Synthesis of FAU-Zeolite Membrane by a Secondary Growth Method: Influence of Seeding on Membrane Growth and Its Performance in the Dehydration of Isopropyl Alcohol-Water Mixture.

Y-type zeolite membranes were prepared on a porous tubular α-alumina support by a secondary growth process. Various experimental conditions such as seed size, pH of seed solution, and degassing of support were examined for understanding their influence on the membrane deposition process. The experimental results showed that the potential of alumina support surface and the USY seed slurry plays a significant role in controlling the electrostatic interaction between seed particles and support surface and also the aggregation of USY seed particles in the slurry. In addition, we also noted the significance of the capillary forces working at the three-phase interface on the support surface and is a key factor that governs the seeding behavior onto the tubular support surface. Optimization of these parameters resulted in crack-free compact membranes that were able to effectively separate a mixture of isopropyl alcohol and water in a vapor-phase separation process.

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

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.

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

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.

Reverse-selective microporous membrane for gas separation.

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.

Growth mechanism of a preferentially oriented mordenite membrane.

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.

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

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.

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

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.