Nghien cuu logi luu huynh trong xdng bdng phuong phdp hd'p phu sCr dung zeollt X
TS. Nguyin Anh Dung Trudng Dai hgc Md - Dia eft ThS. Cao Thj Thu Hing
Win Ddu khi Viit Nam
Bdi bdo nghiin cdu qud trinh hdp phu Idu huynh (3Methylthlophene (3-MT), Benzothiophene (BT)) bdng NiX. NiX dupc tong hpp bdng phuang phdp trao ddi ion tCfNaX. Kit qud thUc nghiim cho thdy, vdi ciing mdt the tich mao quAn, NIX cd khd ndng hdp phu lUu huynh tdt han so vdi NaX do sU hinh thdnh ciia phvfc n gluTa lUu huynh vd NP\ DUdng ddng nhiet hdp phu cua qud trinh hdp phu luu huynh {3-MT vd BT) bing NIX cd dang Langmuir dan ldp. Cdu true phin tdchdt chda lUu huynh dnh hudng manh tdi khd ndng hdp phu luu huynh cua NiX. LUpng 3-MT hdp phu tSl da (mmol- S/g - chdt hdp phu) nin NiX Idn hcfn BT do 3-MT cd kich thUdc phdn ttf nhd htm. Tuy nhien, d viing ndng dd cdn bing thdp, BTcd di lUc hdp phu vdi NiX Idn hc/n 3-MT do BT cd mdt dd electron cao hem trong cdu triic phdn td.
1. Gidi thieu
Hidn nay, van dd d nhiem mdi trudng da trd t h i n h mdi quan lam ciia mpi qudc gia tren ihd gidi. Vide g i i m thieu khf t h i l ddc hai, d i e bidt la SO, va CO, la van de sdng edn de d i m b i o p h i t trien ben vdng. Vi vay, song song vdi vide nang cao hieu suit l i m vide ciia dpng co thi viee si/ dung nhidn lieu saeh ngay cang dupc quan t i m . H i m lupng lUu huynh trong x i n g n g i y cang bi han chd [1,21.
Phuong phap truydn thdng de loai luu huynh trong xang l i sddyng qua trinh hydrodesunfua hda. Hidn nay, phuang p h i p n i y v i n dupe sd dung pho bien trong h i u het cac nha m i y loc d i u trdn the gidi. NhUng phuong phap nay ydu cau p h i i tien hanh d didu kidn khie nghidt, i p suit va nhiet do cao (300 - 340°C, 20 -10Oatm). Thdm v i o dd, de giam s i u ham lupng lUu huynh (xudng dudi 1 Sppmw/) the tich thiet bj p h i n dng v i lupng chit xiic t i c sir dyng p h i i tang len nhidu l i n mdi cd the dat duoc ydu c i u [3]. Dong thdi, loai sau lUu huynh b i n g phuong p h i p n i y doi dien vdi nguy cO l i m g i i m trj sd octane ciia xang.
Vl vay, vide tim giai p h i p thich hop de loai sau lUu huynh v i khdng l i m g i i m trj sd octane ciia xing, ddng thdi cd tinh k h i thi dang la dd t i i duoc nhieu n h i khoa hpc iren the gidi quan tam nghien cdu. Tuy nhidn, phuong p h i p truyen thdng van rat cd g i i trj, d i e biet trong vide loai so bp luu huynh trUdc khi tien h i n h loai siu luu huynh trong xang b i n g cac phuang phap khic.
Sd dyng c h i t hap phu de loai s i u luu huynh la hudng di mdi rat cd tiem n i n g do qua trinh thyc hidn d didu kien thudng [4, 5] nhung p h i i tim ra duac c h i t h i p phu thich hop. Trong nghidn cdu niy, nhdm t i c g i i tidn hinh tong hap ehit h i p phu NiX di t d NaX b i n g p h U O i ^ h a p trao doi ion. Hidu q u i qua trinh hap phu, i n h huong cua bin chit hpp ehit chda luu huynh tdi q u i trinh h i p phu, mo hinh q u i trinh hap phy duoc nghidn cdu.
2. ThiTc nghiem
NaX zeolit dupc cung c i p bdi Vien D i u mo Phap (Institut Franijais du Pdtrole, IFP, France). Ni{NOj), (99%) l i sin p h i m ciia Cdng ty Carlo Erba. 3-meihylthiophene (3-MT, C^H^S, 99%) va benzothiophene (BT, C^H^S, 97%) dupe mua cua Cdng ty Acros Organies (New/ Jersey, USA).
Iso-octane (C^H,^, 99,5%) l i sin pham cua Famitalia Carlo Erba (Milan, Italy).
Q u i trinh tdng hpp NiX tir NaX b i n g phUdng phip trao ddi ion dupe md t i tdm t i t trong Hinh 1.
Didn tfch be mat v i kich thUde mao quin cua chit h i p phy duac p h i n tich b i n g phuang p h i p hap phu/
d i i h i p phu nito sir dung thiet bj SAA (Themo Finnigan, Sorptomatic model). Nhidu xa tia X (X-ray diffraction, XRD) duoc tidn h i n h trdn m i y Rigaku, Rint 2200 HV LUpng kim loai trdn zeolit ddpc p h i n ti'ch b i n g phdcmg phip pW h i p thu nguydn tir (Atomic Absorption Spectrometer- AAS) sir dyng m i y Varian, SpectrAA 300.
38 iUKHl-Sdl1/2D12
PETROVIETNAM
Q u i trinh hap phy dupe thyc hien trong Ip nhd, vial, {15cm').Ty Id nhien lieu: chat hap phy l i 8516] dUpc khuay lien tyc trong 8 gid [7]. Khi he dat c i n b i n g , m i u dUpe liy ra v i phan tfch b i n g m i y sic khf (HP 5890 Series 2) si/
dung detector ion hda ngon Ida (FID detector) v i cdt HP-5 (30cm X 0,32mm x 0,25mm).
3. Ket q u i va thao luin
3.1. Tong hpp vd phdn tich dac trUng mdu chdt hdp phu Qua trinh trao doi ion d pha Idng khdng ehl bj gidi han bdi cin b i n g nhiet ddng lUc hoc m i cdn bdi ydu td khdng gian do sU hinh t h i n h q u i trinh solvat hda ciia cac cation ed the trao ddi trong mdi trUdng
nude. Mpt trong nhdng phuong phap hieu q u i de khie phue v i n dd niy la tang nhidt do trong qua trinh trao ddi ion. Trong nghien cdu nay, nhiet do qua trinh trao ddi ion duac thay ddi tir 30 - 90*^. 6 mdi nhidt dd, nhdm t i c g i i tidn h i n h thi nghidm 3 lin. Ket qua do AAS the hien tren Hinh 2.
Hinh 2 cho t h i y lUOng Ni trdn zeolit t i n g khi t i n g nhiet dp q u i trinh trao doi ion. Nhiet do tang l i m ting tdc dp khueeh t i n eua ion kim loai tdi mao quan cua zeolit. Ngoai ra, tang nhiet do eung thuc day q u i trinh dehydration do c i u true zeolit dao dpng manh hPn.Tuy nhidn, t i n g nhiet dp cung cd the gay ra hien tuong p h i vd cau true zeolit, dae bidt vdi zeolit NaX do zeolit n i y ed tinh ben nhiet kem [8]. Vi vay, nhdm tic g i i d i tien hanh phan tfch nhieu xa tia X va do dien tich bd mat bang phuong phip hap phu v i t ly (BET) CLia cae mau trudc v i sau khi tien hinh trao doi ion.
Theo ket qua d Bing 1, khi nhidt dp ciia q u i trinh trao doi ion d eo^C va 90''C didn tieh bd m i l ciia m i u NiX giim dot ngpt. Ket hop vdi ket qui phin tich nhieu xa tia X ciia cic mau niy (Hinh 3), nhdm t i c g i i nhan thay cd sU p h i vd c i u true ciia zeolit.
Trong khi dd, d 45''C, kdt q u i p h i n
tfch nhieu xa tia X trong Hinh 3 cho thay cau true zeolit duoc b i o toan. Oidu n i y cung hoan toan phii hop vdi ket q u i p h i n tfch dien tfch be mat. Khi tien hanh trao doi ion d 45''C, dien tfch be m i l cua mau NiX thu dUpe g i i m khdng d i n g kd so vdi NaX.
Can cir v i o cic kdt q u i trdn, mau v i t lidu NiX thu duoe khi tidn h i n h trao ddi ion d45''Cduac lUa chpn cho nghien ciru trong b i i b i o niy. Kdt q u i phan tich c i u true ciia eic m i u chat h i p phu sddung phuong p h i p h i p phu v i t ly dupc trinh bay trong Bing 2.
Tu kdt q u i thyc nghiem tdng hop trong Bing 2 va 3 eho thay. mau NiX ed the tieh mao q u i n nhd hpn nhidu
Hinh 1. Sadd qua trinh tong hap mdu chdt hdp phu bdng phuang phdp trao ddi Ic
&
s 1 M : • i ^-
[ O l i n l D L i n 2 A l i n 3
30 35 40 45 50 55 60 65 70 75 80 K Nhi$t dp (OC)
H i n h 2. Anh hudng cua nhiit do tdi hdm luang kim loai trao doi ic
tiang !. Kcl qtia jiiKin iici^ diin ticll W m(if Dl^nt(chb4m$t
(BET, m"/gl 639 527 512 2S4 , nhidt dd t6n
NaX NiX. BCC NiX, 45T NiX, ecc NiX. gcc
ghflfp
2-thMa-Kal*
u
so vdi NaX. Ni cd kich thUdc Idn han Na ndn trong mao q u i n ciia zeolit, Ni chidm nhidu khdng gian hon, do 66 l i m g i i m thd tich mao q u i n ciia m i u .
3.2. Hdp phu topi luu huynh trang xdng Theo nhidu nghidn ciru, cic c h i t chda luu hwyrh trong x i n g thUdng l i cic hpp c h i t ciia ihiophen, di^n hinh l i 3-meihylthlophene (3-MT) v i Benzothiophene
(BT). Ddng thdi, vide sii' dyng iso-octane l i m c i u t d dd md phdng x i n g trong qui trinh thi nghidm cung dupc sif dung rdng r i i [3, 4, 9, 10]. Chinh vi viy, chiing tdi sil dyng 3-MT trong iso-octane v i BT trong iso-octane l i m nguydn tidu dd nghidn ahi k h i n i n g h i p phy chpn loc luu huynh cfla NiX. H i m lupng lUu huynh trong nguySn lidu dupc thay ddi t d 500 - 2.5O0ppmw.
D4 d i n h g i i k h i nang h i p phu liiu huynh trong x i n g cua NiX eung nhUinh hudng cua h i m luong Ni tdi k h i ning hip phy luu huynh, 3 m i u NiX c6 h i m lupng Ni k h i c nhau dupe tdng hop. DUa vio ket q u i thi nghidm tifng m i u , nhdm tic gia da tidn hanh x i y dung ducmg d i n g nhiet h i p phu 3-MT v i BT trong iso-octane cua cic mSu NiX vdi h i m lupng Ni khac nhau dua vao lupng luu huynh hip phu v i ndng dp c i n b i n g (ndng dd luu huynh trong nhien lieu khi he dat trang thii can bing).
Didu thil VI l i dudng d i n g nhidt hip phy cua c i 3-MT va BT trong iso-octane ddu khdp vdi dudng d i n g nhiet hip phy Langmuir md t i qua trinh h i p phy don Idp. Phuang trinh dUdng d i n g nhidt hap
(b)
i?ui4^'U
phy Langmuir tUcfng dng l i [9,11]:
(1)
2-th«ta sale
Hinh 4. Kit qud phan tich nhiiu xa tia X. (a) NaX vd (b) NiX (7,48%wt Ni) tong hap tgi 45°C 40 DAUKHl-Sdl1/2012
l + bC^
Hoic dudi dang:
^ - f ^ , _ l _ (2) Qs °^ °™ "
Trong id: Q, vS Q „ „ lan luot IS lUOT lau huynh hSp phu (mmol-S/g - ch^t hSp phu) v^ luong lau huynh hap phu t6i da (mmol-S/g - chSt hSp phu); q IS n6ng « can bSng (mmol-S/g - xang); b IS hSngso h^p phu luu hujfnh (g-xang/mmol-S).
PETROVIETNAM
Tir phuang trinh (2) cd the xac djnh duoc cac g i i tri b va Q^^^ b i n g phUOng phap binh phuong ciic tidu gida C/Q^ va Cj. Ket q u i thu 6^igc dupc tdng hop trong Bing 3va4.
Trong trudng hpp hap phu 3-MT (Hinh 7), cd the t h i y mac dii m i u 5,22%kl NiX ed ham lupng Ni cao hOn so vdi m i u 2,61 %kl NiX nhung khi nang hap phu 3-MT lai thap hpn, m i u 7,48%kl NiX cd k h i nang h i p phy eao nhit. Nhu Sau khi xic dmh dupc g i i tri eiia Q„3,va
b nhu trong Bing 3 va 4, nhdm t i c g i i tidn hanh xay dUng dudng d i n g nhiet h i p phu 3-MT v i BT trong iso-octane ciia cic m i u vat lieu dya v i o cic gia tri Q^^^va b vi/a tim dUpc.
De so sinh k h i n i n g hap phu lUu huynh cua m i u NiX vdi mau NaX c i n xet tren cung mpt don vj the tich mao q u i n . Ket q u i tinh toin xac dinh lUong lUu huynh hap phy tren mpt dPn vi the tieh mao q u i n chi't h i p phu sir dung the tfch Vp - Dubinin trong Bing 2 dupe the hien tren Hinh 5 va 6. Rd ring, trdn cung mdt dPn vi the tfch, ddi vdi c i 3-MT va BT, NiX ed k h i nang h i p phy tdi da cao hpn (Q^J so vdi NaX. Dieu niy ed the duoc ly giai bdi sU hinh thanh phdc n gida Ni'^ va luu huynh [9] do Na"" khdng cd k h i n i n g tao thanh phdc n vdi luu huynh.
Hinh 5 cho t h i y NaX ed kha nang h i p phy 3-MT tot hon so vdi NiX mac dii Q^^__ ciia NaX nhd hon Q__^^ciia NiX. Trong trUdng hop nay anh hudng ciia yeu td khdng gian ciia vat lieu hap phu ddng vai trd quan trong hon i i lue hap phy do kfch thudc phan tir eiia 3-MT nhd Khi dien tfch be mat g i i m , ddi vdi mau NiX, kha nang tiep can eua 3-MT tdi t i m hap phu giim di nen lam giam khi nang hap phu.
NgUPc lai, ket q u i tren Hinh 6 cho thay NiX ed kha ning hap phu BT tot hon so vdi NaX. BT ed kich thudc phan t d Idn nen kha nang tiep can tdi t i m hap phu eiia chung g i i m do i n h hudng ciia yeu td khdng gian. Trong trUdng hpp nay, vai trd ciia i i lUc h i p phu tang len dan ldi NiX ed kha nang hap phy BT tdt hon NaX. Khi ndng dp BT cang t i n g c i n g t h i y rd vai trd ciia ai lye h i p phu, k h i n i n g h i p phu ciia NiX tot hon nhieu so vdi NaX.
Hinh 7 va 8 eho t h i y lUPng lUu huynh hap phu trdn cie mau NiX cd h i m lUpng Ni khac nhau khdng cd nhidu sU khac biet ve hinh dang nhung trong pham vi khio sit, lUpng Ni tren chat hap phy ddng vai trdquan trpng den khi ning hap phu hop chit chda luu huynh.
Bdng 2. Kit qud do hdp phu vdt ly Tinh chSt NaX NiX (7,48%wt Ni) Didn tich bd mSt (mVg) 619 512 VM{t-plot)(cmVg) 0,235 0,086 VM {Dubinin) (cmVg) 0,249 0,139 ^ Bdng 3. Hi s6 cua phuang trinh dddng ddng nhiet hdp phu Langmuir 3-MT
trong iso-octane
Chilit h i p p h u
NaX NiX(2.61%vrtNi) NiX (5,22%wt Ni) NiX (7,48%vrt Ni)
Bdng 4. He SO cua
C h a t h a p p h u NaX N i X ( 2 , 6 1 % w t N i ) NiX(5,22%wrtNi) NlX(7,48%wrtNi)
( m m o l - S / g - c h i t h i p p h u ) 1,6998 1,6866 1,7467 1,7768
b ( g - x i n g / m m o l - S )
0,0468 0,0474 0,0419 I 0,0416
phuang trinh dudng ddng nhiet hdp phu Langmuir BT trong iso-octane
( m m o l - S / g - c h a t h a p p h u ) 0,9088 1,0705 1,0641 1,0746
( g - x a n g / m m o l - S ) 0,9334 j 0,5070 I 0,5623 0.6044
O.S
0.7 f O.e
1 "•'
f "
t 0.3 d
0.2 0.1
MTtrong tao^cnn* ^
^ j ^ f r
^ ^ - t - N ^ X
y ^ ^"-NlXlMaiHimD
S 10 15 ! C|()iino1-8'g-Kiing)
0 Hinh S. DUdng dang nhiet hdp phu 3-MT trong iso-octane
C|(mnK>l-«/g->ing) Hinh 6. fiiiai'g (Idnq niiicl hnp phu BT Irong iso-octane
OB 0.7 1
1 "
*
M 0 5 ^ f 0 4 -
£ 0.3 -
0,2 ' j ^
0 1 - / 0 ^ —
0
A ^ - • - N [ X ( 2 a i l i k l N 0
- • - N i X (5,22 %lilNi)
— NIX (7,48 Mil Nf)
5 10 15
C( (mmol^g • Xing} 20
H i n h 7. Oudng ddng nhiet hdp phu 3-MT trong iso-octane
Cs<mmol-8/g.)iing) Hinh 8. Dudng ddng nhiet hdp phu BT trong iso-octane
p h i n tich d trdn, d6i vdi q u i trinh h i p phu 3-MT, do kfch thudc nhd cua 3-MT ndn inh hudng ciia ydu td khdng gian ciia vat li^u h i p phy trong mdt gidi han n h i t djnh dd/ig vai trd quan trpng hon ydu td i i lUc h i p phi^
cCia v i t lidu h i p phy. d m i u 5,22%kl NiX, sir p h i n bd Ni d vj trf thich hpp dd 3-MT tidp xiic duoc trong q u i trinh h i p phy t h i p hpn mau 2,61%kl NiX. Tuy nhidn, phuong phip hip phu hda hpc dOng CO hoic H^ khdng ly giii dupe g i i thuydt thir hai do c i CO v i H^ ddu cd kich thudc p h i n tir nhd hon 3-MT ndn CO.
{ v i H^) cd thd "nhin t h i y ' c i c Ni d c i c vj trf r i # 3-MT khdng thd (vl viy, dd g i i i thfch cu thi hidn tupng n i y c i n nghidn cdu siu hon).Bii vdi q u i trinh h i p phu BT (Hinh 8), khi nang h i p phy l i n g d i n vdi h i m lUOng Ni. Vdi BT, do kfch thudc p h i n tir Idn ndn i i lUc h i p phu ddng vai trd quan trong trong q u i trinh hap phy BT Idn NiX, vi v i y k h i n i n g h i p phu BT tang vdi h i m lupng Ni
Hinh 9 md t i i n h hudng ciia ciu tnjc p h i n t d c h i t chda luu huynh tdi khi nang hap phu cua NiX (7,48%wt Ni). Rd ring, eac cau tir khac nhau cd k h i nang h i p phu len NiX (7,48%wt) khic nhau. Do kieh thUdc p h i n t d cua 3-MT nhd hon BT ndn khi hap phu len NiX (7,48%vrt), 3-MT cd Q ^ Idn hon rat nhidu so vdi BT, khoing 1,6 lin (Bing 3 va 4). Tuy nhien, d viing nong dd cin bing t h i p , dudng d i n g nhidt h i p phu BT trdn NiX (7,48%wl) ddc hon so vdi dudng ding nhiet h i p phy ciia 3-MT trdn NiX (7,48%wl}. Nhi/
viy, i i lye h i p phu len NiX (7,48%wt) ciia BT cao hon nhidu so vdi 3-MT. Oidu niy dupe ly g i i i bdi cau true p h i n t d eiia BT gdm 2 vong thom ndn cd mat dp electron eao hOn so v6i 3-MT (cd 1 vdng thom). Do viy, BT cd khS nang tao phdc n vdi Ni trong c i u triic zeoiit tdt hon so vdi 3-MT.
4. Ket luSn
Qua nghien cOru niy, nhdm t i e g i i rut ra mdtso kdt l u i n sau:
- Da tdng hop t h i n h cdng NiX tC/ NaX co didn tich be mat Idn v i cd k h i n i n g h i p phu lau huynh tdt;
4 2 DAU KHl-SO 11/2012
PETROVIETNAM
CiimmoWg-mngl
Hinh 9. Dudng ddng nhiit hdp phu cua NiX zeolit (7.48%wt Ni}vdi cdc cdu td chUa liiu huynh khdc nhdu tmng iso-octane
Qui trinh hap phu 3-MT v i BT trong iso-octane len NiX (2,61; 5,22 v i 7,48%vrt) va NaX tuan theo quy luit h i p phu Langmuir don Idp;
Vdi eiing mot dPn vj the tfch mao q u i n , NiX cd khi ning hap phu luu huynh tdi da tdt hpn nhieu so vdi NaX do su hinh t h i n h eua phdc n gida luu huynh va Ni^*;
Ham lupng luu huynh anh hUdng ro tdi kha nang hap phu, die bidt trong trudng hop h i p phu BT, k h i n i n g hap phu tang d i n vdi su tang ham lUong kim loai tren mau NiX;
Ciu true p h i n t d c h i t chda lUu huynh i n h hudng manh tdi k h i nang h i p phy lUu huynh ciia mau NiX (7,48%wt). Lupng luu huynh bj h i p phu tdi da {mmol-S/g- chit hap phu) eiia 3-MT Idn ban so vdi BT do cd kieh thUde phin tir nho hpn. Tuy nhien, d viing ndng dd c i n b i n g thip BT cd ai lue hap phu vdi NiX Idn hon 3-MT do c i u true phan tdcd mat dp electron eao hon.
Tai lieu tham khio
1. A.J.Hernandez-Maldonado and R.T.Yang.
Desulfurization of commercial liquid fuels by selective adsorption via n-complexation with Cu(l) - Y zeolites.
Industrial & Engineering Chemistry Reserch. 2003; 42: p.
3103-3110.
!. I.V.Babieh and J.A.Moulijn. 5e/ence and technology of novel processes for deep desulfurization of oil refinery streams: a review-Fuel. 2003; 82; p. 607 - 631.
3. X.Ma, S.Velu, J.H.Kim and CSong. Deep desulfurization of gasoline by selective adsorption over
solid adsorbents and impact of analytical methods on ppm-level sulfur quantification for fuel cell applications.
Applied Catalysis B: Environmental.
2005; 56: p. 137-147.
4. X.Ma, L.Sun and C.Song. A new approach to deep desulfurization of gasoline, diesel fuel and jet fuel by selective adsorption for ultra-clean fuels and for fuel cell applications. Catalysis Today. 2002; 77; p. 107-116.
5. X.Ma and C.Song. New design approaches to ultra-clean diesel fuels by deep desulfurization and deep dearomatization. Applied Catalysis B;
Environmental, 2002; 41: p. 207 - 238.
6. J.Chansa. Removal of sulfur compounds from transportation fuels by adsorption. The Petroleum and Petrochemical College, Chulalongkorn University, Thailand. 2004.
7. S.Pringprayong. Adsorptive removal of sulfur compounds from transportation fuels using zeolitic adsorbents. The Petroleum and Petrochemical College, Chulalongkorn University, Thailand. 2006.
8 S.M.Auerbacn, K.A.Carrado, RK. Dutta. Handbook of Zeolite ^Science and Technology, hiew York: Marcel Dekker. 2003.
9. AJ.Hernandez-Maldonado, F.H.Yang, G.Qi and R.T.Yang. Desulfurization of transportation fuels by n-complexation sorbents: Cud)-, Ni(ll)-, and Zn(ll)-zeotites.
Applied Catalysis B: Environmental. 2005; 56, p. 111 -126.
10. V.M.Bhandari, C.H.Ko, J.G.Park, S.S.Han, S.H.Cho and J.N.Kim. Desulfurization of diesel using ion-exchanged zeolites. Chemical Engineering Science. 2006; 61: p.
2599 - 2608.
11. A.Chicaa, K.Strohmaier and E.lgiesia. Adsorption, desorption, and conversion of thiophene on H-ZSM5.
Langmuir. 2004; 20: p. 10982 -10991.
