Abstract: A process and system for separating water from bio-oil by using a partial condenser. The process comprises partially condensing vapor conversion products from a biomass conversion reaction to produce a water-rich overhead stream and a water-depleted stream comprising condensed bio-oil. The partial condenser removes a substantial portion of the water from the bio-oil, while providing an effective and flexible process for producing bio-oil.

Abstract: Waste processing system, for performing a waste processing process, the system including a shredder, a grinder and a steam explosion device such as a cooking extruder. The waste processing system is used to process raw waste, such as consumer waste, into an end product such as pellets. The waste processing includes an acid treatment step to sanitize, purify and/or increase a cellulose content of the waste. The acid is preferably a weak acid and/or an organic acid.

Abstract: Recycling a metal/organic laminate continuously involves providing a reactor having a first chamber with a first rotary stirrer, a second chamber with a second rotary stirrer, each chamber containing particulate microwave absorbing material, introducing laminate and additional absorbing material into the first chamber under a reducing or inert atmosphere, stirring and applying microwave energy sufficiently to pyrolyze organic material, transferring a portion of the mixture to the second chamber where it is stirred and microwave energy applied to pyrolyze remaining organic material, delaminate or delaminated metal migrating toward and floating on the upper surface of the mixture, where the second stirrer rotates in a horizontal plane and fluidizes the mixture to give the upper surface of the mixture a radial profile biasing metal floating to migrate radially outwardly, and recovering metal from an exit.

Abstract: A method for collecting biomass, such as straw, and for producing a pyrolysis liquid, such as oil or tar, from the biomass, includes the step of collecting the biomass from a growth site, e.g. a field, by means of a mobile unit. The biomass is continuously fed into a pyrolysis apparatus accommodated by the mobile unit, as the mobile unit is moved across the growth site. While the biomass is processed in the pyrolysis apparatus, further biomass is simultaneously being collected. The pyrolysis apparatus may be a flash pyrolysis or fast pyrolysis apparatus relying on centrifugal forces for forcing biomass towards a reactive surface in a pyrolysis reactor. The mobile unit may be self-propelled.

Abstract: A fast pyrolysis apparatus (200) for producing pyrolysis liquid, such as oil or tar, char and pyrolysis gas from biomass, such as straw, comprises a centrifuge chamber (204) and a rotor (210) arranged to impart rotation on the biomass in the centrifuge chamber to force the biomass outwardly under the action of centrifugal forces. A furnace (206) arranged coaxially around the centrifuge chamber (204) maintains the temperature at an outer reactive wall of the centrifuge chamber at an elevated temperature to effect the pyrolysis process at or near the reactive wall. The apparatus comprises a condenser (218) arranged coaxially with and surrounded by the centrifuge chamber (204). The apparatus may be accommodated by a mobile unit for simultaneously collecting biomass from a field and processing the biomass in the apparatus.

Abstract: A rapid thermal conversion process for efficiently converting wood, other biomass materials, and other carbonaceous feedstock (including hydrocarbons) into high yields of valuable liquid product, e.g., bio-oil, on a large scale production. Biomass material, e.g., wood, is feed to a conversion system where the biomass material is mixed with an upward stream of hot heat carriers, e.g., sand, that thermally convert the biomass into a hot vapor stream. The hot vapor stream is rapidly quenched with quench media in one or more condensing chambers located downstream of the conversion system. The rapid quenching condenses the vapor stream into liquid product, which is collected from the condensing chambers as a valuable liquid product. The liquid product may itself be used as the quench media.

Abstract: Useful byproducts are recovered through the pyrolytic processing of biomass material such as vegetation, paper, or worn tires. The process is conducted in a sealed enclosure under vacuum or other controlled atmosphere. The biomass material is ablated and burned by crunching between counter-rotating rollers whose inner walls have been exposed to a highly heated fluid. The biomass material is preheated by injecting into the feeding duct super-heated dry steam. A condenser within the enclosure reduces resulting vapors into oils that can be drained from the enclosure pan. Solid combustion residue is abstracted from the enclosure by an Archimedes screw.

Abstract: A catalytically activated vacuum distillation system, several novel component parts of said system, a process for producing carbon based products and novel carbon black that is produced from such a system and process.

Abstract: Described is a thermal decomposition treatment system and method of using the thermal decomposition treatment system wherein flammable waste is inputted into a trash burner which is shielded from air or gas and the waste is thermally decomposed and carbonized. The thermal decomposition treatment chamber includes a plurality of heating tubes wherein the flammable waste is inputted into the chambers while hot air is passed through the heating tubes which indirectly heats the flammable waste in an anaerobic environment the resulting gases are purified, recovered and reused.

Abstract: A method for treating saturated activated coke comprises the following steps: A) The saturated activated coke is subjected to a dehydration treatment so that the water content in the activated coke is ?25%; B) The product obtained from step A is dried at a starting temperature of 120° C.-150° C.; C) The product obtained from step B is subjected to dry distillation and the condition of the dry distillation is that: by heating to a final temperature for the drying of 500° C.-600° C. at a speed of 4° C.-10° C./min and maintaining for 10-60 minutes, the organics adsorbed on the surface and in the pores of the activated coke is cracked, volatilized and carbonized; D) The product obtained from step C is activated and the activation condition is that: after heating to 800° C.-950° C. at 2° C.-8° C./min, a stream is supplied, wherein the weight ratio of the activated coke to the stream is 1:0.5-5 and the activation time is 0.5-2 h. The activated coke after several times of treatment can be used as the fuel.

Abstract: A delayed coking process for making substantially free-flowing coke, preferably shot coke. A coker feedstock, such as a vacuum residuum, is heated in a heating zone to coking temperatures then conducted to a coking zone wherein volatiles are collected overhead and coke is formed. At least one polymeric additive is added to the feedstock prior to it being heated in the heating zone, prior to its being conducted to the coking zone, or both.

Abstract: Apparatus for the pyrolysis of solid waste material includes a thermal reactor including an elongate hollow housing with a reaction chamber disposed within the housing. The thermal reactor is vertically oriented in order to cause solid waste material fed thereinto to pass through said reaction chamber by the force of gravity and a plurality of vanes are disposed for both conducting heat into said reactor chamber and for tumbling said solid waste material as said solid waste material passes through said reaction chamber. Inlets and outlets are provided for passing oxygen transversely through the reaction chamber.

Abstract: The method enables the attainment of an open and continuous flow of an aqueous slurry containing carbonaceous solids into a high-pressure and high temperature environment which will result in the occurrence of at least two chemical processes: (1) aqueous pyrolysis (hydrous pyrolysis) and (2) hydrolytic disproportionation. This combination of processes will effect conversion of suspended organic materials into hydrocarbon liquids or gases depending on the mix of the temperature, pressure, and residence time in the reactor. Thereafter, the hydrocarbon-bearing slurry can be refined (separated into various constituents) using standard existing technologies.

Abstract: The present invent provides improved rapid thermal conversion processes for efficiently converting wood, other biomass materials, and other carbonaceous feedstock (including hydrocarbons) into high yields of valuable liquid product, e.g., bio-oil, on a large scale production. In an embodiment, biomass material, e.g., wood, is feed to a conversion system where the biomass material is mixed with an upward stream of hot heat carriers, e.g., sand, that thermally convert the biomass into a hot vapor stream. The hot vapor stream is rapidly quenched with quench media in one or more condensing chambers located downstream of the conversion system. The rapid quenching condenses the vapor stream into liquid product, which is collected from the condensing chambers as a valuable liquid product. In one embodiment, the liquid product itself is used as the quench media.

Abstract: The present invention relates to a system and a process for obtaining phenanthrene of about 95% purity from coal tar distilled fraction containing crude phenanthrene by performing fractional distillation at a reduced pressure of 50 mm mercury and at a temperature range of 160-180° C. to obtain first distilled fraction containing acenaphthene and fluorene; a second distillate fraction at a temperature range of 200-230° C. containing phenanthrene, anthracene and traces of carbazole; followed by re-distilling the second distillate fraction at a temperature range of 210-224° C. to finally obtain pure phenanthrene and a residue which is again used for the recovery of residual phenanthrene by re-distillation at a temperature range of 210-224° C.

Abstract: A method for the pyrolosis of biomass with the aid of a heating element and a feed for guiding the biomass. During pyrolysis, the heating element and the biomass are pressed against each other at a pressure of 5 bars-80 bars. A device for pyrolysing biomasses, comprises a material supply and a pyrolysing station. The material supply comprises elements for generating a pressure of between 5 bars and 200 bars, pressing the raw material which is to be pyrolysed against the pyrolysing station. The pyrolysing station comprises a heating element which is heated to a temperature of between 300° C. and 1000° C. in an operational state.

Abstract: Organic matter, i.e., biomass, fibrous plant matter, organic chemicals or organic waste, or other carbon-based matter is converted to synthesis fuel gas by reactive contact with superheated steam at a temperature of about 200 to 2000 degrees C., typically 500 to 1700 degrees. A reactor has a generally tubular envelope, a rotor within the envelope, and hot reaction spaces disposed annularly within the wall of the tubular envelope. The steam and biomass particles can be heated to the required temperatures by RF induction. The product gases include H2, CO, and CO2 in ratios controlled by a programmable controller. Control of temperature, biomass feed rate and water flow preselects the output synthesis gas mix. The synthesis gas may be processed into portable liquid fuels, or can be used directly in a fuel cell.

Abstract: An object of the present invention is to provide a method of efficiently decomposing waste plastics, organics, and particularly medical waste composed of varieties of plastics. The present inventors established a method of efficiently decomposing waste plastics, organics, and particularly medical waste mainly composed of varieties of plastics by optimizing conditions in a decomposition process and introducing a process of adsorbing and removing generated harmful gases, and have completed the present invention.

Abstract: Method and apparatus used in the field of waste management for utilizing recoverable waste products as efficiently as possible. The invention reduces the environmental impact of such a method to a minimum. The recoverable waste products and non-recoverable waste products are fed into one end of a substantially horizontally fixed container as material, and are transported in a continuous or discontinuous manner to another end of the container, 60–80% of energy input being carried out on the material in an area of a first quarter of the container, and a remaining 20–40% of energy input being transferred to the material in other areas of the container.

Abstract: A plastic as a material to be treated and an additive such as unsaturated fatty acid oil are mixed, and the mixture is heated in a pyrolysis tank at a temperature of 300° C. to 450° C. by a heating member to thereby thermally decompose the mixture. A gas component produced during the heating process is then removed and a pyrolysate is thus produced.

Abstract: Wastes mainly containing any one or two or more of raw garbage, waste lumber, paper diapers, waste plastics, and organic sludge discharged from the food industry, common houses, etc. are exposed to high-temperature steam of 510 to 900° C. in an oxygen-free state, preferably while being stirred, to be carbonized. Thereby, the amount of wastes is reduced safely and efficiently with no fear of generating harmful substances such as dioxin, and moreover the carbonized wastes can be reused effectively for applications to fuel or the like.

Abstract: In a method of producing coke for metallurgy by carbonizing a coal blend obtained by blending plural raw coals in an coke oven, a coal blend containing not less than 60 wt % of a medium coking coal of middle coalification degree and low fluidity having an inert component content of not less than 30% is used as a coal charged into the coke oven, whereby a great amount of raw coal of a brand being cheap and easily available can be blended in a great amount and hence coke for metallurgy having an excellent quality such as strength or the like can be produced by blending few brands of coals as compared with a coal blend of many brands.

Abstract: A pyrolysis process and reactor converts various hydrocarbons such as waste materials, for example, scrap polymers, tires, etc., into various chemical components or amounts thereof, not otherwise produced by conventional pyrolytic processes. A large reactor size is utilized in association with a low heat input per unit weight of charge. A thick pyrolyzate/“char” layer is formed during pyrolysis. The product or various components thereof can be utilized as a fuel or octane additive.

Abstract: A low-energy input process for the pyrolytic conversion of biomass to charcoal or carbonized charcoal is provided. The biomass is sealed in a container, pressurized with air and heated to ignition. Control of pressure by input of air and release of gases to maintain successively lower pressure levels results in a typical time for the conversion of less than 30 minutes.

Abstract: A pyrolysis plant for refuse and a method for screening solid residues provide a sure and trouble-free sieving of a solid material using a sieving device having a configuration which is as simple as possible. A spiral formed by a rod which is wound in a helicoidal manner, or a plurality of such rods, are provided as the sieving device. The rod or rods can rotate around a longitudinal axis. The solid material is introduced into an interior formed by the rod for sieving, preferably with the assistance of an aligning device for longitudinally extended solid material parts. The spirals include, in particular, a bend so that the lodged solid materials can automatically detach themselves. The sieving device is especially suited for sieving pyrolysis residual material.

Abstract: The invention provides a process for the production of charcoal, fuel gas, and potassium from a biomass gassifier.

Abstract: Closed apparatus and processes by which carbon feedstock, is composed of a mixture of non-coking coal fines and another carbonaceous material, such as waste coke fines are disclosed. The coal and coke fines are mixed together and may be formed into solid pieces. The mixture alone or as solid pieces is fired through pyrolyzation into solid pieces of coke, with solid and gaseous by-products of pyrolyzation being recycled for use within the coke-producing closed system, thereby reducing or eliminating release of undesirable substances to the environment. A char-forming binder may or may not be added to the carbon mixture prior to pyrolyzation.

Abstract: The present invention relates to a system and a process for obtaining phenanthrene of about 95% purity from coal tar distilled fraction containing crude phenanthrene by performing fractional distillation at a reduced pressure of 50 mm mercury and at a temperature range of 160-180° C. to obtain first distilled fraction containing acenaphthene and fluorene; a second distillate fraction at a temperature range of 200-230° C. containing phenanthrene, anthracene and traces of carbazole; followed by re-distilling the second distillate fraction at a temperature range of 210-224° C. to finally obtain pure phenanthrene and a residue which is again used for the recovery of residual phenanthrene by re-distillation at a temperature range of 210-224° C.

Abstract: A portable reactor container that contains a removable fire grate enclosure and an incline on its floor that slopes to a discharge port. Heating elements are arranged between the enclosure and the container. A heat recovery section, which may be a water reservoir, surrounds the outside of the container to convert water into steam by absorbing heat leaving the container. The enclosure may be inserted into or removed from the container with a forklift. Wood waste or other wood waste material may be filled into the fire crate enclosure to be transformed into wood charcoal by heating appropriately while the container is hermetically sealed.

Abstract: Closed apparatus and processes by which carbon feedstock, is composed of a mixture of non-coking coal fines and another carbonaceous material, such as waste coke fines are disclosed. The coal and coke fines are mixed together and may be formed into solid pieces. The mixture alone or as solid pieces is fired through pyrolyzation into solid pieces of coke, with solid and gaseous by-products of pyrolyzation being recycled for use within the coke-producing closed system, thereby reducing or eliminating release of undesirable substances to the environment. A char-forming binder may or may not be added to the carbon mixture prior to pyrolyzation.

Abstract: Asphaltene and oil shale are pyrolyzed at substantially atmospheric pressure for producing combustible products and carbonaceous material. A combustor combusts the carbonaceous material and produces flue gases which are supplied to a utilization device, and hot ash which is fed back to the pyrolyzer.

Abstract: Combustible gases from pulverized solid fuel are generated by semi-coking the pulverized solid fuel in a reactor in the absence of oxygen to produce a solids stream that includes carbonaceous material and a gas stream that includes hydrocarbon gases and tar fumes. The carbonaceous material in the solids stream is gasified in a fluidized bed using steam and hot air to produce an output stream that includes combustible gases and coke particles. The output stream is combined with the gas stream to form a combined stream which is separated into a combustible gas stream and a hot particulate stream. At least a part of the hot particulate stream is applied to the reactor.

Abstract: Apparatus (1) for producing gaseous energy which may be used as fuel for driving electricity generating means comprises an oven (2), a ram (11) for feeding gas-producing waste material to the oven (2), gas burners (5) for heating the waste material while in the oven (2), and a collection vessel (25) for collecting gaseous fuel liberated by heating the waste material. The oven (2) and waste material feeder duct (7) connected thereto are of airtight construction, so that combustion of the waste material is not allowed to take place. The airtight oven (2) has a central gasifier section (15) having an inlet end (15a) and an outlet end (15b). The feeder duct (7) is connected to the inlet end (15a) and an outlet duct (16) is connected to the outlet end (15b). The outlet duct (16) extends into the collection vessel (25), which has an upper end housing a gas filter (26) and a lower end connected to an ash receptacle (27).

Abstract: A blast furnace coal is produced by rapidly heating a coal blend having 10 to 30% by weight of a non-slightly-caking coal having softening initiation temperature T with the balance including a caking coal having softening initiation temperature T.sub.0 (T.sub.0 .ltoreq.T +40.degree. C.) at a rate of 1.times.10.sup.3 to 1.times.10.sup.6 .degree. C./min to a temperature region from (T -60.degree. C.) to (T +10.degree. C.) wherein T represents the softening initiation temperature of the non-slightly-caking coal; or rapidly heating a non-slightly-caking coal having softening initiation temperature T and a caking coal having softening initiation temperature T.sub.1 separately at a rate of 1.times.10.sup.3 to 1.times.10.sup.6 .degree. C./min to a temperature region from (T -100.degree. C.) to (T +10.degree. C.), wherein T represents the softening initiation temperature of the non-slightly-caking coal, or a temperature region from (T.sub.1 -100.degree. C.) to (T.sub.1 +10.degree. C.), wherein T.sub.

Abstract: This invention generally relates to a new method and apparatus for the fast pyrolysis of carbonaceous materials involving rapid mixing, high heat transfer rates, precisely controlled short uniform residence times and rapid primary product quench in an upflow, entrained-bed, transport reactor with heat carrier solids recirculation. A carbonaceous feedstock, a non-oxidative transport gas and inorganic particulate heat supplying material are rapidly mixed in a reactor base section, then transported upward through an entrained-bed tubular reactor. A cyclonic hot solids recirculation system separates the solids from the non-condensible gases and primary product vapors and returns them to the mixer. Product vapors are rapidly quenched to provide maximum yields of liquids, petrochemicals, high value gases and selected valuable chemicals.

Abstract: This invention generally relates to a new method and apparatus for the fast pyrolysis of carbonaceous materials involving rapid mixing, high heat transfer rates, precisely controlled short uniform residence times and rapid primary product quench in an upflow, entrained-bed, transport reactor with heat carrier solids recirculation. A carbonaceous feedstock, a non-oxidative transport gas and inorganic particulate heat supplying material are rapidly mixed in a reactor base section, then transported upward through an entrained-bed tubular reactor. A cyclonic hot solids recirculation system separates the solids from the non-condensible gases and primary product vapors and returns them to the mixer. Product vapors are rapidly quenched to provide maximum yields of liquids, petrochemicals, high value gases and selected valuable chemicals.

Abstract: The invention concerns a process for recovering synthetic raw materials and fluid fuel components from used or waste plastics in accordance with patent application P 43 11 034,7. At least a partial flow of the depolymer produced according to this process is subjected, together with coal, to a coking process, fed to a thermal utilization system or introduced as a reducing agent into a blast furnace process. The depolymer can be used as an additive for bitumen and bituminous products.

Abstract: The invention relates to a process for recycling waste which consists essentially of one or more plastics comprising polyvinyl chloride (PVC), in which:the waste is mixed with a heavy oil, in a reactor under an inert atmosphere, at an internal temperature of at least 300.degree. C., and the hydrogen chloride (HCl) which is evolved is collected;the contents of the reactor are then cracked at a temperature of at least 400.degree. C., and at least part of the gases which are evolved are extracted from the reactor;the contents of the reactor are then cooled and the residual solid product is collected.HCl, coke, hydrocarbon gases and various oils are thus mainly obtained.

Abstract: A method for producing a solid fuel from combustible waste includes sorting and grinding the waste, treating the waste by heating in the absence of oxygen in a first pyrolysis reactor and then collecting the waste so treated. Polluting elements in the gases emerging from the pyrolysis are removed while the gases are hot before being directly reused to heat a first pyrolysis reactor so that solids leaving the pyrolysis operation provide a fuel without the pollutants initially contained in the waste. The device for carrying out this method includes a pyrolysis reactor and a unit for supplying an absorbent to a zone wherein the gases generated by pyrolysis are contacted by the absorbent to remove the polluting elements; the absorbent and the decontaminated solids are separated from each other.

Abstract: Heating of polyvinyl chloride, in particular plasticizer-containing polyvinyl chloride, to a temperature of from 250.degree. to 500.degree. C. in the absence of oxygen gives a low-chlorine, carbon-containing residue, plasticizer and hydrogen chloride.

Abstract: A process and apparatus for recovering energy values of waste tar sludge comprises dewatering the waste tar sludge, transporting the dewatered tar sludge in enclosed containers vented through activated carbon to remove volatile hydrocarbons before vapors are vented to the atmosphere, and injecting the dewatered tar sludge into the side wall of a coke oven charging hole along with a stream of coking coal introduced through the top of the charging hole.

Abstract: Metals are recovered from automobile shredder residue by subjecting the shredder residue to vacuum pyrolysis to produce non-condensable gases, condensable hydrocarbon vapors and water vapor, and a solid residue containing non-oxidized metals and a carbonaceous material. The vacuum pyrolysis is carried out at a temperature in the range of about 450.degree. to about 650.degree. C., under a subatmospheric pressure in the range of about 50 to about 200 mm Hg so as to thermally decompose and substantially completely vaporize organic matter adhered to the metals. At least one metal is separated from the solid residue, the metal being recovered in nonoxidized and substantially carbon-free form suitable for direct recycling.

Abstract: In a method for oil-extracting treatment of wastes for extracting oil by heating wastes contained in a waste containing chamber in a manner to be shut off from air, an inert gas is injected into the waste containing chamber after termination of thermal decomposition of the wastes to force out the combustible gas within said waste containing chamber and said waste containing chamber is then opened, so as to prevent an explosion due to mixing of the residual combustible gas within the waste containing chamber and air after the termination of thermal decomposition of the wastes.

Abstract: A plant for treating industrial and/or urban waste includes a stage for drying of the waste, followed by a stage for effecting thermolysis of the dried waste and a stage for effecting recovery of the solids and gases resulting from the thermolysis. Thermolysis of the waste is effected in a reactor by indirect heat exchange with combustion gases and drying gases for drying of the waste are subsequently treated to remove vapor materials and then recycled to a gas generator for generating the drying gases. Additionally the plant includes a stage for effecting dechlorination of the solids resulting from the thermolysis by washing the solids with an aqueous liquid, as well as a stage of separating the wash solids and the resulting wash liquid.

Abstract: A method for generating, from refuse or refuse in combination with coal, a fuel gas suited for public utility purposes wherein refuse and coal can be introduced into the process in any proportion one to the other. The method provides the steps of subjecting the refuse to allothermal low-temperature carbonization, if desired in combination with coal, burning the gasification residue, purifying the crude gas and conditioning the pure gas for public utility purposes.

Abstract: Apparatus for the production of charcoal by the comingling of a source of wood and ground sludge where the sludge is received from a paper making plant as wet sludge, grinding the wet sludge to a desired reduction, feeding the ground sludge into a furnace where it is comingled with wood, and circulating the furnace hot gas exhaust back through the grinding of the wet sludge to initiate the drying thereof.

Abstract: A process and apparatus for the continuous pyrolytic decomposition of a feed material having an organic and an inorganic component and recovery of the inorganic component, carbon-free, for reuse in essentially the same material as from which it originally emanated inter alia. The apparatus includes a reactor assembly for receiving and pyrolytically decomposing the organic component of the feed material. The reactor assembly includes a screw-type conveyer assembly wherein the flights which convey the residue through a housing having openings therein to allow gaseous decomposition products to pass therethrough to preclude pressurization of the housing by the decomposition products.

Abstract: A process and apparatus for the continuous pyrolitic decomposition of a feed material having an organic and an inorganic component and recovery of the inorganic component, carbon-free, for reuse in essentially the same material as from which it originally emanated inter alia. The apparatus includes a reactor assembly for receiving and pyrolitically decomposing the organic component of the feed material. The reactor assembly includes a screw-type conveyor assembly wherein the flights which convey the residue through a housing have openings therein to allow gaseous decomposition products to pass therethrough to preclude pressurization of the housing by the decomposition products. The inorganic residue has carbon thereon and may be cooled to an oxidation temperature in a non-oxidizing manner in a first cooling assembly.

Abstract: The macromolecular waste (which is not itself susceptible to microwave heating and may be, for example, plastics or polychlorinated biphenyl) is mixed (B) with pulverulent carbonaceous material, which comprises elemental carbon or is degradable by microwave irradiation to elemental carbon (such as waste tire material). The mix is subjected to microwave irradiation (C) in an inert atmosphere to cause pyrolysis of the plastics. Preferably part of the resulting solids is recycled to the microwave zone (C).

Abstract: Pyrolyzate oil is made amendable to hydrotreatment without substantial coking problems by means of pre-treatment with hydrogen at temperatures in the range of 250.degree. to 300.degree. C.