生質柴油是替代能源發展的重要目標，以SrO作為轉酯化催化劑具有優異的催化效能，製備為負載式催化劑能夠進一步增加重複使用性及反應表面積。本研究以鈦板作為載體透過溶膠凝膠法製備SrO/TiO2_P催化劑，利用XPS及XRD分析確認試片表面SrO以及SrTiO3中間相化合物的沉積，在ASTM D3359膠帶測試中達到3B等級，並以表面輪廓儀分析儀得到試片表面粗糙度為1780.4 nm。在批次式系統以橄欖油及廢食用油為原料進行試片的重複轉酯化，並透過簡單的回收步驟將反應後的試片進行表面清潔，結果得到試片能夠重複用於橄欖油轉酯化三次，以廢食用油為原料則能夠重複使用兩次，此外，還發現以廢食用油為原料會得到較低的產物轉酯率，這是因為廢食用油中較高的游離脂肪酸與水分會阻礙轉酯化反應的發生；將試片應用於連續流系統中進行廢食用油的轉酯化反應，結果顯示較高的原料流速會導致產物轉酯率的降低，而當原料的流速為60及70 mL/min時，產物的轉酯率有較高的79.5與77.2 %。將兩個系統中反應得到的產物進行品質分析，生質柴油的平均燃燒熱為39.32 MJ/kg，符合文獻中39到41 MJ/kg的敘述；含水率以橄欖油為原料是0.0364 vol%，以廢食用油為原料則是0.0413 及0.0443 vol%，符合ASTM D6751提供的標準。
綜上所述，SrO/TiO2_P能夠利用廢食用油作為原料進行生質柴油的製備，符合循環經濟的理念，並且試片在批次式系統中可以被重複使用最多三次，驗證了試片作為負載式催化劑具有重複使用性；結合微波加熱的連續流系統進行廢食用油轉酯化，能夠達到接近80 %轉酯率的同時大幅提升反應效率，並且得到的產物其燃燒熱及含水率經過分析後符合標準，因此，SrO/TiO2_P有未來應用於工業生產之潛力。

In this work, Ti plate was used as the support to fabricate SrO-loaded catalyst for transesterification. The catalyst, denoted as SrO/TiO2_P, was studied on its recyclability for batch transesterification and the performance when applied in a continuous fluid flow system for waste cooking oil (WCO) transesterification. The deposition of SrO and the intermediate phase were confirmed using XRD and XPS. The decomposition of the precursor components were analyzed using TGA. Mechanical test of ASTM D3359 and Alpha step were also conducted to the SrO/TiO2_P. Under batch system, the decreasing in biodiesel conversion rate with repeated use of the catalysts was observed. This was caused by the gradual coverage of SrO by the raw materials and products. With the standard of 50 % biodiesel conversion rate referring to literatures, the catalyst showed a recycle time of two cycles for WCO transesterification. In the continuous fluid flow system, 77.2 % of biodiesel conversion rate was achieved and the reaction efficiency was found to be 2.8 times higher than that of batch system at a flow velocity of 70 mL/min. This improvement was attributed to the enhanced mixing capability and greater energy of raw materials in the continuous fluid flow system. The produced biodiesel was analyzed to possess a combustion heat of 39.22 MJ/kg and a water content of less than 0.05 vol%, which met the ASTM D6751 standard. These results suggested that the SrO/TiO2_P catalyst could be reused for WCO transesterification under batch system. When applied in the continuous fluid flow system, a significant improvement in reaction efficiency could be observed, and the quality of resulting product met the standard. Therefore, SrO/TiO2_P had the potential for industrial production of biodiesel.

[1] O. C. Eneh, "A review on petroleum: source, uses, processing, products, and the environment," Journal of Applied Sciences, 2011.
[2] A. Azad, M. Rasul, M. Khan, T. Ahasan, and S. Ahmed, "Energy scenario: production, consumption and prospect of renewable energy in Australia," Journal of power and Energy Engineering, 2014.
[3] A. Demirbas, "Biofuels securing the planet’s future energy needs," Energy conversion and management, 2009.
[4] W. Shi, J. Li, B. He, F. Yan, Z. Cui, K. Wu, L. Lin, X. Qian, and Y. Cheng, "Biodiesel production from waste chicken fat with low free fatty acids by an integrated catalytic process of composite membrane and sodium methoxide," Bioresource technology, 2013.
[5] I. Atadashi, M. K. Aroua, and A. A. Aziz, "High quality biodiesel and its diesel engine application: a review," Renewable and sustainable energy reviews, 2010.
[6] P. Benjumea, J. Agudelo, and A. Agudelo, "Basic properties of palm oil biodiesel–diesel blends," Fuel, 2008.
[7] A. Tangy, I. N. Pulidindi, A. Dutta, and A. Borenstein, "Strontium oxide nanoparticles for biodiesel production: fundamental insights and recent progress," Energy & Fuels, 2020.
[8] N. C. Neyt and D. L. Riley, "Application of reactor engineering concepts in continuous flow chemistry: a review," Reaction Chemistry & Engineering, 2021.
[9] P. Patil, V. G. Gude, S. Pinappu, and S. Deng, "Transesterification kinetics of Camelina sativa oil on metal oxide catalysts under conventional and microwave heating conditions," Chemical Engineering Journal, 2011.
[10] J. A. Tavizón-Pozos, G. Chavez-Esquivel, V. A. Suárez-Toriello, C. E. Santolalla-Vargas, O. A. Luévano-Rivas, O. U. Valdés-Martínez, A. Talavera-López, and J. A. Rodriguez, "State of art of alkaline earth metal oxides catalysts used in the transesterification of oils for biodiesel production," Energies, 2021.
[11] H. Li, S. Niu, C. Lu, and J. Li, "Calcium oxide functionalized with strontium as heterogeneous transesterification catalyst for biodiesel production," Fuel, 2016.
[12] H. Li, F. Liu, X. Ma, P. Cui, M. Guo, Y. Li, Y. Gao, S. Zhou, and M. Yu, "An efficient basic heterogeneous catalyst synthesis of magnetic mesoporous Fe@C support SrO for transesterification," Renewable Energy, 2019.
[13] H. Lee, J.-D. Liao, M. H. Lee, B. H. Liu, W.-E. Fu, K. Sivashanmugan, and Y.-D. Juang, "Strontium Oxide Deposited onto a Load-Bearable and Porous Titanium Matrix as Dynamic and High-Surface-Contact-Area Catalysis for Transesterification," Nanomaterials, 2018.
[14] A. Mukhtar, S. Saqib, H. Lin, M. U. Hassan Shah, S. Ullah, M. Younas, M. Rezakazemi, M. Ibrahim, A. Mahmood, S. Asif, and A. Bokhari, "Current status and challenges in the heterogeneous catalysis for biodiesel production," Renewable and Sustainable Energy Reviews, 2021.
[15] T. M. Mata, A. A. Martins, and N. S. Caetano, "Microalgae for biodiesel production and other applications: A review," Renewable and Sustainable Energy Reviews, 2010.
[16] D. Singh, D. Sharma, S. L. Soni, S. Sharma, P. Kumar Sharma, and A. Jhalani, "A review on feedstocks, production processes, and yield for different generations of biodiesel," Fuel, 2020.
[17] C. Haşimoğlu, M. Ciniviz, İ. Özsert, Y. İçingür, A. Parlak, and M. S. Salman, "Performance characteristics of a low heat rejection diesel engine operating with biodiesel," Renewable energy, 2008.
[18] A. Nomgboye and A. Hansen, "Prediction of cetane number of biodiesel fuel from the fatty acid methyl ester [FAME] composition," International Agrophysics, 2008.
[19] M. Mathiyazhagan and A. Ganapathi, "Factors affecting biodiesel production," Research in plant Biology, 2011.
[20] G. Knothe, J. Krahl, and J. Van Gerpen, The biodiesel handbook. Elsevier, 2015.
[21] M. I. Jahirul, M. G. Rasul, A. A. Chowdhury, and N. Ashwath, "Biofuels production through biomass pyrolysis—a technological review," Energies, 2012.
[22] P. Kalita, B. Basumatary, P. Saikia, B. Das, and S. Basumatary, "Biodiesel as renewable biofuel produced via enzyme-based catalyzed transesterification," Energy Nexus, 2022.
[23] A. Demirbas, "Progress and recent trends in biodiesel fuels," Energy Conversion and Management, 2009.
[24] P. B. L. Fregolente, L. V. Fregolente, and M. R. Wolf Maciel, "Water content in biodiesel, diesel, and biodiesel–diesel blends," Journal of chemical & engineering data, 2012.
[25] M. Stoytcheva and G. Montero, Biodiesel: feedstocks and processing technologies. BoD–Books on Demand, 2011.
[26] A. Demirbas, "A Realistic Fuel Alternative for Diesel Engines," ed: Springer London2008, 2007.
[27] M. K. Lam, K. T. Lee, and A. R. Mohamed, "Homogeneous, heterogeneous and enzymatic catalysis for transesterification of high free fatty acid oil (waste cooking oil) to biodiesel: a review," Biotechnology advances, 2010.
[28] O. Alamu, T. Akintola, C. Enweremadu, and A. Adeleke, "Characterization of palm-kernel oil biodiesel produced through NaOH-catalysed transesterification process," Scientific Research and Essay, 2008.
[29] G. Arzamendi, I. Campo, E. Arguinarena, M. Sánchez, M. Montes, and L. Gandia, "Synthesis of biodiesel with heterogeneous NaOH/alumina catalysts: comparison with homogeneous NaOH," Chemical Engineering Journal, 2007.
[30] K. Noiroj, P. Intarapong, A. Luengnaruemitchai, and S. Jai-In, "A comparative study of KOH/Al2O3 and KOH/NaY catalysts for biodiesel production via transesterification from palm oil," Renewable energy, 2009.
[31] A. Srivastava and R. Prasad, "Triglycerides-based diesel fuels," Renewable and sustainable energy reviews, 2000.
[32] N. U. Soriano Jr, R. Venditti, and D. S. Argyropoulos, "Biodiesel synthesis via homogeneous Lewis acid-catalyzed transesterification," Fue, 2009.
[33] M. Canakci and J. Van Gerpen, "Biodiesel production viaacid catalysis," Transactions of the ASAE, vol. 42, no. 5, p. 1203, 1999.
[34] B. Z. Dholakiya, "Super phosphoric acid catalyzed biodiesel production from low cost feed stock," Archives of Applied Science Research, 2012.
[35] S. Semwal, A. K. Arora, R. P. Badoni, and D. K. Tuli, "Biodiesel production using heterogeneous catalysts," Bioresource Technology, 2011.
[36] M. Di Serio, R. Tesser, L. Pengmei, and E. Santacesaria, "Heterogeneous catalysts for biodiesel production," Energy & Fuels, 2008.
[37] C. M. Garcia, S. Teixeira, L. L. Marciniuk, and U. Schuchardt, "Transesterification of soybean oil catalyzed by sulfated zirconia," Bioresource technology, 2008.
[38] H. Chen, B. Peng, D. Wang, and J. Wang, "Biodiesel production by the transesterification of cottonseed oil by solid acid catalysts," Frontiers of Chemical Engineering in China, 2007.
[39] Z. T. Alismaeel, A. S. Abbas, T. M. Albayati, and A. M. Doyle, "Biodiesel from batch and continuous oleic acid esterification using zeolite catalysts," Fuel, 2018.
[40] Y. C. Sharma, B. Singh, and J. Korstad, "Advancements in solid acid catalysts for ecofriendly and economically viable synthesis of biodiesel," Biofuels, Bioproducts and Biorefining, 2011.
[41] D. G. Cantrell, L. J. Gillie, A. F. Lee, and K. Wilson, "Structure-reactivity correlations in MgAl hydrotalcite catalysts for biodiesel synthesis," Applied Catalysis A: General, 2005.
[42] L. Gao, G. Teng, G. Xiao, and R. Wei, "Biodiesel from palm oil via loading KF/Ca–Al hydrotalcite catalyst," Biomass and Bioenergy, 2010.
[43] X. Liu, H. He, Y. Wang, S. Zhu, and X. Piao, "Transesterification of soybean oil to biodiesel using CaO as a solid base catalyst," Fuel, 2008.
[44] C. Xu, D. I. Enache, R. Lloyd, D. W. Knight, J. K. Bartley, and G. J. Hutchings, "Mgo catalysed triglyceride transesterification for biodiesel synthesis," Catalysis letters, 2010.
[45] A. Refaat, "Biodiesel production using solid metal oxide catalysts," International Journal of Environmental Science & Technology, 2011.
[46] S. Gryglewicz, "Rapeseed oil methyl esters preparation using heterogeneous catalysts," Bioresource Technology, 1999.
[47] X. Liu, H. He, Y. Wang, and S. Zhu, "Transesterification of soybean oil to biodiesel using SrO as a solid base catalyst," Catalysis Communications, 2007.
[48] M. Koberg, R. Abu-Much, and A. Gedanken, "Optimization of bio-diesel production from soybean and wastes of cooked oil: combining dielectric microwave irradiation and a SrO catalyst," Bioresource Technology, 2011.
[49] H. Lee, J.-D. Liao, J.-W. Yang, W.-D. Hsu, B. H. Liu, T.-C. Chen, K. Sivashanmugan, and A. Gedanken, "Continuous waste cooking oil transesterification with microwave heating and strontium oxide catalyst," Chemical Engineering & Technology, 2018.
[50] A. Tangy, I. N. Pulidindi, and A. Gedanken, "SiO2 beads decorated with SrO nanoparticles for biodiesel production from waste cooking oil using microwave irradiation," Energy & Fuels, 2016.
[51] H. Li, F. Liu, X. Ma, P. Cui, M. Guo, Y. Li, Y. Gao, S. Zhou, and M. Yu, "An efficient basic heterogeneous catalyst synthesis of magnetic mesoporous Fe@ C support SrO for transesterification," Renewable Energy, 2020.
[52] H. Lee, W.-H. Wu, B.-H. Chen, and J.-D. Liao, "Heterogeneous catalysts using strontium oxide agglomerates depositing upon titanium plate for enhancing biodiesel production," Catalysts, 2020.
[53] F. Pinna, "Supported metal catalysts preparation," Catalysis Today, 1998.
[54] V. Young and T. Otagawa, "XPS studies on strontium compounds," Applications of surface science, 1985.
[55] G. J. Owens, R. K. Singh, F. Foroutan, M. Alqaysi, C.-M. Han, C. Mahapatra, H.-W. Kim, and J. C. Knowles, "Sol–gel based materials for biomedical applications," Progress in materials science, 2016.
[56] J. M. N. van Kasteren and A. P. Nisworo, "A process model to estimate the cost of industrial scale biodiesel production from waste cooking oil by supercritical transesterification," Resources, Conservation and Recycling, 2007.
[57] S. Nomanbhay and M. Y. Ong, "A review of microwave-assisted reactions for biodiesel production," Bioengineering, 2017.
[58] M. Z. Duz, A. Saydut, and G. Ozturk, "Alkali catalyzed transesterification of safflower seed oil assisted by microwave irradiation," Fuel Processing Technology, 2011.
[59] P. Prafulla D, G. Veera Gnaneswar, R. Harvind K, M. Tapaswy, and D. Shuguang, "Biodiesel production from waste cooking oil using sulfuric acid and microwave irradiation processes," Journal of Environmental Protection, 2012.
[60] A. Refaat, S. El Sheltawy, and K. Sadek, "Optimum reaction time, performance and exhaust emissions of biodiesel produced by microwave irradiation," International Journal of Environmental Science & Technology, 2008.
[61] F. Ma and M. A. Hanna, "Biodiesel production: a review," Bioresource technology, 1999.
[62] M. Takase, M. Zhang, W. Feng, Y. Chen, T. Zhao, S. J. Cobbina, L. Yang, and X. Wu, "Application of zirconia modified with KOH as heterogeneous solid base catalyst to new non-edible oil for biodiesel," Energy Conversion and Management, 2014.
[63] S. Buddoo, N. Siyakatshana, and B. Pongoma, "Microreactors-a marvel of modern manufacturing technology: biodiesel case study," 2008.
[64] T. M. Barnard, N. E. Leadbeater, M. B. Boucher, L. M. Stencel, and B. A. Wilhite, "Continuous-flow preparation of biodiesel using microwave heating," Energy & Fuels, 2007.
[65] C. Carlucci, "An overview on the production of biodiesel enabled by continuous flow methodologies," Catalysts, 2022.
[66] A. Yokozeki and M. B. Shiflett, "The solubility of CO2 and N2O in olive oil," Fluid phase equilibria, 2011.
[67] I. M. Atadashi, M. K. Aroua, A. R. Abdul Aziz, and N. M. N. Sulaiman, "The effects of catalysts in biodiesel production: A review," Journal of Industrial and Engineering Chemistry, 2013.
[68] T. Ruppel, T. Huybrighs, and C. Shelton, "Fatty acid methyl esters in B100 biodiesel by gas chromatography (Modified EN 14103)," Perkin Elmer’s application note. Shelton. CT USA, 2008.
[69] M. E. Borges and L. Díaz, "Recent developments on heterogeneous catalysts for biodiesel production by oil esterification and transesterification reactions: A review," Renewable and Sustainable Energy Reviews, 2012.
[70] J. I. Orege, O. Oderinde, G. A. Kifle, A. A. Ibikunle, S. A. Raheem, O. Ejeromedoghene, E. S. Okeke, O. M. Olukowi, O. B. Orege, and E. O. Fagbohun, "Recent advances in heterogeneous catalysis for green biodiesel production by transesterification," Energy Conversion and Management, 2022.
[71] M. M. Barbooti and D. A. Al-Sammerrai, "Thermal decomposition of citric acid," Thermochimica acta, 1986.
[72] F. Granados-Correa and J. Bonifacio-Martínez, "Combustion synthesis process for the rapid preparation of high-purity SrO powders," Materials Science-Poland, 2014.
[73] T. Fu, C. S. Wen, J. Lu, Y. M. Zhou, S. G. Ma, B. H. Dong, and B. G. Liu, "Sol-gel derived TiO2 coating on plasma nitrided 316L stainless steel," Vacuum, 2012.
[74] H. F. McMurdie, M. C. Morris, E. H. Evans, B. Paretzkin, W. Wong-Ng, L. Ettlinger, and C. R. Hubbard, "Standard X-ray diffraction powder patterns from the JCPDS research associateship," Powder Diffraction, 1986.
[75] G. Welsch, R. Boyer, and E. Collings, Materials properties handbook: titanium alloys. ASM international, 1993.
[76] J.-D. Lin and Y.-C. Liu, "The preparation of SrSi2O2N2: Eu2+ and Sr2Si5N8: Eu2+ phosphors by a direct silicon nitridation process and Sr (NO3)2 as strontium and oxygen sources," Materials Chemistry and Physics, 2023.
[77] B. Hwang, R. Santhanam, and D. Liu, "Characterization of nanoparticles of LiMn2O4 synthesized by citric acid sol–gel method," Journal of power sources, 2001.
[78] M. M. S. Silva, M. S. Sena, A. L. Lopes-Moriyama, C. P. Souza, and A. G. Santos, "Experimental planning of the synthesis of strontium molybdate by EDTA-citrate and its structural influence, morphology and optical bandgap," Ceramics Internationa, 2018.
[79] C. Viornery, Y. Chevolot, D. Léonard, B.-O. Aronsson, P. Péchy, H. J. Mathieu, P. Descouts, and M. Grätzel, "Surface modification of titanium with phosphonic acid to improve bone bonding: characterization by XPS and ToF-SIMS," Langmui, 2002.
[80] R. Vasquez, "X-ray photoelectron spectroscopy study of Sr and Ba compounds," Journal of Electron Spectroscopy and Related Phenomena, 1991.
[81] U. Diebold and T. Madey, "TiO2 by XPS," Surface Science Spectra, 1996.
[82] C. Magdaleno-López and J. de Jesús Pérez-Bueno, "Quantitative evaluation for the ASTM D4541-17/D7234 and ASTM D3359 adhesion norms with digital optical microscopy for surface modifications with flame and APPJ," International Journal of Adhesion and Adhesives, 2020.
[83] Y. Li, S. Niu, J. Wang, W. Zhou, Y. Wang, K. Han, and C. Lu, "Mesoporous SrTiO3 perovskite as a heterogeneous catalyst for biodiesel production: Experimental and DFT studies," Renewable Energy, 2021.
[84] J. Montero, M. Isaacs, A. Lee, J. Lynam, and K. Wilson, "The surface chemistry of nanocrystalline MgO catalysts for FAME production: An in situ XPS study of H2O, CH3OH and CH3OAc adsorption," Surface science, 2016.
[85] H. Li, F. Liu, X. Ma, Z. Wu, Y. Li, L. Zhang, S. Zhou, and Y. Helian, "Catalytic performance of strontium oxide supported by MIL–100 (Fe) derivate as transesterification catalyst for biodiesel production," Energy Conversion and Management, 2019.
[86] R. Gopi, V. Thangarasu, and A. Ramanathan, "A critical review of recent advancements in continuous flow reactors and prominent integrated microreactors for biodiesel production," Renewable and Sustainable Energy Reviews, 2022.
[87] L. Dehghan, M.-T. Golmakani, and S. M. H. Hosseini, "Optimization of microwave-assisted accelerated transesterification of inedible olive oil for biodiesel production," Renewable Energy, 2019.
[88] C.-L. Chen, C.-C. Huang, D.-T. Tran, and J.-S. Chang, "Biodiesel synthesis via heterogeneous catalysis using modified strontium oxides as the catalysts," Bioresource Technology, 2012.
[89] R. Pena, R. Romero, S. L. Martinez, M. J. Ramos, A. Martinez, and R. Natividad, "Transesterification of castor oil: effect of catalyst and co-solvent," Industrial & Engineering Chemistry Research, 2009.
[90] S. Palitsakun, K. Koonkuer, B. Topool, A. Seubsai, and K. Sudsakorn, "Transesterification of Jatropha oil to biodiesel using SrO catalysts modified with CaO from waste eggshell," Catalysis Communications, 2020.
[91] W. Roschat, S. Phewphong, J. Khunchalee, and P. Moonsin, "Biodiesel production by ethanolysis of palm oil using SrO as a basic heterogeneous catalyst," Materials Today: Proceedings, 2018.