Biohydrogen Production from Bio-oil using Steam Reforming, Autothermal Reforming and Water-gas Shift Reactions Songpon Samanpiboonphol Apinya Duangchan Department of Chemical Engineering, Kasetsart University, Thailand.
Outline • Introduction • Objectives • Working scopes • Experimental • Results and discussion • Conclusions
Introduction NREL: 2010 Renewable energy data book.
Renewable energy • Bio-diesel • Bio-ethanol • Bio-oil • Biohydrogen
Pyrolysis Bio-oil organic phase Biomass Thermo chemical decomposition Bio-oil aqueous phase
Hydrogen production Bio-oil aqueous phase Steam reforming reaction CnHm + n H2O ↔ (n + m/2) H2 + n CO Water gas shift reaction CnHm + (m/2) H2O ↔ nCO2 + mH2 Steam reforming Water gas shift Autothermal reforming Biohydrogen Autothermal reforming (Thomaset al., 2000) CnHmOo + ξ(O2+3.76N2) + (2n-2ξ-o)H2O ↔ nCO2 + (2n-2ξ-o+0.5m)H2 + 3.76 ξN2
Objective • To produce hydrogen from bio-oil aqueous phase • via water gas shift, • autothermal reforming and • steam reforming reactions, • by using Cu-Ni-Sn/-Al2O3 catalyst.
Working scopes • Bio-oil was produced from corn cob • Steam to carbon molar ratio was 10:1 • Air flow rate to reactor was 200 cm3/min • Operating temperature limit was 850°C
Experimental • Raw material • Corn cob • Decomposition of corn cob was analysed by thermogravimetric analyzer (TGA) • Composition of corn cob was analyzed by elemental analyzer (EA)
Corn Cob Dried Grinded 0.5-1.0 cm.
Experimental • Pyrolysis • Continuous screw pyrolysis reactor • Reaction temperature of 400 °C • Nitrogen flow rate of 83 cm3/min
Catalyst • Catalyst preparation • Supporter commercial grade nano -Al2O3 was purchased from Dong Yang (HK) group limited. • Ni and Cu metals were added into -Al2O3 by wet impregnation method. • Sn metal was added into Cu-Ni/-Al2O3 catalyst by wet impregnation method.
Catalyst preparation H2O 2Cu 1Ni Solution of Cu-Ni Drying @100 °C over night Wetness impregnation 2Cu-Ni/17 -Al2O3 2Cu-Ni/17 -Al2O3 Stirring 30 min. 17-Al2O3 Calcined @ 500 °C,4hr Cu: Cu(NO3)2 · 3H2O Ni : Ni(NO3)2 · 6H2O
Catalyst preparation H2O 0.25Sn (mol/mol) Solution of Sn Drying @100 °C over night Wetness impregnation 2Cu-Ni-0.25Sn/ 17 -Al2O3 2Cu-Ni-0.25Sn/ 17 -Al2O3 2Cu-Ni/17 -Al2O3 Stirring 30 min. Calcined @ 350 °C,1hr Cu: Cu(NO3)2 · 3H2O Ni : Ni(NO3)2 · 6H2O Sn : SnCl2· 2H2O
Biohydrogen • Biohydrogen production • Ethanol model compoundreforming • Bio-oil aqueous phase reforming • Biohydrogen analysis • Gas chromatograph • Shimadzu GC 2014 was used for analyzing the composition of gas products.
Ethanol model compound reforming H2O ET-OH Non-catalytic -Al2O3 Cu-Ni/-Al2O3 Cu-Ni-Sn/-Al2O3 10:1by mol 100-120 °C Syringe pump Evaporator Horizontal tube reactor 750 °C Gas chromatograph Condenser
Bio-oil aqueous phase reforming H2O Bio-oil aqueous phase Cu-Ni-Sn/-Al2O3 7.5-10.5:1 100-120 °C Syringe pump Evaporator Horizontal tube reactor 185-850 °C Gas chromatograph Condenser
Results and Discussion • Compositon of corn cob • Decomposition of corn cob
Thermogravimetric Analysis (TGA) 25-100 °C 180-350 °C 650-800 °C 10% moisture 17% Residue • Demoisturize, at temperature about 25-100°C • Decomposition of corn cob, about 180-350°C • Corn cob was 10% of moisture and17% of residue
Results and Discussion • Pyrolysis • The composition of bio-oil organic phase and aqueous phase were analyzed by elemental analyzer (EA)
Results and Discussion • Catalyst • Cu-Ni-Sn /-Al2O3Catalyst • X-Ray Fluorescent (XRF) Ac - Actual Cal - Calculated
Results and Discussion • Biohydrogen production • Hydrogen yield calculation • Aqueous ethanol refoming • Bio-oil aqueous phase reforming
Hydrogen Yield Calculation (a) Moles of carbon in feed = 2 × moleHAc While, n, m and k are stoichiometric of C, H and O respectively. For this experiment n=1, m=1.6 and k=0.79 (CH1.6O0.79N0.05 ) So, (2n+(m/2)-k) = 2.01
(b) conc.HAc = concentration of bio-oil = 0.127 gHAc/mL Flow rate = flow rate of bio-oil = 27 mL/h Time = time of taking sample = 1 s Molecular weight of HAc = molecular weight of bio-oil = 26.3 g/mol Substitute all parameter in equation (b)
From the result at operating temperature of 230°C, S/C molar ratio of 10 : 1, the hydrogen produced was 1.23x10-4 mol Substitute all parameters in equation (a)
Aqueous ethanol reforming with steam to carbon molar ratio of 10:1 and operating temperature of 750ºC C2H5OH = 2C + H2O + 2H2 (1) Cracking to C, H2O, H2 C2H5OH+ ξ(O2+3.76N2) + ξH2O = 2CO2 + (12ξ-3)H2 + 3.76ξN2 (2) Autothermal reforming reaction C2H5OH + H2O = 2CO + 4H2 (3)Steam reforming reaction C2H5OH + 3H2O = 2CO2 + 6H2 (4)Water gas shift reaction C2H5OH = C + CO + 3H2 (5) Cracking to C, CO and H2 nCO + (2n+1)H2 = CnH2n+2 + nH2O (6) Fischer Tropsch reaction
Bio-oil aqueous phase reforming using Cu-Ni-Sn/-Al2O3 with steam to carbon molar ratio of 7.5-10.5:1 and operating temperature of 185-850ºC The optimum conditions of the process by using design of experiment in Minitab program. The highest hydrogen yield was at S:C of 10:1 and 230C.
Bio-oil aqueous phase reforming with steam to carbon molar ratio of 7.5-10.5:1 and operating temperature of 185-850ºC The S/C ratio affected the hydrogen yield significantly more than the operating temperature.
Conclusions • Biohydrogen production • Cu-Ni-Sn/-Al2O3 was the best catalyst in this experiment. • Yield of H2 at 230°C and S/C of 10 : 1 was 88.54%, the best condition. • The yield of H2 production from ethanol model compound was consisted the bio-oil aqueous phase. • The steam to carbon molar ratio affected the hydrogen yield significantly more than the operating temperature.
Wang et. al. (2007) • - Studied hydrogen production from bio-oil by steam reforming reaction. • - Using C12A7-O- catalyst. • - Using fixed-bed continuous flow reactor. • - Operating temperature of 750 °C and S/C molar ratio of 9:1 yield of hydrogen 82%
Davda et. al.(2005) • - Review of catalyst for produce hydrogen and alkane by aqueous phase reforming. • - Cu exhibits the highest water-gas shift rate. • - However, Cu metal are not effective for steam reforming. • - Ni promoting high rates of C–C bond cleavage.
Xiaolei et al. (2010) • Studied the steam reforming reaction of dimethyl ether • Using 2Cu-1Ni/17γ-Al2O3 catalyst. • - Ni metal improved the dispersion of Cu • - Increased the interaction between Cu and γ-Al2O3 • - Inhibited the sintering of Cu.
Shabaker et al. (2004) • Studied bio-oil aqueous phase steam reforming • Using 4Ni-Sn/68γ-Al2O3 catalyst • The addition of Sn to Ni significantly decreased the rate of methane formation from C–O bond cleavage • While promoting high rates of C–C bond cleavage was required for hydrogen formation.
Wang et. al. (2009) • Studied steam reforming of dimethyl ether. • Using Cu-Ni/γ-Al2O3 catalyst. • - Ni metal improved the dispersion of Cu. • - Increased the interaction between Cu and γ-Al2O3. • - Inhibited the sintering of Cu. • γ-Al2O3 was decreased the rate of methane formation.
Scanning electron microscopy (SEM) Cu-Ni-Sn/-Al2O3 x2500 -Al2O3 x2500
Al O Cu Ni Sn Gamma Alumina structure
Ethanol reforming using Cu-Ni-Sn/-Al2O3 , S/C molar ratio 10:1 Bio-oil aqueous phase reforming using Cu-Ni-Sn/-Al2O3