Biomass gasification in supercritical water: II. Effect of catalyst

BIOMASS GASIFICATION IN BIOMASS GASIFICATION IN SUPERCRITICAL WATER: SUPERCRITICAL WATER:

EFFECT OF CATALYSTEFFECT OF CATALYST

Jale Yanik, S.Ebale*, A. Kruse*, M. Saglam, M. Yüksel

Department of Chemistry, Faculty of Science, Department of Chemistry, Faculty of Science, Ege University, 35100Ege University, 35100

Izmir,TurkeyIzmir,Turkey

*Institue for Technical Chemistry*Institue for Technical ChemistryDivision of ChemicalDivision of Chemical--Physical ProcessingPhysical ProcessingForschungszentrum Karlsruhe,GermanyForschungszentrum Karlsruhe,Germany

Objective of the investigation;

Hydrogen production from biomass by supercritical water gasification

Evulation of experimental findings with respect to:

- Product distribution

-Yields of major liquid products

- Gas product composition depending on:

biomass type

catalyst type

Gasification of Biomass in SCW

-Thermal Gasification

-Catalytic Gasification


Feed stock:

- agricultural wastes: tobacco stalk(B1), corn stalk (B2), cotton stalk(B3), sunflower stalk (B4), corncob(B5), oreganum stalk (B6)

- leather wastes: chromium- tanned(B7) waste and vegetable-tanned(B8) waste

Thermal Gasification


B1B1tobaccotobacco

B2B2corn stkcorn stk

B3B3cot. stkcot. stk

B4B4sun. stksun. stk

B5B5corncobcorncob

B6B6oreg.stkoreg.stk

Ash,%Ash,% 7.37.3 6.76.7 4.54.5 11.211.2 2.12.1 4.04.0

CC 40.6040.60 39.7039.70 42.2042.20 36.1036.10 42.9042.90 42.5042.50

Ultimate analysis, dry wt%Ultimate analysis, dry wt%

HH 5.705.70 5.905.90 6.006.00 5.305.30 6.406.40 6.006.00

NN 0.080.08 1.501.50 0.700.70 1.301.30 0.600.60 0.700.70

0.290.29

2.42.40.10.1--

SS 0.490.49 0.290.29 0.390.39 0.590.59 0.290.29

KK 7.57.5 3.53.5 2.92.9 7.97.9 5.25.2CaCa 3.43.4 0.90.9 0.70.7 4.94.9 1.41.4MgMg 0.10.1 0.10.1 0.10.1 0.20.2 0.20.2

Properties of lignocellulosic biomasses


B1B1tobaccotobacco

B2B2corn stkcorn stk

B3B3cot. stkcot. stk

B4B4sun. stksun. stk

B5B5corncobcorncob

B6B6oreg.stkoreg.stk

CelluloseCellulose 48.5 48.5 27.0 27.0 47.1 47.1 43.1 43.1 31.7 31.7 33.8 33.8

LigninLignin 11.111.1 3.03.0 11.011.0 9.7 9.7 3.4 3.4 9.39.3

HemicelluloseHemicellulose 16.2 16.2 27.1 27.1 13.113.1 7.4 7.4 31.731.7 10.910.9

Properties of lignocellulosic biomasses


B7B7chromiumchromium--

tannedtanned

B8B8vegetablevegetable--

tanned tanned Ash,%Ash,% 9.09.0 4.14.1

Ultimate analysis, dry wt%Ultimate analysis, dry wt%CC 37.237.2 46.2046.20

HH 6.406.40 5.505.50

NN 13.6013.60 6.606.60

SS 1.791.79 1.291.29

KK 0.10.1 0.9810.981CaCa 0.20.2 0.5920.592CrCr 4.44.4 nilnil

Properties of leather wastes


Batch Reactor- Autoclavewith 1 L of volume,

3 °C min-1

500 °C, 1 h

8.3 g of lignocellulosic or

1.6 g of leather wastes and

140 ml of water



MaterialsMaterials B1B1(tobac)(tobac)

B2B2(corns)(corns)

B3B3(cotton)(cotton)

B4B4(sunflow)(sunflow)

B5B5(cornc)(cornc)

B6B6(oreg)(oreg)

Max. Pressure, barMax. Pressure, bar 278.5278.5 335.8335.8 275.8275.8 308308 287.6287.6 241.2241.2ProductsProductsGas, Gas, (g gas/kg biomass)(g gas/kg biomass) 247247 534534 418418 592592 340340 390390

21.721.7Coke, Coke, (g coke/kg biomass)(g coke/kg biomass) 55.455.4 66.366.3 104.8104.8 19.319.3 113.3113.3

Product distribution from SCWG of agricultural wastes



Some parts of aromatic compounds such as lignin or other unsaturated species, are eventually polymerized to tar and char materials.



Although B6 and B4 have similar lignin content, the amount of coke obtained from B6 was five times more than that of from B4.Similarly, B3 gave two times more coke than that of from B4even their lignin contents were identical.

Coke formation in biomass gasification due to the lignin not only depends on the lignin amount and also strongly depends on the structure of lignin and interactions between other components in biomass.

MaterialsMaterials B7B7 B8B8

Max. Pressure, barMax. Pressure, bar 249.3249.3 314.5314.5ProductsProductsGas, Gas, (g gas/kg biomass)(g gas/kg biomass) 165165 519519

Coke, Coke, (g coke/kg biomass)(g coke/kg biomass) 175.0175.0 237.5237.5

Product distribution from SCWG of leather wastesThermal Gasification


B8 produced more amount of coke, because vegetable tannin agent consists of phenolic compounds.

4,65 4,12 4,13 3,65 2,094,09

1,444,05

02468

101214161820

B1 B2 B3 B4 B5 B6 B7 B8

Yiel

d, m

ol g

as/k

g bi

omas

s CH4CO2H2

Gas yields from different biomass feedstocks.



water–gas shift reaction CO + H2O⇋ CO2 + H2

methanation reaction CO + 3H2⇋ CH4 + H2O



Although B1 and B4 have similar potassium content as well as the cellulose, hemicellulose and lignin content, the yields and composition of gases obtained from B1 and B4 are significantly different from each other.

These findings indicate that organic materials other thancellulose, hemicellulose and lignin may have also effect theyield and composition of gas products



Proteins

The degradation of organic acid produce mainly CO, CO2, H2 and H2O



Amino acids

carbonic acids/amines

carboxylic acids/ammonia

cellulose

glucose/fructose

acids/aldehydes

gases

furfurals

phenols

higher molecular weight products

I II III

decomposition of cellulose in supercritical water


0

2

4

6

8

10

12

14

B1 B2 B3 B4 B5 B6 B7 B8

g liq

uid

prod

uct /

kg

biom

ass acetic acid

formic acidfurfuralsphenols

Yields of major products in aqueous phase from SCWGof different biomasses.



CONCLUSION



- The gasification of lignocellulosic and tannery wastesleads to formation of gases consisting of mainly H2,CO2 and CH4.

-The gas obtained from tobacco stalks contained the highest amount H2(39.47%), although it produced relatively lowgas yield.

-The lowest total gas yield was obtained from chromium tanned waste.

CONCLUSION

- tannery waste containing no chromium gave the similargas yields and composition with the lignocellulosic materials.

in the case of real biomass, the gasification reactions were more complex and the whole biomass contents are expected to effect on the results.



Catalysts: Red mud, Trona, Ni, K2CO3

Feedstock:- agricultural wastes: sunflower stalk, corncob

- leather wastes: vegetable-tanned

Catalytic Gasification


Red mud:Fe2O3 (37.72%), Al2O3 (17.27%), SiO2 (17.10%), TiO2 (4.81%), Na2O (7.13%), and CaO (4.54%).

Trona: Na3H(CO3)2.2H2O

Ranney nickel:(as suspension containing 50 wt% water and 50 wt% Raney nickel)



Batch Reactor- Autoclave with 1 L of volume,

3 °C min-1

500 °C, 1 h

8.3 g of biomass and 0.8 g of catalyst and 140 ml of water

(biomass-catalyst suspension -5 wt% biomass + 0.5 wt% catalyst-)



CatalystCatalyst nonenone KK22COCO33 TronaTrona Red MudRed Mud RaRa--NiNi

Max. Pressure, barMax. Pressure, bar 308308 311311 360360 314314 314314ProductsProductsGas, Gas, (g gas/kg biomass)(g gas/kg biomass) 592592 420.8420.8 461.06461.06 446.75446.75 477.3477.3

357.8357.8Coke, Coke, (g coke/kg biomass)(g coke/kg biomass) 19.319.3 90.290.2 160.2160.2 31.331.3

Product distribution from SCWG of sunflower stalks



Used catalysts promote the condensation reactions

0

5

10

15

20

25

none K2CO3 Trona Red mud Ra-Ni

yiel

ds, m

ol g

as /

kg b

iom

ass

CH4CO2H2

Gas yields from sunflower stalkCatalytic Gasification


- Hydrogen yields were extremely increased by using of catalysts.

- Trona showed similar activity with K2CO3 in hydrogen production.



K2CO3 + H2O ...........KHCO3 + KOH

KOH + CO ....... HCOOK

Formate reacts with water to produce hydrogen

HCOOK + H2O ..... KHCO3 + H2

CO2 is produced by the decomposition of KHCO3

2KCO3..............H2O + K2CO3 + CO2

However in this study

CO2 content decreased by using of catalyst

Reason may be

- CO2 may be consumed by the reaction with organic materials

- CO2 may partly be present in the liquid phase.



- CH4 formation was decreased to the same extent for all catalysts.

CH4 + 2H2⇋ CO2 + H2



0

2

4

6

8

10

12


g liq

uid

prod

uct /

kg

biom

ass

acetic acidformic acidfurfuralsphenols

Yields of major products in aqueous phase from SCWGof sunflower stalk



-The addition of alkaline catalysts increased the formic acid yield

• probably due to the formation of potassium formate

-The phenol amount was decreased by addition of catalyst.

• catalysts used enhanced the cross-linking reactions

between phenols and lower-molecular-weight fragments or

• suppressed the phenol formation.



CatalystCatalyst nonenone KK22COCO33 TronaTrona Red MudRed Mud RaRa--NiNi

Max. Pressure, barMax. Pressure, bar 287.6287.6 312.0312.0 317.0317.0 357.3357.3 403.1403.1ProductsProductsGas, Gas, (g gas/kg biomass)(g gas/kg biomass) 340340 614.9614.9 412.1412.1 426426 448.1448.1

28.928.9Coke, Coke, (g coke/kg biomass)(g coke/kg biomass) 21.721.7 21.721.7 40.940.9 16.916.9

Product distribution from SCWG of corncobCatalytic Gasification


catalysts led to an increase in gas yield where as no significant effect of catalyst on coke formation was observed.

0

5

10

15

20

25


yiel

ds, m

ol g

as /

kg b

iom

ass

CH4CO2H2

Gas yields from corncob



Trona showed the highest activity in both

water-gas shift reaction and reforming of methane.



0

5

10

15

20

25


g liq

uid

prod

uct /

kg

biom

ass


Yields of major products in aqueous phase from SCWGof corncob



The effect of catalyst on gasification varied according to the type of agricultural wastes. The differences is resulted from the composition of lignocellulosic materials.



-Sunflower stalk contained more amount of cellulose and much less amount of hemicellulose than corncob.

-Besides, the organic constituents other than cellulose and lignin might be different in each material.

CatalystCatalyst nonenone KK22COCO33 TronaTrona Red MudRed Mud

Max. Pressure, barMax. Pressure, bar 314314 309309 311311 299299ProductsProductsGas, Gas, (g gas/kg biomass)(g gas/kg biomass) 331.26331.26 411.8411.8 343.9343.9 322.5322.5

10.910.9Coke, Coke, (g coke/kg biomass)(g coke/kg biomass) 33.7333.73 50.9650.96 68.4368.43

Product distribution from SCWG of leather



Raney-Ni has very high gasification affect in SCWG of proteins.

Only K2CO3 considerably affected the gas yield.

0

5

10

15

20

25

none K2CO3 Trona Red mud

yiel

ds, m

ol g

as /

kg b

iom

ass

CH4CO2H2

Gas yields from leather



Proteins

The degradation of organic acid produce mainly CO, CO2, H2 and H2O



Amino acids

carbonic acids/amines

carboxylic acids/ammonia

0

1

2

3

4

5

6

7

none K2CO3 Trona Red mud

g liq

uid

prod

uct /

kg

biom

ass


Yields of major products in aqueous phase from SCWE of leather waste



• The amount of acetic acid decreased in presence of catalysts.

• Because the tanning agent in leather waste consists ofphenolic compounds, the phenols content in aqueous phase was increased by catalytic degradation of tanningagent.



In this study, the catalytic gasification of real biomasses (lignocellulosic and proteinous materials) in supercritical water was investigated.

Trona (a natural mineral) and red-mud (a by-product) were used as catalyst besides K2CO3 and Raney-Ni,

CONCLUSION



The effect of catalysts on gasification varied according to the type of biomass.

Catalysts have significantly increased the hydrogen yield. The all used catalysts enhanced the water-gas shift reaction and reforming of methane which due to the formation of H2 rather than methanation.



CONCLUSION

Trona showed similar gasification activity with K2CO3.

Although, the yield of hydrogen with red mud was lower than that with alkaline catalysts for all biomass tested, the present findings established that iron based catalysts show activity for the production of hydrogen from biomass.



CONCLUSION

As conclusion, SCWG of biomass in presence of red mud and trona is a promising method to produce H2 from biomass efficiently as well as gasification with commercial alkaline catalysts.



Biomass gasification in supercritical water: II. Effect of catalyst

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