Catalyst for synthesizing alpha-olefin and co-producing fatty aldehyde as well as preparation method and application of catalyst

Abstract

The invention belongs to the technical field of organic synthesis, and discloses a catalyst for synthesizing alpha-olefin and coproducing fatty aldehyde as well as a preparation method and application of the catalyst. The invention relates to a catalyst for synthesizing alpha-olefin and co-producing fatty aldehyde. The catalyst comprises dehydrogenation and dehydration active sites, a dispersing aid and a carrier, the dispersity of dehydrogenation active sites is greater than 31.0%; and the concentration of a dehydration active site is 4.5-9.0 [mu] mol / g. According to the catalyst, dehydrogenation active sites and dehydration active sites are introduced at the same time, the dispersity of the dehydrogenation active sites and the concentration of the dehydration active sites are controlled, and the purposes of dehydration and dehydrogenation are achieved. Transition metal is creatively used for preparing fatty aldehyde and alpha-olefin through dehydrogenation and dehydration of fatty alcohol, stacking and covering of active components are inhibited through freezing impregnation in the preparation process, and the use amount of each component is controlled, so that dehydrogenation and dehydration active sites can play a role at the same time. The catalyst has alcohol dehydrogenation and hydroxyl dehydration performances, is used for synthesis of alpha-olefin from fatty alcohol and co-production of fatty aldehyde, and can produce two high-added-value products at the same time by changing the product proportion through regulation and control of parameters.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic synthesis, and particularly relates to a catalyst for synthesizing α-olefins and co-producing fatty aldehydes, a preparation method thereof, and an application thereof. Background Art

[0002] Olefins are very important basic chemical raw materials. Currently, about 75% of petrochemical products are derived from olefins, especially the demand for α-olefins is increasing day by day. The uses of α-olefins are very extensive. In the production of high-value-added polymer products, it can be used as a comonomer for polyethylene and a raw material for poly-α-olefins; in the field of surfactants, it can be used as a raw material for alkyl sulfonates, alkyl benzene sulfonates, alkyl phenols, higher alcohols, tert-dodecyl sulfide, etc.; in the field of special chemicals, it can be used as a raw material for oilfield drilling fluids, plasticizers, wax rheology aids, etc. In recent years, the demand for α-olefins has been increasing year by year. It is expected that the average annual growth rate of global α-olefins in the next five years will be 5%. Especially in China, the production of α-olefins is basically blank, and a large amount of such products need to be imported. Currently, the main production process of α-olefins is the ethylene oligomerization method, and a small amount of products are produced by the natural oil method.

[0003] Fatty aldehydes generally exist in natural plants and have a small content in nature. Fatty aldehydes have special fragrances or properties and can be used as raw materials for food flavors, cosmetic fragrances, special pharmaceutical intermediates, etc.

[0004] The technical routes for synthesizing fatty aldehydes include crotonaldehyde dehydrogenation to octanal (CN114573436B), oleic acid oxidation to nonanal (CN111013646B), decenal dehydrogenation to decanal (CN112794797B), etc.

[0005] In the prior art, for the catalyst for synthesizing α-olefins from fatty alcohols, the target product is a single α-olefin (such as patents CN 103333038 B and CN 105400540 B).

[0006] The reaction pathways for fatty alcohol dehydration and dehydrogenation to produce α-olefins and fatty aldehydes are as follows: (1) fatty alcohol dehydration to produce α-olefins, (2) fatty alcohol dehydrogenation to produce fatty aldehydes. The specific reaction formulas are as follows: .

[0007] If α-olefins and fatty aldehydes are used as the target products synthesized from fatty alcohols at the same time, the ratio of the two products can be flexibly adjusted according to market demand, enabling the same reaction device and catalyst to have the function of producing two high-value-added products. There is no catalyst in the prior art for simultaneously synthesizing α-olefins and fatty aldehydes.

[0008] In view of this, the present invention is specifically proposed. Summary of the Invention

[0009] The object of the present invention is to provide a catalyst for synthesizing α-olefins and co-producing fatty aldehydes, and its preparation method and application, so as to solve the above problems.

[0010] To achieve the above object, the present invention specifically adopts the following technical solutions: The first technical solution is a catalyst for synthesizing α-olefins and co-producing fatty aldehydes, which includes a dehydrogenation active site, a dehydration active site, a dispersion aid, and a carrier; the dispersion degree of the dehydrogenation active site is greater than 31.0%; the concentration of the dehydration active site is 4.5 - 9.0 μmol / g.

[0011] The present invention preferably has the dispersion degree of the dehydrogenation active site greater than 31.0%. If it is lower than this value, the distribution of the active metal is uneven and agglomeration occurs, resulting in a decrease in the dehydrogenation performance of the catalyst; the concentration of the dehydration active site is between 4.5 - 9.0 μmol / g. If it is lower than this ratio, the dehydration activity of the catalyst is insufficient, and if it is higher than this ratio, the generated α-olefins will isomerize to form internal olefins.

[0012] Optionally, the dehydrogenation active site is provided by a transition metal, the dehydration active site is provided by an active oxide, and the dispersion aid is a metal oxide. That is, the catalyst includes a transition metal, an active oxide, a dispersion aid, and a carrier.

[0013] Further, the transition metal is one or more of Cu, Zn, Cr, etc.; the active oxide is TiO2 and / or Al2O3; the dispersion aid is CeO2 and / or Y2O3; the carrier is diatomite, silica, or molecular sieve.

[0014] Metals such as Cu, Zn, Cr, etc. have excellent alcohol dehydrogenation functions; the role of TiO2 or Al2O3 is to form an active oxide, making the catalyst have excellent hydroxyl dehydration functions; the role of CeO2 or Y2O3 is to form a dispersion aid, which can improve the dispersion of the active components on the carrier, making the catalyst have high-efficiency fatty alcohol dehydrogenation and dehydration functions.

[0015] Optionally, by weight, in the catalyst, the proportion of the transition metal is 0.8 - 3.6 wt%, the proportion of the active oxide is 6.1 - 10.8 wt%, the proportion of the dispersion aid is 0.5 - 2.3 wt%, and the proportion of the carrier is 86.4 - 91.0 wt%.

[0016] The second technical solution is a preparation method of the catalyst for synthesizing α-olefins and co-producing fatty aldehydes, including the following steps: S1: Add polyacrylamide and the carrier into the aqueous solution of the transition metal compound at the same time. After precipitation, filter and collect the precipitate, wash it, first stand, first dry, and freeze to obtain Sample 1.

[0017] Specifically, a transition metal compound is added to deionized water to form an aqueous solution. Polyacrylamide and a carrier are simultaneously added to the aqueous solution of the transition metal compound. Using the carrier as the nucleation center, polyacrylamide and the transition metal compound are co-deposited on the surface of the carrier to form a precipitate. The purpose of using polyacrylamide is that the nitrogen-containing functional groups of polyacrylamide can complex with the transition metal compound and precipitate it uniformly on the surface of the carrier, constructing dehydrogenation active sites and providing conditions for the introduction of subsequent dehydration active sites.

[0018] Further, the transition metal compound is one or several of copper nitrate, zinc nitrate or chromium nitrate in any proportion mixture.

[0019] Preferably, the mass ratio of the transition metal compound to polyacrylamide is (0.45 - 1.12):(0.30 - 0.76), which is beneficial to the full complexation and precipitation of the transition metal and the organic matter. Otherwise, the complexation is incomplete and it cannot be evenly dispersed on the surface of the carrier.

[0020] Preferably, the mass ratio of the transition metal compound to the carrier is (0.45 - 1.12):(10 - 12).

[0021] Preferably, the first standing is carried out at room temperature for 2 - 5 h.

[0022] Preferably, the first drying is multiple drying; more preferably, the multiple drying is drying at 30 - 60 °C for 2 - 5 h and drying at 100 - 120 °C for 6 - 12 h.

[0023] Preferably, the freezing temperature is -25 °C or below.

[0024] S2: An active oxide precursor compound and a dispersion aid are added to water to obtain an aqueous solution, and then it is impregnated on the sample one in an equal volume manner. After the second standing and the second drying, sample two is obtained.

[0025] Preferably, the aqueous solution before impregnation is heated to 40 - 60 °C, and then it is impregnated on sample one in an equal volume manner, which can greatly reduce the stacking and covering probability between the dehydrogenation active sites and the dehydration active sites, so that the dehydrogenation active sites and the dehydration active sites are organically matched to achieve the best catalytic effect.

[0026] In the present invention, the two methods of introducing a dispersion aid and freeze impregnation are used simultaneously to enable the two active components to be highly dispersed and reasonably matched, and play their roles simultaneously to efficiently synthesize α-olefins and fatty aldehydes.

[0027] Preferably, the dosage of the active oxide precursor compound is 0.93 - 6.82 times that of the transition metal compound; further, the dosage of the dispersion aid is 0.28 - 0.88 times that of the transition metal compound; furthermore, the mass ratio of the active oxide precursor compound, the dispersion aid and water is (1.10 - 7.63):(0.19 - 0.99):(8 - 15).

[0028] If the dosage of the active oxide is too low, there will be insufficient dehydration active sites, and the catalyst cannot achieve effective hydroxyl dehydration reaction activity. If the dosage of the active oxide is too high, there will be an excess of dehydration active sites, resulting in the further isomerization of α-olefins into internal olefin by-products. If the dosage of the dispersion aid is too low, the dispersibility of the dehydrogenation and dehydration active components will be insufficient, and the conversion rate of fatty alcohols will decrease. If the dosage of the dispersion aid is too high, it will occupy too much of the carrier surface, leading to a decrease in the selectivity of α-olefins and fatty aldehydes.

[0029] Preferably, the second standing is carried out at room temperature for 2 - 5 h.

[0030] Preferably, the second drying is multiple drying; more preferably, the multiple drying is drying at 30 - 60 °C for 2 - 5 h and drying at 100 - 120 °C for 6 - 12 h.

[0031] The multiple drying conditions are the optimal conditions. Single drying or outside this range will cause uneven distribution of active components during drying and cracking of the catalyst, affecting the effect of subsequent preparation conditions and even the performance of the catalyst.

[0032] S3: The sample two is heated and reduced in an H2 atmosphere, and then after cooling to room temperature in an H2 atmosphere, it is passivated with oxygen-deficient air to obtain the product.

[0033] Preferably, the heating and reduction in an H2 atmosphere is as follows: heating to 300 - 500 °C at a rate of 0.5 - 2.0 °C / min, and the reduction time is 4 - 6 h; the H2 space velocity is 400 - 700 h -1 .

[0034] Preferably, the passivation with oxygen-deficient air is as follows: passivating with oxygen-deficient air with an O2 content of 0.5 - 2.0% for 3 - 5 h.

[0035] The present invention uses the method of embedding nitrogen-containing organic substances to complex and co-precipitate metals such as Cu, Cr, Zn and organic substances, so as to achieve a high degree of dispersion of dehydrogenation active sites, creating a basic condition for the organic matching of dehydrogenation active sites and subsequently introduced dehydration active sites; using the method of freeze impregnation, introducing dehydration active sites such as TiO2 and Al2O3 onto the dehydrogenation catalyst, and at the same time making the dehydrogenation and dehydration active sites highly dispersed and organically matched through aids such as CeO2 and Y2O3, so that the catalyst has both alcohol dehydrogenation performance and hydroxyl catalytic dehydration function.

[0036] The present invention also provides an application of the catalyst for co-producing α-olefins and fatty aldehydes, which uses fatty alcohols as raw materials and synthesizes α-olefins and fatty aldehydes under the action of the catalyst.

[0037] Further, the specific application method is to place the catalyst in a fixed-bed reactor, under a pressure of 0.1 - 0.4 MPa, heat it to the reaction temperature of 220 - 320 °C at a rate of 0.5 - 2.0 °C / min, and feed the fatty alcohols at a space velocity of 0.1 - 1.0 h -1 for reaction.

[0038] In the fixed-bed reactor, the above reaction conditions can effectively exert the performance of the catalyst, reasonably match the alcohol dehydrogenation performance and hydroxyl dehydration performance of the catalyst, and make the ratio of the generated α-olefins and fatty aldehydes adjustable. In the reaction temperature range of 220 - 320 °C, with the increase of the reaction temperature, the yield of fatty aldehydes decreases, and the yield of α-olefins increases, and the yield ratio of the two is (8.47 - 1.35) : (98.65 - 91.53).

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows: The catalyst of the present invention realizes the purposes of dehydrogenation and dehydration by simultaneously introducing dehydrogenation active sites and dehydration active sites and controlling the dispersion degree of dehydrogenation active sites and the concentration of dehydration active sites.

[0040] The present invention creatively uses transition metals for the dehydrogenation and dehydration of fatty alcohols to produce fatty aldehydes and α-olefins. By introducing transition metals such as Cu, Zn, Cr, etc., dehydrogenation active sites are provided. By introducing active oxides such as TiO2, Al2O3, etc., the surface acidity of the catalyst is adjusted and dehydration active sites are provided. By introducing dispersion aids such as CeO2, Y2O3, the synergistic effect of each component of the catalyst is promoted, and the dosage of various components is controlled, so that the two types of dehydrogenation and dehydration active sites can play their roles simultaneously.

[0041] The catalyst preparation method of the present invention uses the coprecipitation method of transition metal salts and polyacrylamide to deposit transition metals and organic carbon and nitrogen compounds on the carrier, so that the nitrogen-containing functional groups are complexed with transition metal compounds, thereby promoting the dispersion of active components; by freeze impregnation, the stacking and covering of active components are inhibited, and the active site precursors are immobilized on the catalyst by the method of freeze impregnation combined with dispersion aids, improving the synergistic effect of each active component, and making the catalyst have the bifunctional characteristics of synthesizing two products.

[0042] The synergistic effect of the transition metal, active oxide and dispersion aid in the catalyst of the present invention enables the catalyst to have both the dehydration and dehydrogenation functions of fatty alcohols, generating α-olefins and fatty aldehydes. By this method, the ratio of α-olefin and fatty aldehyde products can be adjusted according to operating parameters. On the premise of realizing the co-production of two products, the total product yield is greater than 93.0%. Detailed implementation mode

[0043] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0044] Example 1 Prepare a catalyst according to the preparation method provided by the present invention. The specific steps are as follows: Weigh 0.70 g of zinc nitrate and add it to 100 ml of deionized water. Add 0.47 g of polyacrylamide and 11 g of carrier molecular sieve to the solution at the same time. Filter and wash the obtained precipitate, place it at room temperature for 2 h, dry it at 50 °C for 4 h, dry it at 100 °C for 9 h, and freeze it below -25 °C to obtain Sample 1.

[0045] Add 1.83 g of titanyl sulfate and 0.19 g of cerium nitrate to 15 ml of deionized water. Heat the obtained solution to 40 °C and impregnate it on Sample 1 in an equal volume. Place it at room temperature for 4 h, dry it at 50 °C for 3 h, and dry it at 120 °C for 9 h to obtain Sample 2.

[0046] Heat Sample 2 to 300 °C at a rate of 0.5 °C / min in an H2 atmosphere and reduce it at this temperature for 5 h. The H2 space velocity is 600 h -1 . After the reduced sample is cooled to room temperature in an H2 atmosphere, passivate it with lean oxygen air with an O2 content of 0.5% for 4 h to obtain the catalyst for synthesizing α-olefins and co-producing fatty aldehydes.

[0047] The obtained catalyst has a zinc metal percentage content of 1.2 wt%, a titanium dioxide percentage content of 10.8 wt%, a cerium oxide percentage content of 0.5 wt%, a carrier molecular sieve percentage content of 87.5 wt%, a zinc dehydrogenation active site dispersion degree of 33.2%, and a dehydration active site concentration of 4.5 μmol / g.

[0048] Load 2 mL of the above catalyst into a fixed-bed tubular reactor. Raise the temperature of the catalyst to 220 °C at a pressure of 0.1 MPa at a rate of 2.0 °C / min, and use a fatty alcohol volume space velocity of 1.0 h -1 for the dehydration dehydrogenation reaction. The reaction results are listed in Table 1.

[0049] Example 2 Weigh 1.12 g of copper nitrate and add it to 100 ml of deionized water. Add 0.76 g of polyacrylamide and 12 g of carrier diatomaceous earth to the solution simultaneously. Filter and wash the resulting precipitate, let it stand at room temperature for 3 h, dry it at 40 °C for 2 h, dry it at 120 °C for 10 h, and freeze it below -25 °C to obtain Sample 1.

[0050] Add 7.63 g of aluminum nitrate and 0.99 g of cerium nitrate to 8 ml of deionized water. Heat the resulting solution to 50 °C, impregnate it on Sample 1 in an equal volume, let it stand at room temperature for 4 h, dry it at 30 °C for 4 h, and dry it at 110 °C for 6 h to obtain Sample 2.

[0051] Heat Sample 2 to 400 °C at a rate of 1.0 °C / min in a H2 atmosphere and reduce it at this temperature for 6 h. The H2 space velocity is 700 h -1 . After the sample is cooled to room temperature in a H2 atmosphere, passivate it with lean oxygen air with an O2 content of 1.0% for 5 h to obtain the catalyst for synthesizing α-olefins and co-producing fatty aldehydes.

[0052] The obtained catalyst contains 1.8 wt% of metallic copper, 9.5 wt% of aluminum oxide, 2.3 wt% of cerium oxide, 86.4 wt% of carrier diatomaceous earth, the dispersion degree of copper dehydrogenation active sites is 35.5%, and the concentration of dehydration active sites is 5.9 μmol / g.

[0053] Load 2 mL of the above catalyst into a fixed-bed tubular reactor. Heat the catalyst from 0.2 MPa to 260 °C at a rate of 1.0 °C / min, and use a fatty alcohol volume space velocity of 0.8 h -1 to carry out the dehydration and dehydrogenation reaction. The reaction results are listed in Table 1.

[0054] Example 3 Weigh 0.67 g of chromium nitrate and add it to 100 ml of deionized water. Add 0.45 g of polyacrylamide and 10 g of silica to the solution simultaneously. Filter and wash the resulting precipitate, let it stand at room temperature for 4 h, dry it at 30 °C for 2 h, dry it at 100 °C for 8 h, and freeze it below -25 °C to obtain Sample 1.

[0055] Add 1.10 g of titanium oxysulfate and 0.24 g of yttrium nitrate to 9 ml of deionized water. Heat the resulting solution to 60 °C, impregnate it on Sample 1 in an equal volume, let it stand at room temperature for 5 h, dry it at 40 °C for 2 h, and dry it at 100 °C for 7 h to obtain Sample 2.

[0056] Heat Sample 2 to 500 °C at a rate of 0.5 °C / min in a H2 atmosphere and reduce it at this temperature for 4 h. The H2 space velocity is 500 h -1After the sample was cooled to room temperature in an H2 atmosphere, it was passivated with lean oxygen air with an O2 content of 1.5% for 3 h to obtain the catalyst for synthesizing α-olefins and co-producing fatty aldehydes.

[0057] The obtained catalyst had a metal chromium content of 3.6 wt%, a titanium dioxide content of 7.2 wt%, a yttrium oxide content of 0.8 wt%, and a carrier silica content of 88.4 wt%. The dispersion degree of chromium dehydrogenation active sites was 39.4%, and the dehydration active site concentration was 9.0 μmol / g.

[0058] 2 mL of the above catalyst was loaded into a fixed-bed tubular reactor. The catalyst was heated to 300 °C at a rate of 1.5 °C / min under a pressure of 0.3 MPa, with a fatty alcohol volume space velocity of 0.6 h -1 for the dehydration and dehydrogenation reaction. The reaction results are listed in Table 1.

[0059] Example 4 Weigh 0.45 g of zinc nitrate and add it to 100 ml of deionized water. Add 0.30 g of polyacrylamide and 11 g of molecular sieve to the solution at the same time. The obtained precipitate was filtered and washed, placed at room temperature for 5 h, dried at 60 °C for 3 h, dried at 110 °C for 12 h, and frozen below -25 °C to obtain Sample 1.

[0060] Add 4.83 g of aluminum nitrate and 0.49 g of cerium nitrate to 10 ml of deionized water. Heat the obtained solution to 40 °C and impregnate it on Sample 1 in an equal volume. Place it at room temperature for 2 h, dry it at 60 °C for 5 h, and dry it at 100 °C for 10 h to obtain Sample 2.

[0061] Heat Sample 2 to 450 °C at a rate of 2.0 °C / min in an H2 atmosphere and reduce it at this temperature for 5 h. The H2 space velocity is 500 h -1 After the sample was cooled to room temperature in an H2 atmosphere, it was passivated with lean oxygen air with an O2 content of 2.0% for 4 h to obtain the catalyst for synthesizing α-olefins and co-producing fatty aldehydes.

[0062] The obtained catalyst had a metal zinc content of 0.8 wt%, an aluminum oxide content of 6.9 wt%, a cerium oxide content of 1.3 wt%, and a carrier molecular sieve content of 91.0 wt%. The dispersion degree of zinc dehydrogenation active sites was 36.0%, and the dehydration active site concentration was 6.9 μmol / g.

[0063] 2 mL of the above catalyst was loaded into a fixed-bed tubular reactor. The catalyst was heated to 320 °C at a rate of 0.5 °C / min under a pressure of 0.4 MPa, with a fatty alcohol volume space velocity of 0.4 h -1 for the dehydration and dehydrogenation reaction. The reaction results are listed in Table 1.

[0064] Example 5 Weigh 0.69 g of copper nitrate and 0.43 g of chromium nitrate and add them to 100 ml of deionized water. Then add 0.50 g of polyacrylamide and 12 g of diatomite to the solution simultaneously. Filter and wash the obtained precipitate, place it at room temperature for 5 h, dry it at 40 °C for 5 h, dry it at 100 °C for 6 h, and freeze it below -25 °C to obtain Sample 1.

[0065] Add 1.10 g of titanium oxysulfate and 0.63 g of yttrium nitrate to 12 ml of deionized water. Heat the obtained solution to 50 °C, impregnate it on Sample 1 in an equal volume, place it at room temperature for 3 h, dry it at 50 °C for 2 h, and dry it at 110 °C for 12 h to obtain Sample 2.

[0066] Heat Sample 2 to 550 °C at a rate of 1.5 °C / min in a H₂ atmosphere, reduce it at this temperature for 6 h, and the H₂ space velocity is 400 h -1 . After the sample is cooled to room temperature in a H₂ atmosphere, passivate it with lean oxygen air with an O₂ content of 1.0% for 4 h to obtain the catalyst for synthesizing α-olefins and co-producing fatty aldehydes.

[0067] The obtained catalyst has a metal copper percentage content of 1.2 wt%, a metal chromium percentage content of 2.1 wt%, a titanium dioxide percentage content of 6.1 wt%, a yttrium oxide percentage content of 1.8 wt%, a carrier diatomite percentage content of 88.9 wt%, a dispersion degree of copper dehydrogenation active sites of 31.0%, a dispersion degree of chromium dehydrogenation active sites of 32.9%, and a dehydration active site concentration of 8.1 μmol / g.

[0068] Load 2 mL of the above catalyst into a fixed-bed tubular reactor. Raise the temperature of the catalyst to 280 °C at a rate of 2.0 °C / min under a pressure of 0.1 MPa, and use a fatty alcohol volume space velocity of 0.1 h -1 to carry out the dehydration dehydrogenation reaction. The reaction results are listed in Table 1.

[0069] Comparative Example 1 It is basically the same as Example 1, except that the addition amount of zinc nitrate in the preparation process is 0.40 g.

[0070] The obtained catalyst has a metal zinc percentage content of 0.9 wt%, a titanium dioxide percentage content of 10.8 wt%, a cerium oxide percentage content of 0.5 wt%, a carrier molecular sieve percentage content of 87.8 wt%, a dispersion degree of zinc dehydrogenation active sites of 26.0%, and a dehydration active site concentration of 2.8 μmol / g.

[0071] Load 2 mL of the above catalyst into a fixed-bed tubular reactor. Raise the temperature of the catalyst to 220 °C at a rate of 2.0 °C / min under a pressure of 0.1 MPa, and use a fatty alcohol volume space velocity of 1.0 h -1 to carry out the dehydration dehydrogenation reaction. The reaction results are listed in Table 1.

[0072] Comparative Example 2 It is basically the same as Example 2, except that the amount of cerium nitrate added during the preparation process is 1.20 g.

[0073] The obtained catalyst contains 1.8 wt% of metallic copper, 9.5 wt% of aluminum oxide, 2.7 wt% of cerium oxide, and 86.0 wt% of the carrier diatomite. The dispersion degree of copper dehydrogenation active sites is 21.2%, and the concentration of dehydration active sites is 3.6 μmol / g.

[0074] Load 2 mL of the above catalyst into a fixed-bed tubular reactor. Heat the catalyst from room temperature to 260 °C at a rate of 1.0 °C / min under a pressure of 0.2 MPa, and use a space velocity of 0.8 h -1 for the dehydration and dehydrogenation reaction. The reaction results are listed in Table 1.

[0075] Comparative Example 3 It is basically the same as Example 3, except that no freezing is carried out during the preparation of Sample 1.

[0076] The obtained catalyst contains 3.6 wt% of metallic chromium, 7.2 wt% of titanium dioxide, 0.8 wt% of yttrium oxide, and 88.4 wt% of the carrier silica. The dispersion degree of chromium is 8.0%, and the concentration of dehydration active sites is 2.3 μmol / g.

[0077] Load 2 mL of the above catalyst into a fixed-bed tubular reactor. Heat the catalyst from room temperature to 300 °C at a rate of 1.5 °C / min under a pressure of 0.3 MPa, and use a space velocity of 0.6 h -1 for the dehydration and dehydrogenation reaction. The reaction results are listed in Table 1.

[0078] Comparative Example 4 It is basically the same as Example 3, except that cerium nitrate is not added during the preparation of Sample 2.

[0079] The obtained catalyst contains 0.81 wt% of metallic zinc, 7.0 wt% of aluminum oxide, and 92.19 wt% of the carrier molecular sieve. The dispersion degree of zinc is 12.3%, the dispersion degree of copper is 6.2%, and the concentration of dehydration active sites is 3.1 μmol / g.

[0080] Load 2 mL of the above catalyst into a fixed-bed tubular reactor. Heat the catalyst from room temperature to 320 °C at a rate of 0.5 °C / min under a pressure of 0.4 MPa, and use a space velocity of 0.4 h -1 for the dehydration and dehydrogenation reaction. The reaction results are listed in Table 1.

[0081] Table 1 Reaction results of the catalysts obtained in Examples 1-5 and Comparative Examples 1-4 for the dehydration and dehydrogenation of fatty alcohols to synthesize α-olefins and fatty aldehydes 。

[0082] As can be seen from Table 1, when the catalysts of Examples 1-5 participated in the synthesis reaction, the ratio of the products α-olefins and fatty aldehydes could be adjusted, and the total yield was greater than 93.0%, enabling the co-production of the two products. From the results of Comparative Examples 1-4, it can be seen that without the synergistic effect of the active oxide, the promoter, and the dehydrogenation active metal in the catalyst, or without key catalyst preparation steps such as freeze impregnation, the product yield of the synthesis reaction decreased significantly.

[0083] As can be seen from the examples, according to the preferred technical means of the present invention, heating the solution before impregnation and then impregnating it onto Sample 1 that has been frozen can greatly reduce the stacking and covering probability between the dehydrogenation active sites and the dehydration active sites, significantly improving the yields of α-olefins and fatty aldehydes respectively.

[0084] Please note that the technical features of the above examples can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above examples are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification. The above examples only represent several implementation modes of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of the patent of this application shall be subject to the appended claims.

Claims

1. A catalyst for synthesizing α-olefins and producing fatty aldehydes, characterized in that: It includes dehydrogenation active sites, dehydration active sites, dispersing aids and carriers; The dehydrogenation active site dispersion is greater than 31.0%; the dehydration active site concentration is 4.5-9.0 μmol / g.

2. The catalyst according to claim 1, characterized in that The dehydrogenation active sites are provided by transition metals, the dehydration active sites are provided by active oxides, and the dispersing aid is a metal oxide.

3. The catalyst according to claim 2, characterized in that The transition metal is any one or more of Cu, Zn and Cr; the active oxide is TiO2 and / or Al2O3; the dispersing aid is CeO2 and / or Y2O3; and the carrier is diatomaceous earth, silicon dioxide or molecular sieve.

4. The catalyst according to claim 2 or 3, characterized in that According to weight ratio, in the catalyst, the transition metal accounts for 0.8-3.6wt%, the active oxide accounts for 6.1-10.8wt%, the dispersing aid accounts for 0.5-2.3wt%, and the carrier accounts for 86.4-91.0wt%.

5. The method for preparing the catalyst for synthesizing α-olefins and co-producing fatty aldehydes according to any one of claims 1 to 4, characterized in that: The steps include: S1: adding polyacrylamide and a carrier simultaneously to an aqueous solution of a transition metal compound, collecting the precipitate by filtration after precipitation, washing, first standing, first drying, and freezing to obtain a sample 1; S2: adding the active oxide precursor compound and the dispersing aid into water to obtain an aqueous solution, and impregnating the sample 1 with an equal volume, and performing a second standing and a second drying to obtain a sample 2; S3: reducing the sample 2 by heating in a H2 atmosphere, and then passivating it with oxygen-deficient air after the H2 atmosphere drops to room temperature.

6. The preparation method according to claim 5, characterized in that: The step S1 satisfies one or more of the following conditions: a. The transition metal compound is one or a mixture of copper nitrate, zinc nitrate or chromium nitrate in any proportion; b. The mass ratio of the transition metal compound to polyacrylamide is (0.45-1.12): (0.30-0.76); c. The mass ratio of the transition metal compound to the carrier is (0.45-1.12):(10-12); d. The first standing is carried out at room temperature for 2-5 hours; e. the first drying is multiple drying; f. The multiple drying is drying at 30-60°C for 2-5 hours and drying at 100-120°C for 6-12 hours; g. The freezing temperature is -25°C or below.

7. The preparation method according to claim 5 or 6, characterized in that: The step S2 satisfies one or more of the following conditions: a. before the immersion, the aqueous solution is heated to 40-60°C; b. The amount of the active oxide precursor compound is 0.93-6.82 times that of the transition metal compound; c. The amount of the dispersing agent is 0.28-0.88 times that of the transition metal compound; d. The mass ratio of the active oxide precursor compound, the dispersing aid and water is (1.10-7.63): (0.19-0.99): (8-15); e. The second standing is carried out at room temperature for 2-5 hours; f. The second drying is multiple drying; g. The multiple drying is drying at 30-60°C for 2-5 hours and drying at 100-120°C for 6-12 hours.

8. The preparation method according to claim 5, characterized in that: The step S3 satisfies one or more of the following conditions: a. The temperature reduction under H2 atmosphere is: heating to 300-500℃ at a rate of 0.5-2.0℃ / min, and the reduction time is 4-6h; the H2 space velocity is 400-700h -1 ; b. The passivation with oxygen-depleted air is: passivation with oxygen-depleted air having an O2 content of 0.5-2.0% for 3-5 hours.

9. Use of the catalyst for synthesizing α-olefins and co-producing fatty aldehydes according to any one of claims 1 to 4, characterized in that: The alpha-olefin and the fatty aldehyde are synthesized by taking the fatty alcohol as the raw material under the action of the catalyst.

10. The use according to claim 9, characterized in that: The application method is to place the catalyst in a fixed bed reactor, heat it to a reaction temperature of 220-320°C at a rate of 0.5-2.0°C / min under a pressure of 0.1-0.4 MPa, and heat the fatty alcohol at a space velocity of 0.1-1.0h -1 Feed the reaction.