Showing papers on "Pyrolysis published in 1980"

Role of mineral matrix in kerogen pyrolysis; influence on petroleum generation and migration

Abstract: Comparable pyrolysis experiments have been performed on rocks containing organic matter and on related kerogens which were separated from the rock by acid treatment. In some examples, hydrocarbon yields from the rocks are lower. The experimental procedure separates the lighter hydrocarbons (lower than C15) from total hydrocarbons, thus showing that the decreased hydrocarbon yield from rocks as compared to kerogen is principally due to retention of the heaviest hydrocarbons. The light hydrocarbons do not seem to be reduced in quantity. By studying mixtures of kerogens with various minerals, we infer that retention of heavy hydrocarbon products issued from the kerogen pyrolysis occurs on the mineral surfaces. With increasing temperature and time, the trapped hydrocarbons may be cracked: light hydrocarbons are released, whereas a carbon residue remains on minerals. Some of the argillaceous minerals used (illite from Le Puy, France) are particularly active whereas other minerals such as carbonates show weak activity. Pyrolysis performed on many samples of rocks confirms these experimental assays and shows that hydrocarbon retention during pyrolysis increases with the clay content of rocks. In rocks with a low organic carbon content, these phenomena can affect the quantity of heavy hydrocarbons liberated during pyrolysis whereas the lightest hydrocarbons are little affected. Thus, under comparable geologic conditions, certain types of source rocks would release light oil and gas.

Method of in-situ retorting of carbonaceous material for recovery of organic liquids and gases

Abstract: The method of the present invention involves a two-phase process for in-situ retorting and recovery of carbonaceous material contained within typical subterranean tar sand formations, and includes formation of conventional arrays of in-seam ducts, and positioning heating devices to heat a section of the formation over a large extent thereof. The operation of the heating devices in the first phase is controlled to provide heat into the formation without burning of the carbonaceous material therein, resulting in development of a quasi-stable zone of pyrolysis about the heating duct, to thermally crack the carbonaceous material producing various organic liquid oil fractions and derived condensible vapors and non-condensible gases. The products produced thereby are then withdrawn through a suitable array of collection wells. In the second phase of the process a residual coke layer that will have formed as a result of the pyrolysis of the carbonaceous material is burned by introducing a combustion-supporting gas, such as air or oxygen, into the hot sand-coke blanket preferrably via the line source heating ducts spontaneously igniting the coke to produce a temperature elevation in the zone of pyrolysis to both crack the proximate carbonaceous material and to burn away the coke layer from around the shut-in collection wells freeing them to continue withdrawal of the products of the cracking process. After combustion of the basal sand-coke blanket air flow to the tar sand formation will be terminated and the heater operation restored, repeating the process.

Kinetics of Cellulose Pyrolysis in Nitrogen and Steam

Abstract: Kinetics of cellulose pyrolysis in nitrogen and steam at five different heating rates are presented. A single rate equation for each pyrolysis medium is discussed which provides a good engineering fit to the weight loss curves. The presence of steam in the pyrolysis medium was found to have no measurable affect on cellulose pyrolysis kinetics. The activation energy, pre-exponential factor and reaction order for nitrogen and 1 steam pyrolysis of cellulose are: 36.6 kcal/mol, 6.06 × 109sec-1, 0.46 and 34.2 kcal/mol, 1.67 / 109 sec-1, 0.51 respectively. Apparent differences in the data derived using steam rather than nitrogen as a pyrolysis medium are shown to be artifacts of heat transfer phenomenon within the TGA instrumentation used to measure rate of weight loss. Heat transfer effects observed here may explain the large discrepancies in previously reported studies of cellulose pyrolysis kinetics. Kinetic data given for steam pyrolysis are believed to be more accurate due to the more accurate mea...

High-resolution gas chromatography of the 22 tetrachlorodibenzo-p-dioxin isomers.

Abstract: The 22 tetrachlorodibenzo-p-dioxins (TCDDs) were synthesized in microgram quantities by a simple pyrolysis procedure from different potassium chlorophenates. The separation of these TCDD isomers was studied on high-resolution glass capillary columns with different stationary phases (Silar 10c, OV-17, OV-101) and using mass spectrometric detection. Conditions were found that allowed the unambiguous assignment of many of these isomers, including the very toxic 2378-TCDD. The determination of the various TCDD isomers is illustrated in the analysis of samples from known contaminated areas in Seveso, Italy and in eastern Missouri, and the method is also applied to the analysis of fish from the Tittabawassee river in Michigan and fly ash samples from municipal incinerators in Switzerland.

Intraparticle mass transfer in coal pyrolysis

Abstract: Intraparticle mass transfer in coal pyrolysis is described by ternary diffusion and viscous flow, in conjunction with a simple pore model to predict concentration profiles for gases and tar. At low pressures, product yields depend on particle size only, while at high pressures they depend on pressure and particle size. Limited experimental data from a subbituminous coal confirm these trends. Data from a bituminous coal show different trends, as expected from the drastic changes the pore structure undergoes during pyrolysis.

Mechanism of thermal degradation of polyurethanes investigated by direct pyrolysis in the mass spectrometer

Abstract: Direct pyrolysis in the mass spectrometer (MS) yielded unequivocal evidence regarding the mechanism of thermal decomposition of N-monosubstituted and N-disubstituted polyurethanes. It was ascertained that direct pyrolysis in the MS detects the primary thermal fragments that originate from polyurethane pyrolysis. This is particularly useful when, as in the thermal decomposition illustrated in eq. (1), it is necessary to distinguish between primary and secondary thermal fragments in order to assess the thermal degradation mechanism. Our results indicate that N-monosubstituted polyurethane V undergoes a quantitative depolycondensation process. Instead, the thermal decomposition of the N-disubstituted polyurethane VI which occurs selectively in eq. (1) is demonstrated by the detection of thermal fragments that contain secondary amine and olefinic end groups. Finally, polyurethane VI shows a higher thermal stability with respect to polymer V because of the absence of the depolycondensation process, which accounts for the thermal degradation of the N-monosubstituted polyurethane V.

The formation of volatile pyrolyzates form poly(vinyl chloride)

Abstract: The formation of volatile pyrolyzates in poly(vinyl chloride) has been studied by pyrolysis–gas chromatography–mass spectroscopy. Isotopic distributions of pyrolyzates from experiments with perdeutero-PVC show that pure conjugated aromatic pyrolyzates (e.g., benzene, styrene, naphalene, biphenyl, anthracene) are formed mostly via intramolecular cyclization. Mixed aromatic-alphatic pyrolyzates (e.g., toluene, indene, methylnaphthalene) are formed at least partially via intermolecular (crosslinking and/or hydrogen transfer) mechanisms. Direct scission of the PVC chain to form chlorine-containing pyrolyzates is a very minor degradation pathway. Most chlorine-containing “pyrolyzates” from PVC are due to secondary reactions of HCl with the environment or with non-PVC compounding ingredients. No evidence was found for oxygen-containing pyrolyzates derived from the PVC backbone under conditions of nonflaming pyrolysis in air.

Manufacture of ethylene from synthesis gas (D#75,673-C1)

Abstract: This invention concerns a two-step process for the preparation of ethylene from mixture of carbon monoxide and hydrogen (commonly known as synthesis gas) by reaction of said carbon monoxide/hydrogen mixtures with a carboxylic acid in the presence of one or more ruthenium catalyst complexes to form an ethyl ester of said carboxylic acid coreactant, followed by pyrolysis of said ethyl ester intermediate to ethylene.

Pyrolysis and combustion of cellulose. VII. Thermal analysis of the phosphorylation of cellulose and model carbohydrates during pyrolsis in the presence of aromatic phosphates and phosphoramides

Abstract: Thermal gravimetric analysis, differential scanning calorimetry, and derivative thermal gravimetric analysis were utilized to characterize the thermal interactions between cellulose, 1-6, anhydro β-D-glucopyranoside, and D-glucose and model phosphate and phosphoramide flame retardants. The phosphoramides induced higher char yields than the phosphates during the pyrolysis of the mixtures of carbohydrates and organophosphorus compounds. Exothermic reactions attributed to phosphorylation and char formation were observed with each of the phosphoramide/carbohydrate mixtures and were absent with the phosphates. The individual phosphorus compounds studied showed similar thermal behavior with each of the carbohydrates indicating that the mode of interaction for these mixtures was similar. Isothermal gravimetric analysis of the organophosphorus/carbohydrate mixtures was used to measure the rate of decomposition weight loss from isothermal conditions. This weight loss was used as an indication of rate of fuel formation. The kinetics observed for these measurements indicated that the phosphoramide mixtures underwent a rapid weight loss to a final char with an effective Eact of about 55 kcal/mol while the phosphate mixtures exhibited effective Eact′s for decomposition lower than those observed for the pure carbohydrates. Mixtures of glucose with selcted arylphosphoramide esters were pyrolysed in order to determine the effect of lability of the leaving group on char formation. Gas chromatographic analysis of the pyrolysis products indicated that phenol was the favored leaving group in comparison with aniline units, but char promotion appeared to be dependent on the number of P-N bonds present in the original phosphoramide. Electron spectroscopy for chemical analysis indicated that chemically similar chars were obtained from the different organophosphorus/carbohydrate combinations.

Process for the pyrolysis of waste materials

Abstract: The emission of halogens and sulfur dioxide and the formation of water-soluble compounds of heavy metals are suppressed in the pyrolysis of waste in a carbonization zone at a temperature in the range from 300° to 600° C. by adding a fine-grained basic material to the waste prior to completion of the pyrolysis of the waste in the carbonization zone.

Organic compounds in coal: Structure and origins

Abstract: Traditionally, coal structure has been studied by characterization of pyrolysis liquids and also by examining the solvent extracts from coal. We have combined these 2 techniques to characterize more fully Wyodak subbituminous coal. The organic compounds obtained by pyrolysis in a hydrogen atmosphere and by benzene-ethanol extraction of Wyodak coal were characterized using column chromatography, GC, GC-MS, 1 H-NMR, and 13 C-NMR. We have detected in the extract, ferruginol, a C 20 H 30 O naturally occurring diterpene phenol, which is closely related to abietic acid, as well as large amounts of long-chain fatty acids. Moreover, sclarene, a triene diterpene hydrocarbon related to sclareol was identified. To our knowledge this is the first time that sclarene has been reported in coal. The coal extracts contained only small amounts of normal alkanes (0.4% of coal on DMMF basis), whereas the pyrolysate contained significant amounts (2.4% of coal on DMMF) of these components. We suggest that these saturated hydrocarbons are produced by thermal decarboxylation of the long-chain fatty acids and also from cleavage of the long-chain alkyl moieties attached to the polymeric structures of the coal. The most interesting pyrolytic products are a series of C 14 C 34 long-chain alkylbenzenes. These components were not detected in the extract. Prist-1-ene and prist-2-ene were identified in the coal pyrolysis liquid, indicating that pristane was chemically bound in the coal structure.

Hydrocarbon cracking with mixture of zeolites Y and ZSM-5

Abstract: A hydrocarbon cracking catalyst comprises an ultrastable Y-type crystalline zeolite, a small pore crystalline ZSM-type zeolite, an inorganic oxide matrix and, optionally, a porous inert component. The cracking catalyst has a high activity and selectivity for the production of high octane naphtha fractions from higher boiling point hydrocarbonaceous oils. Catalytic cracking processes utilizing the catalyst are also provided.

Dielectric loss microwave degradation of polymers: Cellulose

Abstract: The pyrolysis of organic waste polymers to produce fuels and chemicals is of interest to augment petroleum-based processes. The wide variety of pyrolysis products of low yield and the uncertain role that heat transfer rate plays in determining these have been deterrents to utilization in the past. A possible approach to increased selectivity for products is to heat them rapidly and homogeneously with the aim of narrowing the product distribution. A very rapid means of homogeneous heat transfer throughout the substrate is microwave heating. A laboratory study has been done to determine what effect high-intensity microwave energy has on the thermal degradative pathways of cellulose. The product distribution found when cellulose is pyrolyzed in the absence of a microwave discharge is similar to that found in conventional furnace pyrolysis. The major products are levoglucosan (27%), carbon dioxide (2–5%), water, and charred residue. However, the total heat-up and reaction times for even large pellets are reduced to less than 2–3 min when high-intensity microwave irradiation is employed. Effects of pressure and microwave power are reported. Low external gas temperature also prevents secondary reactions.

Effect of metal oxides on the evolution of aromatic hydrocarbons in the thermal decomposition of PVC

Abstract: The thermal decomposition of poly(vinyl chloride) (PVC) mixed with several metal oxides was investigated by direct pyrolysis in a mass spectrometer (MS) and flash pyrolysis–gas chromatography. Our results show that the thermal decomposition of PVC occurs in two stages. Unsubstituted aromatic hydrocarbons (benzene, naphthalene, and anthracene) are evolved mainly in the first stage, alkyl-aromatics (e.g., toluene) in the second. Although the addition of some metal oxides results in an overall suppression of aromatic hydrocarbons, the unsubstituted aromatics are much more suppressed with respect to alkyl-aromatics. Furthermore, the formation of ZnCl2 and SnCl4 was revealed by the mass spectra of PVC–metal oxide pyrolysates. This suggests that, at least in these two cases, metal chlorides are responsible for aromatic hydrocarbon suppression. With this information a detailed reaction mechanism could be formulated for the thermal degradation of PVC.

Fluidized coal pyrolysis apparatus

Abstract: Method and apparatus for pyrolyzing agglomerative coals which comprises introducing a fluidized bed of hot char particles into a pyrolysis chamber or reactor, and injecting upwardly into the chamber a high velocity jet of agglomerative coal particles in a carrier gas, the fluidized hot char particles surrounding the high velocity coal jet and heating the coal particles to yield gaseous products and char. The hot char particles in the fluidized state and disposed around the coal jet are entrained in the upwardly expanding coal jet and mixed with the coal particles, so that by the time the coal particles contact the pyrolysis chamber wall, such coal particles being heated by the char have passed through the tacky state and are no longer tacky and do not adhere to the chamber wall. The gaseous product and char formed during pyrolysis are rapidly removed from the pyrolysis chamber, and such char can be separated, e.g. in a cyclone, reheated and introduced into the fluidized bed of char particles as a fresh source of heat. The hot char particles from the fluidized bed which are entrained in the coal jet are removed from the pyrolysis chamber with the gaseous product, without any appreciable recirculation or mixing of such entrained char particles back into the fluidized char within the pyrolysis chamber.