WO1999046782A2 - Ferromagnetic particles - Google Patents
Ferromagnetic particles Download PDFInfo
- Publication number
- WO1999046782A2 WO1999046782A2 PCT/NL1999/000116 NL9900116W WO9946782A2 WO 1999046782 A2 WO1999046782 A2 WO 1999046782A2 NL 9900116 W NL9900116 W NL 9900116W WO 9946782 A2 WO9946782 A2 WO 9946782A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- particles
- carbon
- metal
- ferromagnetic
- carbon fibrils
- Prior art date
Links
- 230000005294 ferromagnetic effect Effects 0.000 title claims abstract description 112
- 239000002245 particle Substances 0.000 title claims description 252
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 228
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 181
- 229910052751 metal Inorganic materials 0.000 claims abstract description 64
- 239000002184 metal Substances 0.000 claims abstract description 64
- 239000002923 metal particle Substances 0.000 claims abstract description 47
- 229910001092 metal group alloy Inorganic materials 0.000 claims abstract 2
- 239000003054 catalyst Substances 0.000 claims description 69
- 239000000463 material Substances 0.000 claims description 69
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 63
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 45
- 230000005291 magnetic effect Effects 0.000 claims description 43
- 229910045601 alloy Inorganic materials 0.000 claims description 39
- 239000000956 alloy Substances 0.000 claims description 39
- 238000002360 preparation method Methods 0.000 claims description 36
- 239000007788 liquid Substances 0.000 claims description 34
- 230000009467 reduction Effects 0.000 claims description 29
- 239000007789 gas Substances 0.000 claims description 26
- 229910052742 iron Inorganic materials 0.000 claims description 26
- 239000001257 hydrogen Substances 0.000 claims description 25
- 229910052739 hydrogen Inorganic materials 0.000 claims description 25
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 25
- 239000002243 precursor Substances 0.000 claims description 24
- 239000000243 solution Substances 0.000 claims description 24
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 23
- 229910002804 graphite Inorganic materials 0.000 claims description 23
- 239000010439 graphite Substances 0.000 claims description 23
- 150000002739 metals Chemical class 0.000 claims description 21
- 229910052759 nickel Inorganic materials 0.000 claims description 21
- 239000011149 active material Substances 0.000 claims description 19
- 229910017052 cobalt Inorganic materials 0.000 claims description 18
- 239000010941 cobalt Substances 0.000 claims description 18
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 18
- 238000011068 loading method Methods 0.000 claims description 18
- 239000011148 porous material Substances 0.000 claims description 18
- 239000000203 mixture Substances 0.000 claims description 17
- 239000000725 suspension Substances 0.000 claims description 16
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 15
- 150000002500 ions Chemical class 0.000 claims description 15
- 238000006243 chemical reaction Methods 0.000 claims description 14
- 238000000926 separation method Methods 0.000 claims description 14
- 239000002253 acid Substances 0.000 claims description 13
- 229910000510 noble metal Inorganic materials 0.000 claims description 13
- 150000001875 compounds Chemical class 0.000 claims description 12
- 239000007791 liquid phase Substances 0.000 claims description 12
- 230000005415 magnetization Effects 0.000 claims description 12
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 12
- 229920000642 polymer Polymers 0.000 claims description 12
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 11
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 11
- 238000005470 impregnation Methods 0.000 claims description 11
- 239000011261 inert gas Substances 0.000 claims description 11
- 230000003647 oxidation Effects 0.000 claims description 11
- 238000007254 oxidation reaction Methods 0.000 claims description 11
- 230000001590 oxidative effect Effects 0.000 claims description 10
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 9
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 239000010457 zeolite Substances 0.000 claims description 9
- 229910044991 metal oxide Inorganic materials 0.000 claims description 8
- 150000004706 metal oxides Chemical class 0.000 claims description 8
- 150000002825 nitriles Chemical class 0.000 claims description 8
- 238000001354 calcination Methods 0.000 claims description 7
- -1 cobalt-nickel -iron cyanides Chemical class 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 102000004169 proteins and genes Human genes 0.000 claims description 7
- 108090000623 proteins and genes Proteins 0.000 claims description 7
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 6
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 6
- 150000001450 anions Chemical class 0.000 claims description 6
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 6
- 238000005984 hydrogenation reaction Methods 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 6
- 238000001556 precipitation Methods 0.000 claims description 6
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 6
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 6
- 239000000377 silicon dioxide Substances 0.000 claims description 6
- 235000012239 silicon dioxide Nutrition 0.000 claims description 6
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 5
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 5
- QVYYOKWPCQYKEY-UHFFFAOYSA-N [Fe].[Co] Chemical compound [Fe].[Co] QVYYOKWPCQYKEY-UHFFFAOYSA-N 0.000 claims description 5
- 230000015572 biosynthetic process Effects 0.000 claims description 5
- 238000006555 catalytic reaction Methods 0.000 claims description 5
- 239000008103 glucose Substances 0.000 claims description 5
- 229910052750 molybdenum Inorganic materials 0.000 claims description 5
- 239000011733 molybdenum Substances 0.000 claims description 5
- 239000012071 phase Substances 0.000 claims description 5
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 238000009826 distribution Methods 0.000 claims description 4
- 239000000395 magnesium oxide Substances 0.000 claims description 4
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 4
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 4
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- NAVJNPDLSKEXSP-UHFFFAOYSA-N Fe(CN)2 Chemical class N#C[Fe]C#N NAVJNPDLSKEXSP-UHFFFAOYSA-N 0.000 claims description 3
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 claims description 3
- 150000001336 alkenes Chemical class 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 3
- 238000005342 ion exchange Methods 0.000 claims description 3
- 150000002894 organic compounds Chemical class 0.000 claims description 3
- 230000001376 precipitating effect Effects 0.000 claims description 3
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 2
- KRKNYBCHXYNGOX-UHFFFAOYSA-K Citrate Chemical compound [O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O KRKNYBCHXYNGOX-UHFFFAOYSA-K 0.000 claims description 2
- 229920000557 Nafion® Polymers 0.000 claims description 2
- 235000019253 formic acid Nutrition 0.000 claims description 2
- ZSSVQAGPXAAOPV-UHFFFAOYSA-K molybdenum trichloride Chemical compound Cl[Mo](Cl)Cl ZSSVQAGPXAAOPV-UHFFFAOYSA-K 0.000 claims description 2
- 239000011949 solid catalyst Substances 0.000 claims description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 2
- 239000010937 tungsten Substances 0.000 claims description 2
- 229910052721 tungsten Inorganic materials 0.000 claims description 2
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 claims 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims 1
- 239000005977 Ethylene Substances 0.000 claims 1
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 claims 1
- 230000002902 bimodal effect Effects 0.000 claims 1
- FQMNUIZEFUVPNU-UHFFFAOYSA-N cobalt iron Chemical compound [Fe].[Co].[Co] FQMNUIZEFUVPNU-UHFFFAOYSA-N 0.000 claims 1
- NVIVJPRCKQTWLY-UHFFFAOYSA-N cobalt nickel Chemical compound [Co][Ni][Co] NVIVJPRCKQTWLY-UHFFFAOYSA-N 0.000 claims 1
- 238000001816 cooling Methods 0.000 claims 1
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 claims 1
- 239000012968 metallocene catalyst Substances 0.000 claims 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims 1
- 238000006116 polymerization reaction Methods 0.000 claims 1
- 239000004408 titanium dioxide Substances 0.000 claims 1
- 229910001928 zirconium oxide Inorganic materials 0.000 claims 1
- 238000000034 method Methods 0.000 description 31
- 239000006249 magnetic particle Substances 0.000 description 19
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 14
- 239000003302 ferromagnetic material Substances 0.000 description 12
- UGKDIUIOSMUOAW-UHFFFAOYSA-N iron nickel Chemical compound [Fe].[Ni] UGKDIUIOSMUOAW-UHFFFAOYSA-N 0.000 description 9
- 239000000126 substance Substances 0.000 description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 8
- 238000005054 agglomeration Methods 0.000 description 7
- 230000002776 aggregation Effects 0.000 description 7
- 229910052763 palladium Inorganic materials 0.000 description 7
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- 229910000531 Co alloy Inorganic materials 0.000 description 6
- 238000005119 centrifugation Methods 0.000 description 6
- 238000001914 filtration Methods 0.000 description 6
- 239000000696 magnetic material Substances 0.000 description 6
- 239000000376 reactant Substances 0.000 description 6
- 229910021536 Zeolite Inorganic materials 0.000 description 5
- 239000011324 bead Substances 0.000 description 5
- 230000008901 benefit Effects 0.000 description 5
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 102000004190 Enzymes Human genes 0.000 description 4
- 108090000790 Enzymes Proteins 0.000 description 4
- 229910000640 Fe alloy Inorganic materials 0.000 description 4
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 4
- 239000007795 chemical reaction product Substances 0.000 description 4
- HGCIXCUEYOPUTN-UHFFFAOYSA-N cyclohexene Chemical compound C1CCC=CC1 HGCIXCUEYOPUTN-UHFFFAOYSA-N 0.000 description 4
- 238000000354 decomposition reaction Methods 0.000 description 4
- 230000003993 interaction Effects 0.000 description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-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
- 230000008569 process Effects 0.000 description 4
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 4
- 230000006641 stabilisation Effects 0.000 description 4
- 238000011105 stabilization Methods 0.000 description 4
- 239000007858 starting material Substances 0.000 description 4
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 3
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 3
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- 238000009835 boiling Methods 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 3
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 3
- 238000007600 charging Methods 0.000 description 3
- 229940090961 chromium dioxide Drugs 0.000 description 3
- IAQWMWUKBQPOIY-UHFFFAOYSA-N chromium(4+);oxygen(2-) Chemical compound [O-2].[O-2].[Cr+4] IAQWMWUKBQPOIY-UHFFFAOYSA-N 0.000 description 3
- AYTAKQFHWFYBMA-UHFFFAOYSA-N chromium(IV) oxide Inorganic materials O=[Cr]=O AYTAKQFHWFYBMA-UHFFFAOYSA-N 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 238000005538 encapsulation Methods 0.000 description 3
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- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 2
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- 239000012670 alkaline solution Substances 0.000 description 2
- 150000001412 amines Chemical class 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 239000004202 carbamide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- XLJKHNWPARRRJB-UHFFFAOYSA-N cobalt(2+) Chemical compound [Co+2] XLJKHNWPARRRJB-UHFFFAOYSA-N 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
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- 238000003487 electrochemical reaction Methods 0.000 description 2
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- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 description 2
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 2
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- 229910000480 nickel oxide Inorganic materials 0.000 description 2
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
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- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
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- 229910052703 rhodium Inorganic materials 0.000 description 2
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- 150000003839 salts Chemical class 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
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- 241000894007 species Species 0.000 description 2
- 150000004763 sulfides Chemical class 0.000 description 2
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- YONPGGFAJWQGJC-UHFFFAOYSA-K titanium(iii) chloride Chemical compound Cl[Ti](Cl)Cl YONPGGFAJWQGJC-UHFFFAOYSA-K 0.000 description 2
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- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
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- 229910001313 Cobalt-iron alloy Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 1
- 239000005751 Copper oxide Substances 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- 229910001289 Manganese-zinc ferrite Inorganic materials 0.000 description 1
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 1
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- 229910002651 NO3 Inorganic materials 0.000 description 1
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- VEQPNABPJHWNSG-UHFFFAOYSA-N Nickel(2+) Chemical compound [Ni+2] VEQPNABPJHWNSG-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/18—Carbon
-
- B01J35/33—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/16—Metallic particles coated with a non-metal
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/0036—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties showing low dimensional magnetism, i.e. spin rearrangements due to a restriction of dimensions, e.g. showing giant magnetoresistivity
- H01F1/0045—Zero dimensional, e.g. nanoparticles, soft nanoparticles for medical/biological use
- H01F1/0054—Coated nanoparticles, e.g. nanoparticles coated with organic surfactant
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/0036—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties showing low dimensional magnetism, i.e. spin rearrangements due to a restriction of dimensions, e.g. showing giant magnetoresistivity
- H01F1/0072—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties showing low dimensional magnetism, i.e. spin rearrangements due to a restriction of dimensions, e.g. showing giant magnetoresistivity one dimensional, i.e. linear or dendritic nanostructures
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/44—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of magnetic liquids, e.g. ferrofluids
- H01F1/442—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of magnetic liquids, e.g. ferrofluids the magnetic component being a metal or alloy, e.g. Fe
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C26/00—Alloys containing diamond or cubic or wurtzitic boron nitride, fullerenes or carbon nanotubes
- C22C2026/002—Carbon nanotubes
Definitions
- the invention relates to chemically inert ferromagnetic particles having dimensions of about 4 nm to 1 ⁇ m, which can be dispersed in liquids.
- the invention also relates to the preparation of such particles.
- the ferromagnetic particles can be utilized in so-called ferrofluids, where, through dispersion of small magnetic particles in liquids, magnetic forces can be exerted on these liquids.
- These ferromagnetic particles can also be used for biophysical or biomedical applications.
- Also considered, in particular, are analytic methodologies whereby certain biologically important molecules, macromolecules or cells can be separated. Proteins or, by means of proteins, cells, can be adhered to the ferromagnetic particles, and the proteins or cells can be separated with magnetic forces.
- Magnetic particles To remove toxic metals or radioactive components occurring in low concentrations from liquid flows, adsorption onto magnetic particles has also been proposed (L. Nunez and M.D. Kaminski, ChemTech September 1998, pp. 41-46). It has further been proposed to apply magnetic particles in NMR imaging techniques. In addition, the use of ferromagnetic particles for reprographic purposes has been proposed. It is also possible to selectively heat material adhered to the magnetic particles by exposing the material adhered to the magnetic particles to a suitable electric alternating field. A special application of magnetic particles according to the invention is as support for catalytically active materials or enzymes.
- catalytically active materials include inter alia catalytically active noble metals, such as platinum, palladium and rhodium, catalytically active metals, such as nickel, copper or iron, catalytically active oxides, such as manganese oxide and copper oxide, and catalytically active sulfides, such as cobalt sulfide.
- catalytically active noble metals such as platinum, palladium and rhodium
- catalytically active metals such as nickel, copper or iron
- catalytically active oxides such as manganese oxide and copper oxide
- catalytically active sulfides such as cobalt sulfide.
- homogeneous catalysts can be adhered to the ferromagnetic particles and in this way, after completion of the reaction, be readily separated from the reaction products. In particular, it is attractive to separate organometallic compounds with costly metals, used as homogeneous catalysts, and ligands, from liquids through adherence to ferromagnetic
- the active surface area per unit weight of the catalyst determines the activity.
- the surface area per unit weight of the catalyst in particles of at least 3 mm is too small to obtain the technically required activity.
- porous catalyst bodies are used.
- the internal surface of the catalyst bodies having minimal dimensions of about 3 ⁇ m is sufficiently large to obtain technically required activities. It is technically not easy to produce wear-resistant catalyst bodies of dimensions of, for instance, 3 to 10 ⁇ m on a large scale. Comparatively new is the production of such catalyst bodies by spray- drying. With this technique it is possible to manufacture porous bodies based on aluminum oxide or silicon oxide having dimensions of, for instance, from 3 to 10 ⁇ m. However, manufacturing porous bodies based on activated carbon, which is a widely used support for liquid phase reaction, is not possible in this way.
- ferromagnetic particles are used as catalytically active material or as support for catalytically active material, separation of the catalyst bodies is technically properly possible also in the case of particles of considerably smaller dimensions than about 3 ⁇ m.
- By applying an inhomogeneous magnetic field extremely small particles too can be readily separated from liquids.
- Very small particles can be employed then and transport impediments can thus be avoided.
- this is of great importance; avoiding transport impediments can lead to particularly attractive selectivities in liquid phase reactions.
- catalytic reactions are carried out in which at least one of the reactants is liquid and at least one of the other reactants is gaseous.
- the transport of the gaseous reactant to the catalyst surface can in many cases be rate-determining, especially when the solubility of the gas in the liquid is low.
- a deficiency of hydrogen on the catalyst surface can lead to unwanted reactions of partially hydrogenated intermediates.
- the catalyst bodies are made significantly smaller than the thickness of the laminar boundary layer around the gas bubbles which are passed through the liquid, a much faster transport of the gaseous reactant to the catalyst surface can be accomplished.
- the thickness of the laminar boundary layer can be set at about 10 ⁇ m, so that catalyst particles of dimensions less than 1 ⁇ m lead to a faster mass transfer from the gas bubbles to the catalyst surface.
- the presence of such small catalyst bodies is effective only if the catalyst bodies are not present in the liquid while agglomerated to clusters of particles .
- a last important application of ferromagnetic particles according to the invention is as electrodes for electrochemical reactions.
- a great drawback of state of the art electrodes is that either the surface accessible to reactants is small or the electric conductance of the electrode is low. Because a low electric conductance is highly objectionable, electrodes having relatively low surface areas are employed. For the application of electrochemical processes, this has always been a major drawback; electrochemical processes nearly always have a low production rate per unit volume, so that such processes are relatively costly.
- electrodes can be achieved in which a high surface area is combined with a high electric conductance .
- Ferromagnetic particles of dimensions of less than 1 ⁇ are prepared in many cases by grinding. However, this is a very costly method, since the material often needs to be ground for weeks on end. It will be clear that grinding can only be properly applied in the case of oxidic ferromagnetic materials; metals cannot be properly comminuted by grinding.
- An alternative is precipitation of small ferromagnetic particles. In general, the precipitation is carried out according to a method dating from the last century, whereby solutions of iron (II) and iron (III) are mixed at a pH maintained constant. What precipitates then is, at least for a part, magnetite, Fe 3 0 4 , which can be converted by a thermal treatment to the more stable maghemite, g-Fe 2 0 3 .
- a drawback of these ferromagnetic materials is the relatively high chemical reactivity; in many liquids, attack and dissolution of iron ions arises. Another drawback is that the ferromagnetic particles have a poor dispersibility . Owing to the magnetic forces, there is an attractive interaction between the particles, which cluster as a result. In the ferrofluids, this drawback has been recognized.
- a stabilization of suspensions of magnetic particles is accomplished in two ways. According to the first methodology, elongate molecules having a reactive group on one side are provided on the surface of the ferromagnetic particles. Detergents are a good example of such molecules. A polar head is adhered to the ferromagnetic particle, while a non-polar tail projects into the liquid.
- the non-polar portions of the molecules prevent the distance between the ferromagnetic particles from becoming small and hence the attractive force between the particles from becoming large. Polymer molecules are also used for this purpose.
- the second way of preventing clustering of ferromagnetic particles is to provide an electrostatic charge on the particles. If, for instance, a negative charge is provided on the particles, this leads to electrostatic repulsion between the particles, which dominates over the magnetic attraction. However, this requires proper control of the ionic strength of the suspension, since too high an ionic strength leads to neutralization of the electrostatic charge on the particles over a short distance. Also, the electrostatic charge on suspended particles is generally strongly dependent on the pH of the suspension, so that the pH must be properly controlled as well.
- binder monomeric amines, such as pyridine or 4-pyridine-ethanesulfonic acid.
- organic polymers which are soluble or dispersible in water. A series of such polymers are mentioned, such as polymers of acrylic acid, methacrylic acid and vinylsulfonic acid. Also mentioned are amides, such as vinyl pyrrolidone and acrylamide.
- 95/13874 enumerates a long series of ferromagnetic materials that are suitable for magnetic separation of material adhered thereto, such as magnetite, maghemite, chromium dioxide and manganese-zinc ferrite. Touched upon in addition is the possibility of using ferromagnetic metal particles, such as iron, nickel or cobalt, obtained by decomposition of the corresponding carbonyls. It is rightly noted, however, that owing to the high saturation magnetization, these particles have a strong tendency to agglomerate .
- EP 90420555 (Rhone-Poulenc Chimie) suggests covering ferromagnetic particles with polysilsesquioxane .
- U.S. 5,512,332 (Immunivest Corporation) mentions covering ferromagnetic particles with synthetic or naturally occurring polymers, including peptides or proteins. The latter patent focuses especially on the separation of biologically or biochemically important species. The bioanalytic application comes first here. This last application also dominates in U.S. Patent 5,536,644 (Behringwerke AG, Marburg, Germany), which focuses particularly on the separation of cells and microorganisms from aqueous liquids by binding them to ferromagnetic particles and separating the ferromagnetic particles in a magnetic field with a gradient.
- patent application WO 91/02811 of Immunicon Corporation addresses the stability of suspensions of magnetic particles and the redispersion of such particles.
- the magnetic particles are preferably covered with a biochemical or biologically active material.
- this patent application describes the preparation of oxidic magnetic particles in the presence of a component suitable for forming a layer on the magnetic particles which counteracts conglomeration of the magnetic particles. Also described is a preparation whereby agglomerates of small magnetic particles are broken up by contacting the suspension with compounds suitable therefor.
- Such compounds are polypeptides, proteins or antibodies.
- Porous beads of resin are prepared, in which the reagents needed are provided.
- the reagents needed are provided.
- the beads can now be manipulated with magnets.
- the authors prepared magnetite particles in the presence of polydivinylbenzene . In this way, provided that the magnetite was prepared by iron (II) with arylnitro groups, beads that could be magnetically manipulated were obtained.
- the charge-determining ions will mostly interfere with the groups that are to bind the species to be separated.
- Stabilization by molecules having long non-polar groups has drawbacks in catalytic applications. Such a stabilization works only if the stabilizing molecules are provided on the surface of the ferromagnetic particles in a relatively high density. Then it is only possible to provide the catalytically active components on the non-polar parts of the stabilizing molecules. Apart from possible transport hindrance due to the typically closely packed non-polar molecules, the adherence of catalytically active components to such molecules is mostly low. Technically, loss of small catalytically active particles in the liquid phase is virtually never acceptable. In addition to the above- mentioned contamination of the reaction products with the catalyst, this may lead to losses of costly catalytically active metals, such as rhodium.
- Magnetite and maghemite are attacked by water and react to form non-ferromagnetic hydrated iron oxides. In the presence of (weakly) acid aqueous solutions, the attack proceeds more rapidly. Chromium dioxide is not stable with respect to disproportionation to chromic oxide and chromium trioxide
- Chromium dioxide and the decomposition products are not resistant to acids and bases.
- the ferromagnetic particles obtained in this way are not completely surrounded by layers of carbon with a relatively inert graphite structure.
- aggressive molecules can relatively easily reach the surface of the magnetic phase and penetrate between the parts of the surface that are covered with layers of a graphite structure.
- the object of the present invention therefore, is to provide small ferromagnetic particles which are chemically inert.
- the desired particles are ferromagnetic metal particles which are completely covered with a layer of graphitic carbon.
- 'Graphitic' is described herein as consisting of layers of carbon atoms having a graphite structure, while the successive layers are not stacked according to the graphite structure.
- ferromagnetic metal particles so completely with a layer of carbon that the material exhibits chemically a greater inertness than carbon which, for instance as activated carbon, is used as catalyst support.
- activated carbon ferromagnetic particles provided with a layer of carbon can be affected only by strongly oxidizing agents .
- Complete coverage of the ferromagnetic particles can be demonstrated experimentally in a number of different ways. The most obvious way is treatment of the carbon-encapsulated particles with a non-oxidizing (strongly) acid solution. For this purpose, for instance hydrochloric acid, formic acid or acetic acid can be used. All metal particles that are not completely covered with carbon are thereby dissolved.
- the photoelectrons coming from the metal are completely absent in the spectrum in the case of thicker layers, and are present to an attenuated extent in the case of thinner layers.
- the magnitude of the adsorption of hydrogen can be established to determine the extent of coverage of the surface of the metal particles with carbon. Little or no hydrogen is adsorbed onto the carbon surface, whereas the metal surfaces take up a great deal of hydrogen.
- the chemisorption of carbon monoxide has been used for decades now.
- the magnitude of the amount of carbon monoxide chemisorbed at -78°C is calculated from the difference between the total amount of adsorbed carbon monoxide and the reversibly adsorbed amount of carbon monoxide. On carbon surfaces no chemisorption of carbon monoxide occurs.
- the thickness of the carbon layer can vary from about 1 nm to about 50 nm.
- the carbon layer enveloping the ferromagnetic metal particles consists of layers of carbon atoms having a graphitic structure, with the stacking of the layers being less ordered than in the case of graphite.
- the fact that the graphitic layers are mutually ordered to a lesser extent than in graphite does not alter the chemical stability of metal or alloy particles surrounded by such graphite layers.
- the size of the carbon-covered ferromagnetic metal particles can be chosen within wide limits. It is possible to use carbon-covered particles having dimensions of about 4 nm to 1 ⁇ m or more. With a view to different applications, it is of great significance that the size of the ferromagnetic particles can be properly controlled; it is then of importance that a relatively narrow particle size distribution of the ferromagnetic particles can be set.
- the size of the ferromagnetic particles is especially relevant in the separation of the particles. Relatively large particles having dimensions of about 0.1 to 1 ⁇ m can be efficiently separated with a magnetic field of a relatively weak gradient . When it is not of importance to work with extremely small particles having dimensions of, for instance,
- ferromagnetic particles having a dimension of, for instance, 0.5 ⁇ m or more. In that case, no costly facilities are needed to apply a magnetic field with a strong gradient to the liquid phase. Clearly, in that case the ferromagnetic material must not contain any smaller magnetic particles, since these particles will not be separated then.
- part of the invention is a mixture of relatively large ferromagnetic particles and much smaller ferromagnetic particles.
- a magnetic field without a strong gradient it is also possible with a magnetic field without a strong gradient to separate (extremely) small ferromagnetic particles along with a small fraction of large ferromagnetic particles.
- the smaller ferromagnetic particles then agglomerate around the large ferromagnetic particles.
- a suspended solid phase can be separated without utilizing an external magnetic field with a more or less strong gradient.
- the agglomerated particles generally sediment rapidly, while the agglomerates can also be separated by filtration or centrifugation.
- ferromagnetic particles can be fixed in a particular area in a reactor with an inhomogeneous magnetic field and a flow of reactants can be passed therethrough. This makes it possible to use a pseudo fixed catalyst bed which contains much smaller catalyst bodies than a conventional fixed catalyst bed. When in a conventional fixed catalyst bed the size of the bodies is made less than about 1 mm, the pressure drop over the catalyst bed becomes too high, which causes channeling or results in the catalyst bed being pushed partly or wholly out of the reactor.
- agglomeration of the ferromagnetic particles is disadvantageous.
- the activity of the suspended catalytically active particles decreases considerably through agglomeration.
- Agglomeration of suspended ferromagnetic particles is caused especially by the permanent magnetic moment of small ferromagnetic particles. To prevent agglomeration of the ferromagnetic particles, it is therefore necessary that the ferromagnetic particles have no permanent magnetic moment.
- the dimensions at which monodomain behavior occurs in isotropic particles depend on the saturation magnetization and the magnetocrystalline anisotropy energy.
- the magnetocrystalline anisotropy causes the energy of a magnetical domain or of a monodomain particle to vary with the orientation of the magnetization with respect to the crystal lattice. This anisotropy derives from the spin orbit coupling.
- isotropic iron particles for the limit of monodomain behavior, a size of about 10 nm is specified.
- the limit for monodomain behavior lies at larger particle dimensions, viz. in excess of 20 nm.
- the magnetocrystalline anisotropy energy of a ferromagnetic particle is, of course, proportional to the volume of the particle.
- the anisotropic energy can become of the order of the thermal energy.
- the orientation (not the magnitude) of the magnetic moment of such particles now varies spontaneously, analogously to the Brownian movement of molecules and colloidal particles. According as the temperature is higher, the direction of the magnetic moment of a particle varies faster.
- the magnetic properties of such a collection of ferromagnetic particles are analogous to those of a paramagnetic material having a very high atomic magnetic moment, the material is referred to in that case as a superparamagnetic material .
- multidomain particles are used or superparamagnetic particles.
- the presence of multidomain particles can be determined by measuring the remanence of the particles. For multidomain particles, this remanence lies below 30 to 40% of the saturation magnetization. Superparamagnetic particles do not exhibit any remanence at all. Therefore, according to the invention, as properly dispersible bodies, ferromagnetic particles are used, the remanence of which is less than 30 to 40% of the saturation magnetization, preferably less than 20% of the saturation magnetization, and more preferably less than 10% of the saturation magnetization.
- alloys of a low magnetocrystalline anisotropy energy are used.
- alloys of iron and nickel or of cobalt and iron very low anisotropy energies can be obtained.
- iron-nickel or iron-cobalt alloy particles according to the invention will be used.
- the preparation of iron-nickel alloys can be carried out according to the prior art as described hereinbelow for iron-cobalt alloys. In view of the high saturation magnetization of iron-cobalt alloys, this is an attractive combination. In view of the price of cobalt, however, it can often be more economic to work with iron- nickel alloys.
- ferromagnetic particles of the desired metal or the desired alloy having the desired dimensions are provided on a support material conventional for heterogeneous catalysts, such as silicon dioxide, aluminum oxide or magnesium oxide.
- a support material conventional for heterogeneous catalysts, such as silicon dioxide, aluminum oxide or magnesium oxide.
- the reduction of metal oxides provided on support materials, according to the method of the present invention leads to isotropic particles.
- this is done in a manner known in the prior art, by providing optionally hydrated oxides of the desired metals on the support. It is most obvious to do this by impregnation of the support material with solutions of suitable salts of the metal to be provided or, in the case of alloys, of the metals to be provided.
- the oxide is reduced to the corresponding metal.
- the reduction is carried out by heating the loaded support in a flow of a hydrogen-containing gas mixture.
- nickel because of the position of the thermodynamic equilibrium, is relatively simple, the reduction of cobalt and especially that of iron must be carried out under properly controlled conditions.
- the water vapor pressure in the pores of the support must be kept low in the reduction.
- the reduction stops because of the position of the thermodynamic equilibrium at magnetite, Fe 3 0 4 . If the interaction with the support is strong, the reduction stops at wustite, FeO.
- the reduction of the metal oxide provided on the support can also be carried out in a different way, with other reducting agents.
- the dimensions of the resulting metal particles are determined by the loading of the support material , the specific surface area of the support material, and the temperature at which the supported metal particles are eventually treated in a non-oxidizing environment.
- a high loading of a support with a relatively low specific surface area and a treatment at a high temperature naturally lead to large metal particles, whereas a low loading of a support with a relatively large specific surface area and treatment at a relatively low temperature result in small to very small metal particles.
- the carbon layer is provided around the metal particles by exposing the supported metal particles at elevated temperature to a gas flow which contains carbon- containing molecules.
- the support material is removed by treating the material pre-treated in the above-mentioned manner, with a suitable acid or base.
- a suitable acid or base e.g., an aluminum oxide or magnesium oxide support will preferably be removed by treatment with acid, although aluminum oxide can also be removed by treatment with lye. It has been found that the treatment with a non-oxidizing acid does not affect the metal completely surrounded by graphite layers, but solely dissolves the support. Silicon dioxide is preferably removed by treatment with lye.
- the magnetic material according to the present invention is essentially distinghuised from the material described in
- the starting material is a powder of metallic iron, cobalt or nickel or alloys of these metals.
- the particles of the powder have a size of 0.5 mm or less.
- these particles are heated in a flow of carbon monoxide and hydrogen at a temperature of 150 to 400°C or in a flow of methane or ethane at a temperature of 300 to 500°C.
- such metal particles must be processed to form mechanically strong agglomerates of a size of at least 1 mm to make it possible to pass a gas flow through a packed bed of the particles whereby all particles come into contact with the gas flow.
- agglomerates of particles such as are to be used in a fixed bed or a fluidized bed, sinter very strongly. This holds in particular for nickel particles in the presence of carbon monoxide. Transport of nickel as nickel carbonyl then leads to a very strong and rapid sintering. In the manner described, it is therefore not possible to obtain small graphite-covered metal particles.
- ferromagnetic particles with a very high saturation magnetization it is attractive to use iron and in particular iron-cobalt alloys as ferromagnetic component.
- iron (II) Upon heating, the iron (II) is oxidized by the nitrate ions to iron (III) , which hydrolyzes and precipitates with the cobalt or with iron (II) as CoFe 2 0 4 and Fe (II) Fe (III) 2 0 4 .
- the hydrolysis of urea leads to
- particles of iron or of alloys of cobalt and iron or of nickel and iron or of all three metals mentioned are prepared starting from complex cyanides of iron.
- Iron particles are obtained according to the preferred method by precipitating complex iron cyanides by addition of dissolved iron (II) compounds to, for instance, (NH 4 ) 4 Fe (CN) 6 .
- II dissolved iron
- CN CN
- Precipitation of complex iron cyanides, having as the tetravalent or trivalent anion Fe(CN) 6 , or having Fe(CN) 5 (NO) as anion with nickel and/or cobalt makes it possible to prepare small alloy particles of a uniform chemical composition. The reduction of such complex cyanides proceeds very readily.
- the cyanides prior to the reduction to the alloy, must first be converted into the corresponding mixed oxides by calcining in an oxidizing gas flow.
- Large alloy particles are obtained by immediately heating the complex cyanides provided on a support in a reducing gas flow. Analysis of the chemical composition of the resulting individual alloy particles in the electron microscope has demonstrated that a highly uniform chemical composition of the particles is obtained.
- the particles according to the invention can be employed with much advantage for a number of technically important processes. As discussed above, the most obvious application is as support for catalytically active materials. It is also possible to adsorb compounds or elements onto the carbon surface and subsequently separate those with the particles. It is further possible to provide certain protein molecules on the carbon surface and subsequently to separate the magnetic particles or determine the location of the magnetic particles with a magnetic sensor.
- Such clusters of carbon fibrils are also highly suitable as support for suspended catalytically active materials. Separation by magnetic route is eminently possible with such clusters of carbon fibrils in which one or more ferromagnetic particles are present.
- Such carbon fibrils and the preparation thereof are disclosed, for instance, in U.S. 5,171,560 in the name of Hyperion Catalyst International.
- it is possible to grow carbon fibrils where the graphite layers are oriented at an angle to the fibril axis see U.S. 4,855,091 8 August 1989 in the name of DOW Chemical. If such an orientation of the graphite layers is involved, this is sometimes referred to as a fishbone structure.
- the mechanical strength of thin carbon fibrils with a fishbone structure is lower than that of carbon fibrils where the graphite layers are oriented parallel to the fibril axis.
- the mechanical strength is particularly the tensile strength; the compression strength of the two kinds of carbon fibrils does not differ appreciably.
- 'Thin' in this case means a diameter of the fibril of about 50 nm at a maximum.
- thick carbon fibrils having a fishbone structure prove to have a mechanical strength which is considerably higher than that of fibrils having a parallel orientation of the graphite layers, which can only be grown as thin fibrils.
- a thick carbon fibril is a fibril having a diameter of about 50 nm or more.
- An advantage of carbon fibrils having a fishbone structure is that the surface contains more reactive sites than the surface of carbon fibrils where the graphite surfaces are oriented parallel to the fibril axis. Also, potassium can be intercalated in such fibrils, which opens a number of application possibilities of interest.
- mechanically strong bodies of carbon fibrils are obtained by growing carbon fibrils with a fishbone structure of a diameter of at least about 50 nm.
- Such thick fibrils are generally not straight, but highly tortuous.
- the interweaving of the fibrils thereby caused leads to a high mechanical strength of the clusters of carbon fibrils.
- Such bodies of carbon fibrils having a fishbone structure form part of the invention.
- the size of the bodies can be governed by controlling the time during which the carbon fibrils grow. By abruptly increasing the thermodynamic potential of the carbon in the gas atmosphere, the metal particles from which the carbon fibrils grow encapsulate, so that growth stops. In this way, it is possible to grow bodies of dimensions of less than 1 ⁇ m to a few mm's or more.
- the above-mentioned special form of the material according to the invention also encompasses mechanically strong clusters of carbon fibrils having a fishbone structure, while the size of the clusters is greater than 3 ⁇ m.
- the content of ferromagnetic material is then much lower than in the materials discussed earlier.
- the clusters are allowed to grow to dimensions of 3 ⁇ m or more, actually no magnetic material is needed for separation, since the clusters can then be readily separated by sedimentation, filtration or centrifugation. It is possible to have the growth of the carbon fibrils proceed such that the ferromagnetic material is hardly, if at all, encapsulated. Subsequently, the magnetic material can be removed, if desired, by dissolving in acid.
- the accessible surface and the pore volume of thick carbon fibrils having a fishbone structure may be too small.
- bodies which contain both thin and thick carbon fibrils, while the thin carbon fibrils can have the graphite layers oriented both parallel to the fibril axis and at an angle, and the thick carbon fibrils have a fishbone structure.
- the accessible surface and the pore volume are then provided by the thin fibrils and the mechanical strength by the thick carbon fibrils.
- such clusters of thin and thick carbon fibrils having a fishbone structure' are produced by starting from support materials conventional in solid catalysts, which are loaded with metal or alloy particles of different dimensions.
- metal or alloy particles of different dimensions can also be obtained by mixing two support materials each loaded with more or less uniform metal or alloy particles which differ appreciably for the two supports.
- the starting material are metal or alloy particles of more than 30 nm and of less than 20 nm. From the work of Hoogenraad (M.
- a special embodiment of the material according to the invention comprises mechanically strong clusters of carbon fibrils, while the size of the clusters is greater than 3 ⁇ m. For the mechanical strength, these clusters contain thick carbon fibrils, the graphite layers of which are ordered according to a fishbone structure.
- a mixture of small and large supported metal or alloy particles is obtained by preparing the starting materials separately.
- a support By high-loading a support with a precursor of the metal or the alloy, large particles are obtained, after reduction, while a low loading leads to small particles.
- a condition is that in both cases the support is uniformly loaded with the active precursor.
- a number of methods are known for this purpose, such as deposition-precipitation or impregnation with citrate complexes.
- the starting point is conglomerates of support particles not greater than 1 mm, preferably not greater than 0.5 mm and more preferably not greater than 0.2 mm.
- the support particles After the loading with the precursor of the metal or the alloy, the support particles are suspended in a liquid, preferably in water, whereafter the suspension is properly mixed. After separation of the liquid and drying and, if necessary, calcining, the loaded support particles are formed into bodies of the dimensions desired for the growth of carbon fibrils.
- the desired ratio of thick and thin carbon fibrils is determined by the desired surface area and pore volume and the required mechanical strength. According to the invention, the mass ratio of large and small metal particles is varied from about 2:1 to 1:100.
- a mixture of fibrils having a fishbone structure and a parallel structure can be prepared.
- a metal or alloy is selected from which, under specified conditions, fibrils having a fishbone structure grow, such as, for instance, nickel, and a metal or alloy from which parallel fibrils grow, such as, for instance, iron.
- fibrils having a parallel orientation of the graphite layers can be grown from nickel particles.
- a mixture of nickel- and iron-loaded support particles is prepared according to the invention as described above.
- the mass ratio of the metal particles that grow thick carbon fibrils having a fishbone structure and thin carbon fibrils having a parallel structure is likewise varied from about 2:1 to about 1:100.
- the carbon fibrils having a fishbone structure prove to have a high electric conductance.
- This conductance has been established by providing the carbon fibrils on an aluminum table as used in scanning electron microscopy.
- a low conductance of a preparation leads to local charging of the preparation at those positions where contact with the aluminum of the preparation table is poor.
- the parts of the preparation that make poor contact with the aluminum preparation table are negatively charged.
- the electrons are incident on the negatively charged parts of the preparation at a lower velocity.
- the intensity of the secondary electrons increases strongly with decreasing energy of the incident electrons . In the picture of the secondary electrons, the negatively charged parts of the preparation are thus recognizable by a much higher intensity of the secondary electrons.
- polymers are therefore obtained having an electric conductance considerably higher than that of the pure polymer, by processing into the polymers carbon fibrils having a fishbone structure or a mixture of intertwined thick carbon fibrils having a fishbone structure and thin carbon fibrils having a parallel or fishbone structure.
- Such processing is done by the use of techniques known per se, such as, for instance, master batching, or mixing the carbon fibrils with the polymer powder, followed by extrusion.
- the invention therefore encompasses polymers into which carbon fibrils having a fishbone structure have been processed.
- the use as support for catalytically active materials has been mentioned.
- the material is used as support for catalytically active components.
- a (precursor of a) catalytically active material is provided on the carbon surface.
- methodologies can be used which are known according to the prior art for providing (precursors of) catalytically active materials on activated carbon.
- activated carbon oxidizes relatively rapidly upon exposure to the air.
- the surface of activated carbon after exposure to the air for about 24 hours contains many polar groups, such as carboxyl groups, to which precursors of catalytically active materials adsorb strongly.
- activated carbon is hydrophilic.
- polar groups such as carboxyl groups
- precursors of catalytically active materials can be readily adsorbed and thus catalytically active materials can be provided on the surface of activated carbon.
- the surface of the carbon layers according to the invention oxidizes much less fast. Indeed, the encapsulated ferromagnetic particles and the (clusters of) carbon fibrils are hydrophobic.
- a mild oxidation a limited number of carboxyl groups can be provided on the surface on the material according to the present invention, to which positively charged (precursors of) active components, such as ammonia complexes of noble metals, can be adsorbed.
- a mild oxidation can be performed, for instance, according to the prior art by suspending the encapsulated particles in diluted nitric acid and boiling for a short time. According to the prior art, other mild oxidation procedures, such as oxidation with hypochlorite, are also known. Upon prolonged boiling, the typically thin carbon layer is oxidized completely and the metal or alloy particles dissolve.
- Eminent results are also obtained by reducing dissolved compounds of noble metals, preferably complexes with ammonia or amines, in the liquid phase in the presence of suspended encapsulated particles.
- a very fine distribution of the active metal results when the reduction is performed at a temperature lower than that at which the reduction in the liquid phase in the absence of suspended encapsulated particles proceeds.
- this is done by loading mildly oxidized fibrils with a relatively small amount of a (precursor of an) active component. In general, such a loading is below 2% by weight and after reduction metal particles are obtained having dimensions of about 1 nm.
- the primarily provided catalytically active particles can be selectively grown into larger particles.
- active materials consisting of several components with a uniform composition of the active particles.
- a preferred method according to the invention is used.
- the carbon fibrils are impregnated with a solution of sugar or glucose, after which the impregnated carbon fibrils are dried.
- the resultant layer of sugar is decomposed at elevated temperature in an inert gas or an inert gas flow.
- a thin, strongly adherent layer of amorphous carbon on the carbon fibrils having an oxygen content depending on the decomposition temperature. This layer oxidizes fast upon exposure to atmospheric air, so that hydrophilic fibrils are obtained, which strongly adsorb complexes, for instance chloride complexes, of, for instance, noble metals.
- the noble metals can be reduced in an aqueous phase with formaldehyde or glucose or by passing hydrogen through the suspension.
- precursors of active components are provided on the surface of the materials according to the invention by impregnation with solutions of complexes of organic compounds, such as EDTA or citric acid. It is also possible first to provide surface-active compounds on the surface of the materials according to the present invention and then to provide the active components on the pre-treated surface. Often, the precursors of the active component (s) can advantageously be added to a solution of glucose or sugar. Upon drying of materials impregnated with such solutions, a viscous layer is formed on the carbon surface of the materials according to the present invention.
- the organic material is removed by heating the loaded support material in an oxygen-containing gas or an oxygen-containing gas flow.
- Such a method cannot be used with the support materials according to the present invention, since in that case the carbon is also oxidized from the support. This holds the more so since the (precursors of the) catalytically active materials in general also catalytically accelerate the oxidation of the carbon fibrils and carbon layers of the material according to the present invention.
- the organic ingredients of the impregnated material are removed by heating the loaded supports in an inert gas flow at a high temperature.
- the catalytically active components then generally remain behind, together with residues with a high carbon content, which largely cover the active components.
- the carbon-containing residues can be removed.
- carbon-containing supports such as the support materials according to the present invention, will be used as support for metallic active components.
- a reduction treatment is necessary to convert the precursor (s) of the active component (s) to the corresponding metals or alloys.
- noble metals can be reduced at a very low temperature, at which the carbon of the support does not react.
- noble metals In the case of noble metals, heating in an inert gas flow, such as argon or nitrogen, nearly always suffices. In that case, the metal is at least partly reduced by the carbon of the fibrils. In general, this involves only a relatively minor amount of carbon. Therefore, according to a special embodiment of the method according to the invention, noble metal precursors provided on the carbon fibrils are reduced by heating in an inert gas or an inert gas flow.
- Support materials according to the invention are particularly attractive as supports of catalytically active materials for hydrogenating desulfurization, denitrogenation or the hydrogenating removal of metals from crude oil fractions.
- cobalt and molybdenum containing catalysts are used for hydrogenating desulfurization, while nickel and tungsten catalysts are suitable for removing nitrogen from petroleum fractions.
- a great advantage of support materials according to the invention is that in the spent catalysts the carbon support can be readily oxidized off. The residual components can then be processed comparatively easily, in contrast to catalysts according to the prior art, where aluminum oxide is used as support.
- pretreating the carbon fibrils with Cl 2 at elevated temperature is recommendable. It is also possible to provide a thin layer of amorphous, oxygen- containing carbon by decomposing glucose or sugar, as described above. If carbon fibrils loaded in such a manner are used for polymerizing olefins, olefins are obtained of a sufficient electric conductance to prevent electrostatic charging. Also metallocenes can be provided on the carbon fibrils and in this way suitable pol merization catalysts can be obtained.
- zeolites for use as acid catalysts on the carbon fibrils according to the invention.
- a surface-active substance is provided on the surface of the carbon fibrils, whereafter the pretreated carbon fibrils are introduced in a synthesis suspension of zeolites.
- a great advantage is that in this way a large area to volume ratio of the zeolite is realized, so that transport impediments are entirely avoided.
- liquid phase reactions it is often cumbersome to separate the small zeolite crystallites, after reaction, from the liquid.
- separation of the zeolites from the liquid can be very readily effected by filtration or centrifugation.
- the carbon fibrils, after loading with the zeolite can be burnt away. Now, the inner surface of the zeolite layer is also accessible from the gas or the liquid phase. The mechanical strength of the system, however, is then less.
- a drawback of the carbon fibrils according to the present invention is that the fibrils are not resistant to an oxidizing environment at elevated temperature.
- the carbon fibrils are therefore converted into silicon carbide fibrils.
- a sealing layer of silicon oxide is formed, which prevents further oxidation.
- the conversion of the carbon fibrils to silicon carbide can be carried out according to the known prior art.
- the fibrils are heated in a flow of silicon monoxide.
- the relatively volatile silicon monoxide is obtained by heating silicon with silicon dioxide.
- Carbon fibrils converted to silicon carbide in this way are, according to the invention, an excellent catalyst support.
- also volatile halogen silanes can be used for the reaction to silicon carbide .
- the carbon fibrils according to the invention form an excellent support for ion exchangers.
- the large pore volume and the wide pores render this material eminently suitable for providing ion exchangers.
- ion exchangers can be obtained by mild oxidation, which leads to the presence of carboxyl groups on the carbon surface .
- More strongly acid ion exchangers can be obtained by reaction with sulfuric acid, as is known according to the prior art for carbon.
- known ion exchangers can be provided on the surface of the materials according to the invention.
- ion exchangers based on polystyrene are suitable for provision on the carbon fibrils.
- Nafion can be provided on the materials according to the invention.
- the carbon fibrils thus loaded with ion exchangers can be used well in a fixed bed, whereby a great fraction of the ion exchanging groups can be utilized. It is also possible to suspend the loaded fibrils and subsequently separate them through filtration or centrifugation. Highly attractive is the use of clusters of carbon fibrils in which encapsulated ferromagnetic particles are present which can quite readily be kept suspended in a flowing liquid or can be very easily separated by applying a magnetic field.
- Carbon fibrils loaded with ion exchangers are eminently applicable as acid catalysts.
- the poor transport properties of the ion exchangers according to the conventional prior art and the relatively low thermal stability are strongly improved by their provision on carbon fibrils .
- the pressure drop over the reactor is often of critical importance.
- the pressure drop is determined by the size of the bodies of the catalyst. In general, in a fixed catalyst bed, bodies of at least a few mm will be used to keep the pressure drop within acceptable values. Also when using ion exchangers in a fixed bed, it is of significance to use sufficiently large bodies. According to the invention, bodies of dimensions of a few mm's or more are then grown from the support materials loaded with metal or alloy particles. In that case, the conditions during the growth of the carbon fibrils are set such that relatively long thick carbon fibrils grow.
- bodies of a few mm's chiefly consisting of carbon fibrils can be obtained by starting from bodies of a suitable catalyst support, such as aluminum oxide or silicon oxide, of a few mm's. On the (internal) surface of these porous particles, the metal particles are provided from which it is desired to grow the carbon fibrils. Now, if the carbon fibrils are then allowed to grow, mechanically strong bodies having slightly greater dimensions than the original support bodies are obtained. According to the invention, bodies are used then which consist of conventional catalyst supports in which carbon fibrils have been grown which at the same time cover the external surface of the original support particles. According to the invention, such support particles are obtained by providing support bodies with metal particles of dimensions between about 5 nm and 0.2 mm and growing carbon fibrils therefrom.
- Part of the invention are electrodes obtained by introducing metal particles covered with carbon layers or carbon fibrils coupled to encapsulated metal particles, into a magnetic field, which keeps the particles oriented according to the lines of magnetic force. Owing to the gradient of the magnetic field, the particles are held at the desired position, while further a good contact between the particles is obtained.
- the electric conductance of the ferromagnetic metals is high, as is that of the carbon layers and the carbon fibrils. In this way, a well conducting electrode having a high specific surface is obtained.
- Another application of ferromagnetic particles completely covered with graphitic carbon layers is as electrode for electrochemical reactions. In certain cases, no other active components need to be provided on the carbon surface then. It has been found that such an electrode is eminently suitable for the electrochemical production of diluted hydrogen peroxide solutions.
- the catalyst was suspended in toluene, whereafter hydrogen was passed through to reduce again the palladium particles oxidized in the air. Then cyclohexene was injected into the suspension. The hydrogenation rate was determined by measuring the hydrogen consumption. The hydrogen consumption was compared with that of a commercial palladium catalyst with activated carbon as support. Although the palladium content of the magnetic support according to the invention was half of that of the commercial catalyst, the hydrogenation rate was equal.
- the starting material were spherical particles of aluminum oxide of dimensions between 1 and 0.85 mm.
- nickel oxide particles of a wide particle size distribution were provided in the spherical support bodies. Then the support particles thus loaded with nickel oxide were reduced in a flow of hydrogen at 450°C, yielding metallic nickel particles of particle dimensions varying from 3 to 50 nm.
- Figure 1 Encapsulated iron-nickel particle at a low magnification. Recording in the transmission electron microscope.
- Figure 2 Encapsulated iron-nickel particle at a very high magnification, (a) iron-nickel particle; (b) graphitic layers. Distance between the graphitic layers 0.33 nm
- Figure 3 Recording made with a scanning electron microscope equipped with a field emission electron gun, of a thick layer of carbon fibrils having a fishbone structure.
Abstract
Description
Claims
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EP99909404A EP1062672A2 (en) | 1998-03-09 | 1999-03-04 | Ferromagnetic particles |
JP2000536082A JP2002507055A (en) | 1998-03-09 | 1999-03-04 | Ferromagnetic particles |
AU28610/99A AU2861099A (en) | 1998-03-09 | 1999-03-04 | Ferromagnetic particles |
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WO2001039217A1 (en) * | 1999-11-25 | 2001-05-31 | Nanomagnetics Limited | Magnetic fluid |
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AU2861099A (en) | 1999-09-27 |
JP2002507055A (en) | 2002-03-05 |
ZA991800B (en) | 1999-10-04 |
WO1999046782A3 (en) | 1999-10-21 |
NL1008528C2 (en) | 1999-09-10 |
EP1062672A2 (en) | 2000-12-27 |
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