在現代航天和衛星技術中，推進劑的選擇和應用至關重要。液態推進劑由於其高能量密度、調控推力的靈活性以及使用方便性，被廣泛應用。其中液態單基推進劑則因其簡化的系統結構和低成本成為更為合適的選擇。聯胺是目前最常見的液態單基推進劑，但其高度腐蝕性和劇毒性質對環境和安全構成嚴重挑戰。為了克服聯胺的缺點，新一代具有低毒性、高效能、低環境影響和高安全性等特點的推進劑受到廣泛的關注，其中HAN基推進劑由於其高能量密度和相對低毒性，顯示出潛力在各種太空應用中取代傳統的高毒性推進劑。
然而，HAN基推進劑在無催化劑的情況下，其解離溫度較高並且反應速率緩慢，限制了其實際應用。而本研究著重在選出合適的催化劑配方作為未來推進器催化劑的使用，結果顯示六鋁酸鹽基催化劑可以顯著降低SHP163的解離溫度，並在低至150 ℃的溫度下仍保持催化效果，這顯示了催化劑在提升反應速率的重要性。
在新技術方面，電解解離點火技術作為一種重要的創新概念被引入，特別是應用於HAN基推進劑。電解解離點火不僅可以在室溫下進行無須預熱，而且能夠提供高效能的能量使用。這種技術通過電解過程中的離子水溶液特性，藉由施加電壓引發熱解離反應，從而達成推進器的點火目的。但其暫態的過程以及機制尚未明確，本研究主要成果在於成功建立電解模型進而解釋其暫態過程。
總結來說，液態單基推進劑特別是HAN基推進劑在現代航天技術中展現了巨大潛力。通過電解引燃等新技術的研究和應用，HAN 基推進劑可以克服傳統聯胺推進劑的缺點，提供更安全、高效和環保的推進解決方案。隨著技術的進一步發展，HAN 基推進劑有望在未來的太空探索和衛星推進中發揮更為重要的作用。

In modern aerospace and satellite technology, HAN-based propellants have garnered attention for their potential to replace traditional, highly toxic propellants in various space applications, owing to their high energy density and relatively low toxicity. However, the challenge lies in their high dissociation temperature and slow reaction rate without a catalyst. This study focuses on identifying a suitable catalyst formula for future propellant applications. The results demonstrate that hexaaluminate-based catalysts can significantly lower the dissociation temperature of SHP163 and maintain catalytic efficiency even at temperatures as low as 150 ℃. Recently, electrolytic dissociation ignition technology has emerged as a crucial innovation, particularly beneficial for HAN-based propellants. This method allows ignition at room temperature without the need for preheating, while maximizing energy efficiency. However, the transient process and underlying mechanisms of electrolytic dissociation ignition remain unclear. A significant achievement of this study is the successful development of an electrolysis model to elucidate these processes. In summary, liquid monopropellants, particularly HAN-based variants, hold substantial promise in modern aerospace technology. Through advancements like electrolytic ignition, HAN-based propellants can address the limitations associated with traditional hydrazine propellants. As a result, they are poised to play a pivotal role in future space exploration and satellite propulsion.

[1]V. Lappas and V. Kostopoulos, Satellites Missions and Technologies for Geosciences, IntechOpen, United Kingdom, 2020.
[2]G.P. Sutton and O. Biblarz, Rocket Propulsion Elements (7th Ed.), John Wiley & Sons Inc., New York, 2001.
[3]A. Mayer and W. Wieling (2018), Green Propulsion Research at TNO the Netherlands, Transactions on Aerospace Research 4(253), 1-24.
[4]M. Negri. (2018), New Technologies for Ammonium Dinitramide Based Monopropellant Thrusters – The Project RHEFORM, Acta Astronautica 143, 105-117.
[5]T. Pultarova (2017), Hydrazine Ban Could Cost Europe’s Space Industry Billions. https://spacenews.com/hydrazine-ban-could-cost-europes-space-industry-billions/, access on May 28, 2023.
[6]H. Uramachi, D. Shiraiwa, T. Takai, N. Tanaka, T. Kaneko and K. Furukawa (2019), Green Propulsion Systems for Satellites - Development of Thrusters and Propulsion Systems using Low-toxicity Propellants, Mitsubishi Heavy Industries Technical Review 56(1), 1-7.
[7]H. Meng, P. Khare, G.A. Risha, R.A. Yetter and V. Yang, Decomposition and Ignition of HAN-based Monopropellant by Electrolysis, AIAA Paper 2009-451, 47thAIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, Orlando, Florida, 5-8 January 2009.
[8]K. Hori, T. Katsumi, S. Sawai, N. Azuma, K. Hatai and J. Nakatsuka (2019), HAN‐Based Green Propellant, SHP163 – Its R&D and Test in Space, Propellants, Explosives, Pyrotechnics 44(9), 1080-1083.
[9]J. Rossmeisla, Z.W. Qub, H. Zhub, G.J. Kroesb and J.K. Nørskov (2007), Electrolysis of water on oxide surfaces, Journal of Electroanalytical Chemistry 607, 83-89.
[10]S. Marini, P. Salvi, P. Nelli, R. Pesenti, M. Villa, M. Berrettoni, G. Zangari and Y. Kiros (2012), Advanced alkaline water electrolysis, Electrochimica Acta 82, 384-391.
[11]F. Sapountzi, J. Gracia, C. Weststrate, H. Fredriksson and J. Niemantsverdriet (2017), Electrocatalysts for the generation of hydrogen, oxygen and synthesis gas, Progress in Energy and Combustion Science 58, 1-35.
[12]E.M. Crisp, Electrocatalytic Decomposition of HAN-Based Ionic Liquid Oxidizers, Master Thesis, The Pennsylvania State University, United States, 2021.
[13]H. Ou-Yang, Synthesis and Atmospheric Electrolytic Decomposition Characteristics of Hydroxylammonia Nitrate Aqueous Solutions, Master Thesis, National Cheng Kung University, Taiwan, 2020.
[14]P. Khare, Decomposition and Ignition of HAN-Based Monopropellants by Electrolysis, Master Thesis, The Pennsylvania State University, U.S.A., 2009.
[15]S. Hong, S. Heo, W. Kim, Y.M. Jo, Y.K. Park & J.K. Jeon (2019), Catalytic decomposition of an energetic ionic liquid solution over hexaaluminate catalysts, Catalysts 9, 80.
[16]S. Hoyani, R. Patel, C. Oommen and R. Rajeev (2017), Thermal stability of hydroxylammonium nitrate (HAN), Journal of Thermal Analysis and Calorimetry 129, 1083-1093.
[17]D. Sun, Q. Dai, W.s. Chai, W. Fang and H. Meng (2022), Experimental Studies on Parametric Effects and Reaction Mechanisms in Electrolytic Decomposition and Ignition of HAN Solutions, ACS Omega 7, 18521-18530.
[18]Y.T. Chou, Electrolytic Decomposition Characteristics of Hydroxylammonium Nitrate Based Propellant, Master Thesis, National Cheng Kung University, Taiwan, 2022.
[19]W.S. Chai, K.H. Cheah, K.S. Koh, J. Chin and T.F.W.K. Chik (2016), Parametric Studies of Electrolytic Decomposition of Hydroxylammonium Nitrate (HAN) Energetic Ionic Liquid in Microreactor Using Image Processing Technique, Chemical Engineering Journal 296, 19-27.
[20]K.S. Koh, J. Chin and T.F.W.K. Chik (2013), Role of Electrodes in Ambient Electrolytic Decomposition of Hydroxylammonium Nitrate (HAN) Solutions, Propulsion and Power Research 2(3), 194-200.
[21]R. Yetter, V. Yang, I. Aksay and F. Dryer (2005), Meso and micro scale propulsion concepts for small spacecraft, Air Force Office of Scientific Research, AFRL-SR-AR-TR-05-0014.
[22]M.H. Wu, R. Yetter (2009), A novel electrolytic ignition monopropellant microthruster based on low temperature co-fired ceramic tape technology, Lab on a Chip 9, 910−916.
[23]P. Khare, V. Yang, H. Meng, G.A. Risha and R.A. Yetter (2015), Thermal and Electrolytic Decomposition and Ignition of HAN–Water Solutions, Combustion Science and Technology 187, 1065-1078.
[24]W.S. Chai, K.H. Cheah, K.S. Koh, J. Chin and T.F.W.K. Chik (2016), Parametric Studies of Electrolytic Decomposition of Hydroxylammonium Nitrate (HAN) Energetic Ionic Liquid in Microreactor Using Image Processing Technique, Chemical Engineering Journal 296, 19-27.
[25]E.M. Crisp, Electrocatalytic Decomposition of HAN-Based Ionic Liquid Oxidizers, Master Thesis, The Pennsylvania State University, U.S.A., 2021.
[26]H. Meng, P. Khare, G. Risha, R. Yetter and V. Yang, Decomposition and ignition of HAN-based monopropellants by electrolysis, AIAA Paper2009-451, 47th AIAA Aerospace Science Meeting and Exhibit, Orlando, Florida, January, 2009.
[27]J.C. Oxleya and K.R. Brower, Thermal decomposition of hydroxylamine nitrate, Proceedings of the SPIE 872, 63-70, May 1988, doi: 10.1117/12.943754.
[28]H. Lee, T.A. Litzinger (2001), Thermal decomposition of HAN-based liquid propellant, Combustion and Flame 127(4), 2205-2222.
[29]E.J. Wucherer, T. Cook, M. Stiefel, R. Humphries and J. Parker, Hydrazine catalyst production sustaining S-405 technology, AIAA Paper 2003-5079, 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Huntsville, Alabama, 20-23 July 2003.
[30]E. Schmidt, Hydrazine and its Derivatives, Preparation, Properties, Applications, Wiley, New York, 1984.
[31]R. Amrousse, T. Katsumi, Y. Niboshi, N. Azuma, A. Bachar and K. Hori (2013), Performance and deactivation of Ir-based catalyst during hydroxylamminium nitrate catalytic decomposition, Applied Catalysis A: General 452, 64-68.
[32]R. Amrousse, T. Katsumi, A. Bachar, R. Brahmi, M. Bensitel & K. Hori, Chemical engineering study for hydroxylammonium nitrate monopropellant decomposition over monolith and grain metal-based catalysts, Reaction Kinetics, Mechanisms and Catalysis. 111, 71–88, 2014.
[33]R. Amrousse, T. Katsumi, N. Itouyama, N. Azuma, H. Kagawa, K. Hatai, H. Ikeda & K. Hori (2015), New HAN-based mixtures for reaction control system and low toxic spacecraft propulsion subsystem, Thermal decomposition and possible thruster applications, Combustion and Flame 162, 2686-2692.
[34]R. Agnihotri and C. Oommen (2018), Cerium oxide based active catalyst for hydroxylammonium nitrate (HAN) fueled monopropellant thrusters, RSC Adv. 8, 22293-22302.
[35]R. Agnihotri and C. Oommen (2020), Evaluation of hydroxylammonium nitrate (HAN) decomposition using bifunctional catalyst for thruster application, Molecular Catalysis 486, 110851.
[36]M. Tian, X. D. Wang & T. Zhang (2016), Hexaaluminates: a review of the structure, synthesis and catalytic performance, Catalysis Science & Technology 6, 1984-2004.
[37]R. Agnihotri and C. Oommen (2020), Evaluation of hydroxylammonium nitrate (HAN) decomposition using bifunctional catalyst for thruster application, Molecular Catalysis 486, 110851.
[38]R. Agnihotri and C. Oommen (2021), Kinetics and mechanism of thermal and catalytic decomposition of hydroxylammonium nitrate (HAN) monopropellant, Propellants, Explosives, Pyrotechnics 46, 286-298.
[39]S. Lee, S. Kang, S. Kwon and G. Park (2016), Lanthanum hexaaluminate catalyst support in a hydrogen peroxide thruster, Journal of Propulsion and Power 32(5), 1301-1304.
[40]S. Hong, S. Heo, W. Kim, Y.M. Jo, Y.K. Park and J.K. Jeon (2019), Catalytic decomposition of an energetic ionic liquid solution over hexaaluminate catalysts, Catalysts 9, 80.
[41]J.J. Torrez-Herrera, S.A. Korili & A. Gil (2020), Progress in the synthesis and applications of hexaaluminate-based catalysts, Catalysis Reviews 64(3), 592-630.
[42]K.I. Lao, Catalytic Decomposition of HAN-Based Monopropellants with Hexaaluminates, Master Thesis, National Cheng Kung University, Taiwan, 2022.
[43]Y.A. Chana, Development of a HTP Mono-propellant Thruster by Using Composite Silver Catalyst, Master Thesis, National Cheng Kung University, Taiwan, 2011.
[44]L. Courthéoux, R. Eloirdi, S. Rossignol, C. Kappenstein and D. Duprez, Catalytic decomposition of HAN-water binary mixtures, 38th AIAA/ASME /SAE/ASEE Joint propulsion conference and exhibit, Indianapolis, United States, Jul 2002.
[45]R. Sasse (1998), Thermal Characteristics of Concentrated Hydroxylammonium Nitrate Solutions, BRL-MR-3651.
[46]R. Sasse (1990), Analysis of Hydroxylammonium Nitrate Based Liquid Propellants, BRL-TR-3154.
[47]T. Katsumi, H. Kodama, T. Matsuo, H. Ogawa, N. Tsuboi and K. Hori (2009), Combustion Characteristics of a Hydroxylammonium Nitrate Based Liquid Propellant. Combustion Mechanism and Application to Thrusters, Combustion, Explosion and Shock Waves 45(4), 442-453.
[48]S. Hoyani, R. Patel, C. Oommen and R. Rajeev (2017), Thermal stability of hydroxylammonium nitrate (HAN), Journal of Thermal Analysis and Calorimetry 129, 1083-1093.
[49]N. Klein, Ignition and combustion of the HAN-based liquid propellants, the 27th JANNAF Combustion Subcommittee Meeting, Cheyenne, WY, Nov 1990. CPIA Pub. 557, Vol. 1, pp. 443-450.
[50]I.Y. Tsai, Reaction Characteristics of Hydroxylammonium Nitrate Based Propellants and the Development of Prototype Microthrusters, Master Thesis, National Cheng Kung University, Taiwan, 2023.