By a News Reporter-Staff News Editor at Life Science Weekly — According to news reporting originating from Alexandria, Virginia, by NewsRx journalists, a patent by the inventors Takagi, Mariko (Nagoya, JP); Noda, Kenichi (Nagoya, JP); Mori, Nobuhiko (Nagoya, JP); Kawai, Masaaki (Nagoya, JP); Satoh, Aya (Nagoya, JP), filed on December 27, 2012, was published online on July 1, 2014 (see also NGK Insulators, Ltd.).
The assignee for this patent, patent number 8764889, is NGK Insulators, Ltd. (Nagoya, JP).
Reporters obtained the following quote from the background information supplied by the inventors: “Upon separation or condensation of only a specific kind of substances out of a fluid where several kinds of substances are mixed together, a separation membrane may be used.
“The separation membrane has a structure having countless pores passing therethrough. Though various substances can generally be passed through the pores of the separation membrane, easiness of passing depends on the kind of substances. Therefore, in the case that substances easily passing through the pores of the separation membrane and substances hardly passing through the pores of the separation membrane are mixed together in substances contained in a fluid, by treating the fluid with the separation membrane, substances easily passing through the pores can pass through the separation membrane while substances hardly passing through the pores cannot pass through the separation membrane and remain as they are. Thus, treating a fluid with a separation membrane enables a specific kind of substances contained in the fluid to be separated or condensed.
“A silica membrane is a porous membrane having countless pores passing therethrough. Generally, the pores of a silica membrane are characterized by easily passing substances having small molecular diameters (e.g., water and carbon dioxide). Using this characteristic, a silica membrane is used for the case of separating water from a mixed liquid of water and ethanol, the case of separating carbon dioxide from a combustion exhaust gas, or the like (e.g., Patent Documents 1 to 5 and Non-Patent Documents 1 to 4). On the other hand, the pores of a conventional silica membrane are characterized by hardly passing an aromatic compound and alcohol having relatively large molecular diameters.”
In addition to obtaining background information on this patent, NewsRx editors also obtained the inventors’ summary information for this patent: “However, since a silica membrane is excellent in thermal resistance, chemical resistance, shock resistance, etc., it is demanded to become usable also in the case of separating an aromatic compound or an alcohol having relatively large molecular diameters.
“In view of the aforementioned problem, the objective of the present invention is to provide a silica membrane filter having performance of selectively separating an aromatic compound and performance of selectively separating an alcohol and a method for manufacturing the filter.
“The present invention is a silica membrane filter and a method for manufacturing the silica membrane filter described below.
“[1] A silica membrane filter comprising a porous substrate and a silica membrane provided on a surface of the porous substrate, wherein the ratio of a He gas permeation amount to an N.sub.2 gas permeation amount (He gas permeation amount/N.sub.2 gas permeation amount) is 7 or less, and the ratio of the N.sub.2 gas permeation amount to a SF.sub.6 gas permeation amount (N.sub.2 gas permeation amount/SF.sub.6 gas permeation amount) is 1.5 or more.
“[2] The silica membrane filter according to [1], wherein the ratio of the He gas permeation amount to the N.sub.2 gas permeation amount (He gas permeation amount/N.sub.2 gas permeation amount) is 1.0 to 2.6, and the ratio of the N.sub.2 gas permeation amount to the SF.sub.6 gas permeation amount (N.sub.2 gas permeation amount/SF.sub.6 gas permeation amount) is 1.5 to 10.
“[3] The silica membrane filter according to [1] or [2], wherein the silica membrane contains an aryl group.
“[4] The silica membrane filter according to [3], wherein the aryl group of the silica membrane is one of a phenyl group, a benzyl group, a tolyl group, and a xylyl group.
“[5] The silica membrane filter according to [4], wherein the ratio of the N.sub.2 gas permeation amount to the SF.sub.6 gas permeation amount (N.sub.2 gas permeation amount/SF.sub.6 gas permeation amount) is 3.0 to 10.
“[6] The silica membrane filter according to [1] or [2], wherein the silica membrane contains an alkyl group.
“[7] The silica membrane filter according to [6], wherein the alkyl group has a carbon number of 2 to 8.
“[8] The silica membrane filter according to [7], wherein the ratio of the N.sub.2 gas permeation amount to the SF.sub.6 gas permeation amount (N.sub.2 gas permeation amount/SF.sub.6 gas permeation amount) is 1.5 to 5.0.
“[9] The silica membrane filter according to [1] or [2], which can be obtained by subjecting a precursor sol made of a silica raw material containing a silica compound containing an aryl group and/or an alkyl group to a thermal treatment.
“[10] The silica membrane filter according to [9], wherein the silica compound contains an alkoxysilane containing an aryl group and/or an alkyl group.
“[11] The silica membrane filter according to [9] or [10], wherein a part of the aryl group and/or the alkyl group derived from the silica compound is decomposed by the thermal treatment.
“[12] The silica membrane filter according to [11], wherein 40 to 99% of the aryl group and/or the alkyl group derived from the silica compound is decomposed.
“[13] The silica membrane filter according to any one of [1] to [12], wherein the N.sub.2 gas permeation amount is 5.0.times.10.sup.-9 mol/m.sup.2Pas or more.
“[14] A method for manufacturing a silica membrane filter comprising: a precursor solution preparation step of subjecting a silica compound to hydrolysis and polycondensation to obtain a precursor solution containing a precursor sol, a coating step of bringing the precursor solution into contact with a surface of a porous substrate and allowing the precursor sol contained in the precursor solution to adhere to the surface of the porous substrate by the flow of the precursor solution due to its own weight, and a drying and thermal treatment step of drying the precursor sol adhering to the surface of the porous substrate and then thermally treating the dried precursor sol at 300 to 600.degree. C.
“[15] The method for manufacturing a silica membrane filter according to [14], wherein a part of or all the silica compound is a silica compound containing an aryl group and/or an alkyl group.
“[16] The method for manufacturing a silica membrane filter according to [15], wherein a part of or all the silica compound is an alkoxysilane containing an aryl group and/or an alkyl group.
“A silica membrane filter of the present invention has performance of selectively separating an aromatic compound and performance of selectively separating an alcohol. A method for manufacturing a silica membrane filter of the present invention enables to obtain a silica membrane filter having performance of selectively separating an aromatic compound and performance of selectively separating an alcohol.”
For more information, see this patent: Takagi, Mariko; Noda, Kenichi; Mori, Nobuhiko; Kawai, Masaaki; Satoh, Aya. Silica Film Filter and Process for Producing Silica Film Filter. U.S. Patent Number 8764889, filed December 27, 2012, and published online on July 1, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8764889.PN.&OS=PN/8764889RS=PN/8764889
Keywords for this news article include: Chemicals, Chemistry, Carbon Dioxide, NGK Insulators Ltd.
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