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Valorisation of char residues from biomass gasifjcation in adsorption applications V. Benedetti, E. Cordioli, F . Marchelli, F . Patuzzi, M. Baratieri Heraklion, 27.06.2019

Background Biomass gasifjcation  Gas  T ar (liquid)  Char (solid) South T yrol: about 1300 tons/year of char disposed of as industrial waste with a high cost for disposal (140 - 150 €/ton) Valorization

Background Char valorization at UNIBZ Catalysis Agriculture CO 2 Adsorption Tar removal H 2 S

Outline Char collection CO 2 and characterization adsorption Other H 2 S applications adsorption

Outline Char collection CO 2 and characterization adsorption Other H 2 S applications adsorption

Gasifjcation technologies Feedsto Technology Electric Thermal T ck power power °C kW el kW th 1 Wood Dual-stage 50 110 ~900 chips 2 Wood Dual-stage 280 540 ~850 chips 3 Pellets Rising co- 180 270 ~700 current 4 Wood Downdraft 150 260 ~650 Characterization chips 5 Wood Downdraft 296 550 ~800 techniques   Elemental analysis Scanning electron microscopy chips   Physisorption analysis Small angle X-ray scattering 6 Wood Downdraft 45 120 ~650   X-ray power difgraction Thermogravimetric analysis chips 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 SEM XRD Q: quartz (SiO 2 ), P: portlandite (Ca(OH) 2 ), C: calcite (CaCO 3 ), L: lime (CaO)

Elemental analysis (% wt dry ) Surface area C H N S O Ash pore pore Sampl S BET %wt d %wt d %wt d %wt d %wt d %wt d size volume e m 2 / nm cm 3 /g ry ry ry ry ry ry g 81.1 14.6 CHAR1 0.23 0.28 0.35 3.74 CHAR 3 2 603 3.88 0.30 1 91.3 CHAR2 0.72 0.26 0.57 3.43 4.20 CHAR 9 297 4.50 0.26 2 81.1 16.0 CHAR3 0.25 0.61 0.27 1.89 CHAR 7 8 403 4.70 0.50 3 48.1 49.5 CHAR4 0.49 0.23 0.32 1.64 CHAR 2 2 183 4.90 0.25 4 80.6 15.8  Highest surface area CHAR5 0.55 0.22 0.20 2.79 CHAR 1 ADSORPTION 4 0  427 4.40 0.39 Low amount of ash 5 68.6 27.8 CHAR6 0.33 0.83 0.32 2.05 CHAR  High surface area 3 4 352 4.54 0.24 CATAL Y 2 6  Lowest amount of ash SIS

Outline Char collection CO 2 and characterization adsorption Other H 2 S applications adsorption

Materials and methods Adsorptiv CO 2  T ads = 50 - 75 - 100 °C e:  CO 2 :N 2 = 1:1 - 1:4 Adsorben 5 pure chars  KOH - t: ZnCl 2 2 activated  N 2 chars 2 AC  600 °C  1 hour Thermo-gravimetric tests run in a Jupiter STA449-F3 (Netzsch)

SEM images Results 1 2 3 Adsorption curves 4 5 AC 1 1_KO AC 1_Zn 2 H Cl 2 V. Benedetti et al., CO 2 adsorption study on pure and chemically activated chars derived from commercial biomass gasifjers, J. CO 2 util., 33 (2019) 46-54.

Results Sample Uptake, N 2 uptake, Efgect of T and gas % % composition Uptake, % CHAR1 3.49 0.20 CHAR1 CHAR2 3.04 0.14 Pure char CHAR3 2.09 0.08 4,0 3,49 CHAR4 1.69 0.65 3,5 CHAR5 2.75 0.17 1:1 1:4 3,0 AC1 3.01 0.10 2,48 AC2 2.13 0.07 2,5 CHAR1_K 1,86 1,84 2,0 3.73 1,57 OH 0.35 1,5 CHAR1_Z C A 3.03 1,0 0,74 Activated nCl2 0.13 0,5 char 0,0 50 75 100 T emperature, °C Literatu 2.50 - re 10.70

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

Results - physisorption A m o unt adso rbe d, cm 3/g Uptake, % 4 3 CHAR1 500 CHAR4 AC1 AC2 2 400 CHAR1_KOH CHAR1_ZnCl2 300 1 200 0 100 200 300 400 500 600 700 800 900 1000 1100 100 SBET, m2/g 0 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 Relative pressure, p/p0

Results Adsorption/desorption cycles to test loss of char CHAR1_KOH adsorption capacity U p ta k e , % 103 101 5 TG, % 4 99 3 97 2 1 95 0 10 110 210 310 410 510 610 710 810 910 1010 1110 1 2 3 4 5 6 7 8 9 10 Adsorption cycle time, min  High selectivity  High adsorption capacity Efgective CO 2 adsorbent  Good adsorption/desorption kinetics  Stable adsorption capacity after repeated cycles

Outline Char collection CO 2 and characterization adsorption Other H 2 S applications adsorption

Meterials and methods 1 - Adsorption capacity Adsorptiv H 2 S e: Adsorben 5 pure chars  Fixed bed reactor - quartz t:  Char bed height: 2.5 cm (150 - 2 AC 200 mg)  H 2 S + N 2 : 100 NmL/min  H 2 S: 250 ppm  T amb  Micro-GC for gas analysis at the outlet

Meterials and methods 2 - Efgect of inlet Adsorptiv H 2 S concentration e: Best Adsorben  Fixed bed reactor - quartz performing t:  Char bed height: 2.5 cm (150 - char 200 mg)  H 2 S + N 2 : 100 NmL/min  H 2 S: 250 -550 -1000 ppm  T amb  Micro-GC for gas analysis at the outlet

H 2 S a d s o r p t i o n c a p a c i t y [ m g / g ] Results Efgect of H2S adsorption capacity [mg/g] surface area 8 6,88 7 6 5,41 5,38 5 4 8 2,77 2,61 3 2,35 7 6 1,61 2 5 4 1 3 0 2 char-A char-B char-Cchar-D char-E AC-1 AC-2 1 0 0 250 500 750 1000 1250 1500 Char surface area [m²/g] Literature 1.71 - 65 mg/g AC 0.04 - 0.22 mg/g char from F . Marchelli et al., Experimental study on H 2 S adsorption on gasifjcation char under difgerent operative conditions, Biomass pyrolysis Bioenergy 126 (2019) 106 - 116.

H 2 S a d s o r p t i o n c a p a c i t y [ m g / g ] Results Efgect of Metal content ash 8 7 6 5 4 3 2 1 0 0 10 20 30 40 50 60 Ash content [%]

Results Dimensionless oxygen and metal mass Efgects of: 3,5 8 fraction, and S BET H2S adsorbed amount (mg g-1) 6,88 7 3  Oxygen content 6 5,41 5,38 2,5  Metals mass fraction 5 2  4 Surface area 1,5 2,77 2,61 3 2,35 1 1,61 2 0,5 1 0 0 char-A char-B char-C char-D char-E AC-1 AC-2 Oxygen mass fraction T otal metal mass fraction SBET H₂S adsorbed amount

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 ) Results - Efgect of concentration Inlet H 2 S volume adsorption fraction of Capacity, H 2 S, mg g −1 Breakthrough curves ppm 1000 1000 800 250 6.88 ± 0.37 ppm 600 500 7.87 ± 0.70 400 1000 6.98 ± 0.24 200 0 10 20 30 40 50 60 70 80 90 100 0 Time [min] Low concentrations slow down the process, but do not afgect the adsorption capacity

Outline Char collection CO 2 and characterization adsorption Other H 2 S applications adsorption

Char as catalyst support for Fischer- Tropsch synthesis CO conv., % Char, 10% Co 8 Char, 10% Fe 26 Products distribution Literatur e 15 - 80 V. Benedetti et al., Investigating the feasibility of valorizing residual char from biomass gasifjcation as catalyst support in Fischer- T ropsch synthesis, under review.

Char as catalyst support for Dry Reforming of Methane (DRM) V. Benedetti et al., Valorization of char from biomass gasifjcation as catalyst support in dry reforming of methane, Front. Chem, 7 (2018) 119.

Tar removal by thermal and catalytic cracking Evaluation of tar removal effjciency and analysis of converted products (both condensables and gaseous) Changing operating conditions  Efgect of temperature 800-1000 °C  Efgect of space velocity  Efgect of tar concentration Second stage First stage Other gas Model tar mixtures/real tar compounds: from lab-scale - T oluene gasifjer - Naphthalene - Phenol

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/