organic-structure-directing-agent-free-synthesis-for-bea-type-zeolite

Organic Structure-directing Agent-free Synthesis for *BEA-type Zeolite Membrane

Membrane separation has drawn attention as a novel-energy saving separation process. Zeolite membranes have great potential for hydrocarbon separation in ...

Waseda University

Zeolite membrane has been fabricated on porous alumina substrate in a single continuous process of gelation and subsequent crystallization while suppressing nucleation of zeolite powder in the bulk.

Hydrovapothermal conversion of tetraethoxysilane vapor to polycrystalline zeolite layer by in situ gelation.

We demonstrated that non-catalytic ethanol steam reforming proceeds efficiently and selectively without coking at the conditions of room temperature and atmospheric pressure using low-energy pulsed (LEP) discharge in combination with carbon fiber electrodes.

A novel method for hydrogen production from liquid ethanol/water at room temperature.

A preferentially oriented mordenite membrane was successfully prepared on a seeded porous a-alumina support. Characterization results of XRD (X-ray diffractometer) and FE-SEM (field emission scanning electron microscope) revealed that evolutionary selection might predominantly contribute to the formation of the sharply oriented mordenite membrane. The necessary conditions under which evolutionary selection occurs are: (a) the number density of nuclei on the support surface should be high enough at the early stage; (b) the crystals should grow fastest along one direction; and (c) the zeolite layer should proceed via the successive growth of the crystals nucleated on the support surface instead of the accumulation of the crystals formed in the bulk solution.

Growth mechanism of a preferentially oriented mordenite membrane.

Reverse-selective membranes, through which bigger molecules selectively permeate, are attractive for developing chemical processes utilizing hydrogen because they can maintain the high partial pressure of hydrogen required for their further downstream utilization. Although several of these chemical processes are operated above 473 K, membranes with outstanding reverse-selective separation performance at these temperatures are still to be reported. Herein, we propose a new adsorption-based reverse-selective membrane that utilizes a Na cation occluded in a zeolitic framework. The membrane developed in this work, a compact Na(+)-exchanged ZSM-5 (NaZSM-5) type zeolite membrane, enables us to selectively permeate and separate bigger polar molecules, such as methanol and water, from a stream containing hydrogen, above 473 K. On the other hand, a Na(+)-free, H(+)-exchanged ZSM-5 (HZSM-5) type zeolite membrane did not show separation properties at these temperatures. The microporous zeolite membrane developed in this study can be applied to a variety of chemical reaction systems to minimize energy consumption.

Reverse-selective microporous membrane for gas separation.

We investigated four catalytic reactions assisted with an electric field to promote catalytic activity, and we could achieve an effective process for hydrogen production at low temperatures, such as 423 K. In the presence of the electric field, four reactions of steam reforming of ethanol, decomposition of ethanol, water gas shift, and steam reforming of methane proceeded at very low temperature, such as 423 K, where a conventional catalytic reaction hardly proceeded. Conversion of reactant was greatly increased by the electric field, and apparent activation energies for these four reactions were lowered by the application of the electric field. This process can produce hydrogen and syngas by using a considerably small energy demand and has quick response.

Low-temperature hydrogen production by highly efficient catalytic system assisted by an electric field.

Highly stable FAU-type zeolite membrane for the separation of isopropanol (IPA)-water mixture by pervaporation is described. FAU membrane showed high water permselectivity and permeance. Comparison of FAU membrane with a conventional LTA-type zeolite membrane revealed superior stability of FAU zeolite membrane in a mixture containing a large water content. 

Zeolite Membrane for Dehydration of Isopropylalcohol-Water Mixture by Vapor Permeation.

Propylene/propane and ethylene/ethane separation was examined with Ag-exchanged X-type zeolite membrane (Ag-X membrane). The Na-X membrane was prepared on a porous tubular α-alumina support by a secondary growth method. The resulting Na-X membrane was ion-exchanged by using AgNO aq. Olefin selectivities in both mixtures were markedly improved after the ion exchange from Na to Ag cation. The Ag-X membrane exhibited a maximum propylene selectivity of 55.4 with a permeance of 4.13 × 10 mol m s Pa at 353 K for a propylene/propane (50:50) mixture. This membrane also exhibited a maximum ethylene selectivity of 15.9 with a permeance of 9.04 × 10 mol m s Pa at 303 K for an ethylene/ethane (50:50) mixture. We consider that the strong interaction between olefin and Ag cation plays an important role for the appearance of such high selectivity of olefin.

Article	Year
Hydrovapothermal conversion of tetraethoxysilane vapor to polycrystalline zeolite layer by in situ gelation. Chemical communications (Cambridge, England)\| PubMed ID: 15045120	2004
A novel method for hydrogen production from liquid ethanol/water at room temperature. Chemical communications (Cambridge, England)\| PubMed ID: 15614378	2005
Growth mechanism of a preferentially oriented mordenite membrane. Journal of Zhejiang University. Science. B\| PubMed ID: 15822149	2005
Reverse-selective microporous membrane for gas separation. Chemistry, an Asian journal\| PubMed ID: 19514028	2009
Low-temperature hydrogen production by highly efficient catalytic system assisted by an electric field. The journal of physical chemistry. A\| PubMed ID: 20235604	2010
Zeolite Membrane for Dehydration of Isopropylalcohol-Water Mixture by Vapor Permeation. ACS applied materials & interfaces\| PubMed ID: 26076213	2015
Olefin Selective Ag-Exchanged X-Type Zeolite Membrane for Propylene/Propane and Ethylene/Ethane Separation. ACS applied materials & interfaces\| PubMed ID: 30615839	2019

Masahiko Matsukata

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