Dab tsi yog Silica Alumina Ratio ntawm Zeolite Molecular Sieve

Dab tsi yog Silica Alumina Ratio ntawm Zeolite Molecular Sieve?

silica alumina ratio (SiO₂/AlO₃molar ratio) yog qhov tseem ceeb ntawm kev tswj hwm qhov tseem ceeb rau kev ua haujlwm tseem ceeb ntawm zeolite molecular sieves, ncaj qha cuam tshuam rau lawv lub moj khaum stability, acid site tis, thiab pore topology. Cia peb kawm txog hom- yam ntxwv, qauv- kev sib raug zoo ntawm zeolite molecular sieves nrog sib txawv silicon-aluminium ratios, nrog rau lawv daim ntawv thov compatibility hauv petrochemicals, kev tiv thaiv ib puag ncig, thiab lwm yam.

Txhais ntawm Silica Alumina Ratio

• silica alumina ratio yog hais txog molar ratio lossis atomic ratio (Si/Al) ntawm silicon -oxygen tetrahedron (SiO)₄) rau aluminium-oxygen tetrahedron (AlO₄) nyob rau hauv molecular sieve molecular. Thiab nws tus nqi txiav txim siab tus nqi ceev ntawm lub moj khaum, thiab txoj kev them nyiaj cation.
• Tsawg silica alumina piv molecular sieve muaj cov nqi tsis zoo siab nyob rau hauv lub moj khaum, thiab yuav tsum tau them nyiaj ntau ntawm cation. Lub moj khaum ntawm siab silica alumina piv molecular sieve yog dominated los ntawm muaj zog Si-O-Si bonds, thiab nws topological qauv yog heev thermal stability. Lub silica alumina ratio tswj cov kua qaub zog, pore loj faib thiab hydrophobicity ntawm molecular sieve, ua rau nws haum rau txawv kev lag luam scenarios.

Kev faib tawm ntawm Zeolite Molecular Sieve

Txoj Cai Mechanism Ntawm Silica Alumina Ratio

• Acidity regulation: Aluminium atoms yog qhov chaw ntawm Brønsted acid sites, thiab silica alumina ratio ncaj qha cuam tshuam cov acid ntom thiab lub zog: Thaum cov silica alumina piv nce los ntawm 20 mus rau 150, tag nrho cov nqi ntawm cov acids tsis muaj zog (desorption ntawm 120 degree) thiab muaj zog acid qhov chaw SM 5 ntawm 400℃desorption. 40%. Qhov kev faib ua feem ntawm qhov chaw muaj zog acid nyob rau hauv siab silica alumina piv (xws li ZSM-5-300) txo qis, inhibiting hydrogen hloov sab cov tshuaj tiv thaiv, thiab propylene selectivity nce mus rau 81.5%.
• Pore ​​qauv thiab adsorption kev ua tau zoo: Thaum silica alumina piv ntawm ZSM-22 molecular sieve nce los ntawm 40 mus rau 130, lub pore ntim thawj zaug nce mus rau 0.25 cm.³/g thiab tom qab ntawd shrinks mus rau 0.18 cm³/g, because the framework shrinkage is aggravated under high silicon conditions. ZSM-5 molecular sieve with a silica alumina ratio of >100 muaj peev xwm adsorption ntawm 41 mg / g rau toluene, uas yog 70% siab dua li ntawm ZSM-5 nrog ib tug silica alumina piv ntawm 38, vim hais tias lub enhanced hydrophobicity txo cov kev sib tw adsorption ntawm dej molecules.
• Thermal stability thiab hydrothermal durability: Tsawg- silicon Y- hom (SiO₂/Al₂O₃=2) ua rau lub cev pob txha tawg ntawm 660 degree, thaum siab -silicon ZSM-5 (SiO₂/Al₂O₃>30) tuaj yeem tiv taus kub txog 900 degree. Thaum cov silica alumina piv nyob rau hauv lub Cu / SSZ-13 catalyst nce los ntawm 6 mus rau 16, SCR kev ua si tuav tus nqi nce los ntawm 45% mus rau 85% tom qab hydrothermal kev kho mob ntawm 800℃/ 16h, vim qhov txo nyob rau hauv tus nqi dealumination.

Silica Alumina Ratio Adaptation Strategy Nyob rau hauv Industrial Applications

• Kua catalytic cracking (FCC): Thaum lub silica alumina piv ntawm USY molecular sieve yog 6-8, lub coke selectivity txo los ntawm 2.5 feem pua ​​cov ntsiab lus thiab lub teeb roj tawm los ntawm 3%.
• Methanol rau olefins (MTO): Thaum silica alumina piv ntawm SAPO-34 molecular sieve yog 0.3-0.5, ethylene / propylene selectivity nce mus txog 80%. High silica alumina ratio ua rau cov pa roj carbon deposition ntawm polycyclic aromatic hydrocarbons thiab ua rau deactivation.
• VOCs adsorption: Lub peev xwm adsorption ntawm ZSM-5 molecular sieve nrog silica alumina piv ntawm 300 rau benzene series yog 120 mg / g, thiab lub sij hawm nkag mus rau 66 min, uas zoo dua li 40 mg / g ntawm activated carbon.
• NOx tshem tawm: Thaum silica alumina piv ntawm Cu / LTA catalyst yog 16-23, NOx hloov pauv tus nqi tseem nyob ntawm 90% tom qab hydrothermal aging ntawm 600 degree, uas muaj ob qho tib si kev ua haujlwm siab thiab ua haujlwm ntev.
• Kev tswj cov tshuaj tso tawm: Tsawg silica alumina piv (1.5 ~ 2.0) hom A zeolite molecular sieve ua tiav kev tso tawm ntawm ibuprofen los ntawm kev tswj qhov pore loj, nrog rau 24h tso tawm tus nqi ntawm 95%.
• CO₂capture: Amine-functionalized type X zeolite molecular sieve (silica alumina ratio 2.5) tswj cov CO₂adsorption muaj peev xwm ntawm 12 wt% nyob rau hauv cov av noo, thiab nws cov dej tsis kam yog nce 3 zaug.