Showing papers on "Pyrolysis published in 1984"
TL;DR: In this paper, the relative importance of internal and external heat transfer and of the intrinsic (first order) pyrolysis kinetics can be determined from the Biot number (hR/K).
358 citations
TL;DR: Aromaticities determined by 13 C n.m.r. as discussed by the authors for five shale oil samples (Green River formation) prepared under widely different pyrolysis conditions.
301 citations
TL;DR: In this article, a continuous atmospheric pressure flash pyrolysis process for the production of organic liquids from cellulosic biomass has been demonstrated at a scale of 1-3 kg/hr of dry feed.
Abstract: A continuous atmospheric pressure flash pyrolysis process for the production of organic liquids from cellulosic biomass has been demonstrated at a scale of 1–3 kg/hr of dry feed. Organic liquid yields as high as 65–70% of the dry feed can be obtained from hardwood waste material, and 45–50% from wheat straw. The fluidized sand bed pyrolysis reactor operates on a unique principle so that char does not accumulate in the bed and treatment of the sand is not necessary. The product gas, about 15% of the yield, has a medium heating value. The liquid product is an acidic fluid, which pours easily and appears to be stable. A preliminary economic analysis suggests that if the pyrolysis oil can be used directly as a fuel, its production cost from wood waste is probably competitive with conventional fuel oil at the present time.
265 citations
TL;DR: In this paper, the Messel shale was subjected to pyrolysis at 330°C for 3 days in the presence of excess water or heavy water and also with added pure organic substances.
215 citations
TL;DR: Fast pyrolysis is defined and related to other biomass thermochemical conversion processes in some detail in this article, where proposed mechanisms and chemical pathways are reviewed, potential products are identified and product upgrading and product applications are identified.
187 citations
TL;DR: In this article, the interaction between pure clay minerals and the hydrocarbons coming from the cracking of an organic matter of marine origin (type II) was investigated under pyrolysis conditions of the Rock-Eval type.
177 citations
TL;DR: In this paper, it was shown that the pyrolysis reactions of hard coal may be interpreted in terms of parallel first-order reactions relating to the coal functional groups which can be considered as predecessors of the coal products, and the activation energies measured are of the same order of magnitude as the bonding energies of bridge CC bonds between the aromatic ring-systems in coal molecule.
159 citations
TL;DR: In this paper, it has been shown that (NH4)2HPO4, which is a well-known flame retardant and smoldering inhibitor, lowers the pyrolysis temperature and increases the char yield by accelerating the decomposition reactions.
Abstract: At temperature above 300°C the glycosyl units of cellulose are simultaneously depolymerized to a tar and decomposed to a char by evolution of H2O, CO, and CO2. When the glycosyl units are depleted, a stable char is formed containing about 30% aliphatic and 70% aromatic components. The aliphatic component is formed first, but on further heating is converted to polycyclic aromatic structures. The chars formed at lower temperatures are more combustible because the aliphatic component of the char is highly pyrophoric and is oxidized almost at the same temperature at which it is formed (∼360°C). The aromatic component, however, is less reactive and is oxidized at ∼520°C. Consequently, the chars formed at higher temperatures are less combustible. It has been shown that (NH4)2HPO4, which is a well-known flame retardant and smoldering inhibitor, lowers the pyrolysis temperature and increases the char yield by accelerating the decomposition reactions. This affects the composition of the intermediate chars but the final products have about the same composition irrespective of additives. (NH4)2HPO4 also lowers the rate of oxidation of the aromatic component and the corresponding heat release. NaCl, which is an enhancer of smoldering combustion, has a slight stabilizing effect on pyrolysis of cellulose. It lowers the oxidation temperature of the aromatic component and dramatically increases its rate. The corresponding heat release is also increased due to complete oxidation to CO2. The rate of oxidation calculated from the dynamic thermal analysis data is more than tripled by NaCl and significantly reduced by (NH4)2HPO4.
149 citations
TL;DR: In this article, a pyrolysis unit was developed to study effects of temperature, heating rate, wood particle size, moisture, gaseous environment, and catalyst impregnation.
Abstract: A pyrolysis unit was developed to study effects of temperature, heating rate, wood particle size, moisture, gaseous environment, and catalyst impregnation on the wood pyrolysis. Effects of these parameters on char, oil, and gas yields and composition are presented and interpreted to assist the industrial use of the wood-pyrolysis technology.
146 citations
Journal Article•
TL;DR: Differential thermal analysis of milled wood Lignin and lignin carbohydrate complex at different heating rates showed three exothermic peaks as discussed by the authors, and the heating rate is the factor that affects their sharpness and position.
Abstract: Differential thermal analysis studies of milled wood lignin and lignin carbohydrate complex at different heating rates showed three exothermic peaks. The heating rate is the factor that affects their sharpness and position. The peaks are sharp at low heating rates. Infrared spectra and scanning electron micrographs of the pyrolyzed lignin residues show that aliphatic scission of the lignin molecule at the onset of pyrolysis and progressive carbonization of the surface are the principal features of degradation; there is no intermediate compound formed during the pyrolysis.
101 citations
TL;DR: In this paper, the molecular weight distributions of tars produced during flash pyrolysis of coal have been determined by a combination of gel permeation chromatography and vapour phase osmometry.
TL;DR: In this paper, the use of alkaline catalysts under liquefaction at 300 C was shown to shift the mechanism from one involving aqueous pyrolysis (predominant furan formation) to one incorporating aldol and related condensations.
Abstract: Direct thermochemical conversion of cellulosic biomass to useful products has been studied as an alternative to conventional biological processes. At temperatures of 250-400 C and pressures up to 20.7 MPa in the presence of sodium carbonate, pure cellulose was converted to a mixture of phenols, cyclopentanones, and hydroquinones as well as other components. This liquefaction oil and others were examined for their use as fuel asphalt substitutes and wood adhesives. The product composition tended to change with liquefaction time. One major product of cellulose liquefaction, 2,5-dimethyl-1,4-benzenediol, was formed during a reduction-oxidation procedure involving acetoin and biacetyl. The use of alkaline catalysts under liquefaction at 300 C was shown to shift the mechanism from one involving aqueous pyrolysis (predominant furan formation) to one incorporating aldol and related condensations. 33 references, 1 figure, 4 tables.
TL;DR: A quantitative relationship between amino acid composition and pyrrole and acetonitrile abundances has been established by Curie-point pyrolysis-gas chromatography of a group of test proteins, using polystyrene as an internal standard as discussed by the authors.
TL;DR: In this article, the product yields from cracking coal tar in a fixed-bed reactor were determined at various temperatures in the presence and absence of various packing materials, and the results showed that Linde zeolite LZ-Y82 was very effective in converting coal tar to chars and gases in the temperature range 400-500 C. Among the factors involved for catalytic effectiveness are: an effective pore size > 0.7 nm, a large internal surface accessible to the tar vapor; and a large number of strongly acidic sites.
Abstract: The product yields from cracking a bituminous coal tar in a fixed-bed reactor were determined at various temperatures in the presence and absence of various packing materials. Some synthetic and natural zeolites showed strong catalytic activity, but those with small pore diameters were much less active. Linde zeolite LZ-Y82 was very effective in converting tar to chars and gases in the temperature range 400-500 C. Among the factors involved for catalytic effectiveness are: an effective pore size >0.7 nm; a large internal surface accessible to the tar vapor; and a large number of strongly acidic sites.
TL;DR: In this article, steam was introduced at the top of a pressurized reactor containing mixed southern hardwood chips while steam condensate and partible products were removed at the bottom of the reactor.
Abstract: Rapid steam hydrolysis of wood chips with continuous condensate/product removal was investigated as a biomass pretreatment similar to steam explosion. Steam was introduced at the top of a pressurized reactor containing mixed southern hardwood chips while steam condensate and partible products were removed at the bottom of the reactor. A reaction time of one minute was employed for isothermal steaming runs from 160-280°C. Fractionation of wood occurred at temperatures above 200°C as hemicellulose and lignin began to appear in the steam condensate fraction, leaving a cellulose-rich fraction in the steaming reactor. At high temperatures cellulose was not degraded as much as it was in steam explosion at the same temperature, presumably due to the removal of acetic acid as it is formed. Lignin extracted from the solid residue appeared particularly reactive as determined by nitrobenzene oxidation and pyrolysis/gas chromatography. Lignin collected in the steam condensate was also very reactive, presumab...
Patent•
17 Dec 1984TL;DR: In this paper, a method of preparing carbon-containing monolithic glassy ceramics from organosilsesquioxanes, metal oxides and metal alkoxides through pyrolysis of their gels is presented.
Abstract: What is disclosed is a method of preparing carbon-containing monolithic glassy ceramics from organosilsesquioxanes, metal oxides and metal alkoxides through pyrolysis of their gels. Also disclosed are certain gel compositions used in the method and the glassy ceramics.
TL;DR: In this article, a comparative study of the relative catalytic effects of potassium and calcium on the gasification in air and 3.1 kPa steam of North Dakota lignitic chars prepared under slow and rapid pyrolysis conditions is made.
TL;DR: The state of the art in pyrolysis mass spectrometry techniques is illustrated through specific applications, including structural determination and quality control of synthetic polymers, quantitative analysis of polymer mixtures, classification and structural characterization of fossil organic matter, and nonsupervised numerical extraction of component patterns from complex biological samples.
Abstract: Pyrolysis mass spectrometry in combination with computerized multivariate statistical analysis enables qualitative and quantitative analysis of nonvolatile organic materials containing molecular assemblies of a complexity and size far beyond the capabilities of direct mass spectrometry The state of the art in pyrolysis mass spectrometry techniques is illustrated through specific applications, including structural determination and quality control of synthetic polymers, quantitative analysis of polymer mixtures, classification and structural characterization of fossil organic matter, and nonsupervised numerical extraction of component patterns from complex biological samples
TL;DR: Using the derivative thermogravimetric technique, an investigation was made of the pyrolysis and oxidation of some heavy fuel oils and their separate paraffinic, aromatic, polar and asphaltene fractions as mentioned in this paper.
TL;DR: In this article, a theory has been developed that combines random cleavage of weak bonds in the polymer (to produce metaplast) with transport of depolymerization fragments by vaporization and diffusion, and theoretical predictions for various temperatures, heating rates and pressures compare favourably with tar yields measured in a heated grid apparatus and molecular weight distribution determined by field ionization mass spectrometry.
TL;DR: In this article, the results of measurements of the optical absorption spectra of polyacrilonitrile are presented as a function of the pyrolysis temperature Tp and of the duration of pyrolyses.
Abstract: The results of measurements of the optical absorption spectra, IR absorption spectra, thermogravimetric analysis, and elementary analysis of pyrolyzed polyacrilonitrile are presented as a function of the pyrolysis temperature Tp and of the duration of pyrolysis. At Tp ∼ 200°C, an intermediate phase was discovered, containing conjugated CN sequences and a completely unreacted carbon backbone. The optical absorption data imply that the resulting polymer is a semiconductor with a delocalized π-electron system and an energy gap Eg ⋍ 2.5 eV. For Tp > 260°C, the weight loss rapidly increases, and the absorption edge gradually broadens and shifts to lower energies. The resulting polymer (after higher-temperature pyrolysis) contains CN and CCC conjugation sequences, but appears to be a complex structure consisting of a mixture of different chemical species.
TL;DR: In this article, the authors investigated the devolatilisation behavior of Yallourn brown coal under rapid heating conditions using two different flash pyrolysers: a fluid-bed reactor giving coal particle heating rates of 104 °C−1 with a gas residence time of about 0.5 s and a shock tube which generated heating rates in the order of 107 °Cs−1 and a 1 ms reaction time.
TL;DR: In this paper, the principles and methods of soft ionization mass spectrometry in combination with pyrolysis of macromolecules are outlined, and the results of flash pyroplysis by Curie-point heating and thermally programmed degradation of biopolymers are compared.
Journal Article•
TL;DR: In this paper, the authors present a mathematical model that is used to calculate accurately the oil yield for any arbitrary pyrolysis conditions for Green River oil shale, but it could be easily modified for other oil shales.
Abstract: The authors present a mathematical model that is used to calculate accurately the oil yield for any arbitrary pyrolysis conditions. As presently formulated, it is valid only for Green River oil shale, but it could be easily modified for other oil shales. A central feature of this model is that it divides the oil into 11 boiling-point fractions in order to treat evaporation more rigorously. This feature also allows cracking of heavy fractions to lighter fractions, enabling a calculation of the effect of pyrolysis conditions on the boiling-point distribution of the product oil. The model is tested under a wide range of pyrolysis conditions for which data are available in the literature.
TL;DR: In this paper, it was shown that a thin film of sputtered iron, formed by thermal decomposition of a solution of ferric nitrate in the presence of mercury vapour, with subsequent reduction of the oxide, was found to induce formation of filamentous carbon during the pyrolysis of methane.
Patent•
30 Mar 1984
TL;DR: In this paper, a zeolitic cracking catalyst containing a significant concentration of a calcium-containing additive as a vanadium passivating agent was used to convert hydrogen containing vanadium to lower boiling fractions.
Abstract: Hydrocarbons containing vanadium are converted to lower boiling fractions employing a zeolitic cracking catalyst containing a significant concentration of a calcium-containing additive as a vanadium passivating agent.
TL;DR: In this article, the authors discuss possible mechanisms for the pyrolytic reaction of biomass with steam in the presence of alkali carbonate and supported-nickel catalysts.
TL;DR: In this paper, the radiant flash pyrolysis of Avicel cellulose and kraft paper particles using concentrated visible light is described, where particles circulate in a clear quartz spouted bed reactor while undergoing pyroolysis in an incident radiant flux of up to 200 W/cm2.