• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Filtration membrane of high chemical resistance comprising a porous support with a titanium oxide main powder and a secondary powder of titanium oxide, where the main powder has a particle size between 10-50 microns, and the secondary powder has a granulometry at least 2 times smaller than the granulometry of the main powder, the granulometry of the secondary powder being greater than 5 microns, and wherein the main powder represents at least 50% by weight with respect to the total weight of the porous support, such that the porous support it has a pore size between 1 and 7 microns and a percentage of porosity greater than 30%. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2684634A1
    申请号:ES201700329
    申请日:2017-03-30
    公开日:2018-10-03
    发明作者:Jaione OLLO LOINAZ；Benjamin GOIKOETXEA GALDEANO；Francisco Javier LOPETEGUI GARNICA
    申请人:Likuid Nanotek S L；LIKUID NANOTEK SL；
    IPC主号:
    专利说明:

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    DESCRIPTION
    High chemical resistance filtration membrane.
    Technical sector
    The present invention relates to the filtration elements used for the separation of different components contained in a liquid. The invention proposes a filtration membrane with a porous support made of a single ceramic material, titanium oxide, of a high purity and a narrow pore size distribution, which results in adequate filtration characteristics, mechanical strength and high resistance to chemicals during operation and the different cleaning processes.
    State of the art
    The filtration membranes comprise a porous ceramic support on which thin ceramic layers are deposited. The porous support provides the mechanical rigidity necessary for the functioning of the membrane and is responsible for supporting the ceramic layers, while the ceramic layers function as a semipermeable physical barrier that separates the substances contained in the liquid to be filtered based on their size .
    For the manufacture of the porous supports, a ceramic paste with ceramic particles of aluminum oxide (AI2O3), titanium oxide (TiO2), silicon oxide (SiO2), silicon carbide (SiC) or a combination thereof, is prepared. which is extruded using different nozzles to obtain porous supports "in green". After extrusion, the porous supports "in green" are subjected to a drying process and subsequently subjected to a sintered heat treatment in a high temperature oven until obtain the degree of densification necessary to achieve the characteristics of porosity, resistance and permeability required.
    On the one hand, the support must have a suitable average pore size, a narrow pore size distribution and a high porosity to be able to support the layers to be deposited on it. On the other hand, the support must have a high mechanical and chemical resistance to avoid fractures and withstand extreme pHs and chemical washes under aggressive alkaline and acidic conditions, which can be increased with the temperature of the solution.
    One of the ceramic materials most used in the manufacture of porous supports is aluminum oxide (AI2O3), with which supports of high mechanical resistance are obtained. However, the melting temperature of the aluminum oxide particles is very high, requiring high sintering temperatures (> 1700 ° C) to obtain a suitable porosity for the application of the microfiltration layers.
    Porous supports that use a mixture of ceramic materials, such as mixed aluminum oxide particles, among other ceramic materials, with titanium oxide are also known. These supports allow lower sintering temperatures to be used, since the titanium oxide particles have a lower melting point than the aluminum oxide particles, of the order of 200 ° C less, however the union of different ceramic materials creates weak points that lead to a decrease in the mechanical resistance of the support, where these points are more sensitive to chemical attacks.
    Porous supports made solely with titanium oxide are also known. These supports have the advantage of requiring a lower melting temperature than the supports that use aluminum oxide and also prevent weak points from being generated since a single ceramic material is used. Generally these supports are manufactured with
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    main particles of coarse granulometry that are mixed with fine particles of the size of the order of 1 miera which is a size considerably smaller than that of the main particles. The fine particles have a greater reactivity than the coarse particles so that during sintering they act as inorganic binder of the coarse particles. Despite the above-mentioned advantages, using particles with such granulometries makes it difficult to control the porosity of the support obtained, and therefore does not allow obtaining a porous support with a narrow pore size distribution, which is an essential requirement of the membranes of filtration since it is required to have the highest possible porosity while maintaining adequate mechanical strength of the support.
    A filtration membrane with a titanium oxide support suitable for the application of filtration layers is therefore necessary, with an average pore size especially suitable for microfiltration, ultrafiltration and nanofiltration applications, a narrow pore size distribution and a high porosity, as well as a mechanical resistance and a resistance against chemicals as high as possible.
    Object of the invention
    The invention relates to a filtration membrane with a porous support manufactured with a preferred granulometric selection that allows to obtain an adequate porosity, a high mechanical resistance and a high filtering capacity for tangential filtration (crossflow) applications, especially microfiltration, ultrafiltration applications. and nanofiltration. For the manufacture of the support, a single ceramic material, titanium oxide, is used, which allows the sintering temperature of the support to be reduced below 1500 ° C and since titanium oxide is a more chemically inert material, it allows to improve the resistance of the support against chemical attacks.
    The filtration membrane of the invention comprises a porous support with a titanium oxide main powder and a titanium oxide secondary powder, wherein the main powder has a particle size between 10-50 microns, and the secondary powder has a particle size at least 2 times less than the granulometry of the main powder, the granulometry of the secondary powder being greater than 5 microns, and where the main powder represents at least 50% by weight with respect to the total weight of the porous support.
    Additionally, the filtration membrane comprises one or more porous layers of ceramic material deposited on the porous support having a pore size between 1 and 1000 nm. The ceramic material of the porous layers is selected from the group consisting of AI2O3, TiO2, ZrO2 or SiO2.
    In this way a porous support is obtained that has advantageous properties for tangential filtration applications:
    • a pore size between 1 and 7 microns.
    • a percentage of porosity greater than 30%.
    • a mechanical resistance to bending at three points greater than or equal to 40 MPa.
    • a mechanical flexural strength greater than 35MP measured after a chemical attack with HNO3 with a concentration of 4% by weight at 70 ° C, or a chemical attack with NaOH with a concentration of 1.5% at 90 ° C.
    • a permeability with deionized water greater than or equal to 5000 l / hm2bar.
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    The addition of the secondary powder with a granulometry at least 2 times less than the granulometry of the main powder, but always greater than 5 microns, allows to control the pore size of the support maintaining a narrow pore size distribution, so that a porous support with a pore size between 1 and 7 microns, and a percentage of porosity greater than 30%, but without compromising the mechanical strength of the support, obtaining values of flexural strength at three points (MOR) higher or 10 equal at 40 MPa.
    On the other hand, using titanium oxide powder of different granulometry allows the area of contact between granules to be greater, since the granules of the secondary powder act as a bond between the granules of the main powder. Together with this, the greater thermal reactivity of the secondary powder favors the densification of the granules at lower sintering temperatures, below 1500 ° C and maintaining good mechanical qualities of the support. For all these reasons, an adequate selection of the granulometry of the titanium oxide powder with which the support is manufactured is essential to achieve adequate porosity and resistance characteristics.
    It should be borne in mind that with too low percentages of secondary dust, the pore size obtained increases generating pores that are too thick, and on the contrary, with the addition of too high amounts of secondary dust, the pore size is too thin to obtain adequate permeability in filtration processes. Therefore, the main powder must represent at least 50% by weight with respect to the total weight of porous support and preferably at least 70% by weight, so as to ensure a suitable pore size for microfiltration, ultrafiltration and nanofiltration (pore size of 1-7 microns).
    Thus, a filtration membrane is obtained which, due to its structural characteristics and chemical composition, results in high mechanical resistance and chemical stability, since in the manufacture of the support only titanium oxide is used in its composition, increasing its homogeneity and avoiding " impurities "that result in weak points from a mechanical and chemical point of view. In addition, the membranes have a high permeability due to the high percentage of porosity of the support and a narrow distribution of the pore size, due to the appropriate combination of different powder granulometry
    Description of the figures
    Figure 1 shows a perspective view of a filtration membrane with a tubular morphology.
    Figure 2 shows a longitudinal section view of the membrane of the previous figure.
    Figure 3 is a graph showing the pore size distribution of the porous support of the filtration membrane of the invention.
    Figure 4 is a graph showing the permeability with deionized water of the porous support of the filtration membrane of the invention.
    Detailed description of the invention
    Figure 1 shows the morphology of an example filtration membrane according to the invention. The filtration membrane comprises a porous support (1), made of a single ceramic material, and inner channels (2) through which the liquid to be filtered is circulated.
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    Figure 2 shows a cross section of the filtration membrane where the inner channels (2) are shown longitudinally. One or more porous layers of ceramic material (3) are deposited on the inner walls of said channels (2), which act as a semipermeable physical barrier capable of separating the substances contained in the liquid to be filtered by applying pressure and depending of its pore size. Thus, the greater proportion of the liquid continues through the inner channels (2) of the membrane, and substances with sizes smaller than the pore size of the layers of ceramic material (3) are filtered tangentially through the porous layers ( 3) and of the porous support itself (1), this filtered liquid being referred to as permeate.
    The filtration membrane has a tubular geometry with outside diameters between 8-80 mm and a length of up to 2000 mm. The membrane has a single-channel or multi-channel structure, up to 85 channels, with internal channel diameters between 1 and 10 mm.
    The porous support is made entirely of titanium oxide (TiO2) with a purity greater than 95%, and may include some traces of impurities due to the raw material used.
    The porous support is manufactured using titanium oxide of at least two different particle sizes. Thus, the porous support comprises a titanium oxide main powder having a granulometry between 10-50 microns and a secondary powder having a granulometry at least 2 times less than the granulometry of the main powder, the granulometry of the secondary powder being greater that 5 microns.
    For the manufacture of the porous support a ceramic paste is prepared with the titanium oxide powders of different granulometry, water, and other organic compounds such as plasticizers, binders or lubricants. After mixing and kneading the components, the ceramic paste is extruded to obtain a porous support, which can be single-channel or multi-channel depending on the nozzle used in the extrusion. The extruded "green" porous support is subjected to a heat treatment with a sintering temperature between 1200-1500 ° C.
    The porous layers of ceramic material (3) that are deposited on the inner channels (2) of the porous support (1) have a pore size between 1 and 1000 nm. The ceramic material from which the porous layers of ceramic material (3) are made is selected from the group consisting of aluminum oxide (AI2O3), titanium oxide (TiO2), zirconium oxide (ZrO2), or silicon oxide (SiO2 ).
    According to the present invention, because the size gradient of the different powder granules used is not very wide, the pore size distribution is also narrow, which favors a homogeneous adhesion of the layers deposited on the porous support. In addition, the use of main powder with a granulometry between 10 and 50 microns allows obtaining pore sizes of the support suitable for the deposition of the layers that give rise to microfiltration, ultrafiltration and nanofiltration membranes. Specifically, the average pore size obtained in the support of the invention is between 1 and 7 microns.
    By adjusting the sintering temperature to the distribution of the granulometry used in each case, high porosities above 30% are also obtained while maintaining a high mechanical resistance greater than 40 MPa in three-point flexural strength tests. The combination between the average pore size and its high porosity allows obtaining a high filtering capacity of the support, exceeding 5000 l / hm2bar in tests with deionized water.
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    The use of a single material in the composition of porous supports also favors resistance to acid and alkaline products used both in the filtration processes themselves and in chemical washes. Titanium oxide has a high resistance against chemical attacks, and given the high purity of porous supports (> 95%) and the non-presence of other compounds of different composition that act as weak points for these attacks, such as by For example, inorganic binders, the mechanical resistance of the supports is not compromised, staying above 35 MPa after attack with HN03 with a concentration of 4 wt% at 70 ° C or with NaOH with a concentration of 1.5 wt% at 90QC .
    According to a first embodiment of the invention, the porous support is manufactured using a main powder of a granulometry of 30 microns in a percentage of 70-80% and a secondary powder of a granulometry of 15 microns in a percentage of 20-30 %.
    The properties of the porous support obtained according to the first embodiment of the invention are shown in Table 1. The percentages of the powders used are expressed in percentage by weight (weight of the component in relation to the total weight of the ceramic composition of the porous support). The same table also shows the porosity (average pore size and percentage of porosity measured with the mercury intrusion porosimetry technique), the mechanical resistance before and after chemical attacks and the permeability with deionized water of the supports obtained .
    Table 1
    Ti02 with an average granule size of 30 microns [%] 70-80 Ti02 with an average granule size of 15 microns [%] 20-30 Average pore size [m] 4-6 Porosity [%] 30-40
    Flexural strength at three points (MOR) [MPa]> 45 MOR after HNO3 (4wt%) for 500 hours at 70 ° [MPa]> 35 MOR after NaOH (1.5wt%) for 500 hours at 90 ° C [ MPa]> 35 Permeability with deionized water [l / hm2bar]> 7000
    The pore size distribution of a porous support developed following the composition of the first embodiment of the invention is shown in Figure 3. In this case the average pore size obtained is between 4-6 microns, showing a narrow distribution.
    In Figure 4 the permeability curve of the support developed following the composition of the first embodiment of the invention can be observed, and it is observed that after 300 seconds of testing the permeability is maintained above 7500 l / hm2bar.
    According to a second embodiment of the invention, the porous support is manufactured using a main powder of a granulometry of 30 microns in a percentage of 85-90% and a secondary powder of a granulometry of 15 microns in a percentage of 10-15 %.
    The properties of the porous support obtained according to the second embodiment of the invention are shown in Table 2. As the properties of the porous support are observed
    they remain as high as in the porous support of the first embodiment of the invention, in which the percentage of porosity, mechanical strength and permeability corresponds, but as the percentage of secondary granules of smaller size decreases, the average size of the support pore.
    Table 2
    TiO2 with an average granule size of 30 microns [%] 85-90 TiO2 with an average granule size of 15 microns [%] 10-15 Average pore size [m] 6.5 - 7 Porosity [%] 30- 40
    Flexural strength at three points (MOR) [MPa]> 45 MOR after HNO3 (4wt%) for 500 hours at 70 ° [MPa]> 35 MOR after NaOH (1.5wt%) for 500 hours at 90 ° C [ MPa]> 35 Permeability with clean water [l / hm2bar]> 7000
    权利要求:
    Claims (6)
    [1]
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    1. High chemical resistance filtration membrane comprising a porous support with a titanium oxide main powder and a titanium oxide secondary powder, characterized in that the main powder has a particle size of between 10-50 microns, and the powder Secondary has a granulometry at least 2 times less than the granulometry of the main powder, the granulometry of the secondary powder being greater than 5 microns, and where the main powder represents at least 50% by weight with respect to the total weight of the porous support, such that the porous support has a pore size between 1 and 7 microns and a porosity percentage greater than 30%.
    [2]
    2. High chemical resistance filtration membrane according to the preceding claim,
    characterized in that the main titanium oxide powder represents at least 70% by weight with respect to the total weight of the porous support.
    [3]
    3. High chemical resistance filtration membrane, according to any one of the
    The preceding claims, characterized in that the titanium oxide support is sintered at a temperature between 1300-1500 ° C.
    [4]
    4. High chemical resistance filtration membrane, according to any one of the
    previous claims, characterized in that it additionally comprises one or more porous layers of ceramic material deposited on the porous support.
    [5]
    5. High chemical resistance filtration membrane according to the preceding claim,
    characterized in that the porous layers of ceramic material have a pore size between 1 and 1000 nm.
    [6]
    6. High chemical resistance filtration membrane according to claim 4 and 5,
    characterized in that the ceramic material of the porous layers is selected from the group consisting of AI2O3, TiO2, ZrO2 or SiO2.
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    同族专利:
    公开号 | 公开日
    ES2684634B1|2019-05-31|
    US20180280891A1|2018-10-04|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US5223318A|1990-08-06|1993-06-29|Corning Incorporated|Titania substrates and fabrication|
    EP0850680A1|1996-12-27|1998-07-01|Ngk Insulators, Ltd.|Ceramic porous membrane, ceramic porous body and method of manufacturing the membrane|
    US20030039774A1|2000-03-14|2003-02-27|Thomas Fleischmann|Method for producing monolithic, porous, ceramic shaped bodies and the shaped bodies produced according to this method|
    FR2575459B1|1984-12-28|1991-10-04|Commissariat Energie Atomique|PROCESS FOR THE MANUFACTURE OF POROUS AND PERMEABLE MINERAL MEMBRANES|
    EP0692303B1|1988-05-27|1999-01-27|Ngk Insulators, Ltd.|Process for the production of an inorganic porous composite membrane|
    FR2729584B1|1995-01-25|1997-08-01|Tami Ind|INORGANIC POROUS SUPPORT FOR MEMBRANE AND MANUFACTURING METHOD|
    FR3006606B1|2013-06-11|2015-07-03|Tech Avancees Et Membranes Industrielles|PROCESS FOR MANUFACTURING FILTRATION MEMBRANES BY ADDITIVE TECHNIQUE AND MEMBRANES OBTAINED|
    法律状态:
    2018-10-03| BA2A| Patent application published|Ref document number: 2684634 Country of ref document: ES Kind code of ref document: A1 Effective date: 20181003 |
    优先权:
    申请号 | 申请日 | 专利标题
    ES201700329A|ES2684634B1|2017-03-30|2017-03-30|Filtration membrane with high chemical resistance|ES201700329A| ES2684634B1|2017-03-30|2017-03-30|Filtration membrane with high chemical resistance|
    US15/940,093| US20180280891A1|2017-03-30|2018-03-29|Filtration membrane with high chemical resistance|
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