Optimization of catalyst pellet structures and operation conditions for CO methanation

doi:10.1016/j.cjche.2021.02.030

摘要/Abstract

摘要： A fundamental understanding of the effects of catalyst pellet structures and operation conditions on catalytic performance is crucial for the reactions limited by diffusion mass transfer. In this work, a numerical investigation has been carried out to understand the effect of catalyst pellet shapes (sphere, cylinder, trilobe and tetralobe) on the reaction-diffusion behaviors of CO methanation. The results reveal that the poly-lobe pellets with larger external specific surface area have shorter diffusion path, and thus result in higher effectiveness factors and CO conversion rates in comparison with the spherical and cylindrical pellets. The effects of operating conditions and pore structures on the trilobular catalyst pellet with high performance are further probed. Though lower temperature can contribute to larger effectiveness factors of pellets, it also brings about lower reaction rates, and pressure has little impact on the effectiveness factors of the pellets. The increase in porosity can reduce the pellet internal diffusion limitations effectively and there exists an optimal porosity for the methanation reaction. Finally, the height of the trilobular pellet is optimized under the given geometric volume, and the results demonstrate that the higher the trilobular catalyst, the better the reaction performance within the allowable mechanical strength range.

关键词: CO methanation, Numerical simulation, Catalyst pellet, Shape effects, Reaction-diffusion behavior

Abstract: A fundamental understanding of the effects of catalyst pellet structures and operation conditions on catalytic performance is crucial for the reactions limited by diffusion mass transfer. In this work, a numerical investigation has been carried out to understand the effect of catalyst pellet shapes (sphere, cylinder, trilobe and tetralobe) on the reaction-diffusion behaviors of CO methanation. The results reveal that the poly-lobe pellets with larger external specific surface area have shorter diffusion path, and thus result in higher effectiveness factors and CO conversion rates in comparison with the spherical and cylindrical pellets. The effects of operating conditions and pore structures on the trilobular catalyst pellet with high performance are further probed. Though lower temperature can contribute to larger effectiveness factors of pellets, it also brings about lower reaction rates, and pressure has little impact on the effectiveness factors of the pellets. The increase in porosity can reduce the pellet internal diffusion limitations effectively and there exists an optimal porosity for the methanation reaction. Finally, the height of the trilobular pellet is optimized under the given geometric volume, and the results demonstrate that the higher the trilobular catalyst, the better the reaction performance within the allowable mechanical strength range.

Key words: CO methanation, Numerical simulation, Catalyst pellet, Shape effects, Reaction-diffusion behavior

Yiquan Zhao, Yao Shi, Guanghua Ye, Jing Zhang, Xuezhi Duan, Gang Qian, Xinggui Zhou. Optimization of catalyst pellet structures and operation conditions for CO methanation[J]. 中国化学工程学报, 2021, 40(12): 106-113.

参考文献

[1] S. Gupta, Natural gas - extraction to end use[M]. InTech, Rijeka, 2012
[2] J. Kopyscinski, T.J. Schildhauer, S.M.A. Biollaz, Production of synthetic natural gas (SNG) from coal and dry biomass - A technology review from 1950 to 2009, Fuel 89 (8) (2010) 1763–1783
[3] S. Rönsch, J. Schneider, S. Matthischke, M. Schlüter, M. Götz, J. Lefebvre, P. Prabhakaran, S. Bajohr, Review on methanation-From fundamentals to current projects, Fuel 166 (2016) 276–296
[4] J.J. Gao, Y.L. Wang, Y. Ping, D.C. Hu, G.W. Xu, F.N. Gu, F.B. Su, A thermodynamic analysis of methanation reactions of carbon oxides for the production of synthetic natural gas, RSC Adv. 2 (6) (2012) 2358
[5] N.S. Govender, F.G. Botes, M.H.J.M. de Croon, J.C. Schouten, Mechanistic pathway for methane formation over an iron-based catalyst, J. Catal. 260 (2) (2008) 254–261
[6] Z.F. Qin, J. Ren, M.Q. Miao, Z. Li, J.Y. Lin, K.C. Xie, The catalytic methanation of coke oven gas over Ni-Ce/Al₂O₃ catalysts prepared by microwave heating: Effect of amorphous NiO formation, Appl. Catal. B: Environ. 164 (2015) 18–30
[7] J.J. Gao, C.M. Jia, J. Li, F.N. Gu, G.W. Xu, Z.Y. Zhong, F.B. Su, Nickel catalysts supported on Barium hexaaluminate for enhanced CO methanation, Ind. Eng. Chem. Res. 51 (31) (2012) 10345–10353
[8] H.W. Zhu, R. Razzaq, L. Jiang, C.S. Li, Low-temperature methanation of CO in coke oven gas using single nanosized Co₃O₄ catalysts, Catal. Commun. 23 (2012) 43–47
[9] K.O. Xavier, R. Sreekala, K.K.A. Rashid, K.K.M. Yusuff, B. Sen, Doping effects of cerium oxide on Ni/Al₂O₃ catalysts for methanation, Catal. Today 49 (1–3) (1999) 17–21
[10] S.H. Kang, J.H. Ryu, J.H. Kim, S.J. Seo, Y.D. Yoo, P.S. Sai Prasad, H.J. Lim, C.D. Byun, Co-methanation of CO and CO₂ on the Ni_x-Fe_1-x/Al₂O₃ catalysts; effect of Fe contents, Korean J. Chem. Eng. 28 (12) (2011) 2282–2286
[11] A.L. Kustov, A.M. Frey, K.E. Larsen, T. Johannessen, J.K. Nørskov, C.H. Christensen, CO methanation over supported bimetallic Ni-Fe catalysts: From computational studies towards catalyst optimization, Appl. Catal. A: Gen. 320 (2007) 98–104
[12] S. Takenaka, T. Shimizu, K. Otsuka, Complete removal of carbon monoxide in hydrogen-rich gas stream through methanation over supported metal catalysts, Int. J. Hydrog. Energy 29 (10) (2004) 1065–1073
[13] D.C. Hu, J.J. Gao, Y. Ping, L.H. Jia, P. Gunawan, Z.Y. Zhong, G.W. Xu, F.N. Gu, F.B. Su, Enhanced investigation of CO methanation over Ni/Al₂O₃ catalysts for synthetic natural gas production, Ind. Eng. Chem. Res. 51 (13) (2012) 4875–4886
[14] K. Urasaki, Y.T. Tanpo, Y. Nagashima, R. Kikuchi, S. Satokawa, Effects of preparation conditions of Ni/TiO₂ catalysts for selective CO methanation in the reformate gas, Appl. Catal. A: Gen. 452 (2013) 174–178
[15] Y. Yu, G.Q. Jin, Y.Y. Wang, X.Y. Guo, Synthetic natural gas from CO hydrogenation over silicon carbide supported nickel catalysts, Fuel Process. Technol. 92 (12) (2011) 2293–2298
[16] J.J. Gao, Q. Liu, F.N. Gu, B. Liu, Z.Y. Zhong, F.B. Su, Recent advances in methanation catalysts for the production of synthetic natural gas, RSC Adv. 5 (29) (2015) 22759–22776
[17] M.G. O'Brien, S.D.M. Jacques, M. di Michiel, P. Barnes, B.M. Weckhuysen, A.M. Beale, Active phase evolution in single Ni/Al₂O₃methanation catalyst bodies studied in real time using combined μ-XRD-CT and μ-absorption-CT, Chem. Sci. 3 (2) (2012) 509–523
[18] S.L. Ma, Y.S. Tan, Y.Z. Han, Methanation of syngas over coral reef-like Ni/Al₂O₃ catalysts, J. Nat. Gas Chem. 20 (4) (2011) 435–440
[19] A.M. Zhao, W.Y. Ying, H.T. Zhang, H.F. Ma, D.Y. Fang, Ni-Al₂O₃ catalysts prepared by solution combustion method for syngas methanation, Catal. Commun. 17 (2012) 34–38
[20] F.B. Derekaya, G. Yaşar, The CO methanation over NaY-zeolite supported Ni/Co₃O₄, Ni/ZrO₂, Co₃O₄/ZrO₂ and Ni/Co₃O₄/ZrO₂ catalysts, Catal. Commun. 13 (1) (2011) 73–77
[21] Y.J. Liu, J.J. Gao, Q. Liu, F.N. Gu, X.P. Lu, L.H. Jia, G.W. Xu, Z.Y. Zhong, F.B. Su, Preparation of high-surface-area Ni/α-Al₂O₃ catalysts for improved CO methanation, RSC Adv. 5 (10) (2015) 7539–7546
[22] K.R. Kaza, J. Villadsen, R. Jackson, 3 Intraparticle diffusion effects in the methanation reaction, Chem. Eng. Sci. 35 (1–2) (1980) 17–24
[23] S.S.E.H. Elnashaie, M.E.E. Abashar, Steam reforming and methanation effectiveness factors using the dusty gas model under industrial conditions, Chem. Eng. Process.: Process. Intensif. 32 (3) (1993) 177–189
[24] D. Mears, Tests for transport limitations in experimental catalytic reactors, Ind. Eng. Chem. Process. Des. Dev. 11 (2) (1972) 320
[25] G.M. Karthik, V.V. Buwa, Particle-resolved simulations of methane steam reforming in multilayered packed beds, AIChE J. 64 (11) (2018) 4162–4176
[26] J.S.S. Mohammadzadeh, A. Zamaniyan, Catalyst shape as a design parameter—optimum shape for methane-steam reforming catalyst, Chem. Eng. Res. Des. 80 (4) (2002) 383–391
[27] C. Italiano, J. Llorca, L. Pino, M. Ferraro, V. Antonucci, A. Vita, CO and CO₂ methanation over Ni catalysts supported on CeO₂, Al₂O₃ and Y₂O₃ oxides, Appl. Catal. B: Environ. 264 (2020) 118494
[28] J. Kopyscinski, T.J. Schildhauer, F. Vogel, S.M.A. Biollaz, A. Wokaun, Applying spatially resolved concentration and temperature measurements in a catalytic plate reactor for the kinetic study of CO methanation, J. Catal. 271 (2) (2010) 262–279
[29] K. Khorsand, M.A. Marvast, N. Pooladian, M. Kakavand, Modeling and simulation of methanation catalytic reactor in ammonia unit, Petroleum Coal 49 (1) (2007) 46–53
[30] F. Kapteijn, A.M. Jacob, Laboratory catalytic reactors: Aspects of catalyst testing,Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2008
[31] R. Byron Bird, Transport phenomena, Appl. Mech. Rev. 55(1) (2002) R1–R4.
[32] E.N. Fuller, P.D. Schettler, J.C. Giddings, New method for prediction of binary gas-phase diffusion coefficients, Ind. Eng. Chem. 58 (5) (1966) 18–27
[33] M. Kleiber, R. Joh, D1 calculation methods for thermophysical properties. VDI Heat Atlas, Springer Berlin Heidelberg, Berlin, Heidelberg, 2010, pp. 119–152.
[34] A.M. Zhao, W.Y. Ying, H.T. Zhang, H.F. Ma, D.Y. Fang, Ni/Al₂O₃ catalysts for syngas methanation: Effect of Mn promoter, J. Nat. Gas Chem. 21 (2) (2012) 170–177
[35] C.L. Yaws, Chemical properties handbook, McGraw-Hill, New York, 1999
[36] B.E. Poling, M.J. Prausnitz, J.P. O'connell, The properties of gases and liquids, McGraw-Hill, New York, 2001.
[37] S. Bac, A.K. Avci, Ethylene oxide synthesis in a wall-coated microchannel reactor with integrated cooling, Chem. Eng. J. 377 (2019) 120104
[38] Y. Dong, F.J. Keil, O. Korup, F. Rosowski, R. Horn, Effect of the catalyst pore structure on fixed-bed reactor performance of partial oxidation of n-butane: a simulation study, Chem. Eng. Sci. 142 (2016) 299–309
[39] Y. Shi, C.F. Yang, X.Q. Zhao, Y.Q. Cao, G. Qian, M.K. Lu, G.H. Ye, C. Peng, B.K. Sui, Z. Lv, W.K. Yuan, X.Z. Duan, X.G. Zhou, Engineering the hierarchical pore structures and geometries of hydrodemetallization catalyst pellets, Ind. Eng. Chem. Res. 58 (23) (2019) 9829–9837
[40] J. Kopyscinski, Production of synthetic natural gas in a fluidized bed reactor,Ph. D. Thesis, ETH Zurich,Switzerland, 2010
[41] H. Er-Rbib, C. Bouallou, Modeling and simulation of CO methanation process for renewable electricity storage, Energy 75 (2014) 81–88
[42] X.Q. Zhao, C.F. Yang, M.K. Lu, Y. Shi, G. Qian, X.G. Zhou, X.Z. Duan, Coupling non-isothermal trickle-bed reactor with catalyst pellet models to understand the reaction and diffusion in gas oil hydrodesulfurization, Chin. J. Chem. Eng. 28 (4) (2020) 1095–1106
[43] Y. Shi, G.H. Ye, C.F. Yang, Y.Q. Tang, C. Peng, G. Qian, W.K. Yuan, X.Z. Duan, X.G. Zhou, Pore engineering of hierarchically structured hydrodemetallization catalyst pellets in a fixed bed reactor, Chem. Eng. Sci. 202 (2019) 336–346
[44] A.P. Kagyrmanova, I.A. Zolotarskii, E.I. Smirnov, N.V. Vernikovskaya, Optimum dimensions of shaped steam reforming catalysts, Chem. Eng. J. 134 (1–3) (2007) 228–234
[45] F.J. Keil, C. Rieckmann, Optimization of three-dimensional catalyst pore structures, Chem. Eng. Sci. 49 (24) (1994) 4811–4822