Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
  • B01D71/02—Inorganic material
  • B01D71/028—Molecular sieves
  • B01D71/0281—Zeolites
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
  • B01D53/228—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion characterised by specific membranes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
  • B01D67/0039—Inorganic membrane manufacture
  • B01D67/0051—Inorganic membrane manufacture by controlled crystallisation, e,.g. hydrothermal growth
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
  • B01D67/0081—After-treatment of organic or inorganic membranes
  • B01D67/0083—Thermal after-treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/10—Supported membranes; Membrane supports
  • B01D69/108—Inorganic support material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/50—Carbon oxides
  • B01D2257/504—Carbon dioxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2323/00—Details relating to membrane preparation
  • B01D2323/24—Use of template or surface directing agents [SDA]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/02—Details relating to pores or porosity of the membranes
  • B01D2325/0283—Pore size
  • B01D2325/02831—Pore size less than 1 nm
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/04—Characteristic thickness
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/22—Thermal or heat-resistance properties
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
  • Y02C20/00—Capture or disposal of greenhouse gases
  • Y02C20/40—Capture or disposal of greenhouse gases of CO2

Definitions

• the invention relates to a membrane for gas phase separation and to a process for producing such a membrane.
• the fossil fuel before the actual combustion of the carbon is removed by the fuel is converted by a partial oxidation or reforming in CO 2 and hydrogen gas (separation task: CO 2 / H 2 ), combustion of hydrogen.
• the CO 2 can be washed out by physical or chemical washing solutions.
• the separation of the CO 2 from the gas mixture is easier than described under point a), as there are also significantly higher concentrations and pressures for the CO 2 .
• a potentially suitable method with significantly lower efficiency losses is gas separation via ceramic microporous membranes.
• Ceramic membranes have high chemical and thermal stability and can be used in all three power plant routes.
• existing microporous membranes do not yet reach the required pore size diameter for gas separation, have insufficient permeation or separation rates or are not stable under process conditions.
• the permeation rate represents the volume flow per unit time of the permeating component relative to the membrane surface and the applied partial pressure difference across the membrane [m 3 / m 2 hbar].
• the selectivity is described by the so-called separation factor, which is given by the ratio of the permeation rate of the gases to be separated. In order to achieve better values here, a targeted adjustment of the microstructure in the nanometer range is desirable.
• Zeolite membranes are crystalline microporous, inorganic membranes.
• the driving forces for a separation are the affinity of the permeating molecules for the zeolite material on the one hand and the difference between the molecular sizes and the pore diameters of the membrane on the other hand.
• the best studied membranes belong to the MFI type, although mordenite or zeolites A and Y have also been studied.
• the zeolites of the faujasite type (Y, X and K) are also described in the literature as being suitable in principle for gas phase separation.
• microporous separation membranes In the case of the microporous separation membranes, a distinction is made between crystalline zeolitic membranes from the SiO 2 -AbO 3 system and amorphous from the systems SiO 2 -Al 2 O 3 , TiO 2 , ZrO 2 . In the crystalline membranes, especially defects in the layers (intergranular pores, defects) or too large pore diameters are the reason for an insufficient separation rate.
• zeolites are synthesized hydrothermally.
• SDA structure directing agent
• zeolites crystallize at about 100-200 0 C under autogenous pressure from aqueous solutions.
• Particularly suitable as SDA are quaternary ammonium salts, which are decomposed and liberated in the course of calcination and thus make the pore space accessible.
• the mechanism of crystallization has been the subject of controversy for many years, in particular on the role of precursors, which should form in homogeneous solution in the interaction of silica with SDA.
• the targeted introduction of seed crystals onto a substrate can influence the growth of germs.
• the mechanical rubbing of the seed crystals with the aid of cationic polymers into the surface is known.
• crystals are applied as alcoholic dispersion or via sols, including silicon compounds, water, a base, structuring agent and an aluminum salt, directly onto the substrate.
• the particle size of the sols is usually in the range between 50 nm and 200 nm.
• the use of such sols is referred to as secondary grain growth.
• the substrate is then with a zeolite layer coated (eg by dip coating) and then treated hydrothermally. This results in a layer thickness of about 200 nm. This secondary growth process of zeolite granules allows targeted control of the microstructure by decoupling of nucleation and seed growth.
• the object of the invention is to provide a separation device for a gas phase separation with porosities in the range of 0.2-0.45 nm, by means of which it is possible, in particular N 2 / O 2 -, N 2 / CO 2 - H 2 / CO 2 - or CO 2 / CH 4 - to separate gas mixtures. Insbesondre this separator should be integrated directly into thermal processes and therefore be particularly temperature stable. Furthermore, it is the object to provide a method for producing such a device.
• a separating device suitable for gas phase separation can be obtained by a defect-free ceramic membrane made of zeolite structures, in which a nanostructured microstructure with porosities in the range of 0.2 through targeted modification of the starting reagents and the production parameters and subsequent aftertreatment - 0.45 nm can be adjusted.
• the invention relates to a process for the preparation of crystalline microporous nanoscale ceramic layer systems and to a producible therewith Separating device in particular for use as a gas separation membrane in fossil power plants.
• the membrane according to the invention comprises a nanocrystalline zeolite layer having an average pore diameter of 0.2 to 0.45 nm, which is arranged on a porous substrate.
• Suitable zeolite structures are, in addition to zeolite frameworks with 4-ring pores, also those with 6 and / or 6 Ring pores, which usually have the required small pore sizes in the range of 0.2 to 0.45 nm.
• the suitable zeolites for this application are usually pure silicon zeolites. In the context of the invention, however, those are also included which additionally contain small amounts of Al 2 O 3 , TiO 2 , Ti 2 O 5 , Fe 2 O 3 , GeO 2 , B 2 O 3 , Ga 2 O 3 or other metals can have. However, the amounts are so small that they have no influence on the mode of action of the zeolite layer.
• Suitable zeolite framework structures are, for example, DDR, DOH, LTA, SGT, MTN and SOD and mixtures of these structures.
• the zeolite layer thus has significantly smaller pore sizes than known MFI zeolites having a pore size greater than 0.55 nm.
• the structure in particular the accuracy of the crystalline zeolite layer, is crucial for use as a gas separation membrane. Only with a layer with few defects can an optimum between permeation and selectivity be achieved even with a small layer thickness.
• the membrane according to the invention has at least one crystalline zeolite layer with a layer thickness of 50 nm up to 2 ⁇ m.
• the nano-crystalline zeolite layer of the membrane according to the invention is arranged on a porous substrate which regularly has a mean pore diameter of 2 nm to 2 ⁇ m and comprises, for example, steel, aluminum, titanium, silicon, zirconium, aluminosilicates or else cerium and mixtures thereof ,
• a colloidal starting solution and its metastable complexes which comprise zeolites in the form of nanocrystals as membrane precursors (precursors).
• These zeolite precursors are applied to a mesoporous substrate by a wet separation method such as spin coating, dip coating, wet powder spraying and screen printing.
• the layer is transferred to a crystalline microporous zeolite layer with pore sizes between 0.2 to 0.5 nm.
• Suitable silicon compounds are organic silicon compounds, such as, for example, tetraethyl orthosilicate (TEOS) or else tetra-methyl orthosilicates (TMOS) or else inorganic silicon compounds, such as silicon dioxide, a silicon gel or colloidal silicon.
• TEOS tetraethyl orthosilicate
• TMOS tetra-methyl orthosilicates
• inorganic silicon compounds such as silicon dioxide, a silicon gel or colloidal silicon.
• SDA structure-directing-agent
• SDA structure-directing-agent
• the colloidal solution may also contain alcohols.
• the colloidal solution advantageously has zeolite crystallites with a size between 2 and 25 nm, in particular between 2 and 15 nm.
• the colloidal solution is applied to the porous substrate using typical wet application techniques such as spin coating, dip coating, screen printing or spraying techniques.
• a dense application produces crystalline particles with a size between 2 and 20 nm.
• the actual synthesis of the crystalline zeolite layer is hydrothermally at temperatures between 50 and 250 0 C and autogenous pressure.
• the pH is adjusted above 9.
• the pH may be lower than 9 (eg, 7) when fluoride anions are present in the hydrothermal solution.
• the composition of the hydrothermal solution must have at least water, but optionally it may also contain a base, F " ions, SDA or silicon compounds, and after a few hours the formation of the crystalline zeolite layer takes place.
• the method according to the invention has the following advantages in particular:
• nano-crystalline colloids enables the production of a virtually defect-free membrane, which has only a very small number of cracks or holes in the microporous layer.
• the zeolite coating can be used directly as a separation membrane or can be produced by recrystallization and regrowth during a hydro-thermal treatment.
• the kinetic diameters of the gases to be separated generally define the pore size of the zeolite framework types which are particularly suited to the separation problem.
• 10-ring pores with a width of approx. 0.55 nm provide even better diffusion properties for mass transfer but at the expense of the molecular sieve effect.
• Suitable zeolite frameworks, which have pore openings of about 0.2 to 0.5 nm and therefore should in principle have the required selectivity, are therefore to be found in particular in the case of the 4-, 6- or even 8-ring zeolite structures.
• pore crosslinking In addition to the pore diameter, however, pore crosslinking also plays an important role. In zeolite scaffold types with a three-dimensionally crosslinked pore o system, the orientation of the crystallites on the substrate interface plays only a minor role. In contrast, lower-dimensional pore systems require an oriented deposition of the zeolite frameworks in order to achieve an optimum separation effect and optimum transport performance through the membrane.
• the zeolite types DDR, DOH, LTA, SGT, MTN, SOD, CHA and mixtures thereof have proven to be particularly suitable from the large number of zeolite framework structures.
• zeolite framework types are flexible in their composition.
• hydrophobic, pure SiO 2 scaffolds can be synthesized that become increasingly hydrophilic by replacement of Si at the tetrahedral position with trivalent cations such as Al, B, Fe, and others, and contain non-framework cations for charge compensation These are then ion exchange reactions available or represent in the protonated form, the reactive centers in acid-catalyzed reactions. Also, the adsorption is influenced by the charge of the unit cell. Molecular sieving is predominant for zeolites with pore sizes in the range of 0.3-0.5 nm. 5
• the invention relates to a process for the hydrothermal production of a microporous membrane, in which a colloidal solution comprising zeolite frameworks with A, 6 and / or 8 ring pores, which are present as crystallites in a size between 2 and 25 nm, using a Nassaufbringungstechnik on a porous substrate is applied.
• the applied layer is hydrothermal
• a nano-crystalline microporous zeolite layer is synthesized having a mean pore diameter of 0.2 to 0.45 nm.
• Such a microporous membrane comprising a porous substrate and at least one nanocrystalline zeolite layer having an average pore diameter of 0.2 to 0.45 nm arranged thereon is advantageously suitable for use as a separation device for a gas phase separation with the aid of which it is possible, in particular N 2 / O 2 -, N 2 / CO 2 - to separate H 2 / CO 2 - or CO 2 / CH 4 - gas mixtures.
• This separating device is particularly temperature-stable and can therefore be integrated directly in thermal processes.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Thermal Sciences (AREA)
• Physics & Mathematics (AREA)
• Geology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Analytical Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Silicates, Zeolites, And Molecular Sieves (AREA)

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• 2005
  • 2005-04-08 DE DE102005016397A patent/DE102005016397A1/de not_active Withdrawn
• 2006
  • 2006-04-01 US US11/887,816 patent/US20090266237A1/en not_active Abandoned
  • 2006-04-01 JP JP2008504614A patent/JP2008534272A/ja not_active Withdrawn
  • 2006-04-01 EP EP06722743A patent/EP1877167A1/de not_active Withdrawn
  • 2006-04-01 WO PCT/DE2006/000593 patent/WO2006105771A1/de not_active Ceased

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