Showing papers on "Pyrolysis published in 1998"
TL;DR: In this paper, a nitrogen purged static-bed batch reactor was used to pyrolyse 3 kg batches of shredded scrap tyres at temperatures between 450 and 600°C. The oils were trapped in a series of condensers and the derived gases analysed off-line by packed column gas chromatography.
401 citations
TL;DR: In this paper, an analytical scheme for the characterization of biomass-based flash pyrolysis oils was developed based on fractionation of the oils with water and on further extraction of the water-soluble fraction with diethylether.
Abstract: An analytical scheme for the characterization of biomass-based flash pyrolysis oils was developed. The scheme was based on fractionation of the oils with water and on further extraction of the water-soluble fraction with diethylether. The chemical composition of the fractions was analyzed by gas chromatography–mass spectrometry. The physical and chemical nature of straw, pine and hardwood pyrolysis oils was determined and compared with each other. Correlations between the physical properties and chemical composition of the oils were drawn. The characterization method will be utilized in further work for stabilization and upgrading tests of flash pyrolysis oils.
391 citations
TL;DR: In this article, pyrolysis of acetylene over iron/silica substrates is an effective method with which to produce very long, multiwalled carbon nanotubes that reach about 2 mm in length.
Abstract: Carbon nanotubes1 can now be produced in large quantities by either arc methods2,3 or thermal decomposition of hydrocarbons4,5. Here we report that pyrolysis of acetylene over iron/silica substrates is an effective method with which to produce very long, multiwalled carbon nanotubes that reach about 2 mm in length, which is an order of magnitude longer than that described in most previous reports1,2,3,4,5,.
341 citations
TL;DR: In this paper, the authors show that carbon nanostructures such as singlewalled and multi-walled nanotubes (SWNTs and MWNTs) or graphitic polyhedral nanoparticles can be produced using various methods, such as electric arc discharge process, the laser ablation method, or the solar tech- nique.
Abstract: Carbon nanostructures such as single-walled and multi-walled nanotubes (SWNTs and MWNTs) or graphitic polyhedral nanoparticles can be produced using various methods. Most of them are based on the sublimation of carbon under an inert atmosphere, such as the electric arc discharge process, the laser ablation method, or the solar tech- nique. But chemical methods can also be used to synthesize these kinds of carbon materials: the catalytic decomposi- tion of hydrocarbons, the production by electrolysis, the heat treatment of a polymer, the low temperature solid pyrolysis, or the in situ catalysis.
323 citations
TL;DR: In this article, the cleanest fuel for power generation using fuel cells and for transportation is proposed as a clean alternative to hydrogen for both power generation and transportation, and two distinct strategies for converting biomass to hydrogen are discussed.
Abstract: Hydrogen is of great interest as the cleanest fuel for power generation using fuel cells and for transportation. Biomass can be thermochemically converted to hydrogen via two distinct strategies: ...
305 citations
TL;DR: A review of recent developments in plastics cracking, a process developed to recycle plastic wastes into useful petrochemical materials under thermal cracking conditions, can be found in this paper, where plastic wastes can be decomposed into three fractions: gas, liquid and solid residue.
Abstract: This paper reviews recent developments in plastics cracking, a process developed to recycle plastic wastes into useful petrochemical materials Under thermal cracking conditions, plastic wastes can be decomposed into three fractions: gas, liquid and solid residue The liquid products are usually composed of higher boiling point hydrocarbons By adopting customary fluid cracking catalysts and reforming catalysts, more aromatics and naphthenes in the C6 ‐C8 range can be produced, which are valuable gasoline-range hydrocarbons More tests are, however, needed to verify the pyrolysis process in a pilot scale particularly for treatment of mixtures of bulk plastics Plastics cracking is only an elementary conversion technology; its application has to be combined with other technologies such as municipal solid waste collection, classification and pretreatment at the front end, as well as hydrocarbon distillation and purification at the back end Social, environmental and economic factors are also important in industrial implementation of the technology © 1998 Elsevier Science BV All rights reserved
300 citations
TL;DR: In this paper, a combination of thermogravimetry and evolved gas analysis by Fourier transform infrared analysis (TG-FTIR) has been applied to study the influence of potassium chloride (KCl) on wheat straw pyrolysis.
Abstract: The interest in utilizing biomass as a CO2 neutral fuel by combustion, gasification, or pyrolysis processes is increasing due to concern about the emission of greenhouse gases from fossil fuel combustion. In thermal fuel conversion, pyrolysis is an important step which determines the split of products into char, tar, and gas. In this work, a combination of thermogravimetry and evolved gas analysis by Fourier transform infrared analysis (TG-FTIR) has been applied to study the influence of potassium chloride (KCl) on wheat straw pyrolysis. Raw straw, washed straw, and washed straw impregnated with KCl have been investigated. To facilitate interpretation of the results, pyrolysis of biopolymers (cellulose, xylan, lignin) in the presence and absence of KCl was investigated as well. The raw straw decomposed in a single broad featureless peak. By washing, two peaks appeared in the derivative weight loss curve, corresponding to the decomposition of hemicellulose and cellulose components in the straw. Washing red...
288 citations
TL;DR: Aligned-nanotube bundles have been obtained in copious quantities by the pyrolysis of ferrocene or Ferrocene-acetylene mixtures.
261 citations
TL;DR: In this article, a new procedure is proposed for the effective conversion of biomass flash pyrolysis liquids (BFPLs) to transportation fuels, both in a thermal and in a catalytic mode.
235 citations
TL;DR: In this article, a pyrolysis reactor consisting of a graphitized alumina tube heated to 1450 °C was used for isotope-ratio-monitoring mass spectrometric systems and yields of H2 were obtained for all components of a homologous series of n-alkanes.
Abstract: Hydrogen gas can be produced quantitatively from nanomole amounts of organic H in continuously flowing gas streams. The system described here is suitable for use in isotope-ratio-monitoring mass spectrometric systems and is based on a pyrolysis reactor consisting of a graphitized alumina tube heated to 1450 °C. Methane forms as an intermediate product at temperatures above 750 °C, but, for all tested analytes, yields of H2 were quantitative at temperatures between 1430 and 1460 °C, provided residence times in the reactor were greater than 300 ms. Quantitative yields of H2 were obtained for all components of a homologous series of n-alkanes (C15 to C30). Analyses of low-molecular-weight alcohols demonstrated that O-bound H was also quantitatively converted to H2 and, thus, that H2O, if formed, was quantitatively reduced to H2.
221 citations
TL;DR: Gas-phase pyrolysis of acetylene along with a metallocene or with a binary mixture of metallocenes in flowing Ar or Ar + H2 at 1100°C yields single-walled carbon nanotubes.
TL;DR: In this paper, the mesopore radius of carbon aerogels was found to range from 2.0 to 6.1 nm by changing the amount of resorcinol, formaldehyde, distilled water, and sodium carbonate used in polycondensation.
TL;DR: In this paper, cellobiose decomposition kinetics and products in sub- and supercritical water were studied with a flow apparatus at temperatures from 300 to 400 °C at pressures from 25 to 40 MPa, and at short residence times (0.04−2 s).
Abstract: Cellobiose decomposition kinetics and products in sub- and supercritical water were studied with a flow apparatus at temperatures from 300 to 400 °C at pressures from 25 to 40 MPa, and at short residence times (0.04−2 s). Cellobiose was found to decompose via hydrolysis of the glycosidic bond and via pyrolysis of the reducing end. Pyrolysis products were glycosylerythrose (GE) and glycosylglycolaldehyde (GG) which were confirmed by FAB-MS. Hydrolysis products were glucose, erythrose, and glycolaldehyde from cellobiose, GE, and GG, respectively, as well as glucose decomposition products. The kinetics from glucose decomposition were used to fit the experimental results and evaluate rate constants of hydrolysis (kH) and pyrolysis rate constants (k1 and k2). The activation energy for the hydrolysis of cellobiose and pyrolysis products GG and GE was found to be 108.6, 110.5, and 106.1 kJ/mol, respectively. In the supercritical region, there was a decrease in the pyrolysis rates k1 and k2 and a corresponding in...
01 Jan 1998
TL;DR: A detailed overview of analytical pyrolysis can be found in this paper, where the authors present a survey of analytical techniques used in the process and their application to organic polymers.
Abstract: Part 1: An Introduction to Analytical Pyrolysis. 1. Introduction and Nomenclature. Pyrolysis as a chemical process. The scope of analytical pyrolysis. Analytical pyrolysis applied to natural organic polymers. 2. The Chemistry of the Pyrolytic Process. General remarks. Elimination reactions in pyrolysis. Rearrangements taking place in pyrolysis. Oxidations and reductions taking place in pyrolysis. Substitutions and additions taking place in pyrolysis. Typical polymer degradations during pyrolysis. Pyrolysis in the presence of additional reactants or with catalysts. 3. Physico-Chemical Aspects of the Pyrolytic Process. Thermodynamic factors in pyrolytic chemical reactions. Kinetic factors in pyrolytic chemical reactions. Models attempting to describe the kinetics of the pyrolytic processes of solid samples. Pyrolysis kinetics for uniform repetitive polymers. Pyrolytic processes compared with combustion. Pyrolysis process compared to ion fragmentation in mass spectrometry. Theoretical approaches for chemical pyrolytic reactions. 4. Instrumentation Used for Pyrolysis. The temperature control of the pyrolytic process. Curie point pyrolysers. Resistively heated filament pyrolysers. Furnace pyrolysers. Radiative heating (laser) pyrolysers. Other pyrolyser types. Comparison of analytical performances of different pyrolyser types. 5. Analytical Techniques Used with Pyrolysis. The selection of the analytical techniques and the transfer of the pyrolysate to the analytical instrument. Pyrolysis-gas chromatography (Py-GC). Mass spectrometers as detectors in pyrolysis-gas chromatography. Pyrolysis-mass spectrometric (Py-MS) techniques. Data interpretation in pyrolysis - mass spectrometry (Py-MS). Infrared spectroscopy (IR) used as a detecting technique for pyrolysis. Other analytical techniques in pyrolysis. Part 2: Analytical Pyrolysis of Organic Biopolymers. 6. Analytical pyrolysis of polyterpenes. Natural rubber. Vulcanized rubber. Other polyterpenes. 7. Analytical Pyrolysis of Polymeric Carbohydrates. Monosaccharides, polysaccharides and general aspects of their pyrolysis. Cellulose. Chemically modified celluloses. Amylose and amylopectin. Pectins. Gums and mucilages. Hemicelluloses and other plant polysaccharides. Algal polysaccharides. Microbial polysaccharides. Lipolysaccharides from the cell surface of bacteria. Fungal polysaccharides. Glycogen. Chitin. Proteoglycans. 8. Analytical Pyrolysis of Polymeric Materials with Lipid Moieties. Classification of complex lipids and analytical pyrolysis of simple lipids. Complex lipids. 9. Analytical Pyrolysis of Lignins. Lignin. Lignocellulosic materials. Chemically modified lignins. 10. Analytical Pyrolysis of Polymeric Tannins. Polymeric tannins. 11. Analytical Pyrolysis of Caramel Colors and of Maillard Browning Polymers. Pyrolysis of caramel colors. Sugar-ammonia and sugar-amines browning polymers. Sugar-amino acid browning polymers. 12. Analytical Pyrolysis of Proteins.
TL;DR: In this article, a method is proposed by which pyrolysis rates of biomass materials can be predicted from the species compositions in terms of the basic constituents (cellulose, hemicellulose and lignin) and their individual kinetic parameters.
TL;DR: In this article, rice hulls were pyrolyzed in a thermogravimetric analyzer in a helium atmosphere to determine the kinetic parameters of devolatilization reactions.
Abstract: Rice hulls were pyrolyzed in a thermogravimetric analyzer in a helium atmosphere to determine the kinetic parameters of devolatilization reactions. The pyrolysis experiments were conducted by heating rice hulls from room temperature to 1173 K at constant heating rates of 3,10, 30, 60, and 100 K/min. The global mass loss during rice hull pyrolysis was successfully simulated by a combination of four independent parallel reactions, the decompositions of four major components in rice hulls: moisture, hemicellulose, cellulose, and lignin. The activation energy for the decomposition of the nonmoisture components was in the order cellulose > hemicellulose > lignin. It was also found in the present study that the pyrolytic behaviors were significantly influenced by water wash prior to pyrolysis. The water wash elevates the peak temperature and the activation energy for the decomposition of each component of rice hulls. The volatile yields resulting from cellulose and hemicellulose decompositions during rice hull...
TL;DR: In this paper, the effects of temperature, ZnCl2 and acid solution concentrations (during chemical washing) on the performance of pyrolysis/gasification of grape and olive bagasse by CO2 under different experimental conditions were investigated.
TL;DR: In this article, a new class of pyrolytic carbon materials has been prepared by chemical vapor infiltration of a microporous zeolite powder followed by removal of the zeolitic substrate.
Abstract: A new class of pyrolytic carbon materials has been prepared by chemical vapor infiltration of a microporous zeolite powder followed by removal of the zeolitic substrate. A wide-pore Y zeolite was used as the substrate for the pyrolytic carbon, and propylene was used as the carbon precursor. The structure and porous texture of the resulting carbons were examined by X-ray diffraction, scanning and transmission electron microscopy, and by adsorption of N2 at 77 K and CO2 at 273 K. Carbon reactivity studies were performed by both nonisothermal and isothermal thermogravimetric analysis. Under the present conditions of chemical vapor infiltration (800−850 °C, 2.5 vol % C3H6, 1 atm of N2), high-surface-area microporous carbons, with wide microporosity, well-developed mesoporosity and high adsorption capacity were obtained. The carbon yield and the apparent surface area of the carbon increased with increasing propylene pyrolysis temperature. The morphology of the carbons was very similar to that of the zeolite te...
TL;DR: In this article, tetramethylammonium hydroxide thermochemolysis was used to structurally characterize a variety of bio-and geo-polymers, which can be easily implemented in any laboratory having gas chromatographic capabilities.
TL;DR: In this paper, an ultra-pycnometer and a mercury intrusion porosimeter were used to measure the solid and apparent densities of the samples, respectively and a thermogravimetric analyzer was used for proximate analysis.
TL;DR: In this article, carbon film electrodes were prepared by pyrolysis of photoresists on silicon wafers at temperatures ranging from 600 to 1,100 C. The physical properties of the carbon films were characterized by scanning and transmission electron microscopies, thermal gravimetric analysis, and four-point probe electrical resistivity measurements.
Abstract: Carbon film electrodes were prepared by pyrolysis of photoresists on silicon wafers at temperatures ranging from 600 to 1,100 C. The physical properties of the carbon films were characterized by scanning and transmission electron microscopies, thermal gravimetric analysis, and four-point probe electrical resistivity measurements. The electrochemical properties of the carbon films were investigated by cyclic voltammetry to observe the kinetics of the Fe(CN){sub 6}{sup 4{minus}}/Fe(CN){sub 6}{sup 3{minus}} redox couple. The carbon film electrodes prepared at temperatures {ge} 700 C showed electrochemical behavior similar to that of glassy carbon. Better electrocatalytic behavior was obtained with carbon films prepared at the higher pyrolysis temperatures, which is attributed to different film compositions at different pyrolysis temperatures. The electrochemical properties of the carbon film electrodes are very stable, exhibiting reproducible behavior even after storing at room temperature in air for 3 months.
TL;DR: In this paper, different quantities of iron tetraphenylporphyrin (FeTPP) have been adsorbed onto carbon black (XC) and pyrolyzed at 1000 degrees C to produce catalysts containing iron loadings of 2, 4 and 6 wt%.
TL;DR: In this paper, the role of N 2, O 2, CO 2 and H 2 O gases in the activation of wood by phosphoric acid was analyzed. But the authors did not consider the effect of other gases.
TL;DR: In this article, the feasibility of preparing activated carbons from extracted oil palm fibre, an abundant oil palm waste, was studied, and preliminary tests were conducted to investigate the influences of different operating parameters, such as initial material size, inert gas flow rate, heating rate, pyrolysis temperature and hold time, on the properties of pyrolysed chars.
TL;DR: In this paper, a stepwise pyrolysis procedure where the thermal decomposition of different components of a mixture of poly(vinyl chloride) is performed consecutively at different temperatures is presented.
TL;DR: In this article, the carbon isotopic composition of the Murchison meteorite was determined by gas chromatography-isotope ratio-mass spectrometry (GCIRMS), and the organic fragments of the macromolecular material were consistently 13 C-enriched when compared to structurally identical free molecules.
TL;DR: In this paper, thermal loss occurs in three stages, centered around 250°C, 350°C and 550°C producing high quantities of gases, as hydrogen, water, hydrocarbons (C1−C4, both saturated and unsaturated), methanol, chloromethane, carbon dioxide and acetic acid.
TL;DR: In this article, the molecular mechanisms by which dissolved organic matter (DOM) forms and soil organic matter degrades in upland peaty gley soil under grass were investigated.
Abstract: Summary
We have sought to understand the molecular mechanisms by which dissolved organic matter (DOM) forms and soil organic matter (SOM) degrades in upland peaty gley soil under grass. Pyrolysis mass spectrometry (Py-MS) and pyrolysis gas chromatography mass spectrometry (Py-GC/MS) were applied to characterize the DOM collected from lysimeters and its parent SOM. The macromolecular organic matter in the litter and fermentation (Lf) horizon of the soil consists primarily of little decomposed lignocellulose from grass, whereas the humus (Oh) horizon is characterized by an accumulation of selectively decomposed lignocellulose material, microbial metabolites and bound fatty acids. The mineral horizon produced a relative enrichment of furan structures derived from microbial reworking of plant polysaccharides but virtually no lignin signals. A series of exceptional long chain C43 to C53 fatty acids with odd over even predominance, probably derived from mycobacteria, were also identified in the Oh horizon. Side-chain oxidation and shortening, increase of carboxyl functionality and selective removal of syringyl (S) > guaiacyl (G) > p-hydroxyphenyl (P) lignin units were the main reactions when lignin degraded. Compared with SOM, the DOM shows a large accumulation of more oxidized lignin and aromatic structures, especially those containing carboxylic and dicarboxylic acid functionalities and with shorter side-chain length. The polysaccharide-type compounds in the DOM were more modified (greater abundance of furan structures in pyrolysis products), and had significantly lower molecular weight and more diverse polymeric structures than did those in soils. Increased temperature and rainfall appeared to result in greater relative abundance of lignin degradation products and aromatic compounds in DOM.
TL;DR: Fe-based catalysts for the reduction of oxygen in polymer electrolyte fuel cells (PEFCs) have been prepared from a precursor containing 10 wt% Fe as-Fe(OH)(2) adsorbed on carbon black (Fe(O)(2)/C) Activation of the precursor was performed in two steps: (i) H 2 reduction at 600 degrees C; (ii) pyrolysis in acetonitrile (AN) vapor at various temperatures (400, 600, 800, 1000 degrees C).
TL;DR: In this article, a theory according with the various relevant literature is proposed for the interaction among the components, advocating that post-fusion pore-growth sustains the interaction between components that, in turn, influences the adsorption characteristics of biomass.