Showing papers on "Pyrolysis published in 1981"

Kinetic investigation of wood pyrolysis

Abstract: The kinetics of wood pyrolysis into gas, tar, and char was investigated in the range of 300 to 400 degrees Celcius at atmospheric pressure. An experimental system which facilitates the monitoring of the actual sample temperature, collection of gas and tar, and measurement of the sample weight loss as a function of time was developed. It has been found that, in the range investigated, wood decomposition into gas, tar, and char can be described by three parallel first-order reactions as suggested by Shafizadeh and Chin (1977). The activation energies for these reactions are 88.6, 112.7 and 106.5 kJ/mol, respectively, and their frequency factors defined on a mass basis are 8.61 x 10 to the power of 5, 2.47 x 10 to the power of 8, and 4.43 x 10 to the power of 7 min-1. The composition of the pyrolysis products was also analyzed. It was found that the gas consists mainly of carbon dioxide, carbon monoxide, oxygen, and C3 + compounds with trace amounts of methane, ethylene, and acetylene. The tar consists of seven compounds with levoglucosan accounting for more than half. The char was analyzed by elemental analysis and it was found that its carbon content increases withmore » increasing reactor temperature. (Refs. 12).« less

Pyrolysis of bacterial polyalkanoates

Abstract: Pyrolysis products from bacterial polyesters, poly-β-hydroxybutyrate (PHB), and from a heteropolyester (β-hydroxyvalerate and β-hydroxybutyrate) were identified. Different physical forms of PHB wer...

Carbon-reinforced metal-matrix composites

Abstract: A carbon fiber reinforced metal matrix composite is produced by metal oxide coating the surface of the fibers by passing the fibers through an organometallic solution followed by pyrolysis or hydrolysis of the organometallic compounds. The metal oxide coated fibers so produced are readily wettable without degradation when immersed in a molten bath of the metal matrix material.

Combustion and pyrolysis of poly(ethylene terephthalate). I. The role of flame retardants on products of pyrolysis

Abstract: The products of pyrolysis of untreated and flame-retarded poly(ethylene terephthalate) (PET) have been studied at two temperatures using a flash pyrolysis/gas chromatography technique. The pyrolysis products were identified by gas chromatography/mass spectrometry and reaction mechanism for their formation are proposed. A quantitative and qualitative analysis of these products reveals that the phosphorus-only flame retardants have no effect on the solid-phase pyrolysis of PET. The two bromine-containing flame retardants, however, while capable of influencing the pyrolysis, were not capable of producing large changes in the major products. Their main role in the pyrolysis appears to alter slightly the balance of several competing secondary pyrolysis reactions.

Immobilization of vanadia deposited on catalytic materials during carbo-metallic oil conversion

Abstract: A process is disclosed for the conversion of a hydrocarbon oil feed having a significant content of vanadium to lighter oil products by contacting the feed under conversion conditions in a conversion zone with a catalyst containing a metal additive to immobilize vanadium compounds. Conversion conditions are such that coke and vanadium are deposited on the catalyst in the conversion zone. Coked catalyst is regenerated in the presence of an oxygen containing gas at a temperature sufficient to remove the coke and regenerated catalyst is recycled to the conversion zone for contact with fresh feed. The metal additive is present on the catalyst in an amount sufficient to immobilize the vanadium compounds in the presence of oxygen containing gas at the catalyst regeneration temperature. A catalyst composition comprises a crystalline alumino-silicate zeolite dispersed in an amorphous inert solid matrix containing the metal additive, which may be introduced into the catalyst during the conversion process or during catalyst manufacture. Metal additives include water soluble inorganic metal salts and hydrocarbon soluble inorganic metal salts and hydrocarbon soluble organometallic compounds of select metals.

Pyrolyzed pitch coatings for carbon fiber

Abstract: Carbon fibers in a carbon-fiber-reinforced metal-matrix composite having a relatively very high modulus are treated with a relatively thin amorphous carbon coating precedent to a metal-oxide film to improve the adhesion thereof to the carbon fiber thereby facilitating the wetting of carbon fibers to molten matrix metal.

Effects of calcium minerals on the rapid pyrolysis of a bituminous coal

Abstract: This paper presents results on the pretreatment of coal with calcite (CaCO/sub 3/) and lime (CaO). These minerals have already been shown to influence fluidized-bed pyrolysis, steam gasification, and CO/sub 2/ gasification of coal. Addition of CaCO/sub 3/ or CaO to coal reduces the high temperature yield of hydrocarbon products and increases the yield of CO in rapid coal pyrolysis. The former effect is probably attributable to lime-catalyzed secondary cracking reactions, while the latter results from base catalysis of a step in the decomposition of the phenolic groups. Calcite in the presence of coal decomposes to lime and CO/sub 2/ at lower temperatures than it will when pyrolyzed alone.

Endothermic removal of coke deposited on sorbent materials during carbo-metallic oil conversion

Abstract: A process is disclosed for the conversion of high boiling oil feeds having a significant level of Conradson carbon components and metals to form lighter oil products by contacting the feed under catalytic conversion conditions with a catalyst containing one of a select group of metal additives to catalyze the endothermic removal of carbon with CO2. Conversion conditions are such that hydrocarbonaceous material and metals are deposited to deactivate the catalyst in the conversion zone. Deactivated catalyst is partially regenerated in the presence of carbon dioxide containing gas before or after oxygen regeneration at a temperature below 1600° F. to provide a regenerated catalyst which is recycled to the conversion zone for further contact with fresh feed. The metal additive is present on the catalyst in an amount sufficient to catalyze the endothermic removal of carbonaceous material in the presence of a carbon dioxide rich gas at regeneration temperature below 1500° F. The catalyst composition comprises a crystalline alumino-silicate dispersed in a solid matrix material and containing one or more of the metal additives. Metal additive may be introduced into the catalyst during the conversion process or during catalyst manufacture. Metal additives include water soluble inorganic metal salts, hydrocarbon soluble organo-metallic compounds of the select group of metals, and metal contaminants found in a high boiling residual oil feed.

Model pathways in lignin thermolysis

Abstract: Thesis (ScD)--Massachusetts Institute of Technology, Dept of Chemical Engineering, 1981

Preparation and modification of complex pyrolytic carbon-silica adsorbents

Abstract: The surface properties of complex adsorbents prepared through the pyrolysis of dichloromethane on the surface of silica gel were investigated. The reaction was carried out in a specially constructed reactor at 400–500°C. The construction and performance of the reactor are described. The modification of the silica gel surface by pyrogenic carbon results in its chemical but not energetical homogeneity. Such adsorbents usually show strong adsorptive properties which limits their use in chromatography. A simple method of homogenizing the porous structure and energetic properties of the adsorptive centers of such adsorbents is presented. The method consists of an additional pyrolysis of an alcohol or other substances on the surface of the carbon-silica adsorbent. Such reactions were carried out under both static and dynamic conditions. The properties of the modified adsorbent depend on the reaction conditions and on the type of the additionally pyrolysed substance.

Polymers with improved flammability characteristics. I. Phenolphthalein‐related homopolymers

Abstract: Improved fire resistance occurs for phenolphthalein-related polycarbonates and polyesters compared to bisphenol-A polymers and emphasizes the importance of polymer composition and polymer structure in affecting the flammability of a polymer. Phenolphthalein-related polymers are able to produce a higher degree of crosslinking during pyrolysis which subsequently leads to higher char yields. The correlations between oxygen index and char yield for various polymers are obtained and discussed. Polycarbonates and polyamides usually show higher oxygen indices than the corresponding polyesters of related structures. This indicates that the nature of the pyrolysis products has a measurable effect on the flammability of a specific polymer. Among many factors, polycarbonates should release more CO2 from the breakdown of the carbonate group, and polyamides should produce relatively nonflammable nitrogen-containing products during pyrolysis, thus accounting in part for these results.

Flammability resistance synergism in BPA polycarbonate–silicone block polymers

Abstract: The synergism in limiting oxygen index found in BPA carbonate–dimethylsiloxane block polymers (BPAC/DMS) is correlated with a rise in yield of pyrolytic char and an improvement in char oxidation resistance. These changes in turn are related to a peaking of fractional silicon retention in the char at a resin composition of 50 mole % DMS. This behavior, the fine dispersion of silicon in the char, and analyses of the pyrolysates suggest that an important feature of char formation in the block polymers is a polycondensation reaction between pyrolysis products from the two blocks. In addition to the role of chars in withholding fuel from the flame, they are thought to function effectively as thermal insulators.

Solar coal gasification reactor with pyrolysis gas recycle

Abstract: Coal (or other carbonaceous matter, such as biomass) is converted into a duct gas that is substantially free from hydrocarbons. The coal is fed into a solar reactor (10), and solar energy (20) is directed into the reactor onto coal char, creating a gasification front (16) and a pyrolysis front (12). A gasification zone (32) is produced well above the coal level within the reactor. A pyrolysis zone (34) is produced immediately above the coal level. Steam (18), injected into the reactor adjacent to the gasification zone (32), reacts with char to generate product gases. Solar energy supplies the energy for the endothermic steam-char reaction. The hot product gases (38) flow from the gasification zone (32) to the pyrolysis zone (34) to generate hot char. Gases (38) are withdrawn from the pyrolysis zone (34) and reinjected into the region of the reactor adjacent the gasification zone (32). This eliminates hydrocarbons in the gas by steam reformation on the hot char. The product gas (14) is withdrawn from a region of the reactor between the gasification zone (32) and the pyrolysis zone (34). The product gas will be free of tar and other hydrocarbons, and thus be suitable for use in many processes.

Steam cracking of hydrocarbons. 5. Effect of thiophene on reaction kinetics and coking

Abstract: The effect of thiophene on the kinetics and selectivity of the conversion of hydrocarbons by steam cracking was studied in a stainless steel tubular reactor with relatively large inner surface. Heptane was selected as a model and decomposed at 700 OC and 100 kPa with a mass ratio of steam to feed of 3:l. The rate of decomposition increased about 14% if 0.1 and 0.5% mass of thiophene was added, but was unchanged if 1 % was present. The influence of thiophene on the selectivity of the conversion of heptane to ethene appeared to depend on the residence time. The effect of thiophene on the formation of coke was investigated in the pyrolysis of a reformer raffinate in a stainless steel flow reactor at 820 OC, without steam. Coking is lessened with increasing amounts of thiophene in the feed (0.05-0.5 % mass). Reaction mechanisms are suggested.

Stripping hydrocarbons from catalyst with combustion gases

Abstract: A process for economically converting carbo-metallic oils to lighter products. The carbo-metallic oils contain 650° F. and material which is characterized by a carbon residue on pyrolysis of at least about 1 and a Nickel Equivalents of heavy metals content of at least about 4 parts per million. This process comprises flowing the carbo-metallic oil together with particulate cracking catalyst through a progressive flow type reactor having an elongated reaction chamber, which is at least in part vertical or inclined, for a predetermined vapor riser residence time in the range of about 0.5 to about 10 seconds, at a temperature of about 900° to about 1400° F., and under a pressure of about 10 to about 50 pounds per square inch absolute sufficient for causing a conversion per pass in the range of about 50% to 90% while producing coke in amounts in the range of about 6 to about 14% by weight based on fresh feed, and laying down coke on the catalyst in amounts in the range of about 0.3 to about 3% by weight. The spent, coke-laden catalyst from the stream of hydrocarbons formed by vaporized feed and resultant cracking products is separated, the sorbed hydrocarbons are stripped from the catalyst particles by contacting them in one or more fluidized beds with hot combustion gases. The stripped catalyst is regenerated in one or more regeneration beds in one or more regeneration zones by burning the coke on the spent catalyst with oxygen. The catalyst particles are retained in the regeneration zone or zones in contact with the combustion-supporting gas for an average total residence time in said zone or zones of about 5 to about 30 minutes to reduce the level of carbon on the catalyst to about 0.25% by weight or less. The regenerated catalyst is recycled to the reactor and contacted with fresh carbo-metallic oil.

Method and system for disposing pyrolysis gas

Abstract: A method and a system for disposing of the pyrolysis gas generated in a pyrolyzing system to refine the same are presented in which an absorbing agent for eliminating harmful gas is introduced into a thermal reactor in such an amount that a large percent of such agent is unreacted but it is efficiently recovered together with char from the pyrolysis gas and also these recovered materials are utilized to remove oil and tar from water used in cleaning the pyrolysis gas, the recovered solid particles of the char and unreacted absorbing agent and the oil and tar separated from the cleaning water being recirculated in the pyrolyzing system.

Combustion of pyrolyzed carbon containing solids in staged turbulent bed

Abstract: Process for burning a pyrolyzed carbon containing solid in a staged turbulent bed to provide hot heat transfer material for use in pyrolyzing additional carbon containing solids.

Fluid jet seed particle generator for silane pyrolysis reactor

Abstract: Method is provided for generating fine sized seed particles of silicon for use in the fluidized bed pyrolysis of silane.

Passivation of contaminant metals on cracking catalysts by phosphorus addition

Abstract: High gas and coke make due to contamination of a zeolitic fluid cracking catalyst by metal species such as nickel and vanadium during a cracking process is reduced by adding a phosphorus compound to the process. When the catalyst already contains a metals passivating agent or such agents are used in the cracking process further significant reduction in gas and coke make is realized without significant increase in regenerator temperature by adding additional phosphorus.