Liquid Phase Transition Mechanism Thiab Bidirectional

Ua kua theem hloov mechanism
Cov txheej txheem ua kua theem hloov pauv tau thawj zaug los ntawm Kerr thiab Ciric, yuav luag tib lub sijhawm raws li cov txheej txheem hloov pauv hloov pauv. Lawv ntseeg hais tias cov nucleation thiab kev loj hlob ntawm zeolite molecular sieve crystals yog nqa tawm ncaj qha nyob rau hauv cov kev daws, cov thawj gel maj mam yaj mus rau hauv cov tshuaj, thiab cov active hom aluminosilicate ions yog generated, thiab ces condensation tshwm sim, maj mam tsim cov structural units yuav tsum tau. zeolite molecular sieves, thiab ces ntxiv generating zeolite molecular sieves.
Ua ntej, tom qab cov ntaub ntawv raw xav tau rau zeolite molecular sieves yog sib xyaw, cov hom tseem ceeb silicate thiab aluminate polymerize los ua ib qho kev pib aluminosilicate gel. Lub aluminosilicate gel no tau tsim sai heev nyob rau hauv cov kev mob siab siab, yog li nws muaj kev tsis sib haum xeeb, tab sis lub aluminosilicate gel no tuaj yeem muaj qee yam qauv, xws li plaub-membered rings, rau-membered rings, thiab lwm yam. Tib lub sijhawm, Qhov sib npaug sib npaug yog tsim los ntawm cov gel thiab cov kua theem. Tsis tas li ntawd, cov khoom solubility ntawm aluminosilicate ions yog ze ze rau cov qauv thiab qhov kub thiab txias ntawm gel. Raws li qhov kub ntawm crystallization hloov, ib qho gel tshiab thiab cov tshuaj sib npaug yog tsim los ntawm cov gel no thiab cov kua theem. Qhov thib ob, qhov nce hauv cov concentration ntawm polysilicate thiab aluminate nyob rau hauv cov kua theem ua rau tsim cov siv lead ua nuclei, ua raws li kev loj hlob ntawm zeolite molecular sieve crystals. Thaum lub sij hawm nucleation thiab siv lead ua kev loj hlob ntawm zeolite molecular sieves, polysilicate thiab aluminate ions nyob rau hauv cov kua theem tau noj, ua rau cov silica-alumina gel txuas ntxiv. Txij li thaum lub solubility ntawm zeolite muaju yog tsawg dua li ntawm amorphous gel, qhov kawg tshwm sim yog kev ua tiav ntawm cov gel thiab kev loj hlob ntawm zeolite molecular sieve crystals.
Zhdanov qhov kev sim qhia tau hais tias qhov kev loj hlob ntawm zeolite molecular sieve muaju muaj feem cuam tshuam nrog cov concentration ntawm polysilicate thiab aluminate ions nyob rau hauv cov kua theem, thiab cov concentration ntawm txhua yam nyob rau hauv cov kua theem yog tas li hloov nyob rau hauv lub crystallization txheej txheem. Cov txiaj ntsig kev sim no txhawb nqa cov kua theem hloov tshuab. Cov ntaub ntawv pov thawj zoo tshaj plaws ntawm cov kua theem hloov pauv yog qhov ncaj qha crystallization ntawm zeolite molecular sieves los ntawm cov kua theem. Koizumi et al. ncaj qha synthesized zeolite molecular sieves xws li SOD, GIS, thiab FAU los ntawm cov kev daws teeb meem.
Ob-theem kev hloov mechanism
Thaum tib neeg tseem tab tom sib cav txog seb zeolite molecular sieve crystallization yog los ntawm cov kua theem hloov pauv los yog cov txheej txheem hloov pauv, cov kws tshawb fawb tau npaj ob-theem kev hloov pauv mechanism tom qab xyoo 1980s. Ob-theem kev hloov pauv kev ntseeg tau hais tias kev hloov pauv ntawm cov kua theem thiab cov theem hloov pauv muaj nyob ib txhij nyob rau hauv cov txheej txheem crystallization ntawm zeolite molecular sieve, uas tuaj yeem tshwm sim hauv ob lub crystallization cov tshuaj tiv thaiv sib cais los yog hauv ib qho system tib lub sijhawm.
Gabelica et al. lees paub qhov muaj nyob ntawm ob-theem kev hloov pauv mechanism los ntawm lawv cov kev tshawb fawb ntawm crystallization ntawm ZSM-5 molecular sieve thiab Na Y zeolite. Ib et al. thawj zaug siv lub kaum ntse ntse neutron scattering thev naus laus zis los kawm cov txheej txheem crystallization ntawm ZSM-5 molecular sieve, thiab pom tias crystallization ntawm ZSM-5 zeolite molecular sieve ua raws cov txheej txheem sib txawv thaum siv cov khoom siv sib txawv. Yog li ntawd, nws tau txiav txim siab tias txawm tias tib hom zeolite molecular sieve siv, nws txoj kev loj hlob yog txawv raws li qhov sib txawv crystallization.