Valorisation of char residues from biomass gasifjcation in - - PowerPoint PPT Presentation

Heraklion, 27.06.2019

Valorisation of char residues from biomass gasifjcation in adsorption applications

• V. Benedetti, E. Cordioli, F

. Marchelli, F . Patuzzi, M. Baratieri

Background

Biomass gasifjcation

• Gas
• T

ar (liquid)

• Char

(solid) South T yrol: about 1300 tons/year

• f char disposed of as industrial

waste with a high cost for disposal (140 - 150 €/ton) Valorization

Background

Char valorization at UNIBZ

Catalysis Adsorption Agriculture Tar removal

CO2 H2S

CO2 adsorption H2S adsorption

Outline

Other applications Char collection and characterization

CO2 adsorption H2S adsorption

Outline

Other applications Char collection and characterization

• Elemental analysis
• Physisorption analysis
• X-ray power difgraction

Characterization techniques

Feedsto ck Technology Electric power kWel Thermal power kWth T °C 1 Wood chips Dual-stage 50 110 ~900 2 Wood chips Dual-stage 280 540 ~850 3 Pellets Rising co- current 180 270 ~700 4 Wood chips Downdraft 150 260 ~650 5 Wood chips Downdraft 296 550 ~800 6 Wood chips Downdraft 45 120 ~650

Gasifjcation technologies

• Scanning electron microscopy
• Small angle X-ray scattering
• Thermogravimetric analysis
• V. Benedetti et al., Characterization of char

from biomass gasifjcation and its similarities with activated carbon in adsorption applications, Appl. Energy, 227 (2018) 92-99.

Difgerences among chars XRD

Q: quartz (SiO2), P: portlandite (Ca(OH)2), C: calcite (CaCO3), L: lime (CaO)

SEM

Sampl e C %wtd

ry

H %wtd

ry

N %wtd

ry

S %wtd

ry

O %wtd

ry

Ash %wtd

ry

CHAR1 81.1 3 0.23 0.28 0.35 3.74 14.6 2 CHAR2 91.3 9 0.72 0.26 0.57 3.43 4.20 CHAR3 81.1 7 0.25 0.61 0.27 1.89 16.0 8 CHAR4 48.1 2 0.49 0.23 0.32 1.64 49.5 2 CHAR5 80.6 4 0.55 0.22 0.20 2.79 15.8 CHAR6 68.6 3 0.33 0.83 0.32 2.05 27.8 4

Elemental analysis (% wtdry) Surface area

SBET pore size pore volume m2/ g nm cm3/g CHAR 1 603 3.88 0.30 CHAR 2 297 4.50 0.26 CHAR 3 403 4.70 0.50 CHAR 4 183 4.90 0.25 CHAR 5 427 4.40 0.39 CHAR 6 352 4.54 0.24

1 2

• Highest surface area
• Low amount of ash
• High surface area
• Lowest amount of ash

ADSORPTION CATAL Y SIS

CO2 adsorption H2S adsorption

Outline

Other applications Char collection and characterization

Materials and methods

Adsorptiv e: Adsorben t: Thermo-gravimetric tests run in a Jupiter STA449-F3 (Netzsch)

• Tads = 50 - 75 - 100 °C
• CO2:N2 = 1:1 - 1:4
• KOH -

ZnCl2

• N2
• 600 °C
• 1 hour

CO2 5 pure chars 2 activated chars 2 AC

Results

• V. Benedetti et al., CO2 adsorption study on pure and

chemically activated chars derived from commercial biomass gasifjers, J. CO2 util., 33 (2019) 46-54.

Adsorption curves SEM images

1 2 3 4 5 AC 1 AC 2 1_KO H 1_Zn Cl2

Results

Efgect of T and gas composition

Sample Uptake, % N2 uptake, % CHAR1 3.49 0.20 CHAR2 3.04 0.14 CHAR3 2.09 0.08 CHAR4 1.69 0.65 CHAR5 2.75 0.17 AC1 3.01 0.10 AC2 2.13 0.07 CHAR1_K OH 3.73 0.35 CHAR1_Z nCl2 3.03 0.13

50 75 100 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 3,49 2,48 1,86 1,84 1,57 0,74 1:1 1:4 T emperature, °C Uptake, %

Activated char A C Pure char

CHAR1 Literatu re 2.50 - 10.70

Results - physisorption

0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 100 200 300 400 500 CHAR1 CHAR4 AC1 AC2 CHAR1_KOH CHAR1_ZnCl2 Relative pressure, p/p0 A m o unt adso rbe d, cm 3/g

Results - physisorption

100 200 300 400 500 600 700 800 900 1000 1100 1 2 3 4 SBET, m2/g Uptake, %

0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 100 200 300 400 500 CHAR1 CHAR4 AC1 AC2 CHAR1_KOH CHAR1_ZnCl2 Relative pressure, p/p0 A m o unt adso rbe d, cm 3/g

Results

Adsorption/desorption cycles to test loss of char adsorption capacity

CHAR1_KOH

10 110 210 310 410 510 610 710 810 910 1010 1110 95 97 99 101 103 time, min TG, %

1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 Adsorption cycle U p ta k e , %

• High selectivity
• High adsorption capacity
• Good adsorption/desorption kinetics
• Stable adsorption capacity after repeated

cycles

Efgective CO2 adsorbent

CO2 adsorption H2S adsorption

Outline

Other applications Char collection and characterization

Meterials and methods

Adsorptiv e: Adsorben t:

H2S 5 pure chars 2 AC

• Fixed bed reactor - quartz
• Char bed height: 2.5 cm (150 -

200 mg)

• H2S + N2: 100 NmL/min
• H2S: 250 ppm
• Tamb
• Micro-GC for gas analysis at the
• utlet

1 - Adsorption capacity

Meterials and methods

Adsorptiv e: Adsorben t:

H2S

• Fixed bed reactor - quartz
• Char bed height: 2.5 cm (150 -

200 mg)

• H2S + N2: 100 NmL/min
• H2S: 250 -550 -1000 ppm
• Tamb
• Micro-GC for gas analysis at the
• utlet

Best performing char

2 - Efgect of inlet concentration

Results

char-A char-B char-Cchar-D char-E AC-1 AC-2 1 2 3 4 5 6 7 8 6,88 5,41 5,38 1,61 2,77 2,35 2,61

H2S adsorption capacity [mg/g]

Literature 1.71 - 65 mg/g AC 0.04 - 0.22 mg/g char from pyrolysis

F . Marchelli et al., Experimental study on H2S adsorption on gasifjcation char under difgerent operative conditions, Biomass Bioenergy 126 (2019) 106 - 116. 250 500 750 1000 1250 1500 1 2 3 4 5 6 7 8 Char surface area [m²/g] H 2 S a d s o r p t i o n c a p a c i t y [ m g / g ]

Efgect of surface area

Results

10 20 30 40 50 60 1 2 3 4 5 6 7 8 Ash content [%] H 2 S a d s o r p t i o n c a p a c i t y [ m g / g ]

Efgect of ash Metal content

char-A char-B char-C char-D char-E AC-1 AC-2 0,5 1 1,5 2 2,5 3 3,5 1 2 3 4 5 6 7 8 6,88 5,41 5,38 2,77 1,61 2,35 2,61 Oxygen mass fraction T

• tal metal mass fraction

SBET H₂S adsorbed amount H2S adsorbed amount (mg g-1)

Dimensionless oxygen and metal mass fraction, and SBET

Results

Efgects of:

• Oxygen content
• Metals mass fraction
• Surface area

Results - Efgect of concentration

10 20 30 40 50 60 70 80 90 100

Breakthrough curves

1000 ppm Time [min] H 2 S o u t l e t v o l u m e f r a c t i o n ( p p m ) 1000 800 600 400 200

Low concentrations slow down the process, but do not afgect the adsorption capacity

Inlet volume fraction of H2S, ppm H2S adsorption Capacity, mg g−1 250 6.88 ± 0.37 500 7.87 ± 0.70 1000 6.98 ± 0.24

CO2 adsorption H2S adsorption

Outline

Other applications Char collection and characterization

Char as catalyst support for Fischer- Tropsch synthesis

• V. Benedetti et al., Investigating the feasibility
• f

valorizing residual char from biomass gasifjcation as catalyst support in Fischer- T ropsch synthesis, under review.

CO conv., % Char, 10% Co 8 Char, 10% Fe 26 Literatur e 15 - 80

Products distribution

• V. Benedetti et al., Valorization of char from

biomass gasifjcation as catalyst support in dry reforming of methane, Front. Chem, 7 (2018) 119.

Char as catalyst support for Dry Reforming of Methane (DRM)

Tar removal by thermal and catalytic cracking

Model tar compounds:

• T
• luene
• Naphthalene
• Phenol

First stage

• Efgect of temperature 800-1000

°C

• Efgect of space velocity
• Efgect of tar concentration

Changing operating conditions Second stage Other gas mixtures/real tar from lab-scale gasifjer Evaluation of tar removal effjciency and analysis

• f

converted products (both condensables and gaseous)

Thank you for your attention

Valorisation of char residues from biomass gasifjcation in adsorption applications E-mail: vittoria.benedetti@unibz.it Website: https://bnb.groups.unibz.it/