CO 2 Capture and Conversion by Combined Chemical Looping

Transcription

1 CO 2 Capture and Conversion by Combined Chemical Looping Lukas Buelens, A. Dharanipragada, V.V. Galvita, H. Poelman, G.B. Marin Laboratory for Chemical Technology, Ghent University 1

2 Introduction CO 2 capture and conversion WHY? HOW? Reducing CO 2 emissions by valorization of CO 2 Widely studied chemical looping processes CaO s + CO 2 (g) CaCO 3 s 4MO x s + CH 4 (g) 4MO x 1 s + CO 2 g + 2H 2 O g r H 298K = kj mol CO 2 4MO x 1 s + 4CO 2 (g) 4MO x s + 4CO g Catalytic dry-reforming CO 2 (g) + CH 4 (g) 2CO (g) + 2H 2 (g) r H 298K = kj mol CO 2 2

3 Introduction Catalyst-assisted combined chemical looping = Combination of 3 former processes Catalyst-assisted reforming of CH 4 : syngas production Metal oxide reduction: endothermic process CO 2 sorbent carbonation: exothermic process CO 2 (g) + CH 4 (g) 2CO (g) + 2H 2 (g) e.g. biogas MO x s + CO (g) MO x 1 s + CO 2 g MO x s + H 2 (g) MO x 1 s + H 2 O g CaO s + CO 2 (g) CaCO 3 s STEP I Oxidation of methane 3

4 Catalyst-assisted combined chemical looping = Combination of 3 former processes: CO 2 sorbent decarbonation: endothermic process Metal oxide oxidation: exothermic process Introduction Ratio of H 2 :CO from CH 4 reforming in STEP I no influence on CO yield Method for enhanced CO production from CO 2 and CH 4 GLOBAL REACTION 3CO 2 (g) + CH 4 (g) 4CO (g) + 2H 2 O g water-gas shift CaCO 3 s CaO s + CO 2 (g) MO x 1 s + CO 2 g MO x s + CO (g) STEP II Conversion of CO 2 4

5 Outline 1. Introduction 2. Materials and Methods 3. Results Process thermodynamics Experimental proof of concept 4. Conclusions 5. Acknowledgements 5

6 Materials CH 4 -reforming catalyst: 10Ni-MgAl 2 O * 4 (10w% Ni) Oxygen carrier: 50Mg-Fe-Al-O ** (50w% Fe 2 O 3 equivalent) CO 2 sorbent: 90Ca-Al-O (90w% CaO equivalent) Methods EkviCalc Software thermodynamics Materials and Methods * S.A. Theofanidis et al. (2015). ACS Catal., 5 (5): ** N.V.R.A. Dharanipragada et al. (2015). J. Mater. Chem. A, 3: In situ XRD reactor solid phase X-ray source feed Linear detector products Step response reactor gas phase feed products MS Nolang, B. Ekvicalc and Ekvibase; version 4.30; Svensk Energi Data: Balinge, Sweden,

7 Process thermodynamics p=1atm CaO s + CO 2 (g) CaCO 3 s r H 298K = kj mol CO 2 FeO x s + H 2 (g) FeO x 1 s + H 2 O g 2FeO x s + H 2 (g) + CO (g) 2FeO x 1 s + H 2 O g + CO 2 (g) Region of interest FeO x s + CO (g) FeO x 1 s + CO 2 g 7

8 Process thermodynamics In situ XRD: p=1.013bara, T=1023K, F tot =1.8Nml/s (5% H 2 and CO 2 in 90% N 2 ; 100% He ; 100% CO 2 ) p=1atm Slow reduction of Fe 2 O 3 into a mixture of Fe 3 O 4 and FeO when exposed to H 2 :CO 2 (1:1 molar ratio) Fe 3 O 4 FeO in compliance with thermodynamics 8

9 Process thermodynamics: Role of CaO In situ XRD: 50Mg-Fe-Al-O + 90Ca-Al-O (1:2 p=1.013bara, T=1023K, F tot =1.8Nml/s (5% H 2 and 5, 10, 15 or 20% CO 2 in N 2 ; 100% He ; 100% CO 2 ) Fast reduction of Fe 2 O 3 into a mixture of FeO and Fe when exposed to H 2 :CO 2 (1:1 molar ratio) Fast reduction to FeO when exposed to H 2 :CO 2 in molar ratio of 1:2, 1:3 or 1:4 9

10 Process thermodynamics: Role of CaO p=1atm In situ XRD: 50Mg-Fe-Al-O + 90Ca-Al-O (1:2 In situ XRD: p=1.013bara, 50Mg-Fe-Al-O p=1.013bara, F tot =1.8Nml/s T=1023K, (5% F tot =1.8Nml/s H 2 and CO(5% 2 in H90% 2 andn CO 2 ; 100% 2 in 90% He N; 100% 2 ; 100% COHe 2 ) ; 100% CO 2 ) Fe 3 O 4 FeO without CO 2 removal versus Fe 3 O 4 FeO Fe with CO 2 removal 10

11 GLOBAL REACTION 3CO 2 (g) + CH 4 (g) 4CO (g) + 2H 2 O g Proof of concept Step response reactor: 10Ni/MgAl 2 O Mg-Fe-Al-O + 90Ca-Al-O (1:3:6 p=1.3bara, T=1023K, F tot = mol/s (CH 4 :CO 2 in 1:3 molar ratio ; He as sweep gas) 5 repeat experiments STEP I CH 4 :CO 2 (1:3 molar ratio) STEP II He as sweep gas STEP I STEP II Oxidation of T=1023K and CH 4 :CO 2 (1:3 mol) Near to complete oxidation of CH 4, H 2 and CO Removal of CO 2 by formation of CaCO 3 Production of H 2 O * P. Heidebrecht et al. (2009). Chem. Eng. Sci., 64: Conversion of CO T=1023K REACTOR CONFIGURATION * 2.9 ± 0.1 mol CO produced per mol CH 4 fed FeO x not completely reoxidized by CO 2 released from regenerating CaCO 3 Theoretical maximum in this experiment: 3.9 ± 0.1 mol CO produced per mol CH 4 fed 11

12 Catalyst-assisted combined chemical looping: Conclusions Method for enhanced CO production from CO 2 and CH 4 (e.g. starting from biogas + CO 2 ) The achieved CO yield was 2.9 mol CO/mol CH 4 (50% higher than catalytic dry-reforming) while the maximal possible yield was 3.9 mol CO/mol CH 4 (100% higher than catalytic dry-reforming) Super -dry reforming of CH 4 Inherent separation of CO/CO 2 from H 2 O avoiding WGS reaction Each step consists both endothermic and exothermic processes 12

13 Acknowledgements Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT Vlaanderen) Flemish government for long-term structural funding (Methusalem) Interuniversity Attraction Poles (IAP) from BELgian Science Policy Office (Belspo) Fund for Scientific Research Flanders FWO (Project: G004613N) Prof. Christophe Detavernier, Department of Solid State Sciences, Ghent University, Ghent, Belgium. 13

14 Thank you 14