Zeolite ceramics with ordered microporous structure and high crystallinity prepared by cold sintering process

Abstract

4A [Na 96 (Al 96 Si 96 O 384 )⋅216H 2 O] and 13X [Na 2 (Al 2 Si 3.3 O 10.6 )⋅7H 2 O] zeolite ceramics were prepared by cold sintering processes, and the physical properties were investigated together with the structure characterization. There were four primary parameters controlling the preparation process: content of NaOH, pressure, temperature, and holding time. Zeolite ceramics with the idea ordered microporous structure and high crystallinity were obtained at 393 K under 450~550 MPa with a holding time of 5 min from the solution with 20 wt% NaOH. A high compressive strength up to 60 MPa and low Young's modulus down to 76 MPa were achieved in 13X zeolite ceramics, and the present ceramics might provide potential applications in damping materials and thermal insulating materials.

Realizing translucency in aluminosilicate glass at ultralow temperature via cold sintering process

“…This result is very different from Ref. [30] for cold-sintered 4A and 13X zeolites, which showed the completely same zeolite structure after the CSP. On the one hand, the CSPinduced phase transformation reflects the weak stability of the EMT compared to other zeolites.…”

“…Since the zeolites [37,38] are frequently synthesized by hydrothermal methods, during which the NaOH solution was introduced to react with the aluminum and silicon compounds through the joint action of temperature and pressure in a closed reactor, and the environment for preparing the NS-glass via the CSP with pressure and solution is similar to the hydrothermal conditions. Thus, it is reasonable to deduce that the densification of amorphous aluminosilicate can be accelerated by the analogous process for synthesizing zeolite powder [30,37,39]. Surprisingly, there is no obvious Na-rich position on the fracture surface of the NS-glass (Figs.…”

“…Due to the high Al/Si ratio and surface area, the EMT powder shows weak thermal stability upon heating. Although the CSP of several zeolite powders, such as 4A, 13X, and Y types, has been demonstrated before [30], dense glass materials with certain transmittance have never been achieved, highlighting the importance of this study.…”

Characterization of Ceramic Membrane based on Calcium Carbonate from Onyx Stone and Its Application for Coconut Sap Treatment

“…Figure 1a presents the XRD patterns of the unsintered membrane sample and those sintered at 1200 o C. It reveals that the crystalline phases detected for the un-sintered sample (M1) consists of kaolin at 2θ = 20.9 o and 24.9 o [16][17][18], quartz, zeolite at 2θ = 27.2 o [19], and calcite (CaCO3) at 2θ = 30 o . In the sample sintered at 1200 o C (CM1), a zeolite crystal is formed followed by cristobalite, mullite (3Al2O32SiO2), and then by the crystallization of gehlenite (Ca2Al2SiO7).…”

Effects of Cold Sintering on the Performance of Zeolite 13X as a Consolidated Adsorbent for Cesium

“…Recently, Shi et al implemented a cold sintering technique for zeolites A and X by controlling the NaOH content, pressure, temperature, and holding time. 33 They focused only on the mechanical properties of the cold sintered samples, without considering the inherent zeolite structures, chemical durabilities, and adsorption capacities. Thus, the effects of pressure, temperature, and liquid agents on the nanoporous structures and performance of consolidated zeolites are yet to be systematically explored.…”