Hydrocarbon Gas Production Research Articles

Flash hydrogenation of coal. 3. A sample of US coals

The susceptibility of a group of US coals to the production of light gaseous and liquid hydrocarbons during flash hydrogenation is examined. Eight coals ranging from lignite to high-volatile A bituminous and representing five provinces, have been flash heated in 101.3 MPa of flowing hydrogen using a bench scale reactor. A 0.6 s gas phase residence time was provided to hydrocrack the vapour products. Temperatures ranged from 750 to 850°C, where maximum yields of ethane and BTX (benzene+toluene + xylene) are found. The carbon conversion decreased with increasing rank at fixed reaction conditions. Methane yields are highest for lignite. Peak ethane yields range from 6.4 to 9% carbon conversion. BTX yields have a shallow maximum at intermediate ranks, decreasing towards high and low rank coals. Total liquid yields range from 14 to 43%. Although a definite variation of yield with rank is evident, the trends, especially total liquid yields, are attended by considerable scatter. Rank is not the only, and indeed may not be the most significant variable in determining the yield of individual species in flash hydrogenation. To establish the significant variables a stepwise regression procedure was applied to the experimental data using information from the elemental, proximate and petrographic compositions of the coals as independent variables. Two variables are adequate in all cases to correlate species yield and coal properties. Exinite appears to be capable of increasing the amount of liquid obtained from other macerals.

Mechanisms leading to process improvements in lignite liquefaction using CO and H 2S

Optimum distillate yields from US lignites can be as high on a dry, ash-free basis as those obtained from bituminous coals, but only if the vacuum bottoms are recycled. Lignites are more readily liquefied if the reducing gas contains some carbon monoxide and water, which together with bottoms recycle has proven to yield the highest conversions and the best bench-unit operability. The recycle solvent in the reported tests consisted of unseparated product slurry, including coal mineral constituents. Variability in coal minerals among nine widely representative US low-rank coals did not appear to correlate with liquefaction behaviour. Addition of iron pyrite did, however, improve yields and product quality, as measured by hydrogen-to-carbon ratio. Future improvements in liquefaction processes for lignite must maintain high liquid yields at reduced levels of temperature, pressure, and reaction time whilst using less reductant, preferably in the form of synthesis gas ( CO + H 2) and water instead of the more expensive pure hydrogen. Understanding the process chemistry of carbon monoxide and sulphur (including H 2S) during lignite liquefaction is a key factor in accomplishing these improvements. This Paper reviews proposed mechanisms for such reactions from the viewpoint of their relative importance in affecting process improvements. The alkali formate mechanism first proposed to explain the reduction by CO does not adequately explain its role in lignite liquefaction. Other possible mechanisms include an isoformate intermediate, a formic acid intermediate, a carbon monoxide radical anion, direct reaction with lignite, and the activation of CO by alkali and alkaline earth cations and by hydrogen sulphide. Hydrogen sulphide reacts with model compounds which represent key bond types in low-rank coal in the following ways: (1) hydrocracking; (2) hydrogen donor; (3) insertion reactions in aromatic rings; (4) hydrogen abstraction, with elemental sulphur as a reaction intermediate; and (5) catalysis of the water-gas shift reaction. It appears that all of these reaction pathways may be operative when catalytic amounts of H 2S are added during liquefaction of lignite. In bench recycle tests, the addition of H 2S as a homogeneous catalyst reduced reductant consumption as much as three-fold whilst maintaining high yield levels when the reaction temperature was reduced by 60°C. Attainment of the high distillate yield at 400°C was accompanied by a marked decrease in the production of hydrocarbon gases, which normally is a major cause of unproductive hydrogen consumption and solvent degradation via hydrocracking. Processing with synthesis gas and inherent coal moisture using bottoms recycle and H 2S as a catalyst appears to be the most promising alternative combination of conditions for producing liquids from lignite at reduced cost.

Paraquat‐induced production of hydrocarbon gases

AbstractParaquat dichloride (1,1′‐dimethyI‐4,4′‐bipyridylium dichloride) induced the production of the hydrocarbon gases propane, ethane and ethylene in the xanthophycean microalga Bumilleriopsis filiformis. Formation of these gases was dependent on the light intensity and photosynthetic electron transport. Diquat dibromide (1,1′‐ ethylene‐2,2′‐bipyridylium dibromide), having a higher midpoint potential than paraquat dichloride, induced an even higher evolution of the gases. A total lack of oxygen inhibited the production of gas, while a low oxygen concentration (4–6% by volume) stimulated paraquat‐induced gas formation. Culturing algae autotrophically, in a medium with a higher iron content, also increased the production of gases in the presence of the herbicide. Formation of these gases is an indication of the peroxidation of membrane lipids which, according to previous results, is correlated with a decrease of photosynthetic electron‐transport activity.

Reaction Kinetics of Laboratory-Simulated Kerogen Maturation: ABSTRACT

Application of time and temperature evaluations to maturation and hydrocarbon formation requires knowledge of the chemical kinetics of the maturation process. Lopatin and others have used first-order kinetics, assuming linear dependence of maturation on time for a given temperature and have derived a rate constant whose temperature dependence is governed by the Arrhenius equation. This model may be inadequate as maturation data used in such first-order kinetic equations have generally yielded Arrhenius factor activation energies which vary widely with temperature. We report here a detailed kinetic analysis of the laboratory-simulated maturation of several distinct kerogens having different source organic compositions and utilizing data for the production of CO2, CH4, and higher hydrocarbon gases as a function of time and temperature. In all cases, the dependence of maturation on time departs from linearity. Empirically a dependence on t12/ gives the best fit to the data, indicating possible product inhibition of the maturation process. We develop a simple chain reaction model incorporating this feature for both short and long reaction times. The model yields an effective rate constant which should obey the Arrhenius equation and consistently gives temperature-independent composite activation energies of the same approximate magnitude as is implied by Lopatin's model. The nature of the mineral substrate present with the kerogen influences the rate of maturation, both directly by catalytic action in some cases and indirectly by adsorption of product. Our results suggest a marked difference in kerogen maturation kinetics between closed and open systems, which must be considered in interpreting and comparing laboratory simulations and which may be of considerable significance for hydrocarbon genesis in the field. This may be reflected in a dependence of the kinetics on lithology and porosity of the source or rock unit. End_of_Article - Last_Page 1685------------

Rapid pyrolysis and hydropyrolysis of Canadian coals

A range of Canadian coals were subjected to variable heating-rate conditions in a variety of atmospheres. Heating rate was found to have little effect on total weight loss of the coal, but a dramatic effect on the actual composition of products. High heating rates substantially increased the yield of light hydrocarbons. Operation in ≈100 KPa (1 atm) H 2 at high heating rate resulted in 5% conversion to light hydrocarbon gas and liquid products. Operation in ≈10 MPa (100 atm) H 2 at a heating rate of 600 Ks −1 gave 10% coal conversion to light liquid products (benzene, xylene, toluene).

Age-related changes in lipid peroxidation as measured by ethane, ethylene, butane and pentane in respired gases of rats

This research measured lipid peroxidation products in rats of varying age by a new method. Wistar male rats, 4, 12, 22 and 32 months old, were examined for lipid peroxidation in vivo by measurement of ethane, ethylene, butane and pentane in breath gases of intact animals. In the older rats, the amounts of the four hydrocarbons exhaled were greater than those in younger rats. All hydrocarbons tested were related to age by an exponential relationship, and quantitatively, ethane and ethylene were related to age with a linear regression fit correlation coefficient, 0.466–0.622 (p<0.01-0.001). When hydrocarbon gas production of 32 month-old rats was compared with that of 4 month-old rats, the greatest ratio was that for pentane (1.99). The following order was ethylene >ethane>butane. There were significant differences in the production of all hydrocarbons between 32 month-old rats and 4 month-old rats. Thiobarbituric acid reactants in serum exhibited an increasing tendency with age, but the values of 32 month-old rats were lower than those of 22 month-old rats. However, the differences between the age groups were not significant. These results showed that the measurement of hydrocarbons in the rats'breath was a sensitive index of in vivo peroxidation during aging.

The flash hydropyrolysis of lignite and sub-bituminous coals to both liquid and gaseous hydrocarbon products

Lignite and sub-bituminous coals, ground to minus 100 mesh, have been hydrogenated with preheated hydrogen in a highly instrumented 1-in. I.D. × 8-ft, entrained downflow tubular reactor system designed to be operated at up to 900°C and 4000 p.s.i. The heat-up rate of the coal particles have been calculated to be in the order of 30,000 to 50,000°C/sec. Product yields of 10% BTX were observed when using lignite and 13% when using sub-bituminous coal, based on conversion of carbon contained in the coal, and when operating at 2000 to 2500 p.s.i. and 750° to 775°C. Methane yields in excess of 80% have been observed at 2500 p.s.i. and 875° to 900°C. Coal particle residence times are in the order of 4 to 12 sec and the effect of residence time is studied by the use of product sample taps located along the length of the reactor. Hydrogen to coal feed ratios as low as approximately 0.2 (lb/lb) were studied and methane concentrations as high as 34% in the process stream were obtained. Nitrogen and sulfur balances were made on the coal, char products and both the liquid and gaseous effluents. A reaction scheme and kinetics model have been developed to which the experimental data is applied to calculate rate constants and activation energies. Relative economic evaluations are made using the most recent experimental results assuming an integrated system using flash hydropyrolysis to produce: (a) motor fuel; (b) pipeline gas; and (c) motor fuel and pipeline gas.

Microsomal metabolism of hydroxyl radical scavenging agents: Relationship to the microsomal oxidation of alcohols

Previous studies provided indirect evidence that hydroxyl radicals are involved in the oxidation of primary aliphatic alcohols by rat liver microsomes. In the current study, three ·OH scavengers were used as chemical probes to evaluate ·OH production by microsomes. The scavengers and their products were 3-thiomethylpropanal (methional) and 2-keto-4-thiomethylbutyric acid, which yield ethylene gas, and dimethylsulfoxide, which yields methane gas. We observed that microsomes actively generate the appropriate hydrocarbon gas from each scavenger when electron transport is initiated with NADPH. Hydrocarbon gas production is augmented by 0.5 m m azide, an agent which inhibits catalase and, thereby, permits H 2O 2 to accumulate. However, no metabolism of scavengers occurs when H 2O 2 is added in the absence of microsomes. These results are consistent with a presumed role for H 2O 2 as a precursor of hydroxyl radicals. In addition, no metabolism of scavengers occurs when azide and H 2O 2 are added either to boiled microsomes or to intact microsomes in the absence of electron transport (NADPH-generating system omitted). Therefore, both H 2O 2 and simultaneous electron transport are required. Ethanol inhibits the metabolism of the scavengers. Similarly, the scavengers inhibit the oxidation of ethanol to acetaldehyde; inhibition in the presence of azide is competitive. These latter results indicate a competition between the scavengers and ethanol for metabolically generated ·OH in microsomes. The specificity of this interaction is evident from the observation that the scavengers do not affect the activities of microsomal aminopyrine demethylase or aniline hydroxylase. Two model ·OH-generating systems (Fenton's reagent and iron-EDTA-ascorbate) were also studied and they produced acetaldehyde from ethanol and hydrocarbon gases from the scavengers. These results, as a whole, tend to verify a role for ·OH in the microsomal oxidation of alcohols.

Chemical Evidence for Production of Hydroxyl Radicals During Microsomal Electron Transfer

Rat liver microsomes generate methane from dimethyl sulfoxide and ethylene from either methional or 2-keto-4-thiomethylbutyric acid during electron transfer initiated by reduced nicotinamide-adenine dinucleotide phosphate (NADPH). Hydrocarbon gas production is suppressed by hydroxyl radical scavenging agents. Azide, an inhibitor of catalase, augments the production of hydrocarbon gases. These observations constitute chemical evidence for the generation of hydroxyl radicals by microsomes.

Hydrocarbon gases produced during in vitro peroxidation of polyunsaturated fatty acids and decomposition of preformed hydroperoxides.

Hydrocarbon gases have been used previously as an index of lipid peroxidation in vivo and in vitro. In vitro experiments are reported on the formation of hydrocarbon gases from peroxidizing omega-3 and omega-6 fatty acids. Hydrocarbon gases were not released during a 20-hr peroxidation phase but were released following the decomposition of hydroperoxides by addition of excess ascorbic acid. The major hydrocarbon gas products in iron, copper, or hematin catalyzed peroxidation systems were ethane or ethylene from linolenic acid, and pentane from linoleic acid and arachidonic acid. Calculations of the ratios of hydrocarbon gases formed were based on fatty acid decrease and/or change in diene conjugation and peroxide values. Depending on the fatty acid, catalyst, and calculation basis used, pentane formation was as high as 1.3 mol %, ethane 4.3 mol %, and ethylene 10.6 mol %.

Gases Produced during γ Irradiation of the Monobutylbenzenes

The four isomeric monobutylbenzenes have been γ-irradiated and the gases produced have been analyzed by gas chromatography. The most abundant gaseous product is hydrogen. The relative yields of hydrogen indicate a relationship to the number of benzylic hydrogens in the starting butylbenzene. The most abundant gaseous hydrocarbon products are ${\rm C}_{3}\text{'}{\rm s}$ for n-butylbenzene, C1 and ${\rm C}_{2}\text{'}{\rm s}$ for sec-butylbenzene, ${\rm C}_{3}\text{'}{\rm s}$ and C1 for iso-butylbenzene, and C1 for tert-butylbenzene. The gaseous products indicate that reactions forming benzylic intermediates predominate.

Der Einfluß von Temperatur und Feuchtigkeit auf die Bildung von Äthylen in Fichtenstreu

The production of light hydrocarbon gases by litter of Picea abies was measured by means of gas chromatography. Ethylene was the only gas which occurred in significant concentrations; more than 70% was found in the litter atmosphere. The rate of ethylene production was increased by raising the temperature from 18 to 37°C. Ethylene formation was also correlated with the water content of litter, and was affected by rewetting the air-dried material.

THE OCCURRENCE OF ETHYLENE IN ANAEROBIC SOIL

SummaryThe production of ethylene and other hydrocarbon gases by soils under anaerobic conditions was measured by gas chromatography. Ethylene was the only hydrocarbon gas which occurred in physiologically significant concentrations; more than 20 ppm was found in several soils after 10 days at 20°C. These concentrations were considerably higher than those which were known to cause severe reductions in the extension of root axes of some plant species.Experiments with sterilized and unsterilized soil indicated that ethylene was produced by enzyme activity and not by chemical action. The gas was found in soil when the oxygen concentration fell below 2 per cent; total evolution was correlated with organic matter content, and was affected by drying and rewetting and by the growth of plant roots. The rate of production was increased by raising the temperature and by addition of glucose or peptone; high concentrations of nitrate depressed the rate, but sulphate and phosphate had little effect.It is concluded that ethylene may be a significant factor in causing injury to crop plants under waterlogged conditions and also in situations where anaerobic pockets occur within a mainly aerobic soil structure, provided that escape of the gas from the soil is impeded sufficiently to allow inhibitory concentrations to build up in the vicinity of plant roots.

Production of Carbon Monoxide and Gaseous Hydrocarbons in Seawater: Relation to Dissolved Organic Carbon

Carbon monoxide, ethylene, and propylene were produced in illuminated, cell-free distilled water or natural seawater systems to which dissolved organic matter produced by phytoplankton had been added. Methane and the higher saturated gaseous hydrocarbons were not produced. In the dark, little or no carbon monoxide and no hydrocarbons were produced in the distilled water systems; only carbon monoxide was produced in natural seawater, but less was produced than in the light.

Photochemistry of Allyl Chloride in Liquid and Solid State

AbstractThe photolysis at 2537 Å of liquid allyl chloride at 27°C and of solid allyl chloride at 77°K has been studied. The gaseous hydrocarbon products from the liquid photolysis were allene and propene in nearly equivalent amounts. The products from the solid photolysis were allene, propene, and cyclopropane; the yield of C3H6 hydrocarbons averaged 1.7 that of allene, while the average yield of propene alone was 1.3 that of allene. By the use of aqueous acetone as an actinometer, the quantum yield of C3 hydrocarbons in the liquid was found to be about 0.01. The primary process proposed is a breaking of the carbon‐chlorine bond to give allyl radical. A parallel primary process may be the formation of cyclopropyl radical. For the liquid the only secondary process needed to account for the products is the disproportionation of allyl radicals to give allene and propene. For the solid, in addition to disproportionation, abstraction of hydrogen atoms from allyl chloride is postulated.

Synthesis of cis and trans polymers of dienes on oxide catalysts and investigation of their structure and properties

AbstractCrystalline 1,4‐trans polymers of butadiene and isoprene of regular structure are formed in polymerization of dienes in a chromia catalyst (chromium oxide on aluminum silicate). 1,4‐trans‐Polybutadiene with a specific gravity of 1.015 has crystalline modifications melting at 75 and 135°C. The 1,4‐trans‐polyisoprene resembles natural gutta‐percha. When α‐butylene undergoes polymerization on the same catalyst, a crystalline polymer is formed of specific weight 0,96 and melting point ca. 140°C. Any disturbance of the 1,4‐trans‐structure by copolymerization of butadiene or isoprene with other compounds leads to a loss of capacity for crystallization and to transition to the high elastic state. The butadiene‐isoprene copolymer contains about 55% butadiene links while preserving the 1,4‐trans structure of the chain and has a glass temperature of ca. −90°C., coinciding with the value calculated on the basis of a linear relation between the copolymer composition and the glass temperature. By copolymerization ethylene units could be incorporated in the trans‐polyisoprene chain to the extent of ca. 40 mole‐%. The polymer formed has a glass temperature of −76°C., as compared with −71°C., for 1,4‐polyisoprene. Polymerization of butadiene induced by the cobalt oxide‐diethyl‐aluminum halides proceeds at a high rate, even at 0°C. The polybutadiene formed contains predominantly links cis‐1,4 (about 85%) and only a small quantity (5–8%) of 1,2 links. Owing to the high content of 1,4 links the polymer has a glass temperature as low as −115°C. Unlike organometallic‐titanium tetrachloride systems, interaction between cobalt oxides and organoaluminum compounds in the temperature range 0–80°C. is not accompanied by formation of gaseous hydrocarbon products.

HYDROGENATIONS IN A TETRALIN MEDIUM: IV. DESTRUCTIVE HYDROGENATION OF GRAIN SCREENINGS

The destructive hydrogenation of grain screenings in a tetralin medium has been investigated. With an excess of tetralin, at least 3 to 1 by weight, more than 50% of the screenings can be reduced to oils and about 15% to solid residue. Catalysts are effective by virtue of the fact that they greatly increase the rate of reaction, and also increase the production of hydrocarbon gases at the expense of carbon dioxide.