Classifications

• • 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
  • C10L3/00—Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas
  • C10L3/003—Additives for gaseous fuels
  • C10L3/006—Additives for gaseous fuels detectable by the senses

Definitions

• the present invention relates to low-sulfur odorants comprising or consisting of A) acrylic acid methyl ester and/or acrylic acid ethyl ester, B) tetrahydrothiophene (THT) and C) hydroquinone monomethyl ether in specific concentrations.
• the content of hydroquinone monomethyl ether is in this case very low.
• an odorant according to the invention can also comprise one, two or more components having a stabilizing effect, cf. in this regard the information given concerning components D) and E) below.
• the invention relates also to a corresponding fuel gas (preferably natural gas) having a methane content of at least 60% by weight, which comprises a content of the odorant according to the invention.
• the town and coke-oven gases used previously for the public supply of gas contained components having an intensive smell and therefore had a strong inherent smell, so that issuing gas could easily be perceived.
• gas odorizing refers to the addition of substances (odorants) which have an intensive smell and act as warning or alarm substances to gases having no significant inherent smell, i.e. to otherwise substantially or completely odorless gases.
• Natural gas consists mainly of methane (typical methane contents lie in the range of from 50 to 99% by weight, usually in the range of from 60 to 99% by weight and conventionally 80 to 99% by weight) and can, depending on their origin, additionally contain differing contents of ethane, propane and hydrocarbons of relatively high molecular weight.
• shock odorizing it can be beneficial to add to the gas a relatively large amount of odorant over a relatively long period of time.
• shock odorizing one to three times the amount of odorant is supplied to the gas, compared to conventional odorizing. Shock odorizing is applied for example during the putting-into-operation of new networks or line portions in order more rapidly to attain the minimum odorant concentration or else to identify small leaks in the gas installation.
• THT alone is ideal for reliable odorizing of gas.
• sulfur oxides are formed as combustion products to a greater degree when gases odorized in this way are burned.
• JP-B-51-007481 mentions that acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate and butyl acrylate are known to have weak odorizing properties for fuel gases and to be almost insignificant in this regard.
• the document describes and claims allyl acrylate as an effective odorizing component.
• JP-A 55-104393 describes that odorants containing an alkyne and at least 2 compounds selected from a group consisting of methyl acrylate, ethyl acrylate, methyl methacrylate, allyl methacrylate, ethyl propionate, methyl-n-butyrate, methyl isobutyrate and prenyl acrylate, and also if appropriate tert-butyl mercaptan, are suitable for odorizing fuel gases.
• the amount of odorant is, based on weight, 50 ppm (mg/kg of gas), preferably greater than or equal to 100 ppm.
• JP-B-51-034841 determined “odor threshold values” of various substances, wherein n-valeric acid, n-butyric acid, isobutyraldehyde and various methyl amines had low olfactory “odor threshold values”.
• Ethyl acrylate or n-valeric acid used alone did not have a sufficiently odorizing effect.
• An optimized mixture comprised 50-90% by weight of ethyl acrylate, 10-50% by weight of n-valeric acid and optionally triethyl amine.
• the mixture which was taken to be most effective comprised ethyl acrylate, n-valeric acid and triethyl amine, wherein this mixture contained equal parts by weight of n-valeric acid and triethyl amine and also 30 to 80% by weight of ethyl acrylate; a corresponding mixture consisting of 60% by weight of ethyl acrylate and 20% by weight of each of n-valeric acid and triethyl amine was added to a gaseous fuel gas at 10 mg/m 3 .
• Odorants for fuel gases consisting of ethyl acrylate (70% by weight) and tert-butyl mercaptan (30% by weight) are known from JP-B 51-021402. This mixture was added to a gaseous fuel gas in an amount of 5 mg/m 3 .
• Odorous substances for odorizing heating gases consisting of a) 30-70% by weight of C 1 -C 4 alkyl mercaptans, b) 10-30% by weight of n-valeraldehyde and/or isovaleraldehyde, n-butyric acid and/or isobutyric acid and also if appropriate c) up to 60% by weight of tetrahydrothiophene (THT) are described in DE-A 31 51 215. These odorants were added to heating gas in amounts of from 5-40 mg/m 3 .
• Mixtures containing a) 1 proportion by weight of dimethyl sulfide, b) 0.8-3 proportions by weight of tert-butyl mercaptan and c) 0.1-0.2 proportions by weight of tert-heptyl mercaptan or 0.05-0.3 proportions by weight of tert-hexyl mercaptan for odorizing fuel gases are known from JP-A 61-223094. These mixtures had a smell of tert-butyl mercaptan which is associated with the smell of the town gas.
• norbornene derivatives for fuel gas odorizing is known from JP-A55056190.
• LPG was mixed at 40 mg/kg with a mixture of equal parts of 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene or at 50 mg/kg with a mixture of 80% by weight of 5-ethylidene-2-norbornene and 20% by weight of ethyl acrylate.
• U.S. Pat. No. 4,487,613 proposes odorants for fuel gases having a high content of sulfur-containing compounds, which additionally contain the warning smell-strengthening compounds 2-methoxy-3-isobutyl pyrazine and/or 4-methyl-4-mercapto-2-pentanone.
• the odorants disclosed in accordance with U.S. Pat. No. 4,487,613 can also contain low contents of acrylic acid methyl ester.
• WO 2005/061680 describes the use of a mixture containing (a) at least two different acrylic acid C 1 -C 6 alkyl esters, (b) at least one compound from the group of the C 1 -C 8 mercaptans, the C 4 -C 12 thiophenes, the C 2 -C 8 sulfides or the C 2 -C 8 disulfides and (c) at least one compound from the group of the norbornenes, the C 1 -C 6 carboxylic acids, the C 1 -C 8 aldehydes, the C 6 -C 14 phenols, the C 7 -C 14 anisoles or the C 4 -C 14 pyrazines and also if appropriate (d) an antioxidant for odorizing fuel gas having a methane content of at least 60% by weight.
• WO 2005/103210 relates to odorants and accordingly odorized gases comprising
• WO 2005/103210 states in this regard inter alia that the nitroxides proposed therein effectively prevent the radical polarization, which is of course to be avoided in the case of odorants, of the acrylic acid esters contained therein.
• WO 2005/103210 regards mixtures comprising ethyl acrylate and THT as being particularly preferred.
• nitroxides proposed in accordance with WO 2005/103210 alone do not cause completely sufficient stabilization of the odorant in question.
• interactions can occur between the nitroxides and the thioethers, in particular in the presence of metals and metal surfaces, such as for example in the vessels for storing the odorants, so that the warning smell of the odorants proposed therein can change and become impaired.
• consumption can also occur as a result of abreaction of the nitroxides, so that comprehensive stabilization of the acrylic acid esters is no longer ensured in each case.
• nitroxides can be oxidized in the presence of copper ions (to form the corresponding nitrons) or reduced in the presence of iron ions (to form the corresponding N-hydroxy compounds).
• the subject-matter of the present invention is a mixture (referred to hereinafter as an “odorant”) comprising or (substantially) consisting of the following components:
• R is selected from the group consisting of H, —OH, —NH 2 , —O 2 CR 1 and —NOCR 1 , wherein R 1 represents an alkyl radical containing 1 to 4 carbon atoms, based on the total weight of the odorant.
• a corresponding method for odorizing fuel gases having a methane content of at least 60% by weight (of preferably natural gas) using an odorant according to the invention is also relevant in practice.
• an odorant according to the invention is added to the fuel gas.
• a further subject-matter of the present invention is a fuel gas having a methane content of at least 60% by weight comprising an odorant according to the invention.
• an odorant according to the invention With regard to the preferred odorants for use in fuel gases according to the invention, reference is made to the subsequent discussion of preferred odorants.
• the fuel gas to be odorized or the fuel gas according to the invention has a methane content of at least 60% by weight, preferably of at least 70% by weight and particularly preferably of at least 75% by weight.
• the total amount of acrylic acid methyl ester and acrylic acid ethyl ester (component (A)) in the odorants according to the invention is at least 75% by weight, preferably at least 84% by weight.
• the odorants according to the invention comprise acrylic acid methyl ester and acrylic acid ethyl ester
• the preferred ratio by weight of acrylic acid methyl ester to acrylic acid ethyl ester lies in the range of from 9:1-1:9, preferably in the range of from 7:3-3:7, in particular in the range of from 3:1-1:4.
• the ratio by weight of acrylic acid methyl ester to acrylic acid ethyl ester lies in the range of from 1:1-1:3.
• the compound tetrahydrothiophene (component (B)) is contained in the odorants according to the invention at 2-19.5% by weight, preferably at 5-15% by weight.
• component (C) The compound hydroquinone monomethyl ether (4-methoxyphenol, MeHQ) (component (C)) is contained in the odorants according to the invention in very low amounts lying in the range of from 5-50 ppm, preferably 10-20 ppm.
• component (C) is surprisingly not required to attain high stability of the odorant; the use of the low amount provided in accordance with the invention of component (C) is advantageous for stability reasons, in particular if component (E) is present (cf. also the examples).
• Odorants according to the invention preferably comprise
• component (D) 0.025-0.2% by weight of butylhydroxy toluene and/or butyl hydroxyanisole and/or as component (E) 5-500 ppm of one or more compounds of formula (I)
• R is selected from the group consisting of H, —OH, —NH 2 , —O 2 CR 1 and —NOCR 1 , wherein R 1 represents an alkyl radical containing 1 to 4 carbon atoms.
• the total amount of the compounds of component (D) butylhydroxy toluene (BHT, ionol, 2,6-di-tert-butyl-p-cresol, E 321) and/or butyl hydroxyanisole (BHA, E 320) in the odorants according to the invention lies in the range of from 0.025-0.2% by weight, preferably in the range of from 0.05-0.15% by weight.
• component (C) Owing to the presence of component (C), in particular in combination with one or both further components (D) and/or (E), there is attained in particular high stability in storage of the odorants according to the invention and also of an odorized fuel gas according to the invention. Stability in storage tests have shown that the warning smell of odorants according to the invention in a fuel gas remains substantially constant over a period of more than 8 months at 40° C. (incubator), cf. also the examples below. Particularly high stability in storage is attained if component (C) and one of components (D) and/or (E) are at the same time present.
• the total amount of component (E) in preferred odorants according to the invention lies in the range of from 5-500 ppm, preferably in the range of from 10-200 ppm.
• the compounds of formula (I) are stable nitroxides.
• Preferred compounds which can be used in component (E) correspond to formula (I) wherein R ⁇ H (2,2,6,6-tetramethylpiperidin-1-oxyl of formula (Ia), known under the abbreviation TEMPO) or wherein R ⁇ OH (corresponding to formula (Ib)) and are commercially available.
• the amount of odorant based on the fuel gas to be odorized lies typically in the range of from 2-100 mg/m 3 , preferably 3-50 mg/m 3 , particularly preferably 5-40 mg/m 3 and most particularly preferably 8-35 mg/m 3 .
• the odorants according to the invention and the fuel gases, in particular natural gas, containing these mixtures contain, in addition to THT (component (B)), neither tert-butyl mercaptan (TBM) nor ethyl mercaptan.
• the odorant comprises no mercaptan at all. Particularly preferably, apart from tetrahydrothiophene (component (B)), no further sulfur-containing compound is contained in the odorant according to the invention.
• Preferred odorants according to the invention comprise or consist of:
• Particularly preferred odorants according to the invention comprise:
• an odorant according to the invention comprises
• R is selected from the group consisting of H and —OH.
• the particularly preferred mixtures are distinguished by particularly high stability in storage. Partly synergistic stability improvements are observed in odorizings according to the invention on combination of hydroquinone monomethyl ether (component (C)) and at least one further component (D) and/or (E).
• component (E) in an odorant according to the invention, said compounds do not display the above-discussed drawbacks of the odorants proposed in accordance with WO 2005/103210; presumably, this is due to the presence of component (C), that is to say, the presence of the low amount of hydroquinone monomethyl ether.
• odorizings according to the invention contain or consist of
• the present invention relates also to a vessel comprising:
• an odorant according to the invention comprising component (E), wherein the odorant or (ii) a fuel gas according to the invention, containing an odorant comprising component (E), wherein the fuel gas is contacted in the vessel with a metal or metal ions or another reactant which is capable of reacting with component (E).
• Methods which are in practice particularly relevant for odorizing fuel gas having a methane content of at least 60% by weight correspond in their preferred configurations to the particularly preferred odorants according to the invention.
• an odorant according to the invention is added to a fuel gas to be odorized in an amount which causes a warning smell. Amounts of odorant that are preferably to be used, based on the amount of the fuel gas to be odorized, are specified above.
• MeAc methyl acrylate
• EtAc ethyl acrylate
• THT tetrahydrothiophene
• MeHQ hydroquinone monomethyl ether
• BHT 2,6-di-tert-butyl-p-cresol
• TEMPO 2,2,6,6-tetramethylpiperidin-1-oxyl.
• the odorants according to the invention of the following table 1 were olfactorily assessed in concentrations of 10 and 25 mg/Nm 3 of natural gas (natural gas L; methane content: approx. 85% by volume) with regard to their warning smell and their warning intensity against unodorized natural gas (blank value). These concentrations correspond to the typical concentrations of odorant in natural gas under conventional conditions.
• the test method was carried out at room temperature (about 20° C.) in such a way that the odorant is introduced into a gas flow in a tube. At the end of this 2 m-long tube (the homogenization takes place within the tube), the issuing odorized gas is olfactorily assessed by a group of trained examiners (8 to 12 persons). The assessment was carried out on a scale of from 1 (very weak/offering very little warning) to 10 (very stark/offering a great deal of warning); the specified values are average values.
• the odorants according to the invention were added to natural gas L and the odorized natural gas was olfactorily tested after specific periods of time in storage at 40° C. as described.
• the criterion for stability in storage was the significant olfactory correspondence of the stored odorized gas to the original warning smell.
• R is selected from the group consisting of H, —OH, —NH 2 , —O 2 CR 1 and —NOCR 1 , wherein R 1 represents an alkyl radical containing 1 to 4 carbon atoms, based on the total weight of the odorant.
• Specific embodiment two comprises the odorant as in specific embodiment one, comprising
• Specific embodiment three comprises the odorant as in one of the preceding specific embodiments, comprising or consisting of
• Specific embodiment four comprises the odorant as in one of the preceding specific embodiments, comprising
• Specific embodiment five comprises the odorant as in one of the preceding specific embodiments, comprising in component (E) one or more compounds of formula (I)
• R is selected from the group consisting of H and —OH.
• Specific embodiment six comprises the odorant as in one of the preceding specific embodiments, comprising
• R is selected from the group consisting of H and —OH.
• Specific embodiment seven comprises the odorant as in one of the preceding specific embodiments, comprising neither tert-butyl mercaptan (TBM) nor ethyl mercaptan.
• Specific embodiment eight comprises the odorant as in one of the preceding specific embodiments, wherein the odorant comprises no mercaptan.
• Specific embodiment nine comprises the odorant as in one of the preceding specific embodiments, wherein the odorant comprises, apart from tetrahydrothiophene (THT), no sulfur-containing compound.
• THT tetrahydrothiophene
• Specific embodiment ten comprises a fuel gas having a methane content of at least 60% by weight, comprising an odorant as defined in one of the preceding specific embodiments.
• Specific embodiment eleven comprises the fuel gas as in specific embodiment ten, characterized in that the fuel gas is natural gas.
• an odorant as in one of specific embodiments one to eight, comprising component (E), wherein the odorant or (ii) a fuel gas as in one of specific embodiments nine and ten, containing an odorant comprising component (E), wherein the fuel gas is contacted in the vessel with a metal or metal ions or another reactant which is capable of reacting with component (E).

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• 2006
  • 2006-09-22 DE DE202006014741U patent/DE202006014741U1/de not_active Expired - Lifetime
• 2007
  • 2007-09-21 WO PCT/EP2007/060057 patent/WO2008034901A1/de active Application Filing
  • 2007-09-21 PL PL07820469T patent/PL2066766T3/pl unknown
  • 2007-09-21 CN CNA2007800352668A patent/CN101517045A/zh active Pending
  • 2007-09-21 DK DK07820469.0T patent/DK2066766T3/en active
  • 2007-09-21 EP EP07820469.0A patent/EP2066766B1/de not_active Revoked
  • 2007-09-21 US US12/442,074 patent/US20110155616A1/en not_active Abandoned
  • 2007-09-21 ES ES07820469.0T patent/ES2548521T3/es active Active

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