LY TRICH KHlT LlTU HUYNH TRONG DAU DIESEL BANG
C H A T L O N GION
NGUVeN TH! BfCH CHl', i t NGQC THACH"
T6M TAT
Mgt so chdt Idng ion chua alkilmetilimidazolium da dugc diiu chi vd sir dung rdt hiiu qud di ly trich nhimg hgrp chdt hiru ca liru huynh trong ddu diesel Viet Nam.
[CeMIJBr dugc nhdn thdy Id tdt hem cd. Anh hu&ng ciia thdi gian, nhiit do vd ti li mol tren su ly trich dd dugc khdo sdt vd toi uu hoa. Kit qud tir su ly trich co oxid hda vd khdng oxid hoa cho thdy rdng cd oxid hda (H2O2, AcOH) cho kit qud tdt han (35%). Chdt long ion co thi thu hoi vd sir dung lgi
Tir khda: chit Idng ion, [CeMIJBr, hgp chit hiiu co luu huynh, ly trich, ddu diesel Vift Nam, su khir luu huynh.
ABSTRACT
Extractive desulfurization of diesel oil by ionic liquid
Some of ionic liquids containing alkylmethylimidazolium are prepared and used efficiently in extraction of organic sulfide compound in diesel oil in Vietnam. [CeMIJBr is regarded as the best The effects of time, temperature and molar ratios on the organic sulfur compound extraction are investigated and optimized. The results from oxidized and non-oxidized extractions show that the extraction with oxidation (H2O2, AcOH) gives the better treatment (35%). The ionic liquid can be recuperated and reused.
Keywords: ionic liquid, [CeMIJBr, organosulfide compound, extraction, Vietiiamese diesel oil, desulfurization.
1. Dat van de
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Khi thdi tir ddng co cua cac phucmg tien giao thdng gdp phdn khdng nhd vdo su tao ra khi SO^, nguyen nhdn gdy d nhilm mdi trudmg va mua acid. Hien nay, cdc qudc gia phdt triln dang khuyin khich vifc ldm gidm hdm lugmg luu huynh trong cdc nhien lifu nhu: ddu diesel (DO), xang [1].
Trudc day, cac nhd khoa hgc da nghien ciiu. lam gidm ham lugmg luu huynh ti-ong ddu diesel vd xdng bdng phdn iing hidrogen hda d dieu kifn dp sudt cao, nhiet do cao vdi cdc xiic tdq ddc bift [2].
Chit Idng ion la mgt chit Idng thi hf mdi cd nhilu ddc dilm hom cdc dung mdi huu CO truyen thdng nhu hda tan chgn lgc, bin, cd dilm sdi rit cap nen tranh dugc that thodt khi tiln hdnh ly trich. Sau khi sir dyng, chit Idng ion cd thi thu hdi, tinh chl dl ddng vd tdi sii dyng ma boat tinh khdng thay doi [3].
CN, Trudng Dgi hpc Khoa hoc Tu- nhiSn, DHQG TPHCM
* GS TS, Trudng Oai hoc Khoa hoc Ty nhi^n, DHQG TPHCM
Tap chi KHOA HOC DHSP TPHCM Sd 30 ndm 2011
Trong bdi bdo ndy, chiing tdi gidi thifu mgt phuong phdp lam gidm hdm lugng hgp chit luu huynh huomg phuomg trong ddu diesel bdng phucmg phdp ly trich siir dyng chdt Idng ion (ionic liquyd, IL). Ddy Id mgt phuomg phdp rit mdi dya tren sy tao phirc chit ylu giiTa hgp chit huomg phuomg - chit Idng ion (do tuomg tac dien tiir n-n gifta nhdn huong phuong vd nhdn imidazolium) [4].
Hifn nay, vifc nghien ciiru ndy cd tinh thdi sy vi ddy Id mgt phuong phdp "xanh"
dl ldm gidm hdm lugmg hgp chit luu huynh trong xdng dau (SciFinder, thdng 2/2010) [5].
2. Thyc nghifm
Sy klido sdt dugc thyc hifn tren dau diesel dang luu hdnh d thj trudng Vift Nam.
Hdm lugng luu huynh trong dau diesel dugc xdc djnh bdn^ thilt bj phdn tich luu huynh RX-350 SH (Trung tdm Nghien curu vd Phdt triln Che biln Dau khi). Hdm lugmg luu huynh trong mdu ddu diesel ndi tren dugc xdc djnh la 4079 ppm. Ti trgng va do nhdt cua dau diesel dugc xdc djnh bdng ti trgng kl thiiy tinh vd nhdt kl Ostwald.
Cdc chit Idng ion sii dyng dugc dilu chl theo tdi lifu tham khdo [6].
Quy ti"inh ly trich dugc thyc hifn theo so dd 1.
Xac djnh ham lUgfng S
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Sff dd 1. Quy trinh ly trich hgrp chdt luu huynh trong ddu diesel
Thyc nghifm tong quat: Cho vdo binh clu DO vd IL tiieo ti If khdo sdt. Nlu cd kit hgp vdi sy oxid hda thi cho tiiem H2O2 vd acid acetic. Ddt tit cd len mdt mdy dun khuiy tir dilu nhift vdi nhift dg, thdi gian, van tdc khuiy nhlt djnh. Sau khi tiln hdnh ly trich, hon hgp sdn pham dugc dh yen, sau dd ly tdm dl sy tdch idp dugc hoan todn.
3. Ket qua vd thao luan 3.1. Chgn chdt Idng ion
Cd djnh tam thdi cdc dilu kien ly trich:
Ti If khdi lugng DO:IL Id 2:1, - Khuiy tir,
60 °C.
Thay ddi ldn lugt cac chit Idng ion. Ket qud dugc ghi trong bang 1.
Bdng 1. Hdm lugrng luu huynh trong ddu diesel sau khi ly trich v&l mpt so chdt long Ion
Stt 1 2 3 4 5 6 7 8
Chit Idng ion * [C2MI]BF4 [C4MIJBF4 [C6MIJBF4 fC8MIlBF4 [C2MI]Br [C4MI]Br [C6MI]Br [CgMIJBr
S (ppm) 4050 3980 3854 3780 3920 3943 3897 3761
*[CnMI]PF4 vd [CnMIJBr lan lugt Id tetrafluorophosphat l-alkil-3- metilimidazolium vd bromur l-alkil-3-metilimidazolium.
Ket qud tren cho thay co cau ciia chat Idng ion cd dnh hudng den kha nang ly trich. Day alkil cdng ddi thi khd ndng ly trich hgp chat luu huynh cdng cao, [CgMI] cho kit qud ly trich hgp chat luu huynh tdt nhlt. Nhung khd ndng ly trich giiia [C6MI]Br vd [CgMIJBr chenh Ifch khdng ddng kl, ma [CgMIJBr cd hifu suit dilu chl thudng thlp hon [CgMIJBr trong cimg dilu kien [6]. Do do, chiing tdi quyet djnh chgn [CglVlIJBr de khdo sat tiep tyc.
3.2. Ly trich khdng kit hgp oxid hda
Lln lugt khdo sat ba ylu td (ti If khdi lugng, thdi gian, nhift do) cd anh hudng din kit qud ly trich, chiing tdi thu dugc dieu kifn ly trich tdi uu nhu sau:
- Ti If khdi lugng DO:IL la 1:1, Khuiy tir,
- 15 phiit, - 50 °C.
Vdi dieu kifn nay, sau khi ly trich thi ham lugng luu huynh trong ddu diesel cdn lai Id 3750 ppm. Hieu suit ly trich, H (%), dugc tinh bdng cdng thiic sau:
. (5„-<S)_ (4079-3750)
H X 100% = 8,06%.
S„ 4079
Vdi So: ham lugng luu huynh trong diu diesel ban dau S: hdm lugng luu huynh trong ddu diesel sau khi ly trich
Tap chi KHOA HOC DHSP TPHCM Sd 30 ndm 2011
Ket qua tren cho thay d dieu kifn tdi uu khd ndng ly trich ciia chdt Idng ion [CgMIJBr vdn chua cao (8,06 %). Dd la ly do md chiing tdi tiln hdnh khdo sat ly trich hgp chdt luu huynh cd kit hgp oxid hda nhdm ldm gia tdng khd ndng ly trich ciia chdt Idng ion.
3.3. Ly trich cd kit hgrp oxid hda [7J
Thay ddi cdc ylu to cd dnh hudmg din sy ly trich nhu tren nhung lan nay cd sy tham dy cua mgt tdc nhdn oxid hda Id H2O2 trong mdi trudng acid acetic, dieu kifn ly trich toi uu dugc xdc djnh lai nhu sau:
- Ti If khdi lugng DO:IL Id 1:1, Khuiy tir,
- 10 gid,
Nhift dg phdng,
- Ti If thi tich H202:CH3COOH Id (2,1:0,75) x 5 ml.
Vdi dilu kifn ndy, sau khi tiln hdnh ly trich, hdm hrgng luu huynh trong dau diesel cdn lai Id 2653 ppm. Hifu suit ly trich tuong img Id:
H(«/,) = ( 1 5 Z | ^ , , 0 0 « / „ = 34,96 «/..
Hifu suit tren cho thdy sy ly trich hgp chit luu huynh cd kit hgp vdi s\r oxid hda cho ket qud tdt hon rit nhilu (34,96 %) so vdi khdng kit hgp oxid hda (8,06 %). Dilu nay dugc gidi thich cd thi Id do hgp chit luu huynh hum co sau khi bj oxid hoa trd nen phan cue hon do dd cd do hda tan trong chit Idng ion tdng len.
Dl ddnh gia su ly trich cd kit hgp oxid hda ciia chit Idng ion [CeMIJBr, chiing toi tien hdnh ly trich nhieu lan theo dilu kifn tdi uu lien tilp len mgt mau DO. Kit qua dugc bieu diln trong dd thj 1.
S (ppm)
So lai) ly Inch
Do thi 1' Ham lugmg luu huynh con lgi trong ddu diesel sau cdc ldn ly trich Do thj 1 cho tiily sau khi lytrich ldn tiiir tu, hdm lugng luu huynh bit ddu khdng thay doi nhieu nhu trudc. Dieu nay cd thi dugc gidi thich la do chit Idng ion ly. trich cd tinh chgn lgc, chi cd tdc dyng tren nhirng hgp chit luu huynh huotig phuong [3J ma"
trong xdng ddu hgp chit luu huynh Id mdt hdn hgp cdc hgp chit chi phuomg va huomg phuong.
Mdt sd chi tieu ciia ddu diesel (hdm lugng luu huynh, ty trgng, do nhdt) dugc xdc dinh trudc vd sau khi ly trich (phuomg phdp ly trich kit hgp oxid hda). Kit qud thu dugc ghi trong bdng 2.
Bdng 2. Mgt s6 chi tieu cua ddu diesel tru&c vd sau khi ly trich Chi tieu
S (ppm) doo (g/ml)
TIDO (CP)
Trudc ly trich 4079
0,8378 5,534
Sau ly trich 2653 0,8383
5,569
Ket qud ciia bdng 2 cho thdy sy ly trich cd dnh hudng khdng ddng kl tdi do nhdt vd ty trgng.
3.4. Thu hdi vd tdi sir dgng
Vifc thu hdi vd tdi sir dyng chit Idng ion cd y nghia rit ldm. Hifu suit thu hdi cao, khd ndng tdi sii dyng ldn se ldm chi phi sdn xult gidm khi dp dyng phuomg phdp ndy vdo thuc te.
3.4.LThuhdi
Vifc khdo sat khd ndng thu hdi dugc thuc hifn tren chit Idng ion sii dyng trong phuomg phdp ly trich cd ket hgp vdi su oxid hda.
Hifu sudt thu hdi (Hthu hai) dugc tinh nhu sau:
HttuhSi = r ^ x l 0 0 % Vdi:
V: Id the tich chdt Idng ion sau khi thu hdi (ml).
VQ: Id thi tich chit Idng ion trudc khi sii dyng (ml).
Ket qud vl hifu sudt thu hdi sau 3 lln thi nghifm nhu sau:
Bdng 3. Higu sudt thu hdi chdt Idng ion sau khi su dung Stt
1 2 3
Hifu suit (%) -^
v; 82,33 81,66
84,33 .w.
Kit qud .ciia bang 3 cho thiy hifu suit thu hdi tuong doi cao sau tinig mdi me ly ti-ich ri6ng bift. Do dd, khi ly trich vdi khdi lugmg l ^ sy hao hyt do thit thoat chdc
chdn se gidm xudng. i''i
Tap chi KHOA HOC DHSP TPHCM S6 30 ndm 2011
3.4.2. Tdi sir dung
Sau khi thu hdi nhu tren, chat Idng ion ndy dugc tdi sir dyng de ly trich. Khd ndng tai sir dyng dugc ghi nhdn thdng qua vifc xdc djnh ham lugmg luu huynh trong 2 mau ddu diesel sau khi ly trich bdng lo^i chit Idng ion ndy (phuong phdp oxid hda, dieu kifn toi uu).
Bdng 4. Hdm lugrng hgrp chdt luu huynh sau khi ly trich bdng chdt Idng ion thu hdi Lan
1 2
S (ppm) 2654 2685
Kit qud tren cho thiy chit Idng ion sau khi thu hdi van cdn cd khd ndng ly trich.
Cho nen, nlu dugc tinh chl trudc khi sir dyng l^i thi kit qud se cdn tdt hon nua.
4. Ket lu^n
Qua nghien cuu, mgt sd kit ludn d?i dugc nit ra nhu sau:
- Khd ndng ly trich hgp chit luu huynh cua chit Idng ion tiiy tiiugc vdo chieu dai ddy alkil: [CgMIJ > [CgMIJ > [C4MIJ > [C2MIJ.
Nhift do cdng cao khd ndng ly trich cdng kem, do nhift dg cdng cao hf thdng phiic chat n-n trd nen linh dgng khdng viing chdc.
- Ly trich cd kem sy oxid hda tdt hon, nhung thdi gian ly trich ddi hon.
- Hifu suit thu hdi tuomg ddi cao.
Chat Idng ion cd the tdi su dyng nhieu ldn.
Do dd sy ly trich hgp chit luu huynh htm co bdn^ chit Idng ion cd till dugc xem Id mdt phuong phdp mdi ddy hiira hen trong tiiong lai de gdp phdn ldm gidm hdm lugng hgp chit luu huynh trong ddu diesel dang sir dyng t^i Vift Nam.
1.
2.
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TAI L i f u THAM KHAO
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(Ngiy Td$ soan nh$n durgc bdi: 05-4-2011; ngdy chip nh$n ddng: 10-6-2011)
