Nghien ciru chat xuc tac
cho qua trmh khi hba chat thai huTucGfvasinhl^hdi
• Bill TI^N TRINH"^ • NGUYEN HONG ANH"
• NGUYEN HOAl NAM* • D O A N V A N BINH' • L £ X U A N QUE"
DVIEN KHOA HOC NANG LUONG - 2)TRU0NG DAI HQC TAl NGUYEN VA MOl TRUONG - 3)VieN KY THUAT NHIET 001
1.Gidiithi$u
Chat thSi hCru co la mot trong nhOng van de cap bach ve moi trudng d Viet Nam, khong chi vdi cac thanh pho ldn ma 6 cS khu vi/c nong thon. Hien nay khoang 70% dan so (65 trieu ngUdi) la ndng dan dang lam viec trong ITnh vuc ndng nghiep va smh song tai khu vuc ndng thdn 6 cac vung que ngudi ta udc ti'nh rSng cd kho3ng 13 trieu tan chat th^i trong do chu yeu la chat thai hUu CO t h i i ra hang nam. Cdn d Ha Ndi con sd nay \in den 5 000 tan chat th^i mdi ngay va d thanh phd Ho Chi Mmh la 7.000 tan, trong do 50% la
chat thai hUuco.
Can lUu y rang chi mdt nUa sd chat thSi duoc xii iy bSng each chdn trong khi phan cdn lai chi tap trung vao cac bai rac thanh phd. Tuy nhien cho den nay van de da dUOc giai quyet. Mdt hudng di da dUOc chap nhan dd la rac duoc ddt chay tai cho trong cac Id ddt phu hop.
Cd rat nhieu loai Id dot rac vdi cdng suat khac nhau. Ld nhd nhat la vdi cdng suit 1 kg/h, 16 nung nhd vdi cdng suit 5 - 10 kg/h, Id nung vdi cdng suit 15
kg/h den 50 kg/h, va Id vdi cdng suat hon 50 kg/h.
Tuy nhien, van cdn cd nhiing thieu sdt, chang han nhu cac Id dot khdng dUOc sCcdyng vdi c h i t xuc t i c , d6t chay " t u nhien", do dd khi t h i i , khi smh ra khi dot chiy, la khdng k i l m soat dugc cua cac thanh p h a n . , va vi v i y vdi hang ngan 16 dot chi g i l i quyet m d t phan cua van de dd la g i l m so luong chat thai chdn.
Mdt trong nhCfng diem quan trpng do la chpn Id dot phu hgp cho cac khu 68 rtfOiviTuEuxAi'DUW
Coarse iron Powder . Acetone ~
Ty le H5n hgrp nghien giOa Bi/bOt = 10/1
Cdi d|tch^i5$ nghien
(che dg.thiri gian) Ti^n hdnh nghien
LirutrO Bgt sJt mjn Ldmkh66nhigtiia50°C
trong 30 phUt
i
TAch Acetone
So do 1 .Cac bi/dc trong qua trinh nghien ca khi de tao ra bdt sat n
viic din cu nhd, dac biet la cac xa ndng thon Viet Nam.
Khi hda la mdt qua trinh nhiet noi ma chat thai hQu ca dUdc chuyen doi thanh mot Icai khi hCiu ich sU dung cho nhieu CO sd khi hda. Khi sin xult co the dugc stfdung cho nhieu muc dich. Mox trong nhOng Ung dyng quan trong nhat cua khi la duoc ddt chiy sinh nang luong va sinh nhiet hoac lam nhien li§u khf thd (chua qua tinh che) cho sin xult nhien li&u hoac hoa chat.Tuy nhien khi khi hda rac thii hCfu co khdng chi smh ra khi nhien lieu hOu ich ma cung cd mdt sd san phim phu khong mong mudn.
Trong so d6,tar (nhua hac in) dugc cdng nhin la mgt trong nhQng vin de nan gili trong bit ky h^ thdng khi hda nao.
Hon nQa, cac loai hic in nguy hiem vi khi nang gay ung thu va nd cd chQa mdt lugng dang ke nang luong cd the dugc chuyen giao cho nhien lieu khi nhu H2, CO, CH4,v v Ngoai ra.nong dd cao cua hIc in the gay hu hdng hoac gay khd khan khi bio tri cho ddng co va tua-bin.
2. Chat xuc tdc goc sat.
Phu gia sat da thu hut them su chu y cua cac nha nghien cQu. Liu da nghien cQu cac phu gia khac nhau (Fe, Ivlg, Mn, Ce) cho cracking xuc tic cua hIc in sinh khdi thdng qua Ni6.
Gin day chit xuc tac goc s5t va / palygorskite [2-4]. Liu [2] da phat hien ra ring hieu Ung cua cic chat phu gia (Fe. Mg, Mn, and Ce) tren xuc tac 6%Ni/
PG la khac nhau Trong sd cic phu gia, hieu Ung cua Fe tren xuc tie 6%Ni/PG II manh hon so vdi Mg, Mn, and Ce, V\ic chuyen hda hIc in va sin luong H2 tuong Qng la 98,2% va 56,2% trong khi
ham iuong Fe cho vao da tang len 8%.
Hop kim Fe-Ni va khoang chat Fe-Ni da dugc phit hien trong xuc tac 6%Ni/PG dugc dieu chinh bdi Fe. Fe da lam ting hoat tinh xuc tac cho viec phi vd lien ket C-C va C-H, Fe cung lam tang lang dong carbon va ting su hinh thanh H2 va cho thay hieu Ung ket hap cac thanh phan hoat tinh cua Fe va Ni.
LIU [4] cung da nghien xuc tic craking cua hIc in tQ vec khi hda vd trau difdi su giijp dd palygorskite Fe va Ni. Khi so sanh viec lang dong carbon da nhin ra ring viec lang dgng carbon tren cic chat xuc tac Fex-Ni6/PG la cao hon so vdi Fe6-Niy/PG tren toan dien. Hon nQa, hai con sd nay cijng cho thay Inh hudng cua Ni va Fe tren sang luong H2 cd ngudn gdc tQ viec xuc tac cracking nhua sinh khoL TQdd nhan thay ring ham luong sat cao cd the cai thien viec chuyen doi carbon va ham lugng nikel rao da lam thuan loi cho su gia ting sin lugng H2 Rd rang, nd chi ra ring viec bd sung Ni dong mdt vai trd quan trgng hon trong viec giam lang dong carbon so vdi FeNhutadl biet ro, viec lang dong rarbon se lam gilm hoat tinh cua xuc tic. Vi viy, cic chit xuc tac Fee-Niy/PG cd the co hoat tinh lot hon so vdi cac chat xuc tie Fex-Ni6/PG cho viec cracking xuc tac cua nhua sinh khdi de cd H2 giau hon trong cac sin pham phin utig. Cac chuoi phin Qng trong qua trinh cracking xuc tac nhua smh khdi da dugc thuc hien thong qua chat xuc tIcFe-Ni/PG. Nd chi ra rang dudi tac dung cua Fe-Ni/PG nhua sinh khdi cd the dugc chuyen doi thanhC, H2, CO, CH4 va hydrocarbon nhe, trong dd palygorskite chU yeu ddng vai trd dan dat va tuong tie giQa cic oxit niken/niken va oxit sit/sat la thanh
phan quyet dmh cua phin Qng.
3. Che tao Nano sat 3 1 Thuc nghiem [5-8]
May nghien bi hanh tinh Fritsch P-6 cd 4 tram nghien, d dd vai tram gram bdt cd the duoc nghien cung luc. Miy nghien bi hanh tinh cd ten nhu vay la do chuyen ddng kieu hanh tinh cua cae Ig thuy tmh cua nd Cac Ig nay dUOc bd tri tren mdt dia dd cd the quay va mdt CO clu dan ddng quay quanh chinh cic true eua no va bdi dia quay Cl 2 tic dong l^n binh thuy tinh chQa nguyen lieu cln nghien va cic vien bi de nghien. Cic binh thuy tinh va dia dS quay theo cac hudng khie nhau tao ra chuyen ddng phUc tap va da dang cua cac vien bi nghien tic ddng nen nguyen lieu duoc nghien.
Cac binh thuy tinh v l cic vien bi cd the duoc che tao tU 8 vat lieu khic nhau - agate, silicon nitride, sintered corundum, zirconia, chrome steel, Cr- Ni steel, tungsten carbide, and plastic polyamide. Cic binh thuy tinh va cac vien bi trong nghi#n cQu nay da dQoc che tao tQ tungsten carbide Qui trinh nghien cua cdng tie che tao bdt sat dugc md ta trong so do 1. Vat lieu tho cua May nghien bi hanh tmh Fritsch P-6la bdt sit thd dugc chuan bl bdi phQOng phap lang dong dien hda. Ki'ch thudc hat trung binh la 160 micromet, hlnh dang hat ddng nhit, hinh thii duoc quan sat bdi FE-SEM (hinh 2a), dd tinh khiet >97,4% (bang 2). Ty !e bi/bgt II iO/1 De gilm thieu su 0X1 hda, thao tac nghien da duoc thuc hien trong acetone khan. Acetone khan nay dUOc cho vao cic lo thijy
Bang 1: Ky hi$u va cac tham so diu vao ciia may nghien bi hanh tinhFiltsdi P-6, ch^ dp nghien P6.1 Miu
Khoi luong (g/flot/lo) Then gian xay (h)
_ N5 _ j .
Bang2. Thanh phan hoa hpc cua mau NO vaN6,Ket qua thu dUcrc khi phan tich qua pho tan sac tia X (EDX)
3 ;
1 1 1 L.
Hinht. Nang lucmg phan tan pho tia X cua bot s^t (a) khong nghien va (b) sau 30 gid nghien.
tinh trUdc khi nghien. Cac mau thif da duoe nghien vdi gil tn eli dat tai che dp P6.1 (van tdc 500 vdng/phut, thdi gian mdi chu trinh nghien la 15 phut, 5 phut dOng). Cac budc nhu trong so dd 1 Sau cdng doan nghien nhu vay, hdn hgp san pham ciJa mdi me duoc dua ra khdi binh thuy tinh de tich so bd chit hda tan trong mdi trudng khdng cd oxi. Sau 66 bgt sat dUOc lam khd trong chin khdng tai nhiet dd khoang 40-50 oC trong khoang 30 phut Tiep theo san pham duoc bao quan trong moi trudng kin va cd ham luong oxi cue thap (So do!)
Nghien cQu cac mau bdt dugc liet ke trong bing 1, trong dd mau NO ia nguyen lieu khdi dau. Thanh phan va cau true cua cac mau da dugc thQ nghiem tren thiet bi nhieu xa tia X(XRD), loai SIEMENS D5000: Hinh thii be mat va thanh phan hda hoc da duoe xic dmh bdi Kinh hien vi dien til quet (FE-SEM)va pho tin sat tia X (EDX),ioai FESEM S-4800. Su phan bd kich thudc hat dugc xac dinh bdi DLS tren thiet bi HORIBA LA-950. Dien tich be mat cu
(a) -(b) Hinh2.Hlnh thai hoc cua cac mau: NO (a), N1 (b)
(a) '(b) Hlnh3.Hinh anh cua bot sit N4: hat rieng le (a). Cum hat (b) cua bgt s3t.
the va su phin bd eie 16 hong da duoc xac dinh bang viec sQ dung phuong phap hap thu dang nhiet cua Ni to (N2) tren ASAP 2020V3.01H Vai lUtinh ciJa bdt sat da nghien nhu Ms bao hda. He khing tQ da dUOc xle dmh bing viec sQ dung dudng cong tU hda dQOc xac dinh bdi loai VSM, DMS 880 tai nhiet do phong.
Ki'eh thude tinh the d l duoc tinh toan tQ elc md hlnh nhieu xa tia X theo cdng thUe Seherrer:
Bcos0 (1)
Trong do Dcrysia kich thudc tmh the (nm),e la gdc dinh, \ la bQdc sdng bQc xa tia X(A - 0154056 nm cho Cu-Ka ca tdt)
Kich thQde ciia hat bdt (DBET dugc xle dinh bang cich sQ dung phuong phip Brunauer-Emmen-Teller (BET) va phuang trinh[11]
°'"^^. (2)
n HPCrfvUiAlxATKMG
20 30 40 50 60 2 Th0ta (deg.)
•)
Hlnh 4. M3U nhieu xa qua tia X: (a) Nl, N3, N5, N6 va (b) N0-N6: hai dinh 628 = 44.670 vd82.320tLrong i^g vdi dinh (110) va (211).
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L
10
\
\
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Hlnh 5. Anh hi/dng cua thdi gian nghien ISn kkh thudc tinh th^ cda bot sat.
Trong dd p la tl trong neng (g m-3) va Ss la dl^n tich b^ mit cua bdt sat (m2.g-l), (Bing 1)
3.2.Thinh phan va cau true tmh the Nguyen lieu thd va cac san pham nghien dugc phin tich de xac dinh thanh phan cCia kim loai sit /sat oxit bing phuong phip phin tich phd tin sic tia X (EDX), Ket qua eho thay rang vdi thdi gian nghien khoang 1-30 gid, dg tinh khiet cua t i t ea cae san pham (sit kim loai) la rit cao, len tdi 97%
83ng 2 trinh bay ket qua thu dugc cua viec phan tich, mau NO - ma khdng can nghien, mau N6 - nghien 30 gid. Cic gil tri tfung binh cUa ty le phan tram theo trong luong cho thiy su gia tang cua cac thanh phin tap chit (oxit sit), nhung rat nhd SU khic biet ve dd tmh khi^t eua mau N6 so vdi mau NO ban diu II ehi 0,70% khdi luong, cd nghla II cd gin nhu khdng cd qua trinh oxy hda xiy ra trong qui trinh chuan bj Cic hinh Inh pho nhieu xa tia Xcua mau NOva N6 dugc the hien trong hinh la
Hinh 6. BuiJng cong phan bo kich thudc hat cOa cdc mSu N3, N4, N5 va N6 duoc xic djnh b^ ky thuat DLS (khdng nghien) va lb (30 gid nghien) Ket qui nay cho thay khong cd thay doi giQa phd EDX thim ehi thdng qua viee ting thdi gian nghien len den30 gid Qua trinh nghien, eung nhu viee xil ly va iQu trQ cua sin pham khong tao ra bit ky dinh mdi trong phd nhieu xa tia X, khi so sinh vdi nguyen lieu thd, die biet la ty le phin trim eua oxy 11 gin nhu khdng tang. (Hinh 2}
Ket qui quan trie thu duoe bangFE- SEM cho thay cic giai doan dau cua qua trinh nghien, cae hat bdt ion bi can det de tao thanh tam mdng vdi dd day nhd, nhung dien tich be mat cua chung da rdng hon (hinh 2b). Khi thdi gian nghien it hon 5 gid, elc hat dat kich thude mdt vai chuc micromet Khi thdi gian nghien dUOc ting len den hon Sgid.quan sit tren FE-SEM hinh anh cho thay mgt su hien dien dang ke sd luong elc hat neng le cd kich thude tQ 50 - 85nm (hinh 3a), nhung chung ehu yeu la lien ket de hinh thanh cae cum hated kich thudc cua vai micromet (hinh 3b).Trong khi thdi gian nghien da khdng ngifng ting len den 10 gid va
Hinh7. Anh hi/dng cua thdi gian nghien len: (a) kich thudc hat trung binh (DDLS);(b) £)Udng cong hieu chfnh khdng tuyen tinh; (c) Dien tich be mat ciJa bot sat(Ss).
nhi^u hon nQa, ket qua do sQ phan bo ki'eh thudc cua ky t h j i t DLS cho thay ring kich thudc trung binh eua elc cum gilm ding ke, nhu the hien trong hinh
Khi thdi gian nghien da dugc tang tQ 1 gid den 30 gid, bieu do nhieu xa tia X (XRD), vdi gdc 26 gia tri trong khoang 200-1000 eua tat ea cac mau tQ NO den N6, ed bon dinh nhieu xa dac trUng cilia tmh the sit eua BCC eau true o-Fe Tuy nhien, chieu rong eua eac dinh nui cd xu hQdng rong han,va cQdng dd dinh gilm Qng vdi tang thdi gian nghien, va mdt iQOng nhd elc manh vd xuat hien tren cic dinh X-quang trong so dd nhieu xa eua Nl, N3, N5 va N6 mau dQOe the hien trong hinh 4a.
Cln cQvao phQOng trinh (1) kich thudc tmh the Derys eua bdt sat da dugc xic dmh bdi thdi gian nghien nhu chi ra trong hlnh 5. Trong giai doan dau cCia qua trinh nghien kich thudc tinh the giam xudng, tuy nhien khi thdi gian nghien tang len hon 5 gid kich thudc cung giam nhung rat cham nhu hinh 5.
Dieu do cd the hieu ring eac vien bi tic ddng len cae hat nhd giam rat nhieu so vdi len elc hat Ion, va thdi gian nghien cang lau se dat den cic tham sd tdi han CLia thiet bl.
Bieu dd nhieu xa tia X, hinh 6, khdng eho thiy bit ky pha mdi nao cho thay qua trinh nghien la hieu qui trong viec bio ve bdt kim loai sat khdi oxy hda Day la ket qua hoan toin phu hop vdi cac giQ lieu dQOe cdng bo.
wo*«ruaix*YM«t 171
3 3. Phan bo hat theo kich thudc Phan bdhattheo kfch thudc eiia cac mau Nl - N6 v l bdt sat ban dau la mau NO (nguyen lieu thd) da dugc phan tich bang kythult DSL Ket qua cho thiy sU thay ddi rat manh me cua dUdng cong phan bo cac hat theo ham cua thdi gian nghien, va dinh cua chung ngay cang hep hon nhu mo t l cua hinh 6. Qc ket qua cung cho thay rang kich thQde hat cua mau NO la trong khoang 30-^ 400 pm, nhQng nhQng mau N4^N6 chl trong khoangi -30 pm, cd nghia la dinh cua N4-=-N6 nho hon khoang 10 lan
Dua tren viec phan bo kich thQde hat, kich thQde trung binh cUa cac hat DDLS da dQOe xac dmh. Dien tich be mat Ss eua bdt sat 6a doge xac djnh bdi phuong phap hap thy dang nhiet Nitrogen Mdi lien quan giQa kich thQde trung binh va dien tich be mat tuong Qng vdi thdi gian nghien dugc chi ra trong hinh 7a va 7c Khi thdi gian nghien tang len tQ 1 gid den 30 gid, kich thudc DDLS giam tQ 160.77 pm tdi 7.21 [im, va dien tich be matting tQxIp xi 1 m2/g tdi 7m2/g.
Kmh nghiem da chf ra rang kich thudc trung binh eua elc hat phu thugc vao thdi gian nghien theo phQong trinh;
Z > . ,
= 2.97xe-
(3)Trong do DDLS la kich thQde trung binh (nm), t la thdi gian nghien (hour) He sd tQOng quan cua phQOng trinh (3) la rit cao dat tdi 0,999.
Phuong trinh thuc nghiem dat dQgc md ta rd mile giam chung cua kich thudc hat theo thdi gian nghien trong khoing tir 1 gid tdi 30 gid theo hinh 7a-b.
Ngoai suy thdi gian nghien len tdi 100 gid san pham dat dugc se dat tdi kich thude hat trung binhDDl_S = 3.76 pm TQong Qng theo quan sat tren thiet bi kinh hien vi dien tQ quet FE-SEM cd cac hat nano sat. Nhung ket qua cita ky thuat DLS ehi ra kich thudc hat trung binh theo pm, nghla la kich thudc hat theo cum. Nhung cum nay ed the quan
sat duoe bang thiet bi hinh anh SEM, hinh 3.
4. Ket luan
Bpt sat duoe sin xult bang may nghien CO hgc may nghien bi hanh tmh Fritsch P-6 vdi thdi gian nghien trong khoang tQ 1-30 gid thi bgt sat dat duoc cd nhQng die tinh chung nhQsau:
- Hinh thli, cau true tinh the, kich thudc hat, do xdp v l dd tQ hda bao hda, do khang tQ thay doi theo thdi gian nghien. Khi thdi gian nghien ting len kich thudc hat va do tQ hda bao hda giam nhung do xop lai tang.
- Cau true tinh the cua BCCa-Fe da khdng thay doi trong qua trinh nghien.
Sin pham bdt sat thu dQoe eua do tinh khiet cao>97%. SQ gia tang eua cae thanh phan tap chat la rat nhd, trong tong sd 0,70%, thanh phan bdt sat duy tri tuong tQ nhQ thanh phan cua nguyen lieu thd. Khdng cd pha tinh the mdi xuat hien trong thanh phan bdt sat die biet khdng cd pha oxit s l t - Dien tich be mat san pham bdt sat tang 7 lan trong khi dudng kinh Id hdng trung binh gilm tQ70nm va dat den do dn dmh d xap xi 20nm trong khoang 30 gid nghien. Cae bdt sat cd dmh dang eua vat iieu mesoporous. Dien tich be mat cac Id hong ddng gdp 10% tdng dien tich be mat bgt sat - Trong khoang 30 gid nghien, kich thudc hat cua bgt sat dugc tfnh toin bdi BET dat 1 OOnm; kich thudc hat quan sat bdi FESEM nam trong khoang 50- 85nm; dUdng kinh trung binh cua cac Id hong la 18nm; kfch thudc tmh the dat 7nm; do tQ hda bao hda la 145emu.g-1 Dd khang tQ ia 61-570e Tuy nhien, d c hat nano cd the tap hgp lai den hang chuc mocromet theo quan sit tQ hinh anh eua kinh hien vi dien tQ FESEM Nd cd the tao phd gia trong phin tich.
-Them vao dd, cac ket qui thuc nghiem cho thay rang acetone khdng gay hdng san pham nghien va dim bao vai trd cua nd nhu mdt mdi trucfiig l o ve cho qua trinh nghien sat Nd cd the dugc ap dung cho che tao cac vat lieu de oxy
ho3 khac bang kythult nghien bi nang lucflig eao.
Tai lieu tham khao
1. Nordgreen T, Nemanova V, Engvall K, SJostrom K. Iron-based materials as ' tar depletion catalysts in biomass
gasification: dependency on oxygen , potential. Fuel 2012,-95:71-8.
2. Liu HB, Chen TH, Zhang XL Li JH, Chang DY, Song L Effect of additives on catalytic cracking of biomass gasification tar over a nickel-nased catalyst Chinese Journal of Catalysis 2010;31.409-14.
23. Liu HB, Chen TH, Chang DY, Chen D, He HP, Frost L Catalytic cracking of tar derived from rice hull gasification over palygorskite-supported Fe and Ni Journal of Molecular Catalysis A:
Chemical 2012; 363-364:304-10.
4 Liu HB, ChenTH, Chang DY, Chen D. Kong DJ, Zou XH, et al. Effect of preparation method of palygorskite- supported Fe and Ni catalysts on catalytic cracking of biomass tar.
Chemical Engineering Journal 2012;
188:108-12.
5. Oue L X, Trinh B T et al. 2011 Vietnam J. Chem. Appl.6 32(in Vietnamese).
5.VyUV,QueLX,HoaTT,HuongTT,Tich N V and Huong D T 2009 Preparation of LaNiS-based nano materials by arc- meltmg and mechanic milling Proc 6th Nat Conf on Solid state physics and materialsscience (November, 8th-10th, Da Nang, Vietnam) p. 1186 - 1189 (m Vietnamese).
7. 801 TI^N TRINH, LE XUAN ( NGHIEN Ci^U ANH HJCJNG CUA 1 GIAN NGHlfN OEN TI'NH CHAT ( SAN PHAM BOTSATTAP CHI HOA F
&LfNGDUNG,SO2/2013,TR 33- 8. Bui Tien Trinh, Le Xuan Que fonming ironpovi'der using ^ grinding and determini Its properties, Viet Nam chemistry, Vol-50 {6B), pf 2012 •
7 2 I lAFtHWAruEuxAYDONt
