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Biswas S, Antonov I, Fujioka K, Rizzo GL, Chambreau SD, Schneider S, Sun R, Kaiser RI. Unraveling the initial steps of the ignition chemistry of the hypergolic ionic liquid 1-ethyl-3-methylimidazolium cyanoborohydride ([EMIM][CBH]) with nitric acid (HNO 3) exploiting chirped pulse triggered droplet merging. Phys Chem Chem Phys 2023; 25:6602-6625. [PMID: 36806836 DOI: 10.1039/d2cp05943f] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
The composition of the products and the mechanistic routes for the reaction of the hypergolic ionic liquid (HIL) 1-ethyl-3-methylimidazolium cyanoborohydride ([EMIM][CBH]) and nitric acid (HNO3) at various concentrations from 10% to 70% were explored using a contactless single droplet merging within an ultrasonic levitation setup in an inert atmosphere of argon to reveal the initial steps that cause hypergolicity. The reactions were initiated through controlled droplet-merging manipulation triggered by a frequency chirp pulse amplitude modulation. Utilizing the high-speed optical and infrared cameras surrounding the levitation process chamber, intriguing visual images were unveiled: (i) extensive gas release and (ii) temperature rises of up to 435 K in the merged droplets. The gas development was validated qualitatively and quantitatively with Fourier Transform Infrared Spectroscopy (FTIR) indicating the major gas-phase products to be hydrogen cyanide (HCN) and nitrous oxide (N2O). The merged droplet was also probed by pulsed Raman spectroscopy which deciphered features for key functional groups of the reaction products and intermediates (-BH, -BH2, -BH3, -NCO); reaction kinetics revealed that the reaction was initiated by the interaction of the [CBH]- anion of the HIL with the oxidizer (HNO3) through proton transfer. Computations indicate the formation of a van-der-Waals complex between the [CBH]- anion and HNO3 initially, followed by proton transfer from the acid to the anion and subsequent extensive isomerization; these rearrangements were found to be essential for the formation of HCN and N2O. The exoergicity observed during the merging process provides a molar enthalpy change up to 10 kJ mol-1 to the system, which could be sufficient for a significant fraction of the reactants of about 11% to overcome the reaction barriers in the individual steps of the computationally determined minimum energy pathways.
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Affiliation(s)
- Souvick Biswas
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Ivan Antonov
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Kazuumi Fujioka
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Grace L Rizzo
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | | | - Stefan Schneider
- Air Force Research Laboratory, Edwards Air Force Base, California 93524, USA
| | - Rui Sun
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
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2
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Fujioka K, Kaiser RI, Sun R. Unsupervised Reaction Pathways Search for the Oxidation of Hypergolic Ionic Liquids: 1-Ethyl-3-methylimidazolium Cyanoborohydride (EMIM +/CBH -) as a Case Study. J Phys Chem A 2023; 127:913-923. [PMID: 36574603 DOI: 10.1021/acs.jpca.2c07624] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Hypergolic ionic liquids have come under increased study for having several desirable properties as a fuel source. One particular ionic liquid, 1-ethyl-3-methylimidazolium/cyanoborohydride (EMIM+/CBH-), and oxidant, nitric acid (HNO3), has been reported to be hypergolic experimentally, but its mechanism is not well-understood at a mechanistic level. In this computational study, the reaction is first probed with ab initio molecular dynamics simulations to confirm that anion-oxidant interactions likely are the first step in the mechanism. Second, the potential energy surface of the anion-oxidant system is studied with an in-depth search over possible isomerizations, and a network of possible intermediates are found. The critical point search is unsupervised and thus has the potential of identifying structures that deviate from chemical intuition. Molecular graphs are employed for analyzing 3000+ intermediates found, and nudged elastic band calculations are employed to identify transition states between them. Finally, the reactivity of the system is discussed through examination of minimal energy paths connecting the reactant to various common products from hypergolic ionic liquid oxidation. Eight products are reported for this system: NO, N2O, NO2, HNO, HONO, HNO2, HCN, and H2O. All reaction paths leading to these exothermic products have overall reaction barriers of 6-7 kcal/mol.
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Affiliation(s)
- Kazuumi Fujioka
- Department of Chemistry, The University of Hawai'i at Manoa, Honolulu, Hawaii96822, United States
| | - Ralf I Kaiser
- Department of Chemistry, The University of Hawai'i at Manoa, Honolulu, Hawaii96822, United States
| | - Rui Sun
- Department of Chemistry, The University of Hawai'i at Manoa, Honolulu, Hawaii96822, United States
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3
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Xie HH, Wang Q, Weng JL, Yan YF, Bian HY, Huang Y, Zheng FK, Qiu RH, Xu JG. Coordination polymerization of nitrogen-rich linkers and dicyanamide anions toward energetic coordination polymers with low sensitivities. Dalton Trans 2023; 52:818-824. [PMID: 36594594 DOI: 10.1039/d2dt03180a] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The design and synthesis of energetic materials (EMs) with high energy and reliable stabilities has attracted much attention in the field of EMs. In this work, we employed a strategy of the coordination polymerization of mild dicyanamide ions (DCA-), two isomeric ligands 1-methyl-5-aminotetrazole (1-MAT) and 2-methyl-5-aminotetrazole (2-MAT) to construct energetic coordination polymers (ECPs). Four new ECPs {[Co(DCA)2(1-MAT)2]·H2O}n1, [Cu(DCA)2(1-MAT)]n2, [Cd(DCA)2(1-MAT)2]n3 and [Cd(DCA)2(2-MAT)2]n4 were successfully synthesized through solvent evaporation routes. Compounds 1 and 4 display 1D chains, while 2 and 3 exhibit 2D-layered structures. Compounds 1-3 with the 1-MAT ligand all exhibit reliable thermal stabilities (> 200 °C). The calculated heats of detonation (ΔHdet) of 1-3 are all higher than 1.4 kJ g-1, which are higher than traditional explosive TNT (1.22 kJ g-1) and the reported ECP AgMtta (HMtta = 5-methyl-1H-tetrazole, ΔHdet = 1.32 kJ g-1). Furthermore, sensitivity testing demonstrates that 1-4 features low mechanical sensitivity to external mechanical action in contrast with the extremely sensitive azide-based ECPs [Cu3(2-MAT)2(N3)6]n. In addition, compound 2 shows hypergolic properties via an 'oxidizer-fuel' drop experiment, demonstrating its application prospects in the field of propellants. This work details an approach of synthesizing multipurpose ECPs with reliable stabilities by introducing mild dicyanamide anions into nitrogen-rich skeletons.
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Affiliation(s)
- Hao-Hui Xie
- College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350108, China.
| | - Qin Wang
- College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350108, China.
| | - Jiao-Lin Weng
- College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350108, China.
| | - Yun-Fan Yan
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
| | - Hong-Yi Bian
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
| | - Ying Huang
- College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350108, China.
| | - Fa-Kun Zheng
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China.,Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian 350108, PR China
| | - Ren-Hui Qiu
- College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350108, China.
| | - Jian-Gang Xu
- College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350108, China. .,State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China.,Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian 350108, PR China
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4
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Zhang Z, Li B, Chen Q, Chen X, Yan T, Zheng W, Zuo C. Catalytic decomposition of hydroxylamine nitrate and hydrazine nitrate using Ru/ZSM-5 catalyst under mild reaction conditions. RSC Adv 2022; 12:4469-4474. [PMID: 35425524 PMCID: PMC8981218 DOI: 10.1039/d1ra07724d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 12/20/2021] [Indexed: 12/18/2022] Open
Abstract
Hydroxylamine nitrate and hydrazine nitrate are dangerous explosives and toxic chemicals. Catalytic decomposition is an efficient way for disposal of these chemicals. In the current work, a Ru/ZSM-5 catalyst has been fabricated and evaluated for the decomposition of hydroxylamine nitrate and hydrazine nitrate in 1.0 mol L−1 HNO3. The hydroxylamine nitrate and hydrazine nitrate can be thoroughly decomposed under 80 °C. And the Ru/ZSM-5 catalyst can be separated from the reaction mixture and reused at least 130 times with stable catalytic performance. Easy operation, less solid waste generation, and a simple catalytic device make the strategy reported here practical, environmentally friendly, and economically attractive. The Ru/ZSM-5 catalyst was shown to be an efficient heterogeneous catalyst for decomposition of hydroxylamine nitrate and hydrazine nitrate. The catalyst could be recovered by filtration and reused, showing good potential for industrial application.![]()
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Affiliation(s)
- Zhipeng Zhang
- Chinese Institute of Atomic Energy PO Box 275(126) Beijing 102413 China
| | - Baole Li
- Chinese Institute of Atomic Energy PO Box 275(126) Beijing 102413 China
| | - Qi Chen
- Chinese Institute of Atomic Energy PO Box 275(126) Beijing 102413 China
| | - Xiwen Chen
- Chinese Institute of Atomic Energy PO Box 275(126) Beijing 102413 China
| | - Taihong Yan
- Chinese Institute of Atomic Energy PO Box 275(126) Beijing 102413 China
| | - Weifang Zheng
- Chinese Institute of Atomic Energy PO Box 275(126) Beijing 102413 China
| | - Chen Zuo
- Chinese Institute of Atomic Energy PO Box 275(126) Beijing 102413 China
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5
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Chambreau SD, Popolan-Vaida DM, Kostko O, Lee JK, Zhou Z, Brown TA, Jones P, Shao K, Zhang J, Vaghjiani GL, Zare RN, Leone SR. Thermal and Catalytic Decomposition of 2-Hydroxyethylhydrazine and 2-Hydroxyethylhydrazinium Nitrate Ionic Liquid. J Phys Chem A 2022; 126:373-394. [PMID: 35014846 DOI: 10.1021/acs.jpca.1c07408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
To develop chemical kinetics models for the combustion of ionic liquid-based monopropellants, identification of the elementary steps in the thermal and catalytic decomposition of components such as 2-hydroxyethylhydrazinium nitrate (HEHN) is needed but is currently not well understood. The first decomposition step in protic ionic liquids such as HEHN is typically the proton transfer from the cation to the anion, resulting in the formation of 2-hydroxyethylhydrazine (HEH) and HNO3. In the first part of this investigation, the high-temperature thermal decomposition of HEH is probed with flash pyrolysis (<1400 K) and vacuum ultraviolet (10.45 eV) photoionization time-of-flight mass spectrometry (VUV-PI-TOFMS). Next, the investigation into the thermal and catalytic decomposition of HEHN includes two mass spectrometric techniques: (1) tunable VUV-PI-TOFMS (7.4-15 eV) and (2) ambient ionization mass spectrometry utilizing both plasma and laser ionization techniques whereby HEHN is introduced onto a heated inert or iridium catalytic surface and the products are probed. The products can be identified by their masses, their ionization energies, and their collision-induced fragmentation patterns. Formation of product species indicates that catalytic surface recombination is an important reaction process in the decomposition mechanism of HEHN. The products and their possible elementary reaction mechanisms are discussed.
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Affiliation(s)
- Steven D Chambreau
- Jacobs Technology, Inc., Edwards Air Force Base, California 93524, United States
| | - Denisia M Popolan-Vaida
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.,Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States.,Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Oleg Kostko
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jae Kyoo Lee
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Zhenpeng Zhou
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Timothy A Brown
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Paul Jones
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Kuanliang Shao
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Jingsong Zhang
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Ghanshyam L Vaghjiani
- In-Space Propulsion Branch, Rocket Propulsion Division, Aerospace Systems Directorate, Air Force Research Laboratory, AFRL/RQRS, Edwards Air Force Base, California 93524, United States
| | - Richard N Zare
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Stephen R Leone
- Departments of Chemistry and Physics, University of California, Berkeley, California 94720, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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6
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Zhou W, Liu J, Chambreau SD, Vaghjiani GL. Molecular Dynamics Simulations, Reaction Pathway and Mechanism Dissection, and Kinetics Modeling of the Nitric Acid Oxidation of Dicyanamide and Dicyanoborohydride Anions. J Phys Chem B 2020; 124:11175-11188. [PMID: 33210915 DOI: 10.1021/acs.jpcb.0c07823] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Direct dynamics simulations of HNO3 with dicyanamide anion DCA- (i.e., N(CN)2-) and dicyanoborohydride anion DCBH- (i.e., BH2(CN)2-) were performed at the B3LYP/6-31+G(d) level of theory in an attempt to elucidate the primary and secondary reactions in the two reaction systems. Guided by trajectory results, reaction coordinates and potential energy diagrams were mapped out for the oxidation of DCA- and DCBH- by one and two HNO3 molecules, respectively, in the gas-phase and in the condensed-phase ionic liquids using the B3LYP/6-311++G(d,p) method. The oxidation of DCA- by HNO3 is initiated by proton transfer. The most important pathway leads to the formation of O2N-NHC(O)NCN-, and the latter reacts with a second HNO3 to produce O2N-NHC(O)NC(O)NH-NO2-(DNB-). The oxidation of DCBH- by HNO3 may follow a similar mechanism as that of DCA-, producing two analogue products: O2N-NHC(O)BH2CN- and O2N-NHC(O)BH2C(O)NH-NO2-. Moreover, two new, unique reaction pathways were discovered for DCBH- because of its boron-hydride group: (1) isomerization of DCBH- to CNBH2CN- and CNBH2NC- and (2) H2 elimination in which the proton in HNO3 combines with a hydride-H in DCBH-. The Rice-Ramsperger-Kassel-Marcus (RRKM) theory was utilized to calculate reaction kinetics and product branching ratios. The RRKM results indicate that the formation of DNB- is exclusively important in the oxidation of DCA-, whereas the same type of reaction is a minor channel in the oxidation of DCBH-. In the latter case, H2 elimination becomes dominating. The RRKM modeling also indicates that the oxidation rate constant of DCBH- is higher than that of DCA- by an order of magnitude. This rationalizes the enhanced preignition performance of DCBH- over DCA- with HNO3.
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Affiliation(s)
- Wenjing Zhou
- Department of Chemistry and Biochemistry, Queens College and the Graduate Center of the City University of New York, 65-30 Kissena Blvd., Queens, New York 11367, United States
| | - Jianbo Liu
- Department of Chemistry and Biochemistry, Queens College and the Graduate Center of the City University of New York, 65-30 Kissena Blvd., Queens, New York 11367, United States
| | - Steven D Chambreau
- Jacobs, Inc., Air Force Research Laboratory, Edwards AFB, California 93524, United States
| | - Ghanshyam L Vaghjiani
- In-Space Propulsion Branch, Rocket Propulsion Division, Aerospace Systems Directorate, Air Force Research Laboratory, AFRL/RQRS, Edwards AFB, California 93524, United States
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7
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Brotton SJ, Kaiser RI. Controlled Chemistry via Contactless Manipulation and Merging of Droplets in an Acoustic Levitator. Anal Chem 2020; 92:8371-8377. [PMID: 32476411 DOI: 10.1021/acs.analchem.0c00929] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A unique, versatile, and material-independent approach to manipulate contactlessly and merge two chemically distinct droplets suspended in an acoustic levitator is reported. Large-amplitude axial oscillations are induced in the top droplet by low-frequency amplitude modulation of the ultrasonic carrier wave, which causes the top sample to merge with the sample in the pressure minimum below. The levitator is enclosed within a pressure-compatible process chamber to enable control of the environmental conditions. The merging technique permits precise control of the substances affecting the chemical reactions, the sample temperature, the volumes of the liquid reactants down to the picoliter range, and the mixing locations in space and time. The performance of this approach is demonstrated by merging droplets of water (H2O) and ethanol (C2H5OH), conducting an acid-base reaction between aqueous droplets of sodium hydroxycarbonate (NaHCO3) and acetic acid (CH3COOH), the hypergolic explosion produced via merging a droplet of an ionic liquid with nitric acid (HNO3), and the coalescence of a solid particle (CuSO4·5H2O) and a water droplet followed by dehydration using a carbon dioxide laser. The physical and chemical changes produced by the merging are traced in real time via complementary Raman, Fourier-transform infrared, and ultraviolet-visible spectroscopies. The concept of the contactless manipulation of liquid droplets and solid particles may fundamentally change how scientists control and study chemical reactions relevant to, for example, combustion systems, material sciences, medicinal chemistry, planetary sciences, and biochemistry.
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Affiliation(s)
- Stephen J Brotton
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
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8
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Liu J, Zhou W, Chambreau SD, Vaghjiani GL. Molecular Dynamics Simulations and Product Vibrational Spectral Analysis for the Reactions of NO 2 with 1-Ethyl-3-methylimidazolium Dicyanamide (EMIM +DCA -), 1-Butyl-3-methylimidazolium Dicyanamide (BMIM +DCA -), and 1-Allyl-3-methylimidazolium Dicyanamide (AMIM +DCA -). J Phys Chem B 2020; 124:4303-4325. [PMID: 32364732 DOI: 10.1021/acs.jpcb.0c02253] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Direct dynamics trajectory simulations were carried out for the NO2 oxidation of 1-ethyl-3-methylimidazolium dicyanamide (EMIM+DCA-), which were aimed at probing the nature of the primary and secondary reactions in the system. Guided by trajectory results, reaction coordinates and potential energy diagrams were mapped out for NO2 with EMIM+DCA-, as well as with its analogues 1-butyl-3-methylimidazolium dicyanamide (BMIM+DCA-) and 1-allyl-3-methylimidazolium dicyanamide (AMIM+DCA-). Reactions of the dialkylimidazolium-dicyanamide (DCA) ionic liquids (ILs) are all initiated by proton transfer and/or alkyl abstraction between 1,3-dialkylimidazolium cations and DCA- anion, of which two exoergic pathways are particularly relevant to their oxidation activities. One pathway is the transfer of a Hβ-proton from the ethyl, butyl, or allyl group of the dialkylimidazolium cation to DCA- that results in the concomitant elimination of the corresponding alkyl as a neutral alkene, and the other pathway is the alkyl abstraction by DCA- via a second order nucleophilic substitution (SN2) mechanism. The intra-ion-pair reaction products, including [dialkylimidazolium+ - HC2+], alkylimidazole, alkene, alkyl-DCA, HDCA, and DCA-, react with NO2 and favor the formation of nitrite (-ONO) complexes over nitro (-NO2) complexes, albeit the two complex structures have similar formation energies. The exoergic intra-ion-pair reactions in the dialkylimidazolium-DCA ILs account for their significantly higher oxidation activities over the previously reported 1-methyl-4-amino-1,2,4-triazolium dicyanamide [Liu, J.; J. Phys. Chem. B 2019, 123, 2956-2970] and for the relatively higher reactivity of BMIM+DCA- vs AMIM+DCA- as BMIM+ has a higher reaction path degeneracy for intra-ion-pair Hβ-proton transfer and its Hβ-transfer is more energetically favorable. To validate and directly compare our computational results with spectral measurements in the ILs, infrared and Raman spectra of BMIM+DCA- and AMIM+DCA- and their products with NO2 were calculated using an ionic liquid solvation model. The simulated spectra reproduced all of the vibrational frequencies detected in the reactions of BMIM+DCA- and AMIM+DCA- IL droplets with NO2 (as reported by Brotton et al. [ J. Phys. Chem. A 2018, 122, 7351-7377] and Lucas et al. [ J. Phys. Chem. A 2019, 123, 400-416]).
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Affiliation(s)
- Jianbo Liu
- Department of Chemistry and Biochemistry, Queens College and the Graduate Center of the City University of New York, 65-30 Kissena Boulevard, Queens, New York 11367, United States
| | - Wenjing Zhou
- Department of Chemistry and Biochemistry, Queens College and the Graduate Center of the City University of New York, 65-30 Kissena Boulevard, Queens, New York 11367, United States
| | - Steven D Chambreau
- ERC, Inc., Air Force Research Laboratory, Edwards Air Force Base, California 93524, United States
| | - Ghanshyam L Vaghjiani
- In-Space Propulsion Branch, Rocket Propulsion Division, Aerospace Systems Directorate, Air Force Research Laboratory, AFRL/RQRS, Edwards Air Force Base, California 93524, United States
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9
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Thomas AE, Chambreau SD, Redeker ND, Esparza AA, Shafirovich E, Ribbeck T, Sprenger JAP, Finze M, Vaghjiani GL. Thermal Decomposition and Hypergolic Reaction of a Dicyanoborohydride Ionic Liquid. J Phys Chem A 2020; 124:864-874. [PMID: 31914728 DOI: 10.1021/acs.jpca.9b09242] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this study, in situ infrared spectroscopy techniques and thermogravimetric analysis coupled with mass spectrometry (TGA-MS) are employed to characterize the reactivity of the ionic liquid, 1-butyl-3-methylimidazolium dicyanoborohydride (BMIM+DCBH-), in comparison to the well-characterized 1-butyl-3-methylimidazolium dicyanamide (BMIM+DCA-) ionic liquid. TGA measurements determined the enthalpy of vaporization (ΔHvap) to be 112.7 ± 12.3 kJ/mol at 298 K. A rapid scan Fourier transform infrared spectrometer was used to obtain vibrational information useful in tracking the appearance and disappearance of species in the hypergolic reactions of BMIM+DCBH- and BMIM+DCA- with white fuming nitric acid (WFNA) and in the thermal decomposition of these energetic ionic liquids. Attenuated total reflectance measurements recorded the infrared spectra of the reactant sample (BMIM+DCBH-) and the liquid reaction products after reacting with WFNA. Computational chemistry efforts, aided by the experimental results, were used to propose key reaction pathways leading to the hypergolic ignition of BMIM+DCBH- + WFNA. Experimental results indicate that the hypergolic reaction of BMIM+DCBH- with WFNA generates both common and unique intermediates as compared to previous BMIM+DCA- + WFNA investigations: nitrous oxide was generated during both hypergolic reactions indicating that it may play a crucial role in the hypergolic ignition process, NO2 was generated in significantly higher concentrations for BMIM+DCBH- than for BMIM+DCA-, CO2 was only generated for BMIM+DCA-, and HCN was only generated during thermal decomposition and hypergolic ignition of BMIM+DCBH-.
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Affiliation(s)
- Anna E Thomas
- Department of Aeronautics and Astronautics , Stanford University , Stanford , California 94305 , United States
| | - Steven D Chambreau
- ERC Inc. , Air Force Research Laboratory, AFRL/RQRP , Edwards Air Force Base , California 93524 , United States
| | - Neil D Redeker
- ERC Inc. , Air Force Research Laboratory, AFRL/RQRP , Edwards Air Force Base , California 93524 , United States
| | - Alan A Esparza
- Department of Mechanical Engineering , The University of Texas at El Paso , 500 W. University Avenue, El Paso , Texas 79968 , United States
| | - Evgeny Shafirovich
- Department of Mechanical Engineering , The University of Texas at El Paso , 500 W. University Avenue, El Paso , Texas 79968 , United States
| | - Tatjana Ribbeck
- Institut für Anorganische Chemie, Institut für nachhaltige Chemie & Katalyse mit Bor (ICB) , Julius-Maximilians-Universität Würzburg , Am Hubland, 97074 Würzburg , Germany
| | - Jan A P Sprenger
- Institut für Anorganische Chemie, Institut für nachhaltige Chemie & Katalyse mit Bor (ICB) , Julius-Maximilians-Universität Würzburg , Am Hubland, 97074 Würzburg , Germany
| | - Maik Finze
- Institut für Anorganische Chemie, Institut für nachhaltige Chemie & Katalyse mit Bor (ICB) , Julius-Maximilians-Universität Würzburg , Am Hubland, 97074 Würzburg , Germany
| | - Ghanshyam L Vaghjiani
- Aerospace Systems Directorate , Air Force Research Laboratory , AFRL/RQRS, Edwards Air Force Base , California 93524 , United States
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10
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Han Y, Hobbie EK, Kilin DS. First-Principles Molecular Dynamics of Monomethylhydrazine and Nitrogen Dioxide. J Phys Chem Lett 2019; 10:2394-2399. [PMID: 30978025 DOI: 10.1021/acs.jpclett.9b00674] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The exploration of chemical reactions preceding ignition is essential for the development of ideal hypergolic propellants. Unexpected reaction pathways of a hypergolic mixture composed of monomethylhydrazine and nitrogen dioxide are predicted through a cooperative combination of (i) spin-unrestricted ab initio molecular dynamics (AIMD) and (ii) wave packet dynamics of protons. Ensembles of AIMD trajectories reveal a sequence of reaction steps for proton transfer and rupture of the C-N bond. The details of proton transfer are explored by wave packet dynamics on the basis of ab initio potential energy surfaces from AIMD trajectories. The possibility of spontaneous ignition of this hypergolic mixture at room temperature is predicted as a quantized feature of proton-transfer dynamics.
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Affiliation(s)
- Yulun Han
- Department of Chemistry and Biochemistry , North Dakota State University , Fargo , North Dakota 58102 , United States
| | - Erik K Hobbie
- Department of Physics , North Dakota State University , Fargo , North Dakota 58102 , United States
| | - Dmitri S Kilin
- Department of Chemistry and Biochemistry , North Dakota State University , Fargo , North Dakota 58102 , United States
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11
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Liu J, Zhou W, Chambreau SD, Vaghjiani GL. Computational Study of the Reaction of 1-Methyl-4-amino-1,2,4-triazolium Dicyanamide with NO 2: From Reaction Dynamics to Potential Surfaces, Kinetics and Spectroscopy. J Phys Chem B 2019; 123:2956-2970. [PMID: 30789734 DOI: 10.1021/acs.jpcb.9b01015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Direct dynamics trajectories were calculated at the B3LYP/6-31G(d) level of theory in an attempt to understand the reaction of 1-methyl-4-amino-1,2,4-triazolium dicyanamide (MAT+DCA-) with NO2. The trajectories revealed an extensive intra-ion-pair proton transfer in MAT+DCA-. The reaction pathways of the ensuing HDCA (i.e., HNCNCN) and [MAT+ - HC5+] (i.e., deprotonated at C5-H of MAT+) molecules as well as DCA- with NO2 were identified. The reaction of NO2 with HDCA and DCA- produces HNC(-ONO)NCN and NCNC(-ONO)N- or NCNCN-NO2-, respectively, whereas that with [MAT+ - HC5+] results in the formation of 5-O-MAT (i.e., 4-amino-2-methyl-2,4-dihydro-3 H-1,2,4-triazo-3-one) + NO and [MAT+ - H2+] + HNO2. Using trajectories for guidance, structures of intermediates, transition states and products, and the corresponding reaction potential surfaces were elucidated at B3LYP/6-311++ G(d,p). Rice-Ramsperger-Kassel-Marcus (RRKM) theory was utilized to calculate the reaction rates and statistical product branching ratios. A comparison of direct dynamics simulations with RRKM modeling results indicate that the reactions of NO2 with HDCA and DCA- are nonstatistical. To validate our computational results, infrared and Raman spectra of MAT+DCA- and its reaction products with NO2 were calculated using an ionic liquid solvation model. The calculated spectra reproduced the vibrational frequencies detected in an earlier spectroscopic study of MAT+DCA- droplets with NO2 [ Brotton , S. J. ; J. Phys. Chem. Lett. 2017 , 8 , 6053 ].
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Affiliation(s)
- Jianbo Liu
- Department of Chemistry and Biochemistry , Queens College and the Graduate Center of the City University of New York , 65-30 Kissena Boulevard , Queens , New York 11367 , United States
| | - Wenjing Zhou
- Department of Chemistry and Biochemistry , Queens College and the Graduate Center of the City University of New York , 65-30 Kissena Boulevard , Queens , New York 11367 , United States
| | - Steven D Chambreau
- ERC, Inc. , Air Force Research Laboratory , Edwards Air Force Base , California 93524 , United States
| | - Ghanshyam L Vaghjiani
- In-Space Propulsion Branch, Rocket Propulsion Division, Aerospace Systems Directorate , Air Force Research Laboratory, AFRL/RQRS , Edwards Air Force Base , California 93524 , United States
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12
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Brotton SJ, Kaiser RI. Spectroscopic Study on the Polymer Condensates Formed via Pyrolysis of Levitated Droplets of Dicyanamide-Containing Ionic Liquids. J Phys Chem A 2019; 123:1153-1167. [DOI: 10.1021/acs.jpca.8b08993] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Stephen J. Brotton
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
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13
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Lucas M, Brotton SJ, Shukla SK, Yu J, Anderson SL, Kaiser RI. Oxidation of a Levitated Droplet of 1-Allyl-3-methylimidazolium Dicyanamide by Nitrogen Dioxide. J Phys Chem A 2019; 123:400-416. [PMID: 30336051 DOI: 10.1021/acs.jpca.8b08395] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Understanding the reaction mechanisms of ionic liquids and their oxidizers is necessary to develop the next generation of hypergolic, ionic-liquid-based fuels. We studied reactions between a levitated droplet of 1-allyl-3-methylimidazolium dicyanamide ([AMIM][DCA]), with and without hydrogen-capped boron nanoparticles, and nitrogen dioxide (NO2). The reactions were monitored with Fourier-transform infrared (FTIR) and Raman spectroscopy. The emergence of new structures in the FTIR and Raman spectra is consistent with the formation of functional groups including organic nitrites (RONO), nitroamines (R1R2NNO2), and carbonitrates (R1R2C=NO2-). Possible reaction mechanisms based on these new functional groups are discussed. The reaction rates were deduced at various temperatures by heating the levitated droplets with a carbon dioxide laser. We thereby determined an overall activation energy of 38.5 ± 2.3 kJ mol-1 for the oxidation of [AMIM][DCA] for the first time.
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Affiliation(s)
- Michael Lucas
- Department of Chemistry , University of Hawaii at Manoa , Honolulu , Hawaii 96822 , United States
| | - Stephen J Brotton
- Department of Chemistry , University of Hawaii at Manoa , Honolulu , Hawaii 96822 , United States
| | - Shashi Kant Shukla
- Department of Chemistry , University of Hawaii at Manoa , Honolulu , Hawaii 96822 , United States
| | - Jiang Yu
- Department of Chemistry , University of Utah , Salt Lake City , Utah 84112 , United States
| | - Scott L Anderson
- Department of Chemistry , University of Utah , Salt Lake City , Utah 84112 , United States
| | - Ralf I Kaiser
- Department of Chemistry , University of Hawaii at Manoa , Honolulu , Hawaii 96822 , United States
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14
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Thomas A, Chambreau SD, Vaghjiani GL. Ignition Delay Reduction with Sodium Addition to Imidazolium-Based Dicyanamide Ionic Liquid. J Phys Chem A 2019; 123:10-14. [PMID: 30543100 DOI: 10.1021/acs.jpca.8b08678] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A range of ionic liquids (ILs) have been synthesized and modeled to better understand the role of the cation in the ignition of hypergolic ionic liquids. Vogelhuber et al. have shown by density functional theory methods that the addition of sodium cations to an ionic liquid promotes ignition with white fuming nitric acid (WFNA) by lowering energy barriers. To validate this prediction, solid sodium dicyanamide (Na+DCA-) was added at various weight percents to 1-butyl-3-methylimidazolium dicyanamide (BMIM+DCA-). The ignition delay was measured for each mixture with WFNA. Overall, it was found that the Na+DCA- lowered the ignition delay by 11 ms at 7 wt %. The calculations done by Vogelhuber et al. appear to be consistent with this observation. The sodium cation may play a role by orienting the anion with the WFNA resulting in the favorable reaction energetics observed.
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Affiliation(s)
- Anna Thomas
- Department of Aeronautics and Astronautics , Stanford University , Stanford , California 94305 , United States
| | - Steven D Chambreau
- ERC Inc. , Air Force Research Laboratory, AFRL , Edwards Air Force Base , California 93524 , United States
| | - Ghanshyam L Vaghjiani
- Aerospace Systems Directorate , Air Force Research Laboratory, AFRL/RQRS , Edwards Air Force Base , California 93524 , United States
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15
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Lucas M, Brotton SJ, Sprenger JAP, Finze M, Sharma SK, Kaiser RI. Oxidation of a Levitated 1-Butyl-3-methylimidazolium Dicyanoborate Droplet by Nitrogen Dioxide. J Phys Chem A 2019; 123:780-795. [DOI: 10.1021/acs.jpca.8b11796] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michael Lucas
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Stephen J. Brotton
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Jan A. P. Sprenger
- Institute for Inorganic Chemistry, Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Maik Finze
- Institute for Inorganic Chemistry, Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Shiv K. Sharma
- Hawaii Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
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16
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Brotton SJ, Lucas M, Jensen TN, Anderson SL, Kaiser RI. Spectroscopic Study on the Intermediates and Reaction Rates in the Oxidation of Levitated Droplets of Energetic Ionic Liquids by Nitrogen Dioxide. J Phys Chem A 2018; 122:7351-7377. [DOI: 10.1021/acs.jpca.8b05244] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stephen J. Brotton
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Michael Lucas
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Tonya N. Jensen
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Scott L. Anderson
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
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17
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Vogelhuber KM, Booth RS, Annesley CJ. Theoretical Investigation of the Reactivity of Sodium Dicyanamide with Nitric Acid. J Phys Chem A 2018; 122:1954-1959. [PMID: 29384671 DOI: 10.1021/acs.jpca.7b11661] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
There is a need to replace current hydrazine fuels with safer propellants, and dicyanamide (DCA-)-based systems have emerged as promising alternatives because they autoignite when mixed with some oxidizers. Previous studies of the hypergolic reaction mechanism have focused on the reaction between DCA- and the oxidizer HNO3; here, we compare the calculated pathway of DCA- + HNO3 with the reaction coordinate of the ion pair sodium dicyanamide with nitric acid, Na[DCA] + HNO3. Enthalpies and free energies are calculated in the gas phase and in solution using a quantum mechanical continuum solvation model, SMD-GIL. The barriers to the Na[DCA] + HNO3 reaction are dramatically lowered relative to those of the reaction with the bare anion, and an exothermic exit channel to produce NaNO3 and the reactive intermediate HDCA appears. These results suggest that Na[DCA] may accelerate the ignition reaction.
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Affiliation(s)
- Kristen M Vogelhuber
- Space Vehicles Directorate, Air Force Research Laboratory , Kirtland AFB, New Mexico 87117, United States.,Institute for Scientific Research, Boston College , Chestnut Hill, Massachusetts 02467, United States
| | - Ryan S Booth
- Space Vehicles Directorate, Air Force Research Laboratory , Kirtland AFB, New Mexico 87117, United States.,Institute for Scientific Research, Boston College , Chestnut Hill, Massachusetts 02467, United States
| | - Christopher J Annesley
- Space Vehicles Directorate, Air Force Research Laboratory , Kirtland AFB, New Mexico 87117, United States
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18
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Brotton SJ, Lucas M, Chambreau SD, Vaghjiani GL, Yu J, Anderson SL, Kaiser RI. Spectroscopic Investigation of the Primary Reaction Intermediates in the Oxidation of Levitated Droplets of Energetic Ionic Liquids. J Phys Chem Lett 2017; 8:6053-6059. [PMID: 29183120 DOI: 10.1021/acs.jpclett.7b02669] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The production of the next generation of hypergolic, ionic-liquid-based fuels requires an understanding of the reaction mechanisms between the ionic liquid and oxidizer. We probed reactions between a levitated droplet of 1-methyl-4-amino-1,2,4-triazolium dicyanamide ([MAT][DCA]), with and without hydrogen-capped boron nanoparticles, and the nitrogen dioxide (NO2) oxidizer. The apparatus exploits an ultrasonic levitator enclosed within a pressure-compatible process chamber equipped with complementary Raman, ultraviolet-visible, and Fourier-transform infrared (FTIR) spectroscopic probes. Vibrational modes were first assigned to the FTIR and Raman spectra of droplets levitated in argon. Spectra were subsequently collected for pure and boron-doped [MAT][DCA] exposed to nitrogen dioxide. By comparison with electronic structure calculations, some of the newly formed modes suggest that the N atom of the NO2 molecule bonds to a terminal N on the dicyanamide anion yielding [O2N-NCNCN]-. This represents the first spectroscopic evidence of a key reaction intermediate in the oxidation of levitated ionic liquid droplets.
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Affiliation(s)
- Stephen J Brotton
- Department of Chemistry, University of Hawaii at Manoa , Honolulu, Hawaii 96822, United States
| | - Michael Lucas
- Department of Chemistry, University of Hawaii at Manoa , Honolulu, Hawaii 96822, United States
| | | | - Ghanshyam L Vaghjiani
- In-Space Propulsion Branch, Rocket Propulsion Division, Aerospace Systems Directorate, Air Force Research Laboratory, AFRL/RQRS , Edwards Air Force Base, California 93524, United States
| | - Jiang Yu
- Department of Chemistry, University of Utah , Salt Lake City, Utah 84112, United States
| | - Scott L Anderson
- Department of Chemistry, University of Utah , Salt Lake City, Utah 84112, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii at Manoa , Honolulu, Hawaii 96822, United States
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19
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Schmidt MW, Gordon MS. Effect of Boron Clusters on the Ignition Reaction of HNO 3 and Dicynanamide-Based Ionic Liquids. J Phys Chem A 2017; 121:8003-8011. [PMID: 28922914 DOI: 10.1021/acs.jpca.7b07996] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many ionic liquids containing the dicynamide anion (DCA-, formula N(CN)2-) exhibit hypergolic ignition when exposed to the common oxidizer nitric acid. However, the ignition delay is often about 10 times longer than the desired 5 ms for rocket applications, so that improvements are desired. Experiments in the past decade have suggested both a mechanism for the early reaction steps and also that additives such as decaborane can reduce the ignition delay. The mechanisms for reactions of nitric acid with both DCA- and protonated DCAH are considered here, using accurate wave function methods. Complexation of DCA- or DCAH with borane clusters B10H14 or B9H14- is found to modify these mechanisms slightly by changing the nature of some of the intermediate saddle points and by small reductions in the reaction barriers.
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Affiliation(s)
- Michael W Schmidt
- Department of Chemistry, Iowa State University , Ames, Iowa 50014, United States
| | - Mark S Gordon
- Department of Chemistry, Iowa State University , Ames, Iowa 50014, United States
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20
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Hsieh YT, Tsuda T, Kuwabata S. SEM as a Facile Tool for Real-Time Monitoring of Microcrystal Growth during Electrodeposition: The Merit of Ionic Liquids. Anal Chem 2017; 89:7249-7254. [DOI: 10.1021/acs.analchem.7b01596] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yi-Ting Hsieh
- Department
of Chemistry, Soochow University, Taipei City 11102, Taiwan
| | - Tetsuya Tsuda
- Department
of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
| | - Susumu Kuwabata
- Department
of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
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21
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Chambreau SD, Popolan-Vaida DM, Vaghjiani GL, Leone SR. Catalytic Decomposition of Hydroxylammonium Nitrate Ionic Liquid: Enhancement of NO Formation. J Phys Chem Lett 2017; 8:2126-2130. [PMID: 28438020 DOI: 10.1021/acs.jpclett.7b00672] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Hydroxylammonium nitrate (HAN) is a promising candidate to replace highly toxic hydrazine in monopropellant thruster space applications. The reactivity of HAN aerosols on heated copper and iridium targets was investigated using tunable vacuum ultraviolet photoionization time-of-flight aerosol mass spectrometry. The reaction products were identified by their mass-to-charge ratios and their ionization energies. Products include NH3, H2O, NO, hydroxylamine (HA), HNO3, and a small amount of NO2 at high temperature. No N2O was detected under these experimental conditions, despite the fact that N2O is one of the expected products according to the generally accepted thermal decomposition mechanism of HAN. Upon introduction of iridium catalyst, a significant enhancement of the NO/HA ratio was observed. This observation indicates that the formation of NO via decomposition of HA is an important pathway in the catalytic decomposition of HAN.
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Affiliation(s)
| | - Denisia M Popolan-Vaida
- Departments of Chemistry and Physics, University of California , Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Ghanshyam L Vaghjiani
- In-Space Propulsion Branch, Rocket Propulsion Division, Aerospace Systems Directorate, Air Force Research Laboratory, AFRL/RQRS, Edwards Air Force Base, California 93524, United States
| | - Stephen R Leone
- Departments of Chemistry and Physics, University of California , Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
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