JP7571646B2 - Sodium ferrite particles and method for producing same - Google Patents
Sodium ferrite particles and method for producing same Download PDFInfo
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- 239000011734 sodium Substances 0.000 title claims description 132
- 229910052708 sodium Inorganic materials 0.000 title claims description 111
- 229910000859 α-Fe Inorganic materials 0.000 title claims description 98
- 239000002245 particle Substances 0.000 title claims description 95
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 title claims description 91
- 238000004519 manufacturing process Methods 0.000 title claims description 12
- 239000000843 powder Substances 0.000 claims description 67
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 40
- 239000013078 crystal Substances 0.000 claims description 23
- 239000002184 metal Substances 0.000 claims description 21
- 229910052751 metal Inorganic materials 0.000 claims description 21
- 239000011164 primary particle Substances 0.000 claims description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 15
- 150000002739 metals Chemical class 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 238000003746 solid phase reaction Methods 0.000 claims description 12
- 239000002994 raw material Substances 0.000 claims description 11
- 229910052709 silver Inorganic materials 0.000 claims description 11
- 239000004332 silver Substances 0.000 claims description 11
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 10
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 9
- 229910052802 copper Inorganic materials 0.000 claims description 9
- 239000010949 copper Substances 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 5
- 239000006104 solid solution Substances 0.000 claims description 5
- 239000011817 metal compound particle Substances 0.000 claims description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 236
- 239000001569 carbon dioxide Substances 0.000 description 118
- 229910002092 carbon dioxide Inorganic materials 0.000 description 118
- 239000012071 phase Substances 0.000 description 28
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 24
- 239000000463 material Substances 0.000 description 18
- 238000011084 recovery Methods 0.000 description 18
- 239000007789 gas Substances 0.000 description 16
- 238000006243 chemical reaction Methods 0.000 description 14
- 239000003973 paint Substances 0.000 description 14
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 12
- 238000003795 desorption Methods 0.000 description 9
- 238000010438 heat treatment Methods 0.000 description 9
- 239000007787 solid Substances 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 150000001412 amines Chemical class 0.000 description 8
- 235000011121 sodium hydroxide Nutrition 0.000 description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 239000001301 oxygen Substances 0.000 description 7
- 229910052760 oxygen Inorganic materials 0.000 description 7
- 229910000029 sodium carbonate Inorganic materials 0.000 description 6
- 235000017550 sodium carbonate Nutrition 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- 238000002485 combustion reaction Methods 0.000 description 5
- 229910010272 inorganic material Inorganic materials 0.000 description 5
- 239000011147 inorganic material Substances 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 238000001179 sorption measurement Methods 0.000 description 5
- 229910021314 NaFeO 2 Inorganic materials 0.000 description 4
- 239000006227 byproduct Substances 0.000 description 4
- 238000001879 gelation Methods 0.000 description 4
- 239000005431 greenhouse gas Substances 0.000 description 4
- 231100001261 hazardous Toxicity 0.000 description 4
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 4
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Chemical compound [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 description 4
- 239000002250 absorbent Substances 0.000 description 3
- 230000002745 absorbent Effects 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 239000000383 hazardous chemical Substances 0.000 description 3
- 238000010671 solid-state reaction Methods 0.000 description 3
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000010669 acid-base reaction Methods 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 238000005273 aeration Methods 0.000 description 2
- 229910052788 barium Inorganic materials 0.000 description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
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- 238000000921 elemental analysis Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 239000002803 fossil fuel Substances 0.000 description 2
- 239000000295 fuel oil Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000011019 hematite Substances 0.000 description 2
- 229910052595 hematite Inorganic materials 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- JXGGISJJMPYXGJ-UHFFFAOYSA-N lithium;oxido(oxo)iron Chemical compound [Li+].[O-][Fe]=O JXGGISJJMPYXGJ-UHFFFAOYSA-N 0.000 description 2
- 150000002736 metal compounds Chemical class 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000000634 powder X-ray diffraction Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000011002 quantification Methods 0.000 description 2
- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 235000010288 sodium nitrite Nutrition 0.000 description 2
- 229910001948 sodium oxide Inorganic materials 0.000 description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 description 2
- 235000011152 sodium sulphate Nutrition 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 238000004876 x-ray fluorescence Methods 0.000 description 2
- 238000004438 BET method Methods 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- IOVCWXUNBOPUCH-UHFFFAOYSA-N Nitrous acid Chemical compound ON=O IOVCWXUNBOPUCH-UHFFFAOYSA-N 0.000 description 1
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical group [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 150000003973 alkyl amines Chemical class 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003502 gasoline Substances 0.000 description 1
- 229910052598 goethite Inorganic materials 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- AEIXRCIKZIZYPM-UHFFFAOYSA-M hydroxy(oxo)iron Chemical compound [O][Fe]O AEIXRCIKZIZYPM-UHFFFAOYSA-M 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- LLHKCFNBLRBOGN-UHFFFAOYSA-N propylene glycol methyl ether acetate Chemical compound COCC(C)OC(C)=O LLHKCFNBLRBOGN-UHFFFAOYSA-N 0.000 description 1
- 238000013341 scale-up Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 229910001923 silver oxide Inorganic materials 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 239000011029 spinel Substances 0.000 description 1
- 229910052596 spinel Inorganic materials 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000011232 storage material Substances 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 238000002411 thermogravimetry Methods 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 238000004056 waste incineration Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Landscapes
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Carbon And Carbon Compounds (AREA)
- Compounds Of Iron (AREA)
Description
本発明は、二酸化炭素を固定化するナトリウムフェライト粒子粉末及びその製造方法を提供するものである。 The present invention provides sodium ferrite particles that immobilize carbon dioxide and a method for producing the same.
気候変動枠組条約（パリ条約）は、世界全体の平均気温の上昇を２℃より十分下方に抑えるべく、その原因とされる温室効果ガス排出の実質ゼロを目標にして、２０１５年に策定された。その中で、政府方針としては、２０３０年までに２０１３年度対比２６％の温室効果ガスの削減を中期目標として掲げている。温室効果ガスの主体は化石燃料の燃焼によって発生する二酸化炭素である。１９５０年代の大気中の二酸化炭素濃度は約３００ｐｐｍであるのに対し、近年４００ｐｐｍを超えたことが報告されている。大気中への二酸化炭素の放出量の削減の切り札として、二酸化炭素の回収、貯蔵、及びその回収利用の研究が進められている。 The United Nations Framework Convention on Climate Change (Paris Convention) was established in 2015 with the goal of reducing greenhouse gas emissions, which are believed to be the cause of the rise in global average temperature, to virtually zero in order to keep the increase well below 2 degrees Celsius. In this treaty, the government has set a mid-term goal of reducing greenhouse gas emissions by 26% by 2030 compared to fiscal 2013 levels. The main greenhouse gas is carbon dioxide, which is generated by the combustion of fossil fuels. The carbon dioxide concentration in the atmosphere was approximately 300 ppm in the 1950s, but it has been reported to have exceeded 400 ppm in recent years. Research is being conducted into the capture, storage, and utilization of carbon dioxide as a trump card for reducing the amount of carbon dioxide released into the atmosphere.
二酸化炭素の大規模発生源としては、各所から化石燃料の燃焼により発生する排ガス放出口である。石炭、重油、天然ガスなどを燃料とする火力発電所、製造所のボイラー、及びセメント工場のキルンなどが挙げられる。また、コークスで酸化鉄を還元する製鉄所の高炉、または、ガソリン、重油、軽油を燃料とする自動車、船舶、及び航空機などの輸送機から排出される二酸化炭素がある。 Large-scale sources of carbon dioxide include exhaust gas outlets generated by the burning of fossil fuels. Examples include thermal power plants that use coal, heavy oil, or natural gas as fuel, boilers in manufacturing plants, and kilns in cement plants. Other sources of carbon dioxide include blast furnaces in steelworks that reduce iron oxide with coke, and carbon dioxide emitted from transportation vehicles such as automobiles, ships, and airplanes that use gasoline, heavy oil, or diesel as fuel.
現在、火力発電所などの大規模施設では、排ガスをアルカノールアミンなどのアミン水溶液と接触させて、排ガス中に含まれる二酸化炭素を吸収させている。また、その後、１２０℃程度に加熱して、吸収した二酸化炭素を回収する。これらの試みは大々的に開始され、大きな効果を上げている（特許文献１～２）。この方法は、液体による吸収材を用いるため、吸収材をポンプで移送できるという利点を有する。そのため、大型化がしやすい。アミン系二酸化炭素回収材は火力発電所、製鉄所などで実用化されつつある。 Currently, in large-scale facilities such as thermal power plants, exhaust gas is brought into contact with an aqueous amine solution such as alkanolamine to absorb the carbon dioxide contained in the exhaust gas. The gas is then heated to about 120°C to capture the absorbed carbon dioxide. These attempts have been launched on a large scale and have produced great results (Patent Documents 1 and 2). This method has the advantage that a liquid absorbent is used, making it possible to transport the absorbent with a pump. This makes it easy to scale up the system. Amine-based carbon dioxide capture materials are beginning to be put to practical use in thermal power plants, steelworks, and other facilities.
しかしながら、この方法は、危険物の液体を用いるため、日本の１８００箇所以上存在するゴミ焼却場などの中小施設では、危険物液体の運用がしづらい。その結果、二酸化炭素の固定化及び回収はほとんどされていないのが現状である。現在、日本全体の二酸化炭素の総排出量は微減傾向である。そこで、前記中小施設でも二酸化炭素を固定化及び回収することができるように扱いが容易で、アミンなどの危険物を伴わない安価な固体による二酸化炭素の固定化及び回収が期待されるところである。 However, this method uses a hazardous liquid, which makes it difficult to handle in small and medium-sized facilities such as waste incineration plants, of which there are over 1,800 in Japan. As a result, carbon dioxide fixation and capture is currently rare. At present, the total amount of carbon dioxide emissions throughout Japan is showing a slight downward trend. Therefore, it is hoped that carbon dioxide fixation and capture will be possible using an inexpensive solid that is easy to handle and does not involve hazardous materials such as amines, so that even small and medium-sized facilities can fix and capture carbon dioxide.
これまでに、固体による二酸化炭素の固定回収材としては前述のアルカノールアミンを担持した固体（特許文献３）、または、オルソチタン酸バリウム（特許文献４）、リチウムフェライト（特許文献５）が知られている。 So far, known solid carbon dioxide capture materials include the aforementioned alkanolamine-supported solid (Patent Document 3), barium orthotitanate (Patent Document 4), and lithium ferrite (Patent Document 5).
ナトリウムフェライト（特許文献６、非特許文献１、２）もまた二酸化炭素の固定回収材として知られている。中でも層状岩塩構造（三方晶系）のα－ナトリウムフェライトは二酸化炭素とナトリウムがトポケミカル的に反応する。即ち、二酸化炭素との反応中α－ナトリウムフェライトは、Ｎａ１－ｘＦｅＯ２と炭酸ナトリウムの混合相となる。そのため、該反応速度は高く、且つ該反応による二酸化炭素の吸放出繰り返し性能は優れているとの報告がある。一方、斜方晶系のβ－ナトリウムフェライトはナトリウムと二酸化炭素が反応するため、β－ナトリウムフェライトの結晶相はα－ナトリウムフェライトの結晶相に比べ、二酸化炭素の吸収量が多いことが報告されている。 Sodium ferrite (Patent Document 6, Non-Patent Documents 1 and 2) is also known as a material for capturing and storing carbon dioxide. In particular, in the case of α-sodium ferrite with a layered rock salt structure (trigonal crystal system), carbon dioxide and sodium react topochemically. That is, during the reaction with carbon dioxide, α-sodium ferrite becomes a mixed phase of Na 1-x FeO 2 and sodium carbonate. Therefore, it has been reported that the reaction rate is high and the repeated absorption and release performance of carbon dioxide due to the reaction is excellent. On the other hand, in the case of orthorhombic β-sodium ferrite, sodium and carbon dioxide react with each other, so it has been reported that the crystal phase of β-sodium ferrite absorbs more carbon dioxide than the crystal phase of α-sodium ferrite.
一般に、ナトリウムフェライトが二酸化炭素と反応する式としては、気体に水蒸気を含まない場合は、ＮａＦｅＯ２＋１／２ＣＯ２→１／２Ｎａ２ＣＯ３＋１／２Ｆｅ２Ｏ３、水蒸気を含む場合は、ＮａＦｅＯ２＋ＣＯ２＋１／２Ｈ２Ｏ→ＮａＨＣＯ３＋１／２Ｆｅ２Ｏ３と記載することができる。そのため、ナトリウムフェライトに対して、理論上、最大１８～３０重量％の二酸化炭素を吸着、脱離できる能力を持つ。 In general, the reaction equation of sodium ferrite with carbon dioxide can be expressed as follows when the gas does not contain water vapor: NaFeO 2 + 1/2CO 2 → 1/2Na 2 CO 3 + 1/2Fe 2 O 3 , and when water vapor is contained: NaFeO 2 + CO 2 + 1/2H 2 O → NaHCO 3 + 1/2Fe 2 O 3. Therefore, sodium ferrite has the theoretical ability to adsorb and desorb a maximum of 18 to 30% by weight of carbon dioxide.
これまで述べてきたように、固体、特に非危険物の無機材料による二酸化炭素の固定回収材が期待されているところである。ただ、現行のアミン水溶液による二酸化炭素の固定回収が１２０℃程度で行われるのに対し、オルソチタン酸バリウム（特許文献４）やリチウムフェライト（特許文献５）等の無機材料による二酸化炭素の固定回収材は、２００℃以上の温度領域で二酸化炭素の吸脱着が行われており、エネルギーコストとしてアミン水溶液を用いるものに劣るものであった。 As mentioned above, there are high hopes for carbon dioxide fixation and capture materials using solid, particularly non-hazardous inorganic materials. However, while the current fixation and capture of carbon dioxide using an amine aqueous solution is carried out at around 120°C, carbon dioxide fixation and capture materials using inorganic materials such as barium orthotitanate (Patent Document 4) and lithium ferrite (Patent Document 5) adsorb and desorb carbon dioxide in a temperature range of 200°C or higher, which is inferior in terms of energy costs to those using an amine aqueous solution.
即ち、前記特許文献１、２に記載のものは、アミン水溶液を二酸化炭素の固定回収材として用いており、火力発電所などの大型施設では有利ではあるが、中小の二酸化炭素を排出する施設には適していないものであった。 That is, the methods described in Patent Documents 1 and 2 use an amine aqueous solution as a material for capturing and fixing carbon dioxide, which is advantageous for large facilities such as thermal power plants, but is not suitable for small and medium-sized facilities that emit carbon dioxide.
前記特許文献３に記載のものもまた、アルカノールアミンを含有する二酸化炭素の固定回収材であり、危険物のアルカノールアミンを用いる。そのため、アミン成分の溶出などが懸念されるため、中小の施設には適していないものであった。 The material described in Patent Document 3 is also a carbon dioxide capture material that contains alkanolamine, and uses alkanolamine, which is a hazardous substance. Therefore, there are concerns about the leaching of the amine components, and it is not suitable for small and medium-sized facilities.
前記特許文献４に記載のものは、二酸化炭素の固定回収材として、Ｂａ２ＴｉＯ４系複合酸化物を用いている。しかしながら、二酸化炭素の放出工程における加熱温度が８００～１０００℃であるため、熱コストとして不利なものであった。 The method described in Patent Document 4 uses a Ba2TiO4 - based composite oxide as a carbon dioxide capture material. However, the heating temperature in the carbon dioxide release step is 800 to 1000°C, which is disadvantageous in terms of heat cost.
前記特許文献５に記載のものは、二酸化炭素の固定回収材として、リチウム及び鉄を含有する複合酸化物を用いている。しかしながら、二酸化炭素の固定回収温度が５００℃で、放出温度が７００℃のため、熱コストとして不利なものであった。 The system described in Patent Document 5 uses a composite oxide containing lithium and iron as a carbon dioxide capture material. However, the carbon dioxide capture temperature is 500°C, and the release temperature is 700°C, which is disadvantageous in terms of heat costs.
前記特許文献６、及び非特許文献１、２に記載のものは、室温における二酸化炭素の固定回収が報告されており、また、多孔質体に関する報告もされている。しかしながら、材料そのものの成形性や加工性に関する記述は存在しなかった。 The above-mentioned Patent Document 6 and Non-Patent Documents 1 and 2 report the fixation and recovery of carbon dioxide at room temperature, and also report on porous bodies. However, there is no description of the moldability or processability of the material itself.
そこで、本発明は、二酸化炭素を室温から１００℃までの温度範囲で固定化し、１５０℃以下の加熱で二酸化炭素を回収でき、且つ成形性や加工性に富んだナトリウムフェライト粒子粉末を提供すること、及び該粒子粉末の製造方法を提供することを目的とする。 Therefore, the present invention aims to provide sodium ferrite particles that can immobilize carbon dioxide in the temperature range from room temperature to 100°C, recover carbon dioxide by heating at 150°C or less, and have excellent moldability and processability, and to provide a method for producing the particles.
前記の目的を達成するために、本発明者らは、鋭意研究の結果、所定の物性及び組成比を有するナトリウムフェライト粒子粉末を用いることにより、二酸化炭素を室温から１００℃までの温度範囲で固定化し、１５０℃以下で固定化した二酸化炭素を回収できることを見出して本発明を完成した。 In order to achieve the above object, the inventors conducted extensive research and discovered that by using sodium ferrite particle powder having the specified physical properties and composition ratio, carbon dioxide can be immobilized in the temperature range from room temperature to 100°C, and the immobilized carbon dioxide can be recovered at 150°C or less, thus completing the present invention.
具体的に、本発明に係るナトリウムフェライト粒子粉末は、銅及び銀からなる１価金属群より選ばれた少なくとも１種類以上の金属が、固溶、または、特定の結晶形態を示さない状態で、酸化物換算として０．０５～５重量％存在し、Ｎａ／Ｆｅのモル比が０．７５～１．２５であることを特徴とする。 Specifically, the sodium ferrite particles according to the present invention are characterized in that at least one metal selected from the group of monovalent metals consisting of copper and silver is present in an amount of 0.05 to 5% by weight, calculated as oxide, in a state in which the metal is in a solid solution or does not show a specific crystal form, and the molar ratio of Na/Fe is 0.75 to 1.25.
前記金属が、生成するナトリウムフェライトに固溶または粒子表面に特定の結晶形態を示さない状態で存在することで、純粋なナトリウムフェライトよりも、低い温度で固定化した二酸化炭素を回収することが可能となっている。詳細は明らかではないが、これは、それらの金属成分の存在により、二酸化炭素を取り込んだＮａ１－ｘＦｅＯ２と炭酸ナトリウムの混合相から、より低いエネルギー付与で二酸化炭素を揮発させる、または、より低いエネルギー付与でナトリウムフェライトに戻る触媒作用を起こしているものと考えられる。また、本発明に係る粒子粉末では、Ｎａ／Ｆｅのモル比が０．７５～１．２５であるため、ナトリウムフェライト結晶相を多く含むことができて、二酸化炭素の固定回収性能が良好となり、Ｎａの割合が過剰に多くないため、粒子粉末を塗料化した際の塗料のゲル化の原因となる副生成物のＮａＯＨやＮａ２ＣＯ３等のアルカリ成分も残存しにくくなるため、高分散性の塗料となり得る。これらの特性が相まって、本発明に係るナトリウムフェライト粒子粉末によると、二酸化炭素を室温から１００℃までの温度範囲で固定化し、１５０℃以下で固定化した二酸化炭素を回収できる。 The metals are present in the sodium ferrite produced in a state of solid solution or not showing a specific crystal form on the particle surface, so that it is possible to recover the fixed carbon dioxide at a lower temperature than pure sodium ferrite. Although the details are not clear, it is considered that the presence of these metal components causes the mixed phase of Na 1-x FeO 2 and sodium carbonate that has taken in carbon dioxide to volatilize with less energy applied, or causes a catalytic action that returns to sodium ferrite with less energy applied. In addition, since the particle powder according to the present invention has a molar ratio of Na/Fe of 0.75 to 1.25, it can contain a large amount of sodium ferrite crystal phase, and the fixed recovery performance of carbon dioxide is good, and since the proportion of Na is not excessively high, alkaline components such as NaOH and Na 2 CO 3 , which are by-products that cause gelation of the paint when the particle powder is made into a paint, are less likely to remain, so that it can become a highly dispersible paint. With these characteristics combined, the sodium ferrite particle powder according to the present invention can fix carbon dioxide at a temperature range from room temperature to 100°C and recover the fixed carbon dioxide at 150°C or less.
本発明に係るナトリウムフェライト粒子粉末は、一次粒子の平均短軸径に対する平均長軸径の軸比が１～２であることが好ましい。 The sodium ferrite particles according to the present invention preferably have an axial ratio of the average major axis diameter to the average minor axis diameter of the primary particles of 1 to 2.
前記粒子粉末は、一次粒子の平均短軸径に対する平均長軸径の軸比が１～２と小さく球形に近い形状であるため、分散性が高く、一次粒子が凝集しにくくなり、成形性や加工性に優れた粒子粉末とすることができる。 The particle powder has a small axial ratio of the average major axis diameter to the average minor axis diameter of the primary particles of 1 to 2, and has a shape close to a sphere, so it has high dispersibility, the primary particles are less likely to aggregate, and it can be made into a particle powder with excellent moldability and processability.
本発明に係るナトリウムフェライト粒子粉末は、粉体ｐＨ値が８～１４であることが好ましい。 The sodium ferrite particles according to the present invention preferably have a powder pH value of 8 to 14.
粉体ｐＨ値が８～１４であれば、本発明に係るナトリウムフェライト粒子粉末は塩基性であるため、弱酸性である二酸化炭素を捉えやすくなる。さらに、上述の通り、塗料のゲル化の原因となる副生成物のＮａＯＨやＮａ２ＣＯ３等のアルカリ成分が残存しにくくなるため、高い分散性を有する塗料として利用することもできる。 If the powder pH value is 8 to 14, the sodium ferrite particles according to the present invention are basic and therefore easily capture carbon dioxide, which is weakly acidic. Furthermore, as described above, the by-products such as NaOH and Na2CO3 , which cause gelation of the paint, are less likely to remain, so that the particles can be used as a paint having high dispersibility.
本発明に係るナトリウムフェライト粒子粉末の製造方法は、銅及び銀からなる１価金属群より選ばれた少なくとも１種類以上の金属化合物粒子粉末、酸化鉄粒子粉末及びナトリウム原料の粒子粉末を混合して、１５０～４００℃の温度で水蒸気固相反応するステップを含むことを特徴とする。 The method for producing sodium ferrite particles according to the present invention is characterized by comprising the steps of mixing at least one metal compound powder selected from a group of monovalent metals consisting of copper and silver, iron oxide powder, and sodium raw material powder, and subjecting the mixture to a water vapor solid-phase reaction at a temperature of 150 to 400°C.
本発明に係るナトリウムフェライト粒子粉末の製造方法では、固体と固体を混合し、溶媒を介さず元素を移動させて反応させており、反応母液としての溶媒を用いないため、液相反応に用いた場合の溶媒などの廃棄物を抑えることができる。特に、低温での固相反応の場合、極めて高濃度反応となり得るため、エネルギーコストを低く抑えることができる。さらに水蒸気による加熱により、酸化鉄とナトリウム源との接触界面に微量の水分が介在することにより、接触界面の酸塩基反応が促進される。また、水蒸気により、酸素分圧が低くなるため、副反応である酸化鉄の酸化反応が抑制され、純度が上がりやすい。さらに、水蒸気加熱により発火の危険性が著しく低下する。従って、発明に係るナトリウムフェライト粒子粉末の製造方法によると、二酸化炭素を室温から１００℃までの温度範囲で固定化し、１５０℃以下の加熱で二酸化炭素を回収でき、且つ成形性や加工性に富んだナトリウムフェライト粒子粉末を高純度且つ高効率で製造することができる。 In the method for producing sodium ferrite particles according to the present invention, solids are mixed and reacted by transferring elements without the aid of a solvent. Since no solvent is used as the reaction mother liquid, waste such as solvents that would be generated in a liquid-phase reaction can be reduced. In particular, in the case of a solid-phase reaction at low temperatures, a very high-concentration reaction can be achieved, so energy costs can be kept low. Furthermore, heating with water vapor promotes an acid-base reaction at the contact interface between the iron oxide and the sodium source by introducing a small amount of moisture into the contact interface. In addition, the oxygen partial pressure is reduced by the water vapor, so that the oxidation reaction of the iron oxide, which is a side reaction, is suppressed, and the purity is easily increased. Furthermore, the risk of fire is significantly reduced by heating with water vapor. Therefore, according to the method for producing sodium ferrite particles according to the present invention, carbon dioxide can be fixed in a temperature range from room temperature to 100°C, carbon dioxide can be recovered by heating at 150°C or less, and sodium ferrite particles with excellent moldability and processability can be produced with high purity and high efficiency.
本発明に係るナトリウムフェライト粒子粉末は、非危険物の無機材料にて、二酸化炭素を室温から１００℃までの温度範囲で固定化し、１５０℃以下で固定化した二酸化炭素を回収できる。また、前記粒子粉末は塗料化後、分散性に優れるため、成形性及び加工性に優れた材料として好適である。 The sodium ferrite particle powder according to the present invention is a non-hazardous inorganic material that can immobilize carbon dioxide at temperatures ranging from room temperature to 100°C and recover the immobilized carbon dioxide at temperatures below 150°C. In addition, the particle powder has excellent dispersibility after being made into a paint, making it suitable as a material with excellent moldability and processability.
本発明の構成をより詳しく説明すれば次の通りである。 The configuration of the present invention is explained in more detail as follows:
先ず、本発明の一実施形態に係る二酸化炭素の固定回収材について述べる。 First, we will describe a carbon dioxide capture and storage material according to one embodiment of the present invention.
本実施形態に係るナトリウムフェライト粒子粉末は、銅及び銀からなる１価金属群より選ばれた１種類以上の金属が酸化物換算として０．０５～５重量％含有する。前記重量％の範囲の場合、二酸化炭素の固定回収性能を高めることができる。より好ましくは、前記重量％の範囲は０．１～５．０重量％である。 The sodium ferrite particles according to this embodiment contain 0.05 to 5% by weight, calculated as oxide, of one or more metals selected from the group of monovalent metals consisting of copper and silver. When the weight percentage is within this range, the carbon dioxide fixation and recovery performance can be improved. More preferably, the weight percentage range is 0.1 to 5.0% by weight.
本発明の一実施形態に係るナトリウムフェライト粒子粉末は、Ｎａ／Ｆｅのモル比が０．７５～１．２５である。Ｎａ／Ｆｅのモル比が０．７５未満であれば、生成するナトリウムフェライト粒子の含有量が少ない粉末となり、二酸化炭素の固定回収性能に劣るものとなる。また、Ｎａ／Ｆｅのモル比が１．２５を超えると、副生成物のＮａＯＨやＮａ２ＣＯ３等のアルカリ成分が多く残存する。該アルカリ成分は塗料のゲル化の原因でも有り、高分散性の塗料ができるとは言い難く、成形性及び加工性に優れた粒子粉末とは言い難くなる。好ましくは、Ｎａ／Ｆｅのモル比が０．８０～１．２０であり、より好ましくは０．９０～１．１０である。 The sodium ferrite particles according to one embodiment of the present invention have a molar ratio of Na/Fe of 0.75 to 1.25. If the molar ratio of Na/Fe is less than 0.75, the resulting powder will have a low content of sodium ferrite particles, and will have poor carbon dioxide fixation and recovery performance. If the molar ratio of Na/Fe exceeds 1.25, a large amount of alkaline components such as by-products NaOH and Na 2 CO 3 will remain. These alkaline components are also the cause of gelation of paint, and it is difficult to say that a highly dispersible paint can be produced, and it is difficult to say that the resulting particle powder has excellent moldability and processability. Preferably, the molar ratio of Na/Fe is 0.80 to 1.20, more preferably 0.90 to 1.10.
本発明の一実施形態に係るナトリウムフェライト粒子粉末は、α－ナトリウムフェライトの結晶相が９８重量％以上含まれることが好ましい。α－ナトリウムフェライト結晶を有する化合物は、鉄、酸素、ナトリウムが層状に配置される層状化合物であり、該層に平行な酸素六方格子が・・・ＡＢＣＡＢＣ・・・のパターンで並んでいる。前記酸素六方格子間のナトリウムイオンがα－ナトリウムフェライト粒子表面に移動して二酸化炭素と反応する。そのため、この反応は、α－ナトリウムフェライト粒子形状を維持したままのトポケミカル的な反応と言われている。α－ナトリウムフェライトの結晶相をより多く含んでいると、二酸化炭素の固定回収の繰り返し性能に優れるため、好ましい。より好ましくは、α－ナトリウムフェライトの結晶相の含有量が９９重量％以上である。 The sodium ferrite particle powder according to one embodiment of the present invention preferably contains 98% by weight or more of the crystalline phase of α-sodium ferrite. The compound having α-sodium ferrite crystals is a layered compound in which iron, oxygen, and sodium are arranged in layers, and oxygen hexagonal lattices parallel to the layers are arranged in a pattern of ...ABCABC.... The sodium ions between the oxygen hexagonal lattices move to the surface of the α-sodium ferrite particles and react with carbon dioxide. Therefore, this reaction is said to be a topochemical reaction in which the shape of the α-sodium ferrite particles is maintained. It is preferable to contain a larger amount of the crystalline phase of α-sodium ferrite, since this provides excellent repeatability in the fixation and recovery of carbon dioxide. More preferably, the content of the crystalline phase of α-sodium ferrite is 99% by weight or more.
本実施形態に係るナトリウムフェライト粒子粉末は、β－ナトリウムフェライトの結晶相が２重量％以下であることが好ましい。β－ナトリウムフェライトの結晶相は酸素六方格子が・・・ＡＢＡＢＡＢ・・・のパターンで並んでいる。また、β－ナトリウムフェライトの１モル当りの体積はα－ナトリウムフェライトに比べ１．３倍と高く、原子間の結合強度も弱いことが予想され、結晶構造が崩壊しやすいことも予期される。そのため、β－ナトリウムフェライトの結晶相が２重量％を超えると二酸化炭素繰り返し性能の点で好ましくない。 The sodium ferrite particle powder according to this embodiment preferably contains 2% by weight or less of the β-sodium ferrite crystal phase. The β-sodium ferrite crystal phase has an oxygen hexagonal lattice arranged in an ...ABABAB... pattern. In addition, the volume per mole of β-sodium ferrite is 1.3 times higher than that of α-sodium ferrite, and the bond strength between atoms is expected to be weak, and the crystal structure is expected to easily collapse. Therefore, if the β-sodium ferrite crystal phase exceeds 2% by weight, it is not preferable in terms of carbon dioxide repeatability.
本実施形態に係るナトリウムフェライト粒子粉末は、未反応生成相であるマグネタイト相、または、マグへマイト相が２重量％以下であることが好ましい。未反応生成相が増えると二酸化炭素回収性能が落ちるため好ましくない。 The sodium ferrite particles according to this embodiment preferably contain 2% by weight or less of the unreacted magnetite phase or maghemite phase. An increase in the unreacted phase is undesirable because it reduces the carbon dioxide capture performance.
本実施形態に係るナトリウムフェライト粒子粉末は、粉体ｐＨが８～１４であることが好ましい。粉体ｐＨが８以上の塩基性であることにより、弱酸性である二酸化炭素を捉えやすい。一方、粉体ｐＨが１４を越えると塗料のゲル化が生じ、高分散性とは成り難い。より好ましくは粉体ｐＨが８．２～１３．５である。 The sodium ferrite particle powder according to this embodiment preferably has a powder pH of 8 to 14. By having a powder pH of 8 or more, which is basic, it is easy to capture carbon dioxide, which is weakly acidic. On the other hand, if the powder pH exceeds 14, the paint will gel and it will be difficult to achieve high dispersibility. More preferably, the powder pH is 8.2 to 13.5.
本実施形態に係るナトリウムフェライト粒子粉末は、ＢＥＴ比表面積が１～７ｍ２／ｇであることが好ましい。ＢＥＴ比表面積が１ｍ２／ｇ未満であると、気体中に含まれる二酸化炭素と接触しにくくなり、二酸化炭素の吸収性能が低くなる。また、ＢＥＴ比表面積が７ｍ２／ｇを超えると工業的な生産が困難となる。より好ましくは、ＢＥＴ比表面積が１．３～６．５ｍ２／ｇである。さらにより好ましくは、１．５～６．０ｍ２／ｇである。 The sodium ferrite particles according to this embodiment preferably have a BET specific surface area of 1 to 7 m 2 /g. If the BET specific surface area is less than 1 m 2 /g, the particles are less likely to come into contact with carbon dioxide contained in the gas, resulting in a reduced carbon dioxide absorption performance. If the BET specific surface area exceeds 7 m 2 /g, industrial production becomes difficult. More preferably, the BET specific surface area is 1.3 to 6.5 m 2 /g. Even more preferably, the BET specific surface area is 1.5 to 6.0 m 2 /g.
本実施形態に係るナトリウムフェライト粒子粉末は、平均一次粒子径が５０～１０００ｎｍであることが好ましい。５０ｎｍ未満であれば工業的な生産が困難となる。また、１０００ｎｍを超えると二酸化炭素の吸収性能が低くなる。より好ましくは、１００～７００ｎｍである。 The sodium ferrite particles according to this embodiment preferably have an average primary particle diameter of 50 to 1000 nm. If it is less than 50 nm, industrial production becomes difficult. If it exceeds 1000 nm, the carbon dioxide absorption performance decreases. More preferably, it is 100 to 700 nm.
本実施形態に係るナトリウムフェライト粒子粉末は、一次粒子の軸比（平均長軸径／平均短軸径）が１．０～２．０であることが好ましい。該軸比が１を超える場合には、一次粒子同士が凝集しやすく、塗料化後、分散性が高い状態を維持することが困難となる。結果、成形性や加工性に優れた粒子粉末とは言い難いものとなる。また、軸比が１より小さいことはありえない。より好ましい軸比は１．０５～１．９の範囲であり、さらに好ましくは１．１～１．８の範囲である。 In the sodium ferrite particle powder according to this embodiment, the axial ratio (average major axis diameter/average minor axis diameter) of the primary particles is preferably 1.0 to 2.0. If the axial ratio exceeds 1, the primary particles tend to aggregate, making it difficult to maintain high dispersibility after coating. As a result, it is difficult to say that the particle powder has excellent moldability and processability. In addition, the axial ratio cannot be smaller than 1. A more preferable axial ratio is in the range of 1.05 to 1.9, and even more preferably in the range of 1.1 to 1.8.
本実施形態に係るナトリウムフェライト粒子粉末は、二酸化炭素の固定回収材として適応した場合、二酸化炭素を含む気体中から二酸化炭素を選択的に吸着でき、固定できる。前記吸着温度は、室温～排ガス出口温度の１０℃～１００℃程度である。さらに好ましくは、１０℃～５０℃程度である。外部からの追加加熱が必要ないことにより、吸着にかかるエネルギーコストが低く抑えられる（以上、二酸化炭素固定工程）。 When the sodium ferrite particle powder according to this embodiment is applied as a carbon dioxide fixation and capture material, it can selectively adsorb and fix carbon dioxide from a gas containing carbon dioxide. The adsorption temperature is about 10°C to 100°C, which is between room temperature and the exhaust gas outlet temperature. More preferably, it is about 10°C to 50°C. Since no additional heating from the outside is required, the energy cost required for adsorption can be kept low (above, carbon dioxide fixation process).
本実施形態に係るナトリウムフェライト粒子粉末は、前述の二酸化炭素の固定工程で取り込んだ二酸化炭素を、二酸化炭素を含まないガス雰囲気下で、５０℃超過１５０℃以下の温度で脱離し、二酸化炭素を回収することが好ましい。脱離温度が１５０℃以下と低いことにより、脱離にかかるエネルギーコストが低く抑えられる（以上、二酸化炭素回収工程）。 The sodium ferrite particle powder according to this embodiment preferably desorbs the carbon dioxide taken in during the carbon dioxide fixation process described above at a temperature above 50°C and below 150°C in a gas atmosphere not containing carbon dioxide, and recovers the carbon dioxide. By setting the desorption temperature at a low temperature of 150°C or less, the energy cost required for desorption can be kept low (above, carbon dioxide recovery process).
本実施形態に係るナトリウムフェライト粒子粉末は、二酸化炭素の固定回収材として二酸化炭素と接触させる場合、吸着塔の空塔速度を制御することができる。即ち、ナトリウムフェライト粒子粉末を造粒、または、担体担持させ、直径が１００μｍ～１０ｍｍ程度の球状成形体にしてもよい。より好ましくは、直径が２００μｍ～７ｍｍの球状成形体である。これは、前記成形体の直径が大きくなっても、二酸化炭素との接触を阻害しないように、ナトリウムフェライト粒子粉末を含む成形体は１～１０００ｍ２／ｇの比表面積を有することが好ましい。また、成形体の形状は、特に限定はないが、球状以外にも、紡錘状、直方体状、サイコロ状などが好ましい。また、ナトリウムフェライト粒子粉末を塗料化し、メッシュ、不織布、ハニカムなどに塗布し、二酸化炭素を固定回収できるようにしたもの、または、ナトリウムフェライト粒子粉末をカラムに充填し、二酸化炭素を固定回収できるようにフィルター化することもできる。 The sodium ferrite particles according to the present embodiment can control the superficial velocity of an adsorption tower when contacted with carbon dioxide as a carbon dioxide fixation and capture material. That is, the sodium ferrite particles may be granulated or supported on a carrier to form a spherical molded body having a diameter of about 100 μm to 10 mm. More preferably, the spherical molded body has a diameter of 200 μm to 7 mm. This is because the molded body containing the sodium ferrite particles preferably has a specific surface area of 1 to 1000 m 2 /g so that the contact with carbon dioxide is not hindered even if the diameter of the molded body increases. The shape of the molded body is not particularly limited, but spindle, rectangular, cube, and the like are preferable in addition to a spherical shape. The sodium ferrite particles may be made into a paint and applied to a mesh, nonwoven fabric, honeycomb, or the like to fix and capture carbon dioxide, or the sodium ferrite particles may be packed into a column to form a filter to fix and capture carbon dioxide.
次に、本発明の一実施形態に係るナトリウムフェライト粒子粉末の製造方法について述べる。 Next, we will describe a method for producing sodium ferrite particles according to one embodiment of the present invention.
本実施形態に係るナトリウムフェライト粒子粉末は、銅及び銀からなる１価金属群より選ばれた少なくとも１種類以上の金属化合物粒子粉末、酸化鉄粒子粉末及びナトリウム原料粒子粉末を混合して、１５０～４００℃の温度で水蒸気加熱による固相反応をすることで得ることができる。なお、このような方法で各原料を混合して固相反応させることにより、上記１価金属は、ナトリウムフェライト中で固溶、または、特定の結晶形態を持たない状態で存在することとなる。 The sodium ferrite particles according to this embodiment can be obtained by mixing at least one metal compound particle powder selected from the group of monovalent metals consisting of copper and silver, iron oxide particle powder, and sodium raw material particle powder, and carrying out a solid-phase reaction by heating with steam at a temperature of 150 to 400°C. By mixing the raw materials in this manner and carrying out a solid-phase reaction, the monovalent metal is present in the sodium ferrite in a state of solid solution or without a specific crystal form.
前述の金属化合物粒子粉末、酸化鉄粒子粉末及びナトリウム原料粒子粉末を固相反応させた場合、金属化合物粒子粉末に含まれる１価金属成分がナトリウムフェライトの一次粒子の成長を抑える傾向にあった。そのため、ＢＥＴ比表面積の大きい粒子粉末となり、二酸化炭素の固定回収材として好ましい。また、固相反応の特徴として、ナトリウムフェライトの結晶成長が等方向になりやすいため、一次粒子の軸比が抑えられる傾向であった。 When the aforementioned metal compound particle powder, iron oxide particle powder, and sodium raw material particle powder were subjected to a solid-state reaction, the monovalent metal components contained in the metal compound particle powder tended to suppress the growth of the primary particles of sodium ferrite. This resulted in a particle powder with a large BET specific surface area, which is preferable as a material for fixing and capturing carbon dioxide. In addition, as a characteristic of the solid-state reaction, the crystal growth of sodium ferrite tends to be isotropic, so the axial ratio of the primary particles tends to be suppressed.
銅及び銀からなる１価金属は酸化物換算として、酸化鉄に対して、０．０５～５重量％であることが好ましい。前述したように、二酸化炭素の固定回収性能を高める場合もあるからである。上記金属の含有量は、より好ましくは、０．１～５重量％である。 The monovalent metals consisting of copper and silver are preferably 0.05 to 5% by weight, calculated as oxide, relative to the iron oxide. As mentioned above, this may improve the carbon dioxide capture and recovery performance. The content of the above metals is more preferably 0.1 to 5% by weight.
酸化鉄粒子粉末としては、ヘマタイト、マグネタイト、マグヘマイト、ゲーサイトなどを用いることができる。α－ナトリウムフェライトの結晶相を多く含ませるために、酸素六方格子がα－ナトリウムフェライトの結晶相と同じ・・・ＡＢＣＡＢＣ・・・のパターンであるスピネル構造のマグネタイト及びマグヘマイトが好ましい。（参考文献 岡本祥一、「ナトリウムオルソフェライトの結晶生成と相転移」、長岡技術科学大学 研究報告第８号（１９８６）３７－４２頁） Hematite, magnetite, maghemite, goethite, etc. can be used as iron oxide particle powder. In order to contain a large amount of α-sodium ferrite crystal phase, magnetite and maghemite with a spinel structure in which the oxygen hexagonal lattice has the same ...ABCABC... pattern as the α-sodium ferrite crystal phase are preferred. (Reference: Shoichi Okamoto, "Crystal Formation and Phase Transition of Sodium Orthoferrite," Nagaoka University of Technology Research Report No. 8 (1986) pp. 37-42)
酸化鉄粒子粉末の形状としては、針状、紡錘状、粒状、球状、４面体、６面体、８面体などから選ぶことができる。 The shape of the iron oxide particles can be selected from needle, spindle, granular, spherical, tetrahedral, hexahedral, octahedral, etc.
酸化鉄粒子粉末の粒子径としては、１０ｎｍ～１μｍまでの任意のサイズのものを選ぶことができる。 The particle size of the iron oxide powder can be any size between 10 nm and 1 μm.
ナトリウム原料の粒子粉末としては、亜硝酸ナトリウム、硫酸ナトリウム、炭酸ナトリウム、炭酸水素ナトリウム、水酸化ナトリウム、酸化ナトリウムなどを用いることができる。ただし、工業的な利用を考えた場合、製造時に有毒な亜硝酸ガス、亜硫酸ガスなどを発生させる恐れのある亜硝酸ナトリウム、硫酸ナトリウムなどは避けるべきである。 Sodium raw material powders that can be used include sodium nitrite, sodium sulfate, sodium carbonate, sodium bicarbonate, sodium hydroxide, and sodium oxide. However, when considering industrial use, sodium nitrite and sodium sulfate should be avoided because they may generate toxic nitrous acid gas and sulfurous acid gas during production.
銅及び銀からなる１価金属群より選ばれた少なくとも１種類以上の金属化合物粒子粉末としては、各種金属の酸化物、水酸化物、塩化物、炭酸塩などを原料として用いればよい。また、前記金属の複合体を用いても良い。 As the powder of at least one metal compound selected from the group of monovalent metals consisting of copper and silver, various metal oxides, hydroxides, chlorides, carbonates, etc. may be used as raw materials. Composites of the above metals may also be used.
一般に固相反応は、固体と固体を混合し、溶媒を介さず元素を移動させて反応させる合成方法である。反応母液としての溶媒を用いないため、液相反応に用いた場合の溶媒などの廃棄物が抑えられる。また、本発明の特徴でもある低温での固相反応の場合、極めて高濃度反応となり得るため、エネルギーコストも低く抑えられる。また、前記高反応濃度や洗浄の必要性がないため、生成物の高収率が期待できる。 In general, solid-phase reactions are synthesis methods in which solids are mixed and reacted by transferring elements without the use of a solvent. Because no solvent is used as the reaction mother liquid, waste such as solvents that would be generated in a liquid-phase reaction is reduced. In addition, in the case of solid-phase reactions at low temperatures, which is a feature of the present invention, extremely high-concentration reactions can be achieved, so energy costs can also be kept low. Furthermore, because there is no need for the high reaction concentration or washing, a high yield of the product can be expected.
また、水蒸気を熱源とした固相反応では、酸化鉄とナトリウム源との接触界面に微量の水分が介在することにより、接触界面の酸塩基反応が促進され、未反応生成物であるマグネタイト相、または、マグへマイト相などが著しく少ない、純度の高いナトリウムフェライトとなり、好ましい。 In addition, in a solid-phase reaction using water vapor as a heat source, the presence of a small amount of moisture at the contact interface between the iron oxide and the sodium source promotes the acid-base reaction at the contact interface, resulting in a high-purity sodium ferrite with significantly less unreacted magnetite phase or maghemite phase, which is preferable.
また、水蒸気を熱源とした４００℃以下の固相反応では、酸化鉄とナトリウム源との接触界面の熱が均一に伝わるため、生成するナトリウムフェライトの結晶相が純度の高いα－ナトリウムフェライト相となり、好ましい。 In addition, in a solid-state reaction at 400°C or less using steam as a heat source, heat is transferred uniformly to the contact interface between the iron oxide and the sodium source, so the crystalline phase of the sodium ferrite produced is a highly pure α-sodium ferrite phase, which is preferable.
＜作用＞
本実施形態において、銅及び銀からなる１価金属群より選ばれた少なくとも１種類以上の金属が、固溶、または、特定の結晶形態を持たない状態で、酸化物換算として０．０５～５重量％存在するナトリウムフェライト粒子粉末には、更に気体中の二酸化炭素を吸着し、固体内に閉じ込め、加熱により、二酸化炭素を放出する優れた性質を持っている。これらは、純粋なナトリウムフェライトよりも、低い温度で固定化した二酸化炭素を回収することが可能となっている。詳細は明らかではないが、これは、それらの金属成分の存在により、二酸化炭素を取り込んだＮａ１－ｘＦｅＯ２と炭酸ナトリウムの混合相から、より低いエネルギー付与で二酸化炭素を揮発させる、または、より低いエネルギー付与でナトリウムフェライトに戻る触媒作用を起こしているものと考えられる。また、本発明に係る粒子粉末では、Ｎａ／Ｆｅのモル比が０．７５～１．２５であるため、ナトリウムフェライト結晶相を多く含むことができて、二酸化炭素の固定回収性能が良好となり、Ｎａの割合が過剰に多くないため、粒子粉末を塗料化した際の塗料のゲル化の原因となる副生成物のＮａＯＨやＮａ２ＣＯ３等のアルカリ成分も残存しにくくなるため、高分散性の塗料となり得る。これらの特性が相まって、本発明に係るナトリウムフェライト粒子粉末によると、二酸化炭素を室温から１００℃までの温度範囲で固定化し、１５０℃以下で固定化した二酸化炭素を回収できる。
<Action>
In this embodiment, the sodium ferrite particles, which contain at least one metal selected from the group of monovalent metals consisting of copper and silver, in a state of solid solution or not having a specific crystal form, and are present in an amount of 0.05 to 5% by weight calculated as oxide, further have the excellent property of adsorbing carbon dioxide in gas, trapping it in a solid, and releasing the carbon dioxide when heated. These make it possible to recover the immobilized carbon dioxide at a lower temperature than pure sodium ferrite. Although the details are not clear, it is believed that the presence of these metal components causes a catalytic action to volatilize carbon dioxide from the mixed phase of Na 1-x FeO 2 and sodium carbonate that has taken in carbon dioxide with less energy applied, or to return to sodium ferrite with less energy applied. Furthermore, since the particle powder according to the present invention has a molar ratio of Na/Fe of 0.75 to 1.25, it can contain a large amount of sodium ferrite crystal phase, resulting in good carbon dioxide fixation and recovery performance, and since the proportion of Na is not excessively high, alkaline components such as NaOH and Na2CO3 , which are by-products that cause gelation of paint when the particle powder is made into paint, are less likely to remain, making it possible to produce a highly dispersible paint. Due to the combination of these properties, the sodium ferrite particle powder according to the present invention can fix carbon dioxide in a temperature range from room temperature to 100°C and recover the fixed carbon dioxide at 150°C or less.
本発明の代表的な実施の形態は、次の通りである。 A typical embodiment of the present invention is as follows:
本発明に係るナトリウムフェライト粒子粉末、及びそれらの原料中の元素分析（但し、酸素は除く）は、リガク製走査型蛍光Ｘ線分析装置ＺＳＸ ＰｒｉｍｕｓＩＩで行った。 Elemental analysis (excluding oxygen) of the sodium ferrite particles according to the present invention and their raw materials was performed using a Rigaku ZSX Primus II scanning X-ray fluorescence analyzer.
本発明に係るナトリウムフェライト粒子粉末の結晶相の重量％は、ＢＲＵＫＥＲ製全自動多目的Ｘ線回折装置Ｄ８ ＡＤＶＡＮＣＥによって同定し、定量した。 The weight percentage of the crystalline phase of the sodium ferrite particles according to the present invention was identified and quantified using a BRUKER D8 ADVANCE fully automated multipurpose X-ray diffractometer.
本発明に係るナトリウムフェライト粒子粉末のＢＥＴ比表面積は、ＱＵＡＮＴＡ ＣＨＲＯＭＥ製マルチソーブ－１６を用い、窒素を用いたＢＥＴ法により測定した。 The BET specific surface area of the sodium ferrite particles according to the present invention was measured by the BET method using nitrogen and a Multisorb-16 made by QUANTA CHROME.
本発明に係るナトリウムフェライト粒子粉末の一次粒子の平均長軸径及び平均短軸径は、日立ハイテク製走査型電子顕微鏡Ｓ－４８００による顕微鏡写真に示される一次粒子３５０個の粒子径の長軸径と短軸径をそれぞれ測定し、その平均値で示した。 The average major axis diameter and the average minor axis diameter of the primary particles of the sodium ferrite particle powder according to the present invention were calculated by measuring the major axis diameter and the minor axis diameter of 350 primary particles shown in a micrograph taken with a Hitachi High-Technologies S-4800 scanning electron microscope, and expressing the average value.
本発明に係るナトリウムフェライト粒子粉末の軸比は前記平均長軸径の平均短軸径に対する比（平均長軸径／平均短軸径）として示した。 The axial ratio of the sodium ferrite particles according to the present invention is shown as the ratio of the average major axis diameter to the average minor axis diameter (average major axis diameter/average minor axis diameter).
本発明に係るナトリウムフェライト粒子粉末の平均一次粒子径は、平均長軸径と平均短軸径の平均値として示した。 The average primary particle size of the sodium ferrite particles according to the present invention is shown as the average value of the average major axis diameter and the average minor axis diameter.
本発明に係るナトリウムフェライト粒子粉末の粉体ｐＨ値は、試料５ｇを３００ｍｌの三角フラスコに秤取り、煮沸した純水１００ｍｌを加え、加熱して煮沸状態を約５分間保持した後、栓をして常温まで放冷し、減量に相当する水を加えて再び栓をして１分間振り混ぜ、５分間静置した後、得られた上澄み液のｐＨをＪＩＳ Ｚ８８０２－７に従って測定し、得られた値を粉体ｐＨ値とした。 The powder pH value of the sodium ferrite particle powder according to the present invention was measured by weighing 5 g of sample into a 300 ml Erlenmeyer flask, adding 100 ml of boiled pure water, heating and maintaining the boiling state for about 5 minutes, then plugging and allowing to cool to room temperature, adding water equivalent to the weight lost, plugging again, shaking for 1 minute, leaving to stand for 5 minutes, and measuring the pH of the resulting supernatant liquid according to JIS Z8802-7, and the value obtained was taken as the powder pH value.
本発明に係るナトリウムフェライト粒子粉末の二酸化炭素の固定回収能力は、試料１００ｍｇを燃焼ボートに乗せて、入口出口配管を付けたアクリルパイプに入れ、入口から、湿度２０～１００％の範囲内、二酸化炭素濃度１～１００ｖｏｌ％の範囲内に調整した（二酸化炭素＋窒素）混合気体を５００ｍＬ／ｍｉｎで導入して、２時間後の二酸化炭素の吸着量を日立ハイテク製示差熱熱重量同時測定装置ＳＴＡ７０００にて、室温から２００℃まで昇温し、その熱減量から、二酸化炭素の固定回収量を求めた。 The carbon dioxide fixation and recovery capacity of the sodium ferrite particle powder according to the present invention was evaluated by placing 100 mg of a sample on a combustion boat, placing it in an acrylic pipe with inlet and outlet piping, and introducing a (carbon dioxide + nitrogen) mixed gas adjusted to a humidity range of 20 to 100% and a carbon dioxide concentration range of 1 to 100 vol% from the inlet at 500 mL/min. The amount of carbon dioxide adsorbed after 2 hours was measured by heating the sample from room temperature to 200°C using a Hitachi High-Tech simultaneous differential thermal and thermogravimetric analyzer STA7000, and calculating the amount of carbon dioxide fixation and recovery from the heat loss.
本発明に係るナトリウムフェライト粒子粉末の分散性評価として、ナトリウムフェライト粉末を１０重量部秤量し、アルキルアミン１重量部、プロピレングリコールモノメチルエーテルアセテート８９重量部、１．５ｍｍガラスビーズ１００重量部を加えた。その後、前記混合物をペイントコンディショナーで２時間振とうし、スラリーからガラスビーズをろ別して取り除いた。得られたスラリーを大塚電子製濃厚系粒径アナライザーＦＰＡＲ１０００により、分散粒子径を測定した。散乱強度分布の累積５０％値（Ｄ５０）が平均一次粒子径の２倍以下の場合、分散性良好の試料と判断し「〇」とし、２倍を超える場合、「×」とした。 To evaluate the dispersibility of the sodium ferrite particle powder according to the present invention, 10 parts by weight of sodium ferrite powder was weighed, and 1 part by weight of alkylamine, 89 parts by weight of propylene glycol monomethyl ether acetate, and 100 parts by weight of 1.5 mm glass beads were added. The mixture was then shaken for 2 hours in a paint conditioner, and the glass beads were filtered out and removed from the slurry. The dispersed particle size of the obtained slurry was measured using a concentrated particle size analyzer FPAR1000 manufactured by Otsuka Electronics. When the cumulative 50% value (D50) of the scattering intensity distribution was less than twice the average primary particle size, the sample was judged to have good dispersibility and was marked with "◯", and when it exceeded twice, it was marked with "X".
＜ナトリウムフェライト粒子粉末の製造方法＞
実施例１
酸化鉄微粒子１（戸田工業製１００ＥＤ、ヘマタイト、比表面積１１ｍ２／ｇ）を１０重量部とし、それに対しナトリウム原料の水酸化ナトリウム粒子粉末をＮａ／Ｆｅ＝１．０（モル比）となるように秤量し、酸化銀（Ｉ）を０．７重量部秤量し、添加した。各原料混合後、サンプルミルにて混合粉砕した。この混合粉砕物をるつぼに入れ、２５０℃にて１６時間水蒸気固相反応させた。その後、室温まで冷却し、サンプルミルにて粉砕することにより、ナトリウムフェライト粒子粉末を得た。得られた粒子粉末のＢＥＴ比表面積は２．０ｍ２／ｇであった。走査型電子顕微鏡による一次粒子の定量化により、平均長軸径は０．６μｍ、平均短軸径は０．４μｍ、平均一次粒子径は０．５μｍであり、軸比は１．５であった。粉体ｐＨは１３．４と比較的高かった。
<Method of producing sodium ferrite particles>
Example 1
The iron oxide fine particles 1 (Toda Kogyo 100ED, hematite, specific surface area 11 m 2 /g) were used as 10 parts by weight, and the sodium hydroxide particle powder as the sodium raw material was weighed out so that Na/Fe = 1.0 (molar ratio), and 0.7 parts by weight of silver oxide (I) was weighed and added. After mixing the raw materials, they were mixed and ground in a sample mill. The mixed and ground product was placed in a crucible and subjected to a water vapor solid-phase reaction at 250°C for 16 hours. Thereafter, the mixture was cooled to room temperature and ground in a sample mill to obtain sodium ferrite particle powder. The BET specific surface area of the obtained particle powder was 2.0 m 2 /g. Quantification of the primary particles using a scanning electron microscope revealed that the average major axis diameter was 0.6 μm, the average minor axis diameter was 0.4 μm, the average primary particle diameter was 0.5 μm, and the axial ratio was 1.5. The powder pH was relatively high at 13.4.
得られたナトリウムフェライト粒子粉末に含まれる元素分析を蛍光Ｘ線で行ったところ、Ｎａ／Ｆｅのモル比は１．０で原料の仕込み比とほぼ同等であり、また、銀分がＡｇ２Ｏ換算として４．８重量％含まれていた。更に、得られた粉末は、粉末Ｘ線回折パターンの定量化により、９９重量％以上のα－ナトリウムフェライト結晶相であることが分かった。従って、銀分はＡｇ２Ｏとしてアモルファス状か、Ａｇとして各結晶相に固溶していると推定される。 Elemental analysis of the obtained sodium ferrite particles by X-ray fluorescence revealed that the molar ratio of Na/Fe was 1.0, which was almost the same as the raw material charge ratio, and that the silver content was 4.8% by weight calculated as Ag 2 O. Furthermore, quantification of the powder X-ray diffraction pattern revealed that the obtained powder was 99% by weight or more of an α-sodium ferrite crystal phase. Therefore, it is estimated that the silver content is either amorphous as Ag 2 O or solid-dissolved in each crystal phase as Ag.
得られたナトリウムフェライト粒子粉末の二酸化炭素の固定回収性能を調べるために、試料１．００重量部をＮｏ.２燃焼ボート（１２×６０×９ｍｍ）に乗せ、モデル燃焼排ガス５００ｍＬ／ｍｉｎに３時間通気した。一般に、大気中で燃料を燃やしたときの排ガスは最大、窒素８０ｖｏｌ％、二酸化炭素２０ｖｏｌ％、湿度８０～１００％で構成される。そのため、室温２５℃にて、窒素４００ｍＬ／ｍｉｎと二酸化炭素１００ｍＬ／ｍｉｎを混合し、これを水中にバブリングして、二酸化炭素２０ｖｏｌ％、相対湿度ＲＨ８０％のモデル燃焼排ガスとした。 To examine the carbon dioxide fixation and recovery performance of the obtained sodium ferrite particle powder, 1.00 parts by weight of the sample was placed on No. 2 combustion boat (12 x 60 x 9 mm) and aerated with model combustion exhaust gas at 500 mL/min for 3 hours. In general, the exhaust gas produced when fuel is burned in the atmosphere is composed of a maximum of 80 vol% nitrogen, 20 vol% carbon dioxide, and 80-100% humidity. Therefore, at room temperature of 25°C, 400 mL/min of nitrogen and 100 mL/min of carbon dioxide were mixed and bubbled into water to produce a model combustion exhaust gas with 20 vol% carbon dioxide and a relative humidity of 80% RH.
通気後の試料を１０ｍｇ秤量し、熱重量測定装置により、乾燥空気３００ｍＬ／ｍｉｎで通気しながら、２００℃まで１０℃／ｍｉｎで昇温して、試料に吸着された二酸化炭素の脱離温度と脱離量を測定した。横軸を試料温度とした測定チャートを図１に示す。ＴＧ曲線は初期を１００重量％としたときの各温度における残存試料の重量％であり、試料の減少量を二酸化炭素の放出によるものとみなした。ＤＴＧ曲線はＴＧ曲線の微分曲線であり、ＤＴＧ曲線の極大値を取る温度を二酸化炭素の脱離温度とみなした。ＤＴＡ曲線は下に凸となる曲線を示し、吸熱反応が９９℃付近で行われていることが分かった。これをＮａＨＣＯ３の熱分解反応とみなして定量化したところ、二酸化炭素の脱離温度は９３℃で、二酸化炭素の脱離量は試料固形分に対し８重量％であり、優れた二酸化炭素の固定回収性能があることが明らかとなった。 The sample after aeration was weighed out in an amount of 10 mg, and the sample was heated to 200°C at 10°C/min while being aerated with 300 mL/min of dry air using a thermogravimetric measuring device, and the desorption temperature and amount of carbon dioxide adsorbed on the sample were measured. A measurement chart with the sample temperature on the horizontal axis is shown in Figure 1. The TG curve is the weight percent of the remaining sample at each temperature when the initial value is taken as 100% by weight, and the amount of the sample reduced was considered to be due to the release of carbon dioxide. The DTG curve is a differential curve of the TG curve, and the temperature at which the DTG curve has a maximum value was considered to be the desorption temperature of carbon dioxide. The DTA curve shows a curve that is convex downward, and it was found that the endothermic reaction was taking place around 99°C. When this was quantified as a thermal decomposition reaction of NaHCO3 , the desorption temperature of carbon dioxide was 93°C, and the amount of carbon dioxide desorption was 8% by weight relative to the solid content of the sample, revealing that there was excellent carbon dioxide fixation and recovery performance.
さらに、通気後の試料を再調製し、重量を測定したところ、１．２０重量部であり、２０重量％の質量の増量が確認された。この試料のＸ線回折を測定したところ、８０重量％のＮａ１－ｘＦｅＯ２と２０重量％のＮａＨＣＯ３が確認され、ナトリウムフェライト粒子粉末に二酸化炭素が固定化されていることが分かった。さらに、この試料を電気炉にて、１００℃で１時間加熱し、重量を測定したところ、１．１２重量部であり、このサイクルで０．０８重量部（ＮａＦｅＯ２固形分に対して８重量％）の二酸化炭素を吸脱着できることが分かった。この試料のＸ線回折を測定したところ、８８重量％のＮａＦｅＯ２と１２重量％のＮａ２ＣＯ３が確認された。さらに、この試料に前述と同様に、二酸化炭素を接触させると、１．２０重量部に増量し、加熱すると１．１２重量部に減量して０．０８重量部の二酸化炭素を吸脱着できた。この操作を１０回繰り返し、質量の増量と減量に変化がないことを確認した。このことより、ナトリウムフェライト粒子粉末は、優れた二酸化炭素の固定回収性能、特に、繰り返し性に優れていることが明らかとなった。 Furthermore, the sample after aeration was re-prepared and the weight was measured, and it was 1.20 parts by weight, and an increase in mass of 20% by weight was confirmed. When the X-ray diffraction of this sample was measured, 80% by weight of Na 1-x FeO 2 and 20% by weight of NaHCO 3 were confirmed, and it was found that carbon dioxide was fixed in the sodium ferrite particle powder. Furthermore, when this sample was heated at 100 ° C. for 1 hour in an electric furnace and the weight was measured, it was 1.12 parts by weight, and it was found that 0.08 parts by weight (8% by weight relative to the NaFeO 2 solid content) of carbon dioxide could be adsorbed and desorbed in this cycle. When the X-ray diffraction of this sample was measured, it was confirmed that 88% by weight of NaFeO 2 and 12% by weight of Na 2 CO 3 were confirmed. Furthermore, when this sample was contacted with carbon dioxide in the same manner as described above, the weight increased to 1.20 parts by weight, and when heated, the weight decreased to 1.12 parts by weight, and 0.08 parts by weight of carbon dioxide could be adsorbed and desorbed. This operation was repeated 10 times, and it was confirmed that there was no change in the increase or decrease in mass. This demonstrates that the sodium ferrite particles have excellent carbon dioxide fixation and recovery performance, particularly excellent repeatability.
得られたナトリウムフェライト粒子粉末の分散性を評価したところ、分散粒子径が平均一次粒子径の２倍以内であり、良好であった。 The dispersibility of the resulting sodium ferrite particle powder was evaluated and found to be good, with the dispersed particle size being within two times the average primary particle size.
実施例２～６
酸化鉄微粒子、ナトリウム源及び金属酸化物の種類と量を種々変化させた以外は前記実施例１と同様にして、本発明に係るナトリウムフェライト粒子粉末を得た。
Examples 2 to 6
Sodium ferrite particles according to the present invention were obtained in the same manner as in Example 1, except that the types and amounts of the iron oxide fine particles, the sodium source, and the metal oxide were variously changed.
これらの実施例における製造条件を表１に、得られたナトリウムフェライト粒子粉末の諸特性を表２に、その二酸化炭素の固定回収性能及び分散性を表３に示す。二酸化炭素の回収性能の評価は、二酸化炭素濃度４０００ｐｐｍのデシケータ（１３Ｌ）中に二酸化炭素吸収材を１０ｇ入れ、３０分後の二酸化炭素濃度が２５００ｐｐｍ以下であるものを○、２５００ｐｐｍを超えるものを×とした。分散性良好の試料は○、そうでない場合は×を表３に記した。 The manufacturing conditions in these examples are shown in Table 1, the properties of the obtained sodium ferrite particle powder in Table 2, and its carbon dioxide fixation and recovery performance and dispersibility in Table 3. The carbon dioxide recovery performance was evaluated by placing 10 g of the carbon dioxide absorbent in a desiccator (13 L) with a carbon dioxide concentration of 4000 ppm, and grading the carbon dioxide concentration after 30 minutes as ◯ if it was 2500 ppm or less, and ◯ if it was over 2500 ppm. Samples with good dispersibility are marked ◯ in Table 3, and samples with poor dispersibility are marked ◯ if it was not.
比較例１
酸化鉄１を１０重量部とし、それに対して水酸化ナトリウム粒子粉末をＦｅ：Ｎａ＝１：１（モル比）となるように秤量し、純水１００重量部を加えて水酸化ナトリウム粒子粉末を溶解させ、自動乳鉢により、２時間混練した。これを、８０℃で２時間乾燥し、サンプルミルにて混合粉砕した。この混合粉砕物をるつぼに入れ、４００℃にて１６時間熱処理した。生成物は、粉末Ｘ線回折により、２５重量％がα－ナトリウムフェライト結晶相で、残り７５重量％がγ－Ｆｅ２Ｏ３結晶相であることが分かった。ＢＥＴ比表面積は１．０ｍ２／ｇであった。軸比は３．８であった。また、実施例と同様にして二酸化炭素の固定回収性能を調べたところ、２００℃まで昇温したが二酸化炭素の脱離は確認できなかった。
Comparative Example 1
The iron oxide 1 was used as 10 parts by weight, and the sodium hydroxide particles were weighed out so that the ratio of Fe:Na was 1:1 (molar ratio). 100 parts by weight of pure water was added to dissolve the sodium hydroxide particles, and the mixture was kneaded for 2 hours in an automatic mortar. The mixture was dried at 80°C for 2 hours, and mixed and ground in a sample mill. The mixed and ground product was placed in a crucible and heat-treated at 400°C for 16 hours. The product was found by powder X-ray diffraction to be 25% by weight of α-sodium ferrite crystal phase and the remaining 75% by weight of γ-Fe 2 O 3 crystal phase. The BET specific surface area was 1.0 m 2 /g. The axial ratio was 3.8. In addition, when the carbon dioxide fixation and recovery performance was examined in the same manner as in the examples, the temperature was raised to 200°C, but desorption of carbon dioxide was not confirmed.
この比較例の製造条件を表１に、得られたナトリウムフェライト粒子粉末の諸特性を表２に、その二酸化炭素の固定回収性能及び分散性を表３に示す。 The manufacturing conditions for this comparative example are shown in Table 1, the properties of the resulting sodium ferrite particle powder are shown in Table 2, and its carbon dioxide fixation and recovery performance and dispersibility are shown in Table 3.
以上のように、本発明に係るナトリウムフェライト粒子粉末は、二酸化炭素の吸着、脱離に優れた二酸化炭素の固定回収材であることが明らかである。また、前記粒子粉末は分散性に優れるため、成形性や加工性に富んだ粒子粉末であることも明らかである。 As described above, it is clear that the sodium ferrite particle powder according to the present invention is a carbon dioxide fixation and recovery material that is excellent in adsorption and desorption of carbon dioxide. In addition, it is also clear that the particle powder has excellent dispersibility, and therefore is a particle powder with excellent moldability and processability.
本発明に係るナトリウムフェライト粒子粉末は、地球温暖化対策の一環として、温室効果ガス、特に、二酸化炭素の固定回収を行う材料であり、アミン水溶液などの危険物を用いることなく、非危険物の無機材料で二酸化炭素の吸脱着による固定回収を行える材料として好適である。 The sodium ferrite particles according to the present invention are a material that fixes and recovers greenhouse gases, particularly carbon dioxide, as part of measures against global warming, and are suitable as a material that can fix and recover carbon dioxide by adsorption and desorption using non-hazardous inorganic materials, without using hazardous materials such as aqueous amine solutions.
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