Method for preparing isobutanol by directional conversion of methanol and ethanol

Abstract

The invention provides a method for preparing isobutanol by directional conversion of methanol and ethanol, which comprises the following steps: by taking methanol and ethanol as raw materials, converting methanol and ethanol into isobutanol under the action of a Cu-doped composite metal oxide catalyst, a precursor of the catalyst is hydrotalcite-like, Cu in the catalyst is dispersed in a carrier in an atomic scale, and the loading capacity of Cu is 0.1-1.5 wt%. The Cu-doped composite metal oxide solid acid-base catalyst designed and prepared by the invention is easy to synthesize, the Cu species are highly dispersed on the oxide carrier, the catalyst has the characteristics of high activity, high selectivity and high stability in the reaction for preparing isobutanol by directional conversion of methanol and ethanol, and under the conditions of 300 DEG C and normal pressure, the conversion rate of ethanol is 99.5%, the selectivity of isobutanol is higher than 60%, and the catalyst is suitable for industrial production. In a 600h stability test, the ethanol conversion rate is greater than 80%, and the C-C coupling product selectivity is greater than 80%; meanwhile, the product is easy to separate, the whole process has economical efficiency and practicability, the sustainable development concept is met, and the method has good industrial application prospects in the field of biomass conversion.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical catalysis, and particularly relates to a method for the directional conversion of methanol and ethanol into isobutanol. Background Art

[0002] Under the background of "dual carbon", the efficient utilization of renewable energy has become an inevitable trend. Among them, the catalytic conversion of biomass methanol and ethanol to prepare high-value oxygenated chemicals has become an important research frontier. Through the catalytic high-value conversion of methanol and ethanol, important bulk chemicals such as acrolein, isobutanol / aldehyde, and aromatic oxygenated compounds can be obtained, and the reaction will go through processes such as dehydrogenation, dehydration, coupling, and hydrogen transfer. Isobutanol (C4H9OH) can be used to produce isobutyl ester products, as food additives or for the production of chemicals such as coatings, plasticizers, extractants, and synthetic drugs. At the same time, as a branched-chain alcohol, isobutanol has a higher octane number than straight-chain alcohols, has fuel characteristics closer to gasoline, has a high calorific value, is not easily volatile, and is immiscible with water. Due to the above advantages, isobutanol has received extensive attention as an ideal biofuel substitute. The use of isobutanol as an oil additive has been successfully applied abroad, but its low production capacity and high production cost limit its application. The traditional synthesis methods of isobutanol are mainly petroleum-based routes (such as propylene carbonylation), which require the use of noble metal catalysts (such as rhodium) and high-pressure conditions (1-3 MPa). The propylene hydroformylation method, with its high selectivity, easy availability of raw materials, and mature industrialization foundation, is still the mainstream process for producing isobutanol at present. However, its dependence on noble metals and the requirement for high-pressure equipment limit its application on a small and medium scale. In the future, it may be necessary to further enhance its competitiveness by developing non-noble metal catalysts, coupling bio-based raw materials, or optimizing the separation process. In recent years, the directional catalytic coupling of biomass-based lower alcohols (such as methanol and ethanol) to isobutanol has become a research hotspot.

[0003] Researchers such as Wingad prepared a ruthenium catalyst containing a phosphine ligand. Under the conditions of 180 °C, n(CH3OH):n(CH3CH2OH) = 14.4:1, and with the addition of the base NaOMe, the reaction was carried out for 20 h to obtain a maximum isobutanol selectivity of 99.8%, and at this time the ethanol conversion rate was 75.2% [Chemical Communications, 2016, 52(29): 5202-5204.]. Homogeneous catalysts are complex to prepare, difficult to separate from the products, and the addition of strong bases will corrode the equipment, which does not meet the requirements of economic, safe and environmental protection in actual application production. Therefore, heterogeneous catalysts applied to fixed-bed reactors are more conducive to large-scale continuous production. It has been reported that flower-shaped mesoporous hydroxyapatite-supported oxides are used as catalysts, which can catalyze the co-conversion of methanol and ethanol. The methanol conversion rate is 20-35%, and the ethanol conversion rate is 40-80%; the products are mainly propanol and butanol, among which the selectivity of propanol is greater than 30%, and the selectivity of butanol is 34-50% [Chinese Patent, CN 105562046 A]. Therefore, by reasonably designing the structure of heterogeneous catalysts, the cross-coupling of methanol and ethanol can be achieved, and the difficulty lies in the regulation of product selectivity. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing isobutanol based on methanol and ethanol in view of the deficiencies in the current technology. This method uses methanol and ethanol as raw materials, and reacts under the action of a Cu-doped composite metal oxide catalyst to obtain isobutanol. The reaction conditions are mild, the process flow is short, the reaction process is clean, the product selectivity is high, and the economy is good. It is a green isobutanol production process route.

[0005] The Cu-doped composite metal oxide catalyst disperses a small amount of copper atoms at the atomic level in the carrier by the co-precipitation method, enabling the catalyst to simultaneously have the ability of hydrogen transfer and coupling. After methanol and ethanol are activated, the corresponding aldehydes are obtained, and cross-coupling gives isobutenal. The in-situ generated hydrogen realizes hydrogen transfer on the catalyst surface to obtain the product isobutanol, without the need to additionally add H2. The catalyst has high activity, high selectivity for the target product isobutanol, and good stability, and maintains excellent catalytic performance in a 600 h test.

[0006] The technical solution of the present invention is as follows:

[0007] A method for the directional conversion of methanol and ethanol to isobutanol, which includes using methanol and ethanol as raw materials and converting methanol and ethanol into isobutanol under the action of a Cu-doped composite metal oxide catalyst; the precursor of the catalyst is hydrotalcite-like, and Cu in the catalyst is highly dispersed in the carrier, and the Cu loading is 0.1-1.5 wt%.

[0008] Furthermore, the molar ratio of divalent / trivalent cations in the catalyst is 2-5, the divalent cations are magnesium and copper, and the trivalent cations are aluminum.

[0009] Furthermore, a fixed-bed atmospheric pressure reactor is selected, and the reaction temperature is 150 - 350 °C. Further, the reaction temperature is 250 - 320 °C.

[0010] Furthermore, the mass space velocity is 0.5 - 12.0 h -1 , and further, the mass space velocity is 0.6 - 2.5 h -1 , specifically, the mass space velocity refers to the ratio of the mass flow rate of ethanol to the catalyst loading.

[0011] Furthermore, the methanol and ethanol raw materials are introduced into the reactor loaded with the catalyst through a carrier gas. The reaction pressure is 0.1 - 1 MPa, and the reaction gas flow rate is 20 - 200 mL / min.

[0012] Furthermore, the carrier gas is nitrogen, argon or hydrogen.

[0013] Furthermore, the volume ratio of methanol to ethanol is 1:1 - 24:1.

[0014] Furthermore, the hydrotalcite-like material is obtained by the co-precipitation method. The precipitants used in the co-precipitation method include at least two of sodium carbonate, sodium hydroxide, potassium carbonate and potassium hydroxide. The precipitant adjusts the final solution pH to 8 - 11, the aging temperature is 35 - 65 °C, and the aging time is 2 - 18 hours.

[0015] Furthermore, the hydrotalcite-like material is filtered, washed, dried and calcined to obtain the catalyst.

[0016] Furthermore, the calcination temperature is 300 - 600 °C, and the calcination time is 0.5 - 4 hours.

[0017] The beneficial effects of the present invention are as follows:

[0018] (1) The present invention has the advantages of short process flow and environmental friendliness.

[0019] (2) The Cu-doped composite metal oxide solid acid-base catalyst designed and prepared by the present invention is easy to synthesize. The Cu species are highly dispersed on the oxide support. The catalyst is a mixed oxide spinel structure. A very small amount of Cu is highly dispersed therein and forms a bond with O, existing in the form of Cu + , which is not easy to aggregate into clusters, thus facilitating the activation and dehydrogenation of methanol and ethanol, promoting the hydrogen transfer process, and synergistically acting with the acid-base active centers of the oxide to promote the directional conversion of isobutanol. It has the characteristics of high activity, high selectivity and high stability in the reaction of the directional conversion of methanol and ethanol to isobutanol. Under the conditions of 300 °C and atmospheric pressure, the conversion rate of ethanol is 99.5%, the selectivity of isobutanol reaches 60.4%, and in the 600 h stability test, the ethanol conversion rate is greater than 80%, and the selectivity of C-C coupling products is greater than 80%.

[0020] (3) When the solid acid-base catalyst provided by the present invention is used in the methanol-ethanol coupling reaction, the products are easy to separate. The whole process is both economical and practical, in line with the concept of sustainable development, and has good industrial application prospects in the field of biomass conversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 XRD patterns (a, b) of CuMgAl-LDH and CuMgAlO with different copper contents in Example 1 x .

[0022] Figure 2 XPS spectra and Auger spectra (a, b) of 0.25CuMgAlO x , 0.5CuMgAlO x catalysts in Example 1 and Comparative Example 5

[0023] Figure 3 Variation diagram of the conversion rate of ethanol and the selectivity of isobutanol over 600 h of reaction time under the 0.25CuMgAlO x catalyst in Example 1.

[0024] Example 1

[0025] Taking the preparation of 0.25CuMgAlO x catalyst as an example, the preparation process is as follows:

[0026] (1) Weigh 0.0272 g of Cu(NO3)2·3H2O, 11.5096 g of Mg(NO3)2·6H2O and 5.6270 g of Al(NO3)3·9H2O, dissolve them in 50 mL of deionized water and stir evenly;

[0027] (2) Weigh 4.2414 g of Na2CO3 and 2.4072 g of NaOH, dissolve them in 50 mL of ionized water to prepare a mixed alkali solution;

[0028] (3) Inject the mixed metal salt solution into the alkali solution at a speed of 10 mL / min, adjust the pH value with 3 mol / L NaOH solution under stirring in a 65 °C water bath, adjust the pH to 10, and age for 18 h at this pH and temperature;

[0029] (4) Filter the above-mentioned mixed solution after aging, wash it until neutral, and then place it in an oven at 50 °C to dry for 12 h;

[0030] (5) Calcinate in an air atmosphere at 600 °C for 2 h, denoted as 0.25CuMgAlO x .

[0031] (6) Change the content of copper nitrate in step (1), and the ratio of n(Cu):n(Mg):n(Al) will change accordingly. The preparation method is the same as the above steps, corresponding to Nos. 1-4 in Table 1. From Figure 1 and Figure 2 it can be seen that Cu atoms are distributed at the atomic level on the carrier and form bonds with O, existing in the form of Cu + .

[0032] The preparation conditions and processes of other catalysts are the same as those in Example 1. The corresponding relationship between the sample numbers and the preparation conditions is shown in Table 1.

[0033] Table 1 Corresponding relationship between sample numbers and preparation conditions in Example 1

[0034]

[0035] Example 2

[0036] 0.25CuMgAlO x The catalyst is used for the cross-coupling of methanol and ethanol to prepare isobutanol under different methanol and ethanol partial pressures.

[0037] Using methanol and ethanol as raw materials, the cross-coupling reaction of isobutanol is carried out in a fixed-bed reactor. The reaction conditions are as follows: The catalyst is loaded in a fixed-bed reactor with an inner diameter of 8 mm, at atmospheric pressure, the reaction temperature is 300 °C, methanol and ethanol are introduced into the reactor by nitrogen bubbling, the mass space velocity is 0.97 h -1 , the total flow rate of the reaction gas is 30 mL / min. After the reaction is stable, the liquid product is collected by a 0 °C cold trap for analysis, and the conversion rates of methanol and ethanol and the selectivity of the products are calculated by the normalization method. The results are shown in Table 2. When the volume ratio of methanol to ethanol is 16:1, the conversion rate of ethanol reaches the maximum of 99.5%, and the selectivity of isobutanol is the highest.

[0038] Table 2 Ethanol activity and isobutanol selectivity of 0.25CuMgAlO x catalyst at different methanol-ethanol ratios

[0039]

[0040] Example 3

[0041] Different CuMgAlO x catalysts are used for the cross-coupling of methanol and ethanol to prepare isobutanol.

[0042] Using methanol and ethanol as raw materials, the cross-coupling reaction of isobutanol is carried out in a fixed-bed reactor. The reaction conditions are as follows: The catalyst is loaded in a fixed-bed reactor with an inner diameter of 8 mm, at atmospheric pressure, the reaction temperature is 300 °C, methanol and ethanol are introduced into the reactor by nitrogen bubbling, where the partial pressure of methanol is 5.6 kPa and the partial pressure of ethanol is 0.4 kPa, and the mass space velocity is 0.97 h-1 With a total reaction gas flow rate of 30 mL / min, after the reaction stabilized, the liquid product was collected using a 0 °C cold trap for analysis. The conversion rates of methanol and ethanol and the selectivity of the products were calculated using the normalization method. The results are shown in Table 3. When the Cu loading was 0.25 wt%, the conversion rate of ethanol reached 99.5%, and at this time, the selectivity of isobutanol was the highest.

[0043] Table 3 Ethanol activity and isobutanol selectivity of different catalysts

[0044]

[0045]

[0046] Example 4

[0047] The ratio of M 2+ / M 3+ in the hydrotalcite precursor was changed, and the preparation method was the same as in Example 1. This catalyst was used for the cross-coupling of methanol and ethanol to produce isobutanol.

[0048] The cross-coupling reaction of isobutanol was carried out in a fixed-bed reactor using methanol and ethanol as raw materials. The reaction conditions were as follows: The catalyst was loaded in a fixed-bed reactor with an inner diameter of 8 mm, at atmospheric pressure, the reaction temperature was 300 °C, methanol and ethanol were introduced into the reactor by nitrogen bubbling, where the partial pressure of methanol was 5.6 kPa, the partial pressure of ethanol was 0.4 kPa, and the mass space velocity was 0.97 h -1 ,with a total reaction gas flow rate of 30 mL / min. After the reaction stabilized, the liquid product was collected using a 0 °C cold trap for analysis. The conversion rates of methanol and ethanol and the selectivity of the products were calculated using the normalization method. The results are shown in Table 4. When M 2+ / M 3+ was 3, the catalyst activity was optimal.

[0049] Table 4 Corresponding relationship between ethanol activity and isobutanol selectivity of catalysts with different M 2+ / M 3+ ratios

[0050]

[0051] Example 5

[0052] The 0.25CuMgAlO x catalyst in Example 1 was used to catalyze the cross-coupling of methanol and ethanol to produce isobutanol at different reaction temperatures.

[0053] The cross-coupling reaction of isobutanol is carried out in a fixed-bed reactor with methanol and ethanol as raw materials. The reaction conditions are as follows: A catalyst is loaded in a fixed-bed reactor with an inner diameter of 8 mm, at atmospheric pressure, the reaction temperature is 250 - 350 °C, methanol and ethanol are introduced into the reactor by nitrogen bubbling, where the partial pressure of methanol is 5.6 kPa, the partial pressure of ethanol is 0.4 kPa, and the mass space velocity is 0.97 h -1 , the total flow rate of the reaction gas is 30 mL / min. After the reaction is stable, the liquid product is collected using a 0 °C cold trap for analysis, and the conversion rates of methanol and ethanol and the selectivity of the products are calculated by the normalization method. The results are shown in Table 5. As the reaction temperature increases, the conversion rate of ethanol increases significantly, reaching a maximum of 99.5% at 300 °C, and the selectivity of isobutanol at this temperature is 60.4%.

[0054] Table 5 Catalytic activity of 0.25CuMgAlOx catalyst for ethanol and selectivity of isobutanol in Example 1 at different reaction temperatures

[0055]

[0056] Example 6

[0057] The cross-coupling of methanol and ethanol to produce isobutanol is catalyzed by 0.25CuMgAlO in Example 1 at different mass space velocities x catalyst.

[0058] The cross-coupling reaction of isobutanol is carried out in a fixed-bed reactor with methanol and ethanol as raw materials. The reaction conditions are as follows: A catalyst is loaded in a fixed-bed reactor with an inner diameter of 8 mm, at atmospheric pressure, the reaction temperature is 300 °C, methanol and ethanol are introduced into the reactor by nitrogen bubbling, where the partial pressure of methanol is 5.6 kPa, the partial pressure of ethanol is 0.4 kPa, and the mass space velocity is 0.97 - 7.76 h -1 , the total flow rate of the reaction gas is 30 mL / min. After the reaction is stable, the liquid product is collected using a 0 °C cold trap for analysis, and the conversion rates of methanol and ethanol and the selectivity of the products are calculated by the normalization method. The results are shown in Table 6. At 300 °C and a mass space velocity of 0.97, the conversion rate of ethanol is 99.5%, and the selectivity of isobutanol is the highest, at 60.4%.

[0059] Table 6 Catalytic activity of 0.25CuMgAlOx catalyst for ethanol and selectivity of isobutanol in Example 1 at different mass space velocities

[0060]

[0061]

[0062] Example 7

[0063] The cross-coupling of methanol and ethanol to produce isobutanol under different carrier gas atmospheres

[0064] Using the 0.25CuMgAlO catalyst in Example 1 x catalyst, at atmospheric pressure, the reaction temperature was 300 °C, methanol and ethanol were bubbled into the reactor by hydrogen, where the partial pressure of methanol was 5.6 kPa, the partial pressure of ethanol was 0.4 kPa, and the partial pressure of hydrogen was 94 kPa. The mass space velocity was 0.97 h -1 . The ethanol conversion was 92.8%, the isobutanol selectivity was 65.4%, the isobutyraldehyde selectivity was 3.7%, and the cross-coupling product selectivity was 72.8%, indicating that the catalyst could also exhibit excellent cross-coupling selectivity in a reducing atmosphere.

[0065] Example 8

[0066] 0.25CuMgAlO x Catalyst for catalytic cross-coupling of methanol and ethanol to isobutanol stability test experiment.

[0067] Using methanol and ethanol as raw materials, the reaction of methanol and ethanol to isobutanol was carried out in a fixed-bed reactor. The reaction conditions were as follows: 10 g of catalyst was loaded in a fixed-bed reactor with an outer diameter of 60 mm, an inner diameter of 38 mm, and a length of 480 mm. At atmospheric pressure, the reaction temperature was 300 °C. After the reaction was stabilized by injecting a liquid with a volume ratio of methanol:ethanol of 16:1 at a rate of 3 mL / min into the reaction tube through a liquid feed pump, the liquid products were collected every 12 h, and the reaction raw materials and products were analyzed by chromatography using on-line chromatography. The conversion and selectivity remained stable within a reaction time of 600 h. As shown in the appendix Figure 3 , the ethanol conversion was greater than 80%, and the C-C coupling product selectivity was greater than 80%.

[0068] Comparative Example 1

[0069] Magnesium nitrate and aluminum nitrate were weighed according to the ratio of n(Mg):n(Al) = 3:1, and the catalyst was named Mg3AlO x , and the loading amount of the active metal was 0 wt%. The remaining preparation process was the same as that in Example 1.

[0070] Using methanol and ethanol as raw materials, the cross-coupling reaction of isobutanol was carried out in a fixed-bed reactor. The reaction conditions were as follows: The catalyst was loaded in a fixed-bed reactor with an inner diameter of 8 mm. At atmospheric pressure, the reaction temperature was 300 °C. Methanol and ethanol were bubbled into the reactor by nitrogen, and the mass space velocity was 0.97 h -1 , the total flow rate of the reaction gas was 30 mL / min. After the reaction was stabilized, the liquid products were collected using a 0 °C cold trap for analysis, and the conversion of methanol and ethanol and the selectivity of the products were calculated by the normalization method.

[0071] Comparative Example 2

[0072] Cu / MgO was selected as the catalyst, and the Cu loading was 0.25 wt%.

[0073] 0.5 g of commercial MgO was taken and dried in a gas flow oven at 120 °C for 2 h to remove the physically adsorbed water on the surface; then, at 25 °C, 8.35 μL of a 0.15 g / mL Cu(NO3)2 aqueous solution was used to impregnate the magnesium-aluminum hydrotalcite in an equal volume, and it was left standing for 1 h; then the mixture after standing was dried in an oven at 50 °C for 12 h, and then the above dried product was calcined in an air atmosphere at 600 °C for 2 h; the testing process was the same as that in Comparative Example 1.

[0074] Comparative Example 3

[0075] Cu / Al2O3 was selected as the catalyst, and the Cu loading was 0.25 wt%.

[0076] 0.5 g of commercial Al2O3 was taken and dried in a gas flow oven at 120 °C for 2 h to remove the physically adsorbed water on the surface; then, at 25 °C, 8.5 μL of a 0.15 g / mL Cu(NO3)2 aqueous solution was used to impregnate the magnesium-aluminum hydrotalcite in an equal volume, and it was left standing for 1 h; then the mixture after standing was dried in an oven at 50 °C for 12 h, and then the above dried product was calcined in an air atmosphere at 600 °C for 2 h; the testing process was the same as that in Comparative Example 1.

[0077] Comparative Example 4

[0078] Cu / MgAlO x was selected as the catalyst, and the Cu loading was 0.25 wt%.

[0079] 0.5 g of the magnesium-aluminum hydrotalcite prepared in Comparative Example 1 was taken and dried in a gas flow oven at 120 °C for 2 h to remove the physically adsorbed water on the surface; then, at 25 °C, 8.15 μL of a 0.15 g / mL Cu(NO3)2 aqueous solution was used to impregnate the magnesium-aluminum hydrotalcite in an equal volume, and it was left standing for 1 h; then the mixture after standing was dried in an oven at 50 °C for 12 h, and then the above dried product was calcined in an air atmosphere at 600 °C for 2 h; the testing process was the same as that in Comparative Example 1.

[0080] Comparative Example 5

[0081] 2.5CuMgAlO with a high Cu loading x was selected as the catalyst.

[0082] The preparation process was the same as that in Example 1, but the Cu loading was 2.5%, and the testing process was the same as that in Comparative Example 1. The results are shown in Table 4. When the Cu loading was high, Cu aggregated into clusters ( Figure 2 ), which promoted the dehydrogenation process, and the products were mainly formaldehyde and acetaldehyde. At this time, the selectivity of the C-C coupling products was very low, indicating that the high-loading CuMgAlO x catalyst was not conducive to the formation of isobutanol.

[0083] The activity and selectivity of the comparative catalyst are shown in Table 7. By comparing with the catalyst of Example 1, it is illustrated that the acid-base sites of the active metal and the support synergistically regulate the directional conversion of methanol and ethanol to isobutanol.

[0084] Table 7 Ethanol activity and isobutanol selectivity of the comparative catalyst

[0085]

[0086] Comparative Example 6

[0087] 0.25CuMgAlO x The catalyst catalyzes different reaction raw materials and their product selectivities.

[0088] Using the 0.25CuMgAlO x catalyst in Example 1, a single product of methanol or ethanol was introduced into the reactor by nitrogen bubbling, and other test conditions were the same as those in Comparative Example 1. The activity and selectivity of the comparative catalyst are shown in Table 8. When the reactant is ethanol, the conversion rate of ethanol is 29.1%, and the products are n-butanol and higher alcohols, indicating that when methanol is present in the reactants, the 0.25CuMgAlO x catalyst catalyzes the conversion of ethanol more easily. When only methanol is fed, the reaction dehydrates to form dimethyl ether, and no other products are detected. This may be because methanol molecules do not contain β-H, which hinders the aldol condensation and thus results in no self-condensation products.

[0089] Table 8 Preparation of higher carbon oxygenates from different raw materials

[0090]

[0091] The above are only individual embodiments of the present invention and are not intended to limit the present invention. Any modifications, substitutions, and decorations made within the scope of the patent application of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for the directional conversion of methanol and ethanol to isobutanol, characterized in that: It includes converting methanol and ethanol into isobutanol under the action of a Cu-doped composite metal oxide catalyst with methanol and ethanol as raw materials; the precursor of the catalyst is hydrotalcite-like, Cu atoms in the catalyst are atomically dispersed in the carrier, and the Cu loading is 0.1-1.5 wt%.

2. The method for the directional conversion of methanol and ethanol to isobutanol according to claim 1, characterized in that: The molar ratio of divalent / trivalent cations in the catalyst is 2-5, the divalent cations are magnesium and copper, and the trivalent cations are aluminum.

3. The method for the directional conversion of methanol and ethanol to isobutanol according to claim 1, characterized in that: A fixed-bed atmospheric-pressure reactor is selected, and the reaction temperature is 150-350 °C.

4. The method for the directional conversion of methanol and ethanol to isobutanol according to claim 1, wherein: The mass space velocity is 0.5 to 12.0 h -1 .

5. A method for the directional conversion of methanol and ethanol to isobutanol according to claim 1 or 3, characterized in that: The methanol and ethanol raw materials are introduced into the reactor loaded with the catalyst through a carrier gas, the reaction pressure is 0.1-1 MPa, and the reaction gas flow rate is 20-200 mL / min.

6. The method for the directional conversion of methanol and ethanol to isobutanol according to claim 5, characterized in that: The carrier gas is nitrogen, argon or hydrogen.

7. A method for the directional conversion of methanol and ethanol to isobutanol according to claim 1, characterized in that: The volume ratio of the methanol to the ethanol is 1:1-24:

1.

8. A method for the directional conversion of methanol and ethanol to isobutanol according to claim 1, characterized in that: The hydrotalcite-like is obtained by the co-precipitation method. The precipitants used in the co-precipitation method include at least two of sodium carbonate, sodium hydroxide, potassium carbonate and potassium hydroxide. The precipitant adjusts the final solution pH to 8-11, the aging temperature is 35-65 °C, and the aging time is 2-18 h.

9. A method for the directional conversion of methanol and ethanol to isobutanol as claimed in claim 1 or 8, characterized in that: The catalyst is obtained by filtering, washing, drying and calcining the hydrotalcite-like.

10. The method for the directional conversion of methanol and ethanol to isobutanol according to claim 9, characterized in that: The calcination temperature is 300-600 °C, and the calcination time is 0.5-4 h.

Images