Search results for "Pyrolysis"
showing 10 items of 170 documents
Evidence for the formation of 1,3- and 1,4-dehydrobenzenes in the thermal decomposition of diaryliodonium-carboxylates
1986
Abstract Abstract: Generation of m- and p-benzynes in decomposition of diaryliodonium- 3- and 4-carboxylates is demonstrated by three-phase method.
Strukturuntersuchung von polyestern durch direkten abbau im massenspektrometer, 1. Polyester der terephthalsäure
1976
Die Abbaureaktionen von Poly(athylenterephthalat) (1a), Poly(tetradeuteroathylenterephthalat) (1b), Poly(trimethylenterephthalat) (1c) und Poly(tetramethylenterephthalat) (1d) im Massenspektrometer wurden untersucht. Hierzu wurden die Polymeren direkt in der Ionenquelle des Massenspektrometers pyrolysiert und die entstehenden thermischen Bruchstucke durch Elektronenstos ionisiert und fragmentiert. Die thermisch- und elektronenstosinduzierten Abbaureaktionen lassen sich nebeneinander nachweisen. Die untersuchten polymeren Terephthalate 1a–d folgen in beiden Abbauschritten den gleichen Mechanismen und konnen anhand ihrer Pyrolyse-Massenspektren unterschieden werden. The degradation reactions …
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.
Characterization of totally chlorine-free effluents from kraft pulp bleaching III
1999
Abstract Chemical changes in the dissolved high-molecular-mass material from silver birch (Betula pendula) kraft pulp during the oxygen–alkali delignification stage (O) and the subsequent totally chlorine-free (TCF) bleaching sequence (X–Z–EOP–AZ–EP–S) were investigated by analytical pyrolysis (pyrolysis–gas chromatography/mass-sensitive detector (Py–GC/MSD)). In addition, the pyrolysis data were subjected to chemometric analysis, resulting in a rapid method for determining with reasonable accuracy, for example, the mass proportion of carbohydrates and lignin in the effluents from each of the treatment stages. The method was calibrated by chemical analysis on the same effluents.
Generation of hexahydroazulenes
2009
(Z)-Cyclodec-1-en-6-yne (3) generates three conjugated hexahydroazulenes 3→1k→1c, 1l under FVP conditions, whereas flash vacuum pyrolysis (FVP) of cyclodecyne (2) leads to 1,2,9-decatriene (9). We attribute the different thermal behavior of 2 (ring opening) and 3 (ring closure) to different transannular interactions. Altogether 22 constitutional isomers of hexahydroazulene should exist; three new isomers (1k, 1l, and 1m) are presented here, ten were described earlier, but the reinvestigation of the dehydration route of bicyclic alcohol 11 showed that one of the ten structures has to be revised.
Über den thermischen abbau des poly(ɛ-caprolacton)s
1977
The thermal and electron impact induced degradation reactions of poly(e-caprolactone) {poly[oxy(1-oxohexamethylene)]} were investigated in a mass spectrometer. It can be shown that the favorated thermal degradation reaction is the cleavage of the ester bond and formation of ω-hydroxyl and ketene endgroups (Eq. (iii)) and with a lower intensity the cleavage of the OCH2-bond and formation of carboxyl-and pentenyl endgroups (Eq. (vii)). After electron impact and fragmentation of the pyrolysis products to carboxonium ions an elimination of caprolactone via a “zip”-mechanism can be observed (Eq. (v)).
Modeling the influence of potassium content and heating rate on biomass pyrolysis
2017
This study presents a combined kinetic and particle model that describes the effect of potassium and heating rate during the fast pyrolysis of woody and herbaceous biomass. The model calculates the mass loss rate, over a wide range of operating conditions relevant to suspension firing. The shrinking particle model considers internal and external heat transfer limitations and incorporates catalytic effects of potassium on the product yields. Modeling parameters were tuned with experimentally determined char yields at high heating rates (>200 K s−1) using a wire mesh reactor, a single particle burner, and a drop tube reactor. The experimental data demonstrated that heating rate and potassium …
Valorization potential of technical lignins from Norway spruce (Picea abies) via pyrolysis
2022
Analytical pyrolysis (Py-GC/MS) on mg-scale of Norway spruce (Picea abies)-derived kraft lignin, ethanosolv lignin, and dried lignin-rich soda-anthraquinone (AQ) black liquors was studied at 500 °C to compare the valorization potential of these materials, focusing on the type and yield of condensable pyrolysis products. Of particular interest was the relatively selective formation of guaiacol (2-methoxyphenol) from the dried soda-AQ black liquors in contrast to the formation of complex phenolic product mixtures from the pyrolysis of the kraft and ethanosolv lignins. It was shown that this finding could be attributed to differences in composition and structure as was assessed by various NMR …
Fourfold Increase in Pumpkin Yield in Response to Low-Dosage Root Zone Application of Urine-Enhanced Biochar to a Fertile Tropical Soil
2015
A widely abundant and invasive forest shrub, Eupatorium adenophorum, was pyrolyzed in a cost-efficient flame curtain kiln to produce biochar. The resulting biochar fulfilled all the requirements for premium quality, according to the European Biochar Certificate. The biochar was either applied alone or mixed with fresh cow urine (1:1 volume) to test its capacity to serve as slow release fertilizer in a pumpkin field trial in Nepal. Treatments included cow-manure compost combined with (i) urine-only; (ii) biochar-only or (iii) urine-loaded biochar. All materials were applied directly to the root zone at a biochar dry matter content of 750 kg·ha−1 before seeding. The urine-biochar treatment le…
Catalytic Activity of Char Obtained from Fast Pyrolysis in Esterification Reactions
2021
In this study different pathways for obtaining activated carbon with catalytical activity were analysed. Industrially fast pyrolysis is an efficient way of lignocellulosic biomass processing, since in this process various important high value chemicals are obtained. Biochar is obtained as the by-product in fast pyrolysis process from which activated carbon can be acquired with further chemical activation. Different methods for chemical activation of biochar were tested with the obtained activated charcoals being used as a catalyst in esterification reactions to evaluate their potential use as a heterogenic catalyst. Highest catalytical activity was observed when biochar was pre-treated with…