Preparation method and application of organic acid modified aluminum metaphosphate supported nickel-palladium catalyst

Abstract

The application discloses a preparation method and application of an organic acid modified aluminum metaphosphate supported nickel-palladium catalyst. A carrier Al(PO3)3, 4-trifluoromethyl salicylic acid (TFMSA), a nickel source and a palladium source are added into acetone, a suspension obtained by stirring at room temperature is dried in a vacuum drying box after removing the solvent acetone by rotary evaporation, and the obtained solid is ground into a solid powder by using a mortar. The solid powder is calcined in a tube furnace under an inert atmosphere and at a specified temperature, and is reduced under H2 atmosphere and at a specified temperature to obtain a black solid powder, which is the organic acid modified aluminum metaphosphate supported nickel-palladium catalyst and is recorded as NiPd-TFMSA / Al(PO3)3. The application also discloses an application of the organic acid modified aluminum metaphosphate supported nickel-palladium catalyst in catalytic hydrogenolysis of lignite and model compounds thereof.

Description

Technical Field

[0001] This invention relates to the field of catalytic hydrogenation conversion catalyst preparation technology, and in particular to a method for preparing and applying an organic acid-modified aluminum metaphosphate supported nickel-palladium catalyst. Background Technology

[0002] Lignite resources are abundant, accounting for 13% of total coal reserves. However, its low calorific value, high moisture content, high ash content, poor thermal stability, and susceptibility to weathering mean that most lignite is used for local combustion in power generation, limiting its application as a raw material for chemical production and causing serious environmental pollution problems.

[0003] The utilization of lignite as a chemical raw material should develop in the direction of cleanliness, low carbonization, and high value, and breaking through the key core technologies for the targeted conversion of lignite into high-value chemicals is crucial.

[0004] Lignite's organic macromolecules are rich in aromatic ring structures, serving as important precursors for many aromatic compounds. These aromatic ring units are primarily linked by CO or C-C bridges, with CO bridges being the most abundant. The aromatic rings contain various alkyl side chains and oxygen-containing functional groups. The selective and efficient cleavage of the CO and C-C bridges connecting the aromatic rings is a key step in achieving high yields of aromatic compounds. Therefore, based on the structural characteristics and good reactivity of lignite organic matter, utilizing appropriate catalytic cleavage techniques to break the CO bridges in lignite can effectively convert the aromatic ring structures in lignite into aromatic compounds.

[0005] The cracking of CO bridging bonds in lignite can be achieved through catalytic hydrocracking, a key reaction in direct coal liquefaction (DCL). DCL processes are subject to harsh conditions (400-450℃ and 15-30 MPa pressure), and commonly used catalysts are low-activity iron-based catalysts. Therefore, developing highly active and selective catalysts to selectively hydrocrackle CO bridging bonds in lignite under reaction conditions less favorable than DCL is a crucial pathway for the directional conversion of lignite into aromatic chemicals. Supported metal catalysts exhibit good activity for the hydrocracking of CO bridging bonds in lignite and related model compounds, but they also lead to the hydrogenation of aromatic rings, producing aromatic compounds along with hydrogenated aromatic ring products, resulting in product complexity and difficulties in subsequent fine separation. Therefore, selecting suitable active precursors and supports, and controlling the active sites of the catalyst, is key to preparing highly active and selective catalysts for the cracking of CO bridging bonds in lignite and related model compounds, and is also one of the challenges.

[0006] The choice of support has a significant impact on supported metal catalysts. Aluminum metaphosphate (Al(PO3)3) contains a large number of Lewis acid sites, which can activate C(sp) through the formation of potential phosphate phenyl species. 2The presence of the -O bond facilitates the breaking of CO bridge bonds, and aluminum metaphosphate can inhibit metal oxidation to some extent, making it a potentially excellent support for hydrocracking catalysts. Nickel-based catalysts are widely used in catalytic hydrogenation processes due to their high activity, strong tunability, good stability, and low cost, while palladium-based catalysts are widely used in various catalytic hydrogenation conversion systems due to their excellent hydrogen activation ability, but they may also generate undesirable deep hydrogenation side reactions. The interaction between the two active components, nickel and palladium, can improve the activity and selectivity of the catalyst, leveraging their respective advantages to achieve a synergistic effect on the breaking of CO bridge bonds. The acidic active sites of the catalyst play a crucial role in the breaking of CO bridge bonds and can be modified and regulated by organic acids. 4-Trifluoromethylsalicylic acid (TFMSA), as a hydrothermally stable organic acid, can improve the compactness between the metal and acidic sites, change the environment near the catalyst interface, enhance the dispersibility of metal nanoparticles, and regulate the entry of reactants into the catalytic sites, thereby improving the catalytic activity of the catalyst for the breaking of CO bridge bonds. Considering both the catalytic hydrocracking activity and selectivity, the preparation of TFMSA-modified NiPd / Al(PO3)3 catalysts for the highly selective hydrocracking of lignite and its related model compounds with CO bridging bonds has great potential to obtain high-value-added aromatic chemicals. Summary of the Invention

[0007] Technical problems to be solved:

[0008] To address the shortcomings of existing technologies, this application provides a method for preparing and applying an organic acid-modified aluminum metaphosphate supported nickel-palladium catalyst. This method solves the problems of complex product composition and low selectivity of aromatic products caused by excessive hydrogenation during the hydrocracking of lignite and its model compounds by Pd-based and Ni-based catalysts. The catalyst is applied to the catalytic hydrocracking of CO bridging bonds in lignite and related model compounds to obtain high-value-added aromatic compounds from lignite. The catalyst preparation process is relatively simple and safe.

[0009] Technical solution:

[0010] To achieve the above objectives, this application provides the following technical solution:

[0011] A method for preparing an organic acid-modified aluminum metaphosphate supported nickel-palladium catalyst, comprising the following steps:

[0012] Step 1: Prepare the carrier Al(PO3)3 : 4-trifluoromethylsalicylic acid TFMSA : nickel source : palladium source according to the mass ratio of 1 part : 0-20 parts : 6-10 parts : 2-6 parts. Add the carrier Al(PO3)3, 4-trifluoromethylsalicylic acid TFMSA, nickel source and palladium source to acetone, and stir at 500 rpm for 4-24 hours at room temperature. Remove the solvent acetone from the suspension by rotary evaporation, and then dry it in a vacuum drying oven at 70°C for 2-6 hours. Grind the obtained solid into a solid powder with a particle size of 60-200 mesh using a mortar.

[0013] Step 2: The solid powder obtained in the previous step is heated to the specified temperature in a tube furnace under an inert atmosphere at a heating rate of 2-10℃ / min, and calcined and held at the temperature for 1-4 hours to obtain solid powder.

[0014] Step 3: The solid powder obtained in step 2 is heated to the specified temperature under H2 atmosphere at a heating rate of 2-10℃ / min and reduced for 1-4h. The H2 flow rate is 10-100mL / min. The resulting black solid powder is the organic acid modified aluminum metaphosphate supported nickel palladium catalyst, denoted as NiPd-TFMSA / Al(PO3)3.

[0015] Furthermore, in the first step, the support is aluminum metaphosphate Al(PO3)3, the nickel source is nickel acetylacetone, and the palladium source is palladium acetylacetone. The mass-to-liquid ratio of the support Al(PO3)3 to acetone is 1g:20mL.

[0016] Furthermore, in the second step, the inert atmosphere is N2, and the specified temperature is 400–700°C.

[0017] Furthermore, the specified temperature in the third step is 300–600°C.

[0018] This application also discloses the application of the organic acid-modified aluminum metaphosphate supported nickel-palladium catalyst prepared by the above preparation method in the catalytic hydrocracking of lignite and its model compounds.

[0019] Furthermore, 1-10 parts of the reaction substrate, 0.1-0.5 parts of NiPd-TFMSA / Al(PO3)3, and 50-200 parts of solvent were added together to a magnetically stirred high-pressure reactor according to the mass ratio. After purging the air three times with nitrogen, hydrogen gas was introduced at 0.5-2 MPa, and the reaction was carried out at 140-200℃ for 1-4 hours. After the reaction was completed, the reactor was cooled to room temperature and the pressure was released. The supernatant was then removed and qualitative and quantitative analysis was performed using GC-MS and GC.

[0020] Furthermore, the reaction substrate is a compound containing a CO-bridged bond, specifically lignite and one or more of diphenyl ether, benzylphenyl ether, dibenzyl ether, phenoxyethylbenzene, 2-phenoxynaphthalene, 2,2'-dinaphthalene ether and 2-naphthylbenzyl ether.

[0021] Furthermore, the solvent is one or more of methanol, ethanol, isopropanol, n-hexane, and 1,4-dioxane.

[0022] Beneficial effects:

[0023] This application provides a method for preparing and applying an organic acid-modified aluminum metaphosphate supported nickel-palladium catalyst, which has the following advantages: The preparation method of the NiPd-TFMSA / Al(PO3)3 catalyst of this invention is simple, safe, energy-saving and efficient. It has high activity and high selectivity for the hydrogenation cracking of CO bridging bonds in lignite and its related model compounds, so as to obtain high-value-added aromatic compounds from lignite. Through the hydrogenation cracking of CO bonds in lignite and its related model compounds, the yield of aromatic compounds is higher than 60% and the selectivity is higher than 80%, which solves the problem of low selectivity and complex product composition of aromatic compounds caused by excessive hydrogenation of traditional Pd-based and Ni-based catalysts. Attached Figure Description

[0024] Figure 1 The XRD patterns of the support and different catalysts in this application are shown below.

[0025] Figure 2 The images show the SEM, HRTEM, and SEM-EDS images of the NiPd-TFMSA / Al(PO3)3 catalyst of this application; where (a) is the SEM image of NiPd-TFMSA / Al(PO3)3, (b) is the HRTEM image of NiPd-TFMSA / Al(PO3)3 (5 nm, inset shows the lattice fringes of Ni and Pd), (c) is the HRTEM image of NiPd-TFMSA / Al(PO3)3 (20 nm, inset shows the metal particle size distribution), and (d) is the SEM-EDS image of NiPd-TFMSA / Al(PO3)3.

[0026] Figure 3 This is a graph showing the effect of catalyst calcination temperature on the catalytic hydrogenation cracking of phenyl benzyl ether.

[0027] Figure 4 This is a graph showing the effect of the NiPd ratio on the catalytic hydrogenation cracking of phenyl benzyl ether in this application;

[0028] Figure 5 This figure shows the effect of TFMSA addition on the catalytic hydrocracking of phenyl benzyl ether. Detailed Implementation

[0029] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0030] Example 1:

[0031] A method for preparing an organic acid-modified aluminum metaphosphate supported nickel-palladium catalyst involves using nickel acetylacetone as the nickel source and palladium acetylacetone as the palladium source. A certain amount of TFMSA and Al(PO3)3 support are dissolved in acetone, stirred and heated overnight, the solvent is removed and dried, and then calcined in a tube furnace under an inert atmosphere. The catalyst is then reduced with hydrogen to obtain a NiPd-TFMSA / Al(PO3)3 catalyst. The specific steps are as follows:

[0032] Step 1: Add 1g of support Al(PO3)3, 4-trifluoromethylsalicylic acid TFMSA, nickel source, and palladium source to 20mL of acetone. Stir at 500rpm for 16h at room temperature. Remove the solvent acetone by rotary evaporation and dry in a vacuum drying oven at 70℃ for 2h. Grind the obtained solid into a solid powder with a particle size of 60-200 mesh using a mortar. The mass of TFMSA is 0%, 10%, 15%, and 20% of the support mass, the mass of nickel is 6%, 7%, 8%, and 10% of the support mass, and the mass of palladium is 6%, 5%, 4%, and 2% of the support mass.

[0033] Step 2: The solid powder obtained in the previous step is heated to a specified temperature in a tube furnace under N2 atmosphere at a heating rate of 5℃ / min, and calcined and held at that temperature for 2 hours to obtain solid powder; the specified temperatures are 400℃, 500℃, 600℃ and 700℃ respectively.

[0034] Step 3: The solid powder obtained in Step 2 is heated to the specified temperature at a heating rate of 5℃ / min under H2 atmosphere and reduced for 2h. The H2 flow rate is 10-100mL / min. The resulting black solid powder is the organic acid modified aluminum metaphosphate supported nickel palladium catalyst, denoted as NiPd-TFMSA / Al(PO3)3. The specified temperatures are 30℃, 400℃, 500℃ and 600℃.

[0035] The application of organic acid-modified aluminum metaphosphate supported nickel-palladium catalyst in the catalytic hydrocracking of lignite-related model compounds: 0.2 g benzylphenyl ether, 0.05 g NiPd-TFMSA / Al(PO3)3 and 15 g n-hexane were added to a magnetically stirred high-pressure reactor. After purging the air three times with nitrogen, hydrogen gas was introduced at 1 MPa, and the reaction was carried out at 180 °C for 2 h. After the reaction was completed, the reactor was cooled to room temperature and the pressure was released. The supernatant was then removed, and the composition of the catalytic hydrocracking products was qualitatively and quantitatively analyzed by GC-MS and GC.

[0036] The characterization results of the catalyst are as follows: Figure 1 and Figure 2 As shown.

[0037] Figure 1 The images show the XRD patterns of the support and different catalysts used in this application. Figure 1 The results show that no obvious Ni and Pd diffraction peaks were observed in any of the catalysts, indicating that the active components Ni and Pd are uniformly dispersed on the support surface; all the peaks in the figure belong to the support Al(PO3)3, indicating that the structure of the support was completely preserved during the catalyst preparation process.

[0038] Figure 2 The images show SEM, HRTEM, and SEM-EDS images of the NiPd-TFMSA / Al(PO3)3 catalyst of this application. The images show that the active components Ni and Pd are well distributed on the support surface, with a particle size distribution between 5-30 nm.

[0039] Example 2:

[0040] The effect of NiPd-TFMSA / Al(PO3)3 catalysts calcined at different temperatures on the catalytic hydrogenation of lignite-related model compounds was investigated. Nickel acetylacetone was used as the nickel source, and palladium acetylacetone was used as the palladium source. A certain amount of TFMSA and Al(PO3)3 support were dissolved in acetone, stirred and heated overnight, and after solvent removal and drying, calcined in an inert atmosphere tube furnace and reduced with hydrogen to obtain the NiPd-TFMSA / Al(PO3)3 catalyst. The specific steps are as follows:

[0041] Step 1: Add 1g of carrier Al(PO3)3, 4-trifluoromethylsalicylic acid TFMSA, nickel source and palladium source to 20mL of acetone, stir at 500rpm for 16h at room temperature, remove the solvent acetone by rotary evaporation, and dry in a vacuum drying oven at 70℃ for 2h. Grind the obtained solid into a solid powder with a particle size of 60-200 mesh using a mortar and pestle; the mass of nickel is 10% of the carrier mass, the mass of palladium is 2% of the carrier mass, and the mass of 4-trifluoromethylsalicylic acid TFMSA is 20% of the carrier mass.

[0042] Step 2: The solid powder obtained in the previous step is heated to a specified temperature in a tube furnace under N2 atmosphere at a heating rate of 5℃ / min, and calcined and held at that temperature for 2 hours to obtain solid powder; the specified temperatures are 400℃, 500℃, 600℃ and 700℃ respectively.

[0043] Step 3: The solid powder obtained in step 2 is heated to 500℃ in H2 atmosphere at a heating rate of 5℃ / min and reduced for 2h. The H2 flow rate is 10-100mL / min. The resulting black solid powder is the organic acid modified aluminum metaphosphate supported nickel palladium catalyst, denoted as NiPd-TFMSA / Al(PO3)3.

[0044] The effect of NiPd-TFMSA / Al(PO3)3 catalyst on the catalytic hydrogenation of lignite-related model compounds.

[0045] 0.2 g of benzylphenyl ether, 0.05 g of NiPd-TFMSA / Al(PO3)3, and 15 g of n-hexane were added to a magnetically stirred high-pressure reactor. After purging the air three times with nitrogen, hydrogen gas was introduced at 1 MPa, and the reaction was carried out at 180 °C for 2 h. After the reaction, the reactor was cooled to room temperature, the pressure was released, and the supernatant was removed. The composition of the catalytic hydrocracking products was qualitatively and quantitatively analyzed by GC-MS and GC. The results showed that the NiPd-TFMSA / Al(PO3)3 catalyst had a good hydrocracking effect on benzylphenyl ether, and the effect was optimal when the support calcination temperature was 600 °C. Figure 3 As shown.

[0046] Example 3:

[0047] The effect of NiPd-TFMSA / Al(PO3)3 catalysts with different nickel-palladium ratios on the catalytic hydrogenation of lignite-related model compounds was investigated. Nickel acetylacetone was used as the nickel source, and palladium acetylacetone was used as the palladium source. A certain amount of TFMSA and Al(PO3)3 support were dissolved in acetone, stirred and heated overnight, and after solvent removal and drying, calcined in an inert atmosphere tube furnace and reduced with hydrogen to obtain the NiPd-TFMSA / Al(PO3)3 catalyst. The specific steps are as follows:

[0048] Step 1: Add 1g of carrier Al(PO3)3, 4-trifluoromethylsalicylic acid TFMSA, nickel source, and palladium source to 20mL of acetone. Stir at 500rpm for 16h at room temperature. Remove the solvent acetone by rotary evaporation and dry the resulting suspension at 70℃ for 2h in a vacuum drying oven. Grind the resulting solid into a solid powder with a particle size of 60-200 mesh using a mortar. The mass of nickel is 6%, 7%, 8%, and 10% of the carrier mass, and the mass of palladium is 6%, 5%, 4%, and 2% of the carrier mass. The mass of 4-trifluoromethylsalicylic acid TFMSA is 20% of the carrier mass.

[0049] Step 2: The solid powder obtained in the previous step is heated to 600°C in a tube furnace under N2 atmosphere at a heating rate of 5°C / min, and calcined and held at that temperature for 2 hours to obtain solid powder.

[0050] Step 3: The solid powder obtained in step 2 is heated to 500℃ in H2 atmosphere at a heating rate of 5℃ / min and reduced for 2h. The H2 flow rate is 10-100mL / min. The resulting black solid powder is the organic acid modified aluminum metaphosphate supported nickel palladium catalyst, denoted as NiPd-TFMSA / Al(PO3)3.

[0051] The effect of NiPd-TFMSA / Al(PO3)3 catalyst on the catalytic hydrogenation of lignite-related model compounds.

[0052] 0.2 g benzylphenyl ether, 0.05 g NiPd-TFMSA / Al(PO3)3 and 15 g n-hexane were added to a magnetically stirred high-pressure reactor. After purging the air three times with nitrogen, hydrogen gas was introduced at 1 MPa and the reaction was carried out at 180 °C for 2 h. After the reaction was completed, the reactor was cooled to room temperature and the pressure was released. The supernatant was then removed and the composition of the catalytic hydrocracking products was qualitatively and quantitatively analyzed by GC-MS and GC.

[0053] The results showed that the NiPd-TFMSA / Al(PO3)3 catalyst had the best hydrocracking effect on benzylphenyl ether, and the best effect was achieved when the mass of nickel was 7% of the support mass and the mass of palladium was 5% of the support mass. Figure 4 As shown.

[0054] Example 4:

[0055] The effect of NiPd / Al(PO3)3 catalyst without TFMSA on the catalytic hydrogenation of lignite-related model compounds was investigated. Nickel acetylacetone was used as the nickel source, palladium acetylacetone as the palladium source, and Al(PO3)3 as the support. The catalyst was dissolved in acetone, stirred and heated overnight, and after solvent removal and drying, calcined in an inert atmosphere tube furnace and reduced with hydrogen to obtain the NiPd-TFMSA / Al(PO3)3 catalyst. The specific steps are as follows:

[0056] Step 1: Add 1g of Al(PO3)3, nickel source, and palladium source to 20mL of acetone and stir at 500rpm for 16h at room temperature. Remove the solvent acetone from the resulting suspension by rotary evaporation and dry it in a vacuum drying oven at 70℃ for 2h. Grind the resulting solid into a solid powder with a particle size of 60-200 mesh using a mortar and pestle. The mass of nickel is 7% of the carrier mass, and the mass of palladium is 5%.

[0057] Step 2: The solid powder obtained in the previous step is heated to 600°C in a tube furnace under N2 atmosphere at a heating rate of 5°C / min, and calcined and held at that temperature for 2 hours to obtain solid powder.

[0058] Step 3: The solid powder obtained in step 2 is heated to 500℃ in H2 atmosphere at a heating rate of 5℃ / min and reduced for 2h. The H2 flow rate is 10-100mL / min. The resulting black solid powder is the aluminum metaphosphate supported nickel palladium catalyst, denoted as NiPd / Al(PO3)3.

[0059] The effect of NiPd / Al(PO3)3 catalyst without TFMSA on the catalytic hydrogenation of lignite-related model compounds.

[0060] 0.2 g benzylphenyl ether, 0.05 g NiPd / Al(PO3)3 and 15 g n-hexane were added to a magnetically stirred high-pressure reactor. After the air was replaced with nitrogen three times, hydrogen gas was introduced at 1 MPa and the reaction was carried out at 180 °C for 2 h. After the reaction was completed, the reactor was cooled to room temperature and the pressure was released. The supernatant was then removed and the composition of the catalytic hydrocracking products was qualitatively and quantitatively analyzed by GC-MS and GC.

[0061] The results showed that the conversion rate of benzylphenyl ether hydrocracking by the NiPd / Al(PO3)3 catalyst without TFMSA was much lower than that when the TFMSA addition was 15% and 20% of the support mass. Figure 5 As shown.

[0062] The embodiments proposed in this invention are preferred embodiments, but are not limited to the content described above. Those skilled in the art can easily replicate the above embodiments and further extend and modify them, but as long as they do not depart from the spirit of this invention, they are all within the protection scope of this invention.

Claims

1. A method for preparing an organic acid-modified aluminum metaphosphate supported nickel-palladium catalyst, characterized by, The specific steps are as follows: First step: according to the mass fraction of the carrier Al (PO3) 3: 4-trifluoromethyl salicylic acid TFMSA: nickel source: palladium source = 1 part: 0~20 parts: 6~10 parts: 2~6 parts, the carrier Al (PO3) 3, 4-trifluoromethyl salicylic acid TFMSA, nickel source and palladium source are added into acetone, stirred at room temperature at a speed of 500 rpm for 4-24 h, the obtained suspension is dried in a vacuum drying oven at 70℃ for 2-6 h after removing the solvent acetone by rotary evaporation, and the obtained solid is ground into a solid powder with a particle size of 60-200 mesh; the nickel source is nickel acetylacetone, the palladium source is palladium acetylacetone, and the mass ratio of the carrier Al (PO3) 3 to acetone is 1 g: 20 mL; Second step: the solid powder obtained in the above step is calcined in a tube furnace under an inert atmosphere at a temperature rising rate of 2-10℃ / min to a specified temperature, and is kept at the specified temperature for 1-4 h to obtain a solid powder; Third step: the solid powder obtained in the second step is reduced in a H2 atmosphere at a temperature rising rate of 2-10℃ / min to a specified temperature, and is kept at the specified temperature for 1-4 h, the H2 flow rate is 10-100 mL / min, and a black solid powder is obtained, which is an organic acid modified aluminum metaphosphate supported nickel-palladium catalyst, denoted as NiPd-TFMSA / Al (PO3) 3.

2. The process for the preparation of an organo acid modified aluminium metaphosphate supported nickel palladium catalyst as claimed in claim 1, wherein: The inert atmosphere in the second step is N2, and the specified temperature is 400~700℃.

3. The method for preparing an organic acid-modified aluminum metaphosphate supported nickel-palladium catalyst according to claim 1, characterized in that: The specified temperature in the third step is 300~600℃.

4. The application of the organic acid modified aluminum metaphosphate supported nickel-palladium catalyst prepared by the preparation method of any one of claims 1-3 in the catalytic hydrocracking of lignite and its model compounds.

5. Use according to claim 4, characterized in that: According to the mass fraction, 1-10 parts of a reaction substrate, 0.1-0.5 parts of NiPd-TFMSA / Al (PO3) 3 and 50-200 parts of a solvent are added into a magnetic stirring high-pressure reaction kettle, the air is replaced with nitrogen for 3 times, 0.5-2 MPa of hydrogen is filled, and the reaction is carried out at 140-200℃ for 1-4 h. After the reaction is completed, the reaction kettle is cooled to room temperature and the pressure is released, and the upper liquid is taken out and analyzed by GC-MS and GC.

6. Use according to claim 5, characterized in that: The reaction substrate is a compound containing a C-O bridge, specifically one or more of lignite and diphenyl ether, benzyl phenyl ether, dibenzyl ether, phenoxy ethylbenzene, 2-phenoxy naphthalene, 2,2'-dinaphthyl ether and 2-naphthyl benzyl ether.

7. Use according to claim 5, characterized in that: The solvent is one or more of methanol, ethanol, isopropanol, n-hexane and 1,4-dioxane.

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