Increasing the Productivity of Colloidal Zeolite Beta by Posthydrolysis Evaporation

Abstract

Colloidal beta zeolite is typically synthesized by the reaction of a clear precursor sol at temperatures below 100°C. The process usually suffers from limited batch productivity with a long reaction time, because of the large amount of water used in the precursor sol. Reducing the water content is expected to shorten the reaction time, enhance the productivity, and reduce the particle size, but proper procedures are required to achieve a supersaturated, but pourable, composition. A precursor sol having a record low H 2 O/SiO 2 ratio has been prepared by the addition of a posthydrolysis evaporation step. Compared to a conventional composition, which took 14 days to produce >100-nm particles at <16% yield, the supersaturated precursor achieved >60% yield of ∼55-nm redispersible zeolite beta particles in only 6 days. The formation of beta zeolite and the evolution of its particle size during the 90°C reaction confirmed that aggregation always occurred before colloidal zeolite particles could be extracted. On the other hand, the "amorphous" residue was also found to be microporous, suggesting that it might be smaller zeolite particles that were undetectable by XRD and did not settle even with the high-speed centrifugation employed.

Heteroaggregation and Selective Deposition for the Fine Design of Nanoarchitectured Bifunctional Catalysts: Application to Hydroisomerization

“…Preparation of the Colloidal Suspension of β-Zeolite Nanoparticles. As previously observed by Fang et al, 5 the high concentration of the synthesis gel favors nucleation over growth and hence produces, with a high yield, (ca. 50%) β-zeolite nanoparticles with good crystallinity and no impurity (ICDD file 00−047−0183) as shown by X-ray diffraction (Figure 1-a) and TEM (Figure 2-a).…”

Zeolite Beta Formation from Clear Sols: Silicate Speciation, Particle Formation and Crystallization Monitored by Complementary Analysis Methods

“…The aim of the present contribution is to study the early stages of the formation of zeolite beta from clear sols using TEAOH as the SDA in the presence or absence of NAs in the reaction mixture by controlling the initial Si/OH ratio. Although the mechanism of zeolite beta crystallization has been the subject of several studies in the past, the current contribution uses a combination of methods to register species in precursor solutions/sols. In addition, the evolution of these objects during crystallization under hydrothermal conditions is monitored.…”

Multidiagnostic analysis of silicate speciation in clear solutions/sols for zeolite synthesis

“…By progressive increase of the average silicon connectivity, NAs transform into larger nanoparticles (NPs). Zeolite crystallization proceeds, by aggregation of NPs into zeolite crystallites [5,[12][13][14][15][16].…”