DOCSLIB.ORG

Electrochemical Oxidation of Methanol, Formic Acid & Hydrazine at Pt-Ni

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Electrochemical Oxidation of Methanol, Formic Acid & Hydrazine at Pt-Ni Indian Journal of Chemistry Vol. 14A, May 1976, pp, 315-318 Electrochemical Oxidation of Methanol, Formic Acid & Hydrazine at Pt-Ni, Pt-Au & Pt-Pd Electrodes C. B. ROY, S. C. DAS & H. R. KUNDU* Department of Chemistry, Indian Institute of Technology, Kharagpur Received 23 April 1975; accepted 18 [uly 1975 Electrochemical oxidation of methanol, hydrazine and formic acid has been studied on a pure platinum electrode and platinum which has been co-deposited with Au, Pd or Ni from a platlniztng solution containing about 10% of latter metal. The polarization characteristics of the electrodes indicate that in their electro-oxidation process, the co-deposited Pt-Au, Pt-Pd, Pt-Nl act as better electrodes than platinum alone and the catalytic activity increases in the order Pt-c Pt-Ni-c Pt-Pd-c.Pt-Au. The rate determining step in these electrochemical oxidation using different electrodes is the chemtsorbed dissociative step which results in adsorbed hydro- gen which is subsequently oxidized through a fast step. It is seen that electrodes possessing higher values of heat of adsorption for hydrogen act as better electrocatalyst. ETHANOL, formic acid and hydrazine are supply connected in series to a variable resistance. important fuels because of their electro- The direct current source was connected to the M chemical reactivity. Several studies have auxiliary platinum electrode (cathode) and the been reported on the mechanism of anodic oxidation working electrode (anode) in a conventional H-type at platinum electrode of methanol-+, formic acid=? glass cell, anode and cathode compartments being and hydrazine". separated by fritted glass. In the galvanostatic A comparison of activity of noble metal alloys procedure followed, the steady state was assumed for anodic oxidation of methanol has been made such that the system varied negligibly with time by Breiter", and Dahms and Bockris'". They when measurement was taken. Under these condi- explained the difference in activities of the metal tions, it was possible to control the current externally by a difference in metal organic bond strengths and measure the resulting potential. The potential which may be related to the distinct difference of (mV) of the anode against SCE or Hg/HgO (IN heats of sublimation for the metals and the diffe- KOH) electrode was measured with the help of a rence in work function, the metal with the higher Cambridge pH-meter. A Luggin capillary was used work function exhibiting the faster reaction. to minimize IR drop. The current through the Frumkin» observed that an alloy made by simul- anode was varied stepwise, the corresponding pote~- taneous deposition of platinum and ruthenium from tial being determined. The four electrodes used m a mixture which contained 10% or less ruthenium the present study were prepared as follows: plati- was 100 times as active as pure platinum in oxida- nized Pt prepared from platinizing solution contain- tion of methanol. Grimes and Spengler= showed ing chloroplatinic acid in HCI (2N). The second that the use of mixed Pt-Pd electrode brought about one was prepared co-deposition of Pt and Au on a complete oxidation of methanol to carbonate. platinum foil from the solution of chloroplatinic McKee and Pak13 observed that Pt containing up to acid and auric chloride in HCl (2N). The solution 10·2% nickel acted as a better electrode than contains platinum and gold in the ratio of 10: 1 by platinum alone in anodic oxidation of H2 and CO wt of metals. The third and fourth electrodes were mixture containing up to 10% CO. According to prepared similarly by co-deposition of Pt/Ni and them, Pt-S% Cu, Pt-5% Sb are also better than PtjPd respectively. Nickel chloride or palladium platinum alone in the above reaction. chloride along with chloroplatinic acid in HCl (2N) The present investigation has been undertaken to were used in the preparation of the last two elec- study the activity of Pt mixed with Pd, Au or Ni trodes respectively. A current density of 15 majcm2 in electrochemical oxidation of methanol, formic for 25 min was used during electrodeposition for acid and hydrazine. all the electrodes. Basic solution of platinic chlo- ride (1%) with lead acetate (0·01%) in HCl (2N) Materials and Methods was used in all the cases. The electrochemical oxidation of methanol and The experimental scheme followed was similar to hydrazine was studied in KOH solution (IN) and that described by Wynveent! and Masaru and that of formic acid in H2S04 medium (0·5N). Hironosuke'". The galvanostatic circuit'" employed Estimation of Ni in the co-deposit was done polaro- consisted of high voltage stabilized D-C power graphlcally-? and the amount was found to be 0·479 4 2 *Present address: Central Instrumentation Service Sec- X 10- gjcm • All the chemicals used were of BDH tion, IIT, Kharagpur 2. AR grade. Triply distilled conductivity water was used. 315 INDIAN J. CHEM., VOL. 14A, MAY 1976 The anodic charging curves of the electrodes in Results and Discussion the presence of hydrogen were recorded following the procedure of Delahay and Berzins-" using Current-voltage curves at 30° for anodic oxidation Tektronix-547 oscilloscope. The glass cell was pro- of N2H4 (O·SM), and CH 0H (1M) both in KOH vided with a stopper through which 6 electrodes 3 (1M) at Pt-Au, Pt-Pd, Pt-Ni and platinized platinum were introduced and dipped into 2·5N H SO, 2 electrodes and that of formic acid (1M) in H S0 (AR H S0 ), The sulphuric acid solution was 2 4 2 4 (O·SN) are shown in Fig. 1. The results indicate preelectrolvsed with 15-50 ma current for 24 hr. that the activity of Pt in the oxidation of these Two electrodes were platinized platinum foil (1 cm2) fuels increased in the order: Pt-c.Pt-Ni-c.Pt-Pd-c.Pt- of which one was used as the reference electrode Au. It was found that higher temperature reduces and the other as counter electrode. The remaining the polarization in each case for all electrodes. four electrodes (exposed length 0·8 cm., diamete.r In acidic solution methanol could be oxidized at 0·05 cm) were platinized platinum electrode, Pt-NI, the platinum electrode to carbon dioxide and water, Pt-Au and Pt-Pd electrodes used as anodes. The and in alkaline solution the main oxidation product cell was also provided with an inlet and outlet for was reported to be formate ion", A mechanism of purified hydrogen gas. A constant current was electrochemical oxidation of methanol was proposed passed through the anode and the. counter elec~rode by Pavela- and later supported in a similar form by by means of a mercury switch. The mput Buck and Griffiths. The mechanism of oxidation attenuater of 'Y' amplifier was set at 0·5 Vfcm a?-d the time base switch at 5 msecjcm. The potential proposed for alkaline media may be written as: of the experimental electrode was ref~rred to that CHaOH+OH- ~ CH30-+H20 ... (1) of a platinized platinum electrode 111 the same Pt solution, which might be considered as hydrogen CH30- --+ CH20-(ad) + Had ..• (2) electrode. The oscilloscopic trace was photographed slow by means of Du Mont oscilloscopic camera type fast 2615. Had+OH- --+ H20+e- ...(~) .....•. -I'O~-----------------, :r -O~.~------------------------- -, -... A· o B % o " ~" -0'9 o..- .•.•%.. .•.. 2 x -0'8 '"> 2!. ~ ....I ....I ~ -0'7 ~ -0'2 u ~ z ...z ...~ ~ o o .•. e, -o~Lo -----i20 -40----~----~----~~--~IOO~60 80 o 20 40 60 80 100 ml (U'RRENT DENSITY(ma/Cm2) CURRENT DEN5ITy(ma/C ) c ••...•. ..; +0'5 ... v '" U> > ..:>....• +0'3 Fig. 1 -- Current-voltage curves for anodic oxida- ....I tion of (A)' N,H. (O'SM), (B) CH"OH (1M) and (C) ..• HCOOH (lj1f) at different electrodes A and B in ~ KOH (11\1/) and C in H2S04 (O'05N) at 30° [(1) Pt- z Au; (2) Pt-Pd ; (3) Pt-Ni ; and (4) platinized Pt] ~~Ol .i->:" _::l:::~o m ~ W W 00 CURRENT DENSITY (m a/cm2) 316 ROY et al.: OXIDATION OF METHANOL, FORMIC ACID & HYDRAZINE From the experimental observation of Langmuir and Au are 71·4 and 71·3 kcal/mole respectively. type adsorption and a Tafel slope of 2RTjF, the So it is expected that !1H ads will incr~ase by: the first electron transfer-? is indicated as the rate presence of any of these metals along with platinum determining step, where dissociative chemisorption during co-deposition. step is involved. The increase in activity of platinized platinum In the decomposition of formic acid, Schwab" electrode co-deposited with any of the three metals proposed a mechanism which consisted of adsorption Au, Ni and Pd is indicated from the reduced of molecular formic acid, decomposition to carbon polarization of the electrode, ~he .or~er bein~: dioxide and adsorbed hydrogen, and hydrogen Pt<Pc-Ni<Pt-Pd<Pt-Au. If dissociative chemi- desorption. Gottlieb? reported Tafel slope of 2RTjF sorption is the rate determining step, it is expected that the presence of Au, Pd or Ni in Pt will increase in oxidation of formic acid in H2S04 and proposed preliminary decomposition of formic acid and s.ub- the rate of oxidation of above species since !1Hads sequent oxidation of hydrogen. The mechamsm would increase bv the presence of these elements may be represented by Eqs. (4_7)6,20. with platinum. !1Hads values may be compared at zero coverage (free surface) with respect to the HCOOHso1n ~ HCOOHad ... (4) reacting species. r.d.s , Results of anodic charging curves of the different HCOOHad --7 HCOOad+Had . .. (5) electrodes are represented in oscilloscopic traces Had -7 H++e- ..
Load more

Recommended publications
  • Supporting Information For
    Electronic Supplementary Material (ESI) for Chemical Communications This journal is © The Royal Society of Chemistry 2011 Supporting Information for: 2- Quadruple-CO3 Bridged Octanuclear Dysprosium(III) Compound Showing Single-Molecule Magnet Behaviour Experimental Section Synthetic procedures All chemicals were of reagent grade and were used without any further purification. Synthesis of pyrazine-2-carbohydrazide The pyrazine-2-carboxylic acid methyl ester was prepared by a literature procedure described elsewhere. A mixture of pyrazine-2-carboxylic acid methyl ester (1.38 g, 10 mmol) and hydrazine hydrate (85%, 15 ml) in methanol (20 ml) was refluxed overnight, at a temperature somewhat below 80°C. The resulting pale-yellow solution set aside 12 hrs. During this period, a colorless product, i.e. pyrazine-2-carbohydrazide, precipitated from the reaction mixture as a crystalline solid (yield = 0.84 g, 61%). Synthesis of (E)-N'-(2-hyborxy-3-methoxybenzylidene)pyrazine-2-carbohydrazide Pyrazine-2-carbohydrazide (2 mmol, 0.276 g) was suspended together with o-vanillin (2 mmol, 0.304 g) in methanol (20 ml), and the resulting mixture was stirred at the room temperature overnight. The pale yellow solid was collected by filtration (yield = 0.56 g, 83%). Elemental analysis (%) calcd for C13H12N4O3: C, 57.35, H, 4.44, N, 20.58: found C, 57.64, H, 4.59, N, 20.39. IR (KBr, cm-1): 3415(w), 3258(w), 1677(vs), 1610(s), 1579(m). 1530(s), 1464(s), 1363(m), 1255(vs), 1153(s), 1051(w), 1021(s), 986(w), 906(m), 938(w), 736(s), 596(m), 498(w). Synthesis of the complex 1 The solution of DyCl3⋅6H2O (56.5 mg, 0.15 mmol) and the H2L (40.5 mg, 0.15 mmol) in 15 ml CH3OH/CH2Cl2 (1:2 v/v) was stirred with triethylamine (0.4 mmol) for 6h.
    [Show full text]
  • Hydrous Hydrazine Decomposition for Hydrogen Production Using of Ir/Ceo2: Effect of Reaction Parameters on the Activity
    nanomaterials Article Hydrous Hydrazine Decomposition for Hydrogen Production Using of Ir/CeO2: Effect of Reaction Parameters on the Activity Davide Motta 1, Ilaria Barlocco 2 , Silvio Bellomi 2, Alberto Villa 2,* and Nikolaos Dimitratos 3,* 1 Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK; [email protected] 2 Dipartimento di Chimica, Università degli Studi di Milano, 20133 Milano, Italy; [email protected] (I.B.); [email protected] (S.B.) 3 Dipartimento di Chimica Industriale e dei Materiali, Alma Mater Studiorum Università di Bologna, 40136 Bologna, Italy * Correspondence: [email protected] (A.V.); [email protected] (N.D.) Abstract: In the present work, an Ir/CeO2 catalyst was prepared by the deposition–precipitation method and tested in the decomposition of hydrazine hydrate to hydrogen, which is very important in the development of hydrogen storage materials for fuel cells. The catalyst was characterised using different techniques, i.e., X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with X-ray detector (EDX) and inductively coupled plasma—mass spectroscopy (ICP-MS). The effect of reaction conditions on the activity and selectivity of the material was evaluated in this study, modifying parameters such as temperature, the mass of the catalyst, stirring speed and concentration of base in order to find the optimal conditions of reaction, which allow performing the test in a kinetically limited regime. Citation: Motta, D.; Barlocco, I.; Bellomi, S.; Villa, A.; Dimitratos, N. Keywords: iridium; cerium oxide; hydrous hydrazine; hydrogen production Hydrous Hydrazine Decomposition for Hydrogen Production Using of Ir/CeO2: Effect of Reaction Parameters on the Activity.
    [Show full text]
  • Periodic Trends in the Main Group Elements
    Chemistry of The Main Group Elements 1. Hydrogen Hydrogen is the most abundant element in the universe, but it accounts for less than 1% (by mass) in the Earth’s crust. It is the third most abundant element in the living system. There are three naturally occurring isotopes of hydrogen: hydrogen (1H) - the most abundant isotope, deuterium (2H), and tritium 3 ( H) which is radioactive. Most of hydrogen occurs as H2O, hydrocarbon, and biological compounds. Hydrogen is a colorless gas with m.p. = -259oC (14 K) and b.p. = -253oC (20 K). Hydrogen is placed in Group 1A (1), together with alkali metals, because of its single electron in the valence shell and its common oxidation state of +1. However, it is physically and chemically different from any of the alkali metals. Hydrogen reacts with reactive metals (such as those of Group 1A and 2A) to for metal hydrides, where hydrogen is the anion with a “-1” charge. Because of this hydrogen may also be placed in Group 7A (17) together with the halogens. Like other nonmetals, hydrogen has a relatively high ionization energy (I.E. = 1311 kJ/mol), and its electronegativity is 2.1 (twice as high as those of alkali metals). Reactions of Hydrogen with Reactive Metals to form Salt like Hydrides Hydrogen reacts with reactive metals to form ionic (salt like) hydrides: 2Li(s) + H2(g) 2LiH(s); Ca(s) + H2(g) CaH2(s); The hydrides are very reactive and act as a strong base. It reacts violently with water to produce hydrogen gas: NaH(s) + H2O(l) NaOH(aq) + H2(g); It is also a strong reducing agent and is used to reduce TiCl4 to titanium metal: TiCl4(l) + 4LiH(s) Ti(s) + 4LiCl(s) + 2H2(g) Reactions of Hydrogen with Nonmetals Hydrogen reacts with nonmetals to form covalent compounds such as HF, HCl, HBr, HI, H2O, H2S, NH3, CH4, and other organic and biological compounds.
    [Show full text]
  • Dihydrazides - the Versatile Curing Agent for Solid Dispersion Systems
    Dihydrazides - The Versatile Curing Agent for Solid Dispersion Systems Abe Goldstein A&C Catalysts, Inc Abstract This paper will introduce dihydrazides, a relatively obscure class of curing agents useful in virtually all thermoset resin systems. First described in 1958, by Wear, et al.(1) dihydrazides are useful curing agents for epoxy resins, chain extenders for polyurethanes, and excellent crosslinking agents for acrylics. In one-part epoxy systems, depending on the backbone chain of the chosen dihydrazide, Tg's over 150°C and pot life over 6 months as cure time of less than a minute can be seen. In acrylic emulsions, dihydrazides can be dissolved into the water phase and serve as an additional crosslinker, as the emulsion coalesces and cures. As a chain extender for poylurethanes, dihydrazides can be used to increase toughness and reduce yellowing. Introduction O O | | | | Dihydrazides are represented by the active group: H2NHNC(R) CNHNH2, where R is can be any polyvalent organic radical preferably derived from a carboxylic acid. Carboxylic acid esters are reacted with hydrazine hydrate in an alcohol solution using a catalyst and a water extraction step. The most common dihydrazides include adipic acid dihydrazide (ADH), derived from adipic acid, sebacic acid dihydrazide (SDH), valine dihydrazide (VDH), derived from the amino acid valine, and isophthalic dihydrazide (IDH). The aliphatic R group can be of any length. For example, when R group is just carbon, the resulting compound is carbodihydrazide (CDH), the fastest dihydrazide. Or R as long as C-18 has been reported as in icosanedioic acid dihydrazide (LDH). Some of the more common dihydrazides are represented in Figure 1.
    [Show full text]
  • Hydrazine, Monomethylhydrazine, Dimethylhydrazine and Binary Mixtures Containing These Compounds
    Fluid Phase Behavior from Molecular Simulation: Hydrazine, Monomethylhydrazine, Dimethylhydrazine and Binary Mixtures Containing These Compounds Ekaterina Elts1, Thorsten Windmann1, Daniel Staak2, Jadran Vrabec1 ∗ 1 Lehrstuhl f¨ur Thermodynamik und Energietechnik, Universit¨at Paderborn, Warburger Straße 100, 33098 Paderborn, Germany 2 Lonza AG, Chemical Research and Development, CH-3930 Visp, Switzerland Keywords: Molecular modeling and simulation; vapor-liquid equilibrium; Henry’s law constant; Hy- drazine; Monomethylhydrazine; Dimethylhydrazine; Argon; Nitrogen; Carbon Monoxide; Ammonia; Water Abstract New molecular models for Hydrazine and its two most important methylized derivatives (Monomethyl- hydrazine and Dimethylhydrazine) are proposed to study the fluid phase behavior of these hazardous compounds. A parameterization of the classical molecular interaction models is carried out by using quan- tum chemical calculations and subsequent fitting to experimental vapor pressure and saturated liquid density data. To validate the molecular models, vapor-liquid equilibria for the pure hydrazines and binary hydrazine mixtures with Water and Ammonia are calculated and compared with the available experimen- tal data. In addition, the Henry’s law constant for the physical solubility of Argon, Nitrogen and Carbon Monoxide in liquid Hydrazine, Monomethylhydrazine and Dimethylhydrazine is computed. In general, the simulation results are in very good agreement with the experimental data. ∗ corresponding author, tel.: +49-5251/60-2421, fax: +49-5251/60-3522, email: [email protected] 1 1 Introduction On October 24, 1960, the greatest disaster in the history of rocketry, now also known as Nedelin disaster, occurred [1–3]. At that time, the Soviet newspapers published only a short communique informing that Marshall of Artillery Mitrofan Nedelin has died in an airplane crash.
    [Show full text]
  • Ethane / Nitrous Oxide Mixtures As a Green Propellant to Substitute Hydrazine: Validation of Reaction Mechanism C
    Ethane / Nitrous Oxide Mixtures as a Green Propellant to Substitute Hydrazine: Validation of Reaction Mechanism C. Naumann*, C. Janzer, U. Riedel German Aerospace Center (DLR), Institute of Combustion Technology Pfaffenwaldring 38-40, 70569 Stuttgart, Germany Abstract The combustion properties of propellants like ethane / nitrous oxide mixtures that have the potential to substitute hydrazine or hydrazine / dinitrogen tetroxide in chemical propulsion systems are investigated. In support of CFD- simulations of new rocket engines powered by green propellants ignition delay times of ethane / nitrous oxide mixtures diluted with nitrogen have been measured behind reflected shock waves at atmospheric and elevated pressures, at stoichiometric and fuel-rich conditions aimed for the validation of reaction mechanism. In addition, ignition delay time measurements of ethene / nitrous oxide mixtures and ethane / O2 / N2 - mixtures with an O2:N2 ratio of 1:2 as oxidant at the same level of dilution are shown for comparison. Finally, the ignition delay time predictions of a recently published reaction mechanism by Glarborg et al. are compared with the experimental results. Introduction waves at initial pressures of pnominal = 1, 4, and 16 bar. Hydrazine and hydrazine derivatives like The results are compared to ignition delay time monomethyl hydrazine (MMH) and unsymmetrical measurements of stoichiometric C2H4 / N2O mixtures dimethyl hydrazine (UDMH) are used for spacecraft (see [6], [7], [8]). Complementary, ignition delay times propulsion applications in various technological of the corresponding oxygen based reactive mixture contexts despite their drawback of being highly toxic. C2H6 / (1/3 O2 + 2/3 N2) have been measured, too. Today, hydrazine consumption for European space Thereafter, the predictions of a recently published activities is on the order of 2-5 tons per year.
    [Show full text]
  • HYDRAZINE Method Number: 108 Matrix: Air Target Concentration
    HYDRAZINE Method number: 108 Matrix: Air Target concentration: 10 ppb (13 µg/m3) and 1 ppm (1.3 mg/m3) OSHA PEL: 1 ppm (1.3 mg/m3) ACGIH TLV: 10 ppb (13 µg/m3) Procedure: Samples are collected closed-face by drawing known volumes of air through sampling devices consisting of three-piece cassettes, each containing two sulfuric acid treated 37-mm glass fiber filters separated by the ring section. The filters are extracted with a buffered EDTA disodium solution. An aliquot of the extract is derivatized with a benzaldehyde solution to form benzalazine from any hydrazine in the samples. The benzalazine is quantitated by LC using a UV detector. Recommended air volume and sampling rate: 240 L at 1.0 L/min Reliable quantitation limit: 0.058 ppb (0.076 µg/m3) Standard error of estimate at the target concentration: 7.5% at 10 ppb Target Concentration 5.2% at 1 ppm Target Concentration Status of method: Evaluated method. This method has been subjected to the established evaluation procedures of the Organic Methods Evaluation Branch. Date: February 1997 Chemist: Carl J. Elskamp Organic Methods Evaluation Branch OSHA Salt Lake Technical Center Salt Lake City, UT 84165-0200 1 of 19 T-108-FV-01-9702-M 1. General Discussion 1.1 Background 1.1.1 History In 1980, an air sampling and analytical procedure to determine hydrazine was validated by the OSHA Analytical Laboratory. (Ref. 5.1) The method (OSHA Method 20) is based on a field procedure developed by the U.S. Air Force that involves collection of samples using sulfuric acid coated Gas Chrom R and colorimetric analysis using p¯dimethylaminobenzaldehyde.
    [Show full text]
  • Unsymmetrical Dimethylhydrazine (UDMH) Technical Data Sheet
    Technical Performance Chemicals Product Hydrazine Information Unsymmetrical Dimethylhydrazine (UDMH) Unsymmetrical dimethylhydrazine (1,1-dimethylhydrazine) chemicals). It has also been used in acidic gas absorbers and is a clear, colorless hygroscopic liquid. It has an ammonia- as a fuel additive stabilizer. like odor which closely resembles that of aliphatic amines. UDMH is miscible with water, hydrazine, Handling, Storage and Safety dimethylenetriamine, ethanol, amines and most petroleum fuels. The experience accumulated by the chemical and aerospace industries indicates that with rigid adherence to proper UDMH is mildly alkaline and is a very strong reducing precautions, UDMH can be handled safely. Because UDMH agent. Its high chemical reactivity, easily-controlled vapors have such a very wide range of explosive limits and functionality and strong hydrogen bonding are its most useful because UDMH liquid is extremely reactive with many properties. materials, the safety precautions outlined are necessary to avoid fire or explosions. Table 1 Specifications In addition, prolonged exposure to UDMH vapor, contact % by with skin, or ingestion may produce harmful or fatal effects. Component Weight 1,1-dimethylhydrazine, min 98.0 Storage : UDMH may be stored in the DOT-approved Amines and water, max 2.0 container in which it is shipped. (See Shipping Information below.) Store away from heat, sparks, open flame and Table 2 Typical Physical Properties oxidants. Store only in well-ventilated areas. Do not contaminate. Density @ 25'C (g/ml) 0.784 (lb/gal) 6.6 Since UDMH is stable, it can be stored without loss of Viscosity @ 20'C (cp) 0.56 purity. Keep the container closed securely.
    [Show full text]
  • Thermo-Reversible Gelation of Aqueous Hydrazine for Safe Storage of Hydrazine
    technologies Article Thermo-Reversible Gelation of Aqueous Hydrazine for Safe Storage of Hydrazine Bungo Ochiai * and Yohei Shimada Department of Chemistry and Chemical Engineering, Faculty of Engineering, Yamagata University, Jonan 4-3-16, Yonezawa, Yamagata 992-8510, Japan; [email protected] * Correspondence: [email protected]; Tel.: +81-238-26-3092 Received: 5 September 2020; Accepted: 9 October 2020; Published: 12 October 2020 Abstract: A reversible gelation–release system was developed for safe storage of toxic hydrazine solution based on gelation at lower critical solution temperature (LCST). Poly(N-isopropylacrylamide) (PNIPAM) and its copolymer could form gels of 35wt% hydrazine by dissolution under low temperature and storage at ambient temperatures. For example, PNIPAM gelled a 63 fold heavier amount of 35wt% hydrazine. Aqueous hydrazine was released from the gels by compression or heating, and the gelation–release cycles proceeded quantitatively (> 95%). The high gelation ability and recyclability are suitable for rechargeable systems for safe storage of hydrazine fuels. Keywords: hydrazine; gel; LCST; fuel cell; poly (N-isopropylacrylamide) 1. Introduction Hydrazine and its derivatives contain high energy and have been applied as fuels and propellants of artificial satellites, space vehicles, and fighter jets [1–5]. Another potential application is a fuel for hydrazine fuel cells (HFCs) [6–19]. HFCs using aqueous solutions with 10%–15% of hydrazine can exhibit outputs as high as those of typical hydrogen fuel cells. Furthermore, the low corrosion of the basic media enables use of accessible materials for both electrocatalysts and electrolyte membranes, namely Co, Ni, Ag, and carbon electrodes and non-fluorine polymer membranes, which cannot be used in hydrogen and methanol fuel cells requiring highly acidic media.
    [Show full text]
  • Ucri, 100554 Preprint
    UCRI, 100554 PREPRINT x CHEMICAL THERMODYNAMICS OF TECHNETIUM 0 r0 0 0m 0 Joseph A.' Rard z C w1 m This paper was prepared for inclusion in the book CHEMICAL THERMODYNAMICS OF TECHNETIUM (to' be published by the Nuclear Energy Agency, Paris, France) February 1989 This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author. - DISCILAIMER This document was prepared as an account of work sponsored by asnagency of the United States Government Neither the United States Government nor the University of California nor any of their employees. makes any warranty, express or implieid, or assumes any legal liability or responsibility for the accuracy completeness, or useful- ness of any Information, apparatus. product, or process disclosed. or represents that Its use would not Iafringe privately owned rights. Reference hereln to any specific commercial products, process, or service by trade name. trademark. manufacturer, or otherwise. does not necessarily constitute or Imply its endorsement. recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed hereb do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. -W This manuscript by JA Rard is to be part of a book entitled "CHEMICAL THERMODYNAMICS OF TECHNETIUM". It will be published by the Nuclear Energy Agency Data Bank at Saclay, France.
    [Show full text]
  • Oxidation of Hydrazine by Alkaline Ferricyanide in Water-Methanol Mixtures V
    188 V. K. JINDAL, M. C. AGRAWAL, AND S. P. MUSHRAN Oxidation of Hydrazine by Alkaline Ferricyanide in Water-methanol Mixtures V. K. Jin d a l , M. C. A graw al , and S. P. M ush ra n Department of Chemistry, University of Allahabad, Allahabad, India (Z. Naturforsdi. 25 b, 188—190 [1970] ; eingegangen am 2. September 1969) Kinetics of the oxidation of hydrazine by ferricyanide was investigated in water-methanol mix­ tures using several buffer solutions. The reaction showed first order dependence in both hydrazine and ferricyanide. The order with respect to hydroxide ion concentration was zero. Increase in con­ centration of methanol had a retarding influence on the rate while the addition of neutral salts showed a specific ion effect. The energy and entropy of activation were calculated as 12.3 kcals. mole- 1 and — 20.8 cals. deg-1 mole-1 respectively. A suitable mechanism has been proposed which suggests the primary rate determining reaction between N2H4 and Fe(CN)63e. Nitrogen was found to be the product of the reaction. Hydrazine and its derivatives have been exten­ Several buffer solutions were prepared by mixing sively used as reducing titrants in both acidic and suitable amounts of sodium carbonate and bicarbonate (0.2 m ) and final pH was adjusted in 50% methanol. alkaline media.1 The principal product of the oxi­ The following table gives the pH of the buffers employed dation is nitrogen. A little work has been done on in aqueous and 50% methanolic solutions. the kinetics of the oxidation of hydrazine in alkaline solutions 2.
    [Show full text]
  • Nanocatalysts for Hydrogen Generation from Ammonia Borane and Hydrazine Borane
    Hindawi Publishing Corporation Journal of Nanomaterials Volume 2014, Article ID 729029, 11 pages http://dx.doi.org/10.1155/2014/729029 Review Article Nanocatalysts for Hydrogen Generation from Ammonia Borane and Hydrazine Borane Zhang-Hui Lu, Qilu Yao, Zhujun Zhang, Yuwen Yang, and Xiangshu Chen College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, China Correspondence should be addressed to Zhang-Hui Lu; [email protected] and Xiangshu Chen; [email protected] Received 15 February 2014; Accepted 26 February 2014; Published 14 April 2014 Academic Editor: Ming-Guo Ma Copyright © 2014 Zhang-Hui Lu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Ammonia borane (denoted as AB, NH3BH3) and hydrazine borane (denoted as HB, N2H4BH3), having hydrogen content as high as 19.6 wt% and 15.4 wt%, respectively, have been considered as promising hydrogen storage materials. Particularly, the AB and HB hydrolytic dehydrogenation system can ideally release 7.8 wt% and 12.2 wt% hydrogen of the starting materials, respectively, showing their high potential for chemical hydrogen storage. A variety of nanocatalysts have been prepared for catalytic dehydrogenation from aqueous or methanolic solution of AB and HB. In this review, we survey the research progresses in nanocatalysts for hydrogen generation from the hydrolysis or methanolysis of NH3BH3 and N2H4BH3. 1. Introduction 19.6 wt% and a low molecular weight (30.9 g/mol), exceeding that of gasoline and Li/NaBH4, has made itself an attractive Hydrogen, as a globally accepted clean and source-independ- candidate for chemical hydrogen storage applications [14].
    [Show full text]