Alkane production method

Abstract

Provided is an alkane production method wherein a continuous reaction of an alcohol and hydrogen proceeds at a low reaction pressure, carbon reduction from the alcohol can be suppressed, and the conversion rate is excellent. This alkane production method for producing an alkane from a C8-22 alcohol comprises a step in which the alcohol and hydrogen are continuously reacted under the following conditions. (i) The reaction is carried out in the presence of a zeolite carrier supporting palladium, the reaction temperature is 180°C or higher, and the hydrogen pressure is 0 MPa to 0.7 MPa in terms of gauge pressure. (ii) The space velocity (SV) of the hydrogen relative to the volume of a catalyst in which the palladium is supported on the zeolite carrier is 1200 h–1 to 2400 h–1. (iii) The space velocity (SV) of the alcohol relative to the volume of the catalyst in which the palladium is supported on the zeolite carrier is 8 h–1. (iv) The zeolite carrier is of an H-beta type or an H-ZSM-5 type, has a molar ratio (SiO2 / AL2O3) between silica (SiO2) and alumina (AL2O3) of 23 to 27, and has a palladium support quantity of 0.1 mass% to 5 mass%.

Description

Method for producing alkane

[0001] The present invention relates to a method for producing alkane.

[0002] Conventionally, methods for producing alkanes using alcohols, which are abundant in nature, as raw materials have been studied. Alkanes are chemically and thermally stable chemical substances and are used in a wide range of fields such as solvents for chemical reactions, paints, and toiletries.

[0003] Most of the alkanes currently in use are derived from petroleum and have the advantage of being inexpensive and obtainable in large quantities.

[0004] However, the use of petroleum-derived alkanes is considered to be a contributing factor to the increase in the concentration of carbon dioxide on the earth. Therefore, there is a need to produce alkanes from biomass-derived raw materials centered on plants.

[0005] As raw materials derived from plants, oils and fats such as coconut oil, palm oil, castor oil, sunflower oil, and rapeseed oil are widely used, and higher alcohols having 8 to 24 carbon atoms are produced worldwide using these as raw materials. Therefore, there is a need to produce alkanes using higher alcohols having 8 to 24 carbon atoms as raw materials.

[0006] For example, in Patent Document 1, a continuous reductive dehydroxymethylation method for preparing alkanes from primary aliphatic alcohols having 3 to 25 carbon atoms in a reactor under a pressure of 2 bar or more in the presence of hydrogen and a catalyst, wherein the dehydroxymethylation is carried out in the gas phase, is disclosed.

[0007] Japanese Patent Application Laid-Open No. 2023-524761

[0008] The method described in Patent Document 1 has problems such as requiring a hydrogen pressure of 1 MPa or more during the continuous reaction of alcohol and hydrogen. Further, in the method described in Patent Document 1, an alkane having one less carbon atom than the alcohol is produced. Therefore, methane, which is a greenhouse gas, is generated during the production of alkanes, and it was also necessary to recover methane, etc.

[0009] Therefore, the present invention provides a method for producing an alkane, which can suppress decarbonization from alcohol and has excellent conversion rate, while allowing a continuous reaction between alcohol and hydrogen to proceed at a lower reaction pressure as compared with the method described in Patent Document 1.

[0010] As a result of intensive studies, the present inventors have found that by using a catalyst in which palladium is supported on a specific zeolite carrier and continuously reacting alcohol and hydrogen under specific reaction conditions, a continuous reaction between alcohol and hydrogen can proceed at a lower reaction pressure than before, an alkane can be produced without decarbonization from alcohol, and the conversion rate is excellent. Thus, the present invention has been completed.

[0011] That is, the present invention is a method for producing an alkane by producing an alkane from an alcohol having 8 to 22 carbon atoms, the method comprising a step of continuously reacting the alcohol and hydrogen under the following conditions. (i) The reaction is carried out in the presence of a zeolite carrier supporting palladium, the reaction temperature is 180°C or higher, and the hydrogen pressure is 0 MPa or higher and 0.7 MPa or lower in gauge pressure. (ii) The space velocity (SV) of hydrogen with respect to the volume of the catalyst in which palladium is supported on the zeolite carrier is 1200 h －１ or higher and 2400 hor lower. (iii) The space velocity (SV) of the alcohol with respect to the volume of the catalyst in which palladium is supported on the zeolite carrier is 8 h －１ or lower. (iv) The zeolite carrier is of the H-beta type or the H-ZSM-5 type, and the molar ratio (SiO －１ / Al ２ O ２ ３ ２ ２ ３ ２ O ３ ３

[0012] In the method for producing alkanes of the present invention, it is preferable that the reaction temperature is 250°C or lower. Furthermore, it is preferable that the hydrogen pressure is 0.1 MPa or lower in gauge pressure. Also, the space velocity (SV) of the catalyst, in which palladium is supported on the zeolite support of the alcohol, relative to its volume is 6h. －１ Preferably the following: Also, the space velocity (SV) of the catalyst in which palladium is supported on the zeolite support for hydrogen is 1800 h⁻¹. －１ The following is preferable. Furthermore, the zeolite carrier is preferably of the H-ZSM-5 type. Furthermore, the zeolite carrier is silica (SiO ２ ) and alumina (Al ２ O ３ ) molar ratio (SiO ２ / Al ２ O ３ It is preferable that the ratio is 23. Furthermore, it is preferable that the zeolite support has a palladium loading amount of 1% by mass or less.

[0013] The present invention provides a method for producing alkanes in which a continuous reaction between alcohol and hydrogen proceeds at low reaction pressure, carbon reduction from the alcohol is suppressed, and the conversion rate is also excellent.

[0014] The present invention provides a method for producing alkanes from an alcohol having 8 to 22 carbon atoms, comprising the step of continuously reacting the alcohol with hydrogen under the following conditions: (i) The reaction is carried out in the presence of a zeolite support bearing palladium, with a reaction temperature of 180°C or higher and a hydrogen pressure of 0 MPa or higher and 0.7 MPa or lower in gauge pressure. (ii) The space velocity (SV) of hydrogen relative to the volume of the catalyst bearing palladium on the zeolite support is 1200 h⁻¹. －１ More than 2400h －１ The following applies: (iii) The space velocity (SV) of the catalyst in which palladium is supported on the zeolite support of the above alcohol is 8h －１ The following applies: (iv) The zeolite support is of the H-beta type or H-ZSM-5 type, and silica (SiO ２ ) and alumina (Al ２ O ３) molar ratio (SiO ２ / Al ２ O ３ The ratio is 23 or more and 27 or less, and the amount of palladium supported is 0.1% by mass or more and 5% by mass or less. The components of the method for producing alkanes according to the present invention will be described in detail below.

[0015] <Step of continuous reaction of alcohol and hydrogen> The present invention provides a step of continuously reacting the above-mentioned alcohol and hydrogen under the following conditions (i) to (iv) (also simply called a continuous reaction step).

[0016] (i) The reaction is carried out in the presence of a zeolite support bearing palladium, with a reaction temperature of 180°C or higher and a hydrogen pressure of 0 MPa or more and 0.7 MPa or less in gauge pressure.

[0017] [Reaction Temperature] In the continuous reaction process, the reaction temperature is 180°C or higher. By maintaining a reaction temperature of 180°C or higher, it is possible to obtain not only linear alkanes but also alkanes with branched structures.

[0018] From the viewpoint of improving the conversion rate, the above reaction temperature is preferably 190°C or higher, more preferably 200°C or higher, even more preferably 210°C or higher, and particularly preferably 220°C or higher. From the viewpoint of improving the selectivity of alkanes having a branched structure, the above reaction temperature is preferably above 200°C, more preferably 210°C or higher, and even more preferably 220°C or higher. Furthermore, from the viewpoint of improving the selectivity of alkanes with a linear structure, the above reaction temperature is preferably 200°C or lower, more preferably 190°C or lower, and even more preferably 180°C. The upper limit of the above reaction temperature is preferably 250°C or lower.

[0019] [Hydrogen Pressure] In the continuous reaction process, the hydrogen pressure is between 0 MPa and 0.7 MPa in gauge pressure.

[0020] From the viewpoint of improving the conversion rate, the hydrogen pressure is preferably 0.1 MPa or less, more preferably 0 MPa (atmospheric pressure). From the viewpoint of improving the selectivity of alkanes having a branched structure, the hydrogen pressure is preferably 0.5 MPa or less, more preferably 0.3 MPa or less, and even more preferably 0.1 MPa or less.

[0021] (ii) The space velocity (SV) of a catalyst in which palladium is supported on a hydrogen zeolite support is 1200 h⁻¹. －１ More than 2400h －１ The following applies:

[0022] [Space velocity of hydrogen (SV)] In the continuous reaction process, the space velocity of hydrogen (SV) is 1200 h. －１ More than 2400h －１ The following applies: The space velocity (SV) of hydrogen is set to 1800 h from the viewpoint of suitably improving the conversion rate. －１ Preferably, it is 1500h －１ The following is more preferable. In this specification, space velocity (SV) represents how many times the volume of the catalyst, in which palladium is supported on a zeolite support, the hydrogen or raw material (alcohol) that passes through per unit time (1 hour).

[0023] (iii) The space velocity (SV) of a catalyst in which palladium is supported on an alcohol zeolite support is 8h －１ The following applies:

[0024] [Space velocity (SV) of alcohol] In a continuous reaction process, the space velocity (SV) of alcohol is 8h －１ The following applies. By setting the space velocity (SV) of alcohol within the above range, the conversion rate can be improved. The space velocity (SV) of alcohol is set to 6h from the viewpoint of suitably improving the conversion rate. －１ The following is preferable: 3h －１ More preferably, the following, 2h －１ It is even more preferable that the following conditions apply: 1.5h －１ The following is particularly preferable: 1.2h －１ The following is most preferable:

[0025] [Alcohols] The above alcohols have 8 to 22 carbon atoms. Specific examples include 1-octanol, 1-nonanol, 1-decanol, 1-undecanol, 1-dodecanol, 1-tridecanol, 1-tetradecanol, 1-pentadecanol, 1-hexadecanol, 1-heptadecanol, 1-octadecanol, 1-nonadecanol, 1-eicosanol, 1-docosanol, etc. These alcohols used as raw materials can be used individually or in combination of two or more.

[0026] Furthermore, the method for producing alkanes according to the present invention can produce alkanes with the same number of carbon atoms as alcohols with 8 to 22 carbon atoms.

[0027] (iv) The zeolite support is of the H-beta type or H-ZSM-5 type, and silica (SiO ２ ) and alumina (Al ２ O ３ ) molar ratio (SiO ２ / Al ２ O ３ The ratio is 23 or more and 27 or less, and the amount of palladium loaded is 0.1% by mass or more and 5% by mass or less.

[0028] [Catalyst] In the continuous reaction process, a catalyst consisting of palladium supported on a zeolite support is used.

[0029] The above zeolite support is of the H-beta type or the H-ZSM-5 type. From the viewpoint of improving the conversion rate, the above zeolite support is preferably of the H-ZSM-5 type. The H-beta type means that the crystal structure is beta type (BEA type) and the cation constituting the zeolite is hydrogen, and the H-ZSM-5 type means that the crystal structure is ZSM-5 type (MFI type) and the cation constituting the zeolite is hydrogen.

[0030] The above zeolite catalyst is silica (SiO ２ ) and alumina (Al ２ O ３ ) molar ratio (SiO ２ / Al ２ O ３ The above molar ratio (SiO２ / Al ２ O ３ From the viewpoint of improving the conversion rate, it is preferable that the value is 23.

[0031] Examples of commercially available zeolite carriers include the HSZ-900 series 931HOD1A type (manufactured by Tosoh Corporation) for H-beta type, and the HSZ-800 series 822HOD1A type (manufactured by Tosoh Corporation) for H-ZSM-5 type.

[0032] The above zeolite support has a palladium loading amount of 0.1% by mass or more and 5% by mass or less. Preferably, the palladium loading amount of the above zeolite support is 2% by mass or less, and more preferably 1% by mass or less. Even with a palladium loading amount within this range, the continuous reaction process proceeds sufficiently.

[0033] One method for supporting palladium on the zeolite support is to impregnate a molded zeolite support with a solution of palladium salt prepared to a predetermined amount, dry it, and then calcine it in air at 290°C to 350°C for 2 hours. After that, reduction is carried out at 200°C to 300°C for 2 to 3 hours under a hydrogen atmosphere, or with a reagent such as sodium borohydride, to obtain a catalyst in which palladium is supported on the zeolite support. Examples of the palladium salt include palladium(II) chloride, palladium(II) acetate, palladium(II) nitrate, and palladium(II) sulfate.

[0034] [Other] In the continuous reaction process, a solvent may be used, but it is preferable not to use a solvent. If a solvent is used, it is necessary to use a solvent whose boiling point is equal to or higher than the reaction temperature of the reaction in which the alkane is obtained from the alcohol.

[0035] The equipment used in the continuous reaction process is not particularly limited; any known equipment can be selected as appropriate.

[0036] After the continuous reaction process, purification may be performed. Examples of such purification include purifying the crude product by distillation. The purification method is not particularly limited, and any known method may be used.

[0037] [Analysis Method] The production of an alkane by the method of the present invention can be confirmed by gas chromatography (GC) analysis. Specific methods may be used, such as those described in the examples of this specification.

[0038] The present invention provides a method for producing alkanes that allows for the production of alkanes with a high conversion rate. The "conversion rate" refers to the amount of alcohol consumed as a raw material. The conversion rate can be expressed by the following formula: Conversion rate (%) = 100 (%) - Percentage of alcohol used as a raw material remaining after the reaction between alcohol and hydrogen (%). If the alcohol used as a raw material is completely consumed, the conversion rate is 100%. The percentage of alcohol used as a raw material remaining after the reaction between alcohol and hydrogen (%) can be confirmed by GC (carbon dating).

[0039] In the method for producing alkanes of the present invention, the conversion rate is 10% or more. Preferably, the conversion rate is 15% or more, more preferably 30% or more, even more preferably 45% or more, even more preferably 60% or more, particularly preferably 75% or more, particularly more preferably 90% or more, and most preferably 100%.

[0040] The present invention provides a method for producing alkanes in which linear alkanes and branched alkanes, which have not been decarbonized, are to be obtained from the alcohol used as a raw material. The selectivity for the linear alkanes or the branched alkanes can be expressed by the following formulas: Selectivity for linear alkanes (%) = <[Percentage of target product (linear alkanes) (%)] / (Conversion rate)> × 100 Selectivity for branched alkanes (%) = <[Percentage of target product (branched alkanes) (%)] / (Conversion rate)> × 100

[0041] In the method for producing alkanes of the present invention, the selectivity of the linear alkane is 60% or more, or the selectivity of the branched alkane is 1% or more. The selectivity of the linear alkane is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. The selectivity of the branched alkane is preferably 5% or more, more preferably 7% or more, and even more preferably 10% or more.

[0042] This specification discloses the following: (1) This disclosure is a method for producing an alkane from an alcohol having 8 to 22 carbon atoms, comprising the step of continuously reacting the alcohol with hydrogen under the following conditions: (i) The reaction is carried out in the presence of a zeolite support bearing palladium, the reaction temperature is 180°C or higher, and the hydrogen pressure is 0 MPa or higher and 0.7 MPa or lower in gauge pressure. (ii) The space velocity (SV) of hydrogen relative to the volume of the catalyst bearing palladium on the zeolite support is 1200 h －１ More than 2400h －１ The following applies: (iii) The space velocity (SV) of the catalyst in which palladium is supported on the zeolite support of the above alcohol is 8h －１ The following applies: (iv) The zeolite support is of the H-beta type or H-ZSM-5 type, and silica (SiO ２ ) and alumina (Al ２ O ３ ) molar ratio (SiO ２ / Al ２ O ３ ) is 23 or more and 27 or less, and the amount of palladium supported is 0.1% by mass or more and 5% by mass or less. Disclosure (2) is a method for producing an alkane according to Disclosure (1), wherein the reaction temperature is 250°C or less. Disclosure (3) is a method for producing an alkane according to Disclosure (1) or (2), wherein the hydrogen pressure is 0.1 MPa or less in gauge pressure. Disclosure (4) is a method for producing an alkane according to Disclosure (4) wherein the space velocity (SV) of the catalyst in which palladium is supported on the zeolite support of the alcohol is 6h －１The method for producing an alkane described in any of the following disclosures (1) to (3). Disclosure (5) describes a method for producing an alkane in which the space velocity (SV) of the catalyst in which palladium is supported on the zeolite support of hydrogen is 1800 h. －１ The following is a method for producing an alkane as described in any of the following disclosures (1) to (4). Disclosure (6) is a method for producing an alkane as described in any of the following disclosures (1) to (5), wherein the zeolite carrier is of the H-ZSM-5 type. Disclosure (7) is a method for producing an alkane as described in any of the following disclosures (1) to (5), wherein the zeolite carrier is of the silica (SiO ２ ) and alumina (Al ２ O ３ ) molar ratio (SiO ２ / Al ２ O ３ The present disclosure (1) to (6) is a method for producing an alkane, wherein the zeolite support is 23. The present disclosure (8) is a method for producing an alkane, wherein the zeolite support has a palladium loading amount of 1% by mass or less, according to any one of the present disclosures (1) to (7).

[0043] The present invention will be further described in detail below with reference to examples, but the present invention is not limited to these examples. Compounds not specifically mentioned were used as reagents.

[0044] The following were used in the examples and comparative examples.

[0045] (Alcohol) ・C １２ OH (1-dodecanol) (Conol 20P, manufactured by Shin Nippon Rika Co., Ltd.) ・C ８ OH (1-octanol) (Conol 10WS, manufactured by Shin Nippon Rika Co., Ltd.) ・C ２２ OH (1-docosanol) (manufactured by Tokyo Chemical Industry Co., Ltd.) ・C １２ OH (75% by mass)・C １４OH (25% by mass) (Conol C1275, manufactured by Shin Nippon Rika Co., Ltd.) (Metal species) ・Palladium (Pd, product name: Palladium(II) acetate, manufactured by Tokyo Chemical Industry Co., Ltd.) ・Nickel (Ni, product name: Nickel(II) nitrate hexahydrate, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (Zeolite carrier) ・822HOD1A (HSZ-800 series, 822HOD1A type, manufactured by Tosoh Corporation) ・931HOD1A (HSZ-900 series, 931HOD1A type, manufactured by Tosoh Corporation) Note that the crystal structure and silica (SiO) are described in Tables 1 and 2. ２ ) and alumina (Al ２ O ３ ) molar ratio (SiO ２ / Al ２ O ３ ) is shown. The above molar ratio (SiO ２ / Al ２ O ３ The values ​​were based on catalog specifications.

[0046] (Comparative Example 1) 20 ml of a catalyst consisting of a prepared zeolite support (822HOD1A) carrying 1.0 mass% of palladium was packed into a SUS reaction tube with an inner diameter of 2.1 cm and a length of 15 cm, and glass beads were packed into the remaining space. The column after catalyst packing was attached to the reactor, and the hydrogen pressure (gauge pressure) was 0.1 MPa and the hydrogen space velocity was 300 h⁻¹. －１ , and the space velocity of the raw material (alcohol) is 6.0 h －１ The reaction tube was heated while flowing the mixture until the temperature reached 180°C. When using solidifying raw materials, the raw material tank and raw material supply line were heated above their melting points while the raw materials were supplied. The reaction was carried out continuously for one hour after the temperature in the reaction tube reached 180°C. After one hour, a sample was taken from the crude material recovery tank and analyzed.

[0047] (Examples 1-25, Comparative Examples 2-7) Alkanes were produced in the same manner as in Comparative Example 1, except that a continuous reaction process was carried out using the C8-C22 alcohols, metal loading amounts, metal species, and zeolite support types listed in Tables 1 and 2, and under the reaction temperature, hydrogen pressure, hydrogen space velocity (SV), and alcohol space velocity (SV) conditions listed in Tables 1 and 2. Note that the hydrogen pressure in Tables 1 and 2 is the value in gauge pressure.

[0048]

[0049]

[0050] (GC Analysis) For GC analysis, the products obtained in the examples and comparative examples were analyzed by removing water from the crude product with sodium sulfate, and then preparing the crude product as a 1% by mass hexane or xylene solution. The GC measurement conditions were as follows. The measurements were performed as follows according to the number of carbon atoms in the alcohol used as the raw material. The conversion rate and selectivity were calculated using the method described herein. The results are shown in Tables 3 and 4. <Measurement Conditions> <Measurement conditions for GC for C8-C10 analysis> Instrument: Gas chromatograph GC-2014 (manufactured by Shimadzu Corporation) Detector: FID, 335℃ Column: DB-1 (30m x 0.25mmφ x 0.25μm) Column temperature: 40℃ Injection temperature: 335℃ Carrier gas: Helium (linear velocity: 40cm / sec) Injection volume: 1.0μl (split ratio: 50) <Measurement conditions for GC for C12-C18 analysis> Instrument: Gas chromatograph GC-2014 (manufactured by Shimadzu Corporation) Detector: FID, 335℃ Column: DB-1 (30m x 0.25mmφ x 0.25μm) Column temperature: 70℃ Injection temperature: 335℃ Carrier gas: Helium (linear velocity: 40cm / sec) Injection volume: 1.0 μl (split ratio: 50) <Measurement conditions for GC analysis for C20 and above> Instrument: Gas chromatograph GC-2014 (manufactured by Shimadzu Corporation) Detector: FID, 335℃ Column: DB-1 (30 m × 0.25 mmφ × 0.25 μm) Column temperature: 100℃ Injection temperature: 335℃ Carrier gas: Helium (linear velocity: 38 cm / sec) Injection volume: 1.0 μl (split ratio: 50) <Evaluation criteria> Based on GC analysis, the following criteria were used for evaluation. ◎: Conversion rate of 15% or more, and selectivity of linear alkanes (indicated as linear-alkane selectivity in the table) of 80% or more, or selectivity of branched alkanes (indicated as branched-alkane selectivity in the table) of 10% or more. 〇: Conversion rate of 10% or more, and selectivity of linear alkanes of 60% or more, or selectivity of branched alkanes of 1% or more. ×: Does not fall under ◎ or 〇.

[0051]

[0052]

[0053] From the above examples, it was confirmed that the method for producing alkanes of the present invention allows for a continuous reaction between alcohol and hydrogen at low reaction pressure, suppresses carbon reduction from alcohol, and exhibits excellent conversion rates.

[0054] The present invention provides a method for producing alkanes in which a continuous reaction between alcohol and hydrogen proceeds at low reaction pressure, suppressing carbon loss from the alcohol, and exhibiting excellent conversion rates. The produced alkanes can be used as solvents for chemical reactions, raw materials for paints and toiletries, or as biomass raw materials.

Claims

1. A method for producing an alkane by producing an alkane from an alcohol having 8 to 22 carbon atoms, the method comprising a step of continuously reacting the alcohol with hydrogen under the following conditions. (i) The reaction is carried out in the presence of a zeolite carrier supporting palladium, the reaction temperature is 180 ° C or higher, and the hydrogen pressure is 0 MPa or higher and 0.7 MPa or lower in gauge pressure. (ii) The space velocity (SV) of hydrogen with respect to the volume of the catalyst in which palladium is supported on the zeolite carrier is 1200 h －１ or higher and 2400 h －１ or lower. (iii) The space velocity (SV) of the alcohol with respect to the volume of the catalyst in which palladium is supported on the zeolite carrier is 8 h －１ or lower. (iv) The zeolite carrier is of the H-beta type or the H-ZSM-5 type, and the molar ratio (SiO ２ ) / (Al ２ O ３ ) of silica (SiO ２ ) to alumina (Al ２ O ３ ) is 23 or higher and 27 or lower, and the supported amount of palladium is 0.1% by mass or higher and 5% by mass or lower.

2. The method for producing an alkane according to claim 1, wherein the reaction temperature is 250°C or lower.

3. The method for producing an alkane according to claim 1 or 2, wherein the hydrogen pressure is 0.1 MPa or less in gauge pressure.

4. The space velocity (SV) of the catalyst in which the alcohol is supported on the zeolite carrier with palladium is 6h －１ The method for producing an alkane according to claim 1 or 2, which is as follows:

5. The space velocity (SV) of the hydrogen catalyst with palladium supported on the zeolite carrier is 1800 h. －１ The method for producing an alkane according to claim 1 or 2, which is as follows:

6. The method for producing an alkane according to claim 1 or 2, wherein the zeolite carrier is of type H-ZSM-5.

7. The zeolite support is silica (SiO ２ ) and alumina (Al ２ O ３ ) molar ratio (SiO ２ / Al ２ O ３ A method for producing an alkane according to claim 1 or 2, wherein ) is 23.

8. The method for producing an alkane according to claim 1 or 2, wherein the zeolite carrier has a palladium loading amount of 1% by mass or less.

Images