and related materials, which can be conducted under static or rotating conditions, 20,21 and the electrostatic and van der Waals interactions play a crucial role in the formation of nuclei with preferred geometries. 22 Herein, a new switch crystallization strategy (SCS) is developed to synthesize MWW zeolite lamellas by the combination of crystallizations under rotating and static hydrothermal conditions.…”