BIOGAS REFORMING PROCESSES IMPROVEMENTS THROUGH PROCESS INTENSIFICATION THE USE OF MICRO STRUCTURED REACTORS FOR SYNGAS AND HYDROGEN PRODUCTION

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1 BIOGAS REFORMING PROCESSES IMPROVEMENTS THROUGH PROCESS INTENSIFICATION THE USE OF MICRO STRUCTURED REACTORS FOR SYNGAS AND HYDROGEN PRODUCTION U. Izquierdo *,1, V.L. Barrio 1, N. Lago 1, J. Requies 1, J.F. Cambra 1, M.B. Güemez 1, P.L. Arias 1, J.R. Arraibi 2, A.M. Gutiérrez 2 1 Dept. of Chemical and Environmental Engineering, School of Engineering, Bilbao, Spain 2 Naturgas Energía Grupo S.A., Bilbao, Spain

2 OVERVIEW 1. INTRODUCTION 2. OBJECTIVES 3. EXPERIMENTAL METHODOLOGY 4. RESULTS 5. MAIN CONCLUSIONS 6. FUTURE PROSPECTS

3 1. INTRODUCTION Biogas - Renewable source Most harmful greenhouse gases (GHG) - Free CO 2 fuel - Composition: CH 4 : 55-7 CO 2 : H 2 <1 H 2 S <3 NH 3 traces Hydrogen - Clean energy vector - Clean fuel - Main uses: Fuel cells Heavy oil upgrading Desulfurization and upgrading of conventional petroleum Reforming reactions - Dry reforming (DR) CH 4 + CO 2 2 CO + 2 H 2 ΔH = +247 kj/mol - Biogas Oxidative Reforming (BOR) CH 4 + ½ O 2 CO + 2 H 2 ΔH = - 36 kj/mol - Biogas Steam Reforming (BSR) CH 4 + H 2 O CO + 3 H 2 ΔH = + 26 kj/mol - Water gas-shift (WGS) CO + H 2 O CO 2 + H 2 ΔH = - 41 kj/mol

4 2. OBJECTIVES HYDROGEN AND SYNGAS PRODUCTION FROM BIOGAS REFORMING PROCESSES - Development of an active and selective new catalytic systems Ni/MgO Ni/Ce-Al 2 Ni/Zr-Al 2 Ni/Ce-Zr-Al 2 Rh-Ni/Ce-Al 2 Commercial - Comparison between fixed bed and microreactor reaction systems - Decentralized hydrogen production through process intensification

5 3. EXPERIMENTAL METHODOLOGY 3.1. Catalyst preparation Incipient wetness impregnation. Reactors preparation Fixed bed reactor Microreactor - Internal diameter: 6.3 mm - Channel width of 5 μm - Length: 32cm - Channel depth of 25 μm - Stainless steel 316-L - Design focused on Internal and external mass-transfer resistances. - Improvements - Highest surface area/volume relationship - Smaller and more compact systems - Heat transfer optimization - Excellent temperature control - Highest selectivity for the desired products - Cheaper than other equivalent alternatives

6 3. EXPERIMENTAL METHODOLOGY 3.3. Activity measurements Bench-scale Microactivity plant (PID Eng&Tech) Operation conditions: T=173K and P=1bar Model biogas composition: CH 4 :CO 2 = 1.5:1. Biogas oxidative reforming (Biogas OR) O 2 /CH 4 =.125,.25 and.5 Biogas steam reforming (Biogas SR) S/C=1., 2. and 3. Tri reforming (TR) O 2 /CH 4 =.25 and.5 S/C=1., 2. and 3. Measured parameters: Methane conversion: X CH 4 () = (V in CH4 - V out CH4 ) / V in CH4 1 Carbon dioxide conversion: X CO 2 () = (V in CO2 - V out CO2 ) / V in CO2 1 Hydrogen yield: H 2 yield () = V out H2 / (2 V in CH4 + V in H2O ) 1 (H 2 /CO) out molar ratio: (H 2 /CO) out = (V H2 / V CO ) out Where: V i in : volumetric flow-rate of reactant i (NmL/min). V i out : volumetric flow-rate of product i (NmL/min).

7 3. EXPERIMENTAL METHODOLOGY 3.4. Catalyst characterization - Chemical composition of calcined catalysts. ICP-AES instrument. - Textural properties of the calcined and degassed catalysts. N 2 adsorptiondesorption isotherms: BET surface area and pore volume and diameter. - Nickel dispersion, metal surface area and Ni crystallite size. H 2 -pulse chemisorption. - Temperature programmed reduction profiles, TPR, for fresh and reduced catalysts. - SEM micrographs of fresh reduced catalysts and tested catalysts: Surface composition (EDX) and morphology (Secondary electron detectors). - XRD patterns for particle crystallite size. - XPS technique was used to evaluate the surface characteristics.

8 4.1. RESULTS: Fresh catalysts characterization Fresh catalysts. Chemical composition (ICP) and textural properties Catalyst Elemental composition (wt) Surface area Pore volume Pore size (m 2 /g) (cm 3 /g) (Å) Commercial 1 (Ni).4 (Ca) Ni/MgO 17.2 (Ni) Ni/6Ce-Al (Ni) 3.3 (Ce) Ni/8Zr-Al (Ni) 5.5 (Zr) Ni/3Ce-4Zr-Al 2 (Ni) 2.7 (Ce) 3.6 (Zr) Ni-1Rh/6Ce-Al 2 1. (Ni) 3.6 (Ce).9 (Rh) Ce-Al 2 Support Zr-Al 2 Support Ce-Zr-Al 2 Support H 2 chemisorption results for reduced catalysts Catalyst Metal Surface Dispersion Ni Crystallite size Ni crystallite size area (m 2 /g) () (nm) (nm) (XRD) 13Ni/6Ce-Al Ni/3Ce-4Zr-Al Ni-1Rh/6Ce-Al

9 4.1. RESULTS: Fresh catalysts characterization Calcined catalyst SEM micrographs Commercial Ni/MgO Ni/Ce-Al 2 Ni/Zr-Al 2 Ni/Ce-Zr-Al 2 Rh-Ni/Ce-Al 2

10 4.1. RESULTS: Fresh catalysts characterization TPR profiles of fresh calcined catalysts and supports 173K Rh-Ni/Ce-Al 2 Ni/Ce-Zr-Al 2 H 2 consumption (a.u.) Ni/Zr-Al 2 Ni/Ce-Al 2 Ni/MgO Commercial Ce-Zr support Zr support Ce support H 2 consumption (a. u.) T (K) T (K)

11 4.2. ACTIVITY RESULTS: BSR process in a FBR 1 S/C= S/C=2. S/C= Biogas SR activity results at different S/C ratios for Ni/Ce-Zr-Al 2 catalyst 4, 3,2 2,4 1,6,8, 2.8 S/C=1. S/C=2. S/C=

12 4.2. ACTIVITY RESULTS: BOR process in a FBR 1 O 2 /CH 4 = Biogas OR at O 2 /CH 4 =.25 O 2 /CH 4 = Biogas OR activity results at different O 2 /CH ratios for Rh-Ni/Ce-Al 2 catalyst O2/CH4=.125 O2/CH4=.25 O2/CH4=.5 4, 3,2 2,4 1,6,8, 2.8.

13 4.2. ACTIVITY RESULTS: TR process in a FBR 1 TR at O 2 /CH 4 =.5 and S/C= TR at O 2 /CH 4 =.5 and S/C=2. 1 Katalco XCH4 Ni/MgO Ni/Ce-Al2O3 XCO2 Ni/Zr-Al2O3 Ni/Ce-Zr-Al2O3 H2 yield Rh-Ni/Ce-Al2O3 H2out/COout Equilibrium TR at O 2 /CH 4 =.5 and S/C= Biogas TR activity results at O 2 /CH 4 =.5 and different S/C ratios for Rh-Ni/CeAl.8 2 catalyst S/C=1. S/C=2 S/C=3 4, 3,2 2,4 1,6,8, -,8-1,6 molar ratio

14 4.2. ACTIVITY RESULTS: TR and DR processes 1 TR at O 2 /CH 4 =.25 and S/C= TR at O 2 /CH 4 =.25 and S/C=2. Comparison between DR and TR at O 2 /CH 4 =.25 processes for Rh-Ni/Ce-Al 2 catalyst , 3, ,4 1,6,8 molar ratio TR at O 2 /CH 4 =.25 and S/C= XCH4 XCO2 H2 yield H2out/COout.8 DR S/C=1 S/C=2 S/C=3, -,8

15 4.2. ACTIVITY RESULTS: Summary for FBR 1 2 Biogas SR activity results at different S/C ratios for Ni/Ce-Zr-Al 2 catalyst 99,5 67,7, 1,6 S/C=1. S/C=2. S/C=3. 4, 3,2 2,4 1,6,8, 1 2 Biogas OR activity results at different O 2 /CH 4 ratios for Rh-Ni/Ce-Al 2 catalyst 95,7 94,6 9,2 1,2 O2/CH4=.125 O2/CH4=.25 O2/CH4=.5 4, 3,2 2,4 1,6,8, ,2 Biogas TR activity results at O 2 /CH 4 =.5 and different S/C ratios for Rh-Ni/Ce-Al 2 catalyst 66,8 1,9 5,8 S/C=1 S/C=2 S/C=3 4, 3,2 2,4 1,6,8, 1 2 -,8-1,6-2 Comparison between DR and TR at O 2 /CH 4 =.25 processes for Rh-Ni/Ce-Al 2 catalyst 99,1 94,35 75,3 39,1 1,7 DR S/C=1 S/C=2 S/C=3 4, 3,2 2,4 1,6,8, -,8

16 4.3. RESULTS: Tested catalysts characterization Relationship between XPS, ICP and H 2 chemisorption.24 Fresh catalyst Tested catalyst Metal disperson 1 2 Measured by ICP-AES Fresh catalyst Tested catalyst Metal dispersion 1 2 Measured by ICP-AES.24 Ni/Al or Ni/Mg surface atomic ratios.16.8 Ni/MgO Commercial Ni/Ce-Zr-Al 2 Ni/Zr-Al 2 Ni/Ce-Al 2 Rh-Ni/Ce-Al Metal dispersion degree 1-2 Ni/Al or Ni/Mg surface atomic ratios.16.8 Ni/MgO Commercial Ni/Zr-Al 2 Ni/Ce-Al 2 Rh-Ni/Ce-Al 2 Ni/Ce-Zr-Al Metal dispersion degree Biogas TR hydrogen yield results () for catalysts tested in the FBR Biogas OR hydrogen yield results () for catalysts tested in the FBR

17 RESULTS: Comparison FBR Vs MICRO Biogas OR at O 2 /CH 4 =.25 4, 3,2 2,4 1,6,8 XCH4 () XCO2 () H2 yield () H2out/COout, Ni/Ce-Al 2 CH 4 Turnover Frequency: TOF CH 4 (s -1 ) X CH4 N CH4 in / (w cat wt Met D Met / Pm Met ) TOF & PROD 1-2 (s-1) Ni/Ce-Al2O3 Micro Ni/Ce-Al2O3 FBR Ni/Ce-Zr-Al2O3 Micro Ni/Ce-Zr-Al2O3 FBR Rh-Ni/Ce-Al2O3 Micro Rh-Ni/Ce-Al2O3 FBR Biogas OR at O 2 /CH 4 =.25 CH4 TOF (s-1) H2 PROD (s-1) Ni/Ce-Al2O3 Micro Ni/Ce-Al2O3 FBR Ni/Ce-Zr-Al2O3 Micro Ni/Ce-Zr-Al2O3 FBR Rh-Ni/Ce-Al2O3 Micro Rh-Ni/Ce-Al2O3 FBR H 2 Catalysts Productivity: PROD H 2 (s -1 ) N out H2 / (w cat wt Met D Met / Pm Met ) Where: N i : molar flow of i (methane or hydrogen). w cat : catalyst weight in each reactor system. wt Me : elemental weight given by ICP-AES. D Me : metal dispersion for the catalyst. Pm Me : metal molecular weight. Ni/Ce-Zr-Al 2 Ni-Rh/Ce-Al 2

18 4. RESULTS: Comparison FBR Vs MICRO 1 2 TR at O 2 /CH 4 =.25 and S/C=1. 3, 2,4 1,8 1,2,6 XCH4 () XCO2 () H2 yield () H2out/COout, Ni/Ce-Al 2 CH 4 Turnover Frequency: TOF CH 4 (s -1 ) X CH4 N CH4 in / (w cat wt Met D Met / Pm Met ) (TOF & PROD) 1-2 (s -1 ) 12 1 Ni/Ce-Al2O3 micro Ni/Ce-Al2O3 FBR Ni/Ce-Zr-Al2O3 micro Ni/Ce-Zr-Al2O3 FBR Ni-Rh/Ce-Al2O3 micro Ni-Rh/Ce-Al2O3 FBR 2 TR at O 2 /CH 4 =.25 and S/C=1. TOF CH4 (mol/g s) PROD H2 (mol/g s) Ni/Ce-Al2O3 Micro Ni/Ce-Al2O3 FBR Ni/Ce-Zr-Al2O3 Micro Ni/Ce-Zr-Al2O3 FBR Rh-Ni/Ce-Al2O3 Micro Ni-Rh/Ce-Al2O3 FBR H 2 Catalysts Productivity: PROD H 2 (s -1 ) N out H2 / (w cat wt Met D Met / Pm Met ) Where: N i : molar flow of i (methane or hydrogen). w cat : catalyst weight in each reactor system. wt Me : elemental weight given by ICP-AES. D Me : metal dispersion for the catalyst. Pm Me : metal molecular weight. Ni/Ce-Zr-Al 2 Ni-Rh/Ce-Al 2

19 5. MAIN CONCLUSIONS For all tested catalysts and studied processes, high CH 4 and CO 2 conversions were reached in the fixed bed reactor, in which Ni/Ce-Zr-Al 2 and Rh-Ni/Ce-Al 2 catalysts reached the highest hydrogen production yield. Reforming processes: Biogas OR process: Highest CO 2 conversions and H 2 yield were reached at O 2 /CH 4 =.25. No filamentous carbon deposition was detected in the catalytic surfaces. TR process: The best results for this process were measured at O 2 /CH 4 =.25 and S/C=1.. However, negative CO 2 conversions were measured operating at O 2 /CH 4 =.5. Catalysts: Ni/Ce-Al 2 : High CH 4 and CO 2 conversion values were reached in all tested processes. Ni/Ce-Zr-Al 2 : For this catalyst, the highest CO 2 conversion values were measured. In addition, also high methane conversions were reached. Comparing the processes, it was considered the best catalysts for biogas SR process. Ni-Rh/Ce-Al 2 : Very high CH 4 and CO 2 conversion and the highest hydrogen yields values were reached by this catalyst. It was considered the best catalyst for DR, biogas OR and TR processes. Reaction systems: For microreactors: Ni/Ce-Al 2 catalysts reached the highest hydrogen yield for biogas OR process. Ni/Ce-Zr-Al 2 catalyst reached the highest hydrogen yield for biogas TR process. The catalytic activity measured in microreactors (TOF and PROD) was one order of magnitude higher. THE MICROREACTOR SYSTEM IMPROVES THE STABILITY OF THE PROCESS AND INCREASES THE WHSV, WHICH ARE NECESSARY FOR PROCESS INTENSIFICATION

20 6. FUTURE PROSPECTS THANK YOU FOR - Durability tests YOUR ATTENTION - Test a new catalytic systems: Zeolites - Experiments with another renewable feeds: bioalcohols urko.izquierdo@ehu.es

21 BIOGAS REFORMING PROCESSES IMPROVEMENTS THROUGH PROCESS INTENSIFICATION THE USE OF MICRO STRUCTURED REACTORS FOR SYNGAS AND HYDROGEN PRODUCTION U. Izquierdo *,1, V.L. Barrio 1, N. Lago 1, J. Requies 1, J.F. Cambra 1, M.B. Güemez 1, P.L. Arias 1, J.R. Arraibi 2, A.M. Gutiérrez 2 1 Dept. of Chemical and Environmental Engineering, School of Engineering, Bilbao, Spain 2 Naturgas Energía Grupo S.A., Bilbao, Spain