Optimum Biodiesel Production from Palm Kernel Oil Using Heterogeneous Catalyst from Carbide Slag and Termite Hill Clay

This study is aimed at optimizing biodiesel production from palm kernel oil (PKO), using heterogeneous catalyst made from carbide slag and termite hill clay. The precursors (carbide slag and termite hill clay) were prepared and characterized. The composite catalyst was doped with Zn(NO3)2 by wet impregnation method. The PKO was characterized to obtain its different properties. Design of Experiments (DOE) was systematically used to study the effects of different variables on biodiesel yield and to ascertain the ideal conditions for optimum yield. The modelling was limited to RSM, using Box-Behnken design. The PKO’s acid value, saponification value, average molecular weight, density, viscosity, moisture content, iodine value and peroxide value were obtained as 7.34 mgKOH/g oil, 234.18 mgKOH/g oil, 741.93 g/mol, 0.901 g/cm3, 4.7 mPa.s, 1.09%, 18.7 mg I2/100g oil and 16.2 mEq/kg respectively. The XRF results showed that the carbide slag contained 89.763% CaO, 4.036 % SiO2, 3.880 % Al2O3, etc., while the THC contained 46.924% SiO2, 24.144% Al2O3, 20.619 % Fe2O3, etc. The composite contained the required oxides for carrying out esterification and transesterification process simultaneously. The yield was observed to be significantly impacted by all the factors. RSM numerical optimization gave an optimum yield of 98.22% at 66.95 oC, 94.04 minutes, 11.98:1 alcohol/oil ratio, and 2.39 wt% catalyst loading. There was an overall reduction of 28.4% in yield between the first and sixth reactions, for the catalyst reusability studies, which catalysed six different reactions. The produced biodiesel was characterized and the properties were found to be in agreement with the ASTM D6571 and EN 14214 standards.

Palm kernel oil, Carbide slag, Termite hill clay

1. Ajala, E. O., Ehinmowo, A. B., Ajala, M. A., Ohiro, O. A., Aderibigbe, F. A., & Ajao, A. O. (2022). Optimisation of CaO-Al2O3-SiO2-CaSO4-based catalysts performance for methanolysis of waste lard for biodiesel production using response surface methodology and meta-heuristic algorithms. Fuel Processing Technology, 226, 107066. [Google Scholar] [Crossref]

2. Al-Sakkari, E. G., El-Sheltawy, S. T., Attia, N. K., & Mostafa, S. R. (2017). Kinetic study of soybean oil methanolysis using cement kiln dust as a heterogeneous catalyst for biodiesel production. Applied Catalysis B: Environmental, 206, 146–157. https://doi.org/10.1016/j.apcatb.2017.01.008 [Google Scholar] [Crossref]

3. Alagha, S. M., & Salih, R. (2023). Review the studies of mass transfer and kinetic modeling for production the biodiesel by the transesterification method and the impact of some selected factors Review the studies of mass transfer and kinetic modeling for production the biodiesel by the tr. IOP Conference Series: Earth and Environmental Science. https://doi.org/10.1088/1755-1315/1232/1/012014 [Google Scholar] [Crossref]

4. Amenaghawon, A. N., Obahiagbon, K., Isesele, V., & Usman, F. (2022). Optimized biodiesel production from waste cooking oil using a functionalized bio-based heterogeneous catalyst. Cleaner Engineering and Technology, 8, 100501. https://doi.org/10.1016/j.clet.2022.100501 [Google Scholar] [Crossref]

5. Anusha, P., Janeefa, P., Gangadhara, R., & T, S. R. (2021). Biodiesel Preparation , Process Optimization and Characterization from Neem seed Oil. Int J Res Appl Sci Eng Technol, 9(10), 525–527. [Google Scholar] [Crossref]

6. Aremanda, R. B., Tekleweyni, D., Arebu, M., Fufa, G., & Nasir, M. (2025). Influence of Methanol Solvent and Alkali Catalyst on Biodiesel Production from Cottonseed Oil. International Journal of Energetica, 10(1), 24–30. [Google Scholar] [Crossref]

7. Balajii, M., & Niju, S. (2019). Biochar ‑ derived heterogeneous catalysts for biodiesel production. Environmental Chemistry Letters, 17(4), 1447–1469. https://doi.org/10.1007/s10311-019-00885-x [Google Scholar] [Crossref]

8. Betiku, E., Akintunde, A. M., & Ojumu, T. V. (2016). Banana peels as a biobase catalyst for fatty acid methyl esters production using Napoleon’s plume (Bauhinia monandra) seed oil: A process parameters optimization study. Energy, 103, 797–806. https://doi.org/10.1016/j.energy.2016.02.138 [Google Scholar] [Crossref]

9. Biru Birhanu, Devendra Deshmukh, T. H. and K. Y. (2025). RSM-Optimized Biodiesel Production from Ethiopian Podocarpus falcatus Seed Oil Using a CaO-CeO₂ Stability Assessment Meaning IN IN. Scientific Reports. [Google Scholar] [Crossref]

10. Çapa, T., Bahç, B., & Abdeljelil, B. Ben. (2023). Assessment of Homogeneous and Heterogeneous Catalysts in Transesterification Reaction : A Mini Review. ChemBioEng, 4, 412–422. https://doi.org/10.1002/cben.202200021 [Google Scholar] [Crossref]

11. Chumuang, N., & Punsuvon, V. (2017). Response Surface Methodology for Biodiesel Production Using Calcium Methoxide Catalyst Assisted with Tetrahydrofuran as Cosolvent. 14(1), 4190818. [Google Scholar] [Crossref]

12. Cordeiro, D. O., Silva, J. E., Oliveira, A. A. S., Batista, W. G. S., & Neto, E. L. B. (2019). Influence Of Carbonation And Rehydration On Cao Derived From Calcining Chicken Eggshells In The Catalytic Process Of Soybean. Brazillian Journal of Petroleum and Gas, 13(1), 5419. [Google Scholar] [Crossref]

13. Dolvine, N., Dongmo, S., Bruno, L., Meme, L., & Tongnang, N. (2024). Biodiesel Production From High FFA Raphia vinifera Oil as a Potential Non-edible Feedstock : Process Optimization Using Response Surface Methodology. Chemistry Africa, 7(3), 1481–1496. https://doi.org/10.1007/s42250-023-00814-0 [Google Scholar] [Crossref]

14. Donald, P., Sanchez, C., Hashim, N., Shamsudin, R., & Mohd, M. Z. (2021). Effects of different storage temperatures on the quality and shelf life of Malaysian sweet potato ( Ipomoea Batatas L . ) varieties. Food Packaging and Shelf Life, 28(October 2020), 100642. https://doi.org/10.1016/j.fpsl.2021.100642 [Google Scholar] [Crossref]

15. Ehiri, R. C. (2010). Determination of optimal methanol: oil volume ratio for maximum biodiesel production from waste cooking oil. Journal of Physical Sciences and Innovation, 2(December), 7–10. [Google Scholar] [Crossref]

16. Gibreel, O. H. O. (2022). Potential of Biodiesel Production from Waste Cooking Oil in Qatar: Techno-Economic Study. In (Doctoral dissertation, Manara-Qatar Research Repository). [Google Scholar] [Crossref]

17. Glass, S., Santiago-cruz, H. A., Chen, W., Zhang, T., Guelfo, J., Rittmann, B., Senftle, T. P., Vikesland, P., Villagrán, D., Wang, H., Westerhoff, P., Wong, M. S., Jiang, G., Lowry, G. V, & Alvarez, P. J. J. (2025). Merits , limitations and innovation priorities for heterogeneous catalytic platforms to destroy PFAS. Nature Water, 3(6), 644–654. https://doi.org/10.1038/s44221-025-00433-8 [Google Scholar] [Crossref]

18. Gonçalves, M. A., Cristina, H., Maria, P., & Paula, A. (2024). Catalytic conversion of residual raw material into biodiesel using a superior magnetic solid acid catalyst based on Zn – Fe ferrite : thermodynamic and kinetic studies. Royal Society of Chemistry, 14, 20743–20756. https://doi.org/10.1039/d4ra03580a [Google Scholar] [Crossref]

19. Gupta, V., & Singh, K. P. (2023). The impact of heterogeneous catalyst on biodiesel production ; a review. Materials Today: Proceedings, 78, 364–371. [Google Scholar] [Crossref]

20. Ifeanyi-Nze, F. O., Omiyale, C. O., & Okonkwo, I. U. (2023). Biodiesel Synthesis from Waste Vegetable Oil Utilizing Eggshell Ash as an Innovative Heterogeneous Catalyst. Archives of Advanced Engineering Science, 1–18. https://doi.org/10.47852/bonviewAAES32021761 [Google Scholar] [Crossref]

21. Indrianty, I. A., & Muchtar, M. (2024). Utilization Of used oil into biodiesel by using duck bone catalyst to meet the needs of diesel fuel review. In BIO Web of Conferences, 123, 04006. https://doi.org/https://doi.org/10.1051/bioconf/202412304006 [Google Scholar] [Crossref]

22. Jambhulkar, D. K., Ugwekar, R. P., Bhanvase, B. A., & Divya, P. (2020). A review on solid base heterogeneous catalysts : preparation , characterization and applications. Chemical Engineering Communications, 209(4), 433–484. https://doi.org/10.1080/00986445.2020.1864623 [Google Scholar] [Crossref]

23. Javed, F., Rizwan, M., Asif, M., Ali, S., Aslam, R., Akram, M. S., Zimmerman, W. B., & Rehman, F. (2022). Intensification of Biodiesel Processing from Waste Cooking Oil , Exploiting Cooperative Microbubble and Bifunctional Metallic Heterogeneous Catalysis. Bioengineering, 9(10), 533. https://doi.org/10.3390/bioengineering9100533 [Google Scholar] [Crossref]

24. Khoobbakht, G., Kheiralipour, K., Rasouli, H., & Ra, M. (2020). Experimental exergy analysis of transesterification in biodiesel production. Energy, 196, 117092. https://doi.org/https://doi.org/10.1016/j.energy.2020.117092 [Google Scholar] [Crossref]

25. Kingkam, W., Maisomboon, J., Khamenkit, K., Nuchdang, S., Nilgumhang, K., Issarapanacheewin, S., & Rattanaphra, D. (2024). Preparation of CaO @ CeO 2 Solid Base Catalysts Used for Biodiesel Production. Catalysts, 14(4), 240. [Google Scholar] [Crossref]

26. Komadel, P. (2016). Acid activated clays : Materials in continuous demand. Applied Clay Science, 131, 84–99. https://doi.org/10.1016/j.clay.2016.05.001 [Google Scholar] [Crossref]

27. Krödel, M., Leroy, C., Kim, S. M., Naeem, M. A., Kierzkowska, A., Wu, Y.-H., Armutlulu, A., Fedorov, A., Florian, P., & Müller, C. R. (2023). Of Glasses and Crystals: Mitigating the Deactivation of CaO-Based CO 2 Sorbents through Calcium Aluminosilicates. Journal of the American Chemical Society, 3, 3111–3126. https://doi.org/10.1021/jacsau.3c00475\ [Google Scholar] [Crossref]

28. Kumar, S. A. A., Sakthinathan, G., Vignesh, R., Banu, J. R., & Al-muhtaseb, A. H. (2019). Optimized transesterification reaction for efficient biodiesel production using Indian oil sardine fish as feedstock. Fuel, 253, 921–929. https://doi.org/10.1016/j.fuel.2019.04.172 [Google Scholar] [Crossref]

29. Li, M., Chen, J., Li, L., Ye, C., Lin, X., & Qiu, T. (2021). ScienceDirect Novel multi – SO 3 H functionalized ionic liquids as highly efficient catalyst for synthesis of biodiesel. Green Energy and Environment, 6(2), 271–282. https://doi.org/10.1016/j.gee.2020.05.004 [Google Scholar] [Crossref]

30. LibreTexts. (2022). Infrared Spectroscopy Absorption Table (p. 22645). https://chem.libretexts.org/@go/page/22645%0A [Google Scholar] [Crossref]

31. Malabadi, R. B. (2023). Biodiesel production: An updated review of evidence. International Journal of Biological and Pharmaceutical Sciences Archive, 2023, 06 (02), 110–133. [Google Scholar] [Crossref]

32. Malabadi, R. B., Sadiya, M. R., Kolkar, K. P., & Chalannavar, R. K. (2023). Biodiesel production via transesterification reaction. Open Access Research Journal of Science and Technology, 9(2), 010–021. https://doi.org/10.53022/oarjst.2023.9.2.0064 [Google Scholar] [Crossref]

33. Mandari, V., & Kumar, S. (2022). Biodiesel Production Using Homogeneous , Heterogeneous , and Enzyme Catalysts via Transesterification and Esterification Reactions : a Critical Review. BioEnergy Research, 15(2), 935–961. https://doi.org/10.1007/s12155-021-10333-w [Google Scholar] [Crossref]

34. Mardhiah, H. H., Ong, H. C., Masjuki, H. H., Lim, S., & Lee, H. V. (2017). A review on latest developments and future prospects of heterogeneous catalyst in biodiesel production from non-edible oils. Renewable and Sustainable Energy Reviews, 67, 1225–1236. https://doi.org/10.1016/j.rser.2016.09.036 [Google Scholar] [Crossref]

35. Masango, S. B., Ngema, P. T., & Olagunju, O. A. (2024). The Effect of Reaction Temperature , Catalyst Concentration and Alcohol Ratio in the Production of Biodiesel from Raw and Purified Castor Oil. Advances in Chemical Engineering and Science, 14, 137–154. https://doi.org/10.4236/aces.2024.143009 [Google Scholar] [Crossref]

36. Mohamed, S., Aghareed, F., Shereen, M. T., Hamid, M. S. A., & Osman, R. M. (2024). Recent advances in transesterification for sustainable biodiesel production , challenges , and prospects : a comprehensive review. Environmental Science and Pollution Research, 31(9), 12722–12747. https://doi.org/10.1007/s11356-024-32027-4 [Google Scholar] [Crossref]

37. Monika, Pathak, V. V., & Banga, S. (2026). A comprehensive analysis of refining technologies for biodiesel purification. Brazilian Journal of Chemical Engineering, 1–17. [Google Scholar] [Crossref]

38. Montgomery, D. C. (2017). Design and analysis of experiments (Ninth Edit). John Wiley & Sons. [Google Scholar] [Crossref]

39. Nair, A. T., Makwana, A. R., & Ahammed, M. M. (2018). The use of response surface methodology for modelling and analysis of water and wastewater treatment processes : a review. November, 464–478. https://doi.org/10.2166/wst.2013.733 [Google Scholar] [Crossref]

40. Narasimharao, K., Mostafa, M. M. M., Al-amshany, Z. M., & Bajafar, W. (2023). Mechanochemical Synthesized CaO/ZnCo 2 O 4 Nanocomposites for Biodiesel Production. Catalysts, 13(2), 398. [Google Scholar] [Crossref]

41. Nawin, L., Kumar, M., & Thakur, C. (2024). Application of Catalysts Used in Biodiesel Production - A Review. Journal of Environmental Nanotechnology, 13(3), 145–151. [Google Scholar] [Crossref]

42. Odisu, T., Akemu, A., Obahiagbon, K. O. ., & Anih, E. C. (2019). Comparative Studies on the Production of Biodiesel from Shea Nut Oil by Acid Catalyzed and Supercritical Transesterification Processes. Appl. Sci. Environmental Management., 23(2), 349–357. https://doi.org/https://dx.doi.org/10.4314/jasem.v23i2.23 [Google Scholar] [Crossref]

43. Okoduwa, I. G., Oiwoh, O., Amenaghawon, A. N., & Okieimen, C. O. (2025). A biobased mixed metal oxide catalyst for biodiesel production from waste cooking oil: reaction conditions modeling, optimization and sensitivity analysis study. Journal of Engineering Research (Kuwait), 13(2), 1344–1357. https://doi.org/10.1016/j.jer.2024.03.009 [Google Scholar] [Crossref]

44. Olubunmi, B. E., Karmakar, B., Aderemi, O. M., G, A. U., Auta, M., & Halder, G. (2020). Journal of Environmental Chemical Engineering Parametric optimization by Taguchi L9 approach towards biodiesel production from restaurant waste oil using Fe-supported anthill catalyst. Journal of Environmental Chemical Engineering, 8(5), 104288. https://doi.org/10.1016/j.jece.2020.104288 [Google Scholar] [Crossref]

45. Osorio-Tejada, J. L., Llera-Sastresa, E., & Scarpellini, S. (2017). A multi-criteria sustainability assessment for biodiesel and liquefied natural gas as alternative fuels in transport systems. Journal of Natural Gas Science and Engineering, 42, 169–186. https://doi.org/10.1016/j.jngse.2017.02.046 [Google Scholar] [Crossref]

46. Patiño, Y., Faba, L., Peláez, R., Cueto, J., Marín, P., Díaz, E., & Ordóñez, S. (2023). The Role of Ion Exchange Resins for Solving Biorefinery Catalytic Processes Challenges. Catalysts, 13(6), 999. [Google Scholar] [Crossref]

47. Qader, D. N., Jamil, A. S., Bahrami, A., Ali, M., & Arunachalam, K. P. (2025). A systematic review of metakaolin-based alkali- activated and geopolymer concrete : A step toward green concrete. Reviews on Advanced Materials Science, 64(1), 20240076. [Google Scholar] [Crossref]

48. Qurashi, F., Sial, S. A., & Qureshi, H. H. (2026). Recent developments in biodiesel synthesis from agricultural wastes : A comprehensive review of feedstocks , catalysts , and machine learning approaches. SciNex Journal of Advanced Sciences., 1(01), 202510060007–202510060007. https://doi.org/10.sjas.202510060007 [Google Scholar] [Crossref]

49. Ramesh, M., Praveen, S., Kuppuswamy, N., Khan, A., & Asiri, A. M. (2021). Biodiesel production from waste cooking oil using ionic liquids as catalyst. Advanced Technology for the Conversion of Waste into Fuels and Chemicals: Volume 1: Biological Processes, 91, 215–230. https://doi.org/10.1016/B978-0-12-823139-5.00005-8 [Google Scholar] [Crossref]

50. Rezania, S., Sotoudehnia, Z., Ali, M., Cho, J., Kumar, K., Cabral-pinto, M. M. S., Alam, J., Ahamed, M., & Rashidi, H. (2021). Lanthanum phosphate foam as novel heterogeneous nanocatalyst for biodiesel production from waste cooking oil. Renewable Energy, 176, 228–236. https://doi.org/10.1016/j.renene.2021.05.060 [Google Scholar] [Crossref]

51. Rizwanul Fattah, I. M., Ong, H. C., Mahlia, T. M. I., Mofijur, M., Silitonga, A. S., Ashrafur Rahman, S. M., & Ahmad, A. (2020). State of the Art of Catalysts for Biodiesel Production. Frontiers in Energy Research, 8, 101. https://doi.org/10.3389/fenrg.2020.00101 [Google Scholar] [Crossref]

52. Satriadi, H., Setyojati, P. W., Shihab, D., Buchori, L., Hadiyanto, H., & Nurushofa, F. A. (2024). Preparation CaO / MgO / Fe 3 O 4 magnetite catalyst and catalytic test for biodiesel production. Results in Engineering, 22, 102202. https://doi.org/10.1016/j.rineng.2024.102202 [Google Scholar] [Crossref]

53. Singh, D., Singh, K., Jadeja, Y., Menon, S. V, Singh, P., Ibrahim, S. M., & Singh, M. (2025). Magnetic nano-sized solid acid catalyst bearing sulfonic acid groups for biodiesel synthesis and oxidation of sulfides. Scientific Reports, 15, 1397. https://doi.org/https://doi.org/10.1038/s41598-024-84494-x [Google Scholar] [Crossref]

54. Sisca, V., Zilfa, Jamarun, N., & Tanjung, D. A. (2025). Catalytic innovation for renewable energy: TiO₂-supported precipitated calcium carbonate catalyst for biodiesel synthesis. Baghdad Science Journal, 22(3), 11692. [Google Scholar] [Crossref]

55. Sun, J., Chen, H., Shen, H., Luo, X., & Lin, Z. (2026). Optimization of Biodiesel Production from Waste Cooking Oil Using a Construction Industry Waste Cement as a Heterogeneous and Reusable Catalyst. 16(2), 108. https://doi.org/https://doi.org/10.3390/nano16020108 [Google Scholar] [Crossref]

56. Suryanto, A., Kalsum, R. R. U., Munira, M., Syahrir, M., & Falah, N. N. I. A. (2025). Evaluation of Potassium Carbonate-Impregnated Alumina Catalyst In Batch Biodiesel Production From Castor Oil. International Journal on Technical and Physical Problems of Engineering (IJTPE), 17, 144–150.\ [Google Scholar] [Crossref]

57. Suwanthai, W., Punsuvon, V., & Vaithanomsat, P. (2016). Optimization of biodiesel production from a calcium methoxide catalyst using a statistical model. Korean Journal of Chemical Engineering, 33(1), 90–98. https://doi.org/10.1007/s11814-015-0096-9 [Google Scholar] [Crossref]

58. Tang, C. F., Tan, B. W., & Ozturk, I. (2016). Energy consumption and economic growth in Vietnam. Renewable and Sustainable Energy Reviews, 54, 1506–1514. https://doi.org/10.1016/j.rser.2015.10.083 [Google Scholar] [Crossref]

59. Tien, T., Kee, M., Wang, Y., Loke, P., Shi, I., & Lim, S. (2021). Reaction kinetic and thermodynamics studies for in-situ transesterification of wet microalgae paste to biodiesel. Chemical Engineering Research and Design, 169, 250–264. https://doi.org/10.1016/j.cherd.2021.03.021 [Google Scholar] [Crossref]

60. Turcu, E., Coromelci, C. G., Harabagiu, V., & Ignat, M. (2023). Enhancing the photocatalytic activity of TiO2 for the degradation of congo red dye by adjusting the ultrasonication regime applied in its synthesis procedure. Catalysts, 13(2), 345. [Google Scholar] [Crossref]

61. Ulukardesler, A. H. (2023). Biodiesel Production from Waste Cooking Oil Using Different Types of Catalysts. Processes, 11(7), 2035. https://doi.org/https://doi.org/10.3390/pr11072035 [Google Scholar] [Crossref]

62. Vakhitova, Z. I., & Alston-Knox, C. L. (2018). Non-significant p-values? Strategies to understand and better determine the importance of effects and interactions in logistic regression. PLoS ONE, 13(11), e0205076. https://doi.org/10.1371/journal.pone.0205076 [Google Scholar] [Crossref]

63. Wang, B., Wang, B., Shukla, S. K., & Wang, R. (2023). Enabling Catalysts for Biodiesel Production. Catalysts, 13(4), 740. https://doi.org/https://doi.org/10.3390/catal13040740 [Google Scholar] [Crossref]

64. Yaghi, M., Chidiac, S., Awad, S., Rayess, Y. El, & Zgheib, N. (2025). An Overview of Biodiesel Production via Heterogeneous Catalysts : Synthesis , Current Advances , and Challenges. Clean Technologies, 7(3), 62. https://doi.org/10.3390/cleantechnol7030062 [Google Scholar] [Crossref]

65. Yang, G., & Yu, J. (2023). Advancements in Basic Zeolites for Biodiesel Production via Transesterification. Chemistry, 5(1), 438–451. https://doi.org/10.3390/chemistry5010032 [Google Scholar] [Crossref]

66. Yesilyurt, M. K., Cesur, C., Aslan, V., & Yilbasi, Z. (2020). The production of biodiesel from safflower (Carthamus tinctorius L.) oil as a potential feedstock and its usage in compression ignition engine: A comprehensive review. Renewable and Sustainable Energy Reviews, 119(109574). https://doi.org/10.1016/j.rser.2019.109574 [Google Scholar] [Crossref]

67. Yusuff, A. S., Gbadamosi, A. O., & Popoola, L. T. (2021). Journal of Environmental Chemical Engineering Biodiesel production from transesterified waste cooking oil by zinc-modified anthill catalyst : Parametric optimization and biodiesel properties improvement. Journal of Environmental Chemical Engineering, 9(2), 104955. https://doi.org/10.1016/j.jece.2020.104955 [Google Scholar] [Crossref]

68. Zaera, F. (2022). Designing Sites in Heterogeneous Catalysis : Are We Reaching Selectivities Competitive With Those of Homogeneous Catalysts ? Chemical Reviews, 122(9), 8594–8757. https://doi.org/10.1021/acs.chemrev.1c00905 [Google Scholar] [Crossref]

69. Zaman, K., & Moemen, M. A. el. (2017). Energy consumption, carbon dioxide emissions and economic development: Evaluating alternative and plausible environmental hypothesis for sustainable growth. Renewable and Sustainable Energy Reviews, 74, 1119–1130. https://doi.org/10.1016/j.rser.2017.02.072 [Google Scholar] [Crossref]

70. Zhang, Y., Niu, S., Han, K., Li, Y., & Lu, C. (2021). Synthesis of the SrO–CaO–Al2O3 trimetallic oxide catalyst for transesterification to produce biodiesel. Renewable Energy, 168, 981–990. https://doi.org/10.1016/j.renene.2020.12.132 [Google Scholar] [Crossref]

71. Zhang, Y., Li, X., Wang, H., & Chen, Y. (2025). Enhanced anti-sintering performance of metakaolin incorporated CaO adsorbents for CO₂ capture. Journal of Environmental Chemical Engineering, 13, 118734. https://doi.org/10.1016/j.jece.2025.118734 [Google Scholar] [Crossref]

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