Nucleation and crystallization of the MWW-type lamellar zeolitic precursor

Author(s)

Schwanke, Anderson Joel ; Vinaches, Paloma ; Meneau, Florian ; Morgado, Edisson, Jr. ; Pergher, Sibele

• Document type: Journal article
• Source: CATALYSIS TODAY; v. 344, p. 6-pg., 2020-03-15.

Abstract

The nucleation and crystallization of the layered zeolitic precursor (P)MCM-22 with Si/Al gel ratio = 25 was studied by several characterization techniques such as X-ray Diffraction (XRD), Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Infrared Spectroscopy (IR), Thermogravimetric Analysis (TGA) and Small-Angle X-ray Scattering (SAXS). The crystallization kinetics of the samples was firstly monitored by XRD identifying reflections from the sample obtained at 48 h. The ICP-OES analysis concluded that the Si/Al ratio was 23, which is very similar to the initial gel one. SEM analyses corroborated the XRD results observing the formation of smooth particles from 48 h of crystallization and, after 168 h, the formation of thin platelet-like particles. The IR results showed an increase of external silanol groups when the crystallization time increases, due to terminating silanol groups between zeolitic crystals, whereas the bands attributed to the structure directing agent-hexamethyleneimine (HMI) - increase up to 168 h. Finally, the SAXS results indicated the existence of primary nanoparticles population in the first stages of the reaction, allowing to follow their growth and transformation from spherical morphology to two-dimensional objects forming aggregates. (AU)

• FAPESP's process: 17/23427-0 - Study of zeolites nucleation by Small-Angle X-ray Scattering and Coherent X-ray imaging techniques.
• Grantee: Paloma Vinaches Melguizo
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 14/25964-5 - From the monomers to the nanoparticles: in situ real time investigation of gold nanoparticles formation by synchrotron and microscopy techniques
• Grantee: Florian Edouard Pierre Meneau
• Support Opportunities: Research Grants - Young Investigators Grants