46061883-nghiencuuxuctac

7/30/2019 46061883-nghiencuuxuctac

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n tt nghip: Nghin cu xc tc Pd-Me /C*cho qu trnh hydrodeclo ha

PHN 1

TNG QUAN L THUYT

1.1. t vn

1.1.1. Hp cht clo hu c: c tnh - ng dng - nh hng ti h sinh thi

Hp cht clo hu c l hp cht m trong phn t c cha mt hoc nhiu

nguyn t clo gn vi gc hu c. C th phn loi cc hp cht clo hu c thnh:

Hp cht clo hu c no, khng no v hp cht clo hu c thm.

Hp cht clo hu c no c cha cc nguyn t clo lin kt vi mt gchydrocacbon no mch h hoc mch vng. V d etyl clorua CH3-CH2-Cl.

Hp cht clo hu c khng no c cha cc nguyn t clo lin kt vi mt gc

hydrocacbon khng no mch v hoc mch vng. V d TTCE Cl2-C=C-Cl2.

Hp cht clo hu c thm c cha cc nguyn t clo lin kt vi mt hay

nhiu vng thm. V d Benzyl clorua .

V ngun gc, mt s t cc hp cht clo hu c hnh thnh t cc hin tng

t nhin nh trong khi ni la, chy rng, cn a s l kt qu ca cc qu trnh

tng hp nhn to.

Cht clo hu c c s dng rng ri trong cng nghip nh c tnh ty ra

tt. Chng thng c dng trong cc quy trnh git l, lm sch b mt kim loi,

ty du m nhn. Ngoi ra, chng cn c ng dng lm dung mi, ph gia,

nguyn liu tng hp nha. V d: Diclometan lm ha cht ty sn, sn xut cht

to bt; vinyl clorua l nguyn liu sn xut nha PVC; tricloetylen l ph gia sn

xut keo, 1,4-diclobenzen dng sn xut thuc tr su, thuc nhum, ha cht

Nguyn Th Thanh Bnh Cng ngh Hu c Ha du 1 K50 Trang 2


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kh mi trong nh v sinh, thuc dit mi; pentaclophenol dng sn xut thuc

st trng

Mi nm trn th gii sn xut v tiu th khong 24 triu tn cht clo hu

c. Sau khi thi ra mi trng, chng tch ly li gy nguy hi cho mi trng v

sc khe con ngi. Trong h nc ngm v nc thi cng nghip thng tm

thy mt s hp cht nh DCE, TCE, TTCEvi nng khng nh.

Cc hp cht cha clo a s gy hi cho sc khe con ngi, chng c vi

da v mt, khi ht phi cc hp cht cha clo d bay hi c th gy bun nn, ngt

xu, hn m, thm ch t vong. c bit, cc hp cht clo hu c khi i vo c th

ngi c kh nng tch ly v tn ti rt lu, chng gy ra nhiu loi bnh c tnh

di truyn. V d: DDT (di-(para-clophenyl)-tricloetan) l hp cht cha clo c

s dng rng ri sau chin tranh th gii th hai phng chng st rt, st pht

ban, ng dng trong cng ngh sn xut vi si. Tuy nhin, DDT tch ly trong c

th ngi gy cc bnh v thn kinh v ung th. Dixin l cht c chin tranh,

ngi nhim phi dixin sinh ra con ci d tt, di chng ko di qua nhiu th h.

i vi mi trng, cc hp cht clo hu c gp phn ph hy tng zn, gy

ma axit v c hi vi cc sinh vt sng. V d dixin c th hy dit c h sinh

thi, CFCs (clo flo cacbon), tetraclorua cacbon, metyl cloroform gy suy gim tng

zn trong tng bnh lu. Vic ny lm gia tng cng bc x ca cc tia cc

tm, lm cht cc sinh vt ph du trong nc bin, gy ung th i vi con ngi

v ng vt. Cc hp cht clo hu c c mch vng thng c cu trc n nh,

tn ti rt bn vng v lun chuyn trong mi trng thng qua chui thc n.Thi gian phn hy cc hp cht ny ko di ti hng chc nm, rt kh x l

chng mt cch trit v i khi vic x l li sinh ra nhiu sn phm ph c hi

hn.



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V nhng l do , chng ta cn phi c bin php gim lng pht thi cc

hp cht clo hu c v nghin cu x l trit chng trc khi thi ra mi

trng.

Hnh 1 v 2 m t lng cht clo hu c pht thi ra mi trng khng kh v

nc ti cc nc Ty u trong mt s nm qua.

Hnh 1: Lng cht clo hu c pht thi ra khng kh ti Ty u [2]

Hnh 2: Lng cht clo hu c pht thi ra mi trng nc ti Ty u [2]



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T hai hnh trn ta c th thy, cc nc Chu u ang t ra mc tiu gim

thiu lng hp cht clo hu c ra mi trng. C th mc tiu l ti nm 2010

gim 50% lng cht thi cha clo vo khng kh v gim 75% lng cht thi

cha clo vo nc, so vi nm 2001.

1.1.2. Hp cht tetracloetylen (TTCE) [1,2]

a. c tnh ca TTCE

Tetracloetylen (TTCE) c cng thc ha hc l C2Cl4, tn quc t l:

tetrachloroethene hay perchloroethylene, perchloroethene, perc, hoc PCE, c cng

thc cu to nh sau:

TTCE l mt cht lng khng mu, khng bt chy v c mi c trng.

TTCE khng c sn trong t nhin m c tng hp vi khi lng ln trong

cng nghip ha cht.

TTCE d bay hi, n d b ph hy khi tip xc vi cc kim loi mnh (Ba,

Li), xt n da, kalicacbonat, cc xit mnh. TTCE tan c trong ru, te,

benzen, chloroform, du, hexan v ha tan c nhiu hp cht hu c.

Bng 1 a ra nhng tnh cht vt l c trng ca TTCE.



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Bng 1: Mt s tnh cht vt l quan trng ca TTCE.

Khi lng phn t M, g.mol-1 165,8

Nhit si (101.3 kPa), oC 120

Nhit nng chy, oC -22,7

T trng , g/cm3 1.622

p sut hi (20oC), kPa 19

nht (20oC), mPa.s 1.62

tan trong nc (20o

C), g.kg-1

0,15b. Sn xut TTCE

TTCE c sn xut bng con ng clo ha hoc xyclo ha nguyn liu

gc nh propylen, dicloetan, clopropan hoc clopropen.

Michael Faraday l ngi u tin tng hp c TTCE bng phng php

phn hy nhit t tetracloetan, phn ng nh sau:

C2Cl6 C2Cl4 + Cl2

Hu ht TTCE hin nay c sn xut bng phng php clo ha cc hp

cht hydrocacbon nh nhit cao. V d: phn ng ca 1,2 dicloetan vi clo

400 oC thu c TTCE, phng trnh nh sau:

ClCH2CH2Cl + 3 Cl2 Cl2C=CCl2 + 4 HCl

Xc tc cho qu trnh l KCl v AlCl3 hoc C*, sn phm chnhTTCE c

thu li bng phng php chng ct.

c. ng dng ca TTCE

http://en.wikipedia.org/wiki/1,2-Dichloroethanehttp://en.wikipedia.org/wiki/1,2-Dichloroethanehttp://en.wikipedia.org/wiki/1,2-Dichloroethanehttp://en.wikipedia.org/wiki/1,2-Dichloroethanehttp://en.wikipedia.org/wiki/1,2-Dichloroethanehttp://en.wikipedia.org/wiki/Hydrogen_chloridehttp://en.wikipedia.org/wiki/1,2-Dichloroethanehttp://en.wikipedia.org/wiki/Hydrogen_chloride


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TTCE hin nay l mt ha cht thng mi cng nh l mt hp cht trung

gian quan trng trong cng nghip ha hc. Sn lng sn xut TTCE nm 1995

trn th gii c tnh t 712000 tn, TTCE sn xut ra c s dng trong cc

lnh vc ch yu sau:

55% lm hp cht trung gian trong cng ngh tng hp hu c: l

nguyn liu cho vic sn xut cc dung mi v cht ti lnh nh R113, R114 v

R115. TTCE cn dng sn xut cc cht thay th CFC nh HFCs v HCFCs

25 % TTCE c dng cho cng nghip lm sch v ty du m b mt

kim loi nh c tnh ha tan chn lc nhiu hp cht hu c v v c.

15 % TTCEc s dng trong cng nghip git kh lm sch vi si.

TTCE c s dng nh mt dung mi c kh nng loi b du dnh vi si sau

khi an, dt cng nh cc qu trnh s dng my mc khc. l nh kh nng

lm sch du, m, hydrocacbon m khng lm nh hng ti bn cht ca vi si

ca TTCE.

5%cn lic s dng vo cc mc ch khc nh lm cht tuyn kh,mc in, thuc nhum, cht bi trn

d. nh hng ca TTCE ti mi trng v con ngi

Hng ngy, hn 90% TTCE s dng c thi trc tip ra mi trng

trong 99,86 % thi trc tip vo khng kh, 0,13 % vo nc v 0,1% vo t,

lng TTCE ny v ang gy ra nhng hu qu nghim trng ti mi trng v

sc khe con ngi.

Khi TTCE c thi vo khng kh, n thng b phn hy sau mt vi tun,

to ra nhng hp cht gy nh hng xu ti tng zn. Khi con ngi tip xc

vi TTCE c trong nc thi, kh thi cng nghip trong mt thi gian lu, vi



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mt nng nht nh s c triu chng bun nn, au u, chng mt, nu nng

hn c th dn n hn m v t vong. TTCE thng gy ra cc bnh v thn kinh,

gan, cc bnh ng h hp cp tnh v mn tnh, ngoi ra TTCE l nguyn nhn

dn n nhiu loi bnh ung th.

Theo thng k ca c quan dch v sc khe v con ngi (DHHS), TTCE

nm trong s 31 cht c xut hin nhiu nht, nguy him nht i vi sc khe

con ngi.

Theo tiu chun nc thi cng nghip TCVN 5945:1995, hm lng TTCE

cho php trong nc thi cng nghip loi A, B, C l 0,02; 0,1; 0,1 mg/L.

Chnh nhng tc ng nguy him ca TTCE i vi con ngi v mi trng

sng nh vy, cc nh khoa hc trn th gii ang khn trng nghin cu tm ra

phng php gim nhng nh hng bt li ny.

1.2. Cc phng php x l hp cht clo hu c

Hin nay cc phng php chnh ang c s dng x l cc hp cht clo

hu c l: phng php xy ha, phng php kh, phng php sinh hc,

phng php kt hp xy ha kh.

1.2.1. Phng php xy ha

Bn cht ca phng php xy ha l t cc hp cht cha clo nhit

cao, c hoc khng c mt ca cht xc tc. Cc sn phm to ra gm c CO2 , H2 ,

Cl2 v mt s sn phm ph khc. Hin nay, phng php ny l con ng nhanhnht, d nht x l TTCE trong nc v kh thi.



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a. Phng php xy ha khng s dng xc tc [3]

Phng php xy ha khng s dng xc tc l qu trnh ph v lin kt clo

trong phn t bng cch thiu t hp cht clo hu c trong dng xy khng kh

nhit cao (hn 900 oC). Phng php ny t ra km hiu qu v chi ph rt cao.

Mt khc n nguy him v sau khi t to ra cc sn phm ph nh ixin v

ibenzfuran, l nhng hp cht cn c hi hn gp nhiu ln.

b. Phng php xy ha c s dng xc tc [7, 11]

u im ca phng php ny l chuyn ha ca qu trnh cao, hn 90%.

Cc hp cht cha clo c bin i thnh cc hp cht an ton hn nh CO2,H2O v Cl2 nhit 550oC, thp hn so vi phng php khng s dng xc tc.

Xc tc thng s dng trong qu trnh ny l Pd hoc Pt trn cht mang -

Al2O3, tuy nhin xc tc Pt thng b ng c bi chnh hp cht cha clo. Hng

nghin cu hin nay ca cc nh khoa hc trn th gii l nng cao n nh ca

hot tnh xc tc, c th thay i t l kim loi qu Pd, Pt, thay i nhit phn

ng, ch hot ha xc tc, lu lng dng H2.

nh gi chung v phng php xy ha, u im ca n l phn hy hon

ton mt s hp cht clo hu c, cng ngh khng phc tp. Tuy nhin phng

php ny c mt s nhc im ln nh: Km an ton, khng tn dng c sn

phm, gy nhim mi trng. Trong phng php xy ha, vic thu gom, vn

chuyn hp cht clo hu c n ni x l tng i phc tp, nguy him v tn

km. Vic sinh ra cc sn phm ph c hi hin cha c cch khc phc.Vic t

chy cng lm tng ng k lng pht thi CO2 ra mi trng, gy mt cn bng

sinh thi, c th dn n thay i kh hu. L do l a s cc hp clo hu c l do

con ngi tng hp nn ch khng phi sn c trong t nhin. Hn th na,

phng php ny c nh gi l khng xanh, trong khi xu hng sn xut



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hin nay ang l: hn ch pht thi ra mi trng, tn dng ngun thi trong cng

nghip ti ch.

1.2.2. Phng php sinh hc [2]

y l phng php s dng cc loi vi khun c kh nng phn hu c

cc hp cht clo hu c thnh cc sn phm t c hi. S dng k thut ny m

bo cc sn phm ca qu trnh khng gy nhim mi trng v khng c hi i

vi sc khe con ngi. Tuy nhin phng php ch c th x l cc hp cht clo

hu c vi s lng khng nhiu m li cn thi gian x l kh di. Cc sn phm

ca qu trnh to ra khng c ti s dng vo sn xut. Do vy, k thut ny

cha gii quyt c tt c cc vn nhim, c th kt hp vi cc phng

php khc t hiu qu cao hn.

1.2.3. Phng php kh

Thng thng dng H2 kh clo ca cc hp cht clo hu c s dng cc kim

loi qu v kim loi ph tr mang trn mt s loi cht mang, c tc dng ct t

lin kt C-Cl sau thay nguyn t Cl bng nguyn t H, phng php ny gi l

hydrodeclo ha (HDC).

u im ca phng php ny l tc phn ng nhanh, hiu sut cao,

khng to ra cc sn phm c hi cho mi trng, c li v mt kinh t.

im gii hn cho qu trnh kh trong cng nghip l chn lc v n

nh hot tnh ca xc tc. Cc hng nghin cu hin nay ang tp trung vo vic

nng cao thi gian sng ca xc tc, chn lc ra cc sn phm c gi tr cao trongcng nghip.

Bng 2 m t cc nghin cu v xc tc qu trnh HDC trn th gii



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Bng 2: Cc xc tc thng dng cho qu trnh HDC [7]

XC TC I TNG CN X L

NiMo/Al2O3 Chlorinated benzenesNi/Mo - Al2O3 Dichloromethane, 1,1,1-TCA, TCE, PCE

Pd/C 1,2,4,5-Tetrachlorobenzene

Ni/SiO2 v zeolite Y Chlorophenols, dichlorophenols,

trichlorophenols, pentachlorophenol

Pd/Al2O3, Rh/Al2O3 Chlorobenzene

Pt/C, Pd/ - Al2O3 4-Chloro-2-nitrophenol

Rh/SiO2 Dichloroethane (DCA), TCE

Pt/Al2O3 Dichloroethylene (DCE)

Pd/C* Chlorofluorocarbons

Pt/cc cht mang Carbon tetrachloride (CCl4)

Pt/ - Al2O3 Carbon tetrachloride

Pt/MgO Carbon tetrachloride

PdO/ - Al2O3 1,1,2-TrichlorotrifluoroethaneNi/zeolite Y Carbon tetrachloride

PdCuSn/C* PCE

PtCuAgAu/C* 1,2-Dichloropropane

Ni/ ZSM-5 v Al2O3 TCE and TCA

Pd/C TCE, TCA, and chlorobenzene

Pd/ Al2O3, AlF3 1,1-Dichlorotetrafluoroethane,

dichlorodifluoromethaneCc kim loi nhm VIII Dichlorodifluoromethane

Pd, Rh, Pt/ Al2O3 PCE

Pd/SiO2 1,1,1-Trichloroethane (TCA)

NiMo/ Al2O3 PCE, TCE, 1,1-dichloroethylene, cis-



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dichloroethylene and trans-dichloroethylene

Pd/ - Al2O3 CF2-Cl2 (CFC-12)

Ni-Raney, Ni/ SiO2, Pd/Al2O3,

Pt/ Al2O3,Pt/Rh/Al2O3,

Ru/ Al2O3 v sulfided NiMo/Al2O3

Dichloromethane, chloroform, carbon

tetrachloride, 1,1,1-TCA, TCE and PCE

Pt/ Al2O3 TCA

Pt, Pd/ Vycor, Al2O3, C, AlF3 Chloromethanes, chlorobenzene

1.2.4. Phng php xy ha kh kt hp [7]

y l phng php mi s dng xc tc l kim loi qu trn cht mang (v

d Pt/Rh/ -Al2O3 ), cng vi dng kh l O2 v H2 mt t l nht nh, a vo

thit b phn ng nhit > 400 oC. Phng php ny cho php ph hy cu trc

cha clo ca nhiu phn t. S kt hp c qu trnh xy ha v qu trnh kh mang

li kt qu c bit cao: hiu sut > 90% v xc tc duy tr c hot tnh trong 2

nm. Qu trnh ti sinh xc tc c th c thc hin d dng v thun tin.

C ch phn ng vi tetracloetylen c xut nh sau:

Tng qut:



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Tuy nhin nhc im ca phng php ny l sn phm khng c kh nng

ti s dng, nhit cung cp cho phn ng cn kh ln (>400 oC), nguy c chy n

vn c th xy ra. V vy phng php ny hin mi c th nghim trn m

hnh nh.

1.2.5. Phng php khc

Mt s phng php khc thng dng nh:

Hp ph TCE, PCE, DCE bng C* (vi nc hoc kh nhim bn). Phng

php ny c th tch loi nhng hp cht Clo hu c nhng khng phn hy

chng, cho nn chng ta cn x l su hn.

Kh bng kim loi: dng Fe kh clo ca cc dung dch hu c.

Dng dung mi metanol phn hy mt s hp cht nh PCE.

Cc phng php ny b gii hn bi hiu qu khng cao, quy m nh, tuy

nhin c th l gii php tm thi trong trng hp hn ch v cng ngh.

Trong s cc phng php nu trn, phng php HDC t ra u vit hn hn

v ha hn mt tng lai pht trin bn vng trong nn cng nghip, n ny

nghin cu xc tc Pd-Me/C* cho qu trnh HDC TTCE.

1.3. Phn ng HDC

1.3.1. nh ngha

Phn ng HDC l phn ng ct b lin kt C-Cl ca hp cht clo hu c trong

dng kh H2 v thay th nguyn t Cl bng nguyn t H.

R Cl + H2 R H + HCl

V d:



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CCl2=CCl2 + H2 CHCl=CCl2 + HCl

CHCl=CCl2 + H2 CHCl=CHCl + HCl

CHCl=CHCl + H2 CHCl=CH2 + HCl

CHCl=CH2 + H2 CH2=CH2 + HCl

CH2=CH2 + H2 CH3-CH3

Ngi ta s dng xc tc thc y phn ng xy ra iu kin mm, nhit

v p sut thp.

1.3.2. Xc tc

Xc tc cho phn ng HDC thng c dng kim loi mang trn cht mang.

Cc kt qu nghin cu cho thy Pt, Pd, Ni v Rh c hiu qu tt, n nh cao

hn cc kim loi khc trong phn ng HDC pha kh. Ngi ta c th s dng xc

tc n kim loi, a kim loi, hoc oxit ca cc kim loi chuyn tip nh: xit

ng, xit cban, xit mangan, xit st, xit crm, xit niken.

V cht mang, - Al2O3 v SiO2 l nhng cht mang c kh nng s dngcho xc tc HDC, tuy nhin chng d b tn cng bi sn phm HCl nn b mt

hot tnh nhanh chng. Trong khi C* c gi thnh r, tr v mt ha hc, din

tch b mt ln, tr thnh mt cht mang tim nng cho phn ng HDC pha kh.

a. Kim loi Pd [1]

Pd (palladium) l kim loi qu thuc nhm VIII B, chu k 5, s hiu nguyn

t 46. Pd kim loi c mu trng bc, c pht hin ra t nm 1803 bi William

Hyda Wollsaton. Mui nitrat, clorua ca Pd tan chm trong axit.

Pd c nhiu ng dng trong nhiu ngnh khc nhau:



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Trong ngnh in t: Pd c dng lm in dung gm a lp, u cm bin

in t, hoc lm lp bo v cho cm bin in t v cc mi hn c bit.

Trong cng ngh: Pd dng trong thit b lm sch kh, thit b ch to hydro

tinh khit, l nh Pd c kh nng hp ph hydro tt.

Trong vic lm xc tc: Pd tn mn trn C l xc tc cho qu trnh hydro ha

v dehydro ha, ng dng cho phn ng cracking cc sn phm du m. u im

ca vic s dng Pd lm xc tc l chuyn ha cao, tc dng nhanh. Tuy nhin,

n c nhc im l gi thnh cao, nhanh mt hot tnh.

Ngoi ra, Pd cn c ng dng khc trong cc ngnh nhip nh, nghthut

b. Cht mang C* [1]

C* l mt trong nhng vt liu hp ph tt, din tch b mt ln, t 500 n

1500 m2/g. Ngoi thnh phn chnh l cacbon, than hot tnh cn cha 5-10% khi

lng cc nguyn t khc dng xit kim loi, hydrxit. Trong thnh phn cc

xit kim loi thng cha cc nguyn t: Al, Si, Fe, Mg, Ca, Na, K, S, P.

Mt s c trng ca C* l din tch b mt ring, cu trc l xp, cc c

trng ny lin quan mt thit n tnh cht hp ph ca C*.

Din tch b mt ring l din tch b mt tnh cho mt n v khi lng, n

bao gm tng din tch b mt trong mao qun v bn ngoi cc ht.

Hnh dng mao qun trn b mt C* c th chia ra lm bn loi c bn: hnh

tr, hnh khe, hnh chai, hnh nm. Phn b kch thc ca cc mao qun hoc l

xp c xc nh theo s bin i ca th tch hoc din tch b mt mao qun

vi kch thc mao qun.



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Theo tiu chun ca IUPAC, c th chia kch thc mao qun thnh ba loi:

Mao qun ln c ng knh mao qun trung bnh ln hn 50 nm, mao qun trung

bnh c ng knh t 2 n 50 nm, mao qun b c ng knh nh hn 2 nm.

Trong qu trnh hp ph, ngi ta thng nh gi kh nng hp ph ca C*

thng qua din tch b mt ring v phn b l xp. Din tch b mt ring cng

ln th kh nng hp ph cng cao. Kch thc mao qun ln th dung lng hp

ph thp nhng tc hp ph cao. Cc mao qun ln thng l ni cha cc ht

xc tc kim loi sau qu trnh ngm tm. Vi h mao qun trung bnh, ngoi hin

tng hp ph c th xy ra hin tng ngng t mao qun, khi kch thc mao

qun b thu hp li. i vi h mao qun nh, dung lng hp ph thng cao

nhng tc hp ph chm.

u im ca C* khi s dng lm cht mang cho xc tc l tnh tr, r, din

tch b mt ln. B mt ln ca C* c c l nh cu trc x rng tha hng t

ngun gc hu c v iu kin hnh thnh. Ngoi ra, vic x l C* sau khi dng rt

n gin.

C* c tnh cht kh clo, ngi ta a ra mt thng s dy bn hp ph

kh Clo, o lng hiu qu loi b clo ca C*. chnh l dy cn thit ca

lp C* c th gim mc clo trong dng t 5 ppm xung 3.5 ppm. di ny cng

b chng t hot tnh ca C* cng mnh.

c. Kim loi th hai [1]

St l kim loi chuyn tip thuc nhm VIII, chu k 4, s hiu nguyn t 26.Fe ng dng nhiu nht trong xy dng, ngoi ra, Fe c chn lm xc tc cho

mt s qu trnh nh tnh cht xy ha kh.

Niken l kim loi chuyn tip thuc nhm VIII B, chu k 4, s hiu nguyn t

28. Ni cng c kh nng kh clo nhng hot tnh km hn Pd. Tuy vy, u im



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rt ln ca Ni l r v d kim hn nhiu so vi Pd nn c th ng dng lm xc

tc trn quy m ln.

d. C ch phn ng HDC [6, 7]

Phn ng HDC c gi thit xy ra theo hai c ch: ni tip v song song.

Cc phn ng c th xy ra trong qu trnh HDC bao gm:

Trong * l biu th mt phn hot ng trn b mt xc tc, RClx l hp

cht hu c cha clo.

Phn ng (4) v (6) xy ra trn b mt xc tc, gia phn t RClx v nguyn

t H hp ph trn b mt xc tc. Phn ng (5),(7) l phn ng nh hp ph.

Phn ng tng qut c th vit nh sau:

C th d dng nhn thy: sn phm ca phn ng hydrodeclo ha khng ch

l mt cht khng cha clo m l mt hn hp nhiu cht c th cn cha clo, nn

c ch ni tip khng cn chnh xc. C ch song song m t phn ng HDC tt

hn [7].



18/52


C ch phn ng HDC TTCE vi xc tc n kim loi nh sau:

Hnh 3: c ch phn ng HDC TTCE vi xc tc n kim loi Pd [6].

M t c ch phn ng: u tin, cc tm hot tnh Pd hp ph H2 v chuyn

hydro phn t v dng hydro nguyn t. TTCE cng b hp ph ln cc tm hot

tnh, lin kt C-Cl trong phn t TTCE b nguyn t H v Pd tn cng, hnh thnhlin kt mi C-H v H-Cl. Sn phm phn ng tch ra khi tm hot tnh xc tc

v i ra ngoi.

C th thy vai tr ca kim loi Pd va l ct lin kt C Cl, va l to ra cc

hydro nguyn t (H*) t H2. Hydro nguyn t mi sinh ra s thay th cc nguyn

t Cl b ct i, to lin kt vi Cl cn li to thnh HCl, ng thi cc nguyn t

H cng c dng ti sinh Pd mt hot tnh. Do Pd phi lm c hai nhim vnn kh nng xc tin qu trnh hydro ha TTCE khng cao v kh nng b ng

c bi HCl sinh ra l rt ln. Chnh v vy xc tc cha n kim loi Pd thng

nhanh b mt hot tnh.



19/52


Khi thm kim loi th hai vo hp phn xc tc, Fe v Ni s tham gia vo c

ch phn ng, sau che chn cho Pd khi b ng c bi Cl. Pd vn gi vai tr

hp ph H nguyn t v ct t lin kt C-Cl trong phn t TTCE nh bnh

thng, to ra sn phm C2H6. Kim loi th hai cng tham gia ct lin kt C-Cl

nhng li to ra cc hp cht trung gian. Sau , cc hp cht trung gian ny nh

hp ph kim loi, hnh thnh lng ln sn phm C2H4. Ngoi ra, Fe v Ni c

ng knh nguyn t b hn Pd, che chn cho Pd khi b mt hot tnh bi tc

ng ca sn phm HCl. S khc nhau gia c ch n kim loi v a kim loi l

ch sn phm cui c cha mt lng ln olefin v ch cha mt lng nh

parafin.

1.4. Cc phng php iu ch xc tc [22]

Hin nay trn th gii ang s dng cc phng php iu ch xc tc HDC

nh sol-gel, trao i ion, ngm tm. Mi phng php u c nhng u nhc

im ring:

Phng php sol-gel ng dng vi kim loi mang trn cht mang SiO2,

phng php ny cho ng knh ht kim loi phn tn trn cht mang nh,

phn tn tt. ng knh ca cc ht kim loi sau khi to gel l khong vi nm.

Trong iu kin tt nht, phng php sol-gel to ra tinh th kim loi vi ng

knh 2 -3 nm c nh v trong mao qun ca SiO2. Khi ht kim loi c bo

v v khng b thiu kt trong sut qu trnh hot ng nhit cao. Nhc im

ca phng php ny l quy trnh phc tp, thi gian iu ch xc tc di, cn s

dng nhiu loi ha cht to phc v cu ni trung gian cho qu trnh tng hp.

Phng php trao i ion s dng nha trao i ion. Ngi ta nh t t dung

dch mui kim loi vo cc ng cc ht nha trao i ion v khuy u. Sau

lc, sy cc ht nha, ly cc ht nha kh i kh nhit cacbon. Phng php ny



20/52


cho phn tn kim loi trn xc tc rt cao nhng kh kim sot s mt mt kim

loi trong qu trnh tng hp.

Cui cng, phng php c s dng rng ri nht l phng php ngm

tm.

V d khi iu ch xc tc cho phn ng HDC TTCE, dung dch mui kim

loi (Pd(NO3)2, Fe(NO3)2, Ni(NO3)2) c tm ln b mt C*, sau ta cho bay hi

nc d s thu c kim loi mang trn cht mang. u im ca phng php ny

l tin hnh nhanh, n gin. Tuy nhin, mun thu c phn tn kim loi cao

ta cn khuy u trong v sau khi tm. Xc tc kim loi c chun b bng

phng php ngm tm thng c tm kim loi ln, ng knh ht khong 5-30

nm, phn b hu ht trn b mt cht mang.

1.5. Hng nghin cu ca ti

Trong n ny, em s dng phng php ngm tm tng hp xc tc

lng kim loi Pd-Fe/C* v Pd-Ni/C* v thay i th t tm nhm tm ra xc tc

tt nht cho phn ng HDC TTCE. Nhng nghin cu bc u cho thy, so vi

xc tc n kim loi qu, xc tc lng kim loi th hin nhiu u im r rt v

hot tnh v thi gian lm vic. Ngoi vic tit kim c kim loi qu, s c mt

ca kim loi th hai gip ci thin hot tnh v chn lc xc tc, lm mm ha

iu kin tin hnh phn ng. iu ny m ra trin vng p dng thc t cho phn

ng HDC trong qu trnh x l hp cht clo hu c.



21/52


22/52


Tn ha cht Cng thc phn t Hng sn xut tinh khit (%)

Paladi nitrat Pd(NO3)2.2H2O Merck 99,9

Niken nitrat Cu(NO3)2.3H2O Merck 99,9St (III) Nitrat Fe(NO3)3.9H2O

Nitric acid HNO3 Merck 67

Than hot tnh C*

Dng c cn dng gm c: My khuy t, sng, t sy, l nung, cn, micro-

pipet, cc c m 100ml

2.1.2. Quy trnh tng hp xc tc

Quy trnh tng hp xc tc c m t trn hnh 4.

Hnh 4: Quy trnh tng hp xc tc


Pha dung dchPd(NO

3)

2, Fe(NO

3)

3,

Ni(NO3)

2

Ngm tmxc tc Khuy 3h

Sy 80oC 4h,120oC 3h,

180 oC 1hNung 300oC 3h

Hot ho xc tc300 oC 3h

Cht mang(nghin, sng)


23/52


Cht mang C* c nghin, sng vi mt sng 0,3 mm. Sau dung dch

Pd(NO3)2 , Fe(NO3)3 , Ni(NO3)2 c pha theo nng tnh ton. S dng cc cc

c m 100 ml, mi cc cha 1g C*, thm 3 ml nc deion lm t b mt, khuy

u trong 1h. Dng micro-pipet ly v tm t t cc dung dch Pd(NO3)2 , Fe(NO3)3

, v Ni(NO3)2 vo, th t tm v th tch mi ln tm theo tnh ton. Sau khi tm,

cc cc c khuy u trong 3h, cho bay hi nc d bng cch sy 80 oC

trong 4h, sy 120 oC trong 3 h v 180 oC trong 1h. Nung xc tc nhit 300 oC

trong 3h, tc gia nhit 3 oC / pht. Cui cng, xc tc c hot ha 300 oC

trong 3h, c dng H2/ Ar 10% (80 ml/pht) chy qua.

Xc tc tng hp c dng ht mu en, mn, t l thnh phn ca cc mu xc

tc tng hp c m t trong bng 4

.

Bng 4: Cc mu xc tc tng hp

K hiu mu Hp phn (%) K hiu mu Hp phn (%)

BM 1 100Pd/C* BM 6 75Pd 25Ni/C*

BM 2 75Pd 25Fe/C* BM 7 50Pd 50Ni/C*

BM 3 50Pd 50Fe/C* BM 8 25Pd 75Ni/C*

BM 4 25Pd 75Fe/C* BM 9 100Ni/C*

BM 5 100Fe/C*

2.2. nh gi c trng ha l ca xc tc

2.2.1. Phng php hp ph v nh hp ph vt l N2

Hp ph v nh hp ph vt l N2 hot ng theo nguyn tc:



24/52


Vt liu c hp ph kh N2 ti nhit N2 lng l 77oK. T phng trnh

BET:

( ) 0.

1

.

1

. P

P

CV

C

CVPPV

P

mmaa

+=

Trong :

Va: s mol kh b hp ph p sut Pa,(mol/g).

C: hng s BET.

Vm: th tch cn thit hnh thnh n lp hp ph trn b mt, mol/g.

P: p sut kh (mmHg).

P0: p sut hi bo ho ca cht b hp ph ti nhit cho (mmHg).

C th xy dng c th biu din mi quan h ( )PPVP

0

.v

0P

P

,

l mt ng thng trong khong P/P0 = 0,05 0,3. Da vo h s gc v im

ct trc tung ca ng thng biu th mi quan h gia P/Va(Pa-P) v P/Po, xc

nh c Vm v t tnh c din tch b mt ring S(m2/g) theo cng thc:

S=Vm. an.Na.10-20

Trong :

an: tit din ngang ca phn t Ni, oA.

Na: =6,023.1023 mol-1, s Avogadro

Trn c s xc nh lng N2 m vt liu c th hp ph vo cng nh nh rakhi thay i p sut m ngi ta xc nh c cu trc xp v din tch b mt

ring ca vt liu.



25/52


Trong nghin cu ny, cc mu xc tc c xc nh din tch b mt ring

v cu trc xp iu kin: nhit 77oK trn thit b ca hng Micromeritic

ASAP 2010.

2.2.2. Phng php ICP AES v AAS

ICP-AES (Inductively-Coupled Plasma Atomic Emission Spectrometry) v

AAS (Atomic Absorption Spectrophotometric) l cc phng php phn tch c

ng dng xc nh hm lng kim loi thc t trong cc mu xc tc. Nguyn l

ca cc phng php ny l axit ha, a mu v dng lng, ph v lin kt ca

cc nguyn t kim loi vi nhau v vi cht mang. Ngi ta lm bay hi mu

nhit nguyn t ha, sau o nng nguyn t kim loi t do thng qua mc

hp th hay pht x nh sng ca nguyn t kim loi ti mt tn s quang ph

c trng. T kt qu phn tch ny, ta nh gi c hiu qu ca qu trnh iu

ch xc tc, so snh gia hm lng kim loi l thuyt v thc t, c c s liu

thc t thc hin cc phng php phn tch khc nh hp ph xung CO.

Trong n ny, cc mu xc tc c phn tch hm lng kim loi a ln

cht mang bng ICP AES v AAS ti Phng th nghim Cng ngh Lc Ha du

v Vt liu Xc tc trng i hc Bch khoa H Ni.

2.2.3. Phng php hp ph xung CO

y l phng php xc nh phn tn ca mt s kim loi trn b mt xc

tc v kch thc cc phn t hot ng trn c s: o lng kh CO hp ph ln

kim loi trn b mt ca mu phn tch (trong trng hp ny l Pd) v t tnh

c s phn b kim loi trn b mt cht mang.

Trong nghin cu ny, phn tn ca cc tm kim loi trn cht mang c

xc nh bng phng php hp ph xung CO iu kin nhit 350oC, lu



26/52


lng dng CO/Ar 10% l 10ml/pht trn thit b Autochem II ca hng

Micromeritic.

2.2.4. Phng phpTEM [1]

nghin cu c trng phn b v kch thc cc tm kim loi ca xc tc,

em s dng k thut hin vi in t truyn qua (transmission electron

microscopy - TEM).

Knh hin vi in t truyn qua l mt thit b nghin cu vi cu trc vt rn,

s dng chm in t c nng lng cao chiu xuyn qua mu vt rn mng v s

dng cc thu knh t to nh vi phng i ln (c th ti hng triu ln),nh c th to ra trn mn hunh quang, phim quang hc, hay ghi nhn bng cc

my chp k thut s.

Ta bit rng knh hin vi quang hc s dng nh sng kh kin quan st

cc vt nh, do phn gii ca knh hin vi quang hc b gii hn bibc

sngnh sng kh kin, v khng th cho php nhn thy cc vt c kch thc rt

nh.

Mt in t chuyn ng vi vn tc v, s c xung lngp = m0.v, v n

tng ng vi mt sng cbc sng cho bi h thc de Broglie:

Ta thy rng bc sng ca in t nh hn rt nhiu so vi bc sng nh

sng kh kin nn vic s dng sng in t thay cho sng nh sng s to ra thitb c phn gii tt hn nhiu knh hin vi quang hc.

Cu to v nguyn l lm vic ca knh hin vi in t truyn qua:

* Sng phng in t.

http://vi.wikipedia.org/wiki/%C4%90i%E1%BB%87n_t%E1%BB%ADhttp://vi.wikipedia.org/wiki/Th%E1%BA%A5u_k%C3%ADnhhttp://vi.wikipedia.org/wiki/Quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/w/index.php?title=%C3%81nh_s%C3%A1ng_kh%E1%BA%A3_ki%E1%BA%BFn&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=%C4%90%E1%BB%99_ph%C3%A2n_gi%E1%BA%A3i&action=edit&redlink=1http://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/B%C6%B0%E1%BB%9Bc_s%C3%B3nghttp://vi.wikipedia.org/wiki/B%C6%B0%E1%BB%9Bc_s%C3%B3nghttp://vi.wikipedia.org/w/index.php?title=%C3%81nh_s%C3%A1ng_kh%E1%BA%A3_ki%E1%BA%BFn&action=edit&redlink=1http://vi.wikipedia.org/wiki/%C4%90i%E1%BB%87n_t%E1%BB%ADhttp://vi.wikipedia.org/wiki/V%E1%BA%ADn_t%E1%BB%91chttp://vi.wikipedia.org/wiki/Xung_l%C6%B0%E1%BB%A3nghttp://vi.wikipedia.org/wiki/S%C3%B3nghttp://vi.wikipedia.org/wiki/B%C6%B0%E1%BB%9Bc_s%C3%B3nghttp://vi.wikipedia.org/w/index.php?title=H%E1%BB%87_th%E1%BB%A9c_de_Broglie&action=edit&redlink=1http://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/%C4%90i%E1%BB%87n_t%E1%BB%ADhttp://vi.wikipedia.org/wiki/Th%E1%BA%A5u_k%C3%ADnhhttp://vi.wikipedia.org/wiki/Quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/w/index.php?title=%C3%81nh_s%C3%A1ng_kh%E1%BA%A3_ki%E1%BA%BFn&action=edit&redlink=1http://vi.wikipedia.org/w/index.php?title=%C4%90%E1%BB%99_ph%C3%A2n_gi%E1%BA%A3i&action=edit&redlink=1http://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/B%C6%B0%E1%BB%9Bc_s%C3%B3nghttp://vi.wikipedia.org/wiki/B%C6%B0%E1%BB%9Bc_s%C3%B3nghttp://vi.wikipedia.org/w/index.php?title=%C3%81nh_s%C3%A1ng_kh%E1%BA%A3_ki%E1%BA%BFn&action=edit&redlink=1http://vi.wikipedia.org/wiki/%C4%90i%E1%BB%87n_t%E1%BB%ADhttp://vi.wikipedia.org/wiki/V%E1%BA%ADn_t%E1%BB%91chttp://vi.wikipedia.org/wiki/Xung_l%C6%B0%E1%BB%A3nghttp://vi.wikipedia.org/wiki/S%C3%B3nghttp://vi.wikipedia.org/wiki/B%C6%B0%E1%BB%9Bc_s%C3%B3nghttp://vi.wikipedia.org/w/index.php?title=H%E1%BB%87_th%E1%BB%A9c_de_Broglie&action=edit&redlink=1http://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dc


27/52


Trong TEM, in t c s dng thay cho nh sng (trong knh hin vi

quang hc). in t c pht ra t sng phng in t. C hai cch to ra

chm in t:

Th nht l s dng ngun pht x nhit in t: in t c pht ra t mt

catt c t nng (nng lng nhit do t nng s cung cp cho in t ng

nng thot ra khi lin kt vi kim loi. Do b t nng nn sng pht x nhit

thng c tui th khng cao v n sc ca chm in t thng km. Nhng

u im ca n l rt r tin v khng i hi chn khng siu cao. Cc cht ph

bin dng lm catt l W, Pt, LaB6...

Th hai l s dng sng pht x trng (Field Emission Gun). Cc TEM s

dng nguyn l ny thng c vit l FEG TEM: in t pht ra t catt nh

mt in th ln t vo v th ngun pht in t c tui th rt cao, cng

chm in t ln v n sc rt cao, nhng c nhc im l rt t tin v i

hi mi trng chn khng siu cao.

* Cc h thu knh v lng knh.

V trong TEM s dng chm tia in t thay cho nh sng kh kin nn vic

iu khin s to nh khng cn l thu knhthy tinh na m thay vo l cc

thu knh t. Thu knh t thc cht l mt nam chm in c cu trc l mt cun

dy cun trn li lm bng vt liu t mm. T trng sinh ra khe t s c

tnh ton c s phn b sao cho chm tia in t truyn qua s c lch thch

hp vi tng loi thu knh. Tiu c ca thu knh c iu chnh thng qua t

trng khe t, c ngha l iu khin cng dng in chy qua cun dy. V

c dng in chy qua, cun dy s b nng ln do cn c lm lnh bng

nc hoc nitlng.

http://vi.wikipedia.org/wiki/%C4%90i%E1%BB%87n_t%E1%BB%ADhttp://vi.wikipedia.org/wiki/%C3%81nh_s%C3%A1nghttp://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/%C4%90%E1%BB%99ng_n%C4%83nghttp://vi.wikipedia.org/wiki/%C4%90%E1%BB%99ng_n%C4%83nghttp://vi.wikipedia.org/wiki/Kim_lo%E1%BA%A1ihttp://vi.wikipedia.org/wiki/Whttp://vi.wikipedia.org/wiki/Pthttp://vi.wikipedia.org/wiki/Lahttp://vi.wikipedia.org/wiki/Bhttp://vi.wikipedia.org/wiki/%C4%90i%E1%BB%87n_th%E1%BA%BFhttp://vi.wikipedia.org/wiki/%C4%90i%E1%BB%87n_t%E1%BB%ADhttp://vi.wikipedia.org/wiki/Th%E1%BA%A5u_k%C3%ADnhhttp://vi.wikipedia.org/wiki/Th%E1%BB%A7y_tinhhttp://vi.wikipedia.org/wiki/Nam_ch%C3%A2m_%C4%91i%E1%BB%87nhttp://vi.wikipedia.org/wiki/V%E1%BA%ADt_li%E1%BB%87u_t%E1%BB%AB_m%E1%BB%81mhttp://vi.wikipedia.org/wiki/Ti%C3%AAu_c%E1%BB%B1http://vi.wikipedia.org/wiki/T%E1%BB%AB_tr%C6%B0%E1%BB%9Dnghttp://vi.wikipedia.org/wiki/T%E1%BB%AB_tr%C6%B0%E1%BB%9Dnghttp://vi.wikipedia.org/wiki/C%C6%B0%E1%BB%9Dng_%C4%91%E1%BB%99_d%C3%B2ng_%C4%91i%E1%BB%87nhttp://vi.wikipedia.org/wiki/D%C3%B2ng_%C4%91i%E1%BB%87nhttp://vi.wikipedia.org/wiki/Nit%C6%A1http://vi.wikipedia.org/wiki/%C4%90i%E1%BB%87n_t%E1%BB%ADhttp://vi.wikipedia.org/wiki/%C3%81nh_s%C3%A1nghttp://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/%C4%90%E1%BB%99ng_n%C4%83nghttp://vi.wikipedia.org/wiki/%C4%90%E1%BB%99ng_n%C4%83nghttp://vi.wikipedia.org/wiki/Kim_lo%E1%BA%A1ihttp://vi.wikipedia.org/wiki/Whttp://vi.wikipedia.org/wiki/Pthttp://vi.wikipedia.org/wiki/Lahttp://vi.wikipedia.org/wiki/Bhttp://vi.wikipedia.org/wiki/%C4%90i%E1%BB%87n_th%E1%BA%BFhttp://vi.wikipedia.org/wiki/%C4%90i%E1%BB%87n_t%E1%BB%ADhttp://vi.wikipedia.org/wiki/Th%E1%BA%A5u_k%C3%ADnhhttp://vi.wikipedia.org/wiki/Th%E1%BB%A7y_tinhhttp://vi.wikipedia.org/wiki/Nam_ch%C3%A2m_%C4%91i%E1%BB%87nhttp://vi.wikipedia.org/wiki/V%E1%BA%ADt_li%E1%BB%87u_t%E1%BB%AB_m%E1%BB%81mhttp://vi.wikipedia.org/wiki/Ti%C3%AAu_c%E1%BB%B1http://vi.wikipedia.org/wiki/T%E1%BB%AB_tr%C6%B0%E1%BB%9Dnghttp://vi.wikipedia.org/wiki/T%E1%BB%AB_tr%C6%B0%E1%BB%9Dnghttp://vi.wikipedia.org/wiki/C%C6%B0%E1%BB%9Dng_%C4%91%E1%BB%99_d%C3%B2ng_%C4%91i%E1%BB%87nhttp://vi.wikipedia.org/wiki/D%C3%B2ng_%C4%91i%E1%BB%87nhttp://vi.wikipedia.org/wiki/Nit%C6%A1


28/52


Nguyn l ghi nh trng sng v trng ti trong TEM: L thu knh ghi

nhn chm in t u tin t mu vt v lun c iu khin sao cho vt s v

tr c kh nng ly nt khi phng i ca h c thay i.

* B phn ghi nhn v quan st nh.

Khc vi knh hin vi quang hc, TEM s dng chm in t thay cho ngun

sng kh kin nn cch quan st ghi nhn cng khc. quan st nh, cc dng c

ghi nhn phi l cc thit b chuyn i tn hiu, hot ng da trn nguyn l ghi

nhn s tng tc ca in t vi cht rn.

Mn hunh quang v phim quang hc: l dng c ghi nhn in t da trnnguyn l pht quang ca cht ph trn b mt. Trn b mt ca mn hnh, ngi

ta ph mt lp vt liu hunh quang. Khi in t va p vo mn hnh, vt liu s

pht quang v nh c ghi nhn thng qua nh sng pht quang ny. Cng tng

t nguyn l ny, ngi ta c th s dngphim nh ghi li nh v nh ban u

c lu di dngphim m bn v s c trng ra sau khi s dng.

http://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/Phimhttp://vi.wikipedia.org/w/index.php?title=Phim_%C3%A2m_b%E1%BA%A3n&action=edit&redlink=1http://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/Phimhttp://vi.wikipedia.org/w/index.php?title=Phim_%C3%A2m_b%E1%BA%A3n&action=edit&redlink=1


29/52


Hnh 5: Cu to my chp TEM.

S to nh trong TEM:

Xt trn nguyn l, nh ca TEM vn c to theo cc c ch quang hc,

nhng tnh cht nh ty thuc vo tng ch ghi nh. im khc c bn ca nh

TEM so vi nh quang hc l tng phn khc so vi nh trong knh hin vi

quang hc v cc loi knh hin vi khc. Nu nh nh trong knh hin vi quang hcc tng phn ch yu em li do hiu ng hp th nh sng th tng phn

ca nh TEM li ch yu xut pht t kh nng tn x in t.

2.2.5. Phng php FE SEM

http://vi.wikipedia.org/wiki/%C4%90%E1%BB%99_t%C6%B0%C6%A1ng_ph%E1%BA%A3nhttp://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/T%C3%A1n_x%E1%BA%A1http://vi.wikipedia.org/wiki/%C4%90%E1%BB%99_t%C6%B0%C6%A1ng_ph%E1%BA%A3nhttp://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/K%C3%ADnh_hi%E1%BB%83n_vi_quang_h%E1%BB%8Dchttp://vi.wikipedia.org/wiki/T%C3%A1n_x%E1%BA%A1


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1, 2. Thit b o & iu khin lu lng kh

3. Thit b bay hi nguyn liu TTCE

4. B trn

5. L gia nhit

6. ng phn ng

Hnh 6: S h phn ng vi dng hydro clo ha TTCE

Phn ng HDC TTCE c tin hnh p sut thng, trn h thng s

phn ng lm bng thp khng g. Xc tc th nghim t trung tm ng phn

ng (lm bng thch anh, di 500 mm, ng knh 5mm). Nhit vng phn ng

c iu khin bng l in, vi sai s 1OC, s dng thit b iu khin nhit

RKC C100 (Taiwan). Cc kh s dng cho phn ng v kh mang c kim sot

bng b iu khin lu lng Omega FMA 5400/5500.

Nguyn liu TTCEc gi 25 OC v a ti phn ng di dng hi bo

ha bi kh mang argon. Sn phm ca phn ng c phn tch trc tip bng sc

k kh (Trace GC Ultra - Italy), ct TR5 260E143P (Thermo Electron

Corporation) v detector FID c kh nng nhn bit cc hp cht hydrocacbon

cha clo vi nng > 1 ppm.

Cc thng s nghin cu qu trnh phn ng:

Lng xc tc: 50 mg.

Lu lng dng H2: 80 ml/pht (10%H2/Ar).

Lu lng dng Ar: 120 ml/ pht (99,99% Ar).

Nhit vng phn ng: 3000C.



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Trc khi phn ng, xc tc c hot ha 300 0C trong 3h bng dng kh

10%H2/Ar lu lng 80 ml/pht.

Ch phn tch sn phm bng sc k kh c a ra trong bng 5:

Bng 5: Ch o ca my sc k kh

Detector

FIDNhit 2500CKhng kh 130 ml/phtH2 40 ml/pht

N2 30 ml/pht

Ct Ct mao qun, ct Thermo TR-5 30x0.32mm ID x 0.25m film

L Nhit 400C

Thi gian 15 pht

Dng vo

C chia dngTc dng 54 ml/pht

Nhit 1500CT l chia dng 67

Kh mang 0,8ml/pht

Hot tnh xc tc c nh gi qua chuyn ha ca nguyn liu TTCE.

chuyn ha nguyn liu (C) c tnh theo cng thc:

chuyn ha C, % = 100 x

hay C % =100 x


S mol TTCE cp vo - S mol TTCE cha phn ng

S mol TTCE cp vo

S mol TTCE cp vo

S mol TTCE phn ng

S mol TTCE cp vo

S mol TTCE cp vo


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Do s mol TTCE trc v sau phn ng u t l vi din tch pic TTCE khi

phn tch trn sc k nn cng thc trn c thay bng:

C % = 100x

PHN 3


Din tch pic TTCE trc phn ng Din tch pic TTCE sauphn ng

Din tch pic TTCE trc phn ng

S mol TTCE cp vo


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KT QU V THO LUN

3.1. c trng cu trc ha l ca xc tc

3.1.1. c trng din tch b mt ring ca xc tc

Din tch b mt ring ca xc tc BM1 (100Pd/C*) xc nh theo phng

php Langmuir l 1181,29 m2/g, ng knh mao qun trung bnh tp trung 9,14

. ng ng nhit hp ph v nh hp ph ca vt liu c a ra trn hnh 7.

Hnh 7: ng ng nhit hp ph ca xc tc BM1

Nh vy, BM1 th hin ng ng nhit hp ph loi 1, khng xut hin

vng tr. iu ny chng t xc tc ny l vt liu vi mao qun.

3.1.2. Hm lng kim loi thc t



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Hm lng kim loi thc t a ln cht mang sau ngm tm c phn tch

bng phng php ICP AES. Kt qu a ra trn hnh 8.

Hnh 8:

So snh tng

hm lng kim

loi theo l

thuyt v thct

Hnh 8

cho thy hm lng kim loi theo l thuyt v theo thc t c s khc bit: Theo l

thuyt, tng hm lng hai kim loi bng 1% khi lng xc tc nhng thc t cc

mu xc tc tng hp c tng hm lng hai kim loi thp hn d kin. Nh

vy, qu trnh ngm tm kim loi ln cht mang mi ch t hiu qu khong 90%.

S sai khc ny c th do qu trnh tng hp xc tc cha chnh xc, hoc do

cc kim loi phn b khng ng u trn b mt cht mang C*.

3.1.3. phn tn kim loi

phn tn ca cc tm kim loi trn cht mang c xc nh bng phng

php o hp ph xung CO. Kt qu phn tn v ng knh hot ng trong xc

tc c a ra trn hnh 9 v 10:



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3.1.4. S phn b kim loi trn b mt xc tc theo phng php TEM

a) C* b) BM1 (100Pd/C*)

Hnh 11: S phn b kim loi trn b mt xc tc

So snh kt qu TEM ca hai mu: cht mang C* n thun v BM1

(100Pd/C*) ta nhn thy: khi tm Pd ln cht mang C*, trn b mt than xut hin

cc ht kim loi, phn b tng i ng u. Chnh cc ht ny l tm hot tnh

ca xc tc, c vai tr hp ph H nguyn t, hp ph TTCE xy ra phn ngHDC.

3.1.5. S phn b kim loi trn b mt xc tc theo phng php FE SEM



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a) BM1 (100Pd/C*)

b) BM5 (100Fe/C*) c) BM9 (100Ni/C*)

Hnh 12: S phn b n kim loi trn cht mang C*Cng trn mt b mt cht mang, cng phng i 150000 ln, mu cha

kim loi khc nhau, ta quan st thy: Tm kim loi Pd ln C* cho xc tc c bmt mn v ng u; tm kim loi Fe ln C* ta c xc tc c b mt mp m,nhiu gc cnh, v tng i ng u; tm kim loi Ni ln C* ta c xc tc c

b mt khng ng u, c s phn bit cc cm kim loi to nh khc nhau.

Mt khc, khi so snh s phn b kim loi trn b mt xc tc n kim loi

Pd (BM1) v lng kim loi Pd-Fe (BM3), Pd-Ni (BM6) ta c kt qu nh trnhnh 13:



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a) BM1 (100Pd/C*)

b) BM 3 (50Pd 50Fe/C*) c) BM6 (75Pd 25Ni/C*)

Hnh 13: S phn b kim loi trong mu xc tc lng kim loi

Khi c mt kim loi th hai (Fe, Ni) vo hp phn xc tc Pd/C*, ta thy b

mt xc tc thay i. Fe lm cho b mt xc tc khng cn trng mn, to ra cc

ht ti xp bm trn b mt cht mang C*. Cc m Pd b phn tn thnh cc ht

ri nhng vn tn ti dng m ln. Mt khc, khi c mt kim loi Ni vo hpphn xc tc Pd/C*, xc tc c s kt ht to nh khc nhau v c s phn bin ht

r rng. Ni lm cho b mt xc tc khng cn trng mn, cc m trng Pd tch

ri hn, l ra nn en ca cht mang C*.



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3.2. Hot tnh xc tc Pd-Me/C*

3.2.1. Hot tnh xc tc ca cc mu n kim loi Me/C*

Kt qu th nghim trn cc mu ch cha Pd, Fe hoc Ni 1% khi lngc a ra trn hnh 14.

Hnh 14: chuyn ha TTCE theo thi gian phn ng trn cc mu xc tc Me/ C*

Quan st hnh 14 ta thy: Mu BM1 (100 Pd/C*) cho chuyn ha cao nht trong 3

mu, gi tr cao nht t khong 65%, hai mu cn li t chuyn ha thp hn, cao nht

ch t 51% v 41%. Tuy nhin, c 3 mu ny u th hin s mt hot tnh nhanh chng,

sau 90 pht th hot tnh cn li khong 30% v sau 180 pht hot tnh ca BM5 v BM 9

cn li khong 15%, thm ch hot tnh ca BM 1 ch cn li 2% . iu ny th hin rng

xc tc n kim loi c kh nng kh clo ca TTCE nhng cha n nh, c bit xc tc

n kim loi qu b mt hot tnh nhanh hn nhiu so vi cc kim loi khc. c im nys ngn cn vic trin khai xc tc trn quy m ln v thi gian lm vic ca xc tc qu

ngn.



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3.2.2. Hot tnh xc tc lng kim loi Pd-Fe/C*

nghin cu nh hng ca hp phn Fe n xc tc Pd/C*, h xc tc Pd-

Fe/C* c th nghim phn ng, kt qu a ra trn hnh 15.

Hnh 15: chuyn ha TTCE theo thi gian phn ng trn cc mu xc tc Pd-Fe/ C*

T hnh 15 ta thy: Khi thm Fe vo hp phn xc tc th chuyn ha cc i

tng khng ng k nhng n nh ca xc tc c th duy tr mc 30% (BM3),y l mt u th ln nu so snh vi mu BM1 ch cha n thun Pd/C*,

chuyn ha gim xung cn 2% sau thi gian phn ng 3h. Trong s cc t l Fe b

sung, 50% Fe (BM3) th hin kh nng duy tr hot tnh xc tc tt nht.

3.2.3. Hot tnh xc tc lng kim loi Pd-Ni/C*

nghin cu nh hng ca hp phn Ni n xc tc Pd/C*, h xc tc Pd-

Ni/C* c th nghim phn ng, kt qu a ra trn hnh 16.



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Hnh 16: chuyn ha TTCE theo thi gian phn ng trn cc mu xc tc Pd - Ni/ C*

T hnh 16 ta thy: Khi thm kim loi Ni vo, chuyn ha khng tng

nhng hot tnh c phn n nh hn nhiu. ng biu din chuyn ha ph

thuc vo thi gian phn ng c xu hng i ngang v duy tr mc 30-40% (mu

BM6). Nh vy vic b sung Ni ch yu c tc dng duy tr n nh hot tnh xc

tc v t l 25% Ni th hin kh nng h tr tt nht.

Nhn xt:

Trong 2 b xc tc Pd-Fe/C* v Pd-Ni/C*, ta nhn thy hai mu BM3 v

BM6 l xc tc tt nht. C hai kim loi Ni v Fe u gp phn tng tnh n nh

hot tnh ca xc tc, ngoi ra, kim loi Fe cn c tc dng lm tng hot tnh xc

tc.

T y ta tip tc nghin cu nh hng ca th t tm kim loi n hot tnh

xc tc. Vi BM3 v BM6, th t tm kim loi khi tng hp xc tc l tm ng

thi Pd v kim loi th hai (Fe, Ni). Em tng hp thm cc mu xc tc mi c th

t tm nh trong bng 6 nhm kho st c trng phn tn kim loi v

chuyn ha ca cc mu xc tc ny.



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Bng 6: Cc mu xc tc mi tng hp

K hiu Thnh phn Th t tm K hiu Thnh phn Th t tm

BM3 50Pd 50Fe/C* Tm ngthi

BM6 75Pd 25Ni/C* Tm ngthi

BM3 Pd 50Pd 50Fe/C* Tm Pd

trc

BM6 Pd 75Pd 25Ni/C* Tm Pd

trc

BM3 Fe 50Pd 50Fe/C* Tm Fe

trc

BM6 Ni 75Pd 25Ni/C* Tm Ni

trc

3.2.4 c trng phn tn kim loi khi thay i th t tm

Hnh 17: phn tn kim loi khi thay i th t tm

Hnh 17 cho thy khi thay i th t tm kim loi th b mt xc tc c thay i

theo. phn tn cao nht th hin trn mu 50Pd-50Fe/C* tm ng thi v mu

75Pd-25Ni/C* tm ng thi. Mu 75Pd-25Ni/C* tm Ni trc cng cho phn

tn tng i tt.



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Hnh 18: ng knh hot ng ca xc tc khi thay i th t tm

Hnh18 cho thy ng knh ht hot ng ca xc tc khc nhau khi thay i

th t tm. Ta nhn thy mu no c phn tn tm kim loi cao th tng ng

vi ng knh ht hot ng cng b (mu 50Pd 50Fe/C* tm ng thi c ng

knh ht hot ng l 11,04 nm). Ngc li, mu no c phn tn kim loi thp

th ng knh ht hot ng s cao, v d mu 75Pd 25Fe/C* tm Pd trc c

ng knh ht hot ng l 483,35nm.iu ny chng t rng c cc tm hot

ng b, ta nn tm hai kim loi ng thi vi nhau.

3.2.5. c trng phn b kim loi trn b mt xc tc khi thay i th t tm

(phng php FE SEM)

Hnh nh th hin c trng phn b kim loi trn b mt xc tc ca cc mu Pd-

Fe/C* v Pd-Ni/C* khi thay i th t tm, xc nh theo phng php FE SEM

nh sau:



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a) 50Pd 50Fe/C* tm ng thi b)50Pd 50Fe/C* tm Fe trc c) 50Pd 50Fe/C* tm Pd trc

Hnh 19: S phn b kim loi trn b mt cht mang ca xc tc 50Pd 50Fe/C* khithay i th t tm

Quan st hnh 19 ta nhn thy: khi thay i th t tm th b mt xc tc c

thay i theo. Vic tm ng thi Pd v Fe to ra nhiu tm kim loi nh hn v

ng u hn so vi tm ring bit.

a) 75Pd 25Ni tm ng thi b) 75Pd 25Ni tm Ni trc c) 75Pd 25Ni tm Pd trc

Hnh 20: So snh s phn b kim loi trn b mt cht mang ca xc tc 75Pd25 Ni/C* khi thay i th t tm.

Hnh 20 cho thy vic tm Ni trc s to ra nhiu tm hot tnh nh trn b

mt xc tc. Xc tc 75Pd 25Ni tm Pd trc hoc tm ng thi lm cho cc tm

kim loi phn b khng u v rng bng mu tm Ni trc.



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3.2.6. chuyn ha xc tc khi thay i th t tm

a. Hot tnh xc tc 50Pd-50Fe/C* khi thay i th t tm

Hnh 21: chuyn ha TTCE theo thi gian phn ng trn cc mu xc tc

50Pd-50Fe/ C* thay i th t tm

T hnh 21 ta thy: Khi thay i th t tm kim loi ln cht mang, hot tnh xc

tc cng thay i. BM3 v BM3 Pd cho chuyn ha cao, gi tr cc i t 67%.Tuy nhin, hot tnh ca BM3 Pd km n nh, sau 135 pht phn ng th chuyn

ha ch cn trn 10%. Mu BM3 Fe c chuyn ha thp hn mt cht, gi tr cao

nht t 59%, nhng n nh hn. Sau 180 pht phn ng, chuyn ha ca BM3

v BM3 Fe vn gi mc xp x 30% .

Nh vy, i vi cc mu xc tc Pd-Fe/C*, tm Fe trc hoc tm ng thi th

th chuyn ha cao v n nh hn, tm Pd trc th chuyn ha cao nhng kmn nh.



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b. Hot tnh xc tc 75Pd-25Ni/C* khi thay i th t tm

Hnh 22:

chuyn ha

TTCE theo thi

gian phn ng

trn cc mu xc

tc 75Pd-

25Ni/ C* thay

i th t tm

T hnh 22 ta thy: Khi thay i th t tm kim loi ln cht mang, hot tnh xc

tc cng thay i r rt. BM6 Ni cho chuyn ha cao hn hn BM6 v BM6 Pd.

chuyn ha cao nht ca BM6 Ni t trn 75%, sau n nh khong 50%.

chuyn ha cao nht ca BM6 t 60% sau n nh khong 30-40%. Mu BM6

Pd cho chuyn ha thp, cao nht ch t 47% v sau 45 pht cn di 30%.

Nh vy i vi Pd-Ni/C*, tm Ni trc th chuyn ha cao v n nh hn

so vi tm Pd trc hoc tm ng thi.



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KT LUN

T cc kt qu nghin cu xc tc Pd-Me/C* cho phn ng HDC TTCE, em

rt ra kt lun:

1. Vic a kim loi th hai vo hp phn xc tc Pd/C* c tc dng lm tng

phn tn kim loi ny trn b mt cht mang.

2. Cc kim loi th hai Fe, Ni ch yu lm tng n nh ca hot tnh xc

tc. Ngoi ra, Fe gp phn lm tng hot tnh ca xc tc.

3. Vic thay i th t tm c nh hng n hot tnh xc tc: Vi Pd-Fe/C*

tm ng thi hai kim loi, v vi Pd-Ni/C* tm Ni trc s t hiu qu hot tnh

xc tc cao v duy tr n nh nht.

Nhng kt qu trn cho thy, hng nghin cu tip theo nn tp trung vo

vic iu chnh t l cc kim loi ph tr nh Fe, Ni to ra xc tc a kim loi

Pd, Fe, Ni c hot tnh xc tc v n nh lm vic tt nht cho qu trnh HDC

x l cc hp cht clo hu c.



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TI LIU THAM KHO

1. http://en.wikipedia.org

2. http://www.eurochlor.org

3. Salvador Ordez, Fernando V. Dez, Herminio Sastre , Characterisation

of the deactivation of platinum and palladium supported on activated carbon used

as hydrodechlorination, catalysts Applied Catalysis B: Environmental 31 [2001]

113122.

4. Ruben F. Bueres, Esther Asedegbega-Nieto, Eva Daz, Salvador Ordonez, Fernando V. Dez, Performance of carbon nanofibres, high surface area

graphites, and activated carbons as supports of Pd-based hydrodechlorination

catalysts, Catalysis Today [2009]

5. Ruben F. Bueres, Esther Asedegbega-Nieto, Eva Daz, Salvador Ordez ,

Fernando V. Dez, Preparation of carbon nanofibres supported palladium catalysts

for hydrodechlorination reactions, Catalysis Communications 9 [2008] 208020846. Neil C. Concibido, Tetsuji Okuda, Yoichi Nakano,Wataru Nishijimab and

Mitsumasa kadaa, Enhancement of the catalytic hydrodechlorination of

tetrachloroethylene in methanol at mild conditions by water addition, Tetrahedron

Letters 46 [2005] 36133617

7. Ozer Orbay , Song Gao , Brian Barbaris , Erik Rupp , A. Eduardo Saez,

Robert G. Arnold , Eric A. Betterton, Catalytic dechlorination of gas-phaseperchloroethylene under mixed redox conditions, Applied Catalysis B:

Environmental 79 [2008] 4352

http://en.wikipedia.org/http://www.eurochlor.org/http://en.wikipedia.org/http://www.eurochlor.org/


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8. E.V. Golubina, E.S. Lokteva, V.V. Lunin, N.S. Telegina, A.Yu. Stakheevb, P.

Tundo, The role of Fe addition on the activity of Pd-containing, catalysts in

multiphase hydrodechlorination, Applied Catalysis A: General 302 (2006) 3241

9. Wataru Nishijima, Yusuke Ochi, Tsung-Yueh Tsai, Yoichi Nakano,

Mitsumasa Okada, Catalytic hydrodechlorination of chlorinated ethylenes in organic

solvents at room temperature and atmospheric pressure, Applied Catalysis B:

Environmental 51 (2004) 135140

10. Anna S rebowata , Wojciech Juszczyk , Zbigniew Kaszkur , Janusz W.

Sobczak, Leszek Kepinski, Zbigniew Karpinski, Hydrodechlorination of 1,2-

dichloroethane and dichlorodifluoromethane over Ni/C catalysts: The effect of

catalyst carbiding, Applied Catalysis A: General 319 (2007) 181192

11. J.R. Gonzlez-Velasco, A. Aranzabal, R. Lpez-Fonseca, R. Ferret, J.A.

Gonzlez-Marcos, Enhancement of the catalytic oxydation of hydrogen-lean

chlorinated VOCs in the presence of hydrogen-supplying compounds, Applied

Catalysis B: Environmental 24 (2000) 3343

12. Salvador Ordez, Herminio Sastre, Fernando V. Dez, Characterisation and

deactivation studies of sulfided red mud used as catalyst for the hydrodechlorination

of tetrachloroethylene, Applied Catalysis B: Environmental 29 (2001) 263273

13. David R. Luebke, Lalith S. Vadlamannati, Vladimir I. Kovalchuk, Julie L.

dItri, Hydrodechlorination of 1,2-dichloroethane catalyzed by PtCu/C: effect of

catalyst pretreatment, Applied Catalysis B: Environmental 35 (2002) 211217

14. M. Legawiec-Jarzyna, A. Srebowata, W. Juszczyk, Z. Karpinski,

Hydrodechlorination over PdPt/Al2O3 catalysts A comparative study of chlorine

removal from dichlorodifluoromethane, carbon tetrachloride and 1,2-dichloroethane,

Applied Catalysis A: General 271 (2004) 6168



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and relationships with catalytic activity in PdCu/SiO2 cogelled xerogel

catalysts, Applied Catalysis A: General 270 (2004) 201208

23. Tadeusz Janiak, Janina Okal, Effectiveness and stability of commercial

Pd/C catalysts in the hydrodechlorination of meta-substituted chlorobenzenes,

Applied Catalysis B: Environmental 92 (2009) 384392

24. S. Ordez, F.V. Dez, H. Sastre, Hydrodechlorination of

tetrachloroethylene over sulfided catalysts: kinetic study, Catalysis Today 73

(2002) 325331

25. Salvador Ordez, Herminio Sastre, Fernando V. Dez,

Hydrodechlorination of aliphatic organochlorinated compounds overcommercial hydrogenation catalysts, Applied Catalysis B: Environmental 25

(2000) 4958

26. Misael Martino, Roberto Rosal, Herminio Sastre, Fernando V. Dez,

Hydrodechlorination of dichloromethane, trichloroethane, trichloroethylene

and tetrachloroethylene over a sulfilded Ni/Mog-alumina catalyst, Applied

Catalysis B: Environmental 20 (1999) 301307

27. S. Ordez, H. Sastre, F.V. Dez, Hydrodechlorination of

tetrachloroethylene over modified red mud: deactivation studies and kinetics,

Applied Catalysis B: Environmental 34 (2001) 213226

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