WO2000029365A2 - Preparation de polyoxymethylene dimethylethers par la conversion catalytique activee par acide de methanol avec du formaldehyde - Google Patents

Preparation de polyoxymethylene dimethylethers par la conversion catalytique activee par acide de methanol avec du formaldehyde Download PDF

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Publication number
WO2000029365A2
WO2000029365A2 PCT/US1999/020751 US9920751W WO0029365A2 WO 2000029365 A2 WO2000029365 A2 WO 2000029365A2 US 9920751 W US9920751 W US 9920751W WO 0029365 A2 WO0029365 A2 WO 0029365A2
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Prior art keywords
formaldehyde
methanol
mixture
catalyst
dimethyl ether
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PCT/US1999/020751
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English (en)
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WO2000029365A3 (fr
Inventor
Gary P. Hagen
Michael J. Spangler
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Bp Amoco Corporation
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Priority claimed from US09/190,699 external-priority patent/US6265528B1/en
Application filed by Bp Amoco Corporation filed Critical Bp Amoco Corporation
Priority to AU60324/99A priority Critical patent/AU6032499A/en
Publication of WO2000029365A2 publication Critical patent/WO2000029365A2/fr
Publication of WO2000029365A3 publication Critical patent/WO2000029365A3/fr

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L10/00—Use of additives to fuels or fires for particular purposes
    • C10L10/08—Use of additives to fuels or fires for particular purposes for improving lubricity; for reducing wear
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
    • C07C41/48—Preparation of compounds having groups
    • C07C41/50—Preparation of compounds having groups by reactions producing groups
    • C07C41/56—Preparation of compounds having groups by reactions producing groups by condensation of aldehydes, paraformaldehyde, or ketones
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L10/00—Use of additives to fuels or fires for particular purposes
    • C10L10/02—Use of additives to fuels or fires for particular purposes for reducing smoke development
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency

Definitions

  • the present invention relates to production of organic compounds, particularly polyoxymethylene dimethyl ethers, which are suitable components for blending into fuel having improved qualities for use in diesel engines. More specifically, it relates to providing a feedstream comprising methanol, formaldehyde and a soluble condensation promoting component capable of activating a heterogeneous acidic catalyst, and heating this feedstream with the heterogeneous acidic catalyst in a catalytic distillation column to convert methanol and formaldehyde present to methylal and higher polyoxymethylene dimethyl ethers and separate the methylal from the higher polyoxymethylene dimethyl ethers.
  • the catalytic distillation column has a section containing an anion exchange resin whereby an essentially acid-free product is obtained which can be used directly as a blending component, or fractionated, as by further distillation, to provide more suitable components for blending into diesel fuel.
  • Integrated processes of the invention also provide their own source of formaldehyde.
  • the source of formaldehyde is an un-purified liquid stream derived from a mixture formed by oxidative dehydrogenation (oxy- dehydrogenation) of methanol, dimethyl ether and mixtures thereof using, for example, a catalyst based silver.
  • methane is converted to methanol, and dimethyl ether is subsequently manufactured from methanol by passing a mixed vapor containing methanol and water over an alumina catalyst, as described in an article by Hutchings in New Scientist (3 July 1986) 35.
  • Formaldehyde is a very important intermediate compound in the chemical industry.
  • the extreme reactivity of the formaldehyde carbonyl group and the nature of the molecule as a basic building block has made formaldehyde an important feedstock for a wide variety of industrially important chemical compounds.
  • formaldehyde has found its largest volume of application in the manufacture of phenol - formaldehyde resins, urea-formaldehyde resins and other polymers. Pure formaldehyde is quite uncommon since it polymerizes readily. It was usually obtained as an aqueous solution such as formalin, which contains only about 40 percent formaldehyde. However, more recently, formaldehyde is usually transported as an item of commerce in concentrations of 37 to 50 percent by weight.
  • paraformaldehyde A solid source of formaldehyde called paraformaldehyde is also commercially available. Because of the reactivity of formaldehyde, its handling and separation require special attention. It is a gas above -19°C and is flammable or explosive in air at concentrations of about 7 to about 12 mol percent. Formaldehyde polymerizes with itself at temperatures below 100°C and more rapidly when water vapor or impurities are present. Since formaldehyde is usually transported in aqueous solutions of 50 percent by weight or lower concentration, producers have tended to locate close to markets and to ship the methanol raw material, which has a smaller volume.
  • a catalytic distillation structure which comprises a catalyst component associated intimately with or surrounded by a resilient component, which component is comprised of at least 70 vol. percent open space for providing a matrix of substantially open space.
  • resilient component are open-mesh, knitted, stainless wire (demister wire or an expanded aluminum); open-mesh, knitted, polymeric filaments of nylon, Teflon, etc.; and highly-open structure foamed material (reticulated polyurethane).
  • the middle portion of the distillation column was furnished with stages from which the liquid components were withdrawn and pumped to the reactor units, which contained solid acid catalyst.
  • the reactive solutions containing the resulting methylal were fed to the distillation column, where methylal was distilled as the overhead product.
  • Polyoxymethylene dimethyl ethers are the best known members of the dialkyl ether polymers of formaldehyde. While diethyl and dipropyl polyoxymethylene ethers have been prepared, major attention has been given to the dimethyl ether polymers. Polyoxymethylene dimethyl ethers make up a homologous series of polyoxymethylene glycol derivatives having the structure represented by use of the type formula indicated below:
  • acetals closely related to methylal, CH 3 OCH 2 OCH 3 , which may be regarded as the parent member of the group in which n of the type formula equals 1. They are synthesized by the action of methanol on aqueous formaldehyde or polyoxymethylene glycols in the presence of an acidic catalyst just as methylal is produced. On hydrolysis they are converted to formaldehyde and methanol. Like other acetals, they possess a high degree of chemical stability. They are not readily hydrolyzed under neutral or alkaline conditions, but are attacked by even relatively dilute acids. They are more stable than the polyoxymethylene diacetates.
  • Polyoxymethylene dimethyl ethers are prepared in laboratory scale by heating polyoxymethylene glycols or paraformaldehyde with methanol in the presence ⁇ of a trace of sulfuric or hydrochloric acid in a sealed tube for 15 hours at 150°C, or for a shorter time (12 hours) at 165° to 180°C.
  • Considerable pressure is caused by decomposition reactions, which produce carbon oxides, and by formation of some dimethyl ether.
  • the average molecular weight of the ether products increases with the ratio of paraformaldehyde or polyoxymethylene to methanol in the charge.
  • a high polymer is obtained with a 6 to 1 ratio of formaldehyde (as polymer) to methanol.
  • the n value of the type formula CH3 ⁇ (CH2 ⁇ )nCH3 is greater than 100, generally in the range of
  • the products are purified by washing with sodium sulfite solution, which does not dissolve the true dimethyl ethers, and may then be fractionated by fractional crystallization from various solvents.
  • Crystalline aluminosilicates are the most prevalent and, as described in the patent literature and in the published journals, are designated by letters or other convenient symbols.
  • Moulton and David W. Naegeli reported blending a mixture of alkoxy-terminated poly-oxymethylenes, having a varied mixture of molecular weights, with diesel fuel to form an improved fuel for autoignition engines.
  • Two mixtures were produced by reacting paraformaldehyde with (i) methanol or (ii) methylal in a closed system for up to 7 hours and at temperatures of 150° to 240°C and pressures of 300 psi to 1,000 psi to form a product containing methoxy-terminated poly-oxymethylenes having a molecular weight of from about 80 to about 350 (polyoxymethylene dimethyl ethers).
  • a 1.6 liter cylindrical reactor was loaded with a mixture of methanol and paraformaldehyde, in molar ratio of about 1 mole methanol to 3 moles paraformaldehyde, and in a second preparation, methylal (dimethoxymethane) and paraformaldehyde were combined in a molar ratio of about 1 mole methylal to about 5 moles paraformaldehyde.
  • methylal (dimethoxymethane) and paraformaldehyde were combined in a molar ratio of about 1 mole methylal to about 5 moles paraformaldehyde.
  • a small amount of formic acid about 0.1 percent by weight of the total reactants, was added as a catalyst.
  • the same temperatures, pressures and reaction times are maintained as in the first. Disadvantages of these products include the presence of formic acid and thermal instability of methoxy-terminated poly- oxymethylenes under ambient pressure and acidic conditions.
  • the base diesel fuel when blended with such mixtures in a volume ratio of from about 2 to about 5 parts diesel fuel to 1 part of the total mixture, is said to provide a higher- quality fuel having significantly improved lubricity and reduced smoke formation without degradation of the cetane number or smoke formation characteristics as compared to the base diesel fuel.
  • This invention is directed to overcoming the problems set forth above in order to provide Diesel fuel having improved qualities. It is desirable to have a method of producing a high quality diesel fuel that has better fuel lubricity than conventional low-sulfur, low-aromatics diesel fuels, yet has comparable ignition quality and smoke generation characteristics. It is also desirable to have a method of producing such fuel which contains an additional blended component that is soluble in diesel fuel and has no carbon-to-carbon bonds. Furthermore, it is desirable to have such a fuel wherein the concentration of gums and other undesirable products is reduced.
  • continuous processes of this invention comprise providing a feedstream comprising methanol, formaldehyde and a soluble condensation promoting component capable of activating a heterogeneous acidic catalyst, and heating the feedstream with the heterogeneous acidic catalyst under conditions of reaction sufficient to form an effluent of condensation comprising water, methanol and one or more polyoxymethylene dimethyl ethers having a structure represented by the type formula CH3 ⁇ (CH2 ⁇ )nCH3
  • n is a number from 1 to about 10.
  • Suitable soluble condensation promoting components capable of activating the heterogeneous acidic catalyst comprises at least one member of the group consisting of low boiling, monobasic organic acids, preferable the group consists of formic acid and acetic acid. More preferable soluble condensation promoting component capable of activating the heterogeneous acidic catalyst comprises at least formic acid .
  • the heating of the feedstream with the acidic catalyst is carried out at in at least one catalytic distillation column having internal and/or external stages of contact with the acidic catalyst and internal zones to separate methylal from higher polyoxymethylene dimethyl ethers.
  • at least a liquid portion of the effluent containing polyoxymethylene dimethyl ethers is contacted with an anion exchange resin disposed within a section of the distillation column below the stages of contact with the acidic catalyst to form an essentially acid-free mixture.
  • the essentially acid-free mixture of polyoxymethylene dimethyl ethers is fractionated within a section of the distillation column below the stages of contact with the acidic catalyst to provide an aqueous side- stream which is withdrawn from the distillation column, and an essentially water- free mixture of polyoxymethylene dimethyl ethers having values of n greater than 1 which mixture is withdrawn from the distillation column near its bottom.
  • a source of methanol can be admixed with the feedstream, and/or into the stages of contact with the acidic catalyst.
  • Suitable acidic catalysts include at least one member of the group consisting of bentonites, montmorillonites, cation-exchange resins, and sulfonated fluoroalkylene resin derivatives, preferably comprises a sulfonated tetrafluoroethylene resin derivative.
  • a preferred class of acidic catalysts comprises at least one cation-exchange resin of the group consisting- of styrene- divinylbenzene copolymers, acrylic acid-divinylbenzene copolymers, and methacrylic acid-divinylbenzene copolymers.
  • the heating of the bottom stream with the acidic catalyst employs at least one distillation column with internal and/or external stages of contact with the acidic catalyst.
  • Another aspect this invention is an integrated process which further comprises formation of the feedstream by a process comprising continuously contacting methanol in the vapor phase with a catalytically effective amount of a catalyst consisting of copper, zinc and a member selected from the group consisting of sulfur, selenium and tellurium as catalyst components at elevated temperatures to form a gaseous dehydrogenation mixture comprising formaldehyde, methanol, dihydrogen and carbon monoxide; cooling the gaseous dehydrogenation mixture to predominantly condense methanol, and adsorb formaldehyde therein; and separating the resulting liquid source of formaldehyde from a mixture comprising dihydrogen and carbon monoxide.
  • a catalyst consisting of copper, zinc and a member selected from the group consisting of sulfur, selenium and tellurium as catalyst components at elevated temperatures to form a gaseous dehydrogenation mixture comprising formaldehyde, methanol, dihydrogen and carbon monoxide
  • cooling the gaseous dehydrogenation mixture to
  • the resulting liquid source of formaldehyde contains about 30 to about 85 percent by weight formaldehyde in methanol solution containing less than 5 percent water, and is recovered by using at least one continuous adsorption column with cooling to temperatures in a range downward from about 100°C to 25°C.
  • FIGURE 1 to FIGURE 4 are schematic flow diagrams depicting a preferred aspects of the present invention for continuous catalytic production of polyoxymethylene dimethyl ethers by chemical conversion of methanol and formaldehyde in which a feedstream comprising a soluble condensation promoting component capable of activating a heterogeneous acidic catalyst is heated with the heterogeneous acidic catalyst in a catalytic distillation column with internal stages of contact.
  • a liquid portion of the effluent of condensation, containing polyoxymethylene dimethyl ethers is contacted with an anion exchange resin disposed within a section of the distillation column below the stages of contact with the acidic catalyst to form an essentially acid-free mixture, and fractionated to provide suitable components for blending into diesel fuel.
  • the feedstream in the integrated process depicted in FIGURE 1 is a stream of formaldehyde in methanol derived from dehydrogenation of dimethyl ether.
  • FIGURE 2 is a stream of formaldehyde in methanol derived from dehydrogenation of methanol.
  • the feedstream in the integrated process depicted in FIGURE 3 is a stream of aqueous formaldehyde in methanol derived from oxidation of dimethyl ether.
  • recycle gas from the formaldehyde absorber is combined with air, mixed with dimethyl ether, preheated against reactor product, and then fed to the formaldehyde reactor.
  • the feedstream in the integrated process depicted in FIGURE 4 is a stream of aqueous formaldehyde in methanol derived from oxidative dehydrogenation of dimethyl ether.
  • recycle gas from the formaldehyde absorber is combined with air, mixed with dimethyl ether, preheated against reactor product, and then fed to the formaldehyde reactor.
  • the improved processes of the present invention employ a feedstream comprising methanol, formaldehyde and a soluble condensation promoting component capable of activating a heterogeneous acidic catalyst.
  • Suitable component ⁇ include any acidic compound soluble in the feedstream, preferably an organic compound soluble in a feedstream of about 30 to about 85 percent by weight formaldehyde in methanol solution containing less than 5 percent water.
  • a preferred class of condensation promoting components capable of activating a heterogeneous acidic catalyst includes members of the group consisting of low boiling, monobasic organic acids, more preferably acetic acid or formic acid.
  • effluent mixtures can comprise water, methanol, formaldehyde, methylal and other polyoxymethylene dimethyl ethers having a structure represented by the type formula
  • n is a number ranging between 1 and about 15, preferably between 1 and about 10. More preferably the mixture contains a plurality of polyoxymethylene dimethyl ethers having values of n are in a range from 2 to about 7.
  • Conditions of reaction include temperatures in a range from about 50° to about 300°C, preferably in a range from about 150° to about 250°C.
  • Sources of dimethyl ether useful herein are predominantly dimethyl ether, preferably at least about 80 percent dimethyl ether by weight, and more preferably about 90 percent dimethyl ether by weight.
  • Suitable dimethyl ether sources may contain other oxygen containing compounds such as alkanol and/or water, preferably not more than about 20 percent methanol and/or water by weight, and more preferably not more than about 15 percent methanol and/or water by weight.
  • the ratio of formaldehyde to methanol in the feedstreams is any mole ratio which results in the production of the desired oxygenated organic compound.
  • the ratio of formaldehyde to methanol is preferably between about 10: 1 and about 1 : 10 moles.
  • the ratio of formaldehyde to methanol is preferably between about 5: 1 and about 1:5 moles. More preferably, the ratio of formaldehyde to methanol is between about 2: 1 and about 1:2 moles.
  • the feedstream comprising methanol, formaldehyde and a soluble condensation promoting component capable of activating a heterogeneous acidic catalyst is heated in a catalytic distillation column with an acidic catalyst, which is heterogeneous to the feedstream, under conditions of reaction sufficient to convert formaldehyde and methanol present to methylal and higher polyoxymethylene dimethyl ethers.
  • the solid acidic catalyst for use in the present invention include cation exchange resins, sulfonated fluoroalkylene resin derivatives, and crystalline aluminosilicates.
  • Cation exchange resins that can be used in the present invention may be carboxylated or sulfonated derivatives, but sulfonated derivatives are preferred because of the high reaction yield that can be attained.
  • Ion exchange resins that can be used may be gel-type cation exchange resins or macroporous (macroreticular) cation-exchange resins, but the latter as exemplified by Amberlite 200C of Organc Co, Ltd. and Lewalit SP112 of Bayer A.G. are preferred because of the high reaction yield that can be attained.
  • useful ion exchange resins include a styrene-divinylbenzene copolymer, an acrylic acid-divinylbenzene copolymer, a methacrylic acid- divinylbenzene copolymer, etc.
  • a sulfonated tetrafluoroethylene resin derivative (trade name, Naflon H) is preferably used as a sulfonated fluoroalkylene resin derivative.
  • the ratio of formaldehyde to dimethyl ether in the feedstreams is any mole ratio which results in the production of the desired oxygenated organic compound.
  • the ratio of formaldehyde to dimethyl ether is preferably between about 10: 1 and about 1:10 moles.
  • the ratio of formaldehyde to dimethyl ether is preferably between about 5:1 and about 1 :5 moles. More preferably, the ratio of formaldehyde to dimethyl ether is between about 2: 1 and about 1:2 moles.
  • a source of formaldehyde is formed by subjecting methanol in the vapor phase to dehydrogenation in the presence of a catalytically effective amount of a catalyst preferably containing copper and zinc as well as tellurium and/or selenium and/or sulfur, if appropriate in the form of the oxides.
  • Oxide catalysts which can contain copper, zinc and tellurium, are particularly useful.
  • One class of preferred catalysts comprises copper, zinc and selenium or tellurium as catalyst components in an atomic ratios of 1 :0.01- 0.5:0.005-0.5, preferably 1 :0.05-0.5:0.01-0.4, with the proviso that the amount of zinc is at least equal to the amount of selenium or tellurium present.
  • the catalyst used in the present invention may be prepared by any one of conventional procedures known to those skilled in the art, for example, precipitation method, thermal decomposition method, or deposition and drying method. Any of these procedures may be properly selected based on the raw material to be used.
  • Suitable raw materials for catalyst useful in the present invention include a copper salt of a mineral acid such as copper nitrate, copper chloride, copper sulfate, copper sulfite, copper hydroxide, copper oxide, basic copper carbonate, metallic copper, and the like as a source of copper; a zinc salt of a mineral acid such as zinc nitrate, zinc chloride, zinc sulfate, zinc sulfite, zinc hydroxide, zinc oxide, metallic zinc and the like as a source of zinc; and selenic acid, selenious acid, selenium oxide, or metallic selenium and the like as a source of selenium.
  • zinc selenide, zinc selenate, zinc selenite, and the like may be used as a source of both zinc and selenium
  • copper selenide may be used as a source of both copper and selenium.
  • Such catalysts can be prepared, for example, by kneading copper oxide with zinc oxide and tellurium dioxide (and/or selenium dioxide and/or ammonium sulfate) in the presence of water, drying the mixture at 130° C. and then pressing it to form pills, with or without admixture of a carrier.
  • Suitable raw materials may be formed to a particle having a desired shape which may be tablet, sphere or the like and the average diameter of the particles thus formed should be more than 1 mm, preferably 2 to 5 mm.
  • Catalyst particles are then reduced in a reductive atmosphere, for example, in two steps, first at a temperature of 100° to 300°C, preferably 150° to 250°C for more than 0.2 hour, preferably 0.5 to 1 hour and then at the temperature of 500° to 750°C, preferably 600° to 700°C for more than 0.1 hour, preferably 0.5 to 1 hour.
  • the copper oxide is completely or partially reduced to metallic copper, during use, by the hydrogen formed on dehydrogenation of methanol.
  • the process may be carried out with the catalysts in the form of a fixed bed in the reaction vessel, for example a tubular reactor.
  • a fluidized bed can also be used.
  • methanol may be used alone, or methanol and dimethyl ether can be used in admixture with each other to produce formaldehyde.
  • FIGURE 1 In integrated processes of this invention a feedstream comprising methanol, formaldehyde and a soluble condensation promoting component capable of activating a heterogeneous acidic catalyst is provided by contacting dimethyl ether in the vapor phase with a catalytically effective amount of a catalyst consisting of copper, zinc and a member selected from the group consisting of sulfur, selenium and tellurium as catalyst components at elevated temperatures to form a gaseous dehydrogenation mixture comprising formaldehyde, formic acid, dimethyl ether, dihydrogen and carbon monoxide; cooling the gaseous dehydrogenation mixture with an adsorption liquid and adsorbing formaldehyde and formic acid therein; and separating the resulting liquid source of formaldehyde from a gaseous mixture comprising dihydrogen and carbon monoxide.
  • a catalyst consisting of copper, zinc and a member selected from the group consisting of sulfur, selenium and tellurium as catalyst components at elevated temperatures to form a gaseous
  • a mixture containing dimethyl ether in substantially liquid form is unloaded, for example from a road tanker (not shown), into dimethyl ether storage vessel 12 which supplies charge pump 1 4 through conduit 1 3 .
  • Charge pump 1 4 transfers the liquid dimethyl ether through conduit 16 into manifold 92 which is in flow communication with heat exchanger 1 04 and formaldehyde reactor 90 through conduit 94.
  • Formaldehyde reactor 90 contains particulate dehydrogenation catalyst disposed in a plurality of tubes of a vertical heat exchanger which is maintained at elevated temperatures by circulation of heating fluid to the shell side of formaldehyde reactor 90 through conduit 88 from furnace 80. Heating fluid is returned to furnace 80 through conduits 96 and 86 by means of pump 84. Natural gas or other suitable fuel is supplied to furnace fuel manifold 82 through conduit 74 from fuel supply 72 . As described below, at least a portion of the co- product hydrogen is used as fuel for combustion with air in furnace 80.
  • CuZnTeO/Al2 ⁇ 3 or CuZnSeO/AhOg catalyzes the conversion of dimethyl ether to formaldehyde by a reversible dehydrogenation reaction at temperatures in a range from about 500° to 750°, preferably in a range from about 600° to 700°C:
  • Gaseous effluent from formaldehyde reactor 90 is transferred through conduit 102 , cooled against the reactor feedstream in exchanger 104 and then passed through conduit 106 into an adsorption tower 100 where formaldehyde and dimethyl ether are separated from a mixture of gaseous co- products including hydrogen, methane, and oxides of carbon.
  • Adsorption tower 100 contains a high efficiency packing or other means for contacting counter-currently the gaseous stream with an adsorption liquid.
  • Formaldehyde in methanol from the bottom of the adsorption tower is circulated in a pump-around to a lower section of the tower through conduits 1 12 and 1 1 6 , cooler 120 , and conduit 1 1 8 by means of pump 1 1 4 .
  • Methanol is supplied to an upper section of the adsorption separation tower through conduit 122 by means of pump 48.
  • Overhead temperatures are in a range of about 15° to about 55°C, preferably about 20° to about 40°C.
  • a gaseous overhead stream including hydrogen, methane, and oxides of carbon is transferred through conduit 1 24 and into furnace fuel manifold 82 by means of blower 126.
  • additional fuel such as natural gas is supplied to manifold 82 from a suitable fuel source 72 through conduit 74.
  • Formaldehyde solution from the adsorption tower is generally from about 30 to about 85 percent by weight formaldehyde in methanol solution containing less than about 5 percent water.
  • effluent from the adsorption tower is a valuable product in itself.
  • a portion of the stream can optionally be diverted from adsorption tower 100 for delivery to a destination (not shown) where the stream may subsequently be separated to recover, for example, formaldehyde and methanol and/or dimethyl ether.
  • the stream can alternatively be utilized as a source of feed stock for chemical manufacturing.
  • the adsorption liquid containing formaldehyde, formic acid and dimethyl ether in methanol is transferred from adsorption tower 100 through conduits 1 12 and 18 , by means of pump 1 14 , and into ether recovery column 30 , where unreacted dimethyl ether is separated from the effluent stream to form a resulting liquid mixture of formaldehyde, formic acid and methanol.
  • a dimethyl ether fraction is taken overhead through conduit 32 and into condenser 34 where a liquid condensate is formed.
  • a suitable portion of the liquid condensate is refluxed into column 30 through conduits 35 and 36 while another portion of the condensate is supplied to manifold " 92 through conduit, 37 and 39 by means of pump 38.
  • Conduit 28 supplies pump 40 with liquid from the bottom of ether recovery column 30.
  • a suitable portion of the liquid stream from the bottom of column 30 is transferred through conduits 41 and 42 , by means of pump 40 , and into reboiler 43 which is in flow communication with the bottom of the column through conduit 44.
  • a liquid stream from the bottom of column 30 is transferred through conduit 45 into reactive distillation column 50 , where simultaneous chemical reaction and multicomponent distillation are carried out coextensively in the same high efficiency, continuous separation apparatus.
  • a stream containing methanol from storage vessel 46 maybe admixed with the feedstream, and/or into the stages of contact with the acidic catalyst of the reactive distillation column 50.
  • Charge pump 48 can transfer methanol into the reactive distillation column 50 through conduits 47 and 49.
  • Solid acidic catalyst is present in the reactive distillation column 50 to allow solutions containing water, methanol, formaldehyde, methylal and one or more other polyoxymethylene dimethyl ethers to be brought into solid-liquid contact counter- currently with the catalyst to form products including methylal and higher molecular weight polyoxymethylene dimethyl ethers. More volatile reaction products are taken overhead from the high efficiency separation apparatus, whereas water and less volatile reaction products are carried down the high efficiency separation apparatus.
  • the overhead vapor stream from reactive distillation column 50 is transferred through conduit 52 into condenser 54.
  • a suitable portion of condensate from condenser 54 is refluxed into reactive distillation column 50 through conduits 55 and 56.
  • a product stream containing methylal is transferred through conduit 57 to product storage (not shown).
  • Conduit 59 supplies pump 60 with liquid containing higher molecular weight polyoxymethylene dimethyl ethers from the bottom of column 50.
  • a suitable portion of liquid from the bottom of column 50 is transferred, by means of pump 60 , through conduits 62 and 63 into reboiler 64 which is in flow communication with the bottom of the column by means of conduit 66.
  • a product stream containing higher molecular weight polyoxymethylene dimethyl ethers is transferred through conduit 68 to product storage (not shown).
  • product storage not shown.
  • an anion exchange resin is disposed within a section of the distillation column below the stages of contact with the acidic catalyst to form an essentially acid-free mixture.
  • An aqueous side stream containing low levels of unreacted formaldehyde and/or methanol is discharged from column 50 through conduit 58.
  • FIGURE 2 Still another preferred aspect of the invention is depicted schematically in FIGURE 2.
  • a feedstream comprising methanol, formaldehyde and a soluble condensation promoting component capable of activating a heterogeneous acidic catalyst is provided by contacting methanol in the vapor phase with a catalytically effective amount of a catalyst consisting of copper, zinc and a member selected from the group consisting of sulfur, selenium and tellurium as catalyst components at elevated temperatures to form a gaseous dehydrogenation mixture comprising formaldehyde, formic acid, dimethyl ether, dihydrogen and carbon monoxide; cooling the gaseous dehydrogenation mixture with an adsorption liquid and adsorbing formaldehyde and formic acid therein; and separating the resulting liquid source of formaldehyde from a gaseous mixture comprising dihydrogen and carbon monoxide.
  • a catalyst consisting of copper, zinc and a member selected from the group consisting of sulfur, selenium and tellurium as
  • gaseous methanol is dehydrogenated in the presence of catalytically effective amount of a catalyst consisting of copper, zinc and tellurium or selenium as catalyst components.
  • a catalyst consisting of copper, zinc and tellurium or selenium as catalyst components.
  • FIGURE 2 a mixture containing methanol in substantially liquid form is unloaded, for example from a road tanker (not shown), into methanol storage vessel 46 which supplies charge pump 48 through conduit 47.
  • Charge pump 48 transfers the liquid methanol through conduit 42 and conduit 92 which is in flow communication with heat exchanger 104 and formaldehyde reactor 90 through conduit 94.
  • Formaldehyde reactor 90 contains particulate dehydrogenation catalyst disposed in a plurality of tubes of a vertical heat exchanger which is maintained at temperatures from about 500° to 750°C by circulation of heating fluid to the shell side of formaldehyde reactor 90 through conduit 88 from furnace 80. Heating fluid is returned to furnace 80 through conduits 96 and 86 by means of pump 84. Natural gas or other suitable fuel is supplied to furnace fuel manifold 82 through conduit 81 from a suitable fuel source 83. As described below, at least a portion of the co-product hydrogen is used as fuel for combustion with air in furnace 80.
  • CuZnTeO or CuZnSeO catalyzes the conversion of methanol to formaldehyde by a reversible dehydrogenation reaction at temperatures in a range from about 500° to 750°, preferably in a range from about 600° to 700°C:
  • Gaseous effluent from formaldehyde reactor 90 is transferred through conduit 1 02 , cooled against the reactor feedstream in exchanger 104 and then passed through conduit 1 06 into a separation tower 1 00 where formaldehyde and methanol are separated from a mixture of gaseous co-products including hydrogen, methane, and oxides of carbon.
  • Adsorption tower 1 00 contains a high efficiency packing or other means for contacting counter- currently the gaseous stream with an adsorption liquid.
  • Adsorption liquid from the bottom of adsorption separation tower 1 00 is circulated in a pump-around on the adsorption tower through conduits 1 12 and 1 16 , cooler 120 , and conduit 1 1 8 by means of pump 1 14.
  • Methanol is diverted from conduit 42 , through conduit 44 to supply pump 1 14.
  • Overhead temperatures in separation tower 100 are in a range of about 15° to about 55°C, preferably about 30° to about 40°C.
  • a gaseous overhead stream including hydrogen, methane, and oxides of carbon is transferred through conduit 1 22 and into furnace fuel manifold 82 by means of blower 1 24.
  • additional fuel such as natural gas is supplied to manifold 82 through conduit 81 from a suitable fuel source 83 .
  • Formaldehyde solution from the adsorption tower is generally from about 30 to about 85 percent by weight formaldehyde in methanol solution containing less than about 5 percent water. It should be apparent that effluent from the adsorption tower is a valuable product in itself.
  • a portion of the stream can optionally be diverted from adsorption tower 1 00 for delivery to a destination (not shown) where the stream may subsequently be separated to recover, for example, formaldehyde and methanol and/or dimethyl ether.
  • the stream can alternatively be utilized as a source of feed stock for chemical manufacturing.
  • Adsorption liquid containing formaldehyde, formic acid and water in methanol is transferred from adsorption tower 1 00 through conduits 1 12 and 45 , by means of pump 1 1 4 , and into reactive distillation column 50.
  • Solid acidic catalyst is present in the reactive distillation column 50 to allow solutions containing water, methanol, formaldehyde, methylal and one or more other polyoxymethylene dimethyl ethers to be brought into solid-liquid contact counter-currently with the catalyst to form products including methylal and higher molecular weight polyoxymethylene dimethyl ethers. More volatile reaction products are taken overhead from the high efficiency separation apparatus, whereas water and less volatile reaction products are carried down the high efficiency separation apparatus.
  • the overhead vapor stream from reactive distillation column 50 is transferred through conduit 52 into condenser 54.
  • a suitable portion of condensate from condenser 54 is refluxed into reactive distillation column 50 through conduits 55 and 56.
  • a product stream containing methylal is transferred through conduit 57 to product storage (not shown).
  • Conduit 59 supplies pump 60 with liquid containing higher molecular weight polyoxymethylene dimethyl ethers from the bottom of column 50.
  • a suitable portion of liquid from the bottom of column 50 is transferred, by means of pump 60 , through conduits 62 and 63 into reboiler 64 which is in flow communication with the bottom of the column by means of conduit 66.
  • a product stream containing higher molecular weight polyoxymethylene dimethyl ethers is transferred through conduit 68 to product storage (not shown).
  • product storage not shown.
  • an anion exchange resin is disposed within a section of the distillation column below the stages of contact with the acidic catalyst to form an essentially acid-free mixture.
  • An aqueous side stream containing low levels of unreacted formaldehyde and/or methanol is discharged from column 50 through conduit 58.
  • FIGURE 3 Still another preferred aspect of the invention is depicted schematically in FIGURE 3.
  • a feedstream comprising methanol, formaldehyde and a soluble condensation promoting component capable of activating a heterogeneous acidic catalyst is provided by contacting dimethyl ether in the vapor phase with a catalytically effective amount of an oxidation promoting catalyst comprising tungsten oxide as an essential catalyst component at elevated temperatures to form a gaseous mixture comprising formaldehyde, dimethyl ether, dioxygen, diluent, carbon monoxide, carbon dioxide and water vapor; cooling the gaseous oxidation mixture with an adsorption liquid and adsorbing formaldehyde therein; and separating the resulting liquid source of formaldehyde from a mixture of gases comprising dioxygen, diluent, carbon monoxide, carbon dioxide and water vapor.
  • a source of formaldehyde is formed by subjecting dimethyl ether in the vapor phase to hydration and oxidation in the_ presence a catalytically effective amount of an oxidation promoting catalyst comprising tungsten oxide as an essential catalyst component at elevated temperatures to form a gaseous mixture comprising formaldehyde, dimethyl ether, dioxygen, diluent, carbon monoxide, carbon dioxide and water vapor; cooling the gaseous mixture to predominantly condense water and adsorb formaldehyde therein; and separating the resulting aqueous source of formaldehyde from a mixture of gases comprising dioxygen, diluent, carbon monoxide, carbon dioxide and water vapor.
  • the ratio of dioxygen to total dimethyl ether is, according to the present invention, any mole ratio which results in the production of the desired source of formaldehyde.
  • the ratio of dioxygen to ether and, if present, alkanol is preferably between about 1 : 1 and about 1 : 1000 moles. More preferably, the ratio of dioxygen to dimethyl ether is between about 1 : 1 and about 1 : 100 moles. Most preferably, the ratio of dioxygen to dimethyl ether is between about 1 : 1 and about 1 : 10 moles.
  • Air 99 mol percent to 82.6 mol percent Reaction temperature: 200° to 450°C
  • Dimethyl ether 3 mol percent to 12 mol percent Reaction temperature: 250° to 400°C.
  • the dioxygen can be added to the reaction mixture as pure molecular oxygen, or diluted with an inert gas such as nitrogen or argon. It is preferred to keep the dioxygen at no more than 10 mole percent of the entire reaction feed so as 4o avoid the formation of explosive mixtures.
  • dimethyl ether is oxidized with a source of dioxygen in the presence of an oxidation-promoting catalytic composition containing, as an essential ingredient, a metal oxide with or without up to about 10 percent of a supplemental inorganic compound based upon the total weight of metal oxide and supplemental inorganic compounds
  • Suitable metal oxide catalysts have been developed for reacting dimethyl ether with a source of dioxygen to produce formaldehyde, as described in U.S. Patent Number 3,655,771, or U.S. Patent Number 4,753,916.
  • Well known methods of preparing suitable tungsten oxide include adding to ammonium tungstate concentrated hydrochloric or nitric acid, to precipitate the oxide.
  • Oxide is molded into tablets or supported on inert carriers, such as alumina, Carborundum, pumice or the like.
  • vanadium oxide, boron oxide, molybdenum oxide, phosphoric acid, an ammonium salt thereof, ammonium chloride or the like is added to tungsten oxide in an amount of not more than 10%, in order to maintain the activity of tungsten oxide at the original level and to obtain a catalyst having a sufficient mechanical strength to withstand operating conditions during its useful catalytic life.
  • the addition thereof results in the combination with tungsten oxide and consequently the aggregatability of powdered tungsten oxide is enhanced, molding of the oxide is facilitated and the oxide is hardened.
  • tungsten oxide powder produced by any generally known method
  • the resulting mixture is milled well with water into a paste.
  • This paste is dried, ground into 12 mesh, size- controlled and shaped into tablets by a tablet-forming machine. These tablets are sufficiently dried, and thereafter calcined in air at 500°C for 7 to 8 hours to obtain very hard tablets.
  • the present invention further provides a method for selective oxidation of dimethyl ether to formaldehyde in the presence of an catalytically effective amount of a composition of matter comprising ⁇ - Mo(i - x )W x O3, where x is a number between 0 and 1, preferably where x is a number between 0 and 0.5, and more preferably where x is 0 or a number between 0 and 0.1.
  • a composition of matter comprising ⁇ - Mo(i - x )W x O3, where x is a number between 0 and 1, preferably where x is a number between 0 and 0.5, and more preferably where x is 0 or a number between 0 and 0.1.
  • the selective oxidation of dimethyl ether to formaldehyde is conducted at temperatures in a range from about 200° to about 450°C, and more preferably in a range from about 250° to about 400°C.
  • Preferred operating pressures are from about 1 to about
  • One method for preparation of a composition comprising ⁇ - M ⁇ ( i- ⁇ )W x O 3 , comprises spray-drying a solution of molybdic acid or molybdic and tungstic acids in appropriate concentrations and heating the resulting powder at a temperature of from about 275° to about 450° C.
  • Another method comprises sputtering a molybdenum or mixed metal oxide target in appropriate concentrations onto a thermally floating substrate in an atmosphere comprising oxygen and an inert gas wherein the oxygen is in an amount from about 5 to about 50 volume percent.
  • Most preferred compositions comprising ⁇ - M ⁇ (i- x )W x ⁇ 3 are where x is 0 or a number between 0 and 0.05.
  • This phase of the specified metal or mixed metal oxide has a distorted three dimensional RCO 3 structure based on corner-linked octahedra.
  • the thermal stability of the beta phase of M0O 3 can be improved by tungsten substitution as evidenced by the beta to alpha transformation temperature of about 530°C of Moo .95 Wxo .05 Q 3 , compared to about 450°C of Mo ⁇ 3.
  • compositions comprising the "beta" phase of the specified metal and mixed metal oxides ( ⁇ - M ⁇ (i- x )W x O3) can be prepared in films by sputtering or spin coating.
  • dimethyl ether may be used alone, or methanol and dimethyl ether can be used in admixture with each other to produce formaldehyde.
  • a mixture containing dimethyl ether in substantially liquid form is supplied from dimethyl ether storage vessel 12 to pump 1 4 through conduit 13 , and into feed manifold 92 through conduit 1 5.
  • a recycle stream of wet gas is transferred into feed manifold 92 through conduit 98 .
  • a gaseous stream containing dioxygen and dinitrogen from a source (not shown) is supplied to compressor 94 through conduit 93 .
  • Compressed gas is transferred through conduit 95 , combined in feed manifold 92 with the recycle stream of wet gas from the formaldehyde adsorber and the dimethyl ether.
  • the resulting feed mixture is heated against reactor effluent in heat exchanger 76 , and transferred into oxidation reactor 90 through conduit 91 .
  • Oxidation reactor 90 is a vertical heat exchanger.
  • the tubes are filled with catalyst pellets. (The upper and lower regions of the tubes contain pellets of inert material.)
  • a portion of heat generated in the catalyst bed is diverted to steam generation within oxidation reactor 90 thereby providing cooling of effluent from the bed (not shown).
  • a thermal fluid is vaporized on the shell side and circulated to a steam generator to generate steam at pressures of up to 300 psig.
  • an oxidation-promoting catalyst preferably consisting essentially of a metal oxide component with or without a supplemental inorganic compound.
  • tungsten oxide catalysts are used because they give almost complete oxidation to formaldehyde at much lower temperatures than are required for the silver-catalyzed dehydrogenation reaction.
  • Gaseous effluent from oxidation reactor 90 is transferred through conduit 96 , cooled against the reactor feedstream in exchanger 76 and then passed through conduit 97 into spray column 1 00 where a solution of aqueous formaldehyde in methanol is formed.
  • Formaldehyde solution from the bottom of spray column 1 00 at temperatures in a range downward from about 100°C to about 75°C, is supplied to pump 1 04 through conduit 103 .
  • Formaldehyde solution from the spray column is generally from about 30 to about 85 percent by weight formaldehyde in methanol solution containing less than about 5 percent water and less than 350 ppm of formic acid.
  • a portion of the stream can optionally be diverted from adsorption tower 100 for delivery to a destination (not shown) where the stream may subsequently be separated to recover, for example, formaldehyde and methanol and/or dimethyl ether.
  • the stream can alternatively be utilized as a source of feed stock for chemical manufacturing.
  • the formaldehyde solution from pump 1 04 is combined with a solution of formaldehyde in methanol supplied from the bottom of adsorption column 1 10 through conduits 1 13 and 108 , by means of pump 1 14.
  • the combination forms a stream which is circulated to the top of spray column 100 through conduit 106. It is important to maintain the temperature of the pump- around stream above about 70°C to prevent paraformaldehyde formation.
  • a portion of the cooling required in spray column 100 may be obtained by including a heat exchanger in the flow through conduit 1 06.
  • a gaseous overhead stream from spray column 100 is transferred through conduit 102 into adsorption column 1 1 0 , which contains a high efficiency packing or other means for contacting counter-currently the gaseous stream with aqueous adsorption liquid.
  • a solution of formaldehyde in methanol from the bottom of adsorption column 1 10 is circulated in a pump- around to a lower section of the column through conduits 1 13 and 1 1 5 , cooler 1 1 6 , and conduit 1 1 7 by means of rjump 1 14 .
  • methanol for the adsorption is supplied to a section of adsorption column 1 10 by means of pump 48 through conduit 125 , cooler 126 , and conduit 128 . Further up the column, pump-arounds may be cooled to successively lower temperatures. In some configurations, the lower pump- around stream is not cooled at all.
  • a vapor side draw from adsorption column 1 1 0 is transferred through conduit 1 12 and mixed with fresh air as previously described.
  • the adsorber overhead passes through conduit 1 1 8 into condenser 122 .
  • An appropriate amount of condensate is formed and refluxed to the top section of the adsorber column through conduit 124.
  • Overhead temperatures in adsorption column 1 1 0 are in a range of about 15° to about 55°C, preferably about 30° to about 40°C. Gases are vented from condenser 122 through conduit 120 to disposal, typically, in a thermal oxidation unit (not shown).
  • the absorber overhead which contains trace amounts of formaldehyde (about 10-30 ppm), is treated in several ways by catalytic or thermal converter to oxidize hydrocarbons and recuperative heat exchange. Typically, 170 psig to 200 psig steam is generated to improve overall economics of preferred embodiments of the invention.
  • a portion of the solution of formaldehyde in methanol is diverted from pump 1 04 into reactive distillation column 50 through conduit 45.
  • reactive distillation column 50 simultaneous chemical reaction and multicomponent distillation are carried out coextensively in the same high efficiency, continuous separation apparatus.
  • a stream containing methanol from storage vessel 46 may by fed into the reactive distillation column 50.
  • Charge pump 48 transfers methanol in substantially liquid form into the reactive distillation column 50 through conduits 47 and 49.
  • Solid acidic catalyst is present in the reactive distillation column 50 to allow solutions containing water, methanol, formaldehyde, methylal and one or more other polyoxymethylene dimethyl ethers to be brought into solid-liquid contact counter-currently with the catalyst to form products including methylal and higher molecular weight polyoxymethylene dimethyl ethers. More volatile reaction products are taken overhead from the high efficiency separation apparatus, whereas water and less volatile reaction products are carried down the high efficiency separation apparatus.
  • the overhead vapor stream from reactive distillation column 50 is transferred through conduit 52 into condenser 54.
  • a suitable portion of condensate from condenser 54 is refluxed into reactive distillation column 50 through conduits 55 and 56.
  • a product stream containing methylal is transferred through conduit 58 to product storage (not shown).
  • Conduit 59 supplies pump 60 with liquid containing higher molecular weight polyoxymethylene dimethyl ethers from the bottom of column 50.
  • a suitable portion of liquid from the bottom of column 50 is transferred, by means of pump 60 , through conduits 62 and 63 into reboiler 64 which is in flow communication with the bottom of the column by means of conduit 66.
  • a product stream containing higher molecular weight polyoxymethylene dimethyl ethers is transferred through conduit 68 to product storage (not shown).
  • product storage not shown.
  • an anion exchange resin is disposed within a section of the distillation column below the stages of contact with the acidic catalyst to form an essentially acid-free mixture.
  • An aqueous side stream containing low levels of unreacted formaldehyde and/or methanol is discharged from column 50 through conduit 72.
  • the side stream from column 50 is transferred by means of pump 74 through conduit 75 to waste disposal (not shown).
  • tungsten oxide catalyzes the conversion of dimethyl ether to formaldehyde by an oxidation reaction at temperatures in a range from about 350° to about 600°C , preferably in a range from about 400° to about
  • FIGURE 4 Still another preferred aspect of the invention is depicted schematically in FIGURE 4.
  • a feedstream comprising methanol, formaldehyde and a soluble condensation promoting component capable of activating a heterogeneous acidic catalyst is provided by contacting dimethyl ether in the vapor phase with a catalytically effective amount of an oxidative dehydrogenation promoting catalyst comprising silver as an essential catalyst component at elevated temperatures to form a gaseous mixture comprising formaldehyde, methanol, dioxygen, diluent gas, carbon dioxide and water vapor; cooling the gaseous dehydrogenation mixture with an adsorption liquid and adsorbing formaldehyde therein; and separating the resulting liquid source of formaldehyde from a mixture of gases comprising dioxygen, diluent, carbon monoxide, carbon dioxide and water vapor.
  • recycle gas from the formaldehyde absorber is combined with air, mixed with dimethyl ether,
  • dimethyl ether is oxidized with a source of dioxygen in the presence of an oxy-dehydrogenation catalytic composition containing, as an essential ingredient, .silver with or without up to about 10 percent of a supplemental inorganic compound based upon the total weight of metal oxide and supplemental inorganic compounds.
  • Suitable oxy- dehydrogenation catalysts have been developed for converting methanol with a source of dioxygen to produce formaldehyde, as described in U.S. Patent Number 5,401 ,884, U.S. Patent
  • the starting materials are fed through a silver-containing fixed-bed catalyst installed in a vertical tubular reactor.
  • the catalyst preferably comprises silver crystals having a particle size of from 0.1 to 3 mm, in particular from 0.2 to 2.5 mm.
  • the fixed- bed catalyst can have a multi-layer structure through arrangement of the silver crystals in layers of different particle size.
  • the starting mixture of dimethyl ehter vapor, oxygen- containing gas, and, if used, steam and inert gas is preferably passed through the tubular reactor from top to bottom.
  • the process is carried out in one step by passing the starting mixture through the fixed catalyst bed at from 550° to 750°C, in particular from 600° to 720°C, particularly advantageously at from 660° to 700°C.
  • the process is preferably carried out continuously at from 0.5 to 3 bar, in particular at from 0.8 to 2 bar, preferably at from 1 to 1.5 bar.
  • the residence times in the catalyst zone are from 0.001 to 1 second, preferably from 0.002 to 0.1 second.
  • the reaction gases leaving the catalyst zone are advantageously cooled within a short time, for example to below 350°C.
  • the cooled gas mixture can expediently be fed to an adsorption tower, in which the formaldehyde is washed out of the gas mixture by means of water.
  • dimethyl ether may be used alone, or methanol and dimethyl ether can be used in admixture with each other to produce formaldehyde.
  • a mixture containing dimethyl ether in substantially liquid form is supplied from dimethyl ether storage vessel 12 to pump 1 4 through conduit 13.
  • Dimethyl ether is transferred through conduit 1 6 into feed manifold 92 .
  • a recycle stream of wet gas is transferred into feed manifold 92 by means of blower 88.
  • a gaseous stream containing dioxygen and dinitrogen from a source (not shown) is supplied to compressor 94 through conduit 93 .
  • Compressed gas is transferred through conduit 95 , combined in feed manifold 92 with the recycle stream of wet gas from the formaldehyde adsorber and the dimethyl ether.
  • the resulting mixture is heated against reactor effluent in heat exchanger 80 , and transferred into oxidation reactor 90 through conduit 82 and feed manifold 84
  • Formaldehyde reactor 90 contains an oxidative dehydrogenation catalyst disposed in a thin layer directly above a vertical heat exchanger where effluent from the catalyst layer is promptly cooled.
  • Boiler feed water at about 110° to 130°C is supplied through conduit 85 to the heat exchanger for generation of low pressure steam in the lower section of the formaldehyde reactor.
  • the steam is transferred through conduit 86 , mixed with the preheated mixture of dimethyl ether, wet recycle gas and air stream in feed manifold 84 , and transferred into formaldehyde reactor 90. Steam is metered into the preheated methanol-air mixture to control the reactor outlet temperature.
  • the mole ratio of fresh air feed to methanol is between 0.5 and 2.0, preferably about 1.25 and typically the mole ratio of dimethyl ether to steam is about 3.
  • the pressure is only slightly above atmospheric. Since the catalyst layers are less than one inch in thickness, the pressure drop is negligible.
  • metallic silver catalyzes the conversion of dimethyl ether to formaldehyde by a reversible dehydrogenation reaction at temperatures from about 500° to 700°C:
  • the oxidative dehydrogenation catalyst is generally silver crystals supported on a stainless steel mesh, or a shallow bed of silver crystals, spherical particles, or granules.
  • the reaction is endothermic, and theoretical equilibrium is approximately 50 percent yield at 400°C, 90 percent at 500°C, and 99 percent at 700°C.
  • a portion of the hydrogen formed is oxidized to water. Formation of water is exothermic and provides heat to maintain the endothermic hydrogenation reaction. Heat is also provided by the direct oxidation of methanol:
  • Methanol conversion in the reactor is typically between 65 percent and 80 percent, depending largely on the amount of steam introduced at the methanol vaporization step.
  • Formaldehyde is lost by several side reactions, including those producing co-products including carbon monoxide, carbon dioxide, methane, formic acid, and methyl formate.
  • Gaseous effluent from oxidation reactor 90 is transferred through conduit 96 , cooled against the reactor feedstream in exchanger 80 and then passed to an absorption system, where aqueous formaldehyde is absorbed in methanol.
  • the effluent gases flow through conduit 98 into spray column 100 where a solution of formaldehyde is formed.
  • Formaldehyde solution from the bottom of spray column 1 00 at temperatures in a range downward from about 100°C to about 75°C, is supplied to pump 104 through conduit 103.
  • a portion of the aqueous formaldehyde is transferred through conduit 45 into reactive distillation column 50.
  • Formaldehyde solution from the spray column is generally about 55 percent by weight formaldehyde, about 43 methanol weight percent about 2 weight percent water and less than 350 ppm of formic acid.
  • a portion of the stream can optionally be diverted from adsorption tower 1 00 for delivery to a destination (not shown) where the stream may subsequently be separated to recover, for example, formaldehyde and methanol and/or dimethyl ether.
  • the stream can alternatively be utilized as a source of feed stock for chemical manufacturing.
  • Formaldehyde solution is combined with a solution of formaldehyde supplied from the bottom of adsorption column 1 10 through conduits 1 13 and 108 , by means of pump 1 14 , and circulated to the top of spray column 100 through conduit 1 06 . It is important to maintain the temperature of the pump-around stream above about 70°C to prevent paraformaldehyde formation.
  • a portion of the cooling required in spray column 1 00 may be obtained by including a heat exchanger in the flow through conduit 1 06 .
  • a gaseous overhead stream from spray column 1 00 is transferred through conduit 1 02 into adsorption column 1 10 , which contains a high efficiency packing or other means for contacting counter-currently the gaseous stream with aqueous adsorption liquid.
  • a dilute aqueous formaldehyde from the bottom of adsorption column 1 10 is circulated in a pump-around to the bottom section of the column through conduits 1 13 and 1 15 , cooler 1 16 , and conduit 1 17 by means of pump 1 14.
  • a liquid side stream is supplied to pump 124 through conduit 125 , transferred through manifold 127 , cooled in cooler 126 , and returned to adsorption column 1 10 through conduit 128 .
  • the lower pump-around stream is not cooled at all.
  • Caustic solution may be added to the chilled water to improve absorber performance, but it leaves traces of sodium as a contaminant in the product.
  • a vapor side draw from adsorption column 1 1 0 is transferred through conduit 1 1 2 and mixed with fresh air as previously described.
  • the adsorber overhead passes through conduit 1 1 8 into condenser 122 .
  • An appropriate amount of condensate is formed and refluxed to the top section of the adsorber column through conduit 123 .
  • Overhead temperatures in adsorption column 1 10 are in a range of about 15° to about 55°C, preferably about 30° to about 40°C. Gases are vented from condenser 122 through conduit 120 to disposal, typically, in a thermal oxidation unit (not shown).
  • the absorber overhead which contains trace amounts of formaldehyde (about 10-30 ppm), is treated in several ways by catalytic or thermal converter to oxidize hydrocarbons and recuperative heat exchange. Typically, 170 psig to 200 psig steam is generated to improve overall economics of preferred embodiments of the invention.
  • a portion of the solution of formaldehyde in methanol is diverted from pump 104 into reactive distillation column 50 through conduit 45.
  • reactive distillation column 50 simultaneous chemical reaction and multicomponent distillation are carried out coextensively in the same high efficiency, continuous separation apparatus.
  • a stream containing methanol from storage vessel 46 may by fed into the reactive distillation column 50.
  • Charge pump 48 transfers methanol in substantially liquid form into the reactive distillation column 50 through conduits 47 and 49.
  • Solid acidic catalyst is present in the reactive distillation column 50 to allow solutions containing water, methanol, formaldehyde, methylal and one or more other polyoxymethylene dimethyl ethers to be brought into solid-liquid contact counter-currently with the catalyst to form products including methylal and higher molecular weight polyoxymethylene dimethyl ethers. More volatile reaction products are taken overhead from the high efficiency separation apparatus, whereas water and less volatile reaction products are carried down the high efficiency separation apparatus.
  • the overhead vapor stream from reactive distillation column 50 is transferred through conduit 52 into condenser 54.
  • a suitable portion of condensate from condenser 54 is refluxed into reactive distillation column 50 through conduit 56.
  • a product stream containing methylal is transferred through conduit 58 to product storage (not shown).
  • Conduit 59 supplies pump 60 with liquid containing higher molecular weight polyoxymethylene dimethyl ethers from the bottom of column 50.
  • a suitable portion of liquid from the bottom of column 50 is transferred, by means of pump 60 , through conduits 62 and 63 into reboiler 64 which is in flow communication with the bottom of the column by means of conduit 66.
  • a product stream containing higher molecular weight polyoxymethylene dimethyl ethers is transferred through conduit 68 to product storage (not shown).
  • an anion exchange resin is disposed within a section of the distillation column below the stages of contact with the acidic catalyst to form an essentially acid-free mixture.
  • An aqueous side stream containing low levels of unreacted formaldehyde and/or methanol is discharged from column 50 through conduit 72.
  • a catalyst of copper, zinc and selenium was used at several elevated temperatures to convert a liquid feedstream of aqueous methanol and a gaseous feedstream of dimethyl ether, nitrogen and dihydrogen.
  • Effluent of the fixed bed reactor was a gaseous dehydrogenation mixture including formaldehyde, dimethyl ether, dihydrogen and carbon monoxide.
  • a tubular quartz reactor was charged with 9.27 grams (5 cc) of the CuZnSe particles which had been sieved to 18-40 mesh.
  • the tubular quartz reactor (approx. 10 mm inside diameter) was equipped with a quartz thermowell terminating at about the midpoint of the catalyst bed.
  • a liquid feed solution was prepared using 13.06 grams of water and 17.33 grams of methanol. The resulting solution was fed by a syringe pump into a preheat zone above the catalyst bed. Using mass flow controllers, a gaseous feedstream of 26.9 percent by volume dimethyl ether, 6.62 volume percent nitrogen and a balance of dihydrogen was also fed to the top of the reactor.
  • Liquid products from the reactor were collected in a cool
  • a silver catalyst in the form of needles was used at several elevated temperatures to provide a source of formaldehyde by oxidative dehydrogenation of dimethyl ether, steam and methanol.
  • a tubular quartz reactor was charged with 3.83 grams (1 cc) of the silver needles.
  • the tubular quartz reactor (approx. 10 mm inside diameter) was equipped with a quartz thermowell terminating at about the midpoint of the catalyst bed. Quartz wool was placed above the catalyst zone to assist in vaporizing liquid feed.
  • the liquid feed solution containing 18.6 percent methanol and 81.4 percent by weight water was fed by a syringe pump into the preheat zone above the catalyst bed.
  • a silver catalyst in the form of needles was used at several elevated temperatures to provide a source of formaldehyde by nonoxidative dehydrogenation of dimethyl ether and steam.
  • the liquid feed of water was fed by a syringe pump into the preheat zone above the catalyst bed.
  • a gaseous feedstream of 89.1 percent by volume dimethyl ether and 10.9 volume percent nitrogen was also fed to the top of the reactor.
  • Samples were collected while temperature of the catalyst bed was controlled to temperatures in a range from about 400° to about 650°C. Operating conditions and results are summarized in Table V.
  • substantially is defined as occurring with sufficient frequency or being present in such proportions as to measurably affect macroscopic properties of an associated compound or system. Where the frequency or proportion for such impact is not clear, substantially is to be regarded as about twenty per cent or more.
  • the term “essentially” is defined as absolutely except that small variations which have no more than a negligible effect on macroscopic qualities and final outcome are permitted, typically up to about one percent.
  • HPE is higher polyoxymethylene dimethyl ethers which are CH3 ⁇ (CH2 ⁇ )nCH3 having n greater than 1
  • MeO is methoxy moiety
  • DME is dimethyl ether.
  • HPE is higher polyoxymethylene dimethyl ethers which are CH 3 ⁇ (CH 2 ⁇ )nCH3 having n greater than 1
  • MeO is methoxy moiety
  • DME is dimethyl ether.
  • HPE is higher polyoxymethylene dimethyl ethers which are CH3 ⁇ (CH2 ⁇ )nCH3 having n greater than 1
  • MeO is methoxy moiety
  • DME is dimethyl ether.
  • HPE is higher polyoxymethylene dimethyl ethers which are CH3 ⁇ (CH2 ⁇ )nCH3 having n greater than 1
  • MeO is methoxy moiety
  • DME is dimethyl ether.
  • HPE is higher polyoxymethylene dimethyl ethers which are CH 3 ⁇ (CH 2 ⁇ )nCH3 having n greater than 1
  • MeO is methoxy moiety
  • DME is dimethyl ether.
  • HPE is higher polyoxymethylene dimethyl ethers which are CH3 ⁇ (CH2 ⁇ )nCH3 having n greater than 1
  • MeO is methoxy moiety
  • DME is dimethyl ether.

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Abstract

L'invention concerne un procédé particulier qui consiste à apporter un flux d'entrée comprenant du méthanol, un promoteur de condensation soluble capable d'activer un catalyseur hétérogène acide et une source de formaldéhyde; et à chauffer ce flux d'entrée avec le catalyseur acide hétérogène dans une colonne de distillation catalytique de manière à transformer le méthanol et le formaldéhyde présents en méthylal et en polyoxyméthylène diméthyléthers supérieurs, puis à séparer le méthylal des polyoxyméthylène diméthyléthers supérieurs. Le méthylal et les polyoxyméthylène diméthyléthers supérieurs sont formés et séparés dans une colonne de distillation catalytique. L'ajout au sein de la colonne d'une section contenant une résine d'échange d'anions permet d'obtenir un produit essentiellement exempt d'acide pouvant être directement utilisé comme composé de mélange ou fractionné, en vue d'une distillation ultérieure, de manière à obtenir des composés se prêtant mieux à une transformation en carburant diesel.
PCT/US1999/020751 1998-11-12 1999-09-09 Preparation de polyoxymethylene dimethylethers par la conversion catalytique activee par acide de methanol avec du formaldehyde WO2000029365A2 (fr)

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US19031398A 1998-11-12 1998-11-12
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US09/190,313 1998-11-12
US09/190,699 US6265528B1 (en) 1998-11-12 1998-11-12 Preparation of polyoxymethylene dimethyl ethers by acid-activated catalytic conversion of methanol with formaldehyde formed by oxy-dehydrogenation of dimethyl ether
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WO2006045506A1 (fr) * 2004-10-25 2006-05-04 Basf Aktiengesellschaft Procédé pour produire des polyoxyméthylène diméthyléthers
WO2007051658A1 (fr) * 2005-06-15 2007-05-10 Basf Aktiengesellschaft Procede de fabrication d’ethers dimethyliques de polyoxymethylene a partir de methanol et de formaldehyde
CN102372611A (zh) * 2010-08-23 2012-03-14 中国石油化工股份有限公司 制备聚甲醛二甲醚的方法
CN102372615A (zh) * 2010-08-23 2012-03-14 中国石油化工股份有限公司 催化蒸馏制备聚甲醛二甲醚的方法
CN102372613A (zh) * 2010-08-23 2012-03-14 中国石油化工股份有限公司 生产聚甲醛二甲醚的方法
CN102432441A (zh) * 2011-09-30 2012-05-02 天津大学 一种聚甲氧基甲缩醛的合成方法
CN104086380A (zh) * 2014-07-07 2014-10-08 中国科学院山西煤炭化学研究所 聚甲氧基二甲醚的制备方法
CN104177237A (zh) * 2014-08-15 2014-12-03 华东师范大学 一种聚甲醛二甲醚的合成方法
CN104292084A (zh) * 2014-09-05 2015-01-21 中国科学院山西煤炭化学研究所 高硅铝比分子筛催化制备聚甲醛二甲醚的方法
CN105294411A (zh) * 2014-07-24 2016-02-03 中国石油化工股份有限公司 由多聚甲醛生产聚甲醛二甲基醚的方法
EP3323800A1 (fr) * 2016-11-17 2018-05-23 OME Technologies GmbH Procédé de fabrication des éthers diméthyliques de polyoxyméthylène à partir du formaldéhyde et du méthanol dans des solutions aqueuses

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WO2006045506A1 (fr) * 2004-10-25 2006-05-04 Basf Aktiengesellschaft Procédé pour produire des polyoxyméthylène diméthyléthers
WO2007051658A1 (fr) * 2005-06-15 2007-05-10 Basf Aktiengesellschaft Procede de fabrication d’ethers dimethyliques de polyoxymethylene a partir de methanol et de formaldehyde
JP2008546665A (ja) * 2005-06-15 2008-12-25 ビーエーエスエフ ソシエタス・ヨーロピア ポリオキシメチレンジメチルエーテルをメタノールおよびホルムアルデヒドから製造する方法
US7700809B2 (en) 2005-06-15 2010-04-20 Basf Aktiengesellschaft Process for preparing polyoxymethylene dimethyl ethers from methanol and formaldehyde
AU2006310719B2 (en) * 2005-06-15 2011-03-31 Basf Aktiengesellschaft Process for preparing polyoxymethylene dimethyl ethers from methanol and formaldehyde
CN102372615B (zh) * 2010-08-23 2014-03-05 中国石油化工股份有限公司 催化蒸馏制备聚甲醛二甲醚的方法
CN102372615A (zh) * 2010-08-23 2012-03-14 中国石油化工股份有限公司 催化蒸馏制备聚甲醛二甲醚的方法
CN102372613A (zh) * 2010-08-23 2012-03-14 中国石油化工股份有限公司 生产聚甲醛二甲醚的方法
CN102372611B (zh) * 2010-08-23 2014-01-22 中国石油化工股份有限公司 制备聚甲醛二甲醚的方法
CN102372611A (zh) * 2010-08-23 2012-03-14 中国石油化工股份有限公司 制备聚甲醛二甲醚的方法
CN102372613B (zh) * 2010-08-23 2014-03-05 中国石油化工股份有限公司 生产聚甲醛二甲醚的方法
CN102432441A (zh) * 2011-09-30 2012-05-02 天津大学 一种聚甲氧基甲缩醛的合成方法
CN104086380A (zh) * 2014-07-07 2014-10-08 中国科学院山西煤炭化学研究所 聚甲氧基二甲醚的制备方法
CN105294411A (zh) * 2014-07-24 2016-02-03 中国石油化工股份有限公司 由多聚甲醛生产聚甲醛二甲基醚的方法
CN105294411B (zh) * 2014-07-24 2017-06-20 中国石油化工股份有限公司 由多聚甲醛生产聚甲醛二甲基醚的方法
CN104177237A (zh) * 2014-08-15 2014-12-03 华东师范大学 一种聚甲醛二甲醚的合成方法
CN104177237B (zh) * 2014-08-15 2015-11-18 华东师范大学 一种聚甲醛二甲醚的合成方法
CN104292084A (zh) * 2014-09-05 2015-01-21 中国科学院山西煤炭化学研究所 高硅铝比分子筛催化制备聚甲醛二甲醚的方法
CN104292084B (zh) * 2014-09-05 2016-01-27 中国科学院山西煤炭化学研究所 高硅铝比分子筛催化制备聚甲醛二甲醚的方法
EP3323800A1 (fr) * 2016-11-17 2018-05-23 OME Technologies GmbH Procédé de fabrication des éthers diméthyliques de polyoxyméthylène à partir du formaldéhyde et du méthanol dans des solutions aqueuses

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