Dr Panagiotis Kechagiopoulos. Lecturer in Chemical Engineering. School of Engineering

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1 Catalytic reforming of biomass derived oxygenates for sustainable hydrogen production: Experimental investigations, microkinetic modelling and reactor design Dr Panagiotis Kechagiopoulos Lecturer in Chemical Engineering School of Engineering

2014 Present: Lecturer in Chemical Engineering, UoA 2012 2014: Industrial Research Fund Technology developer, UGent 2010 2012: Postdoctoral researcher, UGent

2 2014 Present: Lecturer in Chemical Engineering, UoA : Industrial Research Fund Technology developer, UGent : Postdoctoral researcher, UGent : Diploma in Chemical Engineering, AUTh : Doctor of Chemical Engineering, AUTh : Master in Information Systems, Hellenic Open University

Methodology: Molecule-to-process modelling Intrinsic

Conservation laws Axial Flow Microkinetic network

model Plant wide optimization Industrial reactor design

3 Methodology: Molecule-to-process modelling Intrinsic kinetic laboratory data (Semi-)theoretical calculations Conservation laws Axial Flow Microkinetic network Changing concentration Next volume segment Reactor model Plant wide optimization Industrial reactor design and optimization Coolant Transport phenomena Feed Catalyst Products

4 Introduction Diminishing fossil fuels resources and associated environmental issues have intensified the search for alternative renewable fuels Hydrogen is a clean energy source when derived from renewable sources Catalytic steam reforming to H 2 H 2 Fuel cells Pyrolysis (500 o C, no air) Char Vapours Combustion Condensation Liquids HDO Gases (H 2, CO, CH 4, C 2 H 2, C 2 H 4 ) Bio oil Sugars, phenols, acids, furans, aldehydes, alcohols, ketones Hydrophobic lignin derived fraction + Aqueous fraction

5 Experimental procedures Micro Activity-effy unit Study of chemical reaction kinetics Measurements of catalytic activity

6 Experimental procedures Nickel-based catalysts Sepiolite as catalyst support excellent ability in C-C, C-H, C-O bond cleavage acceptable cost efficient activity in steam reforming reactions at low temperatures hydrated magnesium silicate mineral good mechanical and thermal stability as well as a high surface area (120 m 2 /g) SiO2 as catalyst support relatively inert high surface area ( 155 m 2 /g) Reactants Aqueous fraction of bio-oil model compounds: Ethanol, Acetic acid Lignin derived fraction of bio-oil model compounds or Biomass gasification tars: Phenol, Toluene, Cresol Planned catalysts Pd on SiO 2 and Sepiolite Ni on CeZrLa mixed oxides Rh on CeZrLa mixed oxides

7 Steam Reforming of Ethanol a) CH 3 CH 2 OH CH 3 CHO + H 2 b) CH 3 CH 2 OH CH 4 + CO + H 2 c) CH 3 CHO CH 4 + CO d) CO + H 2 O CO 2 + H 2 e) CH 4 + H 2 O CO + 3H 2 CH 4 + 2H 2 O CO 2 + 4H 2 CH 3 CH 2 OH + 2H 2 O 5H 2 + 2CO (1) CO + H 2 O CO 2 + H 2 (2) CH 3 CH 2 OH + 3H 2 O 6H 2 + 2CO 2, ΔΗ 0 = 207,7 kj/mol

8 ln k Ni/SiO Temperature Effect, Activation energy estimation Total Conversion Temperature ( o C) E E E E E y = x R² = /T (1/K) Ea = kj/mol C Selectivity Eq CO CO Temperature ( o C) C Selectivity C2H4O Eq CH4 CH4 CO2 Eq CO2 Eq C2H4O Temperature ( o C)

9 r (1/s) Ni/SiO Steam to Carbon effect Order of the reaction Partial Pressure of Ethanol varied Total Conversion S/C y = 1.239x R² = Partial Pressure of EtOH (bar) r (1/s) Partial Pressure of Water varied Total Conversion S/C y = x R² = Partial Pressure Water (bar) ESR is nearly first-order (1.24) with respect to ethanol and slightly negative (-0.06) with respect to water

10 Ni/SiO 2 Steam to Carbon effect C Selectivity Partial Pressure of Ethanol varied 6 5 Eq CO2 3 CO2 CO 1 Eq CO S/C CO Eq CO Partial Pressure of Water varied CO2 Eq CO S/C 6 Eq CH4 6 Eq CH4 CH4 C2H4O C2H4O CH4 Eq C2H4O S/C Eq C2H4O S/C

11 Steam to Carbon effect Ni/SiO 2 and Ni/Sepiolite r (1/s) Partial Pressure of Ethanol varied Conversion Ni/Sep Ni/SiO S/C Ni/Sep Ni/SiO Partial Pressure of Ethanol (bar) r (1/s) 3 25% 15% 1 5% Partial Pressure of Water varied Conversion Ni/Sep Ni/SiO S/C 0.10 Ni/SiO Ni/Sep Partial Pressure of Water (bar)

12 Steam to Carbon effect C Selectivity on Ni/SiO 2 and Ni/Sepiolite Partial Pressure of Ethanol varied Partial Pressure of Water varied S/C Ni/SiO 2 C-Sel CO Ni/SiO 2 C-Sel CO 2 Ni/Sep C-Sel CO Ni/SiO 2 C-Sel CO S/C Ni/SiO 2 C-Sel CO Ni/Sep C-Sel CO 2 Ni/Sep C-Sel CO 8 6 Ni/Sep C-Sel CO S/C Ni/SiO 2 C-Sel CH 4 Ni/Sep C-Sel CH S/C S/C 4 6 Ni/SiO 2 C-Sel CH 4 Ni/Sep C-Sel CH S/C

13 Microkinetic modelling C 2 H 5 OH + * C 2 H 5 OH* H 2 O + * H 2 O* H 2 + 2* 2H* CH 4 + 2* CH 3 * + H* CO + * CO* CO 2 + * CO 2 * CH 3 OH + * CH 3 OH* C 2 H 4 O + * C 2 H 4 O* H 2 O* + * OH* + H* C 2 H 5 OH* + * C 2 H 5 O* + H* C 2 H 5 O* + * C 2 H 4 O* + H* CH 3 * + * CH 2 * + H* C 2 H 4 O* + * CHO* + CH 3 * CHO* + * CO* + H* CH 2 * + * CH* + H* C 2 H 4 O* + H* HCHO* + CH 3 * CH 3 * + OH* CH 3 OH* + * C 2 H 4 O* + * CH 3 CO* + H* CH 3 CO* + * CO* + CH 3 * CH 3 CO* + * CH 2 CO* + H* CH 2 CO* + * CO* + CH 2 * CH 2 CO* + * CHCO* + H* CHCO* + * CO* + CH* CO* + OH* COOH* + * COOH* + * CO 2 * + H* HCHO* + OH* HCOOH* + H* HCOOH* + * COOH* + H* OH* + * O* + H* CH* + O* CHO* + * C 2 H 5 OH* + * C 2 H 4 OH* + H* C 2 H 4 OH* + * CH 3 COH* + H* CH 3 COH* + * CH 3 CO* + H*

Microkinetic modelling Pre-exponential factors Entropic consistency ΔSS ee ss,ii RR = AA ff bb ii AA ii Surface species entropy linked to gas phase SS oo ss,jj = SS oo gg,jj oo SS

14 Microkinetic modelling Pre-exponential factors Entropic consistency ΔSS ee ss,ii RR = AA ff bb ii AA ii Surface species entropy linked to gas phase SS oo ss,jj = SS oo gg,jj oo SS tttttttttttttttttttttttttt_3dd,jj Transition state theory for surface reactions AA ii ff = kk ii = kk bbtt h QQ AAAA QQ AA QQ BB Rotational degrees of freedom considered Collision theory for adsorption reactions AA ff ii = kk ii = SS pp LLnn tt 2ππMM jj RRRR Sticking coefficients 1 H H H H rotation around adjoining Carbon C C H O Rotation Axis H Absorbed atom Direction of rotation - Individual atom moments of inertia are calculated with respect to absorbed atom - Atomic moments of inertia are calculated with respect to adjoining atoms - Summation gives total moment of inertia of the specie Catalyst surface

15 Microkinetic modelling Activation energies Enthalpic consistency EE ff ii EE bb ii = ΔHH ss,ii Surface species enthalpy linked to equivalent gas phase HH oo ss,jj = HH oo gg,jj QQ ccccccccccccccccccccccccc,jj EE ii ff through unity bond index-quadratic exponential potential method (UBI-QEP) AA +BB CC +DD EE ff ii = 1 ΔHH 2 ss,ii + QQ CCQQ DD QQ CC +QQ DD ΔHH ss,ii = ΔHH gg,ii + QQ AA + QQ BB QQ CC QQ DD Model parameterised based on adsorption enthalpies of surface species QQ ii QQ ii from literature DFT results or regression CH 3 CH 2 OH* CH 3 * COOH* CH 3 CH 2 O* CH 2 * HCOOH* CH 3 CHO* CH* H 2 O* CH 3 CHOH* CO* OH* CH 3 COH* CO 2 * H* CH 3 CO* CHO* O* CH 2 CO* HCHO* * CHCO* CH 3 OH*

16 Comparison of model predicted to experimental results for Temperature effect Conversion 25% 15% 1 Ethanol Conversion Experimental Model Conversion Water Conversion Experimental Model 5% 1. Molar flow Temperature Temperature CO outlet flow CO 2 outlet flow CH 4 outlet flow 1.5E E E E Temperature Molar flow 8.E-05 6.E-05 4.E-05 2.E-05 0.E Temperature Molar flow 2.E-04 2.E-04 1.E-04 5.E-05 0.E Temperature

17 Comparison of model predicted to experimental results for partial pressure effect r(1/s) Partial Pressure of Ethanol effect y = x y = x Model Experiment Partial Pressure of Ethanol r(1/s) Partial Pressure of Water effect y = x y = x Model Experiment Partial Pressure of water Partial pressure of ethanol and water effect on reaction rate shows an approximately first and zero order for both experimental and modelling results

18 Reactor design: Spouted bed reactors investigation Excellent gas-particle contact Very short residence time of the gas phase Decoupling of gas/solid residence time Efficient heat recirculation Easy to scale-up Flexibility in particle sizes and distributions Modelling assumptions 1D-heterogeneous reactor model Spout and Annulus regions considered Ethylene glycol reforming case study Gas-phase microkinetic model 39 species, 250 radical reactions Heterogeneous catalytic microkinetic model 17 species, 22 surface reactions Gas entrance Fountain Bed surface Spout Annulus region Spout-annulus interface Conical base

19 Ethylene glycol reforming ) 10 T ( o C) T sg T sp T ag T ap Spout concentration (mol/m C H O s CO 2 s CO s H 2 s H O 2 s CH AA s 4 s Reactor Length (m) Temperature profile indicative of highly efficient heating achieved in the bed Annulus region very dense: Equilibrium concentration achieved Spout region very dilute: Activity of catalyst crucial to performance 3 Annulus concentration (mol/m ) Reactor Length (m) Reactor Length (m)

20 Conclusions Kinetic study of ethanol steam reforming over Ni supported on Sepiolite and Silica revealed a striking mechanistic difference Results on Ni/SiO 2 suggest a metal-dominated reaction Decomposition of ethanol on Ni sites appears to be the rate determining step Steam derived intermediates contribute to the (partial) equilibration of the water-gas shift. On Ni/Sepiolite a water activation-limited pathway is observed The occurrence of ethanol activation on the acid sites of the support is possible. Microkinetic modelling results agree well with a metal-dominated reaction mechanism, as observed on Ni/SiO 2. Extensions currently implemented in the model will explicitly account for support effects and elucidate the differences among the two catalysts. Reactor scale simulations reveal the need to further account for the effect of gas-phase reactions and transport phenomena in addition to heterogeneous chemistry to enable the efficient design of such processes.

Acknowledgements Collaborating researchers Marinela Zhurka (PhD student on experimentation) Teejay Afolabi (PhD student on modelling) Prof James Anderson

21 Acknowledgements Collaborating researchers Marinela Zhurka (PhD student on experimentation) Teejay Afolabi (PhD student on modelling) Prof James Anderson (Professor in Chemical Engineering) Prof Chun-Zhu Li (Director of Fuels and Energy Technology Institute, Curtin University, Perth, WA) You for your attention!

Understanding Chemical Reactions through Computer Modeling. Tyler R. Josephson University of Delaware 4/21/16

Understanding Chemical Reactions through Computer Modeling Tyler R. Josephson University of Delaware 4/21/16 A little about me B.S. in Chem E from U of M, 2011 Currently, Ph.D. student at University of