Preliminary Characterization of CaO and Al₂O₃ Catalysts for Biomass-Derived Bio-Oil Production

Abstract:

This study presents the preliminary characterization of commercial calcium oxide (CaO) and aluminum oxide (Al₂O₃) catalysts intended for application in the catalytic upgrading of biomass-derived bio-oil. The catalysts were characterized using Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area analysis, Thermo gravimetric Analysis (TGA), and X-ray Diffraction (XRD). SEM images revealed that both catalysts exhibit irregular, rough-surfaced particles with visible fractures and mesostructured textures conducive to catalytic activity. BET results indicated a specific surface area of 50.301 m²/g for CaO and 129.442 m²/g for Al₂O₃, with corresponding pore diameters of 2.64 nm and 2.647 nm, respectively, confirming their mesoporosity. TGA of CaO showed substantial weight loss associated with moisture, hydroxide, and carbonate decomposition, indicating the need for pre-calcination to restore active oxide phases. In contrast, Al₂O₃ exhibited minor mass loss mainly due to dehydration and dehydroxylation of surface-bound species. XRD analysis confirmed the presence of crystalline γ-Al₂O₃ and highly crystalline CaO with characteristic diffraction planes for their respective phases. These findings demonstrate that both commercial catalysts possess favorable physicochemical properties particularly high surface area, thermal stability, and mesoporous structure that make them promising candidates for vapor-phase upgrading in biomass pyrolysis systems.

• Periodical: Key Engineering Materials (Volume 1045)
• Pages: 53-66
• DOI: https://doi.org/10.4028/p-bOt6CT
• Online since: March 2026
• Authors: Hauwa Abubakar Kaoje*, Adekule A. Adeleke, Adebayo Olosho, Seun Jesuloluwa, Abdullahi Suleiman Bah Gimba, Hauwa Rasheed, Dakut John Yerima
• Keywords: Biomass Pyrolysis, Bio-Oil Upgrading, CaO, Catalyst Characterization, Porosity, Surface Area, γ-Al₂O₃

References

[1] P. R. Bhoi, A. S. Ouedraogo, V. Soloiu, and R. Quirino, "Recent advances on catalysts for improving hydrocarbon compounds in bio-oil of biomass catalytic pyrolysis," Renewable and Sustainable Energy Reviews. 2020.

DOI: 10.1016/j.rser.2019.109676

[2] L. Dai, Y. Wang, Y. Liu, C. He, R. Ruan, Z. Yu, L. Jiang, Z. Zeng, Q. Wu, A review on selective production of value-added chemicals via catalytic pyrolysis of lignocellulosic biomass. Science of the Total Environment. 2020 Dec 20;749:142386.

DOI: 10.1016/j.scitotenv.2020.142386

[3] R. Liu, M.M. Rahman, M. Sarker, M.Chai, C. Li, J. Cai, A review on the catalytic pyrolysis of biomass for the bio-oil production with ZSM-5: Focus on structure. Fuel Processing Technology. 2020 Mar 1;199:106301.

DOI: 10.1016/j.fuproc.2019.106301

[4] T. Kan, V. Strezov, T. Evans, J. He, R. Kumar, and Q. Lu, "Catalytic pyrolysis of lignocellulosic biomass: A review of variations in process factors and system structure," Renewable and Sustainable Energy Reviews. 2020.

DOI: 10.1016/j.rser.2020.110305

[5] R. K. Mishra and K. Mohanty, "Thermal and catalytic pyrolysis of pine sawdust (Pinus ponderosa) and Gulmohar seed (Delonix regia) towards production of fuel and chemicals," Mater. Sci. Energy Technol., vol. 2, no. 2, p.139–149, 2019.

DOI: 10.1016/j.mset.2018.12.004

[6] W. Sun, Y. Yan, Y. Wei, J. Ma, Z. Niu, and G. Hu, "Catalytic Pyrolysis of Biomass: A Review of Zeolite, Carbonaceous, and Metal Oxide Catalysts," Nanomaterials, vol. 15, no. 7, p.1–22, 2025.

DOI: 10.3390/nano15070493

[7] Z. Xue, Z. Zhong, B. Zhang, and C. Xu, "Performance of catalytic fast pyrolysis using a γ-Al2O3 catalyst with compound modification of ZrO2 and CeO2," Catalysts, vol. 9, no. 10, 2019.

DOI: 10.3390/catal9100849

[8] M. Sandelic, S. Peyghami, A. Sangwongwanich, and F. Blaabjerg, "Reliability aspects in microgrid design and planning: Status and power electronics-induced challenges," Renew. Sustain. Energy Rev., vol. 159, no. February, p.112127, 2022.

DOI: 10.1016/j.rser.2022.112127

[9] R. K. Mishra and K. Mohanty, "Pyrolysis of low-value waste sawdust over low-cost catalysts: physicochemical characterization of pyrolytic oil and value-added biochar," Biofuel Res. J., vol. 9, no. 4, p.1736–1749, 2022.

DOI: 10.18331/brj2022.9.4.4

[10] M. N. Nduni, A. M. Osano, and B. Chaka, "Synthesis and characterization of aluminium oxide nanoparticles from waste aluminium foil and potential application in aluminium-ion cell," Clean. Eng. Technol., vol. 3, p.100108, 2021.

DOI: 10.1016/j.clet.2021.100108

[11] B. Flores, M. Guzman, O. Chumpitaz, S. Flores, A. Rodriguez, and J. E. Herrera, "Crystallographic and optical properties of ZnO nanoparticles prepared by two different methods," Appl. Phys. A Mater. Sci. Process., vol. 131, no. 4, 2025.

DOI: 10.1007/s00339-025-08431-z

[12] A. Bin Sulayman and H. de Lasa, "A Kinetic Model for Catalytic N-Butane Oxidative Dehydrogenation under Oxygen-Free Reaction Conditions in a Fluidized CREC Riser Simulator," Catalysts, vol. 14, no. 8, 2024.

DOI: 10.3390/catal14080505

[13] X. Zhang, R. Han, Y. Liu, H. Li, W. Shi, X. Yan, X. Zhao, Y. Li, B. Liu, Porous and graphitic structure optimization of biomass-based carbon materials from 0D to 3D for supercapacitors: A review. Chemical Engineering Journal. 2023 Mar 15;460:141607.

DOI: 10.1016/j.cej.2023.141607

[14] M.F. Zamri, S.H. Hassan, S.K. Tiong, J. Milano, R. Bahru, I.M. Fattah, T.M. Mahlia, Progress and challenges of mesoporous catalysts in upgraded pyrolysis of biomass for biofuel production. Journal of Analytical and Applied Pyrolysis. 2024 Sep 1;182:106651.

DOI: 10.1016/j.jaap.2024.106651

[15] P. Maziarka, N. Kienzl, A. Dieguez-Alonso, V. Fierro, A. Celzard, P.J. Arauzo, N. Hedin, W. Prins, A. Anca-Couce, J.J. Manyà, F. Ronsse, Part 1─ Impact of pyrolysis temperature and wood particle length on vapor cracking and char porous texture in relation to the tailoring of char properties. Energy & Fuels. 2024 May 24;38(11):9751-71.

DOI: 10.1021/acs.energyfuels.4c00937

[16] A. P. S. Dias and M. Ramos, "On the storage stability of CaO biodiesel catalyst. Hydration and carbonation poisoning," J. Environ. Chem. Eng., vol. 9, no. 1, p.104917, Feb. 2021.

DOI: 10.1016/j.jece.2020.104917

[17] C. Sun, Z. Zhou, H. Tian, S. Cheng, H. He, and B. Chen, "Catalytic pyrolysis of wheat straw based on dual catalyst CaO/ZSM-5 with acid washing and torrefaction pretreatment to enhance aromatic yield in bio-oils," J. Energy Inst., vol. 117, p.101836, Dec. 2024.

DOI: 10.1016/j.joei.2024.101836

[18] M. Yang, G. Chang, W. Cui, P. Ni, Q. Yi, L. Yang, C. Wang, In situ hydrodeoxygenation of heavy bio-oil using a Ce/Fe-based oxygen carrier in methanol-zero valent aluminum media. Chemosphere. 2024 Mar 1;352:141338.

DOI: 10.1016/j.chemosphere.2024.141338

[19] C. Zhou, Y. Chen, X. Xing, L. Chen, C. Liu, L. Chao, B. Yao, Y. hang, J. Dai, Y. Liu, J. Wang, Pilot-scale pyrolysis and activation of typical biomass chips in an interconnected dual fluidized bed: Comparison and analysis of products. Renewable Energy. 2024 May 1;225:120339.

DOI: 10.1016/j.renene.2024.120339

[20] Y. Yang, C. Miao, R. Wang, R. Zhang, X. Li, J. Wang, X. Wang, J. Yao, Advances in morphology-controlled alumina and its supported Pd catalysts: synthesis and applications. Chemical Society Reviews. 2024;53(10):5014-53.

DOI: 10.1039/d3cs00776f

[21] M. Gómez, J. Pizarro, X. Castillo, C. Díaz, A. Ghisolfi, M. de Lourdes Chávez, D. Cazorla-Amorós, J. Arenas-Alatorre, Preparation of mesoporous γ-Al2O3 with high surface area from an AlOOH extract of recycling biomass ash. Journal of Environmental Chemical Engineering. 2021 Oct 1;9(5):105925.

DOI: 10.1016/j.jece.2021.105925

[22] B. Li, C. F. Magoua Mbeugang, Y. Huang, D. Liu, Q. Wang, and S. Zhang, "A review of CaO based catalysts for tar removal during biomass gasification," Energy, vol. 244, p.123172, Apr. 2022.

DOI: 10.1016/j.energy.2022.123172

[23] G. Shi, J. Cheng, J. Wang, S. Zhang, X. Shao, X. Chen, X. Li, B. Xin, A comprehensive review of full recycling and utilization of cathode and anode as well as electrolyte from spent lithium-ion batteries. Journal of Energy Storage. 2023 Nov 25;72:108486.

DOI: 10.1016/j.est.2023.108486

[24] M. Huang, L. Zhu, Z. Ma, and Y. Yang, "Highly selective production of light aromatics from lignin through integrated approach of the torrefaction deoxygenation pretreatment and the dual-catalyst catalytic fast pyrolysis using Nb modified γ-Al2O3 and HZSM-5," Fuel, vol. 354, p.129318, Dec. 2023.

DOI: 10.1016/j.fuel.2023.129318

[25] A. P. Bebyakina, M. I. Farid, A. V. Boretskaya, S. R. Egorova, and A. A. Lamberov, "Commercial Aluminum Hydroxides. Part 1: Phase Composition and Textural Characteristics of Commercial Aluminum Hydroxides/Oxides," Catal. Ind., vol. 16, no. 4, p.363–371, Dec. 2024.

DOI: 10.1134/S207005042470020X

[26] T.S. da Silva, L.L. da Silva, E.P. da Silva, R.J. Motta, B.J. da Silva, M.R. Meneghetti, L. Meili, S.M. Meneghetti, From Waste to Catalyst: The Properties of Mixed Oxides Derived from Layered Double Hydroxide Mg/Al Synthesized from Aluminum Residues and Their Use in Transesterification. Reactions. 2025 May 10;6(2):33.

DOI: 10.3390/reactions6020033

[27] V. G. Baldovino-Medrano, V. Niño-Celis, and R. Isaacs Giraldo, "Systematic Analysis of the Nitrogen Adsorption–Desorption Isotherms Recorded for a Series of Materials Based on Microporous–Mesoporous Amorphous Aluminosilicates Using Classical Methods," J. Chem. Eng. Data, vol. 68, no. 9, p.2512–2528, Sep. 2023.

DOI: 10.1021/acs.jced.3c00257

[28] X. Wang, S. Guo, P. Song, L. Xu, X. Zhang, and B. Shen, "Synthesis and catalytic performance of hierarchically porous catalysts during pyrolysis of lipids to produce liquid hydrocarbons: A review," Appl. Catal. A Gen., vol. 677, p.119704, May 2024.

DOI: 10.1016/j.apcata.2024.119704

[29] M. L. Dieuzeide, R. de Urtiaga, M. Jobbagy, and N. Amadeo, "Vapor phase hydrogenolysis of glycerol to 1,2-propanediol at atmospheric pressure over copper catalysts supported on mesoporous alumina," Catal. Today, vol. 296, p.19–25, Nov. 2017.

DOI: 10.1016/j.cattod.2017.05.095

[30] A. H. Razm, A. Salem, and S. Salem, "Industrial performance, reusability and mechanical reliability of mesoporous gamma alumina packed bed fabricated through boehmite extrusion for removal of reactive dyes from textile wastewaters," J. Hazard. Mater., vol. 429, p.128259, May 2022.

DOI: 10.1016/j.jhazmat.2022.128259