TAP CHI HOA HOC T. 51(1)28-31 THANG2NAM20I3
NGHIEN CU'U P H A N UNG 06NG PHAN HOA W-PARAFIN NHE SU' DUNG C H A T L 6 N G ION DANG TRIETYL AMIN HYDROCLORUA
LAM CHAT XUC TAC
Biii Thj Lf Thuy
Trudng Dgi hgc Md Dja chdt. Ddng Nggc. Tu Liem, Hd Ngi Den Tda soan 31 -5-2012
Abstract
Isomerisation of/j-hexane and mixture of M-hexane and «-pentane was performed in a batch reactor using the pure ionic liquid trielhyl amine hydrochloride-aluininium chloride (C2Hj)3NHCi/AlCl3), and a mixture of this ionic liquid with a transition metal salt. The reaction was carried out smoothly in liquid phase under atmosphere pressure. The acidity of ionic liquid was modified by the addition of CuCI. The substrate conversion 25% and research octane number 89 were observed by using (C2Hj)3NHCl/AlCl3 (molar fraction of AICI3 is 0.64) in the present of CuCI at lO^Covera period of 1 hours. The products were separated simply by decantalion, and thus the catalyst can be reused. Moreover, the formation of heavy hydrocarbons is minimised.
Keywords: ionic liquids, isomerization, ^-paraffin 1. MCJ D A U
Phan ling ddng phan hoa «-parafin thanh cac isoparafin dugc thyc hien trong cdng nghiep de san xuat xang dgng ca cd chi sd octan cao. Xuc tac di the cho phan irng nay la he xiic tac ludng chuc, kim loai mang tren cac oxit hdn hgp, zeolit, axit ran, oxit da sunfat hoa va mgt sd he khac [1],
Nhugc diem chung cua cac xiic tac dj the la phai thirc hien phan irng d nhiet do kha cao (thudng la tren 120°C), dieu nay khdng thuan lgi ve nhiet ddng hgc. Ngoai ra cdn phai diing hydro de ngan chan phan irng phu va tang dd ben ciia xiic tac (vi du ban che su tao coc) [2]. Nhieu nghien cuu dugc thyc hien de cai thien hoac tim ra he xiic tac mdi cho phan ung nay. Trong sd dd chat xiic tac di tir chat long ion dang dugc quan lam.
Tren the gidi da cd mgt vai nghien ciru sir dyng chat long ion (IL) iam xiic tac cho phan irng nay va cho ket qua kha quan [3]. Trong cdng trinh trudc chiing tdi da nghien ciru su dung chat long ion dang pyridin lam chat xiic tac [4]. Trong nghien ciru nay chiing tdi thuc hi?n phan iirng ddng phan hda n-parafin sir dung chat xiic tac la chat Idng ion (C2H5)3NHC1/A1C13 (trietyl amin hydroclorua-nhdm clorua).
2. THI/C NGHIEM
Tdng hop (CiH5)3NHCI/AICl3
Cho (C2H5)3NHCI vao binh ba cd cd lap may khuay va nhiet ke de dieu chinh nhi?t dg. Vi phan irng tda nhiet nen binh phan ung dugc lam lanh bang nudc da. Sau do vira cho AICI3 vao vira khuay. Sau khi cho het AICI3 vao thi khuay them 2 gid rdi bo binh each thiiy ra de nhiet dg cua binh phan irng tang den nhiet dg phdng rdi khuay them 6 gid nCra. Chat long ion tong hgp dugc dem do phd hdng ngoai vdi chi thi pyridin de xac djnh tinh axit.
Tong hgp (C2H5)jNHCl/AlCl3/CuCl: Phuang phap tien hanh tuong ty nhu tdng hcq) (CiHsJjNHCl/AlCb. Sau khi cho hit AlCb thi cho CuCI vao, lugng CuCI cho vao khoang 1,7% moi tinh theo lugng AICI3.
Phan trng dong phan hda voi xuc tac la chat long ion
Cho chat ldng ion va »-hexan (hoac hdn hgp /(-hexan vdi H-pentan) vao binh 3 cd cd lip may khuay, sinh ban hdi luu va nhiet kl. Sau dd khuay va giii- d nhi?t dg yeu cau bang nudc da trong suit qua trinh phan irng. San phim thu dugc la chit long khdng mau va dugc phan tich sac ky khi-khdi pho de xac djnh thanh phan. Cac chi tieu dugc diing de daiih gia hi?u qua cua chat xuc tac la thanh phan san pham, chi so octan nghien cuu tinh theo ly thuylt (RON) cLia san pham va dg chuyin hda cua phan ung ddng phan hda. RON dugc ti'nh theo cdng thurc sau (y,: phan khdi lugng ciia clu tir i, RON,: chi s6 octan nghien ciru ciia clu tu i).
TCHH, T. 51(1), 2013 RON = ^y^RON,
1=1
3. KET QUA v A T H A O LUAN 3.1. Tinh axit
Tinh axit cua [CsHsNHJCl/AICb va (CjHOjNHCl/AlCb phy thudc vao phan moi cua AICI3 trong [CsHsNHJCl/AlClj ho$c (CzHsJjNHCI/AICb. Phan moi ciia AICI3 dugc xac djnh bdi cdng thirc:
X = moi AlCl3/(mol AICI3 + mol IL) Cac chat Idng ion cd phan mol ciia AICI3 nam trong khoang 0 < x < 0,5 dugc ggi la cac chat Idng ion baza, chung khdng xiic tac cho phan irng ddng phan hda. Trong khi do cac chit long ion cd phin mol X > 0,5 dugc ggi la cac axit Lewis, chiing cd tinh axit va xuc tac cho phan irng ddng phan hda.
Phan mol x cang ldn thi tinh axit cang manh. Tinh axit cd the dieu chinh dugc bang each thay ddi thanh phan chat ldng ion, tinh chat nay la mgt lgi the ciia chat Idng ion.
Trong nghien ciru nay, tinh axit ciia cac chat Idng ion (C2H5)3NHCI/AlCl3 cd thanh phin khac nhau dugc xac djnh vdi chat chi thj pyridin. Ket qua dugc dua ra d hinh 1.
Bill Thi L? Thuy phep ta thay doi tinh axit ciia chiing de phii hgp vdi tirng phan iing cy the.
Cac dinh nhd xuat hi?n d khoang 1536 cm"' dac trung cho lien ket N ciia vdng piridin va H* cho thay sy cd m^t ciia cac tam axit Brdnsted. Cac axit nay tgo thanh do sy cd mat ciia nudc trong qua trinh tdng hgp chat Idng ion theo phuang trinh phan ung:
AICI3 + H2O -> AICI3OH' + H^
H* + AlCl3-> HAICI-,.
3.2. Anh hirdng cua tinh axit ciia chat long ion den phan irng dong phan hda
Nhu da chi ra trong [4] tinh axit cua xiic tac la yeu td quan trgng. Cac thi nghiem dugc tien hanh vdi cac chat Idng ion (C2H;)3NHCI/AICl3 cd phin mol ciia AICI3 khac nhau de tim ra chat ldng ion cd thanh phan toi uu. Phan mol dugc khao sat nam trong khoang 0,55 den 0,67 (hinh 2).
1500 1460 Wave number {cn>1)
Hinh I: Phd FT-IR ciia hdn hgp pyridin va (C2H5)3NHC1/A1CI3 vdi: (a) phin mol ciia AICI3 X = 0,565, (b) X = 0,60, (c) x = 0,63, (d) x = 0,655
Sy cd mat ciia cac dinh d gan 1450 cm"' dac trung cho lien kit ciia nguyen tiJ Al ciia AICI3 va N cua vdng pyridin (chit chi thj) cho thIy cac chit Idng ion la cac axit Lewis m?nh. Khi tang phan mol ciia AICI3 thi cac dinh djch chuyin nhieu ban vl phia budc sdng ngin, dieu nay phii hgp vdi ly thuylt: tinh axit cua chit ldng ion phu thudc vao phan mol cua AICI3 (ham Iugng AICI3 trong IL).
Chinh uu dilm nay cua chit long ion cd thi cho
0,57 0,60 0,63 Phin mol AICI3
Hinh 2: Anh hudng ciia tinh axit ciia chat ldng ion den phan iing ddng phan hda o-hexan vdi xiic tac (C2H5)3NHCI/AICl3(10°C, 1 gid, ti le thi tich n-hexan/IL= 0,4), iso Ct: hydrocacbon CgHu mach
phan nhanh, Ce vdng: C6H14 mach vdng, C7+; hydrocacbon tir C7 trd len Tir cac sd li?u ta thay, ti'nh axit cua chat ldng ion anh hudng den thanh phin san pham va dg chuyen hda ciia phan irng ddng phan hda «-hexan. Ham lugng cac chit vdng tang nh? den khi phan mol cCia AICI3 dat 0,64 thi giam. Khi tang phin mol ciia AICI3, ddng thdi vdi viec tang t6c dg phan ung (dan
TCHH, T.51(l), 2013
din tang Iugng san phim Q vdng) thi ndng dg ion H* (ion nay cd sin trong chit ldng ion) cung tang va thuc diy cho phan iing dong phan hda nhdm metyl.
Do dd, khi phin mol ciia AICI3 dat din 0,67 thi ham lugng ciia cac hydrocacbon CftHn mach phan nhanh (iso Co) l?i tang nh?. Ham lugng khi va cac san pham nh? cQng tang khi phin mol ciia AICI3 tSng.
Dg chuyin hda ciia /i-hexan tang m^inh lir 16%
den 25% khi phin mol ciia AICI3 tang tir 0,55 den 0,67 cho thay kha nang phan irng ciia parafin clang phy thugc vao tinh axit ciia chit ldng ion. RON ciia san pham d^t eye dai khi phin mol ciia AICI3 dgt 0,64. Mgt khac, khi dg chuyen hda tang thi lugng san pham nh? cung tang. Vi v^y, luang ty nhu trudng hgp [CsHiNHJCI/AICb, trong cac nghien ciru tiep theo chung tdi sir dyng chit ldng ion cd phan molcuaAICl3la0,64.
3.3. Anh hudng cua nhi^t dg phan ung Phan ling ddng phan hda la phan ung tda nhiet nen nhipl dg cao khdng thuan lgi cho phan irng ve mat nhi^t dgng hgc. Tuy nhien, nhiet dg thap lai lam giam toe dg ciia phan ung. Ngoai ra, khi lang nhiet do cdn lam thay ddi can bang nhiet ddng hgc ciia cac san pham. Do do, viec lua chgn nhiet dd phan irng cho tirng loai xiic tac cu the la rat quan trgng. Day cac thi nghiem dugc thyc hien d cac nhiet do thay ddi (tir 0°C din 30°C) trong khi cac dieu kien khac giircd dinh. Ket qua dugc trinh bay dhinh 3.
Trong khoang nhiet do khao sat, thanh phan san pham it bi anh hudng bdi nhiet do. Khi tang nhiet dd thi ham lugng cac san pham da phan nhanh nhu 2,2- dimetylbulan giam trong khi 2- va 3-metylpenlan lai tang. Ti le cac san pham vdng metyl-xiclopentan va xiclohexan cung thay ddi, Ti sd ham lugng metyl- xiclopentan/xiclohexan tang. Thanh phan cac san pham nhe va nang it thay ddi vdi nhiet dg trong khoang khao sat.
Do chuyen hda tang nhe va chi sd octan giam nhe. Do dieu ki?n thi nghiem chi thyc hien dugc d pha Idng nen chiing tdi chua nghien ciru phan irng nay d viing nhiet dg cao hem.
3.4. Anh hudng ciia phu gia CuCI toi hoat tinh cua (CjHOsNHCl/AlCIj
6 phan nay chit long ion AlCl3/(C2H5)3NHCI dugc trgn them CuCI vdi ty le 1,7% mol tinh theo lugng AICI3. CuCI dugc chgn Iam phy gia bdi vi theo ket qua cua mgt sd nghien ciru thi AICI3 tinh khiet khdng xiic tac cho phan irng ddng phan hda [5]
nhung hdn hgp AICI3 va CuCI lai xiic tac cho phan ung nay. Kit qua dugc dua ra trong bang I.
Nghien ciru phdn ung ddng phdn hoa...
.%
1 .s
Q .
Than
sn
40 30 20 10 0
-C^vong
0 10 20 Nhiet d^phan irng, "C
80 60 40 20
„
|—0— Do chuyen hoai l-O-RON 1
Nhiet do phan irng, "C
Hinh 3: Anh hudng ciia nhiet dd den phan iing ddng phan hda w-hexan vdi xiic tac (C2H5)3NHC1/AICI3 (1 gid ; ti 1| the tich ?/-hexan/IL= 0,4; phan mol ciia
AlCl3-0,64)
Bdng 1: Anh hudng ciia chat phu gia CuCI den phan ung dong phan hda «-hexan vdi xiic tac (C2Hs)3NHCl/AICl3 (1 gid; ti le thi tich «-hexan/IL=
0,4; phan mol ciia AICI3 = 0,64; ham Iugng CuCi la l,7%moI so vdi (C2Hs)jNHCl/AlCl3) Xiic lac
Th^nh phan san pham, (%kl) khi isopentan 2,2 dimetylbutan 2-metylpentan 3-metylpentan metyl-xiclopentan xiclohexan
c„
Bp chuyin h6a (C%) RON
(CHsjjNHC 1/AlCl,
6,1 3,8 6,2 23,7 19,9 32,3 6,4 1,6 21 88,3
(C,H5),NHC1/
AlCl, + CuCI
7,5 4,2 7,2 20,9 19,1 33,9 5,6 1,6 25 89,0 Ket qua cho thIy khi them CuCI thi dg chuyen hda ciia n-hexan tang tir 21% den 25%, chi so octan tang nh? tir 88,3 den 89. Thanh phin san pham it
30
TCHH, T. 51(1), 2013
thay ddi khi cd mat chit phy gia. Do chuyin hda tang dugc giai thich la tinh axit ciia IL tang len khi cho CuCI vao [7]. Ngudi ta da lien hanh do tinh axit ciia AlClj va hdn hgp AICI3 vdi CuCI. Cac gia tri H^
thu dugc tuang irng la -13,75 va -14,52 [7].
3.5. Anh hirdng cija chat khoi mao
Phan ling ddng phan hda xay ra theo ca che cacbocation trung gian nSn cac hgp chat de tgo thanh cation dugc xem la xiic lien cho phan irng nay.
Trong mdt sd tai It^u [6], H-butanol, /-bulen, i-pentan, /-butan dugc sir dung iam chat khai mao cho phan ung va trong mgt sd trudng hgp da lam lang dp chuyen hda. Trong thi nghiem nay, isoamyl ancol dugc trgn lan vdi H-hexan trudc khi cho phan irng vdi sy cd mat ciia xiic tac chat long ion. Ket qua thu dugc dugc dua ra trong bang 2.
Bdng 2: Anh hudng ciia chat khai mao din phan irng ddng phan hda n-hexan vdi xiic lac (C2H5)3NHC1/A1C13 (1 gid; ti le thi tich
;i-hexan/IL= 0,4; phan mol ciia AICI3 = 0,64; li le the tich ciia rugu i-CsHnOH/o-hexan = 0,2)
Xiic tac Thanh phan san pham, (%kl) khi isopentan 2,2-dimetyibutan 2-metylpentan 3-metylpentan metyl-xiclopentan xiclohexan c^+
Do chuyen hoa (C%)
RON
(CjHsjjNHCI/
AlCb
6,1 3,8 6,2 23,7 19,9 32,3 6,4 1,6 21 88,3
(CiHj)jNHCl/
A1C1,+
C,H,iOH
9,1 4,1 7,1 20,5 18,8 30,8 5,5 4,0 30 88,8
Bui Thi L? Thiiy phan irng vdi hdn hgp n-pentan va «-hexan vdi ty Ie thi tich 35/65 (bang 3). _
So sanh phan irng ddng phan hda n-hexan va hdn hgp n-pentan va n-hexan ta thay, phan irng ddng phan hda hdn hgp eho do chuyen hda thap hon do n-pentan khd chuyen hda han. Ham lugng khi va isopentan tang len do cd mat n-pentan va do dd chi sd octan cung tang len.
4. KET LUAN
Chat Idng ion [CsHsNHJCI/AICb long hgp dugc cd boat tinh xiic tac cho phan irng ddng phan hoa /^-parafin.
Thanh phan ciia chat Idng ion cd anh hudng quyet dinh den hi?u suat va chat lugng san pham ddng phan hda trong khi nhiet do lai it anh hudng trong viing khao sat. Hoat tinh xiic lac ciia chat Idng ion cao nhat khi: phan mol ciia AICI3 = 0,64 va nhiet dg phan ung la 10"C.
Bdng 3- Ket qua phan irng ddng phan hda hdn hgp n-penlan va n-hexan vdl xiic lac [C5H5NH]C1/A1C13 (1 O^C; 1 gid; li le thi tich n-hexan/IL = 0,4; phan mol cua AICI3 = 0,64; chat khai mao i-CsHnOH)
Nguyen lieu dau Thanh ph^n san pham, (% kl)
khi isopentan 2,2-dinietylbutan 2-metylpentan 3-metyipentan tnetyi-xiclopentan xiclohexan
c„
Do chuyen hoa (% kl) RONn - C , + n-C6
7,9 8,1 6,8 19,6 17,9 31,6 5.3 2,9 19 89,2
n - Q
6,1 3,8 6,2 23,8 19,9 32,3 6,4 1,6 21 88,3
Sy CO mat ciia chat khoi mao lam tang dang ke do chuyen hda ciia phan iing tir 21% den 30%. Tuy nhien, ham lugng cac san pham khi va cac san pham nang (hydrocacbon tir C7 trd len, C7+) cung tang len.
Vi vay, viec sir dung chat khai mao can dugc nghien cuu ky ban dl tim ra ti le thich hgp va Ihu dugc hieu suit va chit lugng san pham tdi uu nhat.
3.5. Phan irng dong phan hda vdi hon hgp ff-pentan va n-hexan
D I md phdng cho phan ung ddng phan hoa condensat vdi xiic tac la chat ldng ion (C2H5)3NHC1/A1C13, chiing toi tien hanh thyc hien
Kha nang phan irng cua n-C; thap han n-Cf, nen khi thuc hien phan irng ddng phan hda hdn hgp hai hydrocacbon nay thi dd chuyen hda giam.
Phu gia CuCI lam tang hieu suat va chat tugng san pham do bien ddi tinh axit ciia chat xuc tac. Khi su dung chat khai mao isoamyl ancol thi hieu suat lang nhung ddng thdi san pham nhe cung tang len do tdc dp phan irng cracking tang.
T A I L I E U THAM K H A O
I Yoshihiro Suki et al. Catalyst composition for the isomerization of n-paraffin and a process for isomenzing n-paraffin, US 7 119 042 B2 (2006)
TCHH,T.51(1),2013
2. G, Boskovic et al. Activation of Mo-based catalyst for paraffin isomerization. Applied catalysis: General
A 317, 115-182(2007)
3. Rui Zhang, Xianghai Meng, Zhichang Liu, Jiaying Meng and Chunming Xu. Isomerization ofn-Pentane Catalyzed by Acidic Chloroaluminate Ionic Liquids Ind. Eng, Chem. Res., 47(21), 8205-8210 (2008).
4. Bill Thj L? Thiiy, Phan VSn Ninh. Nghien cuu phdn ung dong phdn hoa n-parafin nli? sir d{ing chdt long ion di tu pyridin lam chdt xtic tdc, T^p chi l-I6a hpc, 48(4C), 153-158(2010).
5. Y, Ono, T. Tanabc and N Kitajinia The Synergism
Nghien ciru phdn ung dong phdn hda...
of AlClj-CuCl mixture in the low-temperature conversion of pentane, Joumai of Catalysis, 56, 47- 51(1979).
Shi Zhen-min, Wu Xiao-hui, Li Zhi-chang, Meng Xiang-hai. Influence of initiators on isomerization of normal hexane catalyzed by ionic liquids, Joumai of fuel chemistry and technology, 36(3) (2008).
Y, Ono, T. Tanabe and N. Kitajima, The Synergism of AICI3-CUCI2 mixture in the low-temperature conversion of pentane. Joumai of Catalysis, 56, 47- 51 (1979).
Lien h?: Biii Thj L | Thiiy
Trudng Dai hgc Md-Dja chat Ha Ngi Ddng Ng^c - Tir Licm - Ha ngi Email: [email protected]
