JP3693626B2 - Adsorbent - Google Patents
Adsorbent Download PDFInfo
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- JP3693626B2 JP3693626B2 JP2002117726A JP2002117726A JP3693626B2 JP 3693626 B2 JP3693626 B2 JP 3693626B2 JP 2002117726 A JP2002117726 A JP 2002117726A JP 2002117726 A JP2002117726 A JP 2002117726A JP 3693626 B2 JP3693626 B2 JP 3693626B2
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- gas
- nitrogen
- adsorbent
- zsm
- adsorption
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- 239000003463 adsorbent Substances 0.000 title claims description 46
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 123
- 239000007789 gas Substances 0.000 claims description 84
- 229910052757 nitrogen Inorganic materials 0.000 claims description 59
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 31
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 31
- 239000012535 impurity Substances 0.000 claims description 30
- 238000005342 ion exchange Methods 0.000 claims description 30
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical group [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 claims description 25
- 229910001431 copper ion Inorganic materials 0.000 claims description 25
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 21
- 239000010457 zeolite Substances 0.000 claims description 21
- 229910021536 Zeolite Inorganic materials 0.000 claims description 19
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 19
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 18
- 239000001301 oxygen Substances 0.000 claims description 18
- 229910052760 oxygen Inorganic materials 0.000 claims description 18
- 239000001257 hydrogen Substances 0.000 claims description 17
- 229910052739 hydrogen Inorganic materials 0.000 claims description 17
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 16
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 14
- 239000010949 copper Substances 0.000 claims description 12
- 239000001569 carbon dioxide Substances 0.000 claims description 11
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 11
- 150000002431 hydrogen Chemical class 0.000 claims description 11
- 229930195733 hydrocarbon Natural products 0.000 claims description 8
- 150000002430 hydrocarbons Chemical class 0.000 claims description 8
- 229910021529 ammonia Inorganic materials 0.000 claims description 7
- QKCGXXHCELUCKW-UHFFFAOYSA-N n-[4-[4-(dinaphthalen-2-ylamino)phenyl]phenyl]-n-naphthalen-2-ylnaphthalen-2-amine Chemical compound C1=CC=CC2=CC(N(C=3C=CC(=CC=3)C=3C=CC(=CC=3)N(C=3C=C4C=CC=CC4=CC=3)C=3C=C4C=CC=CC4=CC=3)C3=CC4=CC=CC=C4C=C3)=CC=C21 QKCGXXHCELUCKW-UHFFFAOYSA-N 0.000 claims description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 5
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 239000004215 Carbon black (E152) Substances 0.000 claims description 4
- 229910018503 SF6 Inorganic materials 0.000 claims description 4
- SFZCNBIFKDRMGX-UHFFFAOYSA-N sulfur hexafluoride Chemical compound FS(F)(F)(F)(F)F SFZCNBIFKDRMGX-UHFFFAOYSA-N 0.000 claims description 4
- 229960000909 sulfur hexafluoride Drugs 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- 238000001354 calcination Methods 0.000 claims 1
- 238000001179 sorption measurement Methods 0.000 description 67
- 229960005419 nitrogen Drugs 0.000 description 59
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 22
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 18
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 17
- 238000002474 experimental method Methods 0.000 description 16
- 230000008929 regeneration Effects 0.000 description 13
- 238000011069 regeneration method Methods 0.000 description 13
- 238000000034 method Methods 0.000 description 12
- 239000000377 silicon dioxide Substances 0.000 description 11
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 10
- 229910052743 krypton Inorganic materials 0.000 description 10
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 description 10
- 238000000746 purification Methods 0.000 description 10
- 229910052786 argon Inorganic materials 0.000 description 9
- 239000003795 chemical substances by application Substances 0.000 description 8
- 238000010304 firing Methods 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 229960001730 nitrous oxide Drugs 0.000 description 5
- 239000011261 inert gas Substances 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 4
- 235000013842 nitrous oxide Nutrition 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 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 description 2
- UBAZGMLMVVQSCD-UHFFFAOYSA-N carbon dioxide;molecular oxygen Chemical compound O=O.O=C=O UBAZGMLMVVQSCD-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004993 emission spectroscopy Methods 0.000 description 2
- 229910052736 halogen Inorganic materials 0.000 description 2
- 150000002367 halogens Chemical group 0.000 description 2
- 239000001307 helium Substances 0.000 description 2
- 229910052734 helium Inorganic materials 0.000 description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910001868 water Inorganic materials 0.000 description 2
- 229910052724 xenon Inorganic materials 0.000 description 2
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 2
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 1
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910001423 beryllium ion Inorganic materials 0.000 description 1
- 229940105305 carbon monoxide Drugs 0.000 description 1
- 229910002090 carbon oxide Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- OPQARKPSCNTWTJ-UHFFFAOYSA-L copper(ii) acetate Chemical compound [Cu+2].CC([O-])=O.CC([O-])=O OPQARKPSCNTWTJ-UHFFFAOYSA-L 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- -1 for example Substances 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052754 neon Inorganic materials 0.000 description 1
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 description 1
- 229960003753 nitric oxide Drugs 0.000 description 1
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 1
- 239000001272 nitrous oxide Substances 0.000 description 1
- 229910052756 noble gas Inorganic materials 0.000 description 1
- 150000002835 noble gases Chemical class 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000002594 sorbent Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- TXEYQDLBPFQVAA-UHFFFAOYSA-N tetrafluoromethane Chemical compound FC(F)(F)F TXEYQDLBPFQVAA-UHFFFAOYSA-N 0.000 description 1
- 238000001926 trapping method Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02C20/00—Capture or disposal of greenhouse gases
- Y02C20/10—Capture or disposal of greenhouse gases of nitrous oxide (N2O)
Landscapes
- Separation Of Gases By Adsorption (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、吸着剤に関し、詳しくは、精製対象ガスである高純度ガス中に含まれるアンモニア、三フッ化窒素、二酸化炭素、水素、酸素等の微量不純物を選択的吸着剤により吸着除去して超高純度のガスを得るための吸着剤に関する。
【０００２】
【従来の技術】
ヘリウム、アルゴン、クリプトン、キセノンあるいは窒素等の不活性ガス、その他各種のガスが、エレクトロニクス産業において広く使用されている。このようなエレクトロニクス分野で使用される不活性ガス等は、半導体の製造プロセス自体で使用するものと、あらゆる工程でパージあるいは希釈用のガスとして使用する一般用途のものとがあり、それぞれで必要とされる純度のレベルは大きく異なるが、少なくとも９９．９９９％以上は必要とされる。
【０００３】
特に、半導体製造プロセスで使用されるガスは、純度に対する要求が厳しく、各不純物量ともｐｐｂレベルであることが要求されている。半導体製造プロセスで使用されるガス中の不純物として除去すべきとされるガスは、酸素、二酸化炭素、水、一酸化炭素、水素あるいは炭化水素類等である。また、希ガス類にあっては、先に挙げた不純物に加えて窒素も除去対象となる。
【０００４】
一方、ガス吸着分離の分野において、Ｃａ−Ａ型、Ｎａ−Ｘ、Ｃａ−Ｘ型等のゼオライトは、一般に窒素及び一酸化炭素を比較的よく吸着することが知られており、実用に供されている。しかし、これらのゼオライトの吸着等温線は、低圧領域においては略直線であり、極めて低い濃度の窒素や一酸化炭素に対する吸着量が小さいため、ｐｐｍレベルでの精製に供することは事実上不可能だった。
【０００５】
また、特開昭６０−１５６５４８号公報には、シリカ対アルミナ比が１９以下で、かつ、銅イオンを含むＺＳＭ−５型ゼオライトを使用し、比較的高い濃度の一酸化炭素を含むガスから一酸化炭素を回収する方法が開示されている。この方法は、比較的高濃度に一酸化炭素を含むガスから一酸化炭素を分離回収する際に、一酸化炭素のみに選択性を示し、かつ、吸着容量の大きい吸着剤に関するものであって、捕捉方法に関する詳しい説明が無く、基本的に、ガス中に微量不純物として存在する一酸化炭素を除去する可能性を示唆するものではない。
【０００６】
さらに、特開昭６１−１８４３１号公報には、シリカ対アルミナ比が１０以下のＹ型、Ａ型又はＸ型ゼオライトに１価の銅又は銀あるいはその両方を担持させた吸着剤により、窒素と比較的高濃度の一酸化炭素とを含む混合ガスから一酸化炭素を吸着分離する技術が開示されている。前記公報記載の実施例に示された原料ガス中の一酸化炭素は、比較的高い濃度範囲であって、ｐｐｍレベルでの除去については触れられていないし、ＺＳＭ−５を基本吸着剤とすることについては何の示唆もない。
【０００７】
また、特開平３−６５２４２号公報には、銅−ゼオライト触媒の製法として、シリカ対アルミナ比が５〜１０００のゼオライトに銅をイオン交換により担持させて乾燥した後、該ゼオライトを容積比で０．０５〜０．５％の水素を添加した不活性ガス気流中で熱処理することが開示されている。ここで使用するゼオライトは、ＺＳＭ−５ゼオライトが最も好ましいとされているが、浄化結果として示されているものは、モデルガス中の一酸化炭素濃度が０．１１容積％に対して浄化率は５０〜７５％であって、ｐｐｍレベルの精製ではなく、しかも、窒素等の除去には触れていない。
【０００８】
【発明が解決しようとする課題】
このように、従来の吸着技術では、ガス中に微量に含まれる一酸化炭素、窒素、一酸化二窒素、一酸化窒素、二酸化窒素、アンモニア、三フッ化窒素、二酸化炭素、メタン、水素、酸素等の不純物を同時に除去することが困難であり、特に、不純物の除去のレベルをｐｐｍレベルの極微量とすることができないという問題があった。そこで本発明は、各種ガス中に含まれるアンモニア、三フッ化窒素、二酸化炭素、水素、酸素等の微量不純物を選択的にｐｐｍレベル以下まで吸着除去して超高純度のガスを得ることができる吸着剤を提供することを目的としている。
【０００９】
【課題を解決するための手段】
上記目的を達成するため、本発明の吸着剤は、アンモニア、三フッ化窒素、二酸化炭素、水素及び酸素の少なくとも１種を微量不純物として含む精製対象ガス中の前記微量不純物を吸着除去するための吸着剤であって、銅イオン交換したＺＳＭ−５型ゼオライトからなることを特徴とし、また、前記微量不純物に加えて、一酸化炭素、窒素、メタンの少なくとも１種を吸着除去することを特徴としている。
【００１０】
まず、本発明の微量不純物除去対象となるガス（精製対象ガス）は、例えば、前述のようなエレクトロニクス分野で使用される不活性ガスをはじめとする各種のガスであって、代表的なものとして、各種の希ガス、水素、酸素、二酸化炭素、炭化水素、水素の一部又は全部をハロゲン置換した炭化水素、六フッ化硫黄等を挙げることができる。また、本発明では、精製後のこれらガスの純度を９９．９９９９容量％以上、すなわち、精製後に不純物として含まれる成分の合計を１ｐｐｍ以下にすることを目標としている。
【００１１】
前記吸着剤は、ＺＳＭ−５型ゼオライト（以下、ＺＳＭ−５と記載するときがある）のナトリウムイオン等を銅イオン交換したゼオライトである。なお、以下の説明において、この銅イオン交換したゼオライトを、「Ｃｕ−ＺＳＭ−５」と記載することがある。銅イオン交換する前の原料となるＺＳＭ−５型ゼオライトは、市販の材料を使用することができるが、シリカ対アルミナ比が５〜５０であることが望ましい。ＺＳＭ−５におけるシリカ対アルミナ比が５０を超えると銅イオン交換量が少なくなり、微量不純物の吸着量が減少してしまう。また、シリカ対アルミナ比が５未満のＺＳＭ−５は、入手困難である。
【００１２】
Ｃｕ−ＺＳＭ−５における銅イオン交換率は、それぞれのゼオライトのイオン交換可能な量の少なくとも４０％以上であるあることが好ましい。これは、イオン交換された銅イオンが窒素及び一酸化炭素等の特異的吸着の要因となるからであり、銅イオン交換率が少なすぎると特異的吸着性能が発現しなくなってしまう。
【００１３】
ＺＳＭ−５中に含まれるナトリウムを銅にイオン交換する方法は、特に限定されるものではなく、従来から行われている周知の方法を採用することができる。例えば、銅の可溶性塩（硝酸塩、酢酸塩、シュウ酸塩、塩酸塩等）の水溶液にＺＳＭ−５を浸漬することによってナトリウムを銅にイオン交換することができる。この場合、銅塩の濃度、浸漬時間、浸漬温度、浸漬回数等を選択することによって銅イオン交換量を所望の量に調節することができる。
【００１４】
イオン交換した後は、水を用いて洗浄し、乾燥後に適当な温度で焼成することによって使用可能な状態となる。このときの乾燥温度は１００℃程度が適当であり、焼成温度は、窒素ガス雰囲気下で３５０℃以上、特に、５００〜８００℃が適当である。この吸着剤の特異的吸着性能は、１価の銅イオンの存在によって発現すると考えられるので、５００℃未満の焼成温度では２価から１価への変化が不十分で、十分な吸着性能を発現させることが困難であり、逆に８００℃以上の温度では、ゼオライトの構造自体が破壊される可能性がある。
【００１５】
銅イオン交換したゼオライト中に含まれる銅イオンの量は、任意の方法で測定できるが、例えば、ＩＣＰ発光分析法（誘導電荷発光分析法）により測定することができる。なお、本発明におけるイオン交換率は、１個の銅イオンが２個のナトリウムイオンと交換するという仮定から求めている。すなわち、イオン交換時点では、銅イオンは２価として存在すると仮定している。実際には、１価の銅イオンも存在するため、計算値として１００％以上の交換率が得られることがあり、全ての銅イオンが１価として存在する場合が上限であり、そのときの計算上のイオン交換率は２００％となる。
【００１６】
このようなＣｕ−ＺＳＭ−５を微量不純物の吸着剤として使用することにより、例えば、希ガス、酸素、水素、二酸化炭素、炭化水素、六フッ化硫黄といったガス中に微量に存在する不純物、例えば、一酸化炭素、窒素、アンモニア、三フッ化窒素、二酸化炭素、メタン、水素、酸素を効率よく吸着除去して前記ガスを精製することができ、精製後のガス中に含まれる不純物量を１ｐｐｍ以下、すなわち、純度を９９．９９９９容量％以上にすることができる。
【００１７】
ガスの精製処理は、前記吸着剤を充填した吸着筒に精製対象ガスを流通させて該ガスと吸着剤とを接触させればよい。両者を接触させるときの温度は、常温、例えば１０〜４０℃の範囲でよく、特に冷却したりする必要はほとんどない。また、前記微量不純物を吸着した吸着剤は、適当な温度に加熱することにより、微量不純物を脱着させて吸着剤を再生することができる。したがって、相対的に低い温度で行う微量不純物の吸着工程と、相対的に高い温度で行う脱着工程（再生工程）とを交互に繰り返すことにより、吸着剤を繰り返して使用することができる。
【００１８】
さらに、図１の概略系統図に示すように、前記吸着剤（Ｃｕ−ＺＳＭ−５）を充填した吸着筒１０ａ，１０ｂを複数基設置するとともに、精製対象ガス用配管１１，１２と吸着剤再生ガス用配管１３，１４とをそれぞれ接続し、これらの配管にそれぞれ設けた遮断弁を所定の順序で開閉し、精製対象となるガスを相対的に低い温度に保たれた吸着筒に導入する吸着工程と、再生ガス加熱器１５で加熱した再生ガスを吸着筒に流通させながら相対的に高い温度で行う脱着工程とを複数の吸着筒１０ａ，１０ｂで交互に繰り返すことにより、精製対象ガス中の微量不純物を連続的に吸着除去することができる。
【００１９】
【実施例】
実施例１
シリカ対アルミナ比（Ｓｉ／Ａｌ比）が１１．９のナトリウム型ＺＳＭ−５ゼオライト（Ｎａ−ＺＳＭ−５）を、０．０１モル濃度の酢酸銅溶液中に浸漬して９０℃で１時間のイオン交換を行った。異なったイオン交換レベルのサンプルを得るため、この操作を数回繰り返すことにより、イオン交換率が０％，３６％，８３％，１２１％，１４７％の５種類を調製した。ＺＳＭ−５にイオン交換された銅の量は、ＩＣＰ発光分析により測定した。
【００２０】
吸着剤の評価として、定容法により吸着等温線の測定を行った。測定条件は、使用吸着剤量約０．５ｇ、吸着温度２５℃とし、吸着測定前に吸着剤の前処理として６００℃での真空加熱処理を行った。表１に、Ｃｕ−ＺＳＭ−５の銅イオン交換率と、吸着温度２５℃、平衡圧力１０Ｐａにおける一酸化炭素及び窒素の平衡吸着量との関係を示す。
【００２１】
【表１】
実施例２
シリカ対アルミナ比の異なる４種類のＺＳＭ−５ゼオライトに、実施例１と同じ銅イオン交換操作を施し、銅イオン交換率が概ね１２０％のＣｕ−ＺＳＭ−５を得た。吸着剤の評価として、実施例１と同様の方法で一酸化炭素及び窒素の吸着量をそれぞれ測定した。表２に、Ｃｕ−ＺＳＭ−５のシリカ対アルミナ比と、吸着温度２５℃、平衡圧力１０Ｐａにおける一酸化炭素及び窒素の平衡吸着量との関係を示す。
【００２３】
【表２】
実施例３
吸着剤としてＣｕイオン交換率１２０％、シリカ対アルミナ比１９．５のＣｕ−ＺＳＭ−５を選択し、真空下での焼成温度が窒素吸着に与える影響を調べた。
吸着剤の評価は、実施例１と同様の方法で窒素の吸着量を測定した。表３にＣｕ−ＺＳＭ−５の初期焼成温度と、吸着温度２５℃、平衡圧力１０Ｐａにおける窒素平衡吸着量との関係を示す。
【００２５】
【表３】
実施例４
本発明による吸着剤と、従来の吸着剤（比較例）とにおける一酸化炭素及び窒素の吸着量を比較した。本発明の吸着剤には、シリカ対アルミナ比が１９．５で、銅イオン交換率が１２０％のＣｕ−ＺＳＭ−５を選び、比較例としては、一酸化炭素及び窒素の吸着量が多いとされるＣａ−Ｘ型を選定した。各吸着剤の評価は、実施例１と同様の方法で一酸化炭素及び窒素の吸着量をそれぞれ測定した。
吸着測定前の吸着剤の前処理として、Ｃｕ−ＺＳＭ−５は７００℃で真空加熱処理を、Ｃａ−Ｘは、剤の安定上の理由から３５０℃で真空加熱処理をそれぞれ行った。図２にＣｕ−ＺＳＭ−５及びＣａ−Ｘへの一酸化炭素と窒素との吸着等温線を示すとともに、表４に各剤の吸着温度２５℃、平衡圧力１０Ｐａにおける一酸化炭素及び窒素の平衡吸着量の関係を示す。
【００２７】
【表４】
実施例５
吸着剤としてシリカ対アルミナ比１９．５、Ｃｕイオン交換率１２０％のＣｕ−ＺＳＭ−５を選択し、実施例１と同様の方法で一酸化炭素、窒素、一酸化二窒素、二酸化炭素、メタン、水素、酸素、クリプトン、ＣＦ４及びアルゴンの吸着等温線の測定を行った。吸着測定前に吸着剤の前処理として７００℃で真空加熱処理を行った。図３及び図４に、Ｃｕ−ＺＳＭ−５への各ガスの吸着等温線を示すとともに、表５に吸着温度２５℃、平衡圧力１０Ｐａにおける各ガス種の平衡吸着量の関係を示す。
【００２９】
【表５】
図３及び図４から明らかなように、Ｃｕ−ＺＳＭ−５で吸着除去しようとする一酸化炭素、窒素、一酸化二窒素及び酸素は、化学吸着的なラングミュア型吸着等温線を示している。一方、高純度に精製しようとするアルゴン、クリプトン等の希ガス類やＣＦ ４ は、物理吸着を示す典型的なヘンリー型吸着等温線を示しており、これらのガスは、吸着剤表面とは特異的相互作用を持たないことがわかる。これらのことから、Ｃｕ−ＺＳＭ−５に対して物理吸着性を有するガス中に存在する化学吸着性を有するガスを容易に除去できることがわかる。
【００３１】
さらに、吸着等温線から、各ガスのＣｕ−ＺＳＭ−５への吸着力の強さ、即ち除去されやすさは、一酸化炭素＞酸素＞＞一酸化二窒素、窒素＞二酸化炭素、メタン、水素＞＞クリプトン、ＣＦ４、アルゴンと推測され、同じ性質を示す二酸化炭素、炭化水素（メタン）、水素は、Ｃｕ−ＺＳＭ−５を吸着剤として用いることにより、これらのガス中から一酸化炭素、窒素、一酸化二窒素及び酸素を除去することが可能であり、逆に希ガス中からＣｕ−ＺＳＭ−５を用いてこれらのガスを吸着除去することも可能であることがわかる。
【００３２】
実施例６
１００ｇの剤を焼成するため、直径４０ｍｍ、高さ５００ｍｍのステンレス容器中にＣｕ−ＺＳＭ−５を投入し、焼成雰囲気（窒素又は空気）による吸着剤の初期活性化方法を検討した。本発明による吸着剤として、シリカ対アルミナ比１９．５、Ｃｕイオン交換率１２０％のＣｕ−ＺＳＭ−５を選び、８００℃で加熱処理を行った。吸着剤の焼成後に、実施例１と同様の方法で窒素の吸着量を測定した。表６にＣｕ−ＺＳＭ−５の焼成雰囲気と平衡圧力１０Ｐａにおける窒素吸着量との関係を示す。
【００３３】
【表６】
実施例７
破過したＣｕ−ＺＳＭ−５の再生後の吸着能力を確認するための実験を行った。まず、アルゴン中に微量窒素を含んだガスを使用してＣｕ−ＺＳＭ−５を一旦破過させた。すなわち、吸着筒として、内径２０ｍｍ、長さ５００ｍｍのカラムを使用し、シリカ対アルミナ比１９．５、Ｃｕイオン交換率１２０％のＣｕ−ＺＳＭ−５を６９．０ｇ充填した。測定ガスとして、アルゴン中に窒素５１２ｐｐｍを含むガスを使用し、これを２５℃、０．１９ＭＰａ、３．０Ｌ／ｍｉｎで吸着筒に流し、吸着筒出口における窒素の濃度変化を測定した。窒素濃度の測定は放電発光分光法で行い、破過時間は、出口濃度が入口濃度に対して５％に到達した時点とした。このときの経過時間と吸着筒出口窒素濃度との関係を図５に示す。
【００３５】
次に、上記操作で破過した剤を用いて再生実験を２度行った。すなわち、破過した剤を吸着筒外部から３５０℃で加熱再生し、その後、上記操作の場合と同じ条件で破過実験を２回繰り返した。実験の結果、３５０℃で再生した吸着剤の窒素破過時間は、再生１回目が８８分、再生２回目が９０分であり、上記操作での結果と略同じ時間となった。
【００３６】
実施例８
実験温度を４０℃とした以外は実施例７と同じ条件で破過実験を行った。実験の結果、窒素の破過時間は８２分であり、この剤の破過時間が実験温度には大きく影響されないことがわかった。
【００３７】
実施例９
測定ガス中の窒素濃度を９９ｐｐｍ、流速を０．５１Ｌ／ｍｉｎとし、その他は実施例７と同じ条件で破過実験を行った。実験の結果、窒素の破過時間は３５．８時間となった。
【００３８】
実施例１０
クリプトン中に微量窒素を含んだガスを使用してＣｕ−ＺＳＭ−５の破過実験を行った。吸着筒には、内径２０ｍｍ、長さ５００ｍｍのカラムを使用し、シリカ対アルミナ比１９．５、Ｃｕイオン交換率１２０％のＣｕ−ＺＳＭ−５を８７．４ｇ充填した。 測定ガスとして、クリプトン中に窒素約７９．８ｐｐｍを含むガスを使用し、これを２５℃、０．３５ＭＰａ、１．１Ｌ／ｍｉｎで吸着筒に流し、吸着筒出口における窒素の濃度変化を測定した。窒素濃度の測定は放電発光分光法で行い、破過時間は、出口濃度が入口濃度に対して２．５％に到達した時点とした。実験の結果、窒素の破過時間は３５．１時間となった。
【００３９】
実施例１１
アルゴン中に微量窒素を含んだガスを使用してＣｕ−ＺＳＭ−５の破過実験を行った。吸着筒には、内径２０ｍｍ、長さ５００ｍｍのカラムを使用し、シリカ対アルミナ比１９．５、Ｃｕイオン交換率１２０％のＣｕ−ＺＳＭ−５を８７．４ｇ充填した。測定ガスとして、アルゴン中に窒素５１２ｐｐｍを含むガスを使用し、これを２５℃、０．１５ＭＰａ、０．７６Ｌ／ｍｉｎで吸着筒に流し、吸着筒出口における窒素の濃度変化を測定した。窒素濃度の測定はガスクロマトグラフ−質量分析計（ＧＣ−ＭＳ）で行い、破過時間は、出口濃度が１ｐｐｍを超えた時点とした。実験の結果、窒素の破過時間は７．９時間となった。また、７．８時間経過時の出口窒素濃度は、検出限界の５ｐｐｂ以下であり、長時間極めて低い濃度まで窒素を吸着除去していることがわかった。
【００４０】
実施例１２
破過したＣｕ−ＺＳＭ−５の再生後の吸着能力を確認するための実験を、クリプトン中に微量の窒素及び酸素を含んだガスを使用して行った。すなわち、クリプトン中に微量の窒素及び酸素を含んだガスを使用してＣｕ−ＺＳＭ−５を一旦破過させた。吸着筒として、内径２０ｍｍ、長さ５００ｍｍのカラムを使用し、シリカ対アルミナ比１９．５、Ｃｕイオン交換率１２０％のＣｕ−ＺＳＭ−５を８７．４ｇ充填した。測定ガスとして、クリプトン中に窒素１４４２ｐｐｍ及び酸素１１ｐｐｍを含むガスを使用し、これを２５℃、０．１５ＭＰａ、０．３５Ｌ／ｍｉｎで吸着筒に流し、吸着筒出口における窒素の濃度変化を測定した。窒素濃度の測定はガスクロマトグラフ−質量分析計（ＧＣ−ＭＳ）で行い、破過時間は、窒素の出口濃度が１ｐｐｍを超えた時点とした。
【００４１】
この操作の結果、窒素の破過時間は６．２時間となった。また、６．０時間経過時の吸着筒出口における窒素及び酸素の濃度は、ともに検出限界の５ｐｐｂ以下であり、極めて低い濃度まで不純物ガスを除去していることがわかった。また、２種類の不純物ガスが混在していても、その両方を選択的に吸着除去できることがわかった。
【００４２】
次に、上記操作により破過した剤を用いて再生破過実験を１度行った。すなわち、破過した剤を、吸着筒外部から３５０℃で加熱再生した後、上記操作の場合と同じ条件で破過実験を行った。実験の結果、３５０℃で再生した後の吸着剤の窒素破過時間は、６．２時間であり、上述の操作結果と同じとなった。
【００４３】
【発明の効果】
以上説明したように、本発明によれば、ガス中の微量不純物成分を選択的に吸着除去することができるので、不純物として除去されるべき微量の不純物成分、例えばアンモニア、三フッ化窒素、二酸化炭素、水素及び酸素の単成分又はこれらの複数成分及び一酸化炭素、窒素、メタンを同時に吸着除去することができ、これらの不純物成分を含む高純度のガス、例えば、ヘリウム、ネオン、アルゴン、クリプトン、キセノン等の希ガスをはじめとして、酸素、水素、二酸化炭素、炭化水素ガス、炭化水素ガスの一部又は全部をハロゲンで置換したガス、六フッ化硫黄等を極めて高い純度で得ることができる。
【図面の簡単な説明】
【図１】 本発明のガス精製装置の一例を示す概略系統図である。
【図２】 実施例４での実験結果を示すＣｕ−ＺＳＭ−５及びＣａ−Ｘへの一酸化炭素と窒素との吸着等温線図である。
【図３】 実施例５での実験結果を示すＣｕ−ＺＳＭ−５への各ガスの吸着等温線図である。
【図４】 実施例５での実験結果を示すＣｕ−ＺＳＭ−５への各ガスの吸着等温線図である。
【図５】 実施例７での実験結果を示す経過時間と吸着筒出口窒素濃度との関係を示す図である。
【符号の説明】
１０ａ，１０ｂ…吸着筒、１１，１２…精製対象ガス用配管、１３，１４…吸着剤再生ガス用配管、１５…再生ガス加熱器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sorbent, particularly, high purity contained in the gas luer ammonia which is a refined gas, nitrogen trifluoride adsorbed, carbon dioxide, hydrogen, by selective adsorbent trace impurities such as oxygen The present invention relates to an adsorbent for removing gas to obtain ultra-high purity gas.
[0002]
[Prior art]
Inert gases such as helium, argon, krypton, xenon or nitrogen and various other gases are widely used in the electronics industry. Such inert gases used in the electronics field include those used in the semiconductor manufacturing process itself and those for general use that are used as purge or dilution gas in every process. The level of purity achieved varies greatly, but at least 99.999% or more is required.
[0003]
In particular, the gas used in the semiconductor manufacturing process has a strict requirement for purity, and each impurity amount is required to be at the ppb level. The gas to be removed as impurities in the gas used in the semiconductor manufacturing process is oxygen, carbon dioxide, water, carbon monoxide, hydrogen, hydrocarbons, or the like. Further, in the case of rare gases, nitrogen is also an object to be removed in addition to the impurities mentioned above.
[0004]
On the other hand, in the field of gas adsorption separation, zeolites such as Ca-A type, Na-X, and Ca-X type are generally known to adsorb nitrogen and carbon monoxide relatively well and are put to practical use. ing. However, the adsorption isotherms of these zeolites are almost linear in the low-pressure region, and the amount of adsorption to extremely low concentrations of nitrogen and carbon monoxide is small, so it is virtually impossible to use for purification at the ppm level. It was.
[0005]
JP-A-60-156548 uses a ZSM-5 type zeolite having a silica to alumina ratio of 19 or less and containing copper ions, and a gas from a gas containing a relatively high concentration of carbon monoxide. A method for recovering carbon oxide is disclosed. This method relates to an adsorbent that exhibits selectivity only to carbon monoxide and has a large adsorption capacity when separating and recovering carbon monoxide from a gas containing carbon monoxide at a relatively high concentration, There is no detailed explanation about the trapping method, and basically it does not suggest the possibility of removing carbon monoxide present as a trace impurity in the gas.
[0006]
Further, JP-A-61-18431 discloses that an adsorbent in which monovalent copper and / or silver is supported on a Y-type, A-type or X-type zeolite having a silica to alumina ratio of 10 or less, A technique for adsorbing and separating carbon monoxide from a mixed gas containing a relatively high concentration of carbon monoxide is disclosed. Carbon monoxide in the raw material gas shown in the examples described in the above publication is in a relatively high concentration range, and it is not mentioned about removal at the ppm level, and ZSM-5 is used as a basic adsorbent. There is no suggestion about.
[0007]
Japanese Patent Laid-Open No. 3-65242 discloses a method for producing a copper-zeolite catalyst in which a zeolite having a silica to alumina ratio of 5 to 1000 is supported by ion exchange and dried, and then the zeolite is reduced to a volume ratio of 0. It is disclosed that heat treatment is performed in an inert gas stream to which 0.05 to 0.5% of hydrogen is added. The zeolite used here is most preferably ZSM-5 zeolite, but the purification results show that the carbon monoxide concentration in the model gas is 0.11% by volume, and the purification rate is It is 50-75%, is not refined at the ppm level, and does not mention removal of nitrogen or the like.
[0008]
[Problems to be solved by the invention]
Thus, in the conventional adsorption technology, carbon monoxide, nitrogen, dinitrogen monoxide, nitrogen monoxide, nitrogen dioxide, ammonia, nitrogen trifluoride, carbon dioxide, methane, hydrogen, oxygen contained in trace amounts in the gas It is difficult to remove impurities such as these simultaneously, and in particular, there has been a problem that the level of impurity removal cannot be made extremely small in the ppm level. The present invention may luer ammonia contained in various gas, nitrogen trifluoride, carbon dioxide, hydrogen, and trace impurities such as oxygen are selectively adsorbed and removed to a ppm level or less ultrapure gas It is aimed to provide an adsorbent that can be used.
[0009]
[Means for Solving the Problems]
To achieve the above object, the adsorbent of the present invention, ammonia, nitrogen trifluoride, adsorbing and removing the trace impurities in the refined gas containing-carbon dioxide, at least one of hydrogen and oxygen as a trace impurity An adsorbent for the production of ZSM-5 type zeolite exchanged with copper ions, and adsorbing and removing at least one of carbon monoxide, nitrogen and methane in addition to the trace amount of impurities It is characterized by.
[0010]
First, the gas (purification target gas) that is a target for removing trace impurities according to the present invention is, for example, various gases including inert gas used in the electronics field as described above, and is representative. And various rare gases, hydrogen, oxygen, carbon dioxide, hydrocarbons, hydrocarbons in which part or all of hydrogen is substituted with halogen, sulfur hexafluoride, and the like. In the present invention, the purity of these gases after purification is 99.9999% by volume or more, that is, the total of components contained as impurities after purification is 1 ppm or less.
[0011]
The adsorbent is a zeolite obtained by copper ion exchange of sodium ions or the like of ZSM-5 type zeolite (hereinafter sometimes referred to as ZSM-5). In the following description, the zeolite subjected to the copper ion exchange may be referred to as “Cu-ZSM-5”. A commercially available material can be used as the ZSM-5 type zeolite to be a raw material before the copper ion exchange, but the silica to alumina ratio is desirably 5-50. When the silica-to-alumina ratio in ZSM-5 exceeds 50, the amount of copper ion exchange decreases and the amount of adsorption of trace impurities decreases. Also, ZSM-5 with a silica to alumina ratio of less than 5 is difficult to obtain.
[0012]
The copper ion exchange rate in Cu-ZSM-5 is preferably at least 40% or more of the ion exchangeable amount of each zeolite. This is because the ion-exchanged copper ions cause specific adsorption of nitrogen, carbon monoxide and the like. If the copper ion exchange rate is too small, specific adsorption performance will not be exhibited.
[0013]
The method for ion-exchanging sodium contained in ZSM-5 to copper is not particularly limited, and a conventionally known method can be employed. For example, sodium can be ion exchanged for copper by immersing ZSM-5 in an aqueous solution of a soluble salt of copper (nitrate, acetate, oxalate, hydrochloride, etc.). In this case, the copper ion exchange amount can be adjusted to a desired amount by selecting the concentration of the copper salt, the immersion time, the immersion temperature, the number of immersions, and the like.
[0014]
After ion exchange, it is ready for use by washing with water and baking at an appropriate temperature after drying. The drying temperature at this time is suitably about 100 ° C., and the firing temperature is suitably 350 ° C. or higher, particularly 500 to 800 ° C. in a nitrogen gas atmosphere. Since the specific adsorption performance of this adsorbent is considered to be manifested by the presence of monovalent copper ions, the change from divalent to monovalent is insufficient at a firing temperature of less than 500 ° C., and sufficient adsorption performance is exhibited. Conversely, at a temperature of 800 ° C. or higher, the zeolite structure itself may be destroyed.
[0015]
The amount of copper ions contained in the zeolite subjected to copper ion exchange can be measured by any method, and can be measured, for example, by ICP emission analysis (inductive charge emission analysis). In addition, the ion exchange rate in this invention is calculated | required from the assumption that one copper ion exchanges with two sodium ions. That is, at the time of ion exchange, it is assumed that copper ions exist as divalent. Actually, since monovalent copper ions are also present, an exchange rate of 100% or more may be obtained as a calculated value, and the upper limit is when all copper ions are present as monovalent. The upper ion exchange rate is 200%.
[0016]
By using such Cu-ZSM-5 as an adsorbent for trace impurities, for example, impurities present in trace amounts in gases such as rare gases, oxygen, hydrogen, carbon dioxide, hydrocarbons, sulfur hexafluoride, , carbon monoxide, nitrogen, ammonia, nitrogen trifluoride, carbon dioxide, methane, hydrogen, oxygen can be efficiently adsorbed removed to purify the gas, the amount of impurities contained in the gas after purification 1 ppm or less, that is, the purity can be 99.9999% by volume or more.
[0017]
The gas purification process may be performed by circulating the gas to be purified through an adsorption cylinder filled with the adsorbent and bringing the gas into contact with the adsorbent. The temperature at which both are brought into contact may be room temperature, for example, in the range of 10 to 40 ° C., and there is almost no need for cooling. Further, the adsorbent adsorbing the trace impurities can be regenerated by desorbing the trace impurities by heating to an appropriate temperature. Therefore, the adsorbent can be used repeatedly by alternately repeating the adsorption process of the trace impurities performed at a relatively low temperature and the desorption process (regeneration process) performed at a relatively high temperature.
[0018]
Further, as shown in the schematic system diagram of FIG. 1, a plurality of
[0019]
【Example】
Example 1
A sodium-type ZSM-5 zeolite (Na-ZSM-5) having a silica-to-alumina ratio (Si / Al ratio) of 11.9 was immersed in a 0.01 molar copper acetate solution at 90 ° C. for 1 hour. Ion exchange was performed. In order to obtain samples with different ion exchange levels, this operation was repeated several times to prepare five types with ion exchange rates of 0%, 36%, 83%, 121%, and 147%. The amount of copper ion exchanged with ZSM-5 was measured by ICP emission analysis.
[0020]
As an evaluation of the adsorbent, an adsorption isotherm was measured by a constant volume method. The measurement conditions were an adsorbent amount of about 0.5 g, an adsorption temperature of 25 ° C., and a vacuum heat treatment at 600 ° C. was performed as a pretreatment of the adsorbent before the adsorption measurement. Table 1 shows the relationship between the copper ion exchange rate of Cu-ZSM-5 and the equilibrium adsorption amounts of carbon monoxide and nitrogen at an adsorption temperature of 25 ° C. and an equilibrium pressure of 10 Pa.
[0021]
[Table 1]
Example 2
Four types of ZSM-5 zeolite having different silica to alumina ratios were subjected to the same copper ion exchange operation as in Example 1 to obtain Cu-ZSM-5 having a copper ion exchange rate of approximately 120%. As the evaluation of the adsorbent, the amounts of carbon monoxide and nitrogen adsorbed were measured in the same manner as in Example 1. Table 2 shows the relationship between the silica-to-alumina ratio of Cu-ZSM-5 and the equilibrium adsorption amounts of carbon monoxide and nitrogen at an adsorption temperature of 25 ° C. and an equilibrium pressure of 10 Pa.
[0023]
[Table 2]
Example 3
Cu-ZSM-5 having a Cu ion exchange rate of 120% and a silica-to-alumina ratio of 19.5 was selected as the adsorbent, and the influence of the firing temperature under vacuum on nitrogen adsorption was investigated.
The adsorbent was evaluated by measuring the amount of nitrogen adsorbed in the same manner as in Example 1. Table 3 shows the relationship between the initial firing temperature of Cu-ZSM-5 and the nitrogen equilibrium adsorption amount at an adsorption temperature of 25 ° C. and an equilibrium pressure of 10 Pa.
[0025]
[Table 3]
Example 4
The adsorption amounts of carbon monoxide and nitrogen in the adsorbent according to the present invention and the conventional adsorbent (comparative example) were compared. For the adsorbent of the present invention, Cu-ZSM-5 having a silica-to-alumina ratio of 19.5 and a copper ion exchange rate of 120% is selected. As a comparative example, the adsorbed amount of carbon monoxide and nitrogen is large. Ca-X type was selected. For the evaluation of each adsorbent, the amounts of carbon monoxide and nitrogen adsorbed were measured in the same manner as in Example 1.
As pretreatment of the adsorbent before the adsorption measurement, Cu-ZSM-5 was vacuum heat treated at 700 ° C., and Ca-X was vacuum heat treated at 350 ° C. for reasons of agent stability. FIG. 2 shows adsorption isotherms of carbon monoxide and nitrogen on Cu-ZSM-5 and Ca-X, and Table 4 shows the equilibrium of carbon monoxide and nitrogen at an adsorption temperature of 25 ° C. and an equilibrium pressure of 10 Pa for each agent. The relationship of adsorption amount is shown.
[0027]
[Table 4]
Example 5
Cu-ZSM-5 having a silica-to-alumina ratio of 19.5 and a Cu ion exchange rate of 120% was selected as an adsorbent, and carbon monoxide, nitrogen, dinitrogen monoxide, carbon dioxide, methane were produced in the same manner as in Example 1. , Hydrogen, oxygen, krypton, CF 4 and argon adsorption isotherms were measured. Before the adsorption measurement, vacuum heat treatment was performed at 700 ° C. as a pretreatment of the adsorbent. 3 and 4 show the adsorption isotherm of each gas on Cu-ZSM-5, and Table 5 shows the relationship between the equilibrium adsorption amount of each gas species at an adsorption temperature of 25 ° C and an equilibrium pressure of 10 Pa.
[0029]
[Table 5]
As apparent from FIGS. 3 and 4, carbon monoxide, nitrogen, dinitrogen monoxide and oxygen to be adsorbed and removed by Cu-ZSM-5 show chemisorbed Langmuir type adsorption isotherms. On the other hand, noble gases such as argon and krypton and CF 4 to be purified to high purity show typical Henry type adsorption isotherms showing physical adsorption, and these gases have a specific mutual relationship with the adsorbent surface. It can be seen that it has no effect. From these facts, it can be seen that the gas having the chemical adsorption property present in the gas having the physical adsorption property to Cu-ZSM-5 can be easily removed.
[0031]
Furthermore, the adsorption isotherm or al, the strength of the attractive force of the Cu-ZSM-5 of the gas, i.e., removed the easiness carbon monoxide> oxygen >> nitrous oxide, nitrogen> carbon dioxide, methane, Carbon dioxide, hydrocarbon (methane), and hydrogen, which are assumed to be hydrogen >> krypton, CF4, and argon and exhibit the same properties, can be obtained by using carbon monoxide from these gases by using Cu-ZSM-5 as an adsorbent, It can be seen that nitrogen, dinitrogen monoxide, and oxygen can be removed, and conversely, these gases can be removed by adsorption from a rare gas using Cu-ZSM-5.
[0032]
Example 6
In order to fire 100 g of the agent, Cu-ZSM-5 was put into a stainless steel container having a diameter of 40 mm and a height of 500 mm, and an initial activation method of the adsorbent by a firing atmosphere (nitrogen or air) was examined. As the adsorbent according to the present invention, Cu-ZSM-5 having a silica to alumina ratio of 19.5 and a Cu ion exchange rate of 120% was selected and heat-treated at 800 ° C. After the adsorbent was baked, the amount of nitrogen adsorbed was measured in the same manner as in Example 1. Table 6 shows the relationship between the firing atmosphere of Cu-ZSM-5 and the nitrogen adsorption amount at an equilibrium pressure of 10 Pa.
[0033]
[Table 6]
Example 7
An experiment was conducted to confirm the adsorption ability after regeneration of Cu-ZSM-5 that had passed through. First, Cu-ZSM-5 was once broken through using a gas containing a small amount of nitrogen in argon . That is, a column having an inner diameter of 20 mm and a length of 500 mm was used as an adsorption cylinder, and 69.0 g of Cu-ZSM-5 having a silica to alumina ratio of 19.5 and a Cu ion exchange rate of 120% was packed. A gas containing 512 ppm of nitrogen in argon was used as a measurement gas, and this was passed through the adsorption cylinder at 25 ° C., 0.19 MPa, 3.0 L / min, and the change in nitrogen concentration at the adsorption cylinder outlet was measured. The nitrogen concentration was measured by discharge emission spectroscopy, and the breakthrough time was the time when the outlet concentration reached 5% of the inlet concentration. The relationship between the elapsed time at this time and the nitrogen concentration at the outlet of the adsorption cylinder is shown in FIG .
[0035]
Next, a regeneration experiment was performed twice using the agent broken through in the above operation. That is, the breakthrough agent was heated and regenerated from outside the adsorption cylinder at 350 ° C., and then the breakthrough experiment was repeated twice under the same conditions as in the above operation . As a result of the experiment, the nitrogen breakthrough time of the adsorbent regenerated at 350 ° C. was 88 minutes for the first regeneration and 90 minutes for the second regeneration, which was substantially the same as the result in the above operation .
[0036]
Example 8
A breakthrough experiment was conducted under the same conditions as in Example 7 except that the experimental temperature was 40 ° C. As a result of the experiment, it was found that the breakthrough time of nitrogen was 82 minutes, and the breakthrough time of this agent was not greatly affected by the experimental temperature.
[0037]
Example 9
A breakthrough experiment was performed under the same conditions as in Example 7 except that the nitrogen concentration in the measurement gas was 99 ppm and the flow rate was 0.51 L / min. As a result of the experiment, the breakthrough time of nitrogen was 35.8 hours.
[0038]
Example 10
A breakthrough experiment of Cu-ZSM-5 was conducted using a gas containing a small amount of nitrogen in krypton. The adsorption cylinder was a column having an inner diameter of 20 mm and a length of 500 mm, and was filled with 87.4 g of Cu-ZSM-5 having a silica to alumina ratio of 19.5 and a Cu ion exchange rate of 120%. As the measurement gas, a gas containing about 79.8 ppm of nitrogen in krypton was used, and this was passed through the adsorption cylinder at 25 ° C., 0.35 MPa, 1.1 L / min, and the change in the nitrogen concentration at the adsorption cylinder outlet was measured. . The nitrogen concentration was measured by discharge emission spectroscopy, and the breakthrough time was the time when the outlet concentration reached 2.5% of the inlet concentration. As a result of the experiment, the breakthrough time of nitrogen was 35.1 hours.
[0039]
Example 11
A breakthrough experiment of Cu-ZSM-5 was performed using a gas containing a trace amount of nitrogen in argon. The adsorption cylinder was a column having an inner diameter of 20 mm and a length of 500 mm, and was filled with 87.4 g of Cu-ZSM-5 having a silica to alumina ratio of 19.5 and a Cu ion exchange rate of 120%. As a measurement gas, a gas containing 512 ppm of nitrogen in argon was used, and this was passed through the adsorption cylinder at 25 ° C., 0.15 MPa, 0.76 L / min, and the change in nitrogen concentration at the adsorption cylinder outlet was measured. The nitrogen concentration was measured with a gas chromatograph-mass spectrometer (GC-MS), and the breakthrough time was the time when the outlet concentration exceeded 1 ppm. As a result of the experiment, the breakthrough time of nitrogen was 7.9 hours. The outlet nitrogen concentration after 7.8 hours was 5 ppb, which is the detection limit, and it was found that nitrogen was adsorbed and removed to a very low concentration for a long time.
[0040]
Example 12
An experiment for confirming the adsorption ability after regeneration of the breakthrough Cu-ZSM-5 was conducted using a gas containing a small amount of nitrogen and oxygen in krypton . That is, by using the gas containing nitrogen and oxygen traces were once broken umbrella the Cu-ZSM-5 in krypton. A column having an inner diameter of 20 mm and a length of 500 mm was used as an adsorption cylinder, and 87.4 g of Cu-ZSM-5 having a silica to alumina ratio of 19.5 and a Cu ion exchange rate of 120% was packed. As a measurement gas, a gas containing 1442 ppm nitrogen and 11 ppm oxygen in krypton was used, and this was passed through the adsorption cylinder at 25 ° C., 0.15 MPa, 0.35 L / min, and the change in the concentration of nitrogen at the outlet of the adsorption cylinder was measured. . The nitrogen concentration was measured with a gas chromatograph-mass spectrometer (GC-MS), and the breakthrough time was the time when the nitrogen outlet concentration exceeded 1 ppm.
[0041]
As a result of this operation , the breakthrough time of nitrogen was 6.2 hours. Further, the nitrogen and oxygen concentrations at the adsorption cylinder outlet after 6.0 hours were both 5 ppb or less of the detection limit, and it was found that the impurity gas was removed to a very low concentration. Further, it was found that even when two kinds of impurity gases are mixed, both of them can be selectively adsorbed and removed.
[0042]
Next, a regeneration breakthrough experiment was performed once using the agent broken through by the above operation. In other words, the breakthrough was agent, after heating reproduced at 350 ° C. from the adsorption column outside, breakthrough experiments Tsu lines under the same conditions as in the above operation. As a result of the experiment, the nitrogen breakthrough time of the adsorbent after regeneration at 350 ° C. was 6.2 hours, which was the same as the above operation result.
[0043]
【The invention's effect】
As described above, according to the present invention, trace impurity components in the gas can be selectively adsorbed and removed. Therefore, trace impurity components to be removed as impurities, such as ammonia, nitrogen trifluoride, A single component of carbon, hydrogen and oxygen or a plurality of these components and carbon monoxide, nitrogen, and methane can be adsorbed and removed simultaneously, and a high-purity gas containing these impurity components, for example, helium, neon, argon, krypton In addition to rare gases such as xenon, oxygen, hydrogen, carbon dioxide, hydrocarbon gas, gas in which part or all of hydrocarbon gas is substituted with halogen, sulfur hexafluoride, etc. can be obtained with extremely high purity. .
[Brief description of the drawings]
FIG. 1 is a schematic system diagram showing an example of a gas purification apparatus of the present invention.
2 is an adsorption isotherm of carbon monoxide and nitrogen on Cu-ZSM-5 and Ca-X showing experimental results in Example 4. FIG.
3 is an adsorption isotherm of each gas on Cu-ZSM-5 showing the experimental results in Example 5. FIG.
4 is an adsorption isotherm of each gas on Cu-ZSM-5 showing the experimental results in Example 5. FIG.
FIG. 5 is a graph showing the relationship between the elapsed time and the adsorption tube outlet nitrogen concentration showing the experimental results in Example 7.
[Explanation of symbols]
10a, 10b ... Adsorption cylinders, 11, 12 ... Pipes for gas to be purified, 13, 14 ... Pipes for adsorbent regeneration gas, 15 ... Regeneration gas heater
Claims (5)
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| US9901900B2 (en) | 2014-11-13 | 2018-02-27 | Samsung Electronics Co., Ltd. | Gas-adsorbing material and vacuum insulation material including the same |
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