Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
  • C10G1/08—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal with moving catalysts

Definitions

• the present invention relates to an i nproved process for the pyrolysis of carbonous materials, such as coal, to produce liquid and gaseous products, by the use of iron and/or zinc soluble salts prior to pyrolysis.
• Pyrolysis of coal to yield liquids and char is an area of technology which has the potential of leading the way to a successful national synfuels program.
• the major limitations of present coal pyrolysis technology are the low quality of simple pyrolysis liquids combined with high sulfur content. Even when a coal in relatively low sulfur content is employed to reduce the need for hydrotreating, the product is generally low in yield and has stability problems.
• pyrolysis in the presence of hydrogen is advantageously combined, under certain conditions, to give increased yields and more stable liquid products than those by use of pyrolysis processes conventionally known.
• a process for converting carbonous materials . selected from subbituminous coal, oil-shale, lignite and peat, to liquid and gaseous product.s comprising: (a) impregnating the carbonous material with one or more water soluble salts of iron and/or zinc; (b) treating the impregnated material in such a way as to precipitate, into the structure of the material, the metal of the soluble salt as its oxide or in a form which can be readily converted to its oxide by decomposition; and (c) pyrolyzing the treated impregnated material in the presence of hydrogen, at a temperature from about 400°C to about 700°C, and at gas residence times of less than about 30 seconds and solids residence times of from about 5 to 100 minutes.
• subbituminous coal or oil-shale is impregnated with iron sulfate, treated with sodium carbonate, and pyrolyzed at a temperature of about 550°C.
• coal or oil shale may be treated according to the present invention, although for coal it is preferred to treat only the lower rank coals such as, subbituminous coal, lignite, and peat; of course, other similar solid carbonous materials may also be employed.
• Such coals usually have the following character: carbon content ranging from about 55 to 88 wt. %, hydrogen content ranging from about 3.8 to 6.2 wt. %, oxygen content ranging from about 2.6 to 33 wt. % (MAF basis), and a H/C ratio from about 0.3 to 1.1.
• oil shales particularly those with high aromatic content, can be treated in accordance with the present invention.
• the carbonous material have as high a surface area as possible; although, it is not economically justifiable to pulverize it to a very fine powder. Consequently, it is desirable to expose as much of the material's surface area as possible without losing material as dust or fines or as the economics of grinding or process equipment may dictate.
• the material will be ground to a finely divided state and will contain a majority of,particles less than about 4 mesh, U.S. Sieve Size.
• the coal may be dried by conventional drying techniques, for example, heating to a temperature of about 100°C to 110°C.
• the carbonous material after grinding, is impregnated with a water soluble salt of a metal selected from iron and zinc by forming a slurry of coal and salt solution.
• a water soluble salt of a metal selected from iron and zinc by forming a slurry of coal and salt solution.
• water soluble salts suitable for use herein include iron chloride, iron sulfate, iron nitrate, zinc chloride and zinc sulfate. More preferred is iron sulfate.
• the salt solution is prepared by dissolving enough of the salt in water to result in at least a O.Ol M solution. Preferably a 0.lM solution is employed. It is desirable to dissolve the salt in enough polar solvent, preferably water so as to have about the same weight of water as the weight of carbonous material.
• the salt solution and carbonous material are slurried at a temperature from about room temperature (20°C) to about the boiling point of the solution. Generally. about 1 part of salt solution by weight is employed for each part.of carbonous material by weight.
• an effective amount of time means at least that amount of time needed to ensure substantially'total impregnation of the salt solution into the structure of the carbonous material. This amount of time is primarily dependent on the moisture content of the carbonous material. For example, impregnation of dry coal is achieved in a matter of minutes whereas impregnation of wet coal may require about 24 hours owing to transfer problems of the salt into the wet coal structure.
• the carbonous material is impregnated with the water soluble salt, it is treated in such a way as to cause precipitation, into the structure of the carbonous material, of the metal of the soluble salt used for impregnation.
• the precipitated metal will nest likely be in a well dispersed fonn, preferably as its oxide, or in a form which can be readily converted to its oxide by decomposition.
• Non-limiting examples of such methods which can be employed herein, to cause precipitation include: (a) raising the pH of the slurry to an effective pH to cause precipitation of the metal as a hydroxide or hydrated oxide; (b) introducing an anion into the slurry in form of another soluble salt which will produce the oxide of the metal or which will produce a form which can readily be converted to its oxide by decomposition, for example at the pyrolysis conditions employed herein.
• Non-limiting examples of cations of which this other anion producing soluble salt is comprised include sodium, ammonium and potassium. Considerations which should be kept in mind when choosing such other salt as well as any other aqent used to cause precipitation: (a) not adversely affect the pyrolysis products or their evolution and recovery, (b) be economically feasible, and (c) be non-toxic.
• an appropriate base is introduced into the slurry.
• bases suitable for being employed herein include ammonia, a caustic solution, and an organic base.
• the pH to which the impregnated carbonous material slurry would have to be raised to affect precipitation would vary depending upon the solubility product of the salts employed. Generally a pH in excess of about 11 will precipitate most salts.
• the anion chosen is one which will produce an insoluble form of the metal of the soluble salt employed herein for impregnating.
• Such an insoluble form should be one which is its oxide already or one which can be readily decomposed, under the pyrolysis conditions employed herein, to its oxide.
• anions suitable for such purposes include carbonates, bicarbonates, hydroxides, etc.
• the treated carbonous material After treating, so as to precipitate the metal in a well-dispersed form, it is preferred to dry the treated carbonous material. Any conventional drying means may be employed.
• the treated and preferably dried carbonous material is then subjected to pyrolysis at temperatures from about 400°C to about 700°C, preferably from about 450°C to 600°C.
• the pyrolysis is performed in the presence of hydrogen, generally at hydrogen pressures from about 500 to 2500 psi. Any excess hydrogen, of course, will be recycled.
• the pyrolysis is performed at relatively short gas and long solids residence times. That is, the gas residence time should be less than about 30 seconds, preferably less than 10 seconds and the solids residence times should be from about 5 to 100 minutes, preferably from about 10 to 30 minutes.
• Non-limiting examples of reactors suitable for use herein include fixed and fluid bed.
• the primary constraint on the reactor employed is to minimize contact with the solid phase with hydrogen at reaction temperatures.
• 150g of this dried and treated coal was pyrolyzed in a fixed bed type reactor, by heating it at a rate of 6°C/min. to 600°C-and holding it at about that temperature for 20 minutes.
• the fixed bed was an annular configuration having the dimensions of 4" ID x 4 1/2" O D x 6" deep, and had a hydrogen flow rate of 2 standard cu. ft/min.
• the total liquid product collected was 39.3 wt. % of the dry coal.
• Example 1 The procedure of Example 1 was followed except the coal was not treated with salt solutions..After pyrolysis the untreated coal produced a liquid product of 30.2 wt. % based on the weight of the dry coal.
• Example 1 The procedure of Example 1 above was followed except ferrous ammonium sulfate was substituted for zinc chloride and 1% by weight solution of sodium carbonate was employed to precipitate ferrous hydroxide into the coal structure.
• the iron content of the impregnating solution was 0.14 wt. %.
• Pyrolysis was carried out by heating the sample, under 400 psi hydrogen pressure, to 300°C rapidly then utilizing a heating rate of 100°C/30 min., to 500°C.
• Example 2 The procedure of Example 2 above was followed except the coal was not treated with the salt solutions before pyrolysis. After pyrolysis, it was found that 43.0 wt. % based on the weight of the dry coal, had been converted to volatile products.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Catalysts (AREA)

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Citations (3)

• 1981
  • 1981-11-05 CA CA000389513A patent/CA1164382A/fr not_active Expired
  • 1981-12-23 EP EP81306071A patent/EP0055600A3/fr not_active Withdrawn
  • 1981-12-24 AU AU79036/81A patent/AU7903681A/en not_active Abandoned
  • 1981-12-28 JP JP56210078A patent/JPS57133190A/ja active Pending
  • 1981-12-28 IL IL64660A patent/IL64660A0/xx unknown
  • 1981-12-28 BR BR8108406A patent/BR8108406A/pt unknown
  • 1981-12-29 ZA ZA818969A patent/ZA818969B/xx unknown

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