Lub molecular sieve yog ib yam khoom uas muaj cov qhov me me (qhov me me heev) uas loj sib npaug. Cov qhov me me no zoo ib yam li cov molecule me me, yog li ntawd cov molecule loj tsis tuaj yeem nkag mus lossis raug nqus, thaum cov molecule me dua tuaj yeem nkag mus. Thaum cov molecule sib xyaw ua ke hla lub txaj ruaj khov ntawm cov khoom porous, semi-solid hu ua sieve (lossis matrix), cov khoom uas muaj qhov hnyav molecular siab tshaj plaws (uas tsis tuaj yeem hla mus rau hauv cov qhov me me molecular) tawm hauv lub txaj ua ntej, tom qab ntawd cov molecule me dua. Qee cov molecule sieves siv rau hauv size-exclusion chromatography, ib txoj kev sib cais uas xaiv cov molecule raws li lawv qhov loj me. Lwm cov molecular sieves siv ua desiccants (qee qhov piv txwv suav nrog activated charcoal thiab silica gel).
Qhov pore txoj kab uas hla ntawm lub molecular sieve yog ntsuas hauv ångströms (Å) lossis nanometres (nm). Raws li IUPAC notation, cov ntaub ntawv microporous muaj pore txoj kab uas hla tsawg dua 2 nm (20 Å) thiab cov ntaub ntawv macroporous muaj pore txoj kab uas hla ntau dua 50 nm (500 Å); yog li ntawd, pawg mesoporous nyob hauv nruab nrab nrog pore txoj kab uas hla ntawm 2 thiab 50 nm (20–500 Å).
Cov ntaub ntawv
Cov molecular sieves tuaj yeem yog microporous, mesoporous, lossis macroporous khoom.
Cov khoom siv me me (
●Zeolites (cov zaub mov aluminosilicate, tsis txhob yuam kev nrog aluminium silicate)
●Zeolite LTA: 3–4 Å
●Iav uas muaj qhov nqus tau: 10 Å (1 nm), thiab siab dua
●Cov pa roj carbon uas ua haujlwm: 0–20 Å (0–2 nm), thiab siab dua
●Cov av nplaum
●Kev sib xyaw ua ke ntawm Montmorillonite
●Halloysite (endellite): Muaj ob hom uas pom ntau, thaum hydrated av nplaum qhia txog qhov sib nrug ntawm 1 nm ntawm cov txheej thiab thaum dehydrated (meta-halloysite) qhov sib nrug yog 0.7 nm. Halloysite tshwm sim los ntawm ntuj tsim ua cov thooj voos me me uas nruab nrab 30 nm hauv txoj kab uas hla nrog qhov ntev ntawm 0.5 thiab 10 micrometres.
Cov khoom siv Mesoporous (2–50 nm)
Silicon dioxide (siv los ua silica gel): 24 Å (2.4 nm)
Cov khoom siv macroporous (> 50 nm)
Macroporous silica, 200–1000 Å (20–100 nm)
Cov ntawv thov [hloov kho]
Cov molecular sieves feem ntau siv rau hauv kev lag luam roj av, tshwj xeeb tshaj yog rau kev ziab cov roj ntws. Piv txwv li, hauv kev lag luam roj av (LNG), cov dej hauv cov roj yuav tsum tau txo kom tsawg dua 1 ppmv kom tiv thaiv kev thaiv los ntawm dej khov lossis methane clathrate.
Hauv chav kuaj mob, cov tshuaj molecular sieves siv los ziab cov kuab tshuaj. "Sieves" tau ua pov thawj tias zoo dua li cov txheej txheem ziab ib txwm muaj, uas feem ntau siv cov tshuaj desiccants uas muaj zog heev.
Nyob rau hauv lub sij hawm zeolites, molecular sieves yog siv rau ntau yam kev siv catalytic. Lawv catalyze isomerisation, alkylation, thiab epoxidation, thiab yog siv rau hauv cov txheej txheem kev lag luam loj, suav nrog hydrocracking thiab fluid catalytic cracking.
Lawv kuj siv rau hauv kev lim cov khoom siv cua rau cov khoom siv ua pa, piv txwv li cov uas cov neeg dhia dej thiab cov neeg tua hluav taws siv. Hauv cov ntawv thov zoo li no, cua raug muab los ntawm lub tshuab cua compressor thiab dhau los ntawm lub lim cartridge uas, nyob ntawm seb daim ntawv thov, puv nrog molecular sieve thiab / lossis activated carbon, thaum kawg siv los them cov tank cua ua pa. Kev lim dej zoo li no tuaj yeem tshem tawm cov khoom me me thiab cov khoom tso tawm ntawm compressor los ntawm cov khoom siv cua ua pa.
Kev pom zoo los ntawm FDA.
Lub Koom Haum FDA hauv Tebchaws Meskas tau pom zoo rau sodium aluminosilicate rau kev sib cuag ncaj qha nrog cov khoom siv tau raws li 21 CFR 182.2727 txij li lub Plaub Hlis 1, 2012. Ua ntej qhov kev pom zoo no, European Union tau siv cov molecular sieves nrog cov tshuaj thiab kev sim ywj pheej tau hais tias cov molecular sieves ua tau raws li txhua qhov kev xav tau ntawm tsoomfwv tab sis kev lag luam tsis kam them nyiaj rau kev sim kim heev uas yuav tsum tau txais kev pom zoo los ntawm tsoomfwv.
Kev rov tsim dua tshiab
Cov txheej txheem rau kev rov ua dua tshiab ntawm cov molecular sieves suav nrog kev hloov pauv siab (zoo li hauv cov pa oxygen concentrators), cua sov thiab purging nrog cov roj nqa (zoo li thaum siv hauv ethanol dehydration), lossis cua sov hauv qab lub tshuab nqus tsev siab. Qhov kub ntawm kev rov ua dua tshiab yog txij li 175 ° C (350 ° F) txog 315 ° C (600 ° F) nyob ntawm hom molecular sieve. Qhov sib piv, silica gel tuaj yeem rov ua dua tshiab los ntawm kev ua kom sov nws hauv qhov cub ib txwm mus rau 120 ° C (250 ° F) rau ob teev. Txawm li cas los xij, qee hom silica gel yuav "pop" thaum raug dej txaus. Qhov no yog tshwm sim los ntawm kev tawg ntawm cov silica spheres thaum kov dej.
| Qauv | Qhov loj ntawm lub qhov (Ångström) | Qhov ceev ntawm cov khoom loj (g/ml) | Cov dej uas tau nqus (% w/w) | Kev Siv | |
| 3Å | 3 | 0.60–0.68 | 19–20 | 0.3–0.6 | Kev ziabntawmroj av tawgroj thiab alkenes, kev xaiv adsorption ntawm H2O hauviav rwb thaiv tsev (IG)thiab polyurethane, ziab ntawmroj ethanolrau kev sib xyaw nrog roj av. |
| 4Å | 4 | 0.60–0.65 | 20–21 | 0.3–0.6 | Kev nqus dej hauvsodium aluminosilicateuas tau txais kev pom zoo los ntawm FDA (saibhauv qab no) siv ua lub suab sib xyaw hauv cov thawv kho mob kom cov ntsiab lus qhuav thiab uacov khoom noj khoom haus ntxivmuajTus lej EE-554 (tus neeg sawv cev tiv thaiv kev sib sau ua ke); Zoo siv rau kev ziab dej hauv cov kua kaw lossis cov roj, piv txwv li, hauv kev ntim cov tshuaj, cov khoom siv hluav taws xob thiab cov tshuaj lom neeg uas lwj; kev tshem dej hauv cov tshuab luam ntawv thiab cov yas thiab ziab cov hydrocarbon uas saturated. Cov hom adsorbed suav nrog SO2, CO2, H2S, C2H4, C2H6, thiab C3H6. Feem ntau suav hais tias yog tus neeg sawv cev ziab thoob ntiaj teb hauv cov xov xwm polar thiab nonpolar;[12]kev sib cais ntawmroj avthiabcov alkenes, adsorption ntawm dej nyob rau hauv cov uas tsis-nitrogen rhiab heevpolyurethane |
| 5Å-DW | 5 | 0.45–0.50 | 21–22 | 0.3–0.6 | Kev tshem tawm roj thiab qhov poob qis ntawm cov rojkev tsav dav hlau roj avthiabroj av, thiab kev sib cais ntawm alkenes |
| 5Å me me uas muaj oxygen ntau | 5 | 0.4–0.8 | ≥23 | Tsim tshwj xeeb rau kev kho mob lossis lub tshuab ua pa oxygen noj qab haus huv [xav tau daim ntawv qhia] | |
| 5Å | 5 | 0.60–0.65 | 20–21 | 0.3–0.5 | Kev ua kom qhuav thiab ntxuav huab cua;kev qhuav dejthiabkev tshem tawm sulfurizationntawm cov roj av thiabroj av kua;cov pa oxygenthiabhydrogenkev tsim khoom los ntawmkev nqus dej siabtxheej txheem |
| 10X | 8 | 0.50–0.60 | 23–24 | 0.3–0.6 | Kev nqus dej zoo heev, siv rau hauv kev desiccation, decarburization, desulfurization ntawm roj thiab kua thiab kev sib cais ntawmcov roj hydrocarbon uas muaj ntxhiab tsw qab |
| 13X | 10 | 0.55–0.65 | 23–24 | 0.3–0.5 | Desiccation, desulfurization thiab purification ntawm roj av thiab roj av |
| 13X-AS | 10 | 0.55–0.65 | 23–24 | 0.3–0.5 | Kev tshem tawm cov roj avthiab desiccation hauv kev lag luam sib cais huab cua, kev sib cais ntawm nitrogen los ntawm oxygen hauv cov pa oxygen concentrators |
| Cu-13X | 10 | 0.50–0.60 | 23–24 | 0.3–0.5 | Qab zib(kev tshem tawm ntawmcov thiols) ntawmroj av dav hlauthiab sib xwscov kua hydrocarbons |
Muaj peev xwm nqus tau
3Å
Cov mis tshuaj kwv yees li no: ((K2O)2/3 (Na2O)1/3) • Al2O3 • 2 SiO2 • 9/2 H2O
Qhov piv ntawm silica-alumina: SiO2/ Al2O3≈2
Kev tsim khoom
3A molecular sieves yog tsim los ntawm kev pauv cation ntawmpotassiumrausodiumnyob rau hauv 4A molecular sieves (Saib hauv qab no)
Kev Siv
Cov molecular sieves 3Å tsis nqus cov molecules uas muaj qhov loj dua 3 Å. Cov yam ntxwv ntawm cov molecular sieves no suav nrog kev nrawm nrawm adsorption, muaj peev xwm rov ua dua tshiab ntau zaus, tiv taus kev sib tsoo zoo thiabkev tiv thaiv kev ua qias tuajCov yam ntxwv no tuaj yeem txhim kho ob qho tib si kev ua haujlwm zoo thiab lub neej ntev ntawm lub sieve. 3Å molecular sieves yog cov desiccant tsim nyog hauv kev lag luam roj av thiab tshuaj lom neeg rau kev ua kom roj refining, polymerization, thiab tshuaj lom neeg roj-kua kom qhuav tob.
3Å molecular sieves siv los ziab ntau yam khoom siv, xws liethanol, cua,cov tshuaj txias,roj avthiabcov hydrocarbons tsis muaj rojCov tom kawg suav nrog cov roj tawg,acetylene,ethylene,propylenethiabbutadiene.
3Å molecular sieve siv los tshem tawm dej ntawm ethanol, uas tom qab ntawd tuaj yeem siv ncaj qha ua bio-fuel lossis tsis ncaj qha los tsim ntau yam khoom xws li tshuaj lom neeg, khoom noj, tshuaj, thiab ntau ntxiv. Txij li thaum kev lim dej ib txwm tsis tuaj yeem tshem tawm tag nrho cov dej (cov khoom tsis xav tau los ntawm kev tsim ethanol) los ntawm cov txheej txheem ethanol vim yog kev tsim ntawm ib qhoazeotropentawm kwv yees li ntawm 95.6 feem pua ntawm qhov hnyav, cov hlaws molecular sieve siv los cais ethanol thiab dej ntawm qib molecular los ntawm kev nqus cov dej rau hauv cov hlaws thiab cia cov ethanol hla mus tau yooj yim. Thaum cov hlaws puv dej, qhov kub lossis siab tuaj yeem hloov kho, tso cai rau cov dej raug tso tawm ntawm cov hlaws molecular sieve.[15]
Cov molecular sieves 3Å khaws cia rau hauv chav tsev kub, nrog rau qhov av noo tsis pub tshaj 90%. Lawv raug kaw hauv qab qhov siab txo qis, khaws cia kom deb ntawm dej, kua qaub thiab alkalis.
4Å
Cov mis tshuaj: Na2O•Al2O3•2SiO2•9/2H2O
Qhov sib piv ntawm silicon-aluminium: 1:1 (SiO2/ Al2O3≈2)
Kev tsim khoom
Kev tsim cov 4Å sieve yog qhov yooj yim heev vim nws tsis tas yuav muaj kev kub siab lossis kub heev. Feem ntau cov kua dej ntawmsodium silicatethiabsodium aluminatetau muab sib xyaw ua ke ntawm 80 ° C. Cov khoom siv uas muaj cov kuab tshuaj yog "ua kom nquag" los ntawm "ci" ntawm 400 ° C 4A sieves ua haujlwm ua tus ua ntej rau 3A thiab 5A sieves los ntawmkev pauv pauv cationntawmsodiumraupotassium(rau 3A) los yogcalcium(rau 5A)
Kev Siv
Cov tshuaj yaj kom qhuav
Cov tshuab nqus molecular 4Å siv dav los ziab cov kuab tshuaj hauv chaw kuaj mob. Lawv tuaj yeem nqus dej thiab lwm cov molecule uas muaj qhov tseem ceeb tsawg dua 4 Å xws li NH3, H2S, SO2, CO2, C2H5OH, C2H6, thiab C2H4. Lawv siv dav hauv kev ziab, kev ua kom huv thiab kev ntxuav cov kua thiab cov pa roj (xws li kev npaj argon).
Cov tshuaj ntxiv rau polyester [kho kom raug]
Cov molecular sieves no yog siv los pab cov tshuaj ntxuav vim lawv tuaj yeem tsim cov dej demineralized los ntawmcalciumkev pauv ion, tshem tawm thiab tiv thaiv kev tso cov av qias neeg. Lawv siv dav los hloovphosphorusLub 4Å molecular sieve ua lub luag haujlwm tseem ceeb los hloov sodium tripolyphosphate ua cov tshuaj ntxuav kom txo tau qhov cuam tshuam rau ib puag ncig ntawm cov tshuaj ntxuav. Nws kuj tseem siv tau ua ib qhoxab npumtus neeg sawv cev tsim thiab hauvtshuaj txhuam hniav.
Kev kho cov khib nyiab uas ua rau muaj kev phom sij
4Å molecular sieves tuaj yeem ntxuav cov dej phwj ntawm cov hom cationic xws liammoniacov ions, Pb2+, Cu2+, Zn2+ thiab Cd2+. Vim yog qhov kev xaiv siab rau NH4+ lawv tau siv tau zoo hauv thaj teb los tawm tsamkev hloov pauv ntawm cov khoom siv eutrophicationthiab lwm yam teebmeem hauv cov dej ntws vim muaj ntau dhau ntawm ammonium ions. 4Å molecular sieves kuj tau siv los tshem tawm cov hlau hnyav ions uas muaj nyob hauv dej vim yog kev ua haujlwm hauv kev lag luam.
Lwm lub hom phiaj
Lubkev lag luam hlau: tus neeg sawv cev sib cais, kev sib cais, kev rho tawm ntawm cov kua qaub ntsev,rubidium,caesium, thiab lwm yam.
Kev lag luam roj av,cov tshuaj ua kom lub cev muaj zog,tshuaj desiccant, cov khoom nqus dej
Kev Ua Liaj Ua Teb:tshuaj kho av
Tshuaj: thauj nyiajzeolitetus neeg sawv cev antibacterial.
5Å
Cov mis tshuaj: 0.7CaO • 0.30Na2O • Al2O3 • 2.0SiO2 • 4.5H2O
Qhov piv ntawm silica-alumina: SiO2/ Al2O3≈2
Kev tsim khoom
5A molecular sieves yog tsim los ntawm kev pauv cation ntawmcalciumrausodiumnyob rau hauv 4A molecular sieves (Saib saum toj no)
Kev Siv
Tsib-ångström(5Å) cov molecular sieves feem ntau siv rau hauvroj avkev lag luam, tshwj xeeb tshaj yog rau kev ntxuav cov roj ntws thiab hauv chav kuaj tshuaj rau kev sib caiscov tshuaj sib xyawthiab cov khoom siv pib ua kom qhuav. Lawv muaj cov qhov me me ntawm qhov loj me thiab sib npaug, thiab feem ntau yog siv los ua cov khoom nqus rau cov pa roj thiab kua.
Cov sieve molecular tsib-ångström siv los ziabroj av, nrog rau kev ua yeeb yamkev tshem tawm sulfurizationthiabkev tshem tawm cov pa roj carbon dioxidentawm cov roj. Lawv kuj tseem siv tau los cais cov sib xyaw ntawm oxygen, nitrogen thiab hydrogen, thiab roj-wax n-hydrocarbons los ntawm cov hydrocarbons branched thiab polycyclic.
Cov sieves molecular tsib-ångström khaws cia rau hauv chav tsev kub, nrog rauqhov av noo sib pivtsawg dua 90% hauv cov thawv ntawv lossis cov thawv ntim khoom. Cov molecular sieves yuav tsum tsis txhob raug ncaj qha rau huab cua thiab dej, cov kua qaub thiab alkalis yuav tsum zam.
Morphology ntawm molecular sieves
Cov molecular sieves muaj ntau yam duab thiab qhov ntau thiab tsawg. Tab sis cov hlaws dai spherical muaj qhov zoo dua li lwm cov duab vim lawv muab qhov siab qis dua, tiv taus attrition vim lawv tsis muaj cov npoo ntse, thiab muaj lub zog zoo, piv txwv li lub zog tsoo uas xav tau ib cheeb tsam siab dua. Qee cov beaded molecular sieves muab qhov kub qis dua yog li qhov xav tau lub zog qis dua thaum rov ua dua tshiab.
Qhov zoo ntawm kev siv cov beaded molecular sieves yog qhov ceev ntawm cov khoom feem ntau siab dua li lwm cov duab, yog li rau tib qhov kev xav tau adsorption molecular sieve ntim xav tau tsawg dua. Yog li thaum ua de-bottlenecking, ib tus tuaj yeem siv cov beaded molecular sieves, thauj ntau cov adsorbent hauv tib lub ntim, thiab zam kev hloov pauv ntawm cov hlab ntsha.
Lub sijhawm tshaj tawm: Lub Xya Hli-18-2023
