WO1997011928A1 - Procede de conversion du gaz naturel produisant du methanol - Google Patents

Procede de conversion du gaz naturel produisant du methanol Download PDF

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Publication number
WO1997011928A1
WO1997011928A1 PCT/US1996/015234 US9615234W WO9711928A1 WO 1997011928 A1 WO1997011928 A1 WO 1997011928A1 US 9615234 W US9615234 W US 9615234W WO 9711928 A1 WO9711928 A1 WO 9711928A1
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WO
WIPO (PCT)
Prior art keywords
reactor
natural gas
thermal
chloride
hydrogen chloride
Prior art date
Application number
PCT/US1996/015234
Other languages
English (en)
Inventor
John E. Stauffer
Original Assignee
Stauffer John E
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Stauffer John E filed Critical Stauffer John E
Priority to AU71648/96A priority Critical patent/AU7164896A/en
Publication of WO1997011928A1 publication Critical patent/WO1997011928A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/48—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by oxidation reactions with formation of hydroxy groups
    • C07C29/50—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by oxidation reactions with formation of hydroxy groups with molecular oxygen only
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/013—Preparation of halogenated hydrocarbons by addition of halogens
    • C07C17/04—Preparation of halogenated hydrocarbons by addition of halogens to unsaturated halogenated hydrocarbons
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/09—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis
    • C07C29/12—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of esters of mineral acids
    • C07C29/124—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of esters of mineral acids of halides

Definitions

  • the present invention relates to an improvement in processes designed to produce methyl alcohol from natural gas using chlorination technology.
  • the improvement permits the use of natural gas containing significant levels of inert gases while achieving high methane efficiencies.
  • the process encompasses the use of multiple thermal chlorination reactors, each with a natural gas recycle loop. These thermal reactors are arranged in multiple combination whereby the gas purge from the first thermal reactor is fed to the second thermal reactor, and so on until the last thermal reactor, which is vented to the atmosphere.
  • natural gas from one source was reported to contain 96 percent methane by volume, 3.2 percent nitrogen and 0.8 percent carbon dioxide.
  • Another source contained 80.5 percent methane, 18.2 percent ethane and 1.3 percent nitrogen.
  • natural gas may contain anywhere from 0.1 percent to over 7 percent inerts.
  • inerts Although hydrocarbons other than methane can quite easily be extracted from natural gas, inerts present a more difficult challenge. Such inerts include nitrogen and carbon dioxide. In contrast to conventional processes for producing methanol via synthesis gas, technology based on chlorination chemistry cannot handle carbon dioxide. This gas, therefore, must be treated in the same manner as other inerts, notably nitrogen.
  • a further object is to be able to handle a wide variety of natural gas feedstocks while achieving high yields of product .
  • Still another object is to provide for a practical process by reducing investment and operating costs to a minimum.
  • methyl chloride is hydrolyzed with water over a catalyst to give methyl alcohol and hydrogen chloride .
  • perchloroethylene is oxychlorinated with hydrogen chloride and oxygen to produce hexachloroethane and water.
  • Methyl chloride which is required for the catalytic reaction, is produced by chlorinating natural gas with hexachloroethane in a thermal chlorination reactor.
  • the methane content of the natural gas is chlorinated to methyl chloride and lesser quantities of methylene chloride, chloroform and carbon tetrachloride.
  • hydrogen chloride and perchloroethylene are produced in the chlorination reactions.
  • an excess of natural gas is fed to the thermal reactor. This excess natural gas leaves the thermal reactor with the reaction products. To avoid its loss, the excess natural gas is recycled to the thermal reactor after first separating the reaction products including hydrogen chloride, methyl chloride and perchloroethylene.
  • the exit gas stream from each thermal reactor is first cooled to condense the perchloroethylene along with most of the methyl chloride as a liquid condensate. Uncondensed gases of the exit gas comprising methane, hydrogen chloride and inerts are sent to a first absorber where the hydrogen chloride and any additional methyl chloride is removed by scrubbing the gases with methyl alcohol thus providing spent methyl alcohol . The gas stream now free of hydrogen chloride and any methyl chloride, is passed to a second absorber in which methyl alcohol vapor is removed by scrubbing with the condensed perchloroethylene thus providing spent concentrate solution. The scrubbed gas comprising mostly methane and inerts is recycled to the thermal reactor.
  • Scrubbing solutions from both first and second absorbers are fed to the catalytic reactor.
  • inerts in the natural gas are not separated.
  • the levels of these gases, including nitrogen and carbon dioxide quickly build up in the recycle stream.
  • a purge stream must be taken from the thermal reactor through the gas recycle loop.
  • the purge stream could be vented to the atmosphere, but such a procedure would lead to significant losses of methane.
  • the present invention provides for the recovery of this methane by feeding the purge stream to a second thermal chlorination reactor.
  • the configuration of this second thermal reactor is very much like the first thermal reactor, comprising a natural gas recycle loop and a purge stream of its own. This second purge stream may be vented or fed to yet another thermal chlorination reactor.
  • thermal chlorination reactors used will depend on such factors as the concentration of inerts in the natural gas feed, the price of the natural gas, investment costs, and operating efficiencies.
  • the reactors will be connected in multiple combination such that natural gas is fed to the first thermal reactor, the purge from the first reactor is fed to the second reactor, the purge from the second reactor is fed to the third reactor (not shown) , and so on until the last thermal reactor, which is vented to the atmosphere.
  • the last thermal reactor which is vented to the atmosphere.
  • it is fed to the catalytic reactor to recover traces of methyl chloride and other organics.
  • the quantity of unreacted methane which is ultimately vented can be reduced to any desirable level .
  • Fig. 1 is a flow sheet of the process showing the catalytic reactor, first and second thermal chlorination reactors arranged in multiple combination, recycle loops for both thermal reactors, and lines connecting these units to provide a unified process.
  • the process of the present invention for the production of methyl alcohol from natural gas comprises the following steps: reacting methyl chloride, hydrogen chloride, oxygen and perchloroethylene in a catalytic reactor to give reaction products comprising methyl alcohol and hexachloroethane, separating the methyl alcohol from the hexachloroethane, reacting the isolated hexachloroethane with natural gas in a multiple combination of thermal chlorination reactors comprising at least first and second thermal chlorination reactors, which said second thermal chlorination reactor may be the last reactor in said combination, to produce methyl chloride, hydrogen chloride, perchloroethylene and unreacted natural gas, said thermal reactors being arranged such that the natural gas is fed to the first reactor, and further such that a purge
  • Both aforementioned hydrolysis and oxychlorination reactions are carried out in a catalytic reactor of shell and tube design.
  • the catalyst comprising optionally of salts of copper, zinc, potassium and other metals found to be efficacious, is deposited in the tubes of said reactor.
  • a fairly wide temperature range has been reported for the reactions in question, but generally temperatures between 200° and 375° C. are preferred.
  • the overall reaction which takes place is the reaction of methyl chloride, hydrogen chloride, oxygen and perchloroethylene to form methyl alcohol and hexachloroethane.
  • the oxygen may be supplied by air feed to the catalytic reactor.
  • the effluent stream from the catalytic reactor is cooled to condense the liquids. Noncondensed gases are vented.
  • the liquid condensate is fractionated in a distillation column to separate the methyl alcohol product from the hexachloroethane. Since hexachloroethane is a solid which sublimes at close to 186° C, it may be dissolved in an excess of perchloroethylene in order to transport it to the thermal reactors.
  • hexachloroethane is reacted with natural gas to convert methane to methyl chloride.
  • Hydrogen chloride and perchloroethylene are also formed in this reaction.
  • the reaction is carried out in the range of 400° to 700° C.
  • the reactor design consists of a single tube in which a static mixer may be inserted to promote plug flow. 11928 PC17US96/15234
  • the exit gases from the first thermal reactor are cooled to condense the liquids including a substantial fraction of the methyl chloride which is dissolved in the perchloroethylene.
  • Uncondensed gases comprising methane, hydrogen chloride and inerts are sent to a first absorber in which methanol is used to remove the hydrogen chloride.
  • the scrubbed methane is sent to a second absorber where the condensate from the first thermal reactor is used to remove methanol vapors from the natural gas stream.
  • the methane stream, now free of hydrogen chloride and any methanol, is recycled back to the first thermal reactor.
  • the liquid streams from both absorbers are fed to the catalytic reactor.
  • methyl alcohol is an excellent solvent for hydrogen chloride.
  • 47.0 gms. of hydrogen chloride are absorbed in 100 gms. of saturated solution of methyl alcohol.
  • Methyl chloride is also soluble in methyl alcohol.
  • the condensate from the thermal reactor effluent comprises mostly perchloroethylene, which is an excellent solvent for methyl alcohol.
  • a purge stream is taken from the natural gas recycle loop in order to remove inerts.
  • This purge stream is fed to a second thermal reactor which is very much like the first. As shown in Fig. 1 the purge from the second thermal reactor is fed to the catalytic reactor to recover traces of chlorinated hydrocarbons. The inerts are ultimately vented to the atmosphere along with the nitrogen from the air supply fed to the catalytic reactor.
  • thermal reactors The construction of the thermal reactors is quite simple and relatively inexpensive. Because thermal chlorination involves a chain reaction, it is fast, and the reactors are modest in size. The second reactor is considerably smaller than the first and if a third one is required, it would be even smaller. The considerations of size also apply to the absorbers used in the recycle loops. If, for example, the second reactor is one fifth the size of the first, then the absorbers for the second recycle loop can be scaled accordingly. Helping to reduce dimensions even further, the entire process including the catalytic reactor can be operated at elevated pressures. A range from 1 to 10 bar is recommended.
  • the design of the present invention is based on established principles of chemical engineering.
  • the design avoids the use of catalysts in the chlorination of natural gas for the purpose of improving the yield of methyl chloride. It achieves the same results by controlling the concentrations of reactants and products in the reaction. By not relying exclusively on the use of catalysts, the reliability and economics of the process are enhanced.
  • a key feature of the process is its flexibility.
  • a wide range of natural gas sources can be considered.
  • Lower grades of natural gas containing higher levels of inerts can be handled efficiently.
  • the present invention can make a significant contribution to the technology of producing methyl alcohol . With the increasing worldwide demand for methyl alcohol, the utility of the present invention is assured.
  • Example 1 Engineering calculations were made to determine the operating variables for an installation comprising two thermal chlorination reactors in series. The following parameters were assumed: the natural gas feed contained 7 percent inerts on a volume basis, total methane conversion in each reactor was taken as 80 percent, and the yield of methyl chloride from methane was assumed to be 98 percent. The results showed that the recycle ratio, equal to the ratio of the recycle stream to the gas feed, for the first thermal reactor was 6.25. The recycle ratio for the second thermal reactor was 5.36. The overall methane efficiency for this layout was 94.1 percent. Losses consisted of unreacted methane that was vented and higher chlorinated methane compounds such as methylene chloride .
  • a third thermal reactor was added to the arrangement described in example 1. This additional reactor took the purge stream from the second thermal reactor. The same conditions as assumed in example 1 were used. Thus, the total methane conversion in the third reactor was taken as 80 percent and the yield of methyl chloride was 98 percent. The results indicated a recycle ratio for the third thermal reactor equal to 2.78. The overall methane efficiency was increased to 97.2 percent.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention décrit un procédé de production d'alcool méthylique à partir du gaz naturel faisant appel aux techniques de chloration. Selon ce procédé, chlorure de méthyle, chlorure d'hydrogène, oxygène et tétrachloréthylène sont mis à réagir dans un réacteur catalytique pour produire du méthanol et de l'hexachloroéthane et on utilise le C2Cl6 pour chlorer le méthane d'une charge d'alimentation en gaz naturel dans plusieurs réacteurs thermiques de chloration, chacun doté d'une boucle de recyclage de gaz naturel. Ces réacteurs sont disposés en combinaison de sorte qu'une purge de gaz du premier réacteur thermique est envoyée dans le deuxième réacteur thermique, et ainsi de suite, si nécessaire, jusqu'à un dernier réacteur thermique qui est dégazé dans l'atmosphère.
PCT/US1996/015234 1995-09-25 1996-09-24 Procede de conversion du gaz naturel produisant du methanol WO1997011928A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU71648/96A AU7164896A (en) 1995-09-25 1996-09-24 Methanol process for natural gas conversion

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US53312495A 1995-09-25 1995-09-25
US08/533,124 1995-09-25

Publications (1)

Publication Number Publication Date
WO1997011928A1 true WO1997011928A1 (fr) 1997-04-03

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1996/015234 WO1997011928A1 (fr) 1995-09-25 1996-09-24 Procede de conversion du gaz naturel produisant du methanol

Country Status (2)

Country Link
AU (1) AU7164896A (fr)
WO (1) WO1997011928A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001007385A1 (fr) * 1999-07-27 2001-02-01 Stauffer John E Procede de conversion du gaz naturel produisant du methanol
US7812201B2 (en) 2008-10-01 2010-10-12 Targa Resources, Inc. Process and catalyst for converting alkanes

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5185479A (en) * 1992-04-21 1993-02-09 Stauffer John E Process for methyl alcohol

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5185479A (en) * 1992-04-21 1993-02-09 Stauffer John E Process for methyl alcohol

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001007385A1 (fr) * 1999-07-27 2001-02-01 Stauffer John E Procede de conversion du gaz naturel produisant du methanol
US7812201B2 (en) 2008-10-01 2010-10-12 Targa Resources, Inc. Process and catalyst for converting alkanes
US7968755B2 (en) 2008-10-01 2011-06-28 Sajet Development Llc Process and catalyst for converting alkanes

Also Published As

Publication number Publication date
AU7164896A (en) 1997-04-17

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