Method for preparing fatty alcohol through catalytic oxidation of petroleum hydrocarbon

Abstract

The invention discloses a method for preparing fatty alcohol by catalytic oxidation of petroleum hydrocarbon, which comprises the following steps: dissolving petroleum hydrocarbon in an organic solvent, and reacting in the presence of a transition metal complex catalyst and an oxidant to mainly obtain the fatty alcohol. The method provided by the invention uses a clean oxidant, has high selectivity, avoids use of an expensive metal catalyst, has mild reaction conditions, simple operation and high atom economy, can be used in industrial production of fatty alcohol prepared from petroleum hydrocarbon, and can produce high-added-value organic chemicals through subsequent processing.

Description

Technical Field

[0001] The invention relates to a conversion reaction of hydrocarbons and a method for preparing fatty alcohols, and in particular to a method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons. Background Art

[0002] Higher fatty alcohols are an important class of organic chemical products. They can be used as raw materials for high value-added organic chemicals such as surfactants, lubricants, thickeners, stabilizers, and are widely used in industrial production such as petrochemicals. Fatty alcohols can be synthesized by methods such as oil sodium reduction, fatty acid hydrogenation, and fatty acid methyl ester hydrogenation. However, the current methods either use expensive reagents, high energy consumption, low yield, and produce highly toxic substances during the process; or require harsh reaction conditions such as high temperature and high pressure. Therefore, the present invention prepares a transition metal catalyst with good selectivity and is used to catalyze the oxidation of petroleum hydrocarbons to prepare fatty alcohols.

[0003] Petroleum hydrocarbons are the main products of alkanes from petroleum cracking and are abundant in sources. 3 The inert nature of the )–H bond (BDE>380kJ / mol) makes it thermodynamically and kinetically less reactive, and is generally more difficult to oxidize than alkenes, alkynes, and alcohols. Under the same reaction conditions, alcohols are generally more reactive than alkane substrates, which will inevitably lead to excessive oxidation of alkanes to ketones, reducing their reaction selectivity. Some noble metal complexes such as Ir and Rh have been prepared to catalyze the oxidation of normal alkanes, with a selectivity of only 26% for fatty alcohols. Therefore, the direct oxidation of straight-chain alkanes is very challenging, and the design and preparation of inexpensive catalysts for activating oxidants is particularly necessary. Summary of the invention

[0004] The present invention aims to overcome the shortcomings of low conversion rate and selectivity in the existing method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons, and provides a method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons. The method has high selectivity and conversion rate for fatty alcohols, mild reaction conditions, easy operation, and the metal complex catalyst used is cheap and easy to operate.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions: A method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons comprises the following steps: A petroleum hydrocarbon solution, a transition metal complex catalyst and an oxidant are reacted at 25 to 100° C. for 0.5 to 6 hours to obtain a fatty alcohol.

[0006] Furthermore, petroleum hydrocarbons are normal alkanes, and their molecular formula is nC m H 2m+2 , 8 ≤ m ≤ 20. Furthermore, the amount of the transition metal complex catalyst used is 1 to 5% of the amount of petroleum hydrocarbon.

[0007] Furthermore, the transition metal complex catalyst is Mn(dtbpy)2(OTf)2, Fe(dtbpy)2(OTf)2, Cu(dtbpy)2(OTf)2, Co(dtbpy)2(OTf)2, wherein dtbpy represents 4,4'-di-tert-butyl-2,2'-bipyridine, and OTf represents trifluoromethanesulfonic acid.

[0008] Further, the transition metal complex catalyst Mn(dtbpy)2(OTf)2 is prepared by the following process: Manganese trifluoromethanesulfonate and 4,4'-di-tert-butyl-2,2'-bipyridine were added to acetonitrile, and the mixture was stirred at 60°C for 12 h under nitrogen protection to obtain Mn(dtbpy)2(OTf)2.

[0009] Furthermore, the molar ratio of manganese trifluoromethanesulfonate to 4,4'-di-tert-butyl-2,2'-bipyridine is 1:2.

[0010] Furthermore, the amount of the oxidant used is 5 to 30 times the amount of the petroleum hydrocarbon substance.

[0011] Furthermore, the oxidant is any one of hydrogen peroxide, tert-butyl hydroperoxide and oxygen.

[0012] Furthermore, the solvent in the petroleum hydrocarbon solution is any one of acetonitrile, acetic acid, 1,2-dichloroethane, tetrahydrofuran, methanol and ethanol.

[0013] Furthermore, the hydroxyl groups of the fatty alcohol are at the 2, 3 and 4 positions.

[0014] Compared with the prior art, the present invention has the following beneficial effects: In the present invention, the transition metal complex catalyst and the oxidant form a high-valent metal oxo intermediate, and then the metal oxo intermediate attacks the petroleum hydrocarbon, promoting the activation of the internal carbon and the formation of alcohol, thereby realizing the generation of fatty alcohol. The preparation method of the present invention uses a clean oxidant, has high selectivity, avoids the use of expensive metal complex catalysts, has mild reaction conditions, is easy to operate, and has high atom economy. The method can be used in the industrial production of preparing fatty alcohol from petroleum hydrocarbon, and can be used as a raw material in subsequent processing to produce high-value-added organic chemicals such as surfactants, lubricants, and thickeners. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a gas chromatogram of the catalytic oxidation reaction of n-octane in Example 1; Figure 2Schematic diagram of the single crystal structure of the manganese metal complex catalyst of Example 1. DETAILED DESCRIPTION

[0016] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly and comprehensively understood.

[0017] A method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons of the present invention comprises the following steps: A metal complex catalyst and an oxidant are used to catalyze the reaction of petroleum hydrocarbons to generate fatty alcohols, wherein a transition metal complex catalyst and a clean oxidant are used.

[0018] The specific steps are: dissolving petroleum hydrocarbon in an organic solvent, then adding a transition metal complex catalyst and an oxidant, and carrying out a catalytic reaction at 25 to 100° C. for 0.5 to 6 hours to obtain fatty alcohol.

[0019] More preferably, the reaction time is 1 to 5 hours.

[0020] The amount of the transition metal complex catalyst used is 1 to 5% of the amount of petroleum hydrocarbon.

[0021] The amount of oxidant used is 5 to 30 times the amount of petroleum hydrocarbon.

[0022] The transition metal complex catalyst is Mn(dtbpy)2(OTf)2, Fe(dtbpy)2(OTf)2, Cu(dtbpy)2(OTf)2, Co(dtbpy)2(OTf)2, wherein dtbpy represents 4,4'-di-tert-butyl-2,2'-bipyridine, and OTf represents trifluoromethanesulfonic acid.

[0023] The oxidizing agent is any one of hydrogen peroxide, tert-butyl hydroperoxide and oxygen.

[0024] Petroleum hydrocarbons are normal alkanes, and the molecular formula of petroleum hydrocarbons is nC m H 2m+2 (8 ≤ m ≤ 20). More preferably, the petroleum hydrocarbon is n-octane, and the fatty alcohol is 2-octanol, 3-octanol or 4-octanol.

[0025] The organic solvent is any one of acetonitrile, acetic acid, 1,2-dichloroethane, tetrahydrofuran, methanol and ethanol.

[0026] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the materials and reagents used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0027] In the following examples, the calculation method of the product is: Selectivity is expressed as the fraction of the moles of each product to the total moles of all products.

[0028] Examples 1-4 use catalysts of different metal complexes.

[0029] Taking n-octane as raw material, the catalytic system is composed of different metal complex catalysts and oxidants. The specific reaction formula is as follows:

[0030] Example 1 Preparation of manganese metal complex catalyst:

[0031] Manganese trifluoromethanesulfonate (0.05 mmol, 0.0175 g) and 4,4'-di-tert-butyl-2,2'-bipyridine (0.1 mmol, 0.0268 g) were added to acetonitrile (4 mL) in sequence in the reaction tube. The air in the reaction tube was evacuated by a vacuum pump and nitrogen was introduced. The reaction was stirred at 60 °C for 12 h and the reaction was stopped. The product was filtered and concentrated, and a single crystal was prepared by liquid phase diffusion method (dichloromethane / n-hexane) to obtain a manganese metal complex catalyst Mn(dtbpy)2(OTf)2, where dtbpy represents 4,4'-di-tert-butyl-2,2'-bipyridine. The obtained product was characterized by a Bruker D8 Venture single crystal X-ray diffractometer, see Figure 2 , the characterization data are as follows: Bond precision: CC = 0.0119 A; Wavelength=0.71073; Cell: a=10.8249(8), b=20.7051(15), c=18.3799(13); alpha=90, beta=90.305(3), gamma=90; Temperature: 170 K; Volume: 4119.4(5); Space group: P121 / n1; Hall group: -P 2yn; Moiety formul: C38 H 48 F6Mn N4O6S2; Sum formula: C 38 H 48 F6Mn N4O6S2; Mr: 889.86; Dx,g cm -3 : 1.435; Z: 4; Mu (mm -1 ): 0.498; F(000):1852.0; h,k,lmax:13,25,23 ; Nref:8475; Tmin, Tmax: 0.587, 0.745; Correction method= #Reported T Limits: Tmin=0.587, Tmax=0.745; AbsCorr = MULTI-SCAN; Data completeness= 0.997, Theta(max)= 26.439; R(reflections)=0.1277(7255), wR2(reflections)=0.3019(8475); S = 1.151, Npar = 526.

[0032] Preparation of fatty alcohols: n-octane (1 mmol, 0.16 mL) was dissolved in acetic acid (2 mL), and a manganese metal complex catalyst (0.05 mmol, 0.0444 g) and an aqueous hydrogen peroxide solution (10 mmol of hydrogen peroxide, 0.3 mL of an aqueous hydrogen peroxide solution) were added. The reaction was catalytically reacted at 60 °C for 1 h and then stopped. The reaction solution was then taken out and filtered through a silica gel plug and fixed to volume with a 10 mL volumetric flask. 1 μL of the solution was injected into an Agilent 7890B gas chromatograph for product analysis and quantification to obtain fatty alcohols.

[0033] The chromatograph was equipped with a flame ionization detector (FID) and the temperature was set to 260 °C. The products were separated using an HP-INNOWax column and the injector temperature was set to 240 °C. The heating program was as follows: the initial temperature was 50 °C and maintained for 2 min, then heated to 100 °C at a rate of 5 °C / min and maintained for 8 min, and finally heated to 230 °C at a rate of 15 °C / min and maintained for 2 min. The split ratio was 1:30; the injection volume was 1 μL. The gas chromatogram is shown in Figure 1. Figure 1 The retention times of the raw materials and different products are shown in Table 1.

[0034] Table 1 Retention time of raw materials and different products

[0035] Example 2 Iron trifluoromethanesulfonate (0.05 mmol, 0.0177 g) and 4,4'-di-tert-butyl-2,2'-bipyridine (0.1 mmol, 0.0268 g) were added to a reaction tube in acetonitrile (4 mL) in sequence. The air in the reaction tube was evacuated by a vacuum pump and nitrogen was introduced. The reaction was stirred at 60 °C for 12 h to obtain an iron metal complex catalyst.

[0036] Preparation of fatty alcohols: n-octane (1 mmol, 0.16 mL) was dissolved in acetic acid (2 mL), and an iron metal complex catalyst (0.05 mmol, 0.0445 g) and an aqueous hydrogen peroxide solution (10 mmol, 0.3 mL) were added. The reaction was catalytically reacted at 60 °C for 1 h and then stopped. The reaction solution was then taken out and filtered through a silica gel plug and fixed to volume with a 10 mL volumetric flask. 1 μL of the solution was injected into an Agilent 7890B gas chromatograph for product analysis and quantification to obtain fatty alcohols.

[0037] Example 3 Copper trifluoromethanesulfonate (0.05 mmol, 0.0180 g) and 4,4'-di-tert-butyl-2,2'-bipyridine (0.1 mmol, 0.0268 g) were added to a reaction tube in acetonitrile (4 mL) in sequence. The air in the reaction tube was evacuated by a vacuum pump and nitrogen was introduced. The reaction was stirred at 60 °C for 12 h to obtain a copper metal complex catalyst.

[0038] Preparation of fatty alcohols: n-octane (1 mmol, 0.16 mL) was dissolved in acetic acid (2 mL), and a copper metal complex catalyst (0.05 mmol, 0.0448 g) and an aqueous hydrogen peroxide solution (10 mmol, 0.3 mL) were added. The reaction was catalytically reacted at 60 °C for 1 h and then stopped. The reaction solution was then taken out and filtered through a silica gel plug and fixed to volume with a 10 mL volumetric flask. 1 μL of the solution was injected into an Agilent 7890B gas chromatograph for product analysis and quantification to obtain fatty alcohols.

[0039] Example 4 Cobalt trifluoromethanesulfonate (0.05 mmol, 0.0178 g) and 4,4'-di-tert-butyl-2,2'-bipyridine (0.1 mmol, 0.0268 g) were added to a reaction tube in acetonitrile (4 mL) in sequence. The air in the reaction tube was evacuated by a vacuum pump and nitrogen was introduced. The reaction was stirred at 60 °C for 12 h to obtain a cobalt metal complex catalyst.

[0040] Preparation of fatty alcohols: n-octane (1 mmol, 0.16 mL) was dissolved in acetic acid (2 mL), and a cobalt metal complex catalyst (0.05 mmol, 0.0446 g) and an aqueous hydrogen peroxide solution (10 mmol, 0.3 mL) were added. The reaction was catalytically reacted at 60 °C for 1 h and then stopped. The reaction solution was then taken out and filtered through a silica gel plug and fixed to volume with a 10 mL volumetric flask. 1 μL of the solution was injected into an Agilent 7890B gas chromatograph for product analysis and quantification to obtain fatty alcohols.

[0041] The yields and selectivities of different metal complex catalysts and unconverted alkane substrates and fatty alcohols used in the reaction are shown in Table 2: Table 2 Yield and selectivity of different metal complex catalysts and unconverted alkane substrates and fatty alcohols

[0042] By analyzing Table 2, it was found that among the four different metal complex catalysts, the manganese metal complex catalyst had the highest yield (16.87%) and the highest selectivity for fatty alcohol products (74.45%). 83.13% of the alkane substrate was not converted, and the remaining substrate could be separated and the converted substrate could be recovered for the next round of catalytic oxidation cycle.

[0043] Examples 5-8 are reactions using different solvents.

[0044] Taking n-octane as raw material, a catalytic system is formed by a manganese metal complex catalyst and an oxidant, and the reaction is carried out in different solvents. The specific reaction formula is as follows:

[0045] Example 5 The preparation steps of the manganese metal complex catalyst are the same as those in Example 1; The preparation of fatty alcohol is the same as in Example 1, except that the solvent acetic acid is replaced by acetonitrile.

[0046] Example 6 The preparation steps of the manganese metal complex catalyst are the same as those in Example 1; The preparation of fatty alcohol is the same as in Example 1, except that the solvent acetic acid is replaced by methanol.

[0047] Example 7 The preparation steps of the manganese metal complex catalyst are the same as those in Example 1; The preparation of fatty alcohol is the same as in Example 1, except that the solvent acetic acid is replaced by ethanol.

[0048] Example 8 The preparation steps of the manganese metal complex catalyst are the same as those in Example 1; The preparation of fatty alcohol is the same as in Example 1, except that the solvent acetic acid is replaced by a mixture of acetic acid and acetonitrile in a volume ratio of 1:1.

[0049] The yields and selectivities of different solvents used in the reaction and the unconverted alkane substrates and fatty alcohols are shown in Table 3.

[0050] Table 3 Yield and selectivity results of different solvents and unconverted alkane substrates and fatty alcohols

[0051] By analyzing Table 2 and Table 3, it was found that when acetic acid was used as the solvent, the yield of n-octane was the highest (16.87%) and had good selectivity for fatty alcohol products (74.45%).

[0052] Examples 9-13 are examples of reactions with different catalyst concentrations.

[0053] Taking n-octane as raw material, a catalytic system is formed by a manganese metal complex catalyst and an oxidant, and the reaction is carried out at different catalyst concentrations. The specific reaction formula is as follows:

[0054] Example 9 Catalyst preparation: Same as in Example, except that the amount of manganese trifluoromethanesulfonate used is 0.01 mmol, and the amount of 4,4'-di-tert-butyl-2,2'-bipyridine used is 0.02 mmol.

[0055] Preparation of fatty alcohol: Same as Example 1.

[0056] Example 10 Catalyst preparation: Same as in Example, except that the amount of manganese trifluoromethanesulfonate used is 0.02 mmol, and the amount of 4,4'-di-tert-butyl-2,2'-bipyridine used is 0.04 mmol.

[0057] Preparation of fatty alcohol: Same as Example 1.

[0058] Embodiment 11 Catalyst preparation: Same as in Example 1, except that the amount of manganese trifluoromethanesulfonate used was 0.03 mmol, and the amount of 4,4'-di-tert-butyl-2,2'-bipyridine used was 0.06 mmol.

[0059] Preparation of fatty alcohol: Same as Example 1.

[0060] Example 12 Catalyst preparation: Same as in Example, except that the amount of manganese trifluoromethanesulfonate used is 0.04 mmol, and the amount of 4,4'-di-tert-butyl-2,2'-bipyridine used is 0.08 mmol.

[0061] Preparation of fatty alcohol: Same as Example 1.

[0062] Example 13 Catalyst preparation: Same as in Example 1, except that the amount of manganese trifluoromethanesulfonate used was 0.05 mmol, and the amount of 4,4'-di-tert-butyl-2,2'-bipyridine used was 0.1 mmol.

[0063] Preparation of fatty alcohol: Same as Example 1.

[0064] The yields and selectivities of the different concentrations of manganese metal complex catalysts and the unconverted alkane substrates and fatty alcohols used in the reaction are shown in Table 4.

[0065] Table 4 Yield and selectivity results of different concentrations of manganese metal complex catalysts and unconverted alkane substrates and fatty alcohols

[0066] By analyzing Tables 2 and 4, it is found that with the gradual increase in the concentration of the manganese metal complex catalyst, the yield of n-octane basically shows an upward trend, and it is found that the different catalyst concentrations have little effect on the selectivity of fatty alcohols and fatty ketones, and remain stable. When the catalyst concentration is 5 mol% and 10 mol%, the n-octane yield is basically similar. Therefore, out of consideration for green chemistry, a catalyst concentration of 5 mol% is selected for catalytic oxidation reaction.

[0067] Examples 14-17 are different reaction temperatures.

[0068] Taking n-octane as raw material, a catalytic system is formed by a manganese metal complex catalyst and an oxidant, and the reaction is carried out at different temperatures. The specific reaction formula is as follows:

[0069] Embodiment 14 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the reaction temperature is room temperature (25°C).

[0070] Embodiment 15 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the reaction temperature is 40°C.

[0071] Example 16 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the reaction temperature is 80°C.

[0072] Embodiment 17 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the reaction temperature is 100°C.

[0073] The yields and selectivities of the different reaction temperatures and the unconverted alkane substrates and fatty alcohols are shown in Table 5.

[0074] Table 5 Yield and selectivity results of different temperatures and unconverted alkane substrates and fatty alcohols

[0075] By analyzing Table 2 and Table 5, it is found that as the temperature gradually increases, when it reaches 60 °C, the yield of n-octane is the highest (16.87%), and the selectivity for fatty alcohol is the best (74.45%). When the temperature continues to rise, the yield of n-octane decreases instead of increasing, and as the temperature increases, the occurrence of over-oxidation is accelerated, causing some fatty alcohols to be oxidized to fatty ketones at high temperatures, resulting in a decrease in the selectivity of fatty alcohols.

[0076] Examples 17-20 are of different reaction times.

[0077] Taking n-octane as raw material, a catalytic system is formed by a manganese metal complex catalyst and an oxidant, and the reaction is carried out at different reaction times. The specific reaction formula is as follows:

[0078] Embodiment 17 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the reaction time is 0.5 h.

[0079] Embodiment 18 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the reaction time is 2 h.

[0080] Embodiment 19 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the reaction time is 3 h.

[0081] Embodiment 20 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the reaction time is 6 h.

[0082] The yields and selectivities of the products obtained at different reaction times are shown in Table 6.

[0083] Table 6 Yield and selectivity results of different reaction times and unconverted alkane substrates and fatty alcohols

[0084] By analyzing Table 2 and Table 6, it was found that with the gradual increase of time, the yield of n-octane did not change much, reaching the highest at 1 h (16.87%), and the selectivity for fatty alcohol products was the highest (74.45%).

[0085] Examples 21-24 are reactions with different amounts of oxidant added.

[0086] Taking n-octane as raw material, a catalytic system is formed by a manganese metal complex catalyst and an oxidant, and the reaction is carried out under different oxidant addition amounts. The specific reaction formula is as follows:

[0087] Embodiment 21 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the amount of hydrogen peroxide solution used is 5 mmol.

[0088] Embodiment 22 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the amount of hydrogen peroxide solution used is 15 mmol.

[0089] Embodiment 23 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the amount of hydrogen peroxide solution used is 20 mmol.

[0090] Embodiment 24 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the amount of hydrogen peroxide solution used is 25 mmol.

[0091] Embodiment 25 Catalyst preparation: same as in Example 1; Preparation of fatty alcohol: Same as Example 1, except that the amount of hydrogen peroxide solution used is 30 mmol.

[0092] The yields and selectivities of different oxidant additions and unconverted alkane substrates and fatty alcohols are shown in Table 7.

[0093] Table 7 Yield and selectivity results of different oxidant additions and unconverted alkane substrates and fatty alcohols

[0094] By analyzing Table 2 and Table 7, it is found that with the increase of the amount of oxidant, when the amount of oxidant is 15 eq, the n-octane yield reaches the highest (17.72%), and with the continued increase of the amount of oxidant, the n-octane yield gradually decreases, and the reaction is inhibited; when the amount of oxidant is 10 eq, the selectivity of fatty alcohol is the highest (74.45%), of which 83.13% of the alkane substrate is not converted. The remaining substrate can be separated, and the recovered unconverted substrate is used for the next round of catalytic oxidation cycle.

[0095] In the prior art, the efficiency of the catalytic oxidation of petroleum hydrocarbons to prepare fatty alcohols is generally low, and over-oxidation products such as fatty ketones are easily generated, resulting in low selectivity and low yield of the target product fatty alcohol. For example, Dunesha Naicker (J Chem Res., 2020, 1-9) et al. provided a method for the catalytic oxidation of n-octane by Ir and Rh complexes, achieving higher selectivity for ketones and acids, with a maximum selectivity of only 26% for alcohols; Siyabonga G. Mncube (Inorg Chim Acta., 2017, 463, 112-117) et al. synthesized N-heterocyclic carbene ligands containing mediating ions by reacting nickelocene with the corresponding triazolium salts, and used hydrogen peroxide as an oxidant to obtain the corresponding ketone products and a small amount of alcohol products (28%); Ebrahim Kadwa (Mol. Catal., 2017, 482, 100107) et al. studied a series of Salen-type iron complexes for the catalytic oxidation of n-octane, using hydrogen peroxide and tert-butyl hydroperoxide as oxidants, resulting in ketones dominating the oxidation products, even with a selectivity of up to 100%, and the selectivity of alcohol products was only 36% at most. Most expensive metal compounds used as catalysts not only cause serious environmental pollution, but also lead to the massive production of excessive oxidation products such as fatty ketones. The preparation method of the present invention avoids the use of expensive metal complexes and does not use strong oxidants that are sensitive to water and air. The reaction conditions are mild, the selectivity is high, the operation is easy, the price is low, and the atom economy is high.

[0096] The organic solvent in the present invention may also be 1,2-dichloroethane or tetrahydrofuran.

[0097] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. However, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0098] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

Claims

1. A method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons, characterized in that: The following steps are involved: The petroleum hydrocarbon solution, transition metal complex catalyst and oxidant are reacted at 25-100°C for 0.5-6h to obtain fatty alcohol.

2. The method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons according to claim 1, characterized in that: Petroleum hydrocarbons are normal alkanes, and their molecular formula is nC m H 2m+2 , 8 ≤ m ≤ 20.

3. The method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons according to claim 1, characterized in that: The amount of the transition metal complex catalyst used is 1 to 5% of the amount of petroleum hydrocarbon.

4. The method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons according to claim 1, characterized in that: The transition metal complex catalyst is Mn(dtbpy)2(OTf)2, Fe(dtbpy)2(OTf)2, Cu(dtbpy)2(OTf)2, Co(dtbpy)2(OTf)2, wherein dtbpy represents 4,4'-di-tert-butyl-2,2'-bipyridine, and OTf represents trifluoromethanesulfonic acid.

5. The method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons according to claim 4, characterized in that: The transition metal complex catalyst Mn(dtbpy)2(OTf)2 was prepared by the following process: Manganese trifluoromethanesulfonate and 4,4'-di-tert-butyl-2,2'-bipyridine were added to acetonitrile and stirred at 60 °C for 12 h under nitrogen protection to obtain Mn(dtbpy)2(OTf)2.

6. The method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons according to claim 5, characterized in that: The molar ratio of manganese trifluoromethanesulfonate to 4,4'-di-tert-butyl-2,2'-bipyridine is 1:

2.

7. The method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons according to claim 1, characterized in that: The amount of oxidant used is 5 to 30 times the amount of petroleum hydrocarbon material.

8. The method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons according to claim 1, characterized in that: The oxidizing agent is any one of hydrogen peroxide, tert-butyl hydroperoxide and oxygen.

9. The method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons according to claim 1, characterized in that: The solvent in the petroleum hydrocarbon solution is any one of acetonitrile, acetic acid, 1,2-dichloroethane, tetrahydrofuran, methanol and ethanol.

10. The method for preparing fatty alcohols by catalytic oxidation of petroleum hydrocarbons according to claim 1, characterized in that: The hydroxyl groups of fatty alcohols are at the 2, 3 and 4 positions.

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