Large-aperture composite oxide catalyst, preparation thereof and method for preparing higher alcohol from ethanol

Abstract

The invention discloses a large-aperture composite oxide catalyst, a preparation method thereof and a method for preparing higher alcohol from ethanol. The large-aperture composite oxide catalyst comprises copper oxide, lanthanum oxide and aluminum oxide. The large-aperture composite oxide catalyst is prepared by a coprecipitation method, and a nonionic surfactant is added as a pore-enlarging agent in the preparation process. The invention provides a method for preparing higher alcohol from ethanol, a reaction device adopted by the method comprises a main reactor and an auxiliary reactor which are sequentially connected in series, the main reactor is filled with the large-aperture composite oxide catalyst in the first aspect, the auxiliary reactor is filled with a Cu-Zn-Al composite oxide catalyst for aldehyde ester hydrogenation, and the Cu-Zn-Al composite oxide catalyst is used for hydrogenation of higher alcohol. According to the method, the ethanol conversion rate and the yield of high-carbon fatty alcohol with more than C6 are improved.

Description

Technical Field

[0001] The invention relates to a macroporous composite oxide catalyst and a preparation method thereof, and a method for preparing higher alcohols from ethanol. Background Art

[0002] Due to the increasing depletion of fossil resources and the greenhouse effect caused by their use, the development and utilization of renewable biomass fuels have attracted more and more attention. Bioethanol, as a renewable clean fuel, has been widely used as a gasoline additive in Europe, the United States, Brazil and China. However, as a fuel, ethanol has the disadvantages of strong water absorption and low energy density. Compared with ethanol, butanol has an energy density close to that of gasoline, lower water solubility and lower heat of vaporization, and can be used directly without structural modification of existing engines, so it has the potential to become a new generation of biofuels to be promoted and used. Similar to butanol, higher alcohols such as hexanol and octanol can also be used as excellent fuel blending components, especially because they have a higher cetane number, so they are suitable for use as diesel additives to increase the oxygen content of diesel, thereby significantly reducing particulate matter and nitrogen oxides produced during diesel combustion. In addition to being used as fuel, these higher alcohols are also important industrial solvents and organic synthetic raw materials, and are widely used in coatings, rubber, plastics, cosmetics, flavors and other industries. C12-C20 fatty alcohols with higher carbon numbers are the main raw materials for detergents and surfactants, and are widely used in cleaning products, personal care products, cosmetics and other fields, with a large market demand. Hydrogenation of vegetable oils such as coconut oil and palm oil is currently the main production method for C12-C20 higher fatty alcohols. However, since the raw materials for its production are mainly concentrated in Southeast Asian countries such as Indonesia and Malaysia, the global fatty alcohol industry has a serious supply shortage. China also needs to import a large amount of higher fatty alcohols to meet the continuously growing market demand.

[0003] The dehydrogenation condensation of ethanol to produce higher alcohols is achieved through the Guerbet reaction mechanism, which mainly includes three steps: dehydrogenation of ethanol to produce acetaldehyde, acetaldehyde aldol condensation to produce crotonaldehyde, and crotonaldehyde hydrogenation to produce butanol. It involves multiple catalytic active sites such as metal centers and acid-base centers. Metal catalysts supported by porous solid acid-base materials are widely used in the dehydrogenation coupling reaction of ethanol to produce higher alcohols. For example, patent CN113578327A discloses a CuNiAl composite oxide catalyst for ethanol coupling to produce butanol, which has a high reaction temperature of 523 K and 3 MPa (N 2 )、LHSV=4.8 mL / (g cat ·h) showed an ethanol conversion rate of 39.8%, but the product was mainly n-butanol with a selectivity of 48.2%. Patent CN114130399A discloses an ordered mesoporous copper-rare earth metal-aluminum composite oxide catalyst, which has a high selectivity at 533 K and 3 MPa (N 2) showed an ethanol conversion rate of 48.1%, a butanol selectivity of 52.7%, and a C6-C8 higher alcohol selectivity of 21.5%. Patent CN113332989A discloses an alumina-supported copper-rare earth metal oxide catalyst, which has a high selectivity at 533 K and 3 MPa (N 2 ), liquid space velocity 2 mL / (g cat ·h), nitrogen / ethanol (v / v) = (250:1) reaction conditions show 51.3% ethanol conversion rate, 51.5% butanol selectivity and 22.4% higher alcohol selectivity. CN 117645528 A discloses a method for continuous catalytic conversion of ethanol to synthesize higher alcohols. The reaction is continuously carried out in a two-stage fixed bed reactor. The reaction device mainly comprises a main reactor and a secondary reactor in series. The main reactor is filled with a copper-based ethanol to higher alcohol multifunctional catalyst I (the catalyst is the same as the Cu-La in CN113976184 2 O 3 / Al 2 O 3 The secondary reactor is filled with catalyst Ⅱ for catalytic hydrogenation of aldehyde and ester compounds. The raw material ethanol is first converted into higher alcohols and aldehyde and ester byproducts through the main reactor and catalyst Ⅰ, and then the aldehyde and ester byproducts in the material are hydrogenated into alcohol products through the secondary reactor and catalyst Ⅱ. This method achieves an ethanol conversion rate of 62.46%, a butanol selectivity of 50.07% and a C 6 -C 12 Alcohol selectivity; however, the proportion of butanol with lower added value is relatively large, and the economic value of the reaction needs to be further improved.

[0004] In summary, to date, the existing heterogeneous catalysts for the production of higher alcohols from ethanol still have low selectivity for higher alcohols with higher carbon numbers than butanol, especially the production of higher value-added long-chain C12-C20 fatty alcohols by fixed-bed catalytic coupling of ethanol has not been reported.

[0005] The present invention provides a catalyst for continuous catalytic conversion of ethanol to synthesize higher alcohols and a method for preparing and preparing higher alcohols from ethanol. The reaction is continuously carried out in a two-stage fixed bed reactor, the main reactor is filled with a large-pore composite oxide catalyst (catalyst I), and the secondary reactor is filled with a Cu-Zn-Al composite oxide catalyst (catalyst II). Its outstanding feature is that the main reactor is filled with a large-pore composite oxide catalyst, and its larger pore size provides convenience for the diffusion of reactants and reaction intermediates, and is also conducive to the generation of higher alcohols with larger molecular weight, so that it not only has higher ethanol conversion activity, but also has higher selectivity for C6 and above high-carbon fatty alcohols, especially can produce C12-C20 long-chain higher fatty alcohols with higher added value, thereby opening up a new way to produce long-chain higher fatty alcohols, which is of great significance to solving the global higher fatty alcohol industry's dilemma of supply exceeding demand. Summary of the invention

[0006] The first technical problem to be solved by the present invention is to provide a large-pore composite oxide catalyst for the reaction of ethanol to higher alcohols, which has high catalytic activity and is conducive to the production of higher alcohols with relatively large molecular weight, thereby increasing the yield of higher alcohols above C6.

[0007] The second technical problem to be solved by the present invention is to provide a method for preparing a large-pore composite oxide catalyst for the reaction of ethanol to higher alcohols.

[0008] The third technical problem of the present invention is to provide a method for preparing higher alcohols from ethanol to further improve the ethanol conversion rate and the yield of high-carbon fatty alcohols above C6.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a macroporous composite oxide catalyst for the reaction of ethanol to higher alcohols, wherein the macroporous composite oxide catalyst comprises aluminum oxide, copper oxide and lanthanum oxide, and the content of each component in the macroporous composite oxide catalyst is expressed in mass percentage as follows:

[0011] Copper oxide 0.1%~6%

[0012] Lanthanum oxide 1%~15%

[0013] Alumina 79%~98.9%

[0014] The macroporous composite oxide catalyst is in granular form and has a specific surface area of ​​250-550 m 2 / g, pore volume is 1.0~2.0 cm 3 / g, and the average pore size is 10~30 nm.

[0015] Preferably, the macroporous composite oxide catalyst is prepared by coprecipitation, and a nonionic surfactant is added as a pore-enlarging agent during the preparation process. Further preferably, the nonionic surfactant is at least one of fatty alcohol polyoxyethylene ether, fatty alcohol amide, and the like.

[0016] Preferably, the content of each component in the large-pore composite oxide catalyst is expressed as follows in mass percentage:

[0017] Copper oxide 0.1%~5%

[0018] Lanthanum oxide 2%~12%

[0019] Alumina 83%~97.9%.

[0020] As a further preference, the content of each component in the large-pore composite oxide catalyst is expressed in mass percentage as follows:

[0021] Copper oxide 0.25%~3%

[0022] Lanthanum oxide 3%~12%

[0023] Alumina 85%~96.75%.

[0024] Preferably, the macroporous composite oxide catalyst is in granular form with a specific surface area of ​​300-550 m 2 / g, pore volume is 1.3~2.0 cm 3 / g, and an average pore size of 15-30 nm. It is further preferred that the large-pore composite oxide catalyst is in a granular form, and has a specific surface area of ​​300-400 m 2 / g, pore volume is 1.3~2.0 cm 3 / g, and the average pore size is 15~30 nm.

[0025] In a second aspect, the present invention provides a method for preparing a macroporous composite oxide catalyst for the reaction of ethanol to higher alcohols, comprising the following steps:

[0026] (1) Mixing and stirring the prepared copper, lanthanum and aluminum precursor salts and alkaline precipitant solution at 40-95° C. for 20-120 min to obtain a suspension;

[0027] (2) filtering the suspension to obtain a filter cake, and then washing the filter cake with water to obtain a wet filter cake;

[0028] (3) The wet filter cake is mixed with a nonionic surfactant and deionized water to form a slurry, which is then added to a reactor and mixed and reacted at 20-120°C for 1-12 hours;

[0029] (4) centrifuging the reaction solution obtained in step (3) to obtain a solid precipitate;

[0030] (5) Dry the solid precipitate in an oven at 40-120°C for 2-8 hours;

[0031] (6) The dried solid precipitate is placed in a muffle furnace and calcined at 300-800° C. in air or an inert gas atmosphere for 0.5-24 h to obtain the large-pore composite oxide catalyst.

[0032] In the above-mentioned method for preparing a large-pore composite oxide catalyst, the copper precursor may be at least one of soluble copper salts such as copper nitrate, copper chloride, copper acetate, and copper acetylacetonate, and the mass percentage concentration of the copper precursor salt in the copper precursor salt solution is 1 to 60%. The lanthanum precursor may be at least one of lanthanum nitrate, lanthanum acetate, and lanthanum acetylacetonate, and the mass percentage concentration of the lanthanum precursor salt in the lanthanum precursor salt solution is 3 to 60%. The aluminum precursor salt is at least one of soluble aluminum salts such as aluminum nitrate, aluminum sulfate, and aluminum chloride, and the mass percentage concentration of the aluminum precursor salt in the aluminum precursor salt solution is 5 to 60%. The alkaline precipitant may be at least one of alkaline substances such as sodium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water, and the mass percentage concentration of the alkaline precipitant in the alkaline precipitant solution is 5 to 75%. The ratio of the total amount of the copper, lanthanum and aluminum precursors to the amount of the alkaline precipitant is 1:0.5~1:5; the non-ionic surfactant is at least one of fatty alcohol polyoxyethylene ether, fatty alcohol amide, etc., and the mass percentage concentration of the non-ionic surfactant in the slurry prepared by mixing the wet filter cake, the non-ionic surfactant and deionized water is 5~50%.

[0033] In a third aspect, the present invention provides a method for preparing higher alcohols from ethanol, wherein the reaction device used in the method comprises a main reactor and a secondary reactor connected in series in sequence, the main reactor is filled with the large-pore composite oxide catalyst (catalyst I) described in the first aspect, and the secondary reactor is filled with a Cu-Zn-Al composite oxide catalyst for hydrogenation of aldehydes and esters; the method comprises the following steps:

[0034] First, ethanol is introduced into the main reactor to reduce the large-pore composite oxide catalyst, and a mixed gas of nitrogen and hydrogen is introduced into the secondary reactor to reduce the Cu-Zn-Al composite oxide catalyst; after the reduction is completed, ethanol is continuously added to the main reactor and converted into a mixture containing higher alcohols and aldehyde ester by-products through catalyst I, and the mixture containing higher alcohols and aldehyde ester by-products is continuously introduced into the secondary reactor, wherein the aldehyde ester by-products undergo a hydrogenation reaction with the hydrogen introduced into the secondary reactor under the action of the Cu-Zn-Al composite oxide catalyst to further convert into corresponding higher alcohol products.

[0035] The Cu-Zn-Al composite oxide catalyst of the present invention is a commonly used aldehyde ester hydrogenation catalyst. Generally, CuO, ZnO and Al in the Cu-Zn-Al composite oxide catalyst are 2 O 3 The mass percentages of are 10% to 60%, 5% to 40% and 5 to 80% respectively. Those skilled in the art can prepare the catalyst by themselves according to the methods reported in the literature, or use commercially available products.

[0036] Preferably, the method comprises the following steps:

[0037] (1) First, ethanol is introduced into the main reactor to reduce the macroporous composite oxide catalyst. The reduction conditions are as follows: temperature is 100-325°C (preferably 150-300°C), pressure is atmospheric pressure-6.0 MPa (preferably atmospheric pressure-5.0 MPa), and the liquid space velocity of ethanol is 0.2-6.0 mL / (g cat ·h) (preferably 0.5~5.0 mL / (g cat ·h)), the reduction time is 0.5~12h;

[0038] (2) A mixture of nitrogen and hydrogen is introduced into the secondary reactor to reduce the Cu-Zn-Al composite oxide catalyst. The reduction conditions are: 150-300°C, atmospheric pressure, and a volume ratio of 10:1 to 1:20 of H 2 With N 2 The mixed gas has a space velocity of 500 to 3000 h -1 , the reduction time is 1~6 h;

[0039] (3) After the reduction of the large-pore composite oxide catalyst and the Cu-Zn-Al composite oxide catalyst is completed, ethanol is continuously added to the main reactor and converted into a mixture containing higher alcohols and aldehyde ester by-products by the catalyst I, and the mixture containing higher alcohols and aldehyde ester by-products is continuously introduced into the secondary reactor, wherein the aldehyde ester by-products are further converted into corresponding higher alcohol products by hydrogenation reaction with hydrogen introduced into the secondary reactor under the action of the Cu-Zn-Al composite oxide catalyst;

[0040] The reaction conditions in the main reactor are: temperature of 150-325°C (preferably 200-300°C), pressure of normal pressure-6.0 MPa (preferably normal pressure-5.0 MPa), liquid space velocity of ethanol of 0.2-6.0 mL / (g cat ·h) (preferably 0.5~5.0mL / (g cat h ));

[0041] The reaction conditions in the secondary reactor are as follows: the temperature is 150-250°C (preferably 180-240°C), the pressure in the secondary reactor is controlled by the hydrogen introduced, the pressure is normal pressure-6.0 MPa (preferably normal pressure-5.0 MPa), the liquid space velocity of the raw material is 0.2-6.0 mL / (g cat ·h) (preferably 0.5~5.0 mL / (g cat ·h)), the molar ratio of hydrogen to ethanol raw material is 1~300:1 (preferably 5~100:1).

[0042] The higher alcohols described in the present invention include C4-C20 alcohols, namely, n-butanol, 2-ethylbutanol, n-hexanol, 2-ethylhexanol, n-octanol, 2-ethyloctanol, n-decanol, lauryl alcohol, myristyl alcohol, 1-hexadecanol, 1-octadecanol, 1-eicosanol and other high-carbon fatty alcohols.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] (1) When the large-pore composite oxide catalyst provided by the present invention is used in the reaction of ethanol to produce higher alcohols, its larger pore size and specific surface area are conducive to the diffusion of raw materials, reaction intermediates, etc. in the pore channels, especially conducive to the production of higher alcohols with larger relative molecular weight. Therefore, the catalyst has both high reaction activity and high selectivity for higher alcohols above C6: it not only has higher selectivity for C6-C10 high-carbon fatty alcohols, but also can produce C12-C20 long-chain higher fatty alcohols that are in short supply in the market.

[0045] (2) The large-pore alumina carrier provided by the present invention has both large pore size and high specific surface area. The large pore size significantly increases the diffusion rate of raw materials and reaction intermediates in the catalyst pores, and the high specific surface area makes copper highly dispersed on the catalyst surface, so that even at a lower Cu loading, it still maintains a high catalytic activity, thereby reducing the production cost of the catalyst. At the same time, the catalyst preparation method is simple and reliable, and the reaction conditions are relatively mild, which brings great advantages to the industrial application of the catalyst.

[0046] (3) The present invention develops a method for synthesizing higher alcohols by continuous catalytic conversion of ethanol. The method adopts a two-stage fixed bed reaction process: the reaction device mainly comprises a main reactor and a secondary reactor connected in series, the main reactor is loaded with a large-pore composite oxide catalyst (catalyst I), and the secondary reactor is loaded with a Cu-Zn-Al hydrogenation catalyst (catalyst II); the reaction raw material ethanol is first converted into higher alcohols and aldehyde ester by-products through the main reactor and catalyst I, and then the aldehyde ester by-products in the product are further hydrogenated and converted into alcohol products through the secondary reactor and catalyst II, thereby further improving the selectivity of higher alcohols in the product and reducing the complexity and cost of subsequent product separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The schematic diagram of the fixed bed reaction device for the dehydrogenation condensation of ethanol to produce higher alcohols is shown in FIG. The reaction device mainly comprises a main reactor and a secondary reactor connected in series. The main reactor is loaded with a large-pore composite oxide catalyst (catalyst I), and the secondary reactor is loaded with a commercial Cu-Zn-Al hydrogenation catalyst (catalyst II). The raw material ethanol enters from the bottom of the main reactor and flows through the catalyst bed from bottom to top. After the reaction, the material overflows from the upper part of the main reactor, while the raw material of the secondary reactor enters from the top of the reactor and flows through the catalyst bed from top to bottom. After the reaction, the material flows out from the bottom of the reactor; 1-nitrogen cylinder, 2-hydrogen cylinder, 3- 1-pressure reducing valve, 4-stop valve, 5-mass flowmeter, 6-ethanol raw material bottle, 7-high-pressure constant flow pump, 8-first three-way valve, 9-first non-return valve, 10-main reactor, 11-secondary reactor, 12-condenser, 13-condensate outlet, 14-condensate inlet, 15-filter, 16-back pressure valve, 17-product collection tank, 31-second three-way valve, 32-third three-way valve, 33-second pressure reducing valve, 34-second stop valve, 35-second mass flowmeter, 36-second non-return valve, 37-third non-return valve, 38-fourth non-return valve, 39-fifth non-return valve, 40-third stop valve. DETAILED DESCRIPTION

[0048] The present invention is further described below by means of specific embodiments, but the protection scope of the present invention is not limited thereto.

[0049] If no specific conditions are specified in the examples of the present invention, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be obtained by conventional technical means or purchased commercially.

[0050] like Figure 1 As shown, the reaction device comprises a main reactor 10 and a secondary reactor 11 connected in series, and the main reactor 10 and the secondary reactor 11 are fixed bed reactors. The main reactor comprises a main reactor feed port at the bottom and a main reactor discharge port at the top, and the secondary reactor comprises a secondary reactor feed port at the top and a secondary reactor discharge port at the bottom; the main reactor discharge port is connected to the secondary reactor feed port; the main reactor is filled with the large-pore composite oxide catalyst (catalyst I), and the secondary reactor is filled with a commercial Cu-Zn-Al composite oxide hydrogenation catalyst (catalyst II).

[0051] Furthermore, the reaction device also includes an ethanol raw material bottle 6, which is connected to the feed port of the main reactor 10; the reaction device also includes a nitrogen cylinder 1 and a hydrogen cylinder 2, the nitrogen cylinder 1 is connected to the feed port of the main reactor and the feed port of the auxiliary reactor; the hydrogen cylinder 2 is connected to the feed port of the auxiliary reactor 11.

[0052] Furthermore, the reaction device further comprises a condenser 12 and a product collection tank 17, the discharge port of the secondary reactor is connected to the feed port of the condenser 12, and the discharge port of the condenser 12 is connected to the product collection tank 17. Furthermore, the product collection tank 17 is also connected to a back pressure valve 16 via a filter 15.

[0053] Devices such as valves are conventional choices for controlling flow direction and flow rate in this field, and can be equipped as needed. In an embodiment of the present invention, the raw material bottle 6 is connected to the feed port of the main reactor through a high-pressure constant flow pump 7, a first three-way valve 8, and a first one-way valve 9 in sequence, and the discharge port of the main reactor 10 is connected to the feed port of the secondary reactor 11 through a second three-way valve 31; the nitrogen cylinder 1 is connected to the feed port of the main reactor 10 and the feed port of the secondary reactor 11 through a first pressure reducing valve 3, a first stop valve 4, a first mass flow meter 5, and a third three-way valve 32 respectively; the hydrogen cylinder 2 is connected to the feed port of the secondary reactor 11 through a second pressure reducing valve 33, a second stop valve 34, and a second mass flow meter 35 in sequence. Furthermore, in order to ensure safety, a second one-way valve 36 is provided between the third three-way valve 32 and the feed port of the main reactor 10; a third one-way valve 37 is provided between the third three-way valve 32 and the feed port of the secondary reactor 11; a fourth one-way valve 38 is provided between the second mass flow meter 35 and the feed port of the secondary reactor 11; and a fifth one-way valve 39 is provided between the discharge port of the secondary reactor 11 and the feed port of the condenser 12. Furthermore, the product collection tank 17 also has a product outflow port, which is controlled by a third stop valve 40.

[0054] The commercial Cu-Zn-Al composite oxide catalyst used in the examples of the present invention is produced by Nanjing Zunlong New Materials Technology Co., Ltd. and has a model number of QC-1.

[0055] Example 1

[0056] 56.2775 g Al(NO 3 ) 3 9H 2 O, 0.2912 g Cu(NO 3 ) 3 ·3H 2 O and 1.3 g La(NO 3 ) 3 6H 2O was dissolved in 100 mL of deionized water, and 37.2685 g of NaHCO 3 Dissolved in 250 mL of deionized water, then the two solutions were mixed at 80 ° C, stirred for 60 min to form a blue suspension, and filtered to obtain a filter cake. The filter cake was slurried and washed in 600 mL of deionized water for 60 min and then filtered, and repeated 3 times; the obtained filter cake was mixed with 13.2572 g of fatty alcohol polyvinyl ether (AEO-9) and 100 mL of deionized water to form a slurry, and then added to a reactor equipped with a polytetrafluoroethylene liner at 100 ° C for 6 h. The liquid after the reaction was centrifuged in a centrifuge to obtain a blue solid. The obtained solid was dried in an oven at 80 ° C for 6 h, and then the obtained solid was calcined at 600 ° C in a muffle furnace for 2 h to obtain catalyst Ⅰ-A. The specific surface area, pore volume and average pore size of catalyst Ⅰ-A were measured by N 2 The physical adsorption method is as follows: first, the sample is vacuum degassed at 200 °C for 4 h to remove the adsorbed moisture and impurity gases, and then N is heated at liquid nitrogen temperature (-196 °C). 2 Physical adsorption, and finally the adsorption-desorption isotherm of the sample was obtained according to the static method; the specific surface area of ​​the sample was calculated from the adsorption isotherm according to the Brunauer Emmett and Teller (BET) equation, and then the specific surface area of ​​the sample was calculated according to the single point method (P / P 0 =0.99) and the BJH equation were used to calculate the pore volume and average pore size from the desorption isotherm. The specific surface area of ​​the catalyst Ⅰ-A was found to be 320.2 m 2 / g, pore volume 1.7cm 3 / g, average pore size 20.1nm. CuO, La in catalyst Ⅰ-A 2 O 3 and Al 2 O 3 The mass percentages are 1.2%, 5.9% and 92.9% respectively.

[0057] Example 2

[0058] The preparation method of catalyst I-B is the same as that of Example 1, but Cu(NO 3 ) 2 ·3H 2 The amount of O was 0.5824 g. The specific surface area, pore volume and average pore diameter of catalyst I-B were determined in the same manner as in Example 1. The specific surface area of ​​catalyst I-B was 315.8 m 2 / g, pore volume 1.6 cm 3 / g, average pore size 20.6 nm. CuO, La 2 O 3 and Al 2 O3 The mass percentages are 2.3%, 5.9% and 91.8% respectively.

[0059] Example 3

[0060] The preparation method of catalyst I-C is the same as that of Example 1, except that the catalyst is calcined in the muffle furnace at a temperature of 500°C. The specific surface area, pore volume and average pore diameter of catalyst I-C are determined in the same manner as in Example 1. The specific surface area of ​​catalyst I-C is 321.0 m 2 / g, pore volume 1.5 cm 3 / g, average pore size 18.4 nm. CuO, La 2 O 3 and Al 2 O 3 The mass percentages are 1.2%, 6.0% and 92.8% respectively.

[0061] Comparative Example 1

[0062] The preparation method of catalyst I-D is the same as that of Cu-La in Chinese patent CN113976184. 2 O 3 / Al 2 O 3 The catalyst was prepared by the following method: 0.4562 g of copper nitrate (Cu(NO 3 ) 2 ·3H 2 O) and 0.4088 g lanthanum nitrate (La(NO 3 ) 3 6H 2 O) was added to 10 mL of anhydrous ethanol. After it was dissolved and mixed evenly, 2 g of commercial alumina carrier was added and impregnated for 4 hours. The above mixture was first dried on a rotary evaporator at 50°C and 0.01 MPa for 3 hours, and then rotary dried at 80°C and 0.01 MPa for 2 hours. The copper and lanthanum precursors were evenly loaded on the inner and outer surfaces of the alumina carrier. The dried solid material was placed in a muffle furnace and calcined in an air atmosphere at 450°C for 3 hours to obtain catalyst I-D. The method for determining the specific surface area, pore volume and average pore size of catalyst I-D was the same as in Example 1. The specific surface area of ​​catalyst I-C was measured to be 232.6 m 2 / g, pore volume 0.73 cm 3 / g, average pore size 7.6 nm. CuO, La 2 O 3 and Al 2 O 3 The mass percentages are 6.6%, 6.7% and 86.7% respectively.

[0063] Comparative Example 2

[0064] The preparation method of catalyst Ⅰ-E is the same as that of comparative example 1, but Cu(NO 3 ) 2 ·3H 2 O and La (NO 3 ) 3 6H 2 The specific surface area, pore volume and average pore diameter of catalyst Ⅰ-E were determined in the same manner as in Example 1. The specific surface area of ​​catalyst Ⅰ-E was 238 m 2 / g, pore volume 0.74 cm 3 / g, average pore size 7.7 nm. CuO, La 2 O 3 and Al 2 O 3 The mass percentages are 1.2%, 5.9% and 92.9% respectively.

[0065] Comparative Example 3

[0066] The preparation method of catalyst I-F is the same as that of comparative example 1, but Cu(NO 3 ) 2 ·3H 2 O and La (NO 3 ) 3 6H 2 The specific surface area, pore volume and average pore diameter of catalyst I-F were determined in the same manner as in Example 1. The specific surface area of ​​catalyst I-F was 235.4 m 2 / g, pore volume 0.74 cm 3 / g, average pore size 7.6 nm. CuO, La 2 O 3 and Al 2 O 3 The mass percentages are 2.4%, 5.8% and 91.8% respectively.

[0067] Example 6

[0068] Reaction device such as Figure 1 As shown, catalysts Ⅰ-A, Ⅰ-B, Ⅰ-C, Ⅰ-D, Ⅰ-E and IF (catalyst I) prepared in the above embodiments and comparative examples are respectively loaded into the main reactor of the fixed bed reactor, and the commercial Cu-Zn-Al composite oxide catalyst (catalyst II) is loaded into the secondary reactor of the fixed bed reactor.

[0069] The method described is carried out according to the following steps:

[0070] (1) First, ethanol was introduced into the main reactor to reduce the macroporous composite oxide catalyst. The reduction conditions were: temperature 250 °C, pressure normal pressure, and liquid space velocity of ethanol 1.0 mL / (g cat ·h), the reduction time is 4 h;

[0071] (2) A mixed gas of nitrogen and hydrogen was introduced into the secondary reactor to reduce the Cu-Zn-Al composite oxide catalyst. The reduction conditions were: 250°C, atmospheric pressure, and a volume ratio of 1 to 10 H 2 With N 2 The mixed gas has a space velocity of 1500 h -1 , the reduction time is 3 h;

[0072] (3) After the reduction of the large-pore composite oxide catalyst and the Cu-Zn-Al composite oxide catalyst is completed, ethanol is continuously added to the main reactor and converted into a mixture containing higher alcohols and aldehyde ester by-products by the catalyst I, and the mixture containing higher alcohols and aldehyde ester by-products is continuously introduced into the secondary reactor, wherein the aldehyde ester by-products are further converted into corresponding higher alcohol products by hydrogenation reaction with hydrogen introduced into the secondary reactor under the action of the Cu-Zn-Al composite oxide catalyst;

[0073] The reaction conditions in the main reactor are: temperature of 260°C, pressure of 5.0 MPa, liquid space velocity of ethanol of 1 mL / (g cat h);

[0074] The reaction conditions in the secondary reactor are as follows: the temperature is 220°C, the pressure in the secondary reactor is controlled by the hydrogen introduced, the pressure is 5.0 MPa, the liquid space velocity of the raw material is 1.0 mL / (g cat ·h), the molar ratio of hydrogen to ethanol raw materials is 11:1.

[0075] The reaction conditions are shown in Table 1. The obtained liquid product was analyzed by gas chromatography equipped with a flame ionization detector (FID) and an HP-5 column (30 m, 0.25 mm). 2-Ethylhexanol was used as an internal standard for the quantification of the liquid product.

[0076] The calculation method of ethanol conversion rate, higher alcohol selectivity and yield is as follows:

[0077]

[0078]

[0079]

[0080] The carbon mole number is the total mole number of carbon atoms contained in the product or raw material ethanol.

[0081] The reaction results are shown in Table 2.

[0082] Table 1 Summary of conditions for the two-stage fixed bed reaction of ethanol continuous dehydrogenation condensation to produce higher alcohols

[0083]

[0084] Table 2 Reaction performance of different catalysts in the continuous catalytic synthesis of higher alcohols by ethanol fixed bed

[0085]

[0086] As can be seen from Table 2, the ethanol conversion rate and high-carbon alcohol selectivity on the large-pore composite oxide catalyst are significantly higher than those prepared with commercial alumina with smaller pores as the carrier. In particular, it not only has a higher selectivity for high-carbon fatty alcohols above C6, but also can produce C12-C20 long-chain higher fatty alcohols that are in short supply in the market. Its larger pore size and specific surface area not only increase the diffusion rate of raw ethanol, reaction intermediates, etc. in its pore channels, but also facilitate the formation of high-carbon alcohols with larger molecular weights, thereby significantly improving the activity of the catalyst (even at a lower Cu loading, it still maintains a high ethanol conversion rate), and at the same time significantly improves the selectivity and yield of C6-C20 high-carbon alcohols with higher added value.

Claims

1. A macroporous composite oxide catalyst for the reaction of ethanol to higher alcohols, characterized in that: The large-pore composite oxide catalyst comprises aluminum oxide, copper oxide and lanthanum oxide. The content of each component in the large-pore composite oxide catalyst is expressed in mass percentage as follows: Copper oxide 0.1%~6% Lanthanum oxide 1%~15% Alumina 79%~98.9% The macroporous composite oxide catalyst is in granular form and has a specific surface area of ​​250-550 m 2 / g, pore volume is 1.0~2.0cm 3 / g, and the average pore size is 10~30 nm.

2. The macroporous composite oxide catalyst for the reaction of ethanol to higher alcohols according to claim 1, characterized in that: The content of each component in the macroporous composite oxide catalyst is expressed as follows in mass percentage: Copper oxide 0.1%~5% Lanthanum oxide 2%~12% Alumina 83%~97.9%.

3. The macroporous composite oxide catalyst for the reaction of ethanol to higher alcohols according to claim 2, characterized in that: The content of each component in the macroporous composite oxide catalyst is expressed as follows in mass percentage: Copper oxide 0.25%~3% Lanthanum oxide 3%~12% Alumina 85%~96.75%.

4. The macroporous composite oxide catalyst for the reaction of ethanol to higher alcohols according to claim 1, characterized in that: The large-pore composite oxide catalyst is in granular form and has a specific surface area of ​​300-550 m 2 / g, pore volume is 1.3~2.0cm 3 / g, and the average pore size is 15~30 nm.

5. The macroporous composite oxide catalyst for the reaction of ethanol to higher alcohols according to claim 4, characterized in that: The large-pore composite oxide catalyst is in granular form and has a specific surface area of ​​300-400 m 2 / g, pore volume is 1.3~2.0cm 3 / g, and the average pore size is 15~30 nm.

6. The macroporous composite oxide catalyst for the reaction of ethanol to higher alcohols according to any one of claims 1 to 5, characterized in that: The large-pore composite oxide catalyst is prepared by a coprecipitation method, and a nonionic surfactant is added as a pore-enlarging agent during the preparation process.

7. A method for preparing a macroporous composite oxide catalyst for ethanol to higher alcohols reaction according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: (1) Mixing and stirring the prepared copper, lanthanum and aluminum precursor salts and alkaline precipitant solution at 40-95° C. for 20-120 min to obtain a suspension; (2) filtering the suspension to obtain a filter cake, and then washing the filter cake with water to obtain a wet filter cake; (3) The wet filter cake is mixed with a nonionic surfactant and deionized water to form a slurry, which is then added to a reactor and mixed and reacted at 20-120°C for 1-12 hours; (4) centrifuging the reaction solution obtained in step (3) to obtain a solid precipitate; (5) Dry the solid precipitate in an oven at 40-120°C for 2-8 hours; (6) The dried solid precipitate is placed in a muffle furnace and calcined at 300-800° C. in air or an inert gas atmosphere for 0.5-24 h to obtain the large-pore composite oxide catalyst.

8. The preparation method according to claim 7, characterized in that: The nonionic surfactant is at least one of fatty alcohol polyoxyethylene ether, fatty alcohol amide, etc., and the mass percentage concentration of the nonionic surfactant in the slurry prepared by mixing the wet filter cake, the nonionic surfactant and deionized water is 5-50%.

9. A method for preparing higher alcohols from ethanol, characterized in that: The reaction device used in the method comprises a main reactor and a secondary reactor connected in series, the main reactor is filled with the large-pore composite oxide catalyst according to any one of claims 1 to 6, and the secondary reactor is filled with a Cu-Zn-Al composite oxide catalyst for hydrogenation of aldehydes and esters; the method comprises the following steps: First, ethanol is introduced into the main reactor to reduce the large-pore composite oxide catalyst, and a mixed gas of nitrogen and hydrogen is introduced into the secondary reactor to reduce the Cu-Zn-Al composite oxide catalyst; after the reduction is completed, ethanol is continuously added to the main reactor and converted into a mixture containing higher alcohols and aldehyde ester by-products through the large-pore composite oxide catalyst, and the mixture containing higher alcohols and aldehyde ester by-products is continuously introduced into the secondary reactor, wherein the aldehyde ester by-products undergo a hydrogenation reaction with the hydrogen introduced into the secondary reactor under the action of the Cu-Zn-Al composite oxide catalyst to further convert into corresponding higher alcohol products.

10. The method according to claim 9, characterized in that: The method specifically comprises the following steps: (1) First, ethanol is introduced into the main reactor to reduce the macroporous composite oxide catalyst. The reduction conditions are as follows: temperature is 100-325°C (preferably 150-300°C), pressure is atmospheric pressure-6.0 MPa (preferably atmospheric pressure-5.0 MPa), and the liquid space velocity of ethanol is 0.2-6.0 mL / (g cat ·h) (preferably 0.5~5.0 mL / (g cat ·h)), the reduction time is 0.5~12 h; (2) A mixed gas of nitrogen and hydrogen is introduced into the secondary reactor to reduce the Cu-Zn-Al composite oxide catalyst. The reduction conditions are: 150-300°C, normal pressure, a mixed gas of H2 and N2 with a volume ratio of 10:1-1:20, and a space velocity of 500-3000 h -1 , the reduction time is 1~6 h; (3) After the reduction of the large-pore composite oxide catalyst and the Cu-Zn-Al composite oxide catalyst is completed, ethanol is continuously added to the main reactor, and converted into a mixture containing higher alcohols and aldehyde ester by-products by the large-pore composite oxide catalyst, and the mixture containing higher alcohols and aldehyde ester by-products is continuously introduced into the secondary reactor, wherein the aldehyde ester by-products are further converted into corresponding higher alcohol products by hydrogenation reaction with hydrogen introduced into the secondary reactor under the action of the Cu-Zn-Al composite oxide catalyst; The reaction conditions in the main reactor are: temperature of 150-325°C (preferably 200-300°C), pressure of normal pressure-6.0 MPa (preferably normal pressure-5.0 MPa), liquid space velocity of ethanol of 0.2-6.0 mL / (g cat ·h) (preferably 0.5~5.0 mL / (g cat h )); The reaction conditions in the secondary reactor are as follows: the temperature is 150-250°C (preferably 180-240°C), the pressure in the secondary reactor is controlled by the hydrogen introduced, the pressure is normal pressure-6.0 MPa (preferably normal pressure-5.0 MPa), the liquid space velocity of the raw material is 0.2-6.0 mL / (g cat ·h) (preferably 0.5~5.0 mL / (g cat ·h)), the molar ratio of hydrogen to ethanol raw material is 1~300:1 (preferably 5~100:1).

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