摘要:
A process for modifying surfaces of zeolites and molecular sieve membranes to decrease effective pore size for separation of materials includes atomic layer controlled vapor or liquid deposition. The atomic layer controlled deposition process steps include (i) exposing the surface to a metal atom coordinated with ligand groups having bonds that are hydrolyzable to form molecular bonded structures on the surface, which structures comprise the metal atoms coordinated with the ligand group or a modified ligand group and then (ii) hydrolyzing the bonds and possibly, but not necessarily, cross-linking the bonds in the ligand or modified ligand group.
摘要:
A modified zeolite or molecular sieve membrane for separation of materials on a molecular scale. The modified membrane is fabricated to wholly or partially block regions between zeolite crystals to inhibit transfer of larger molecules through the membrane, but without blocking or substantially inhibiting transfer of small molecules through pores in the crystalline structure. The modified membrane has a monomolecular layer deposited on the zeolite surface which has coordinated groups of atoms that include (i) a metal atom bonded to oxygen atoms that are bonded to the zeolite substrate atoms (e.g., silicon atoms) and (ii) either hydroxyl groups bonded to the metal atoms or additional oxygen atoms bonded to the metal atoms.
摘要:
The invention provides chemically activated valves based on crystalline molecular sieve membranes. Adsorption of a swelling agent within the pores of the molecular sieve crystals limits transport through the membrane. Desorption of the swelling agent can re-establish transport through the membrane. This valving mechanism can be used in methods for storing and dispensing various substances.
摘要:
SAPO-34 membranes and methods for their preparation and use are described. The SAPO-34 membranes are prepared by contacting at least one surface of a porous membrane support with a synthesis gel comprising a first and a second templating agent. SAPO-34 crystals having a narrow size distribution were applied to the surface of the support prior to synthesis. A layer of SAPO-34 crystals is formed on at least one surface of the support. SAPO-34 membranes of the invention can have improved selectivity for certain gas mixtures, including mixtures of carbon dioxide and methane.
摘要:
Zeolite membranes that can be used to continuously separate components of mixtures are disclosed. The zeolite membranes are prepared by isomorphous substitution, which allows systematic modification of the zeolite surface and pore structure. Through proper selection of the basic zeolite framework structure and compensating cations, isomorphous substitution permits high separation selectivity without many of the problems associated with zeolite post-synthesis treatments. The inventive method for preparing zeolite membranes is alkali-free and is much simpler than prior methods for making acid hydrogen zeolite membranes, which can be used as catalysts in membrane reactors.
摘要:
The present invention provides methods for making improved zeolite and crystalline silicoaluminophosphate (SAPO) membranes, in particular SAPO-34 membranes, on a porous support through improved removal of the organic structure-directing templating agent. A calcining step is performed in an oxygen free atmosphere, such as under a vacuum or inert gas, to remove the organic templating agent. By removing the templating agent in the absence of oxygen, the calcination step can remove a greater amount of the templating agent than comparable template removal steps conducted in the presence of oxygen and the calcination step can be conducted at significantly lower temperatures. The membranes of the present invention provide increased permeance while maintaining comparable selectivity for gas separations, particularly carbon dioxide (CO2) and methane (CH4) separations and separations at high temperatures.
摘要:
A dye-sensitized solar cell (DSSC) is provided. The DSSC anode includes a first electron-collecting layer deposited on a substrate and a first electron-transporting layer deposited on the first electron-collecting layer, the first electron-transporting layer containing light-absorbing dye. The DSSC anode also includes a second nanoporous electron-collecting layer deposited on the first electron-transporting layer; and a second electron-transporting layer deposited on the second porous electron-collecting layer, the second electron-transporting layer containing light-absorbing dye. Methods of fabricating the DSSC anode are also provided.
摘要:
The present invention provides modified molecular sieve membranes with improved CO2/CH4 separation selectivity and methods for making such membranes. The molecular sieve membranes are modified by adsorption of a modifying agent, such as ammonia, within and/or on the membrane.
摘要:
The present invention provides methods for making improved zeolite and crystalline silicoaluminophosphate (SAPO) membranes, in particular SAPO-34 membranes, on a porous support through improved removal of the organic structure-directing templating agent. A calcining step is performed in an oxygen free atmosphere, such as under a vacuum or inert gas, to remove the organic templating agent. By removing the templating agent in the absence of oxygen, the calcination step can remove a greater amount of the templating agent than comparable template removal steps conducted in the presence of oxygen and the calcination step can be conducted at significantly lower temperatures. The membranes of the present invention provide increased permeance while maintaining comparable selectivity for gas separations, particularly carbon dioxide (CO2) and methane (CH4) separations and separations at high temperatures.
摘要:
The present invention provides modified molecular sieve membranes with improved CO2/CH4 separation selectivity and methods for making such membranes. The molecular sieve membranes are modified by adsorption of a modifying agent, such as ammonia, within and/or on the membrane.