Catalyst for hydrogen steam reforming flow

Steam reforming

1. Steam reforming of ethanol on Pt/Al
2O
3
catalyst

2. WHO NEEDS HYDROGEN?
http://www.afyren.com/contexte-et-enjeux-economiques-du-marche-hydrogene
Ammonia
49%
Methanol
8%
Refinery
37%
Industrial gas
4%
Aerospace
2%

3. TECHNOLOGIES FOR OBTAINING HYDROGEN
The technology of obtaining Advantages Disadvantages
Electrolysis
-Youcanusetheexcess
electricityfrompowerplants
-Youcanusesolarenergy
-Oxygenisalsoproducedand
canbeusedinvariousbranches
ofindustry
-Producepurehydrogen
-highenergyconsumption
-highcosts
-theneedforhightemperature
From fossil fuels
-Isawellestablishedmethod
-Showsavarietyofmethods
-Themostcosteffectivemethodof
economicandenergy(relatively
lowcost)
-Somemethodsrequirehigh
temperaturesandcontainlarge
amountsofimpuritiesinthegas
formed(majorpollution)
From biomass -Highefficiency
-Gasificationtakesplacealmostbyitself
-Thecheapestmethod
-generates carbon dioxide

4. HYDROGEN BY STEAM REFORMING OF ETHANOL
Table 1. The performance of catalysts in the reforming process
Catalytic system
Ni/Al
2
O
3
Ni/Mg/Al
NiMg6
Co/Al
2
O
3
Ni/Al
2
O
3
∙SiO
2
Cu
-
Ni/Al
2
O
3
Rh/Al
2
O
3
Ni/CeO
2
-
ZrO
2
dopat Co
Ni/ZnAl
2
O
4
-
Zr
Work conditions
Temperature 673K 923 K 673 K 673K 873K 973K 873K 923K
Pressure 1 atm 1 atm 1 atm 1 atm 1 atm1 atm1 atm 1 atm
GHSV/WHSV
/LHSV
H
2O/etanol=37500 h
-1
W/F =0.45
(gs)/cm
3
8.0 ml g
1
h
-1
12.7 h
-1
10.000
h
-1
W/F
A0=4.
06
gcat.h.mol
-1
W/F
et=49
gmin
-1
mol
Weight catalyst 125 mg 0.2 ml 0.3 g 150 mg 315 mg0.3 g100 mg 50 mg
% activemetal 1.2% Ni 14% Ni
(Ni/Mg
=1/6)
7.4% Co 30% Ni 2% Cu
14% Ni
1% Rh5% Co
30% Ni
10% Zr
7% Ni
Ethanol conversion% 79-97% 100% 100% 100% 99.2%100% 96.2% 3%
Selectivity%
Yield%
H
2 10-23% 64.9% 67% 58.7% 50.1%73.6%75.5 % 9.6%
CH
4 3-9% 2.1% 6% 17.8% 9.9% - 22.3% 5.1%
CO
2
CO
24-27%,
1-5%
20.2%,
12.8%
19%,
7.9%
38%, 32.4% 38%,
32.4%
20.3%,
6.1%
42.9%,
22.8%
18.5%,
23.5%
Hung,C.C.,Chen,S.L.,Liao,Y.K.,Chen,C.H.,Wang,J.H.,OxidativesteamreformingofethanolforhydrogenproductiononM/Al
2
O
3
,InternationalJournalofHydrogenEnergy,37,2012,p.
4955-4966.
Li,M.,Wang,X.,Li,S.,Wang,S.,Ma,X.,HydrogenproductionfromethanolsteamreformingovernickelbasedcatalystderivedfromNi/Mg/Alhydrotalcite-likecompounds,InternationalJournal
ofHydrogenEnergy,35,2010,p.6699-6708.
Haga,F.,Nakajima,T.,Miya,H.,Mishima,S.,Catalyticpropertiesofsupportedcobaltcatalystsforsteamreformingofethanol,CatalysisLetters,48,1997,p.223-227.

5. CATALYST CHARACTERIZATION
Techniques
of
characterizatio
n
X-ray Diffraction
X-ray
photoelectro
n
spectroscop
y
Thermogravimetric
analysis
Isotherms
adsorption /
desorption

6. THERMOGRAVIMETRICANALYSIS
Figure5.ThethermogravimetricanalysisforPt/Al
2O
3catalyst.
ForPt/Al
2O
3catalyst,thecurvesobtainedshowedthatthetotalweightlossoccursin
differenttemperatureregions.Thefirstregionoccursfromaboutroomtemperaturetoabout
82.70
0
C,andcorrespondstoremoveallorganicsolvent,andphysisorbedwater.Massloss
forthesecondregionstartsat188.71
0
Cto533.67
0
C.Thislosswasattributedtotheremoval
ofwaterpresentinthestructureofthesupport:
AlO(OH)xnH
2
O→AlO(OH)+nH
2
O
2AlO(OH)→Al
2
O
3
+H
2
O

7. 300
0
C
350
0
C
400
0
C
450
0
C
500
0
C
Experimental parameters
CATALYTICTEST

8. Ethanol 5%, w=3h
-1
Ethanol 5%, w=9h
-1
Ethanol 5%, w=15h
-1
Temperature Pt/Al
2O
3 Pt/Al
2O
3 Pt/Al
2O
3
300
0
C 70.37 58.91 41.00
350
0
C 75.47 72.77 40.12
400
0
C 82.67 77.12 57.53
450
0
C 89.21 89.13 89.11
500
0
C 96.54 93.33 90.59
Ethanol 10%, w=3h
-1
Ethanol 10%, w=9h
-1
Ethanol 10%, w=15h
-1
Pt/Al
2O
3 Pt/Al
2O
3 Pt/Al
2O
3
300
0
C 70.37 69.13 51.60
350
0
C 77.36 75.30 58.52
400
0
C 78.60 78.15 59.00
450
0
C 90.24 80.00 73.33
500
0
C 92.83 90.12 87.48
Ethanol 15%, w=3h
-1
Ethanol 15%, w=9h
-1
Ethanol 15%, w=15h
-1
Pt/Al
2O
3 Pt/Al
2O
3 Pt/Al
2O
3
300
0
C 67.87 66.94 65.87
350
0
C 77.68 69.22 69.19
400
0
C 78.51 73.97 71.94
450
0
C 89.81 82.50 78.51
500
0
C 91.43 85.83 84.62
Table 4. Ethanol conversion obtained under the experimental plan (p = 1 atm).

9. Temperature Ethanol 5%, w=3h
-1
Ethanol 5%, w=9h
-1
Ethanol 5%, w=15h
-1
Pt/Al
2O
3 Pt/Al
2O
3 Pt/Al
2O
3
300
0
C 27.39 26.03 24.86
350
0
C 22.58 21.01 16.35
400
0
C 16.70 15.30 13.20
450
0
C 11.50 10.20 6.21
500
0
C 9.30 4.30 2.13
Etanol 10%, w=3h
-1
Etanol 10%, w=9h
-1
Ethanol 10%, w=15h
-1
Pt/Al
2O
3 Pt/Al
2O
3 Pt/Al
2O
3
300
0
C 34.83 27.39 23.05
350
0
C 30.77 22.58 16.64
400
0
C 27.10 17.67 15.27
450
0
C 20.17 13.84 8.56
500
0
C 13.40 6.74 4.40
Ethanol 15%, w=3h
-1
Ethanol 15%, w=9h
-1
Ethanol 15%, w=15h
-1
Pt/Al
2O
3 Pt/Al
2O
3 Pt/Al
2O
3
300
0
C 36.89 32.00 18.08
350
0
C 34.02 30.96 17.92
400
0
C 33.69 30.47 16.37
450
0
C 29.16 25.75 14.90
500
0
C 25.80 20.40 10.81
Table 5. H
2yield obtained according to the experimental plan (p = 1atm).

10. CONCLUSIONS
-Bioethanolreformingtakesplacethroughacomplicatedreactionmechanismwhich
includesanumberofintermediatereactionswhichethanolisdecomposedwiththe
formationofH
2,CH
4andCO2,isdehydrogenatedordehydratedwiththeformationof
acetaldehydeandethylenerespectively.
-Themechanismoftheadsorptionreactionofreformingofethanolisasingleactive
centerformationchemosorbspeciesoftype1-hydroxyethylorpreferentialbreaking
ethoxide,followedbythereleaseoftheOHandhydrogen.
-Pt-basedcatalystspromotethedehydrationreactionthatgeneratesC
2H
4.Ethylenecan
beconvertedtoH
2byreformingreactionbutalsoacatalystofPt,veryactiveinthe
hydrogenationreactioncanbesaturatedtoethaneusinguphydrogenform.
-Increasingthereactiontemperaturelowerstheyieldofhydrogenasaresultof
increaseddehydrationreactionofthealcoholwiththeformationofethylenewhich
consumesapartofthehydrogenproduced.
-Thealuminasupportethanolconversionisbetter,buttheyieldofhydrogenislow
becausetheyarepromotedthedehydrationreactionwhichconsumeshydrogento
ethyleneinethanesaturation.
-Al
2O
3supportwhichhashigheraciditycomparedtoothersupportusedinethanol
dehydrationtoethylenewillincrease,butduetoitssaturationbyhydrogenationleadsto
thelowerhydrogenyields.

11. -Withweighthourspacevelocity​​increasesthehydrogenyielddecreasesasjustifiedby
theinfluenceofreactiontimeonthereactionkineticswhichisdoneinseveralsteps:
dehydrogenationanddehydrationfollowedbyreformingreactionsorbythereactionof
COShiftconversiontoCO
2andH
2orbyreactionofsaturatedorpolymerizationof
ethylene.Intermsofthefirststagethereactionkineticsareslower.
-Atanyvalueweobtainedagreaterhydrogenproductionwhentheethanolcontentof
thefeedstockwashigher.
-Higheryieldsofhydrogenobtainedatdilutionsofethanolreformingcatalystsystems
proposedpresentsagreateconomicadvantage,becauseitallowsthesafeuseofthebio-
ethanolfromfermentationwithoutconcentrationwhichinvolvesexpensiveoperation.
-ThehigherethyleneselectivityofthecatalystssupportedonAl
2O
3isduetothehigher
acidityofthesupportascomparedtoothersupportused,whichwillhavetheeffectof
increasingtheethanoldehydrationreactiontoformethylene.