Xylene Isomers yog dab tsi?
Xylene, los yog dimethylbenzene, muaj nyob rau hauv peb lub cev isomers: ortho-xylene (o-xylene), meta-xylene (m-xylene), thiab para-xylene (p-xylene). Tag nrho peb qhov sib koom ntawm cov mis mos molecular C8H10 thiab qhov hnyav molecular ntawm 106.17 g / mol, tab sis ob pawg methyl txuas ntawm ntau txoj haujlwm ntawm lub nplhaib benzene. Hauv o-xylene pawg methyl zaum ntawm cov pa roj carbon monoxide, 1,2- txoj haujlwm; hauv m-xylene ntawm carbons sib cais los ntawm ib lub nplhaib carbon, 1,3-txoj hauj lwm; thiab hauv p-xylene ntawm cov pa roj carbon monoxide, 1,4-txoj hauj lwm. Cov kev sib txawv ntawm qhov sib txawv no hloov qhov sib luag ntawm cov molecule thiab, nrog rau nws, cov khoom ntawm lub cev thiab cov nqi lag luam ntawm txhua isomer.
Dab tsi yog o-Xylene thiab p-Xylene?
Ortho-xylene, los yog 1,2-dimethylbenzene, yog cov tsis muaj xim, me ntsis oily kua nrog ib tug qab zib aromatic tsw. Nws qhov qis molecular symmetry tiv thaiv cov khoom siv lead ua nruj, yog li nws tseem ua kua dej mus txog li -25℃. Kev lag luam, o-xylene yuav luag tsuas yog hloov pauv los ntawm catalytic oxidation rau phthalic anhydride (PA), ib qho nruab nrab rau phthalate plasticizers, alkyd resins, thiab unsaturated polyester resins. Cov nyiaj me me yog siv los ua cov kuab tshuaj muaj kuab heev.
Para-xylene, los yog 1,4-dimethylbenzene, yog cov kua tsis muaj xim uas ua kom muaj zog nyob ze 13℃vim tias nws cov qauv sib xyaw ua ke tau zoo rau hauv cov muaju. Nws yog qhov tseem ceeb tshaj plaws xylene isomer vim nws yog cov khoom noj rau purified terephthalic acid (PTA) los ntawm catalytic oxidation. PTA yog tom qab ntawd polymerized nrog monoethylene glycol rau hauv polyethylene terephthalate (PET), siv rau lub raj mis haus, polyester fibers, thiab ntim zaj duab xis. Ntau tshaj 95% ntawm ntiaj teb p-xylene xav tau yog tsav los ntawm PTA-PET saw.
Kev sib piv ntawm o-Xylene thiab p-Xylene
| Khoom | o-Xylene (CAS 95-47-6) | p-Xylene (CAS 106-42-3) |
| Qauv | 1,2-dimethylbenzene, uas nyob ib sab methyl pawg | 1,4-dimethylbenzene, opposite pawg methyl |
| Cov mis mos molecular | C8H10 | C8H10 |
| Boiling point | 144.4 degree | 138.4 hli |
| Melting point | -25.2 ° C | 13.2°C dej |
| Qhov ceev ntawm 20 degree | 0.880g / cm3 | 0.861 g / cm3 |
| Flash point (lub khob kaw) | Txog 32 degree | Txog 27 degree |
| Cov khoom tseem ceeb oxidation | Phthalic anhydride (PA) | Terephthalic acid (PTA) |
| Cov kev lag luam tseem ceeb hauv qab | Plasticizers, alkyd resins, unsaturated polyester | PET resin, polyester fiber, ntim zaj duab xis |
| Lub cev lub cev ntawm 20 degree | Ua kua | Ua kua, ze nws qhov chaw khov |
Symmetry tswj tus cwj pwm melting. Lub para isomer yog qhov sib npaug, yog li nws cov molecules ntim rau hauv cov iav siv lead ua tsis tu ncua yooj yim thiab cov ntsiab lus melting yog qhov siab ntawm li 13 degree. Lub ortho isomer yog asymmetric, uas cuam tshuam cov ntim thiab ua kom nws cov kua mus txog li -25℃. Qhov sib txawv no tseem ua rau muaj kev sib cais ntawm kev lag luam: vim hais tias cov ntsiab lus kub ntawm xylene isomers txawv ntawm ob peb degrees, yooj yim distillation tsis zoo, thiab p-xylene rov qab los ntawm fractional crystallization, xaiv adsorption ntawm zeolite molecular sieves, los yog daim nyias nyias thiab hybrid txheej txheem, ua raws li isomerination.
Cov ntawv thov kev lag luam thiab tus nqi saw
o-Xylene yog oxidized nrog cua tshaj ib tug vanadium-raws li catalyst rau phthalic anhydride, uas yog esterified nrog cawv xws li 2-ethylhexanol los tsim plasticizers rau saj zawg zog PVC thiab nrog polyols tsim alkyd thiab unsaturated polyester resins. p-Xylene yog oxidized nyob rau hauv cov kua theem mus rau terephthalic acid, uas yog purified thiab polymerized rau PET. PET thiab polyester kev lag luam yog cov lag luam polymer loj tshaj plaws hauv ntiaj teb, uas ua rau p-xylene yog qhov muaj txiaj ntsig tshaj plaws xylene isomer. Cov neeg yuav khoom ntawm cov isomer yuav tsum paub meej tias purity, feem ntau 98 mus rau 99% lossis siab dua, cov ntsiab lus dej los ntawm Karl Fischer titration, xim ib ASTM D1209, thiab distillation ntau ntawm ASTM D1078.
Kev nyab xeeb thiab tuav
Ob qho isomers yog cov kua hluav taws xob hluav taws xob thiab cov khoom siv hluav taws xob tsis zoo uas tuaj yeem ua rau tawv nqaij, qhov muag, thiab ua pa ua pa, thiab cov pa tawm siab tuaj yeem cuam tshuam rau hauv nruab nrab lub paj hlwb. Khaws lawv kom deb ntawm qhov hluav taws kub, hauv av tag nrho cov cuab yeej hloov chaw tiv thaiv cov pa tawm zoo li qub, thiab siv qhov cua thiab tsim nyog PPE. Vim p-xylene solidifies ze 13 degree, cia tso tsheb hlau luam thiab hloov kab yuav tsum tau cua sov nyob rau hauv cov huab cua txias. Khaws ob qho khoom lag luam hauv cov thawv ntim rau hauv qhov chaw txias, zoo- qhov chaw cua, thiab tuav cov khoom nchuav nrog cov khoom nqus dej ua raws li kev tso cai pov tseg.
Cov lus nug nquag
o-xylene feem ntau yog siv rau dab tsi?o-Xylene (CAS 95-47-6) feem ntau yog oxidized rau phthalic anhydride, uas yog siv los tsim phthalate plasticizers, alkyd resins, thiab unsaturated polyester resins.
P-xylene feem ntau yog siv rau dab tsi?p-Xylene (CAS 106-42-3) yog cov khoom noj tseem ceeb rau purified terephthalic acid (PTA), uas yog polymerized rau hauv PET rau lub raj mis, polyester fibers, thiab ntim zaj duab xis.
Vim li cas p-xylene ua lag luam muaj txiaj ntsig ntau dua li o-xylene?Vim p-xylene pub rau PTA-PET tus nqi saw, yog ib lub lag luam polymer loj tshaj plaws hauv ntiaj teb, thaum o-xylene pub cov phthalic anhydride thiab plasticizer me me ua lag luam.
Vim li cas o-xylene kua nyob rau hauv chav tsev kub tab sis p-xylene tuaj yeem ua kom khov?Lub symmetrical 1,4- qauv ntawm p-xylene ntim tau zoo rau hauv cov muaju thiab yaj nyob ze ntawm 13 degree, thaum lub asymmetric 1,2-cov qauv ntawm o-xylene tiv thaiv cov ntim nruj thiab nyob twj ywm kua rau txog -25℃.
o-xylene thiab p-xylene puas tuaj yeem sib cais los ntawm distillation?Tsis yog economic. Lawv cov ntsiab lus boiling tsuas yog ob peb degrees sib nrug, yog li kev lag luam sib cais siv crystallization, xaiv adsorption, lossis cov txheej txheem hybrid, feem ntau ua ke nrog isomerization.
Dab tsi yog cov cuab yeej tiv thaiv uas xav tau thaum tuav xylene isomers?Tshuaj lom neeg- hnab looj tes tiv taus, tsom iav kev nyab xeeb, thiab cov khaub ncaws tiv thaiv, nrog rau qhov cua txaus lossis kev tiv thaiv ua pa uas muaj vapor concentration ntau. Cov av yuav tsum tau ua thaum hloov mus.