Theoretical and Practical Aspects of Zeolite Nucleation

First synthesis of SAPO molecular sieve with LTL-type structure by hydrothermal conversion of SAPO-37 with FAU-type structure

“…The crystal morphology and the surface Si/Al ratio were measured using scanning electron microscopy (SEM, Hitachi S-4800) and energy-dispersive X-ray chemical analysis (EDX). The 27 Al magic angle spinning (MAS) NMR, 29 Si MAS NMR, and 31 P MAS NMR spectra were recorded at 156.3, 119.2, and 242.8 MHz, respectively, on a Varian 600PS solid NMR spectrometer, using a 3.2-mm-diameter zirconia rotor for 27 Al and 31 P MAS NMR, and a 6-mm-diameter zirconia rotor for 29 Si MAS NMR. The rotor was spun at 15 kHz for 27 Al and 31 P MAS NMR, and at 6 kHz for 29 Si MAS NMR.…”

“…The 27 Al magic angle spinning (MAS) NMR, 29 Si MAS NMR, and 31 P MAS NMR spectra were recorded at 156.3, 119.2, and 242.8 MHz, respectively, on a Varian 600PS solid NMR spectrometer, using a 3.2-mm-diameter zirconia rotor for 27 Al and 31 P MAS NMR, and a 6-mm-diameter zirconia rotor for 29 Si MAS NMR. The rotor was spun at 15 kHz for 27 Al and 31 P MAS NMR, and at 6 kHz for 29 Si MAS NMR. The spectra were acquired using 2.2 ls pulses, a 1 s recycle delay, and 1000 scans for 27 Al MAS NMR, 2.8 ls pulses, a 10 s recycle delay, and 1000 scans for 31 P MAS NMR, and 6.2 ls pulses, a 100 s recycle delay, and 1000 scans for 29 Si MAS NMR.…”

“…The rotor was spun at 15 kHz for 27 Al and 31 P MAS NMR, and at 6 kHz for 29 Si MAS NMR. The spectra were acquired using 2.2 ls pulses, a 1 s recycle delay, and 1000 scans for 27 Al MAS NMR, 2.8 ls pulses, a 10 s recycle delay, and 1000 scans for 31 P MAS NMR, and 6.2 ls pulses, a 100 s recycle delay, and 1000 scans for 29 Si MAS NMR. Al(NO 3 ) 3 Á9H 2 O, 3-(trimethylsilyl)propionic-2,2,3,3-d 4 acid sodium salt, and H 3 PO 4 were used as chemical shift references for 27 Al, 29 Si, and 31 P MAS NMR, respectively.…”

Internal structure of a gel leading to NBA-ZSM-5 single crystals

“…The gel is an amorphous phase with a certain degree of stiffness and therefore sometimes referred to as solid when the liquid phase can easily be extracted from the stiff mass. The second category is characterized by the absence of a macroscopic gel and is referred to as "clear solution" and considered as a homogenous system [1,5]. In both systems, the study of the stages and species present during the formation of the crystals has aroused great interest.…”

A Statistical Rate Theory of Interface Concentration during Solution ZeoliteCrystal Growth

“…In such a process, the diffusion and reaction steps such as dissociation and integration of solute species at a terrace or at a step play an important role in determining the quality of the final products [11]. Several models have been proposed [12][13][14] based on the theory that the crystal surfaces grow in such a way that solute species in a supersaturated solution are first transported by diffusion and convection and then deposited onto the surface of the crystal by integration or an integration reaction with supersaturation being the driving force. Therefore, two points are worthy of note: first, the solution-mediated process is one in which the crystal growth is diffusion-controlled and, second, the surface reaction of soluble species with the crystal surface is rate-determining.…”