Showing papers on "Thermal decomposition published in 1981"
TL;DR: In this article, the controlled decomposition of various metal carbonates, carboxylates, oxalates, acetates, formates and hydroxides and their common hydrates was carried out in a thermogravimetric analyzer, a differential scanning calorimeter and a differential thermal analyzer.
135 citations
TL;DR: The thermal decomposition of kraft lignin was examined by Fourier transform IR evolved gas analysis, a technique designed for on-the-fly, simultaneous monitoring of multiple vapor phase species as discussed by the authors.
Abstract: The thermal decomposition of kraft lignin was examined by Fourier-transform IR evolved-gas analysis, a technique designed for on-the-fly, simultaneous monitoring of multiple vapor-phase species. Initial degradation occurs at 120-300 degrees from bond fragmentation in the phenylpropane side chains as evidenced by the formation of HCO2H, HCHO, CO2, H2O and SO2. The presence of SO2 is supporting evidence that S from the kraft pulping process may be incorporated into the lignin structure in the form of sulfoxide and(or) sulfone linkages. Major decomposition initiates at approximately 300 degrees and extends to 480 degrees at which point half the intital weight has been lost. MeOH 2-methoxyphenol (guaiacol), and a 2-methoxy-4-alkyl- substituted phenol are the most apparent species evolving in this region and indicate fragmentation of the major chain linkages between the monomeric phenol units in the lignin structure.
128 citations
TL;DR: In this article, a mechanism for the thermal decomposition of zinc dialkyldithiophosphate additives has been proposed that accounts for the major degradation products and their dependence on the nature of the alkyl group.
Abstract: A mechanism for the thermal decomposition of zinc dialkyldithiophosphate additives has been proposed that accounts for the major degradation products and their dependence on the nature of the alkyl group. The proposed mechanism generally follows well-known rules of phosphorus chemistry. The major points are as follows. (1) The decomposition is initiated by a general migration of alkyl groups from oxygen atoms to sulfur atoms. The rate of this reaction is governed by the ease with which nucleophilic substitution can take place at the α-carbon atom of the alkyl group. The well-established correlation between decreasing number of β-hydrogen atoms and increasing thermal stability is, therefore, explicable in terms of increasing steric hindrance, by the β-subtituents, of nucleophilic attack on the α-carbon atom. (2) Olefin elimination successfully competes with substitution where the alkyl group structure is favorable (i.e. secondary alkyl groups), leading to the formation of phosphorus acids. (3) Nucleophilic...
117 citations
26 Mar 1981
TL;DR: In this paper, a thermal conduction model is used to predict the time to explosion versus reciprocal temperature curves from several heavily confined explosive tests, and good agreement is obtained between experimental and calculated explosion times for the pure explosives HMX, TATB, RDX, and TNT, mixtures such as RX-26-AF (HMX/TATB), Octol, and for PBX 9404, an HMX-based explosive containing an energetic nitrocellulose binder.
Abstract: Chemical decomposition models have been deduced from the available chemical kinetic data on the thermal decomposition of HMX, TATB, RDX, and TNT. A thermal conduction model is used in which the thermal conductivity of the reacting explosive decreases linearly with the mass fraction reacted to that of the gaseous products. These reactive heat flow models are used to predict the time to explosion versus reciprocal temperature curves from several heavily confined explosive tests. Good agreement is obtained between experimental and calculated explosion times for the pure explosives HMX, TATB, RDX, and TNT, mixtures such as RX-26-AF (HMX/TATB), Octol (HMX/TNT), and Comp B (RDX/TNT), and for PBX 9404, an HMX-based explosive containing an energetic nitrocellulose binder.
99 citations
01 Jan 1981
TL;DR: The physical, thermal, and chemical behavior of pulverized coal particles during thermal decomposition are examined for five coal types and two particle sizes for one of the bituminous coals.
Abstract: The physical, thermal, and chemical behavior of pulverized coal particles during thermal decomposition are examined for five coal types and two particle sizes for one of the bituminous coals. Particles were injected axially into a lean (35% excess air) methane/air flat flame with a nominal peak temperature of 1750°K. The significant events observed are classified by three time scales. Particles heat to the gas temperature in less than 10 msec, devolatilization occurs between 10 and 75 msec and, under the appropriate conditions, large soot particles are formed WRS and grow for times exceeding 75 msec. The events that accompany devolatilization are dependent upon coal type and particle size. For large bituminous particles (ca., 80 μm) a significant volatile fraction is ejected from the particle as a jet. This volatile jet reacts close to the particle producing a trail of small solid particles. The local heat released during the reaction of the volatiles, in combination with heterogeneous oxidation, increases the particle, temperature and raises it above that of the bulk gas stream. At later times, large soot structures, are formed which are attributed to the agglomeration of small, homogeneously formed soot on the volatile trail structures. Small bituminous particles (ca., 40 μm) burn with a higher intensity (i.e., higher temperature and more rapidly) with few trails and do not produce soot structures probably because of the more diffuse nature of the devolatilization process. Other ranks of coal exhibit different physical, thermal, and chemical behavior. For example, neither the lignites nor the anthracite produce volatile trials. Further, the particle temperature for the lignites is only slightly shifted above the bulk gas temperature in the devolatilization region while anthracite takes 50 msec to reach the bulk gas temperature level. This is attributable to the relatively low heat content of the volatiles in the former case and the low volatile content in the latter. The impact of the above observations on the formation of fuel NO is discussed.
92 citations
TL;DR: In this article, the authors studied the thermal decomposition of Green River oil shale kerogen using non-isothermal thermogravimetry and showed that first-order kinetics are adequate in explaining the overall trends in the thermal behavior of green River oil shales.
92 citations
TL;DR: In this paper, the stoichiometry, temperature dependence, and the effect of atmosphere for the thermal decomposition of Pt and Pd ammine complexes exchanged into zeolite Y were investigated by thermogravimetry.
91 citations
TL;DR: In this article, the thermal decomposition of three siderites having markedly different purities was studied using thermogravimetry, evolved gas analysis, thermomagnetometry and X-ray diffraction analysis.
87 citations
Patent•
10 Jul 1981
TL;DR: In this article, a method and apparatus for thermal decomposition of stable substances, preferably chemical hazardous waste, was proposed, which achieves a high decomposition temperature by giving the waste the necessary decomposition temperatures through the use of a plasma generated in a plasma burner.
Abstract: A method and apparatus for thermal decomposition of stable substances, preferably chemical hazardous waste. The invention achieves a high decomposition temperature by giving the waste the necessary decomposition temperature through the use of a plasma generated in a plasma burner. The waste itself can be carried through a plasma generator. Alternately, part, or all of the waste can be mixed with the plasma in a reaction chamber where decomposition takes place. The carrier gas of the plasma can be given a temperature of 3000° to 4000° C., or under certain conditions even a higher temperature. The invention also includes additional steps to eliminate toxic gases that might form during the decomposition of the waste or the cooling of the resultant gases.
85 citations
TL;DR: In this paper, it was shown that potassium carbonate, when well dispersed on a surface of carbon prepared from polyfurfuryl alcohol, decomposes at much lower temperatures than bulk carbon carbonate.
82 citations
TL;DR: In this paper, Lysergic acid was synthesized from 4-hydroxymethyl-1-tosylindole by a sequence of 9 steps and the crucial thermolysis involved the in situ generation of the transient diene III which undergoes an intramolecular cycloaddition to a C, N-double bond at 200° and at low stationary concentration of III.
Abstract: (±)-Lysergic acid (1) has been synthesized from 4-hydroxymethyl-1-tosylindole (2) by a sequence of 9 steps. The crucial thermolysis 9 10 involves the in situ-generation of the transient diene III which undergoes an intramolecular cycloaddition to a C, N-double bond at 200° and at low stationary concentration of III.
TL;DR: The thermal decomposition of sodium nitrate and the effects of several oxides, such as silica, titania, zirconia, alumina, and magnesia, on the decomposition were studied up to 900 °C by means of the thermal analysis, gas analysis, and chemical analysis of reaction products as mentioned in this paper.
Abstract: The thermal decomposition of sodium nitrate and the effects of several oxides, such as silica, titania, zirconia, alumina, and magnesia, on the decomposition were studied up to 900 °C by means of the thermal analysis, gas analysis, and chemical analysis of the reaction products. The reaction of sodium nitrate and silica was especially investigated in some detail over a wide composition range. The thermal decomposition of sodium nitrate started at about 450 °C. The gases formed were O2, NO, and N2, the formation of N2 being detected above 680 °C The thermal decomposition of sodium nitrate was supposed to consist of the following three successive or concurrent reaction processes, according to the degree of the reaction: (I) the decomposition of sodium nitrate to nitrite and oxygen, (II) the first-order liquid-phase reaction, with some kind of quantitative relationship between nitrate and nitrite, and (III) the formation reaction of sodium oxide, expressed by the Avrami-Erofe’ef equation. The (II) and (III) ...
TL;DR: In this article, the feasibility of the use of direct current electrical conductivity,σ, measurements in the study of solid-state reactions involved in the synthesis ofγ-Fe2O3 from ferrous oxalate dihydrate has been reported.
Abstract: The feasibility of the use of direct current electrical conductivity,σ, measurements in the study of solid-state reactions involved in the synthesis ofγ-Fe2O3 from ferrous oxalate dihydrate has been reported. The study has been carried out in static air, dynamic air, dry nitrogen and dynamic air + water vapour environments. The conductivity data determined in static air are quite complex; nevertheless, the formation of Fe3O4 andα-Fe2O3 with the probable intermediate formation ofγ-Fe2O3 has been indicated. In dry nitrogen the step corresponding to dehydration is well resolved in the temperature region 145–220° C; the formation of FeO and Fe3O4 is also well characterized. In dry dynamic air the reaction further proceeds to the formation ofα-Fe2O3. In dynamic air containing water vapour there are definite indications of the formation ofγ-Fe2O3 prior to the formation ofα-Fe2O3. Definite experimental conditions have been determined for the formation ofγ-Fe2O3 in dynamic air containing water vapour. The conductivity measurements have been supplemented with infra-red spectroscopy and X-ray diffraction pattern measurements. The electrical conductivity measurements were found to give additional information on the solid-state reaction to that obtained from conventional thermal analytical techniques (such as differential thermal, thermogravimetric and differential thermogravimetric analyses).γFe2O3, obtained from the decomposition of FeC2O4 · 2H2O in dynamic air + water was found to have a coercive force of 3.142 A m−1, a saturation magnetization value of 7.1 T kg−1 and a ratio of remanence to saturation magnetization of 0.64.
TL;DR: In this article, the thermal decomposition of monoclinic ammonium paratungstate (APT) and amorphous ammonium metatungst (AMT) has been studied over the temperature range 20 to 500° C using thermogravimetry, evolved gas analysis, X-ray diffraction analysis, differential thermal analysis and scanning electron microscopy.
Abstract: The thermal decomposition of monoclinic ammonium paratungstate (APT) and amorphous ammonium metatungstate (AMT) has been studied over the temperature range 20 to 500° C using thermogravimetry, evolved gas analysis, X-ray diffraction analysis, differential thermal analysis and scanning electron microscopy. A mechanism of decomposition which postulates the formation and subsequent decomposition of various lower ratio tungstates is proposed and substantiated by the experimental data.
TL;DR: In this article, a non-chain radical mechanism with rupture of the N?NO2 bond in the rate-determining stage is the most soundly based N-nitro-compound decomposition.
Abstract: Results primarily on nitramines are summarised. Analysis of modern views indicates that a non-chain radical mechanism with rupture of the N?NO2 bond in the rate-determining stage is the most soundly based. Kinetic parameters of the thermal decomposition of N-nitro-compounds are systematised. The kinetic role of phase constitution is discussed, and prospects for future research are considered. A list of 108 references is included.
TL;DR: In this paper, the effect of copper plates placed in the powder of Ca(OH)2 as heat-transfer fins was investigated experimentally and numerically, and the results showed that the Cu-plates are very effective for heat transfer and the thermal decomposition.
TL;DR: In this article, a review of the application of thermal methods of analysis, viz. differential thermal analysis (DTA), differential scanning calorimetry, thermogravimetry (TG), derivative TG (DTG), dilatometry (DT) and penetrometry (TMA), for the investigation of petroleum products (fuel and lubricating oils, greases, paraffin waxes, petrolatums and asphalts).
TL;DR: In this article, the authors investigated the thermal degradation behavior of poly(1,3-phenylene isophthalamide) and poly(chloro-2,4-phenylon isophalamide) with the aid of some appropriate model compounds.
Abstract: Thermal degradation behavior of poly(1,3-phenylene isophthalamide) and poly(chloro-2,4-phenylene isophthalamide) was investigated with the aid of some appropriate model compounds. The pyrolysis products of these materials were identified by gas chromatography (GC), gas chromatography/Fourier transform infrared spectroscopy (GC/FT-IR), and gas chromatography/mass spectrometry (GC/MS). The residual chars were characterized by IR spectroscopy. Thermogravimetric analysis (TGA) was applied to study the effect of end-group concentration on the degradation characteristics of the two polyamides. Kinetic parameters that describe the thermal degradation of the polyamides were also evaluated by TGA. The results of this investigation suggest that the thermal decomposition of these aromatic polyamides involves homolytic as well as hydrolytic cleavages of the amide units.
Patent•
05 Nov 1981
TL;DR: In this paper, stable concentrated solutions of urea and sulfuric acid containing mono-and/or diurea sulfates and less than 35 weight percent water, free of sulfamic acid and/or ammonium sulfamate, are produced by a unique process that involves the simultaneous and separate addition of Urea, SSA and optionally water to a reaction zone at controlled rates and in stochiometric proportions equivalent to the composition of the desired product, and maintaining reaction temperatures below the incipient decomposition temperature for the particular composition.
Abstract: Stable concentrated solutions of urea and sulfuric acid containing mono- and/or diurea sulfates and less than 35 weight percent water, free of sulfamic acid and/or ammonium sulfamate, are produced by a unique process that involves the simultaneous and separate addition of urea, sulfuric acid and optionally water to a reaction zone at controlled rates and in stochiometric proportions equivalent to the composition of the desired product, and maintaining reaction temperatures below the incipient decomposition temperature for the particular composition. The heat generated by the highly exothermic reaction can be removed by cooling the liquid phase during the course of the reaction by direct air heat exchange with only nominal, if any, atmospheric emissions.
TL;DR: In this paper, small metal particles in Y zeolite supercages can be prepared by the controlled thermal decomposition of binary metal carbonyls and their derivatives, and the presence of such aggregates is clearly demonstrated in the case of ruthenium.
TL;DR: The thermal decomposition of a number of TDI and MDI-based biscarbamates between 200°C and 1000°C showed that the urethane linkage undergoes an O-acyl fission at about 300°C to generate the free isocyanate and alcohol.
Abstract: The thermal decomposition of a number of TDI- and MDI-based biscarbamates (model compounds for polyurethane foams) between 200°C and 1000°C showed that the urethane linkage undergoes an O-acyl fission at about 300°C to generate the free isocyanate and alcohol. In the case of the flexible foam analogues, the newly generated TDI reacts further to generate volatile polyureas, termed ‘yellow smoke’. The MDI residues generated in the decomposition of a rigid foams react to yield non-volatile polycarbodiimides. Both the yellow smokes and the polycarbodiimides decompose above 600°C to give a mixture of nitriles (including HCN) as well as a number of olefinic and aromatic compounds. The use of 13C labeling indicated that HCN and all the other nitriles generated during the high temperature decompositions originate in the thermal fission of the aromatic ring, the nitrile carbon being the 2-, 4- or 6- carbon of MDI.
Dissertation•
01 Feb 1981
TL;DR: Thesis (ScD) as discussed by the authors, Massachusetts Institute of Technology, Dept of Chemical Engineering, 1981, Section 5.1, Section 7.2, Section 6.1.
Abstract: Thesis (ScD)--Massachusetts Institute of Technology, Dept of Chemical Engineering, 1981
Patent•
05 Nov 1981
TL;DR: In this paper, stable, urea-sulfuric acid reaction products of predetermined composition containing mono-and/or diurea sulfates and less than 35 weight percent water are produced from concentrated, URE-SURIC acid reaction product feeds of different compositions.
Abstract: Stable, urea-sulfuric acid reaction products of predetermined composition containing mono- and/or diurea sulfates and less than 35 weight percent water are produced from concentrated, urea-sulfuric acid reaction product feeds of different compositions by simultaneously and separately adding a selected feed solution and reactant urea and/or sulfuric acid, and optionally water, to a reaction zone in stoichiometric proportions so that the composition of the total feed to the reaction zone corresponds to the predetermined composition. Reaction temperature is maintained at a level below the incipient decomposition temperature of the predetermined composition, and the resulting products are essentially or completely free of sulfamic acid and/or ammonium sulfamate. Depending upon the relative proportions of unreacted sulfuric acid and urea in the total feed, the reaction may be exothermic or endothermic and, when desired, the otherwise endothermic reactions can be made exothermic by the reaction of excess urea and sulfuric acid to autogenously maintain the desired reaction temperature.
TL;DR: In this article, the thermal decomposition of ammonium heptamolybdate has been investigated, making use of additional information obtained from isothermal studies, X-ray and IR measurements.
TL;DR: In this article, the structure of iridium carbonyl complexes trapped within the zeolite cavities and the reactivity of these species towards the methanol carbonylation have been investigated.
TL;DR: In this article, a relationship was found and discussed between the values ln K≠ and ln D, where D is a detonation velocity at maximum theoretical density of the above-mentioned compounds.