Search results for " pyrolysis"
showing 10 items of 49 documents
Manure as a potential source of renewable energy: The behaviour and characterisation of biofuels generated from three animal manure types when subjec…
2020
Regions with high livestock density lack sufficient land on which to apply manure without exceeding the legal limits set by the European Union Directives. The lack of manure processing alternatives aggravates the situation, especially in the case of islands. Consequently, manure becomes a liability rather than an asset. Results indicate that pyrolysis is an option for manure processing. However, a significant limitation is the moisture content of the starting material, that could compromise the process efficiency. Yields of biogas, bio-oil and biochar, all of which have a potential use as biofuels, are particular to animal type and manure handling system. The conversion of manure to biofuel…
Slow pyrolysis of an LDPE/PP mixture: Kinetics and process performance
2021
Abstract High- and low-density polyethylene (HDPE and LDPE) and polypropylene (PP) are the most common polymers among plastic waste as they have multiple commercial applications. This study focused on thermal degradation characteristics and kinetic of a plastic mixture with a composition of 92.5 wt% LDPE and 7.5% PP. Thermal decomposition characteristics of the plastic mixture was analysed through thermo-gravimetric analysis (TGA). The overall kinetic of the process was studied using the modified Coats−Redfern method and the Ozawa-Flynn-Wall (OFW) method. The apparent activation energy (E) and pre-exponential factor (A) obtained were 316.0 kJ/mol; 8.09E+21 min−1 and 311.5 kJ/mol; 4.35E+21 m…
Spray pyrolysis synthesis and characterization of Mg1-xSrxMoO4 heterostructure with white light emission
2020
[EN] Molybdates are inorganic materials with great potential in white phosphors application, being an alternative to traditional lighting sources. In this study, we report the synthesis and characterization of Mg1-xSrxMoO4 (x = 0, 0.25, 0.50, 0.75, and 1) powders with white light-emitting properties. Using X-ray diffraction, the formation of the monoclinic beta-MgMoO4 phase was observed for x = 0 and the formation of the tetragonal scheelite phase of SrMoO4 was observed for x = 1. The formation of a heterostructure composed of both phases was found for compositions with x = 0.25, 0.50 and 0.75. Scanning and trasmission electron microscopy images showed that the Mg1-xSrxMoO4 particles exhibi…
Naphthothiete und ihre Anwendung in der Heterocyclen-Synthese
1995
Naphtothietes and Their Application to the Synthesis of Heterocycles The three isomeric naphthothietes 5, 11, and 16 were prepared according to the reaction sequences shown in Schemes 1–3. The final step was in each case a flash vacuum pyrolysis (FVP) of the corresponding mercaptonaphthalenemethanol 4, 9, and 15, respectively. The thiete rings in 5 and 11 can be opened by gentle heating; the ring opening of the isomer 16 possesses a much higher activation barrier. A MNDO calculation of the ΔHf values of 5, 11, and 16 and the open isomers 5′, 11′, and 16′ provides an explanation for the different behavior. Photochemical ring opening represents a useful alternative. The reaction Schemes 4, 6,…
Pyrolysis gas chromatography-mass spectrometry in environmental analysis: Focus on organic matter and microplastic
2020
Pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) has great potential within environmental analysis. This technique is mainly used for the chemical identification of macromolecules that cannot be characterized by either liquid or gas chromatography due to their big size. Through pyrolysis (controlled thermal degradation), these macromolecules are broken down into simpler molecules that can be separated by gas chromatography and detected by mass spectrometry. This technique has been traditionally used in environmental samples for the characterization of organic matter and humic substances, contaminants, lignins, etc. It attains the identification of the different types of chemical un…
Generation and transformation of the [3.3.1]propellane skeleton by thermal rearrangements
1994
Abstract In a sequence of unexpected thermal rearrangements the strained monocyclic alkyne 4 is transformed into the tricyclic system 5 which yields in a flash vacuum pyrolysis again a monocyclic compound 10 .
Thermal Rearrangements of Perchlorohexatrienes-Structures and Experimental and Theoretical Evaluation of Pathways to Isomerization and Cyclization
2009
We have prepared trans- (1) and cis-octachloro-1,3,5-hexatriene (2) by known routes and studied their thermal behavior experimentally and theoretically by ab initio calculations. The three double bonds in 1 and 2 are completely decoupled due to steric hindrance by the eight Cls, as indicated by calculations as well as the single-crystal X-ray structure of 1. The cis isomer 2 can be isomerized to the trans isomer 1 by heating it to 220–250 °C either neat or dissolved in high-boiling solvents, leading to a roughly 2:1 mixture of trans and cis isomers. Calculations at several different levels of theory predict 1 and 2 to be isoenergetic within 2 kJ mol–1. Unimolecular cis/trans isomerization i…
ChemInform Abstract: Benzoxetes and Benzothietes - Heterocyclic Analogues of Benzocyclobutene
2012
Benzo-condensed four-ring heterocycles, such as benzoxetes 1 and benzothietes 3 represent multi-purpose starting compounds for the preparation of various higher heterocyclic ring systems. The thermal or photochemical valence isomerizations between the benzenoid forms 1,3 and the higher reactive o-quinoid structures 2,4 provide the basis for the synthetic applications. On the other hand, this valence isomerization impedes in particular the generation and storage of 1 because the thermal equilibrium 1 2 is completely on the side of 2. Thus, the number of erroneous or questionable benzoxete structures published to date is surprisingly high. On the contrary, the thermal equilibrium 3 4 is on th…
An alternative route to 2H-naphtho[1,2-b]thiete and its cycloaddition products
1998
2-(1H-Benzotriazol-1-ylmethyl)-1-naphthalenol (1) can be transformed in high yields to the corresponding thiol 4. Flash vacuum pyrolysis of 4 leads to 2H-naphtho[1,2-b]thiete (5). The benzotriazolyl group proved to be a good leaving group; however, a subsequent nitrogen extrusion takes place under flash vacuum pyrolysis conditions and cyclopentadienecarbonitriles 6a,b are formed by a ring contraction (Scheme 1). Cycloaddition reactions of 5 and dienophiles or heterodienophiles yield the naphtho-condensed sulfur heterocycles 8, 10, 12 and 14 (Scheme 2).
Thermal rearrangements of 1,2-dialkoxybenzenes by flash vacuum pyrolysis
1995
Flash vacuum pyrolysis of 1,2-dialkoxybenzenes 1a-c leads to the liberation of alkanes from the interacting side chains. A rearrangement of the skeleton yields the o-hydroxy carbonyl compounds 2 and 4. The generation of phenol 3 can be rationalized by a decarbonylation. The latter reaction is the sole process which can be observed for the bicyclic starting compound 9.