Kev siv dav ntawm cov khoom siv zeolite molecular sieve (xws li kev sib cais adsorption, ion pauv, catalysis) yog ze rau lawv cov yam ntxwv ntawm cov qauv. Piv txwv li, kev ua haujlwm adsorption thiab kev sib cais yog nyob ntawm qhov loj ntawm qhov pores thiab pore ntim ntawm molecular sieve; Kev sib pauv ion yog nyob ntawm tus naj npawb thiab txoj haujlwm ntawm cations hauv molecular sieve, nrog rau kev nkag mus ntawm nws cov pore raws; Cov duab xaiv tau nthuav tawm thaum cov txheej txheem catalytic muaj feem xyuam rau qhov pore loj thiab kev taw qhia ntawm molecular sieve, thaum lub pore loj lossis tawb qauv ntawm cov khoom nruab nrab thiab cov khoom kawg hauv cov tshuaj tiv thaiv catalytic cuam tshuam nrog cov molecular sieve. Yog li, cov qauv ntawm molecular sieves yog qhov teeb meem tseem ceeb hauv kev kawm cov ntaub ntawv molecular sieve.
Chav tsev tsim qauv
Ua ntej, ua kev tshawb fawb ntawm cov qauv yooj yim tshaj plaws. Feem ntau hais lus, zeolite molecular sieves yog tsim los ntawm stacking tetrahedra los ntawm kev sib koom vertices, yog li ib tug tetrahedron yog ib tug thawj structural unit (TO4 tetrahedron). Piv txwv li, rau silicalite-1 zeolite molecular sieve, nws thawj chav tsev yog silicon oxygen tetrahedra ([SiO4] 0), thiab chav tsev tetrahedral no nthuav tawm hluav taws xob neutrality. Cov silicon oxygen tetrahedra txuas nrog cov pa sib koom ua ke los tsim ib lub zeolite molecular sieve nrog MFI qauv. Hauv kev sib xyaw ua ke, cov neeg ua haujlwm template thiab cov dej adsorbed muaj nyob hauv nws qhov pores. Tau kawg, thaum txhuas muaj nyob rau hauv lub synthesis system, muaj ob hom tetrahedra: silicon oxygen tetrahedra ([SiO4] 0) thiab aluminium oxygen tetrahedra ([AlO4] -), thiab txhuas oxygen tetrahedra muaj qhov tsis zoo. nqi. Los ntawm kev sib sau ua ke thiab sib sau ua ke ntawm molecular sieves nrog MFI qauv ntawm silicon thiab txhuas, cov qauv no nws tus kheej muaj qee yam tsis zoo, yog li nws yuav tsum sib npaug los ntawm cov cations ntxiv kom nws qhov kawg hluav taws xob nruab nrab tag nrho. Thiab phosphorus aluminium molecular sieve yog nruj me ntsis tsim los ntawm alternating phosphorus oxygen tetrahedra ([PO4]+) thiab aluminium oxygen tetrahedra ([AlO4] -), nrog rau cov pob txha hluav taws xob nruab nrab. Tau kawg, nyob rau hauv kev sib txuas ntawm cov txheej txheem tseem ceeb, txoj cai Lowenstein yuav tsum tau ua raws li: nyob rau hauv lub silicon aluminium skeleton qauv, txhuas tsis tuaj yeem nyob ib sab; Hauv cov qauv phosphate skeleton, xws li SAPO-34, aluminium tsis tuaj yeem nyob ib sab ntawm divalent lossis trivalent hlau atoms, thiab phosphorus tsis tuaj yeem txuas nrog silicon lossis phosphorus.
tsev kawm ntawv theem nrab
Lub cev pob txha ntawm molecular sieves yog tsim los ntawm finite los yog infinite kev sib txuas ntawm thawj cov qauv units. Finite structural units, xws li lwm yam structural units, feem ntau yog xa mus rau multicomponent nplhaib cov qauv tsim los ntawm TO4 tetrahedra uas sib koom taag-point oxygen atoms thiab txuas nrog ntau txoj kev. Cov qauv ntawm cov nplhaib feem ntau suav nrog plaub lub nplhaib sib koom, tsib lub nplhaib sib koom ua ke, rau lub nplhaib sib koom ua ke, ob npaug plaub lub nplhaib sib koom, thiab ob npaug rau lub nplhaib. Dab tsi tau pom tam sim no yog 18 hom kev teeb tsa theem nrab. Piv txwv li, lub 4-4 theem nrab structural unit sawv cev rau ob quaternary rings, uas yog ob lub quaternary rings. Raws li peb tau paub txog A-hom molecular sieves, lawv tau tsim los ntawm kev sib txuas SOD tawb nrog ob lub voj voog quaternary los tsim zeolite molecular sieves. Tau kawg, SBU peb hais txog tsuas yog ib chav tsev topological hauv kev xav, txhawm rau kom nkag siab zoo dua thiab piav qhia cov qauv ntawm zeolite molecular sieves, thiab tsis tuaj yeem suav tias yog hom tsiaj tiag tiag hauv cov txheej txheem crystallization ntawm zeolite molecular sieves.
Cage zoo li tus qauv chav tsev
Muaj ib lub tawb zoo li cov qauv tsev nyob rau hauv cov pob txha ntawm molecular sieves, uas tau piav qhia raws li ntau lub nplhaib uas txiav txim siab lawv cov polyhedra. Piv txwv li, tus paub SOD tawb yog tsim los ntawm yim hexagonal rings thiab rau quaternary rings, feem ntau abbreviated li 4668. Txawv molecular sieve skeletons yuav muaj tib lub tawb zoo li structural units, nyob rau hauv lwm yam lus, tib lub tawb zoo li structural unit yuav tsim ntau hom. ntawm molecular sieve skeleton qauv los ntawm kev sib txuas sib txawv. Ib qho piv txwv classic yog SOD tawb.
SOD zeolite molecular sieve yog tsim los ntawm coplanar kev sib txuas ntawm SOD tawb; Lub SOD tawb txuas nrog ob lub voj voog quaternary los tsim LTA hom molecular sieves; SOD tawb txuas nrog ob lub nplhaib hexagonal los tsim FAU thiab EMT zeolite molecular sieves.
Tsis tas li ntawd, nyob rau hauv lub moj khaum qauv ntawm zeolite molecular sieves, ib co yam ntxwv chains, ob-dimensional peb txuas network khaubncaws sab nraud povtseg, thiab periodic structural units (PBUs) feem ntau pom. Lub tsib feem ntau cov saw zoo li cov qauv yog Pentasil saw, ob lub zigzag saw, ob lub zigzag saw, ob qag saw, thiab luv kem pob zeb saw. Pentasil saw tsim los ntawm tawb sib koom los ntawm cov npoo yog cov yam ntxwv ntawm cov silica zeolite siab molecular sieve tsev neeg. Tus neeg sawv cev feem ntau cov qauv ntawm MFI yog tsim los ntawm Pentasil chains. Kev sib txuas ntawm ob sab ntawm peb qhov sib txuas sib txuas sib txuas ua ke ua ib qho kev sib txuas ntawm peb-dimensional plaub txuas nrog lub cev pob txha los ntawm kev sib txuas ntawm peb qhov kev sib txuas ntawm qhov sib txuas ntawm qhov taw qhia vertically. Piv txwv li, GIS hom skeleton qauv yog tsim los ntawm 4.82 ob-dimensional network txheej txheej qauv txuas vertically.