ChemInform Abstract: Grain Boundary Defect Elimination in a Zeolite Membrane by Rapid Thermal Processing.

ChemInform ◽  
2009 ◽  
Vol 40 (41) ◽  
Author(s):  
Jungkyu Choi ◽  
Hae-Kwon Jeong ◽  
Mark A. Snyder ◽  
Jared A. Stoeger ◽  
Richard I. Masel ◽  
...  
Science ◽  
2009 ◽  
Vol 325 (5940) ◽  
pp. 590-593 ◽  
Author(s):  
Jungkyu Choi ◽  
Hae-Kwon Jeong ◽  
Mark A. Snyder ◽  
Jared A. Stoeger ◽  
Richard I. Masel ◽  
...  

Microporous molecular sieve catalysts and adsorbents discriminate molecules on the basis of size and shape. Interest in molecular sieve films stems from their potential for energy-efficient membrane separations. However, grain boundary defects, formed in response to stresses induced by heat treatment, compromise their selectivity by creating nonselective transport pathways for permeating molecules. We show that rapid thermal processing can improve the separation performance of thick columnar films of a certain zeolite (silicalite-1) by eliminating grain boundary defects, possibly by strengthening grain bonding at the grain boundaries. This methodology enables the preparation of silicalite-1 membranes with high separation performance for aromatic and linear versus branched hydrocarbon isomers and holds promise for realizing high-throughput and scalable production of these zeolite membranes with improved energy efficiency.


Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 623
Author(s):  
Eiji Hayakawa ◽  
Shuji Himeno

The synthesis of DDR-type zeolite membranes faces the problem of cracks that occur on the zeolite membrane due to differences in the thermal expansion coefficient between zeolite and the porous substrate during the detemplating process. In this study, Al-containing ZSM-58 zeolite membranes with DDR topology were prepared by rapid thermal processing (RTP), with the aim of developing a reproducible method for preparing DDR zeolite membrane without cracks. Moreover, we verified the influence of RTP before performing conventional thermal calcination (CTC) on ZSM-58 membranes with various silica-to-aluminum (Si/Al) molar ratios. Using the developed method, an Al-containing ZSM-58 membrane without cracks was obtained, along with complete template removal by RTP, and it had higher CO2/CH4 selectivity. An all-silica ZSM-58 membrane without cracks was obtained by only using the ozone detemplating method. ZSM-58 crystals and membranes with various Si/Al molar ratios were analyzed by using Fourier-transform infrared (FTIR) spectroscopy to confirm the effects of RTP treatment. Al-containing ZSM-58 zeolites had higher silanol concentrations than all-silica zeolites, confirming many silanol condensations by RTP. The condensation of silanol forms results in the formation of siloxane bonds and stronger resistance to thermal stress; therefore, RTP caused crack suppression in Al-containing ZSM-58 membranes. The results demonstrate that Al-containing ZSM-58 zeolite membranes with high CO2 permeance and CO2/CH4 selectivity and minimal cracking can be produced by using RTP.


2019 ◽  
Vol 8 (1) ◽  
pp. P35-P40 ◽  
Author(s):  
Haruo Sudo ◽  
Kozo Nakamura ◽  
Susumu Maeda ◽  
Hideyuki Okamura ◽  
Koji Izunome ◽  
...  

1994 ◽  
Vol 141 (11) ◽  
pp. 3200-3209 ◽  
Author(s):  
Charles D. Schaper ◽  
Mehrdad M. Moslehi ◽  
Krishna C. Saraswat ◽  
Thomas Kailath

1990 ◽  
Vol 29 (Part 2, No. 1) ◽  
pp. L137-L140 ◽  
Author(s):  
Hisashi Fukuda ◽  
Akira Uchiyama ◽  
Takahisa Hayashi ◽  
Toshiyuki Iwabuchi ◽  
Seigo Ohno

1987 ◽  
Vol 92 ◽  
Author(s):  
A. Usami ◽  
Y. Tokuda ◽  
H. Shiraki ◽  
H. Ueda ◽  
T. Wada ◽  
...  

ABSTRACTRapid thermal processing using halogen lamps was applied to the diffusion of Zn into GaAs0.6 P0.4:Te from Zn-doped oxide films. The Zn diffusion coefficient of the rapid thermal diffused (RTD) samples at 800°C for 6 s was about two orders of magnitude higher than that of the conventional furnace diffused samples at 800°C for 60 min. The enhanced diffusion of Zn by RTD may be ascribed to the stress field due to the difference in the thermal expansion coefficient between the doped oxide films and GaAs0.6P0.4 materials, and due to the temperature gradient in GaAs0.6P0 4 materials. The Zn diffusion coefficient at Zn concentration of 1.0 × l018 cm−3 was 3.6 × 10−11, 3.1 × 10−11 and 5.0 × 10−12 cm2 /s for the RTD samples at 950°C for 6 s from Zn-, (Zn,Ga)- and (Zn,P)-doped oxide films, respectively. This suggests that Zn diffusibility was controlled by the P in the doped oxide films.


2000 ◽  
Vol 361-362 ◽  
pp. 454-457 ◽  
Author(s):  
O. Schenker ◽  
M. Klenk ◽  
E. Bucher

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