CN109665981B - Preparation method of caprolactam - Google Patents
Preparation method of caprolactam Download PDFInfo
- Publication number
- CN109665981B CN109665981B CN201710966138.0A CN201710966138A CN109665981B CN 109665981 B CN109665981 B CN 109665981B CN 201710966138 A CN201710966138 A CN 201710966138A CN 109665981 B CN109665981 B CN 109665981B
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- Prior art keywords
- caprolactam
- solvent
- crystallization
- product
- crude
- Prior art date
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- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical compound O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 title claims abstract description 684
- 238000002360 preparation method Methods 0.000 title claims abstract description 33
- 239000002904 solvent Substances 0.000 claims abstract description 137
- 238000002425 crystallisation Methods 0.000 claims abstract description 120
- 230000008025 crystallization Effects 0.000 claims abstract description 120
- 238000005984 hydrogenation reaction Methods 0.000 claims abstract description 107
- 239000000047 product Substances 0.000 claims abstract description 107
- 238000000034 method Methods 0.000 claims abstract description 80
- VEZUQRBDRNJBJY-UHFFFAOYSA-N cyclohexanone oxime Chemical compound ON=C1CCCCC1 VEZUQRBDRNJBJY-UHFFFAOYSA-N 0.000 claims abstract description 64
- 230000008569 process Effects 0.000 claims abstract description 41
- 238000006237 Beckmann rearrangement reaction Methods 0.000 claims abstract description 32
- 239000012043 crude product Substances 0.000 claims abstract description 27
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 claims description 139
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 66
- 239000003054 catalyst Substances 0.000 claims description 62
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 47
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 claims description 32
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 30
- 150000001335 aliphatic alkanes Chemical class 0.000 claims description 25
- 125000004432 carbon atom Chemical group C* 0.000 claims description 23
- 238000004821 distillation Methods 0.000 claims description 22
- 229910052763 palladium Inorganic materials 0.000 claims description 20
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 14
- PEQSKSXLTLCHTC-UHFFFAOYSA-N 1,3,4,5-tetrahydroazepin-2-one Chemical compound O=C1CCCC=CN1 PEQSKSXLTLCHTC-UHFFFAOYSA-N 0.000 claims description 12
- GXDHCNNESPLIKD-UHFFFAOYSA-N 2-methylhexane Natural products CCCCC(C)C GXDHCNNESPLIKD-UHFFFAOYSA-N 0.000 claims description 12
- 238000009835 boiling Methods 0.000 claims description 10
- 150000008282 halocarbons Chemical class 0.000 claims description 10
- VFWCMGCRMGJXDK-UHFFFAOYSA-N 1-chlorobutane Chemical compound CCCCCl VFWCMGCRMGJXDK-UHFFFAOYSA-N 0.000 claims description 9
- ZAFNJMIOTHYJRJ-UHFFFAOYSA-N Diisopropyl ether Chemical compound CC(C)OC(C)C ZAFNJMIOTHYJRJ-UHFFFAOYSA-N 0.000 claims description 9
- NHTMVDHEPJAVLT-UHFFFAOYSA-N Isooctane Chemical compound CC(C)CC(C)(C)C NHTMVDHEPJAVLT-UHFFFAOYSA-N 0.000 claims description 9
- JYYRTWNCBVRKMN-UHFFFAOYSA-N Octahydrophenazine Natural products C1CCCC2=C1N=C1CCCCC1=N2 JYYRTWNCBVRKMN-UHFFFAOYSA-N 0.000 claims description 9
- JVSWJIKNEAIKJW-UHFFFAOYSA-N dimethyl-hexane Natural products CCCCCC(C)C JVSWJIKNEAIKJW-UHFFFAOYSA-N 0.000 claims description 9
- 239000002808 molecular sieve Substances 0.000 claims description 9
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 9
- AFABGHUZZDYHJO-UHFFFAOYSA-N 2-Methylpentane Chemical compound CCCC(C)C AFABGHUZZDYHJO-UHFFFAOYSA-N 0.000 claims description 8
- ZUBZATZOEPUUQF-UHFFFAOYSA-N isononane Chemical compound CCCCCCC(C)C ZUBZATZOEPUUQF-UHFFFAOYSA-N 0.000 claims description 8
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 8
- BKIMMITUMNQMOS-UHFFFAOYSA-N nonane Chemical compound CCCCCCCCC BKIMMITUMNQMOS-UHFFFAOYSA-N 0.000 claims description 8
- FSHMPNBRNOGDDK-UHFFFAOYSA-N 1,2,3,4,4a,5,5a,6-octahydrophenazine Chemical compound C1=CCC2NC(CCCC3)C3=NC2=C1 FSHMPNBRNOGDDK-UHFFFAOYSA-N 0.000 claims description 7
- 239000007795 chemical reaction product Substances 0.000 claims description 7
- 229910052759 nickel Inorganic materials 0.000 claims description 7
- 229910001404 rare earth metal oxide Inorganic materials 0.000 claims description 7
- 229910052799 carbon Inorganic materials 0.000 claims description 6
- UAEPNZWRGJTJPN-UHFFFAOYSA-N methylcyclohexane Chemical compound CC1CCCCC1 UAEPNZWRGJTJPN-UHFFFAOYSA-N 0.000 claims description 6
- GDOPTJXRTPNYNR-UHFFFAOYSA-N methylcyclopentane Chemical compound CC1CCCC1 GDOPTJXRTPNYNR-UHFFFAOYSA-N 0.000 claims description 6
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 claims description 5
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 claims description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 4
- BZLVMXJERCGZMT-UHFFFAOYSA-N Methyl tert-butyl ether Chemical compound COC(C)(C)C BZLVMXJERCGZMT-UHFFFAOYSA-N 0.000 claims description 3
- 150000005826 halohydrocarbons Chemical class 0.000 claims description 3
- GYNNXHKOJHMOHS-UHFFFAOYSA-N methyl-cycloheptane Natural products CC1CCCCCC1 GYNNXHKOJHMOHS-UHFFFAOYSA-N 0.000 claims description 3
- 229910003445 palladium oxide Inorganic materials 0.000 claims description 3
- MPPPKRYCTPRNTB-UHFFFAOYSA-N 1-bromobutane Chemical compound CCCCBr MPPPKRYCTPRNTB-UHFFFAOYSA-N 0.000 claims description 2
- DURPTKYDGMDSBL-UHFFFAOYSA-N 1-butoxybutane Chemical compound CCCCOCCCC DURPTKYDGMDSBL-UHFFFAOYSA-N 0.000 claims description 2
- PZHIWRCQKBBTOW-UHFFFAOYSA-N 1-ethoxybutane Chemical compound CCCCOCC PZHIWRCQKBBTOW-UHFFFAOYSA-N 0.000 claims description 2
- UPSXAPQYNGXVBF-UHFFFAOYSA-N 2-bromobutane Chemical compound CCC(C)Br UPSXAPQYNGXVBF-UHFFFAOYSA-N 0.000 claims description 2
- BSPCSKHALVHRSR-UHFFFAOYSA-N 2-chlorobutane Chemical compound CCC(C)Cl BSPCSKHALVHRSR-UHFFFAOYSA-N 0.000 claims description 2
- 229910052684 Cerium Inorganic materials 0.000 claims description 2
- XOBKSJJDNFUZPF-UHFFFAOYSA-N Methoxyethane Chemical compound CCOC XOBKSJJDNFUZPF-UHFFFAOYSA-N 0.000 claims description 2
- QYKIQEUNHZKYBP-UHFFFAOYSA-N Vinyl ether Chemical compound C=COC=C QYKIQEUNHZKYBP-UHFFFAOYSA-N 0.000 claims description 2
- QQQCWVDPMPFUGF-ZDUSSCGKSA-N alpinetin Chemical compound C1([C@H]2OC=3C=C(O)C=C(C=3C(=O)C2)OC)=CC=CC=C1 QQQCWVDPMPFUGF-ZDUSSCGKSA-N 0.000 claims description 2
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 2
- QTBFPMKWQKYFLR-UHFFFAOYSA-N isobutyl chloride Chemical compound CC(C)CCl QTBFPMKWQKYFLR-UHFFFAOYSA-N 0.000 claims description 2
- ULYZAYCEDJDHCC-UHFFFAOYSA-N isopropyl chloride Chemical compound CC(C)Cl ULYZAYCEDJDHCC-UHFFFAOYSA-N 0.000 claims description 2
- 229910052746 lanthanum Inorganic materials 0.000 claims description 2
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 2
- SYSQUGFVNFXIIT-UHFFFAOYSA-N n-[4-(1,3-benzoxazol-2-yl)phenyl]-4-nitrobenzenesulfonamide Chemical class C1=CC([N+](=O)[O-])=CC=C1S(=O)(=O)NC1=CC=C(C=2OC3=CC=CC=C3N=2)C=C1 SYSQUGFVNFXIIT-UHFFFAOYSA-N 0.000 claims description 2
- SNMVRZFUUCLYTO-UHFFFAOYSA-N n-propyl chloride Chemical compound CCCCl SNMVRZFUUCLYTO-UHFFFAOYSA-N 0.000 claims description 2
- 229910052697 platinum Inorganic materials 0.000 claims description 2
- NBRKLOOSMBRFMH-UHFFFAOYSA-N tert-butyl chloride Chemical compound CC(C)(C)Cl NBRKLOOSMBRFMH-UHFFFAOYSA-N 0.000 claims description 2
- NUMQCACRALPSHD-UHFFFAOYSA-N tert-butyl ethyl ether Chemical compound CCOC(C)(C)C NUMQCACRALPSHD-UHFFFAOYSA-N 0.000 claims description 2
- 239000013078 crystal Substances 0.000 abstract description 74
- 238000004519 manufacturing process Methods 0.000 abstract description 9
- 239000012046 mixed solvent Substances 0.000 description 41
- 239000000243 solution Substances 0.000 description 36
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 35
- 238000005406 washing Methods 0.000 description 34
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 32
- 239000000203 mixture Substances 0.000 description 29
- 238000003756 stirring Methods 0.000 description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 28
- 238000001816 cooling Methods 0.000 description 26
- 239000012452 mother liquor Substances 0.000 description 25
- 238000006243 chemical reaction Methods 0.000 description 24
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 22
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 22
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 20
- 239000012535 impurity Substances 0.000 description 20
- 239000001257 hydrogen Substances 0.000 description 19
- 229910052739 hydrogen Inorganic materials 0.000 description 19
- 238000000926 separation method Methods 0.000 description 17
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 16
- 238000001704 evaporation Methods 0.000 description 15
- 239000002002 slurry Substances 0.000 description 15
- 238000005119 centrifugation Methods 0.000 description 14
- 239000007788 liquid Substances 0.000 description 14
- 239000000523 sample Substances 0.000 description 13
- 239000012071 phase Substances 0.000 description 12
- 238000004458 analytical method Methods 0.000 description 11
- 239000012808 vapor phase Substances 0.000 description 11
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 9
- 230000008020 evaporation Effects 0.000 description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 8
- 238000010521 absorption reaction Methods 0.000 description 8
- 150000001298 alcohols Chemical class 0.000 description 8
- 239000012286 potassium permanganate Substances 0.000 description 8
- 239000002244 precipitate Substances 0.000 description 8
- 239000012086 standard solution Substances 0.000 description 8
- 239000007864 aqueous solution Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000000746 purification Methods 0.000 description 7
- HNRMPXKDFBEGFZ-UHFFFAOYSA-N 2,2-dimethylbutane Chemical compound CCC(C)(C)C HNRMPXKDFBEGFZ-UHFFFAOYSA-N 0.000 description 6
- TVSPOLBJUVJVCV-UHFFFAOYSA-N benzene;heptane Chemical compound C1=CC=CC=C1.CCCCCCC TVSPOLBJUVJVCV-UHFFFAOYSA-N 0.000 description 6
- 230000008033 biological extinction Effects 0.000 description 6
- 239000012153 distilled water Substances 0.000 description 6
- 238000007670 refining Methods 0.000 description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 5
- 101100494773 Caenorhabditis elegans ctl-2 gene Proteins 0.000 description 5
- 101100112369 Fasciola hepatica Cat-1 gene Proteins 0.000 description 5
- 101100005271 Neurospora crassa (strain ATCC 24698 / 74-OR23-1A / CBS 708.71 / DSM 1257 / FGSC 987) cat-1 gene Proteins 0.000 description 5
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 5
- 239000006227 byproduct Substances 0.000 description 5
- 238000005265 energy consumption Methods 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- VLJXXKKOSFGPHI-UHFFFAOYSA-N 3-methylhexane Chemical compound CCCC(C)CC VLJXXKKOSFGPHI-UHFFFAOYSA-N 0.000 description 4
- 239000004215 Carbon black (E152) Substances 0.000 description 4
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 4
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 4
- 235000011130 ammonium sulphate Nutrition 0.000 description 4
- 239000012159 carrier gas Substances 0.000 description 4
- 238000001914 filtration Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- FDOMEEULKNYULF-UHFFFAOYSA-N heptane;methanol Chemical compound OC.CCCCCCC FDOMEEULKNYULF-UHFFFAOYSA-N 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 150000002430 hydrocarbons Chemical class 0.000 description 4
- 239000007791 liquid phase Substances 0.000 description 4
- 235000013162 Cocos nucifera Nutrition 0.000 description 3
- 244000060011 Cocos nucifera Species 0.000 description 3
- 239000004952 Polyamide Substances 0.000 description 3
- 239000002585 base Substances 0.000 description 3
- NLXVHTCVIKWWDK-UHFFFAOYSA-N benzene;1-chlorobutane Chemical compound CCCCCl.C1=CC=CC=C1 NLXVHTCVIKWWDK-UHFFFAOYSA-N 0.000 description 3
- VBEKGXAPCZTFJW-UHFFFAOYSA-N benzene;octane Chemical compound C1=CC=CC=C1.CCCCCCCC VBEKGXAPCZTFJW-UHFFFAOYSA-N 0.000 description 3
- -1 bromoisopropyl Chemical group 0.000 description 3
- 239000012018 catalyst precursor Substances 0.000 description 3
- 230000018044 dehydration Effects 0.000 description 3
- 238000006297 dehydration reaction Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 150000002170 ethers Chemical class 0.000 description 3
- KWHDXJHBFYQOTK-UHFFFAOYSA-N heptane;toluene Chemical compound CCCCCCC.CC1=CC=CC=C1 KWHDXJHBFYQOTK-UHFFFAOYSA-N 0.000 description 3
- 150000002431 hydrogen Chemical class 0.000 description 3
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- QIMIPFTUUACSIT-UHFFFAOYSA-N methanol;2,2,4-trimethylpentane Chemical compound OC.CC(C)CC(C)(C)C QIMIPFTUUACSIT-UHFFFAOYSA-N 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 229920002647 polyamide Polymers 0.000 description 3
- 229910052761 rare earth metal Inorganic materials 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000002791 soaking Methods 0.000 description 3
- 229920002994 synthetic fiber Polymers 0.000 description 3
- 239000012209 synthetic fiber Substances 0.000 description 3
- 229920003002 synthetic resin Polymers 0.000 description 3
- 239000000057 synthetic resin Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- XCXDCBTVTRUYNF-UHFFFAOYSA-N methanol;octane Chemical compound OC.CCCCCCCC XCXDCBTVTRUYNF-UHFFFAOYSA-N 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- DGDYEWHHLLKNRD-UHFFFAOYSA-N 1,2,3,4-tetrahydroazepin-7-one Chemical compound O=C1NCCCC=C1 DGDYEWHHLLKNRD-UHFFFAOYSA-N 0.000 description 1
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 1
- 229910002492 Ce(NO3)3·6H2O Inorganic materials 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 238000006683 Mannich reaction Methods 0.000 description 1
- 229920002292 Nylon 6 Polymers 0.000 description 1
- 229910002676 Pd(NO3)2·2H2O Inorganic materials 0.000 description 1
- 238000002835 absorbance Methods 0.000 description 1
- 238000006136 alcoholysis reaction Methods 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 1
- 229910052794 bromium Inorganic materials 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000007810 chemical reaction solvent Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 150000001924 cycloalkanes Chemical class 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 239000012458 free base Substances 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 229960000907 methylthioninium chloride Drugs 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000012264 purified product Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000006462 rearrangement reaction Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000002390 rotary evaporation Methods 0.000 description 1
- 239000012488 sample solution Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000012047 saturated solution Substances 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000011973 solid acid Substances 0.000 description 1
- 239000012265 solid product Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- HIFJUMGIHIZEPX-UHFFFAOYSA-N sulfuric acid;sulfur trioxide Chemical compound O=S(=O)=O.OS(O)(=O)=O HIFJUMGIHIZEPX-UHFFFAOYSA-N 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D201/00—Preparation, separation, purification or stabilisation of unsubstituted lactams
- C07D201/16—Separation or purification
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D223/00—Heterocyclic compounds containing seven-membered rings having one nitrogen atom as the only ring hetero atom
- C07D223/02—Heterocyclic compounds containing seven-membered rings having one nitrogen atom as the only ring hetero atom not condensed with other rings
- C07D223/06—Heterocyclic compounds containing seven-membered rings having one nitrogen atom as the only ring hetero atom not condensed with other rings with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D223/08—Oxygen atoms
- C07D223/10—Oxygen atoms attached in position 2
-
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Abstract
The invention relates to the field of caprolactam production, and discloses a preparation method of caprolactam, which comprises the following steps: the method comprises the steps of carrying out gas-phase Beckmann rearrangement reaction on cyclohexanone oxime to obtain a caprolactam crude product, and crystallizing the caprolactam crude product, wherein a solvent used for crystallization contains a solvent A and a solvent B, the solubility of caprolactam in the solvent A is more than 25 wt% at 20 ℃, the solubility of caprolactam in the solvent B is less than 5wt%, and the mass ratio of the solvent A to the solvent B is 1: (3-50) the process further comprising subjecting the crude caprolactam product to a first hydrogenation reaction prior to crystallization and/or subjecting the caprolactam crystals obtained from crystallization to a second hydrogenation reaction after crystallization. The method provided by the invention ensures that the caprolactam has higher yield under the premise of ensuring the high quality of the caprolactam.
Description
Technical Field
The invention relates to the field of caprolactam production, in particular to a preparation method of caprolactam.
Background
Caprolactam is one of the important raw materials of synthetic fibers and synthetic resins, and is mainly used for manufacturing polyamide fibers (nylon 6), resins, films and the like. At present, the industrial production of caprolactam mainly comprises a cyclohexane oxidation method, a benzene partial hydrogenation method, a photonitrosation method and the like, wherein 90% of the production processes are subjected to the Beckmann rearrangement of cyclohexanone oxime. The preparation of caprolactam from cyclohexanone oxime mainly adopts a liquid-phase Beckmann rearrangement process, while Japanese Sumitomo adopts a new vapor-phase Beckmann rearrangement process of cyclohexanone oxime.
The liquid-phase Beckmann rearrangement is that Beckmann rearrangement reaction is carried out under the catalysis of fuming sulfuric acid, and then the Beckmann rearrangement reaction is further neutralized with ammonia to obtain caprolactam and ammonium sulfate. The process has longer industrialization time, mature technology and stable product quality, and is the most widely used caprolactam production process in the world at present. However, the process has the defects of equipment corrosion, environmental pollution, unsatisfactory economic benefit and the like, and produces a large amount of ammonium sulfate as a byproduct.
The cyclohexanone oxime gas-phase Beckmann rearrangement reaction on the solid acid catalyst is a new technology for realizing the non-ammonium sulfate and green treatment of caprolactam, has the problems of no equipment corrosion, no environmental pollution and the like, and greatly simplifies the separation and purification of products, so that the new technology for the non-ammonium sulfate and green treatment of the gas-phase Beckmann rearrangement reaction is greatly focused by the industry personnel. The vapor phase Beckmann rearrangement reaction has the advantages that the reaction temperature is high, the thermal stability of cyclohexanone oxime and caprolactam is poor, the reaction solvent methanol is relatively active, various side reactions of cracking, hydrolysis, alcoholysis, hydrogenation, dehydrogenation, oxidation, thermal condensation and Mannich reaction are often accompanied, various byproducts are generated, forty kinds of byproducts are obtained in total, more than dozens of byproducts are not obtained, and the selectivity of the vapor phase rearrangement reaction is only about 96.5%. The crude caprolactam obtained after distillation, typically having a purity of about 98-99.6%, contains about 0.4-2% of other impurities.
Caprolactam is known as a raw material for the preparation of polyamides, and has high quality requirements for caprolactam products for the preparation of polyamides and further for the production of synthetic fibers and synthetic resins, and impurities of the order of μg/g affect the subsequent polymerization of caprolactam, are not liable to form filaments, are liable to cause oxidation or to cause changes in chromaticity. Therefore, various separation and purification methods are adopted to obtain crude caprolactam products, and various refining methods are adopted to finally obtain high-purity caprolactam, so that the high-purity caprolactam can be used for manufacturing products such as synthetic fibers, synthetic resins, films and the like.
Separation and purification methods using extraction, distillation, ion exchange do not adequately remove impurities similar to the chemical properties of caprolactam or byproducts having boiling points close to that of caprolactam. In this case, the hydrogenation method is a very effective means. The absorption value of potassium permanganate in the product can be effectively improved through hydrogenation reaction. However, in the current purification process, common separation and purification methods such as distillation, rectification, extraction, ion exchange, adsorption, hydrogenation and other single means or multiple means are combined, so that the purity of the obtained product can not be ensured to meet the industrial requirement of caprolactam.
The preparation of high purity chemicals by crystallization is one of the oldest and effective separation methods, polymer grade caprolactam is a heat sensitive material, and low impurity content is required, and separation and purification by crystallization has attracted extensive attention from large caprolactam production companies. The processes related to crystallization, including water, organic solvent crystallization and solvent-free crystallization, have been developed successively in Bayer, switzerland INVENT, dutch DSM, japanese Sumitomo, etc., and the solvent-free crystallization products have small particles and serious scaling, which make it difficult to operate continuously in industry and prevent the development thereof.
The separation, purification and refining method of epsilon-caprolactam disclosed in CN 101070298A, CN 101070299A comprises the step of crystallizing epsilon-caprolactam in an ether solution or a halogenated hydrocarbon solution containing crude epsilon-caprolactam. Specifically, this patent application discloses distilling a methanol solution of crude caprolactam obtained through a vapor phase beckmann rearrangement reaction to remove methanol, low boiling impurities and high boiling impurities to obtain crude caprolactam; dissolving the crude caprolactam into ether or halogenated hydrocarbon to obtain a caprolactam crude product-ether or halogenated hydrocarbon mixed solution; cooling and crystallizing the mixed solution and performing centrifugal separation to obtain caprolactam crystals; washing the caprolactam crystal with ether or halohydrocarbon and centrifuging to obtain caprolactam; then, the obtained caprolactam is subjected to hydrogenation reaction, so that a caprolactam product with extinction value, volatile alkali value and potassium permanganate absorption value meeting the requirements of industrial products is obtained.
CN1263091a discloses a process for purifying caprolactam, which comprises the steps of: crystallizing caprolactam in a hydrocarbon solution comprising crude caprolactam and contacting the crystallized caprolactam with hydrogen in the presence of a hydrogenation catalyst. CN1332158a discloses a process for preparing caprolactam comprising the steps of: (i) Pouring molten crude caprolactam and a solvent into a vessel, the solvent comprising an aliphatic hydrocarbon and having a temperature lower than the temperature of the crude caprolactam, and mixing the caprolactam and the solvent to obtain a first slurry comprising crystallized caprolactam and (ii) subjecting the slurry to solid-liquid separation to obtain caprolactam and a first liquid phase.
Although the above-mentioned processes purify crude caprolactam to some extent, the processes provided by the prior art do not combine high yields and high quality of caprolactam.
Disclosure of Invention
The invention aims to overcome the defect that the caprolactam preparation process provided by the prior art cannot have both high yield and high quality of caprolactam, and provides a caprolactam preparation method.
In order to achieve the above object, the present invention provides a process for producing caprolactam, which comprises: the method comprises the steps of carrying out gas-phase Beckmann rearrangement reaction on cyclohexanone oxime to obtain a caprolactam crude product, and crystallizing the caprolactam crude product, wherein a solvent used for crystallization contains a solvent A and a solvent B, the solubility of caprolactam in the solvent A is more than 25 wt% at 20 ℃, the solubility of caprolactam in the solvent B is less than 5wt%, and the mass ratio of the solvent A to the solvent B is 1: (1-50);
the process further comprises subjecting the crude caprolactam product to a first hydrogenation reaction prior to crystallization, and/or
After crystallization, the caprolactam crystals obtained from the crystallization are subjected to a second hydrogenation reaction.
The crystallization according to the invention can be explained by: the crude caprolactam product obtained by the vapor phase Beckmann rearrangement reaction of cyclohexanone oxime is dissolved in a hot solvent to be saturated, and soluble impurities are unsaturated, and when the product is cooled, the impurities are separated out due to supersaturation, and the unsaturated impurities are still remained in the solvent, so that purified product crystals can be obtained. If the content of soluble impurities is large, repeated crystallization is needed until the purity requirement is met. According to the crystallization principle, it is very important to select proper solvents, different crystallization solvents are adopted, the impurity removal capability is different, the obtained product yields are also greatly different, and the proper solvents are selected to have great influence on the product quality and yield of the target product. The solvent with small solubility of the target in the crystallization solvent is usually selected to ensure the final yield of the target product, for example, the solubility of caprolactam in water, alcohol and aromatic hydrocarbon is large, the product yield cannot be ensured, and the solvent is further excluded from the selection range of the crystallization solvent.
In the course of the studies, the inventors of the present invention found that the use of a solvent having a high solubility (25 wt% or more, preferably 40 wt% or more) for caprolactam in combination with a solvent having a low solubility (5 wt% or less, preferably 3 wt% or less) for caprolactam can provide a high yield of caprolactam while ensuring a high purity of caprolactam. The solvent with high solubility to caprolactam is more favorable for removing impurities in a crude product of caprolactam, and the solvent with low solubility to caprolactam is more favorable for improving the yield of caprolactam, and the solvent are matched in a certain mass ratio for use, so that the caprolactam has higher yield on the premise of ensuring the high purity of the caprolactam. In addition, the preparation method of caprolactam provided by the invention can be used for carrying out hydrogenation reaction before crystallization or after crystallization, in the preferred case, when the crude caprolactam product is firstly hydrogenated and then crystallized, the preferred hydrogenation reaction (first hydrogenation reaction) is carried out in the presence of at least one of aromatic hydrocarbon, alcohol and alkane with 6-12 carbon atoms, and at least one of aromatic hydrocarbon, alcohol and alkane with 6-12 carbon atoms after hydrogenation reaction can be used as a solvent in the crystallization process, so that the yield and purity of caprolactam can be ensured, the solvent required by a hydrogenation system can be further effectively utilized, and further, at least one of aromatic hydrocarbon, alcohol and alkane with 6-12 carbon atoms is used for replacing water, so that the energy consumption is greatly reduced.
The caprolactam obtained by the method has high yield and high purity, and in addition, the absorption value (PM) of the caprolactam obtained by the method is more than 10000s, the extinction value (at the wavelength of 290 nm) of the caprolactam is 0.05 or less, the volatile alkali value is 0.3mmol/kg or less, the chromaticity value is 3 or less, the acidity is 0.1mmol/kg or less and the alkalinity is 0.05mmol/kg or less, so that the caprolactam completely meets the requirements of industrial products.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The invention provides a preparation method of caprolactam, which comprises the following steps: the method comprises the steps of carrying out gas-phase Beckmann rearrangement reaction on cyclohexanone oxime to obtain a caprolactam crude product, and crystallizing the caprolactam crude product, wherein a solvent used for crystallization contains a solvent A and a solvent B, the solubility of caprolactam in the solvent A is more than 25 wt% at 20 ℃, the solubility of caprolactam in the solvent B is less than 5 wt%, and the mass ratio of the solvent A to the solvent B is 1: (1-50);
the process further comprises subjecting the crude caprolactam product to a first hydrogenation reaction prior to crystallization, and/or
After crystallization, the caprolactam crystals obtained from the crystallization are subjected to a second hydrogenation reaction.
The equilibrium relationship between solids and solutions is generally expressed in terms of the solubility of the solids in the solvent. In the present invention, the solubility refers to the mass content of caprolactam in a solution, also called the solvency, when the solvent and caprolactam reach (physical) solid-liquid phase equilibrium at a specific temperature, i.e. a saturated solution is formed.
In the invention, the solvent A can ensure the removal of impurities, the solvent B can ensure the yield of caprolactam, and the solvent A and the solvent B which are not considered by a person skilled in the art in specific mass ratio are used together, so that a better refining effect is achieved.
In order to further preferably achieve the refining effect, it is preferable that the solubility of caprolactam in the solvent A is 40% by weight or more and the solubility of caprolactam in the solvent B is 3% by weight or less at 20 ℃.
In the present invention, both the solvent a and the solvent B capable of satisfying the above-mentioned requirements can be used in the present invention, and preferably, the solvent a is selected from at least one of aromatic hydrocarbon and/or alcohol; the solvent B is at least one selected from halogenated hydrocarbon, ether and alkane with 6-12 carbon atoms.
According to a preferred embodiment of the present invention, cyclohexanone oxime is subjected to a vapor phase beckmann rearrangement to obtain a crude caprolactam product, which is then crystallized using a solvent comprising a solvent a selected from at least one of aromatic hydrocarbons and/or alcohols and a solvent B selected from at least one of halogenated hydrocarbons, ethers and alkanes having 6 to 12 carbon atoms, preferably alkanes having 6 to 12 carbon atoms, the mass ratio of solvent a to solvent B being 1: (1-50);
the process further comprises subjecting the crude caprolactam product to a first hydrogenation reaction prior to crystallization, and/or
After crystallization, the caprolactam crystals obtained from the crystallization are subjected to a second hydrogenation reaction.
Since the solubility of caprolactam in alkanes is smaller than that in halogenated hydrocarbons and ethers, it is preferable that the solvent B is at least one of alkanes having 6 to 12 carbon atoms, and it is more preferable that the solvent B is at least one of alkanes having 6 to 9 carbon atoms, in order to further increase the yield of caprolactam.
In the present invention, aromatic hydrocarbons having a caprolactam solubility of 25% by weight or more at 20 ℃ can be used in the present invention, and preferably the aromatic hydrocarbon is benzene and/or toluene.
In the present invention, alcohols having a caprolactam solubility of 25% by weight or more at 20℃may be used in the present invention, and the alcohols may be monohydric alcohols or dihydric alcohols, and the present invention is not particularly limited thereto, and the alcohols are preferably at least one selected from alcohols having 1 to 4 carbon atoms, more preferably at least one selected from methanol, ethanol, ethylene glycol, n-propanol and isopropanol, and even more preferably methanol.
In the present invention, the halogenated hydrocarbon may be one or more of monohalogenated hydrocarbon, dihaloalkane, and trihalogenated hydrocarbon, wherein halogen in the halogenated hydrocarbon is preferably chlorine element and/or bromine element, and further preferably, the halogenated hydrocarbon is at least one of 1-chloropropane, 2-chloropropane, chloro-n-butane, 2-chlorobutane, chloroisobutane, chloro-t-butane, n-bromopropane, bromoisopropyl, 1-bromobutane, and 2-bromobutane.
In the present invention, the ether may be mono-and/or di-ether, and further preferably, the ether is at least one of methylethyl ether, diethyl ether, n-propyl ether, isopropyl ether, n-butyl ether, ethylbutyl ether, ethylene glycol dimethyl ether, vinyl ether, methyl tertiary butyl ether, and ethyl tertiary butyl ether.
In the present invention, the alkane may be a linear aliphatic hydrocarbon, a branched aliphatic hydrocarbon, or a cyclic aliphatic hydrocarbon, and the present invention is not particularly limited thereto.
According to the present invention, the alkane having 6 to 12 carbon atoms may be a linear aliphatic hydrocarbon having 6 to 12 carbon atoms, preferably at least one of n-hexane, n-heptane, n-octane and n-nonane; the alkane with the carbon number of 6-12 can be branched aliphatic hydrocarbon with the carbon number of 6-12, preferably at least one of methylhexane (including 3-methylhexane and 2-methylhexane), isohexane, neohexane, isoheptane, isooctane and isononane; the alkane having 6 to 12 carbon atoms may be a cycloaliphatic hydrocarbon having 6 to 12 carbon atoms, preferably at least one of cyclohexane, methylcyclopentane, and methylcyclohexane.
Preferably, the alkane having 6 to 12 carbon atoms has a boiling point of 60 to 180 ℃, and more preferably 90 to 130 ℃.
According to a preferred embodiment of the present invention, the solvent B contains at least one of n-hexane, n-heptane, n-octane, n-nonane, methylhexane (including 3-methylhexane, 2-methylhexane), isohexane, neohexane, isoheptane, isooctane, isononane, cyclohexane, methylcyclopentane, and methylcyclohexane.
According to a preferred embodiment of the present invention, the solvent B is at least one of n-heptane, n-octane and isooctane.
In the invention, the good refining effect is realized by the matched use of the solvent A and the solvent B, and the mass ratio of the solvent A to the solvent B is 1: (1-50) in order to further facilitate removal of impurities in caprolactam and improvement of caprolactam yield, preferably, the mass ratio of solvent A to solvent B is 1: (3-40).
In addition, the selection of specific mass ratio of solvent A to solvent B is more beneficial to optimizing crystallization effect for different solvent A systems. According to a preferred embodiment of the invention, solvent a is selected from at least one of the aromatic hydrocarbons, the mass ratio of solvent a to solvent B being 1: (3-9). According to another preferred embodiment of the invention, solvent a is selected from at least one of the alcohols, the mass ratio of solvent a to solvent B being 1: (15-40).
The amount of the solvent used in the present invention is selected in a wide range, and preferably the amount of the solvent used is 60 to 150 parts by weight, more preferably 80 to 120 parts by weight, relative to 100 parts by weight of the crude caprolactam product to be crystallized. The solvent dosage of the preferred embodiment of the invention can not only meet the refining requirement, but also further reduce the solvent dosage.
When the invention carries out a first hydrogenation reaction on the crude caprolactam product before crystallization and then carries out crystallization, the crude caprolactam product to be crystallized refers to a hydrogenated crude caprolactam product obtained after the first hydrogenation reaction, and when the invention carries out the first hydrogenation reaction on the crude caprolactam product before crystallization, the crude caprolactam product to be crystallized refers to a crude caprolactam product obtained by the cyclohexanone oxime gas-phase Beckmann rearrangement reaction.
The crystallization mode of the present invention is not particularly limited, and may be, for example, cooling crystallization, evaporation crystallization or vacuum adiabatic cooling crystallization. The crystallizer used in the crystallization is not limited, and can be a cooling crystallizer, an evaporation crystallizer or a vacuum crystallizer, and can comprise at least one of a forced external circulation type crystallizer, an Oslo type crystallizer, an FC type crystallizer, a DTB type crystallizer, a DP type crystallizer and a Messo turbulent flow crystallizer.
The conditions for the crystallization are not particularly limited in the present invention, and preferably the temperature of the solution or melt during the crystallization is not higher than the melting point of caprolactam (70 ℃), and is preferably between-10℃and the melting point of caprolactam, especially between 20℃and the melting point of caprolactam. Preferably, the temperature of the crystallization is 10-65 ℃, further preferably 15-50 ℃.
According to the method provided by the invention, the crystallization process can be carried out with or without seeding, and the invention is not limited to this. According to the method provided by the invention, although one or more times of crystallization can be performed, the method provided by the invention can achieve good effect by performing one crystallization operation, so that the method preferably adopts one crystallization.
The invention may also comprise a step of separating the solid product obtained after crystallization from the mother liquor, preferably by filtration and/or centrifugation.
The centrifugation may use a pusher centrifuge, which may be operated in one or more steps. Screen conveyor centrifuges or screw conveyor centrifuges (decanters) are likewise suitable for the invention. The filtration may be accomplished by suction filters (which may be operated batchwise or continuously, optionally equipped with agitators) or belt filters.
In the process provided by the invention, additional process steps may be provided during and/or after the solid-liquid separation to enhance the purity of the crystals or crystal cake, i.e. the solvent washing step.
In one embodiment, the process according to the present invention may further comprise washing the caprolactam crystals separated after crystallization to obtain a caprolactam product of higher purity.
The washing may be performed one or more times, and the present invention is not particularly limited as to the choice of the washing solvent, and may be at least one of linear alkanes, cycloalkanes, ethers, and halohydrocarbons having a boiling range of less than 150 c, such as n-hexane, n-heptane, n-octane, n-nonane, methylhexane, isohexane, neohexane, isoheptane, isooctane, isononane, cyclohexane, isopropyl ether, methyl t-butyl ether, diethyl ether, chloro-n-butane, etc.
The source of the crude caprolactam product is not particularly limited in the present invention, as long as the crude caprolactam product obtained from the vapor phase Beckmann rearrangement of cyclohexanone oxime can be used in the present invention. In this case, the caprolactam crude product may generally contain caprolactam, cyclohexanone oxime, octahydrophenazine and isomers of tetrahydroazepin-2-one and/or tetrahydroazepin-2-one, and the content of caprolactam may be 98 to 99.6% by weight, the content of cyclohexanone oxime may be 0.01 to 0.5% by weight, the content of octahydrophenazine may be 0.01 to 0.3% by weight, and the total content of isomers of tetrahydroazepin-2-one and tetrahydroazepin-2-one may be 0.01 to 0.3% by weight, based on the total weight of the caprolactam crude product. The octahydrophenazine may be, for example, 1,2,3,4,6,7,8, 9-octahydrophenazine and the tetrahydroazepin-2-one may be, for example, at least one of 1,5,6, 7-tetrahydroazepin-2-one and structural isomers thereof. The sum of the amounts of caprolactam and impurities in the crude caprolactam product according to the invention is 100%, some of which are undefined.
According to a preferred embodiment of the invention, the gas phase Beckmann rearrangement reaction is carried out in the presence of a molecular sieve catalyst of MFI structure and the crude caprolactam product is obtained by distillation of the reaction product.
According to the preparation method of caprolactam, the vapor phase Beckmann rearrangement reaction comprises the step of reacting vapor phase cyclohexanone oxime in the presence of a molecular sieve catalyst with an MFI structure in the presence of carrier gas and a solvent. The conditions of the gas phase beckmann rearrangement reaction preferably include: the temperature is 320-450 ℃, more preferably 370-400 ℃; the pressure is 0.05-0.5MPa, more preferably 0.1-0.3MPa; the weight hourly space velocity of cyclohexanone oxime is 0.1-5h -1. The solvent may be a lower alcohol, for example, methanol, ethanol, or the like. The carrier gas may be various gases that do not react with the cyclohexanone oxime and the solvent under the conditions of the vapor phase Beckmann rearrangement reaction, and may be, for example, nitrogen gas and an inert gas. Both the pressure and the partial pressure refer to absolute pressure.
According to the preparation method of caprolactam provided by the invention, preferably, the molecular sieve catalyst with the MFI structure is a silicon-aluminum molecular sieve catalyst with the silicon-aluminum molar ratio of more than 5000, more preferably more than 10000, and the molecular sieve catalyst with the MFI structure is commercially available, for example, can be purchased from China petrochemical catalyst Chang Ling division; the catalyst can also be prepared by a conventional method, and the specific preparation method of the molecular sieve catalyst with the MFI structure can be referred to as a method disclosed in CN 1600428A.
The preparation method of the caprolactam provided by the invention further comprises the step of distilling the reaction product obtained after the gas-phase Beckmann rearrangement reaction mainly for removing the solvent, water and the like from the reaction product. The methods of distillation are well known to those skilled in the art and are not described in detail herein.
According to the preparation method of the caprolactam, provided by the invention, the caprolactam crystal is subjected to hydrogenation reaction with hydrogen, so that on one hand, tetrahydroazepine-2-one and isomers thereof which are difficult to sufficiently remove in the crystallization process can be converted into caprolactam, and the purity of the finally prepared caprolactam is further improved; on the other hand, the potassium permanganate absorption value of the caprolactam product can be effectively improved.
In the present invention, the hydrogenation reaction may be performed before crystallization (the first hydrogenation reaction) or after crystallization (the second hydrogenation reaction), and the present invention is not particularly limited thereto, but in the prior art, the hydrogenation reaction is performed after crystallization. The inventors of the present invention have found that caprolactam can also be made to have a higher yield and purity when the hydrogenation reaction is carried out before crystallization, and in addition energy savings can be achieved.
In the present invention, "first" and "second" in the first hydrogenation reaction and the second hydrogenation reaction are merely for distinguishing hydrogenation reactions performed in different stages, and the conditions of the hydrogenation reactions are not limited.
In the present invention, the conditions of the first hydrogenation reaction and the second hydrogenation reaction may be the same or different, and for example, the first hydrogenation reaction and the second hydrogenation reaction are each independently performed in the presence of at least one of an aromatic hydrocarbon, an alcohol, and an alkane having 6 to 12 carbon atoms and water, and in the presence of a hydrogenation catalyst.
The hydrogenation catalyst of the present invention may be selected from a wide range of catalysts, for example, the hydrogenation catalyst may be at least one selected from a nickel-based catalyst, a palladium-based catalyst and a platinum-based catalyst.
However, in order to further improve the product quality and reduce the energy consumption, it is preferable that the first hydrogenation reaction is carried out in the presence of a palladium catalyst in the presence of at least one of an aromatic hydrocarbon, an alcohol, and an alkane having 6 to 12 carbon atoms. The hydrogenation reaction is carried out in the presence of at least one of aromatic hydrocarbon, alcohol and alkane with 6-12 carbon atoms, and the energy consumption is obviously reduced compared with the hydrogenation reaction carried out in the presence of water. And at least one of the hydrogenated aromatic hydrocarbon, alcohol and alkane with 6-12 carbon atoms can be used as a partial crystallization solvent for the subsequent crystallization step.
According to the present invention, preferably, the first hydrogenation reaction is carried out in the presence of aromatic hydrocarbons, more preferably in the presence of benzene and/or toluene. By adopting the preferred embodiment, the quality and the yield of the prepared product can be ensured, and the energy consumption can be further reduced.
When the first hydrogenation reaction is performed in the presence of aromatic hydrocarbon and/or alcohol, it is preferable that the aromatic hydrocarbon and/or alcohol after the hydrogenation reaction be used as the solvent a, then the solvent B be added thereto, and further crystallization be performed, and the amount of the solvent a may be controlled by adding or evaporating to remove the aromatic hydrocarbon and/or alcohol after the hydrogenation reaction. The preferred embodiment can further utilize the solvent of hydrogenation reaction as a crystallization solvent, and saves energy consumption on the premise of ensuring the effect.
The inventors of the present invention have found during the course of the research that the use of palladium based catalysts is more advantageous for further removal of impurities from caprolactam when the hydrogenation reaction is carried out before the crystallization process.
The palladium-based catalyst of the present invention is widely selected, and preferably, the palladium-based catalyst includes a carrier and palladium and rare earth oxide supported on the carrier. The carrier may be at least one of activated carbon, silica, titania and alumina, and the rare earth oxide may be an oxide of lanthanum and/or cerium. Preferably, the carrier is activated carbon. The content of palladium and rare earth oxide in the palladium-based catalyst of the present invention is selected in a wide range, and preferably the content of palladium is 0.1 to 5wt% and the content of rare earth oxide is 0.2 to 10 wt% based on the total amount of the palladium-based catalyst. Specifically, the palladium-based catalyst can be prepared, for example, by referring to CN102430406a.
According to a preferred embodiment of the present invention, the process for the preparation of caprolactam comprises: in the presence of a hydrogenation solvent (preferably at least one of aromatic hydrocarbon, alcohol and alkane with 6-12 carbon atoms), in the presence of a hydrogenation catalyst (preferably palladium catalyst), carrying out a first hydrogenation reaction on a crude caprolactam product obtained by the vapor phase Beckmann rearrangement reaction of cyclohexanone oxime, adding a solvent A and/or B into the first hydrogenation reaction product, and then crystallizing. It is further preferred that the process further comprises the step of evaporating the first hydrogenation reaction product. The evaporation is used for removing the hydrogenation solvent in the first hydrogenation reaction product, so that the use amount of the solvent A and the solvent B meets the crystallization requirement.
The amount of the hydrogenation solvent used in the present invention may be selected in a wide range, and one skilled in the art may appropriately select the hydrogenation solvent according to the kind of the hydrogenation solvent used. Preferably, the hydrogenation solvent is used in an amount of from 20 to 400 parts by weight, preferably from 40 to 80 parts by weight, based on 100 parts by weight of the hydrogenation solvent and the crude caprolactam product.
According to the invention, the hydrogenation reaction can also be carried out after crystallization. The following is a detailed description.
According to another preferred embodiment of the present invention, the process for the preparation of caprolactam comprises: crystallizing a crude caprolactam product obtained by the cyclohexanone oxime gas-phase Beckmann rearrangement reaction, and performing a second hydrogenation reaction on caprolactam crystals obtained by the crystallization.
In the present invention, the conditions for the second hydrogenation reaction may be appropriately selected from conventional hydrogenation reaction conditions, and the second hydrogenation reaction may be carried out in the presence of water or in the presence of at least one of aromatic hydrocarbon, alcohol and alkane having 6 to 12 carbon atoms and water. The second hydrogenation reaction may be performed in the presence of water and in the presence of a nickel-based catalyst, or may be performed in the presence of a palladium-based catalyst and at least one of an aromatic hydrocarbon, an alcohol, and an alkane having 6 to 12 carbon atoms and water. The present invention is not particularly limited thereto.
When the hydrogenation reaction may be carried out in the presence of water, the water may be used in an amount of 10 to 200 parts by weight, preferably 10 to 50 parts by weight, relative to 100 parts by weight of caprolactam crystals.
According to a preferred embodiment of the present invention, the nickel-based catalyst is an amorphous nickel catalyst, which may be referred to as CN 1272490a and CN 1272491a, for example.
According to the invention, in order to ensure that the finally prepared caprolactam product has a higher potassium permanganate absorption and purity and a smaller extinction value, preferably the first and second hydrogenation reaction conditions each independently comprise: the temperature is 50-150deg.C, more preferably 60-90deg.C; the pressure is 0.2 to 1.5MPa, more preferably 0.5 to 1MPa. The pressure refers to absolute pressure.
The hydrogenation reaction can be operated in batch mode or continuous mode. When the hydrogenation reaction is a batch operation, the hydrogenation reaction time may be 0.5 to 3 hours, more preferably 1 to 2 hours. When the hydrogenation reaction is a continuous operation (e.g., a fixed bed process), the mass space velocity of caprolactam may be in the range of 0.5 to 30h -1.
The form of the reactor for carrying out the hydrogenation reaction is not particularly limited, a magnetically stabilized bed reactor, a fixed bed reactor or a slurry bed reactor can be used, and a fixed bed reactor can be selected for the hydrogenation reaction of molten caprolactam or an aqueous caprolactam solution. The hydrogenation of caprolactam in the molten state, aqueous caprolactam or caprolactam in an organic solvent may be carried out in a fixed bed reactor.
In one embodiment, the process provided according to the present invention further comprises collecting the caprolactam product by evaporation and/or distillation under reduced pressure after crystallization or the second hydrogenation reaction, thereby obtaining a caprolactam product having a higher potassium permanganate absorption value, a lower volatile base value, and a extinction value.
The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.
The following test methods were used in the following examples to evaluate the parameters related to caprolactam crystals and caprolactam products prepared:
(1) Purity of caprolactam
The purity of caprolactam was measured by gas chromatography, 7890GC, a capillary column of Innowax m, and a minimum detection limit of 0.1. Mu.g/g.
(2) Potassium permanganate absorption (PM) of caprolactam
Pouring 3.000 g of caprolactam into a 100mL colorimetric tube, diluting to a scale with distilled water, shaking uniformly, placing into a constant-temperature water bath at 20.0 ℃, adding 1mL of potassium permanganate solution with the concentration of 0.01N into the colorimetric tube, shaking uniformly immediately, starting a stopwatch, and stopping the stopwatch when the color of the sample solution in the colorimetric tube is the same as that of a standard colorimetric solution (3.000 g of high-grade pure Co (NO 3)2·6H2 O and 12 mg of high-grade pure K 2Cr2O7 are dissolved in water and diluted to 1 liter and shaking uniformly), and recording the consumed time (calculated in seconds), namely the potassium permanganate absorption value.
(3) Volatile Base (VB)
In alkaline medium, the alkaline low molecular impurities in the sample are distilled out, absorbed by a known amount of hydrochloric acid solution, and excessive hydrochloric acid is dripped back by a sodium hydroxide standard solution. The number of moles of acid consumed per kg of sample was used as a measure of volatile base. The calculation formula is as follows:
VB(mmol/kg)＝[(V0-V)×CNaOH/M]×1000
Wherein: v 0 is the volume of NaOH standard solution consumed by the blank test, and the unit is mL;
v is the volume of NaOH standard solution consumed by the sample, and the unit is mL;
C NaOH is the accurate concentration of the NaOH standard solution, and the unit is mol/L;
M is the mass of the sample in g.
(4) Extinction value E (at 290nm wavelength)
In a 300mL Erlenmeyer flask, 50 g of the sample was weighed, 50mL of distilled water was added, and the sample was shaken well to dissolve completely and allowed to stand for 10 minutes. The extinction of a sample having a concentration of 50% by weight with respect to distilled water was measured using a spectrophotometer at a wavelength of 290 nm.
(5) Chromaticity value
In a 300mL Erlenmeyer flask, 50 g of the sample was weighed, 50mL of distilled water was added, and the sample was shaken well to dissolve completely and allowed to stand for 10 minutes. The absorbance of the sample at a concentration of 50% with respect to distilled water was measured at a wavelength of 390nm using a spectrophotometer.
(6) PH value
Caprolactam is dissolved in water, and the free acid or the free base in the sample is titrated by using hydrochloric acid or sodium hydroxide standard solution with methyl red-methylene blue as an indicator. The calculation formula is as follows:
Acidity (mmol/kg) = (v×c HCl)/m×1000
Basicity (mmol/kg) = (v×c NaOH)/m×1000
Wherein: v is the volume of standard solution consumed by the sample, and the unit is mL;
c HCl is the accurate concentration of the NaOH standard solution, and the unit is mol/L;
C NaOH is the accurate concentration of the NaOH standard solution, and the unit is mol/L;
M is the mass of the sample in g.
Example 1
This example is intended to illustrate the process for the preparation of caprolactam provided by the present invention.
(1) Preparation of caprolactam crude product: the cyclohexanone oxime gas phase Beckmann rearrangement reaction is carried out in an 80mL fixed bed reaction device, the inner diameter of the reactor is 28mm, the loading of a molecular sieve catalyst (purchased from China petrochemical catalyst Chang Ling division, trade name RBS-1) with an MFI structure is 9.45g, the reaction pressure is 0.1MPa, the reaction temperature of the catalyst bed is 380 ℃, the flow rate of nitrogen (carrier gas) is 3.0L/gcat/hr, the weight hourly space velocity of the cyclohexanone oxime is 1h -1, and the mass content of the cyclohexanone oxime in a methanol solution is 37.5%. And (3) circularly cooling and collecting a product obtained after the Beckmann rearrangement reaction by using an ethylene glycol solution at the temperature of minus 5 ℃ to obtain a mixture containing caprolactam, and then distilling the mixture to remove methanol, low-boiling impurities and high-boiling impurities to obtain a crude caprolactam product. The caprolactam crude product was analyzed and found to have the main composition: 99.36% by weight of caprolactam, 165. Mu.g/g of cyclohexanone oxime, 434. Mu.g/g of octahydrophenazine, 389. Mu.g/g of tetrahydroazepin-2-one.
(2) And (3) crystallization: 240g of the crude caprolactam product obtained by the method is taken and added into a 1L three-neck flask, 40g of benzene and 200g of n-heptane are added, the temperature is raised to 60-65 ℃, and stirring is carried out for 30 minutes (the speed is 150 r/min), so that the crude caprolactam product is completely dissolved in the mixed solvent. Continuing stirring (speed is 100 r/min) and cooling, and cooling to 25 ℃ to completely precipitate caprolactam crystals. The resulting slurry was centrifuged to obtain 218.1g of 99.9905 wt% caprolactam crystals and a mother liquor of crystallization of a benzene-n-heptane mixed solvent containing a small amount of caprolactam. Recovering the benzene-n-heptane mixed solvent from the crystallization mother liquor of the benzene-n-heptane mixed solvent. 200g of caprolactam crystals were returned to a 1L three-necked flask, 200g of n-heptane was added thereto, and the mixture was stirred and washed at room temperature for 10 minutes, followed by centrifugation to obtain 197g of 99.9926% by weight caprolactam crystals and an n-heptane washing solution. The n-heptane washing liquid is used as crystallization solvent.
(3) Hydrogenation reaction: 150g of caprolactam crystal (99.9926 wt%) is added into a500 mL reaction kettle, 150g of water is added, then 1.5g of amorphous nickel hydrogenation catalyst (industrial grade is SRNA-4, manufactured by China petrochemical catalyst Chang Ling division) is added, the temperature is heated to about 75 ℃, then hydrogen is introduced, the flow rate of the hydrogen is controlled at 100mL/min, the reaction pressure is maintained at 0.7MPa, and the aqueous solution of caprolactam crystal is contacted with the hydrogen for reaction for 1 hour. Then, dehydration was carried out by evaporation on a rotary evaporator (-0.09 MPa,80 ℃ C.), and distillation was carried out under reduced pressure under about 1mmHg to obtain 130g of caprolactam product, and then the distillation was stopped. The quality of the caprolactam product obtained by analysis is 99.9945%, the purity of the caprolactam is 35000s, the PM value is 0.040mmol/kg, the E value is 0.034, the chromaticity value is 0, and the acidity is 0.03mmol/kg.
Comparative example 1
The procedure of example 1 was followed, except that 40g of benzene was replaced with 40g of n-heptane during the crystallization in step (2), i.e., 240g of n-heptane was added as a crystallization solvent during the crystallization, specifically:
And (3) crystallization: 240g of the crude caprolactam product obtained in example 1 was taken and put into a 1L three-necked flask, 240g of n-heptane was further added, the mixture was heated to 60 to 65℃and stirred for 30 minutes (at a rate of 150 r/min) to completely dissolve the crude caprolactam product in the solvent. Continuing stirring (speed is 100 r/min) and cooling, and cooling to 25 ℃ to completely precipitate caprolactam crystals. The resulting slurry was centrifuged to obtain 221.8g of 99.9895 wt% caprolactam crystals and a mother liquor of crystallization in n-heptane solvent containing a small amount of caprolactam. Recovering the n-heptane solvent from the crystallization mother liquor containing the n-heptane solvent. 200g of caprolactam crystals were returned to a 1L three-necked flask, 200g of n-heptane was added thereto, and the mixture was stirred and washed at room temperature for 10 minutes, followed by centrifugation to obtain 197g of 99.9910% by weight caprolactam crystals and an n-heptane washing solution. The n-heptane washing liquid is used as crystallization solvent.
(3) The hydrogenation reaction was the same as described in example 1 to obtain caprolactam product. The caprolactam product quality obtained by analysis is 99.9923% of caprolactam purity, the PM value is 21600s, VB is 0.055mmol/kg, E value is 0.035, chromaticity value is 1, and acidity is 0.052mmol/kg.
Example 2
This example is intended to illustrate the process for the preparation of caprolactam provided by the present invention.
(1) A crude caprolactam product (99.36% by weight of caprolactam) was obtained in the same manner as in example 1.
(2) And (3) crystallization: 240g of the crude caprolactam product obtained by the method is taken and added into a 1L three-neck flask, 60g of benzene and 300g of n-octane are added, the temperature is raised to 65-70 ℃, and stirring is carried out for 30 minutes (the speed is 150 r/min), so that the crude caprolactam product is completely dissolved in the mixed solvent. Continuing stirring (speed is 100 r/min) and cooling, and cooling to 25 ℃ to completely precipitate caprolactam crystals. The resulting slurry was subjected to centrifugal separation to obtain 211.6g of 99.9917 wt% caprolactam crystals and a crystallization mother liquor of a benzene-n-octane mixed solvent containing a small amount of caprolactam. Recovering the benzene-n-octane mixed solvent from the crystallization mother liquor of the benzene-n-octane mixed solvent. 200g of caprolactam crystals were returned to a 1L three-necked flask, 200g of n-octane was added thereto, and the mixture was washed with stirring at room temperature for 10 minutes, followed by centrifugation to obtain 197g of 99.9936% by weight caprolactam crystals and an n-octane washing solution. The n-octane washing liquid is used as crystallization solvent for continuous use.
(3) Preparation of hydrogenation palladium catalyst:
Treatment of the activated carbon carrier: putting 104g of 4-10 mesh coconut shell type granular active carbon into a 500mL beaker, a) soaking and stirring for 30min with 300mL of water, washing and filtering, b) then soaking and stirring for 30min with 200mL of water, washing and filtering; repeating the above steps a) and b) once. Then 200mL of 0.5N nitric acid is used, and the mixture is soaked for 60min with gentle stirring, washed and filtered. Washing with distilled water to remove nitric acid until the pH is about 7, and drying at 100-105 ℃ for 6 hours to obtain 100g of treated coconut shell type granular active carbon for standby.
Preparing a palladium-rare earth aqueous solution: 2.56g of palladium nitrate Pd (NO 3)2·2H2 O (fw= 266.5) and 13 g of cerium nitrate Ce (NO 3)3·6H2 O (fw=434) were weighed into 120 g of water to obtain a palladium-rare earth aqueous solution.
Catalyst precursor: pouring palladium-rare earth aqueous solution into the treated coconut shell type granular active carbon, keeping the temperature at 50 ℃ and soaking for 6 hours (shaking for 30min once); then transferring the catalyst into a rotary evaporator, heating to 70 ℃, and removing water by rotary evaporation to obtain the catalyst precursor.
Reduction treatment: the catalyst precursor was dried in an oven at 100℃for 10h and then calcined at 200℃for 4h. Before use, the catalyst is reduced with H 2 at 80-100 ℃ for 2H under normal pressure, and the flow rate of H 2 is 4mL/min per gram of catalyst. The catalyst Cat-1 was obtained, wherein the content of Pd was 1% by weight and the content of CeO 2 was 5% by weight.
(4) Hydrogenation reaction: 150g of caprolactam crystal (99.9936 wt%) is added into a 500mL reaction kettle, 150g of n-octane is added, then 1.5g of catalyst Cat-1 with 40-80 meshes is added, the mixture is heated to about 75 ℃, then hydrogen is introduced, the flow rate of the hydrogen is controlled at 100mL/min, the reaction pressure is maintained at 0.7MPa, and the aqueous solution of the caprolactam crystal is contacted with the hydrogen for reaction for 1 hour. Then n-octane (-0.09 MPa,100 ℃) is removed by evaporation on a rotary evaporator, and then distillation is carried out under reduced pressure under the condition of about 1mmHg, 130g of caprolactam product is obtained, and distillation is stopped. The quality of the caprolactam product obtained by analysis is 99.9952%, the purity of the caprolactam is 39600s, the PM value is 0.029mmol/kg, the E value is 0.030, the chromaticity value is 0, and the acidity is 0.026mmol/kg.
Example 3
This example is intended to illustrate the process for the preparation of caprolactam provided by the present invention.
(1) A crude caprolactam product (99.36% by weight of caprolactam) was obtained in the same manner as in example 1.
(2) And (3) crystallization: 240g of the crude caprolactam product obtained by the method is taken and added into a 1L three-neck flask, 15g of methanol and 225g of n-heptane are added, the temperature is raised to 60-65 ℃, and stirring is carried out for 30 minutes (the speed is 150 r/min), so that the crude caprolactam product is completely dissolved in the mixed solvent. Continuing stirring (speed is 100 r/min) and cooling, and cooling to 25 ℃ to completely precipitate caprolactam crystals. The resulting slurry was subjected to centrifugal separation to obtain 213.5g of 99.9910 wt% caprolactam crystals and a crystallization mother liquor of a mixed solvent of methanol and n-heptane containing a small amount of caprolactam. Recovering the methanol-n-heptane mixed solvent from the crystallization mother liquor of the methanol-n-heptane mixed solvent. 200g of caprolactam crystals were returned to a 1L three-necked flask, 200g of n-heptane was added thereto, and the mixture was stirred and washed at room temperature for 10 minutes, followed by centrifugation to obtain 197g of 99.9922% by weight caprolactam crystals and an n-heptane washing solution. The n-heptane washing liquid is used as crystallization solvent.
(3) Hydrogenation reaction: 150g of caprolactam crystal (99.9922 wt%) is added into a500 mL reaction kettle, 150g of water is added, then 1.5g of amorphous nickel hydrogenation catalyst (industrial grade is SRNA-4, manufactured by China petrochemical catalyst Chang Ling division) is added, the temperature is heated to about 75 ℃, then hydrogen is introduced, the flow rate of the hydrogen is controlled at 100mL/min, the reaction pressure is maintained at 0.7MPa, and the aqueous solution of caprolactam crystal is contacted with the hydrogen for reaction for 1 hour. Then, dehydration was carried out by evaporation on a rotary evaporator (-0.09 MPa,80 ℃ C.), and distillation was carried out under reduced pressure under about 1mmHg to obtain 130g of caprolactam product, and then the distillation was stopped. The caprolactam product quality obtained by analysis, the purity of caprolactam is 99.9941%, the PM value is 33600s, the VB value is 0.038mmol/kg, the E value is 0.035, the chromaticity value is 0, and the acidity is 0.03mmol/kg.
Example 4
This example is intended to illustrate the process for the preparation of caprolactam provided by the present invention.
(1) A crude caprolactam product (99.36% by weight of caprolactam) was obtained in the same manner as in example 1.
(2) And (3) crystallization: 240g of the crude caprolactam product obtained by the method is taken and added into a 1L three-neck flask, 20g of methanol and 220g of isooctane are added, the temperature is increased to 60-65 ℃, and stirring is carried out for 30 minutes (the speed is 150 r/min), so that the crude caprolactam product is completely dissolved in the mixed solvent. Continuing stirring (speed is 100 r/min) and cooling, and cooling to 25 ℃ to completely precipitate caprolactam crystals. The resulting slurry was subjected to centrifugal separation to obtain 210.7g of 99.9917 wt% caprolactam crystals and a mother liquor of crystallization of a methanol-isooctane mixed solvent containing a small amount of caprolactam. Recovering the methanol-isooctane mixed solvent from the crystallization mother liquor of the methanol-isooctane mixed solvent. 200g of caprolactam crystals were returned to a 1L three-necked flask, 200g of isooctane was added thereto, and the mixture was washed at room temperature with stirring for 10 minutes, followed by centrifugation to obtain 197g of 99.9930% by weight caprolactam crystals and an isooctane washing solution. The isooctane washing liquid is used as crystallization solvent for continuous use.
(3) Hydrogenation reaction: 150g of caprolactam crystal (99.9930 wt%) is added into a 500mL reaction kettle, 150g of water is added, then 1.5g of amorphous nickel hydrogenation catalyst (industrial grade is SRNA-4, manufactured by China petrochemical catalyst Chang Ling division) is added, the temperature is heated to about 75 ℃, then hydrogen is introduced, the flow rate of the hydrogen is controlled at 100mL/min, the reaction pressure is maintained at 0.7MPa, and the aqueous solution of caprolactam crystal is contacted with the hydrogen for reaction for 1 hour. Then, dehydration was carried out by evaporation on a rotary evaporator (-0.09 MPa,80 ℃ C.), and distillation was carried out under reduced pressure under about 1mmHg to obtain 130g of caprolactam product, and then the distillation was stopped. The quality of the caprolactam product obtained by analysis is 99.9955%, the purity of the caprolactam is 39600s, the PM value is 0.028mmol/kg, the E value is 0.030, the chromaticity value is 0, and the acidity is 0.025mmol/kg.
Example 5
This example is intended to illustrate the process for the preparation of caprolactam provided by the present invention.
(1) A crude caprolactam product (99.36% by weight of caprolactam) was obtained in the same manner as in example 1.
(2) The palladium catalyst for hydrogenation was prepared as in step (3) of example 2.
(3) Hydrogenation reaction: dissolving the caprolactam crude product obtained in the step (1) in toluene solvent to obtain solution with toluene content of 80 wt%, taking 2.5kg of the solution, adding the solution into a 5L reaction kettle, adding 3g of catalyst Cat-1 with 40-80 meshes, heating to about 80 ℃, then introducing hydrogen, controlling the flow rate of the hydrogen at 100mL/min, maintaining the reaction pressure at 1MPa, and reacting for 1 hour.
(4) And (3) crystallization: evaporating the hydrogenation product obtained in the step (3) under normal pressure to remove a large amount of toluene, thereby obtaining a mixture with 15 weight percent of toluene. 300g of the mixture is taken and added into a 1L three-neck flask, 340g of n-heptane is added, the temperature is heated to 60-65 ℃, and the mixture is stirred for 30 minutes (the speed is 150 r/min), so that the hydrogenated caprolactam crude product is completely dissolved in the mixed solvent, and the mixture is cooled while continuing stirring (the speed is 100 r/min), the temperature is reduced to 30 ℃, and caprolactam crystals are completely separated out. The resulting slurry was centrifuged to obtain 218.3g of 99.9915 wt% caprolactam crystals and a mother liquor of crystallization of toluene-n-heptane mixed solvent containing a small amount of caprolactam. Recovering the toluene-n-heptane mixed solvent from the crystallization mother liquor of the toluene-n-heptane mixed solvent. 200g of caprolactam crystals were returned to a 1L three-necked flask, 200g of n-heptane was added thereto, and the mixture was stirred and washed at room temperature for 10 minutes, followed by centrifugation to obtain 197g of 99.9924% by weight caprolactam crystals and an n-heptane washing solution. The n-heptane washing liquid is used as crystallization solvent. The caprolactam crystals obtained were distilled under reduced pressure at about 1mmHg to obtain 140g of caprolactam product, and the distillation was stopped. The caprolactam product quality obtained by analysis is 99.9947% in purity, 34000s in PM value, 0.046mmol/kg in VB, 0.033 in E value, 0 in chromaticity value and 0.016mmol/kg in acidity.
Comparative example 2
The procedure of example 5 was followed, except that in the crystallization of step (4), the hydrogenation product obtained in step (3) was subjected to evaporation at normal pressure to completely remove toluene, specifically:
Steps (1) - (3) are the same as in example 5;
(4) And (3) crystallization: evaporating the hydrogenated product obtained in the step (3) under normal pressure to remove toluene to obtain a hydrogenated caprolactam crude product, adding 255g of the hydrogenated caprolactam crude product into a 1L three-neck flask, adding 385g of n-heptane, heating to 60-65 ℃, stirring for 30 minutes (the speed is 150 r/min), completely dissolving the hydrogenated caprolactam crude product into a mixed solvent, continuously stirring (the speed is 100 r/min) and cooling, and cooling to 30 ℃ to completely separate out caprolactam crystals. The resulting slurry was centrifuged to obtain 228.1g of 99.9911 wt% caprolactam crystals and a mother liquor of crystallization in n-heptane solvent containing a small amount of caprolactam. Recovering the n-heptane solvent from the crystallization mother liquor containing the n-heptane solvent. 200g of caprolactam crystals were returned to a 1L three-necked flask, 200g of n-heptane was added thereto, and the mixture was stirred and washed at room temperature for 10 minutes, followed by centrifugation to obtain 197g of 99.9921% by weight caprolactam crystals and an n-heptane washing solution. The n-heptane washing liquid is used as crystallization solvent. The caprolactam crystals obtained were distilled under reduced pressure at about 1mmHg to obtain 130g of caprolactam product, and the distillation was stopped. The quality of the caprolactam product obtained is analyzed, the purity of the caprolactam is 99.9933%, the PM value is 25200s, the VB value is 0.046mmol/kg, the E value is 0.037, the chromaticity value is 1, and the acidity is 0.020mmol/kg.
Example 6
This example is intended to illustrate the process for the preparation of caprolactam provided by the present invention.
(1) Preparation of caprolactam crude product: the cyclohexanone oxime gas phase Beckmann rearrangement reaction is carried out in an 80mL fixed bed reaction device, the inner diameter of the reactor is 28mm, the loading of a molecular sieve catalyst (purchased from China petrochemical catalyst Chang Ling division, trade name RBS-1) with an MFI structure is 9.45g, the pressure is 0.1MPa, the reaction temperature of the catalyst bed is 380 ℃, the flow rate of nitrogen (carrier gas) is 3.0L/gcat/hr, the weight hourly space velocity of the cyclohexanone oxime is 1h -1, and the mass content of the cyclohexanone oxime in a methanol solution is 37.5%. And (3) circularly cooling and collecting a product obtained after the Beckmann rearrangement reaction by using an ethylene glycol solution at the temperature of minus 5 ℃ to obtain a mixture containing caprolactam, and then distilling the mixture to remove methanol and low-boiling impurities to obtain a crude caprolactam product. The caprolactam crude product was analyzed and found to have the main composition: 98.17% by weight of caprolactam, 177. Mu.g/g of cyclohexanone oxime, 455. Mu.g/g of octahydrophenazine, 412. Mu.g/g of tetrahydroazepin-2-one.
(2) The palladium catalyst for hydrogenation was prepared as in step (3) of example 2.
(3) Hydrogenation reaction: dissolving the caprolactam crude product obtained in the step (1) in a benzene solvent to obtain a solution with the benzene content of 40 wt%, taking the solution as a hydrogenation raw material, carrying out hydrogenation reaction in an 80mL fixed bed reactor, wherein the inner diameter of the reactor is 28mm, 20g of catalyst Cat-1 is filled, the reaction temperature of the catalyst bed is 80 ℃, the hydrogen flow is 150mL/min, the WHSV of the caprolactam crude product is 4h -1, and the reaction pressure is 1MPa.
(4) And (3) crystallization: evaporating the hydrogenation product obtained in the step (3) under normal pressure to remove a large amount of benzene to obtain a mixture with the benzene content of 10 weight percent. 300g of the mixture is taken and added into a 1L three-neck flask, 270g of n-heptane is added, the temperature is heated to 60-65 ℃, and stirring is carried out for 30 minutes (the speed is 150 r/min), so that the hydrogenated caprolactam crude product is completely dissolved in a mixed solvent, cooling is carried out while stirring is continued (the speed is 100 r/min), the temperature is reduced to 20 ℃, and caprolactam crystals are completely separated out. The resulting slurry was subjected to centrifugal separation to obtain 222.3g of 99.9885 wt% caprolactam crystals and a crystallization mother liquor of a benzene-n-heptane mixed solvent containing a small amount of caprolactam. Recovering the benzene-n-heptane mixed solvent from the crystallization mother liquor of the benzene-n-heptane mixed solvent. 200g of caprolactam crystals were returned to a 1L three-necked flask, 200g of n-heptane was added thereto, and the mixture was stirred and washed at room temperature for 10 minutes, followed by centrifugation to obtain 197g of 99.9914% by weight caprolactam crystals and an n-heptane washing solution. The n-heptane washing liquid is used as crystallization solvent. The caprolactam crystals obtained were distilled under reduced pressure at about 1mmHg to obtain 140g of caprolactam product, and the distillation was stopped. The caprolactam product quality obtained by analysis, the purity of caprolactam is 99.9938%, the PM value is 31600s, the VB value is 0.042mmol/kg, the E value is 0.038, the chromaticity value is 0, and the acidity is 0.027mmol/kg.
Example 7
This example is intended to illustrate the process for the preparation of caprolactam provided by the present invention.
(1) A crude caprolactam product (99.36% by weight of caprolactam) was obtained in the same manner as in example 1.
(2) The palladium catalyst for hydrogenation was prepared as in step (3) of example 2.
(3) Hydrogenation reaction: dissolving the caprolactam crude product obtained in the step (1) in a methanol solvent to obtain a solution with 40 weight percent of methanol content, taking 2.5kg of the solution, adding the solution into a 5L reaction kettle, adding 15g of catalyst Cat-1, heating to about 80 ℃, then introducing hydrogen, controlling the flow rate of the hydrogen at 100mL/min, maintaining the reaction pressure at 1MPa, and reacting for 1 hour.
(4) And (3) crystallization: evaporating the hydrogenation product obtained in the step (3) under normal pressure to remove a large amount of methanol, thereby obtaining a mixture with the methanol content of 4 weight percent. 300g of the mixture is taken and added into a 1L three-neck flask, 300g of n-heptane is added, the temperature is heated to 60-65 ℃, and stirring is carried out for 30 minutes (the speed is 150 r/min), so that the hydrogenated caprolactam crude product is completely dissolved in a mixed solvent, cooling is carried out while stirring is continued (the speed is 100 r/min), the temperature is reduced to 20 ℃, and caprolactam crystals are completely separated out. The resulting slurry was subjected to centrifugal separation to obtain 254.5g of 99.9925 wt% caprolactam crystals and a crystallization mother liquor of a mixed solvent of methanol and n-heptane containing a small amount of caprolactam. Recovering the methanol-n-heptane mixed solvent from the crystallization mother liquor of the methanol-n-heptane mixed solvent. 200g of caprolactam crystals were returned to a 1L three-necked flask, 200g of n-heptane was added thereto, and the mixture was stirred and washed at room temperature for 10 minutes, followed by centrifugation to obtain 197g of 99.9936% by weight caprolactam crystals and an n-heptane washing solution. The n-heptane washing liquid is used as crystallization solvent. The caprolactam crystals obtained were distilled under reduced pressure at about 1mmHg to obtain 140g of caprolactam product, and the distillation was stopped. The quality of the caprolactam product obtained by analysis is 99.9947%, the purity of the caprolactam is 36000s, the PM value is 0.033mmol/kg, the E value is 0.030, the chromaticity value is 0, and the acidity is 0.03mmol/kg.
Example 8
This example is intended to illustrate the process for the preparation of caprolactam provided by the present invention.
The procedure of example 1 was followed, except that 200g of n-heptane used in the crystallization was replaced with an equivalent amount of n-chlorobutane and the corresponding washing solvent was also replaced with an equivalent amount of n-chlorobutane, in particular:
(1) A crude caprolactam product (99.36% by weight of caprolactam) was obtained in the same manner as in example 1.
(2) And (3) crystallization: 240g of the crude caprolactam product obtained by the method is taken and added into a 1L three-neck flask, 40g of benzene and 200g of n-butyl chloride are added, the temperature is raised to 60-65 ℃, and stirring is carried out for 30 minutes (the speed is 150 r/min), so that the crude caprolactam product is completely dissolved in the mixed solvent. Continuing stirring (speed is 100 r/min) and cooling, and cooling to 25 ℃ to completely precipitate caprolactam crystals. The resulting slurry was subjected to centrifugal separation to obtain 208.1g of 99.9914 wt% caprolactam crystals and a mother liquor of crystallization of a benzene-chloro-n-butane mixed solvent containing a small amount of caprolactam. Recovering the benzene-chloro-n-butane mixed solvent from the crystallization mother liquor of the benzene-chloro-n-butane mixed solvent. 200g of caprolactam crystals were returned to a 1L three-necked flask, 200g of n-chlorobutane was added thereto, and the mixture was stirred and washed at room temperature for 10 minutes, followed by centrifugation to obtain 194g of 99.9925% by weight caprolactam crystals and a washing solution of n-chlorobutane. The chloro-n-butane washing liquid is used as crystallization solvent for continuous use.
(3) The hydrogenation was the same as described in example 1 and distillation was stopped after 130g of caprolactam product was obtained. The caprolactam product quality obtained by analysis, the purity of caprolactam is 99.9942%, the PM value is 31600s, the VB value is 0.036mmol/kg, the E value is 0.025, the chromaticity value is 0, and the acidity is 0.025mmol/kg.
Example 9
This example is intended to illustrate the process for the preparation of caprolactam provided by the present invention.
The procedure of example 1 is followed, except that 200g of n-heptane used in the crystallization is replaced by an equivalent amount of isopropyl ether and the corresponding washing solvent is replaced by an equivalent amount of isopropyl ether, in particular:
(1) A crude caprolactam product (99.36% by weight of caprolactam) was obtained in the same manner as in example 1.
(2) And (3) crystallization: 240g of the crude caprolactam product obtained by the method is taken and added into a 1L three-neck flask, 20g of benzene and 220g of isopropyl ether are added, the temperature is raised to 60-65 ℃, and stirring is carried out for 30 minutes (the speed is 150 r/min), so that the crude caprolactam product is completely dissolved in the mixed solvent. Continuing stirring (speed is 100 r/min) and cooling, and cooling to 25 ℃ to completely precipitate caprolactam crystals. The resulting slurry was centrifuged to obtain 198.2g of 99.9919 wt% caprolactam crystals and a mother liquor of crystallization of a benzene-isopropyl ether mixed solvent containing a small amount of caprolactam. Recovering the benzene-isopropyl ether mixed solvent from the crystallization mother liquor of the benzene-isopropyl ether mixed solvent. 180g of caprolactam crystals were returned to a 1L three-necked flask, 180g of isopropyl ether was added thereto, and the mixture was washed with stirring at room temperature for 10 minutes, followed by centrifugation to obtain 177g of 99.9933% by weight caprolactam crystals and isopropyl ether washing liquid. The isopropyl ether washing solution is used as a crystallization solvent for continuous use.
(3) The hydrogenation was the same as described in example 1 and distillation was stopped after 140g of caprolactam product was obtained. The caprolactam product quality obtained by analysis, the purity 99.9944% of caprolactam, the PM value of 39600s, VB of 0.033mmol/kg, E value of 0.025, chromaticity value of 0 and acidity of 0.020mmol/kg.
Example 10
This example is intended to illustrate the process for the preparation of caprolactam provided by the present invention.
(1) A crude caprolactam product (99.36% by weight of caprolactam) was obtained in the same manner as in example 1.
(2) And (3) crystallization: 240g of the crude caprolactam product obtained by the method is taken and added into a 1L three-neck flask, 10g of methanol and 230g of n-octane are added, the temperature is increased to 60-65 ℃, and stirring is carried out for 30 minutes (the speed is 150 r/min), so that the crude caprolactam product is completely dissolved in the mixed solvent. Continuing stirring (speed is 100 r/min) and cooling, and cooling to 25 ℃ to completely precipitate caprolactam crystals. The resulting slurry was subjected to centrifugal separation to obtain 194.5g of 99.9920 wt% caprolactam crystals and a crystallization mother liquor of a mixed solvent of methanol and n-octane containing a small amount of caprolactam. Recovering the methanol-n-octane mixed solvent from the crystallization mother liquor of the methanol-n-octane mixed solvent. 200g of caprolactam crystals were returned to a 1L three-necked flask, 200g of n-octane was added thereto, and the mixture was washed with stirring at room temperature for 10 minutes, followed by centrifugation to obtain 197g of 99.9935% by weight caprolactam crystals and an n-octane washing solution. The n-octane washing liquid is used as crystallization solvent for continuous use.
(3) The hydrogenation was carried out as described in example 3. Distillation was stopped after 140g of caprolactam product was obtained. The caprolactam product quality obtained by analysis is 99.9948%, the purity of caprolactam is 36000s, the PM value is 0.035mmol/kg, the E value is 0.022, the chromaticity value is 0, and the acidity is 0.022mmol/kg.
By adopting the method provided by the invention, the caprolactam has higher yield under the premise of ensuring the high purity of the caprolactam. In addition, according to the preferred embodiment provided by the invention, the crude caprolactam product obtained by the cyclohexanone oxime gas-phase Beckmann rearrangement reaction is crystallized by adopting a specific solvent system, so that a more excellent crystallization effect is obtained.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (10)
1. A process for the preparation of caprolactam, the process comprising: carrying out gas-phase Beckmann rearrangement reaction on cyclohexanone oxime to obtain a caprolactam crude product, and then crystallizing the caprolactam crude product, wherein the crystallization temperature is 15-50 ℃; the solvent used for crystallization comprises a solvent A and a solvent B, wherein the solubility of caprolactam in the solvent A is more than 25 wt% and the solubility of caprolactam in the solvent B is less than 5 wt%, and the mass ratio of the solvent A to the solvent B is 1: (15-40); the solvent A is methanol;
The method further comprises subjecting the crude caprolactam product to a first hydrogenation reaction prior to crystallization; the first hydrogenation reaction is carried out in the presence of methanol;
Wherein the caprolactam crude product contains caprolactam, cyclohexanone oxime, octahydrophenazine and tetrahydroazepin-2-one and/or isomers of tetrahydroazepin-2-one, and the content of caprolactam is 98-99.6 wt%, the content of cyclohexanone oxime is 0.01-0.5 wt%, the content of octahydrophenazine is 0.01-0.3 wt%, and the total content of isomers of tetrahydroazepin-2-one and tetrahydroazepin-2-one is 0.01-0.3 wt%, based on the total weight of the caprolactam crude product; wherein the solvent B is at least one selected from halogenated hydrocarbon, ether and alkane with 6-12 carbon atoms; wherein,
The halohydrocarbon is at least one of 1-chloropropane, 2-chloropropane, chloro-n-butane, 2-chlorobutane, chloroisobutane, chloro-tert-butane, n-bromopropane, bromoisopropane, 1-bromobutane and 2-bromobutane;
The ether is at least one of methyl ethyl ether, diethyl ether, n-propyl ether, isopropyl ether, n-butyl ether, ethyl butyl ether, ethylene glycol dimethyl ether, vinyl ether, methyl tertiary butyl ether and ethyl tertiary butyl ether;
The boiling point of the alkane with the carbon number of 6-12 is 60-180 ℃ and is at least one of n-hexane, n-heptane, n-octane, n-nonane, methyl hexane, isohexane, isoheptane, isooctane, isononane, cyclohexane, methylcyclopentane and methylcyclohexane;
The solvent is used in an amount of 80 to 120 parts by weight relative to 100 parts by weight of the crude caprolactam product to be crystallized.
2. The method according to claim 1, wherein the alkane having 6 to 12 carbon atoms has a boiling point of 90 to 130 ℃.
3. The process according to claim 1 or 2, wherein the gas phase beckmann rearrangement reaction is carried out in the presence of a molecular sieve catalyst of MFI structure and the crude caprolactam product is obtained by distillation of the reaction product.
4. A process according to claim 3, wherein the conditions of the gas phase beckmann rearrangement reaction comprise: the temperature is 320-450 ℃, the pressure is 0.05-0.5MPa, and the weight hourly space velocity of the cyclohexanone oxime is 0.1-5h -1.
5. The method according to any one of claims 1 or 2, wherein the first hydrogenation reaction is performed in the presence of a hydrogenation catalyst selected from at least one of a nickel-based catalyst, a palladium-based catalyst, and a platinum-based catalyst.
6. The process of claim 5, wherein the first hydrogenation reaction is carried out in the presence of a palladium-based catalyst.
7. The method according to claim 6, wherein the palladium-based catalyst comprises a carrier and palladium and rare earth oxide supported on the carrier.
8. The method of claim 7, wherein the support is activated carbon and the rare earth oxide is an oxide of lanthanum and/or cerium.
9. The process according to claim 7, wherein the content of palladium is 0.1 to 5% by weight and the content of rare earth oxide is 0.2 to 10% by weight, based on the total amount of the palladium-based catalyst.
10. The process of claim 1 or 2, wherein the first hydrogenation reaction conditions comprise: the temperature is 50-150 ℃ and the pressure is 0.2-1.5MPa.
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| CN112159357B (en) * | 2020-10-15 | 2023-05-23 | 浙江恒逸石化研究院有限公司 | Refining method of caprolactam |
| CN114907264B (en) * | 2021-02-10 | 2024-07-09 | 中国石油化工股份有限公司 | Process for refining caprolactam |
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