Hauv txhua txoj kev lag luam ntawm kev tsim cov syngas, nws yog ib qho tseem ceeb uas yuav tsum siv qhov kev nce qib ntawm cov dej roj hloov pauv cov tshuaj tiv thaiv kom hloov CO mus rau hauv hydrogen.
Qhov kev tshuaj tiv thaiv no yog ib qho kev tshuaj tiv thaiv exothermic uas rov qab tau. Qhov kub siab dua, qhov kev hloov pauv sib npaug qis dua. Tib lub sijhawm, qhov kev tshuaj tiv thaiv no yog ib qho kev tshuaj tiv thaiv catalytic ib txwm muaj. Thaum tsis muaj catalyst, nws nyuaj rau tshuaj tiv thaiv ntawm 700. Thaum muaj catalyst, qhov kub ntawm kev tshuaj tiv thaiv raug txo qis heev. Thaum siv catalyst hloov pauv kub siab, qhov kub ntawm kev tshuaj tiv thaiv yog 300 ~ 500 ° C; Thaum siv catalyst hloov pauv kub qis, qhov kub ntawm kev tshuaj tiv thaiv yog 200-400 ° C (rooj 22). Vim tias qhov kev tshuaj tiv thaiv yog ib qho kev tshuaj tiv thaiv isomolecular, qhov siab tsis muaj feem cuam tshuam rau qhov sib npaug ntawm kev tshuaj tiv thaiv, tab sis kev ua haujlwm siab tuaj yeem txhim kho qhov muaj zog ntau lawm thiab qhov nrawm ntawm kev tshuaj tiv thaiv.
Thaum pib ntawm qhov kev tshuaj tiv thaiv, cov txheej txheem nyob deb ntawm qhov sib npaug thiab raug tswj los ntawm kinetics. Kev nce qhov kub tuaj yeem txhim kho qhov nrawm ntawm kev tshuaj tiv thaiv thiab txhim kho cov txheej txheem ua haujlwm zoo. Hauv theem tom qab ntawm qhov kev tshuaj tiv thaiv, kev hloov pauv ntawm cov txheej txheem raug txwv los ntawm thermodynamic equilibrium. Kev hloov pauv thermodynamic equilibrium ntawm qhov kub siab yog qhov tsawg heev. Yog li ntawd, nyob rau theem tom qab ntawm qhov kev tshuaj tiv thaiv, kev ua haujlwm kub qis yuav tsum tau txais los txhim kho kev hloov pauv CO. Cov yam ntxwv thermodynamic thiab kinetic ntawm cov txheej txheem txiav txim siab tias cov txheej txheem hloov pauv CO yuav tsum tau txais kev ua haujlwm kub hloov pauv.
Thaum pib ntawm qhov kev tshuaj tiv thaiv, cov txheej txheem nyob deb ntawm qhov sib npaug thiab raug tswj los ntawm kinetics. Kev nce qhov kub tuaj yeem txhim kho qhov nrawm ntawm kev tshuaj tiv thaiv thiab txhim kho cov txheej txheem ua haujlwm zoo. Hauv theem tom qab ntawm qhov kev tshuaj tiv thaiv, kev hloov pauv ntawm cov txheej txheem raug txwv los ntawm thermodynamic equilibrium. Kev hloov pauv thermodynamic equilibrium ntawm qhov kub siab yog qhov tsawg heev. Yog li ntawd, nyob rau theem tom qab ntawm qhov kev tshuaj tiv thaiv, kev ua haujlwm kub qis yuav tsum tau txais los txhim kho kev hloov pauv CO. Cov yam ntxwv thermodynamic thiab kinetic ntawm cov txheej txheem txiav txim siab tias cov txheej txheem hloov pauv CO yuav tsum tau txais kev ua haujlwm kub hloov pauv.
Vim muaj kev txwv ntawm qhov sib npaug ntawm cov tshuaj tiv thaiv, txawm hais tias CO raug hloov pauv tob tom qab hloov pauv roj dej kub qis, nws cov ntsiab lus tseem yog li 1%, uas tsis tuaj yeem ua tau raws li qhov xav tau ntawm ntau cov txheej txheem tom qab. Hauv kev lag luam, nws feem ntau raug tshem tawm los ntawm qee cov tshuaj tiv thaiv. Kev xaiv oxidation ntawm CO thiab O2 nyob rau hauv qhov muaj ntau ntawm hydrogen tsim CO2, thiab hydrogen thiab O2 kuj yooj yim rau kev tiv thaiv. Yog li ntawd, cov txheej txheem nruj me ntsis nyob ntawm qhov kub ntawm cov tshuaj tiv thaiv thiab hom catalyst [29301].
Lwm cov txheej txheem kev lag luam yog hydrogenation ntawm CO2 nrog ntau cov hydrogen uas twb muaj lawm ncaj qha rau ntawm nickel raws li catalyst los tsim methane.
Tom qab hloov pauv roj dej thiab tshem tawm CO, cov khoom tseem ceeb ntawm cov roj ua H2 thiab CO2. Hauv kev lag luam ammonia tsim, CO2 yuav tsum tau sib cais ua ntej. Cov CO2 no tuaj yeem txuas ntxiv mus cuam tshuam nrog ammonia tsim los ntawm hydrogen hauv ntu tom ntej los tsim ammonium bicarbonate, ammonium carbonate lossis urea thiab lwm yam chiv kom paub txog kev siv CO2 ntau tshaj plaws. Hauv cov txheej txheem no, cov txheej txheem sib cais ntawm CO2 thiab H2 yog qhov tseem ceeb kom ntseeg tau tias CO2 tuaj yeem siv rov qab.
Rau cov kev siv hydrogen xws li cov roj proton membrane, tsuas yog siv hydrogen xwb es tsis siv CO2. CO2 dhau los ua cov pa phem tsis muaj txiaj ntsig, uas yuav tsum tau ua ke nrog lwm cov txheej txheem mineralization (xws li kev tsim cov calcium carbonate qib zaub mov).
Txawm li cas los xij, hauv txhua txoj kev sib cais CO2, nws yog ib txoj hauv kev zoo dua los siv cov organic amine lossis methanol los nqus CO2. Tshwj xeeb tshaj yog nyob rau hauv cov txheej txheem ntawm CO2 nqus los ntawm methanol ntawm qhov kub qis, qhov solubility ntawm ntau cov pa roj yuav ua rau siab dua ntawm qhov kub qis. Tsuas yog qhov solubility ntawm hydrogen tsis txwv los ntawm qhov kub thiab txias, thiab qhov kub qis dua, qhov solubility qis dua. Nws qhia tau tias muaj kev xaiv zoo rau kev sib cais H2.
Thaum lub sijhawm rov qab tau CO2, xav kom tsis txhob muaj kev puas tsuaj rau cov khoom siv hydrogen, sim tsis txhob siv cov tshuaj reagents kim (xws li caustic soda) uas tuaj yeem sib xyaw nrog CO, kom ntseeg tau tias cov txheej txheem kev lag luam zoo.
Lub sijhawm tshaj tawm: Lub Kaum Ob Hlis-10-2021