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Title: Synthesis Strategies for Ultrastable Zeolite GIS Polymorphs as Sorbents for Selective Separations

Abstract

Designing zeolites with tunable physicochemical properties can substantially impact their performance in commercial applications such as adsorption, separations, catalysis, and drug delivery. Zeolite synthesis typically requires an organic structure-directing agent to obtain crystals with specific pore topology. Attempts to remove organics from syntheses to achieve commercially-viable methods of preparing zeolites often lead to the formation of impurities. Here, we present organic-free syntheses of two polymorphs of the small-pore zeolite P (GIS), P1 and P2. Using a combination of adsorption measurements and density functional theory calculations, we show that GIS polymorphs are selective adsorbents for H2O relative to other light gases (e.g., H2, N2, CO2).

Authors:
 [1];  [1];  [2];  [3];  [1];  [3];  [1]
  1. Department of Chemical and Biomolecular Engineering, University of Houston, Houston TX 77204 USA
  2. Department of Chemical and Biomolecular Engineering, University of Houston, Houston TX 77204 USA; Institute of Chemistry, University of the Philippines, Diliman Quezon City 1101 Philippines
  3. Applied Functional Materials, Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1340840
Report Number(s):
PNNL-SA-120609
Journal ID: ISSN 0947-6539; GT0200000
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemistry - A European Journal; Journal Volume: 22; Journal Issue: 45
Country of Publication:
United States
Language:
English

Citation Formats

Oleksiak, Matthew D., Ghorbanpour, Arian, Conato, Marlon T., McGrail, B. Peter, Grabow, Lars C., Motkuri, Radha Kishan, and Rimer, Jeffrey D.. Synthesis Strategies for Ultrastable Zeolite GIS Polymorphs as Sorbents for Selective Separations. United States: N. p., 2016. Web. doi:10.1002/chem.201602653.
Oleksiak, Matthew D., Ghorbanpour, Arian, Conato, Marlon T., McGrail, B. Peter, Grabow, Lars C., Motkuri, Radha Kishan, & Rimer, Jeffrey D.. Synthesis Strategies for Ultrastable Zeolite GIS Polymorphs as Sorbents for Selective Separations. United States. doi:10.1002/chem.201602653.
Oleksiak, Matthew D., Ghorbanpour, Arian, Conato, Marlon T., McGrail, B. Peter, Grabow, Lars C., Motkuri, Radha Kishan, and Rimer, Jeffrey D.. 2016. "Synthesis Strategies for Ultrastable Zeolite GIS Polymorphs as Sorbents for Selective Separations". United States. doi:10.1002/chem.201602653.
@article{osti_1340840,
title = {Synthesis Strategies for Ultrastable Zeolite GIS Polymorphs as Sorbents for Selective Separations},
author = {Oleksiak, Matthew D. and Ghorbanpour, Arian and Conato, Marlon T. and McGrail, B. Peter and Grabow, Lars C. and Motkuri, Radha Kishan and Rimer, Jeffrey D.},
abstractNote = {Designing zeolites with tunable physicochemical properties can substantially impact their performance in commercial applications such as adsorption, separations, catalysis, and drug delivery. Zeolite synthesis typically requires an organic structure-directing agent to obtain crystals with specific pore topology. Attempts to remove organics from syntheses to achieve commercially-viable methods of preparing zeolites often lead to the formation of impurities. Here, we present organic-free syntheses of two polymorphs of the small-pore zeolite P (GIS), P1 and P2. Using a combination of adsorption measurements and density functional theory calculations, we show that GIS polymorphs are selective adsorbents for H2O relative to other light gases (e.g., H2, N2, CO2).},
doi = {10.1002/chem.201602653},
journal = {Chemistry - A European Journal},
number = 45,
volume = 22,
place = {United States},
year = 2016,
month = 9
}
  • Designing nanoporous zeolites with tunable physicochemical properties can substantially impact their performance in commercial applications spanning diverse areas such as adsorption, separations, catalysis, and drug delivery. Zeolite synthesis typically requires the use of an organic structure-directing agent to facilitate the formation of crystals with specific pore size and topology. Attempts to remove organics from syntheses to achieve commercially-viable methods of preparing zeolites often lead to the formation of unwanted crystal polymorphs (i.e., impurities). Here, we present an organic-free synthesis of the small-pore zeolite P (GIS framework topology) that can be selectively tailored to produce two pure polymorphs: P1 and P2.more » To this end, we developed kinetic phase diagrams that identify synthesis compositions leading to the formation of GIS (P1 and P2), as well as their structural analogues MER and PHI. Using a combination of adsorption measurements and density functional theory (DFT) calculations, we also show that both GIS polymorphs are highly selective adsorbents for H2O relative to other light gases (e.g,, H2, N2, CO2). These studies highlight the potential application of GIS materials for dehydration processes, while our findings also refute prior theoretical studies postulating that GIS-type zeolites are excellent materials for CO2 separation/sequestration. Moreover, there is an impetus for discovering novel small-pore zeolites that are shape-selective catalysts for the production of value-added chemicals (e.g., light olefins); thus, our discovery of more thermally-stable P2 opens new avenues for exploring the potential role of this material as a high-performance catalyst.« less
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  • The impregnation of NaOH solution into the pores of cobalt-exchanged zeolite promoted the conventional reduction of cobalt ions with hydrogen gas. The method yielded catalysts that had high degrees of reduction and small cobalt clusters located inside zeolite pores. In the Fischer-Tropsch synthesis these catalysts showed a chain-extension effect, producing hydrocarbons higher than C{sub 10} in appreciable amounts, and an enhanced production of linear hydrocarbons such as 1-olefins and n-paraffins. The formation of long-chain hydrocarbons is attributed to an increased chance of the chain growth owing to a hold-up effect of reaction intermediates, especially 1-olefins, which are accumulated inside zeolitemore » pores during the reaction. Hydrocarbon isomers are produced over acidic sites of zeolite by secondary reactions (isomerization and cracking), which result in a chain shortening of the long-chain hydrocarbons.« less
  • The methods of diffuse-reflection optical spectroscopy and EPR were used to study the state of molybdenum in catalysts prepared by impregnating ultrastable zeolite with molybdenum salt solutions and by mixing in the solid phase with MoCl/sub 5/. It has been shown that molybdenum introduced into zeolites in small amounts is found basically in the form of isolated hexavalent ions of molybdenum. In addition, Mo/sup 5 +/ and Mo/sup 4 +/ ions are also present. Heteropolycompounds also form. The molybdenum ions are most readily reduced in the zeolite prepared by impregnation with a solution of ammonium paramolybdate.