Cycloalkane compound dehydrogenation method, dehydrogenation catalyst and preparation method and application of dehydrogenation catalyst

Abstract

The invention provides a cycloalkane compound dehydrogenation method, a dehydrogenation catalyst as well as a preparation method and application of the dehydrogenation catalyst. The catalyst comprises an alumina carrier and an active component platinum loaded on the carrier, wherein the active component platinum is distributed on the outer surface of the carrier within the range of 0.2-0.7 time of the radius of the carrier. When the catalyst is used for dehydrogenation of cycloalkane (methyl cyclohexane), the catalyst shows excellent dehydrogenation reaction performance (the conversion rate is greater than 95%, and the selectivity is greater than 99%) under the condition of lower reaction temperature (350 DEG C).

Description

Technical Field

[0001] The present invention relates to a dehydrogenation catalyst, a preparation method and application thereof, and a method for dehydrogenating cycloalkane compounds and a dehydrogenation catalyst, a preparation method and application thereof. Background Art

[0002] In the context of the global response to climate change, the development of hydrogen energy has become a basic consensus of the international community. At present, the bottleneck of large-scale application of hydrogen lies in the efficient and safe storage and transportation of hydrogen energy. Organic liquid hydrogen storage is an emerging technology that realizes hydrogen energy storage by using unsaturated liquid organic matter to react with hydrogen to form saturated hydrogenated organic matter, which realizes the safe storage and transportation of hydrogen at normal temperature and pressure.

[0003] The dehydrogenation process of the hydrogen storage liquid consumes a lot of energy. The use of highly active catalysts is conducive to lowering the reaction temperature and reducing the energy consumption of dehydrogenation. Platinum-based catalysts are currently the mainstream dehydrogenation catalysts, but the high price of platinum metal and limited surface reserves are not conducive to the marketization of this hydrogen storage technology. Reducing the platinum content of the catalyst and increasing the utilization rate of platinum in the catalyst are the main technical means currently used. Nakaya et al. (ACS Catalysis, 2020, 10, 5163-5172) prepared a variety of Pt alloy catalysts with SiO2 as the carrier, hoping to reduce the amount of precious metal Pt, and systematically studied the catalytic dehydrogenation performance of the catalyst for methylcyclohexane. The results show that the Pt loading of the catalyst they prepared is as high as 3wt%, and the catalytic dehydrogenation conversion rate of methylcyclohexane is only 70% at 300°C.

[0004] CN112076748A discloses a dehydrogenation catalyst, in which the Pt element in the active component accounts for 1% to 3% of the weight of Al2O3. The catalyst has high activity and selectivity in the organic liquid phase dehydrogenation process.

[0005] CN 115485064A discloses a method of achieving high dispersion of active metals on a carrier by means of carrier sulfidation modification, thereby improving the catalytic activity and selectivity of the catalyst. Summary of the invention

[0006] The purpose of the present invention is to provide a dehydrogenation catalyst with a reasonable distribution of active species on a carrier and a preparation method thereof. By regulating the distribution of active species, the present invention not only avoids the active species from being gathered in large quantities on the outer layer of the carrier, resulting in a large number of large-sized, low-activity active particles formed during calcination, but also avoids the active species from being mainly located inside the carrier, so that the internal diffusion resistance reduces the availability of the active species, thereby achieving the effect of reducing the amount of active metal used and improving the catalytic performance.

[0007] The inventors of the present invention found during the research process that due to the large size of the hydrogen storage liquid molecules, the dehydrogenation reaction occurs preferentially on the active metal on the catalyst surface. However, if the active metal is only loaded on the surface, the active metal dispersion will be poor and the reaction catalytic activity will be low. If the active metal is loaded inside the carrier, although the dispersion of the active metal can be improved, it is necessary to simultaneously consider the effect of the diffusion resistance in the catalyst particles on the availability of the active metal inside the carrier. Therefore, the present invention proposes to regulate the catalyst preparation process to achieve a reasonable distribution of active species along the radial direction of the carrier to obtain a highly active dehydrogenation catalyst.

[0008] In order to achieve the above object, the present invention adopts an acidic regulator to improve the preparation process of the catalyst, and obtains a dehydrogenation catalyst in which active species are reasonably distributed along the radial direction of the carrier (active components are distributed within the range of 0.2-0.7 times the radius of the carrier from the outer surface of the carrier). When the catalyst is used for dehydrogenation of cycloalkane (methylcyclohexane), it exhibits excellent dehydrogenation reaction performance (conversion rate>95%, selectivity>99%) under relatively low reaction temperature conditions (350°C).

[0009] The first aspect of the present invention provides a dehydrogenation catalyst, which includes an alumina carrier and an active component platinum loaded on the carrier; wherein the active component platinum is distributed within the range of 0.2-0.7 times the radius of the carrier from the outer surface of the carrier.

[0010] A second aspect of the present invention provides a method for preparing a dehydrogenation catalyst, the method comprising the following steps:

[0011] (1) preparing an aqueous solution containing platinum ions, wherein the concentration of platinum ions is 5-20 mmol / L and the concentration of the organic complex is 1-5 mmol / L;

[0012] (2) adding an acidity regulator to the ionic dispersion of step (1) so that the pH value of the solution is 2.0-5.5;

[0013] (3) contacting the solution obtained in step (2) with an alumina support source, and drying to obtain a catalyst precursor;

[0014] (4) Calcinate and reduce the catalyst precursor.

[0015] The third aspect of the present invention provides a dehydrogenation catalyst obtained by the preparation method of the present invention.

[0016] The fourth aspect of the present invention provides use of the dehydrogenation catalyst of the present invention in the dehydrogenation of hydrocarbons, alcohols or ketones.

[0017] A fourth aspect of the present invention provides a method for dehydrogenating a cycloalkane compound, wherein the cycloalkane compound is dehydrogenated in the presence of a dehydrogenation catalyst, wherein the dehydrogenation catalyst comprises the dehydrogenation catalyst described in the present invention.

[0018] In the present invention, the above technical effects are achieved by combining organic ligand chelation and impregnation solution acidity control. When the solution acidity is relatively high (pH>5.5), during the impregnation process, only the outer surface of the carrier can be protonated, and the active ions can only be adsorbed on the outside of the carrier, so that the cross-sectional morphology of the catalyst obtained by the final calcination is as follows: Figure 1 As shown, no catalyst layer was observed inside the carrier. When the pH value is 2-5.5, combined with the chelation of organic ligands, some free protons can diffuse into the interior of the carrier, making the inner surface of the carrier protonated and capable of adsorbing active ions; by adjusting the pH value of the solution, the protonation degree of the inner surface of the carrier can be controlled, thereby achieving the purpose of regulating the reasonable distribution of active species along the radial direction of the carrier and obtaining the desired catalyst (such as Figure 2 When the solution acidity is too low (pH < 2), the inner and outer surfaces of the carrier are fully protonated, and the active ions are adsorbed on both the inner and outer surfaces of the carrier. The resulting catalyst exhibits a uniform structure (as shown in Figure 3 shown).

[0019] The catalyst of the present invention has the advantage that active species are reasonably distributed along the radial direction of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a cross-sectional view of the catalyst obtained in Comparative Example 2;

[0021] Figure 2 This is a cross-sectional view of the catalyst obtained in Example 1;

[0022] Figure 3 This is a cross-sectional view of the catalyst obtained in Comparative Example 1. DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0024] The present invention provides a dehydrogenation catalyst, which comprises an alumina carrier and an active component platinum loaded on the carrier; wherein the active component platinum is distributed within the range from the outer surface of the carrier to 0.2-0.7 times of the radius of the carrier, preferably distributed in steps within the range from the outer surface of the carrier to 0.2 times, 0.25 times, 0.3 times, 0.35 times, 0.4 times, 0.45 times, 0.5 times, 0.55 times, 0.6 times, 0.65 times or 0.7 times of the radius of the carrier.

[0025] According to a preferred embodiment of the present invention, based on the total mass of the catalyst, the platinum content is 0.1%-1.2%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%. The catalyst of the present invention can significantly reduce the platinum content and achieve higher selectivity under lower platinum content conditions.

[0026] According to a preferred embodiment of the present invention, the active component platinum is present in a metallic state.

[0027] The catalysts having the above-mentioned characteristics of the present invention can achieve the purpose of the present invention, and there is no special requirement for their preparation methods. According to the present invention, a preparation method of a dehydrogenation catalyst is provided, which comprises the following steps:

[0028] (1) preparing an aqueous solution containing platinum ions, wherein the concentration of platinum ions is 5-20 mmol / L and the concentration of the organic complex is 1-5 mmol / L;

[0029] (2) adding an acidity regulator to the ionic dispersion of step (1) so that the pH value of the solution is 2.0-5.5;

[0030] (3) contacting the solution obtained in step (2) with an alumina support source, and drying to obtain a catalyst precursor;

[0031] (4) Calcinate and reduce the catalyst precursor.

[0032] In the present invention, the organic complex can be selected from a wide range of types. For the present invention, the organic complex is preferably at least one of acetylacetone, oxalic acid, malonic acid and succinic acid.

[0033] In the present invention, there is no special requirement for the calcination reduction conditions, and the calcination conditions commonly used in the prior art can be used in the present invention. For example, the general calcination conditions of the present invention include: air atmosphere, 500°C, reaction for 6 hours, but it is not limited to this embodiment, which is only used as an exemplary description.

[0034] Common reduction conditions in the prior art can be used in the present invention. For example, general reduction conditions include: hydrogen atmosphere, 350° C. reaction for 10 hours, but it is not limited to this embodiment and is only used as an exemplary description.

[0035] According to a preferred embodiment of the present invention, step (3) comprises: adsorbing the solution obtained in step (2) onto an alumina carrier by a solution impregnation method, and drying to obtain a catalyst precursor.

[0036] In the present invention, there is no special requirement for the type of Pt source. The Pt source described in the present invention includes but is not limited to at least one of chloroplatinic acid, sodium chloroplatinate and potassium chloroplatinate.

[0037] In the present invention, the acidity regulator has a wide range of optional types. According to a preferred embodiment of the present invention, the acidity regulator includes but is not limited to at least one of hydrochloric acid, nitric acid, citric acid, hydrobromic acid, perchloric acid and acetic acid, preferably acetic acid and / or perchloric acid.

[0038] According to the present invention, it is preferred that the platinum element ion solution is in contact with the alumina carrier source under light-proof conditions for 8-12 hours, and the contact temperature is 40-60°C.

[0039] In the present invention, there is no special requirement for the drying conditions. For the present invention, the drying conditions of the catalyst precursor are exemplarily described as follows: temperature 80-150° C., time 12-24 h, but this is not intended to limit the scope of the present invention.

[0040] The present invention provides a dehydrogenation catalyst obtained by the preparation method of the present invention.

[0041] The dehydrogenation catalyst obtained by the method of the present invention has the following characteristics.

[0042] The dehydrogenation catalyst prepared by the present invention comprises an alumina carrier and an active component platinum supported on the carrier; wherein the active component platinum is distributed within the range from the outer surface of the carrier to 0.2-0.7 times of the radius of the carrier, preferably distributed step by step within the range from the outer surface of the carrier to 0.2 times, 0.25 times, 0.3 times, 0.35 times, 0.4 times, 0.45 times, 0.5 times, 0.55 times, 0.6 times, 0.65 times or 0.7 times of the radius of the carrier.

[0043] The dehydrogenation catalyst prepared by the present invention has a platinum content of 0.1%-1.2%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, based on the total mass of the catalyst. The catalyst of the present invention can significantly reduce the platinum content and achieve higher selectivity under the condition of lower platinum content.

[0044] In the dehydrogenation catalyst prepared by the present invention, the active component platinum exists in a metal state.

[0045] The present invention provides the use of the dehydrogenation catalyst of the present invention in the dehydrogenation of hydrocarbons, alcohols or ketones, especially the dehydrogenation of cycloalkanes. The dehydrogenation catalyst of the present invention has the advantage of high catalytic activity in the above-mentioned dehydrogenation reaction.

[0046] The present invention provides a method for dehydrogenating a cycloalkane compound. The cycloalkane compound is dehydrogenated in the presence of a dehydrogenation catalyst. The dehydrogenation catalyst comprises any one of the dehydrogenation catalysts described in the present invention.

[0047] According to a preferred embodiment of the present invention, preferably, the cycloalkane compound is at least one of methylcyclohexane, cyclohexane, dimethylcyclohexane, ethylcyclohexane, tetralin and decalin.

[0048] The present invention will be described in detail below through examples. In the following examples, the metal content parameter is measured by ICP method; the catalyst specific surface area is obtained by nitrogen adsorption-desorption instrument test, and the alumina carrier is a commercial product.

[0049] The distribution of the catalyst along the radial direction of the carrier was detected using an optical microscope.

[0050] Example 1

[0051] (1) Take a certain amount of chloroplatinic acid to prepare an aqueous solution with a platinum ion concentration of 15 mmol / L and a succinic acid concentration of 3 mmol / L. Add hydrochloric acid aqueous solution to make the pH value of the platinum-containing solution 2.6. Then, the platinum-containing solution and the alumina support are placed in contact at 40°C in the dark for 10 hours. Then, the alumina support loaded with the precursor is placed in an oven at 110°C for 14 hours.

[0052] (2) The metal element-containing precursor is calcined in an air atmosphere at 450° C. for 4 h, with the temperature rising rate of the calcination furnace being 5° C. / min.

[0053] (3) 5 g of the calcined product was placed in a tubular reactor for reduction at a temperature of 350°C for 4 h.

[0054] The ICP test of the obtained catalyst showed that the platinum content was 0.7 wt %, and the active components were distributed in the range from the outer surface of the carrier to 0.5 times the radius of the carrier.

[0055] Dehydrogenation of methylcyclohexane to produce hydrogen:

[0056] In the reaction tube, the catalyst loading amount is 1 g, the reaction temperature is 350 ° C, and the mass space velocity of methylcyclohexane is 2 h -1 The product after 12 hours of reaction was analyzed, and the conversion rate of methylcyclohexane was 96.8%, and the toluene selectivity was 99.3%.

[0057] Figure 2 This is a cross-sectional view of the catalyst obtained in Example 1. The white color is the alumina carrier, and the gray color is the loaded active metal. The active components are distributed from the outer surface of the carrier to 0.5 times the radius of the carrier.

[0058] Example 2

[0059] (1) A certain amount of sodium chloroplatinate is prepared into an aqueous solution with a platinum ion concentration of 19 mmol / L and an oxalic acid concentration of 4.9 mmol / L. A nitric acid aqueous solution is added to make the pH value of the platinum-containing solution 2.0. Then, the platinum-containing solution is allowed to contact with the alumina support at 55°C in the dark for 8 hours. Subsequently, the alumina support loaded with the precursor is placed in an oven at 140°C for 18 hours.

[0060] (2) The metal element-containing precursor is calcined in an air atmosphere at 450° C. for 4 h, with the temperature rising rate of the calcination furnace being 5° C. / min.

[0061] (3) 5 g of the calcined product was placed in a tubular reactor for reduction at a temperature of 350°C for 4 h.

[0062] The ICP test of the obtained catalyst showed that the platinum content was 0.7 wt %, and the active components were distributed in the range from the outer surface of the carrier to 0.7 times the radius of the carrier.

[0063] Dehydrogenation of methylcyclohexane to produce hydrogen:

[0064] In the reaction tube, the catalyst loading amount is 1 g, the reaction temperature is 350 ° C, and the mass space velocity of methylcyclohexane is 2 h -1 The product after 12 hours of reaction was analyzed, and the conversion rate of methylcyclohexane was 96.3%, and the toluene selectivity was 99.1%.

[0065] Example 3

[0066] (1) Take a certain amount of potassium chloroplatinate to prepare an aqueous solution with a platinum ion concentration of 6 mmol / L and an acetylacetone concentration of 1 mmol / L. Add acetic acid aqueous solution to make the pH value of the platinum-containing solution 5.4. Then, the platinum-containing solution and the alumina support are allowed to contact at 44°C in the dark for 12 hours. Then, the alumina support loaded with the precursor is placed in an oven at 100°C for 24 hours.

[0067] (2) The metal element-containing precursor is calcined in an air atmosphere at 450° C. for 4 h, with the temperature rising rate of the calcination furnace being 5° C. / min.

[0068] (3) 5 g of the calcined product was placed in a tubular reactor for reduction at a temperature of 350°C for 4 h.

[0069] The ICP test of the obtained catalyst showed that the platinum content was 0.7 wt %, and the active components were distributed in the range from the outer surface of the carrier to 0.2 times the radius of the carrier.

[0070] Dehydrogenation of methylcyclohexane to produce hydrogen:

[0071] In the reaction tube, the catalyst loading amount is 1 g, the reaction temperature is 350 ° C, and the mass space velocity of methylcyclohexane is 2 h-1 The product after 12 hours of reaction was analyzed, and the conversion rate of methylcyclohexane was 95.5%, and the toluene selectivity was 99.3%.

[0072] Example 4

[0073] (1) Take a certain amount of chloroplatinic acid to prepare an aqueous solution with a platinum ion concentration of 15 mmol / L and a succinic acid concentration of 3 mmol / L. Add a perchloric acid aqueous solution to make the pH value of the platinum-containing solution 3.0. Then, the platinum-containing solution and the alumina support are placed in contact at 40°C in the dark for 10 hours. Then, the alumina support loaded with the precursor is placed in an oven at 110°C for 14 hours.

[0074] (2) The metal element-containing precursor is calcined in an air atmosphere at 450° C. for 4 h, with the temperature rising rate of the calcination furnace being 5° C. / min.

[0075] (3) 5 g of the calcined product was placed in a tubular reactor for reduction at a temperature of 350°C for 4 h.

[0076] The ICP test of the obtained catalyst showed that the platinum content was 0.65wt%, and the active components were distributed in the range from the outer surface of the carrier to 0.4 times the radius of the carrier.

[0077] Dehydrogenation of methylcyclohexane to produce hydrogen:

[0078] In the reaction tube, the catalyst loading amount is 1 g, the reaction temperature is 350 ° C, and the mass space velocity of methylcyclohexane is 2 h -1 The product after 12 hours of reaction was analyzed, and the conversion rate of methylcyclohexane was 97.1%, and the toluene selectivity was 99.4%.

[0079] Example 5

[0080] (1) Take a certain amount of chloroplatinic acid to prepare an aqueous solution with a platinum ion concentration of 15 mmol / L, a succinic acid concentration of 2 mmol / L, and an acetylacetone concentration of 1 mmol / L. Add an aqueous perchloric acid solution to make the pH value of the platinum-containing solution 3.0. Then, the platinum-containing solution and the alumina support are allowed to contact for 10 hours at 40°C in the dark. Subsequently, the alumina support loaded with the precursor is placed in an oven at 110°C for 14 hours.

[0081] (2) The metal element-containing precursor is calcined in an air atmosphere at 450° C. for 4 h, with the temperature rising rate of the calcination furnace being 5° C. / min.

[0082] (3) 5 g of the calcined product was placed in a tubular reactor for reduction at a temperature of 350°C for 4 h.

[0083] The ICP test of the obtained catalyst showed that the platinum content was 0.65wt%, and the active components were distributed in the range from the outer surface of the carrier to 0.6 times the radius of the carrier.

[0084] Dehydrogenation of methylcyclohexane to produce hydrogen:

[0085] In the reaction tube, the catalyst loading amount is 1 g, the reaction temperature is 350 ° C, and the mass space velocity of methylcyclohexane is 2 h -1 The product after 12 hours of reaction was analyzed, and the conversion rate of methylcyclohexane was 97.3%, and the toluene selectivity was 99.4%.

[0086] Comparative Example 1

[0087] The method of Example 1 is followed, except that aqueous hydrochloric acid is added to make the pH value of the platinum-containing solution 1.5.

[0088] The ICP test of the obtained catalyst showed that the platinum content was 0.7wt% and the active components were evenly distributed on the carrier.

[0089] The conversion of methylcyclohexane was 93.9%, and the selectivity of toluene was 98.6%.

[0090] Figure 3 This is a cross-sectional view of the catalyst obtained in Comparative Example 1. The white part is the alumina carrier, and the gray part is the loaded active metal. The active components are evenly distributed on the carrier.

[0091] Comparative Example 2

[0092] The method of Example 2 is followed, except that aqueous hydrochloric acid is added to make the pH value of the platinum-containing solution 6.3.

[0093] The ICP test of the obtained catalyst showed that the platinum content was 0.7wt% and the active components were distributed on the outer surface of the carrier.

[0094] The conversion of methylcyclohexane was 93.5%, and the selectivity of toluene was 98.5%.

[0095] Figure 1 This is a cross-sectional view of the catalyst obtained in Comparative Example 2. The white color is the alumina carrier, and the gray color is the loaded active metal. The active components are mainly present on the outer surface of the carrier.

[0096] Comparative Example 3

[0097] The method of Example 1 was followed, except that succinic acid was not added, and the other conditions were the same.

[0098] The ICP test of the obtained catalyst showed that the platinum content was 0.7 wt %, and the active components were distributed in the range from the outer surface of the carrier to 0.18 times the radius of the carrier.

[0099] Dehydrogenation of methylcyclohexane to produce hydrogen:

[0100] In the reaction tube, the catalyst loading amount is 1 g, the reaction temperature is 350 ° C, and the mass space velocity of methylcyclohexane is 2 h -1 The product after 12 hours of reaction was analyzed, and the conversion rate of methylcyclohexane was 94.0%, and the toluene selectivity was 98.7%.

[0101] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various specific technical features in any suitable manner. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A dehydrogenation catalyst, characterized in that The catalyst comprises an aluminum oxide carrier and an active component platinum loaded on the carrier; wherein the active component platinum is distributed within the range of 0.2 to 0.7 times of the carrier radius from the outer surface of the carrier.

2. The dehydrogenation catalyst according to claim 1, wherein The platinum content is 0.1%-1.2% based on the total mass of the catalyst; and / or The active component platinum exists in a metallic state.

3. A method for preparing a dehydrogenation catalyst, characterized in that: The method comprises the following steps: (1) preparing an aqueous solution containing platinum ions, wherein the concentration of platinum ions is 5-20 mmol / L and the concentration of the organic complex is 1-5 mmol / L; (2) adding an acidity regulator to the ionic dispersion of step (1) so that the pH value of the solution is 2.0-5.5; (3) contacting the solution obtained in step (2) with an alumina support source, and drying to obtain a catalyst precursor; (4) Calcinate and reduce the catalyst precursor.

4. The preparation method according to claim 3, wherein The organic complex in step (1) is at least one of acetylacetone, oxalic acid, malonic acid and succinic acid; Step (3) comprises: adsorbing the solution obtained in step (2) onto an alumina carrier by a solution impregnation method, and drying to obtain a catalyst precursor.

5. The preparation method according to claim 3, wherein: The Pt source is selected from at least one of chloroplatinic acid, sodium chloroplatinate and potassium chloroplatinate; and / or The acidity regulator is selected from at least one of hydrochloric acid, nitric acid, citric acid, hydrobromic acid, perchloric acid and acetic acid, preferably acetic acid and / or perchloric acid.

6. The preparation method according to any one of claims 3 to 5, wherein: In step (3), the solution is contacted with the alumina carrier source under light-proof conditions for 8-12 hours at a contact temperature of 40-60°C.

7. According to the preparation method of claims 3-6, the drying conditions of the catalyst precursor include: Temperature 80-150℃, time 12-24h.

8. The dehydrogenation catalyst obtained by the preparation method according to any one of claims 3 to 7.

9. Use of the dehydrogenation catalyst according to any one of claims 1 to 2 and 8 in the dehydrogenation of hydrocarbons, alcohols or ketones.

10. A method for dehydrogenating a cycloalkane compound, comprising dehydrogenating the cycloalkane compound in the presence of a dehydrogenation catalyst, characterized in that: The dehydrogenation catalyst comprises the dehydrogenation catalyst according to any one of claims 1 to 2 and 8; Preferably, the cycloalkane compound is at least one of methylcyclohexane, cyclohexane, dimethylcyclohexane, ethylcyclohexane, tetralin and decalin.

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