Catalyst, preparation method thereof and selective hydrogenation method

Abstract

The invention relates to a catalyst, a preparation method thereof and a selective hydrogenation method. Specifically, the invention relates to a method for preparing 1, 4-butanediol. The process can include reacting a solution comprising 1, 4-butynediol with hydrogen in the presence of a catalyst. The catalyst may comprise cerium.

Description

[0001] This application is a divisional application. The application date of the parent application is August 6, 2019, the application number is 201980049535.9, and the name of the invention is “Catalyst, preparation method thereof and selective hydrogenation method”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 62 / 715,926, filed on August 8, 2018, entitled “CATALYSTS, PREPARATION METHOD THEREOF, AND SELECTIVE HYDROGENATION PROCESSES,” the disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to a catalyst, and more particularly to a catalyst for preparing 1,4-butanediol, a preparation method thereof, and a selective hydrogenation method using the catalyst. Background Art

[0004] Framework metallic nickel in the form of a granular fixed bed is generally used industrially for the preparation of butanediol (BDO), a component for the preparation of polyesters, from the unsaturated compound 1,4-butynediol (BYD).

[0005] US 6,262,317 discloses a method for preparing 1,4-butanediol by continuous catalytic hydrogenation of 1,4-butynediol. The method includes reacting 1,4-butynediol with hydrogen in a liquid continuous phase in the presence of a heterogeneous hydrogenation catalyst. The catalyst generally comprises one or more elements of transition groups I, VI, VII and VIII of the periodic table. The catalyst preferably also comprises at least one element as a promoter for increasing activity, the at least one element being selected from elements of main groups II, III, IV and VI of the periodic table, elements of transition groups II, III, IV and V, and lanthanides. The promoter content of the catalyst is generally up to 5% by weight. The catalyst may be a precipitated, supported or skeleton catalyst.

[0006] CN 201210212109.2 discloses a method for preparing and activating a skeleton metal nickel-aluminum-X catalyst, wherein the catalyst is specifically used for preparing 1,4-butanediol by hydrogenation of 1,4-butynediol. X represents Mg, B, Sr, Cr, S, Ti, La, Sn, W, Mo or Fe.

[0007] Current catalysts generally have a predictable limited lifespan. Current methods produce n-butanol and other byproducts at a gradually increasing rate until the maximum specification limit is reached, which defines the end point of the bed catalyst service life. Acidic Al substances present in skeleton metal catalysts such as hydrated alumina residues from leaching processes are considered to be a major cause of the production of byproducts including butanol. Skeleton metal catalysts generally may contain a small amount of added elements as promoters, the functions of which include improving the activity, selectivity and stability of the catalyst in the chemical environment of a given hydrogenation process. Some promoters for skeleton metals such as conventional Mo, Cr or Fe may actually increase the formation of butanol byproducts due to increased surface acidity. Operating conditions such as relatively low temperature, relatively high pressure and control of feed pH have been previously optimized, and their combination still cannot fully inhibit the formation of butanol. It is desirable to develop a method for preparing butanediol while minimizing and / or delaying the formation of n-butanol and other byproducts. Butanediol is the main component for preparing polyester. Since downstream uses have impurity restrictions on butanediol, reducing contaminants in butanediol during the process of making butanediol can significantly reduce costs, for example, costs associated with later separating (eg, distilling) impurities from butanediol. Summary of the invention

[0008] The present invention provides a method for preparing 1,4-butanediol from a 1,4-butynediol solution in the presence of a catalyst comprising cerium.The method for preparing 1,4-butanediol unexpectedly produces significantly lower amounts of butanol as a major by-product.

[0009] Thus, one example of the present invention is a method for preparing 1,4-butanediol. The method may include reacting a solution comprising 1,4-butynediol with hydrogen in the presence of a catalyst, the catalyst comprising cerium as a promoter.

[0010] Another example of the present invention is a catalyst for preparing 1,4-butanediol. The catalyst may be a skeleton metal catalyst comprising cerium as a promoter.

[0011] Another example of the present invention is a method for preparing a catalyst. The method may include melting and mixing cerium oxide, a first element, and a second element to form an alloy, and then activating the alloy using an alkaline solution to form a catalyst. The first element may be Ni, and the second element may be aluminum. DETAILED DESCRIPTION

[0012] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the present invention is described with reference to the embodiments of the present invention.

[0013] A numerical value modified with "about" herein means that the numerical value can vary by 10%. A numerical range modified with "about" herein means that the upper and lower limits of the numerical range can vary by 10%.

[0014] One example of the present invention is a method for preparing 1,4-butanediol. The method may include reacting a solution containing 1,4-butynediol with hydrogen in the presence of a catalyst, the catalyst containing cerium as a promoter.

[0015] The solution containing 1,4-butynediol can be industrial grade 1,4-butynediol in the form of an aqueous solution, and can also contain components from the synthesis of butynediol as insoluble or soluble components, such as copper, bismuth, aluminum or silicon compounds. The main solvent of the solution containing 1,4-butynediol is generally water. The solution containing 1,4-butynediol can also contain other solvents, such as methanol, ethanol, propanol, butanol or 1,4-butanediol. The 1,4-butynediol in the solution is generally 10% to 90% by weight of the solution, preferably 20% to 80% by weight, and specifically preferably 30% to 70% by weight. In one embodiment, the solution containing 1,4-butynediol is 100% pure butynediol.

[0016] The solution including 1,4-butynediol may have a pH in the range of about 6.0 to about 11.0, preferably about 9 to about 10.

[0017] The hydrogen required for the reaction is preferably used in pure form. But it may also contain other components, such as methane and carbon monoxide. The hydrogen pressure applied to the fixed bed reactor for the method may be in the range of about 15MPa to about 30MPa. The inlet temperature of the fixed bed reactor may be in the range of about 80°C to about 120°C. The flow rate of the feed solution may be selected by those skilled in the art to allow the desired butynediol conversion level. The desired butynediol conversion level then depends on whether the process stream is partially recycled to the reactor inlet. With respect to non-recycled process streams, the desired conversion level in a "single pass" is usually very high, i.e., more than 99% by weight based on organic compounds.

[0018] According to the present invention, the catalyst used is those capable of hydrogenating C≡C triple bonds and double bonds into single bonds. The catalyst can be in the form of a fixed bed, a slurry or a suspension, or a combination thereof. In one embodiment, the catalyst is in the form of a fixed bed, and may have a particle size in the range of about 1 mm to about 8 mm, preferably about 2 mm to about 5 mm. In another embodiment, the catalyst is in the form of a slurry or a suspension, and may have a median particle size in the range of about 10 μm to about 100 μm, preferably about 20 μm to about 80 μm.

[0019] The catalyst may also include at least a first element selected from Ni, Co, Cu, Fe, and mixtures thereof. In one embodiment, the first element is Ni. The catalyst may also include at least a second element selected from aluminum, molybdenum, chromium, iron, copper, tin, zirconium, zinc, titanium, vanadium, and mixtures thereof. In one embodiment, the second element is aluminum.

[0020] The catalyst may be a skeletal metal catalyst. Suitable skeletal metal catalysts include skeletal metal nickel, skeletal metal copper, skeletal metal cobalt, skeletal metal nickel / molybdenum, skeletal metal nickel / copper, skeletal metal nickel / chromium, skeletal metal nickel / chromium / iron or rhenium sponge.

[0021] Cerium may be present in the catalyst in an amount ranging from about 1% to about 5%, preferably from about 1.5% to about 3.0%, by weight of the catalyst.

[0022] The molar ratio of hydrogen to butynediol in the reactor is at least 3:1, preferably 4:1 to 100:1.

[0023] When a fixed bed reactor is used in the method of the present invention, the space velocity of the solution and the gas flowing through the fixed bed of the catalyst is not limited. One of ordinary skill in the art can adjust the space velocity of the solution and the gas to obtain the best yield of 1,4-butanediol with a small amount of by-products such as butanol.

[0024] The catalyst according to the invention may comprise only one type of catalyst or a mixture of several types of catalysts. The mixture of several types of catalysts may be present as a pseudo-homogeneous mixture or as a structured bed, wherein the individual reaction zones are each constituted by a pseudo-homogeneous catalyst bed. It is also possible to combine the methods, for example using one catalyst type at the beginning of the reaction and a mixture further downstream.

[0025] The process may produce butanol as a byproduct in an amount in the range of less than about 3.0 wt%, preferably less than about 2.5 wt%, based on the total weight of butanol and 1,4-butanediol.

[0026] In one embodiment of the method for preparing 1,4-butanediol, the catalyst is a skeleton element catalyst. The catalyst comprises at least a first element, at least a second element and cerium, wherein the first element is selected from Ni, Co, Cu, Fe and mixtures thereof, and the second element is selected from aluminum, molybdenum, chromium, iron, copper, tin, zirconium, zinc, titanium, vanadium and mixtures thereof. Cerium is present in an amount ranging from about 1% by weight to about 5% by weight of the catalyst. The solution comprising 1,4-butynediol has a pH of about 9.0 to about 10.0. The method produces butanol as a byproduct, which is less than about 3.0% by weight based on the total weight of butanol and 1,4-butanediol.

[0027] Another example of the present invention is a catalyst for preparing 1,4-butanediol. The catalyst may include a skeleton metal catalyst that includes cerium as a promoter. Cerium is present in the catalyst in an amount ranging from about 1.0% to about 5.0% by weight of the catalyst, preferably from about 1.5% to about 3.0% by weight. In one embodiment comprising about 1.0% to about 5.0% by weight of cerium, the first element of the skeleton metal is nickel and the second element of the skeleton metal is aluminum.

[0028] Another example of the present invention is a method of preparing a catalyst. The method may include melting and mixing cerium oxide, a first element, and a second element to form an alloy. The alloy is then activated by contacting with an alkaline solution. In one embodiment, the alkaline solution is an aqueous solution of sodium hydroxide or potassium hydroxide having a concentration in the range of 1 wt % to 25 wt %.

[0029] The first element can be selected from Ni, Co, Cu, Fe and their mixture. The second element can be selected from aluminum, molybdenum, chromium, iron, copper, tin, zirconium, zinc, titanium, vanadium and their mixture. In one embodiment, the first element is Ni, and the second element is aluminum. Based on the total weight of the cerium oxide, Ni and aluminum, Ni can exist in an amount in the range of about 40 weight % to about 60 weight %. Based on the total weight of the cerium oxide, Ni and aluminum, aluminum can exist in an amount in the range of about 40 weight % to about 60 weight %. Based on the total weight of the cerium oxide, Ni and aluminum, cerium oxide can exist in an amount in the range of about 1 weight % to about 5 weight %, preferably about 1.5 weight % to about 3.5 weight %. During the melting and mixing process, cerium oxide can be converted into cerium in the alloy.

[0030] In one embodiment, the alkaline solution is continuously pumped through the alloy bed to activate the alloy. In another embodiment, the alloy particles are added to the alkaline solution in batches to activate the alloy. In one embodiment, the catalyst is a skeletal metal catalyst.

[0031] In one embodiment, the method for preparing the catalyst comprises melting and mixing cerium oxide, a first element and a second element to form an alloy, and contacting the alloy with an alkaline aqueous solution to produce a catalyst. The first element is selected from Ni, Co, Cu, Fe and mixtures thereof, and the second element is selected from aluminum, molybdenum, chromium, iron, copper, tin, zirconium, zinc, titanium, vanadium and mixtures thereof. Based on the gross weight of the cerium oxide, the first element and the second element, cerium oxide exists in an amount in the range of about 1 wt % to about 5 wt %. In an embodiment comprising about 1.0 wt % to about 5.0 wt % cerium, the first element of the skeleton metal is nickel, and the second element of the skeleton metal is aluminum.

[0032] Another example of the present invention is a catalyst produced by a method of preparing a catalyst according to one embodiment of the present invention.

[0033] Descriptions of various embodiments of the present invention have been given for purposes of illustration, but these descriptions are not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to best explain the principles of the embodiments, to improve upon practical applications or technologies existing in the marketplace, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

[0034] Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited to the following Examples. Example

[0035] Comparative Example 1: Unpromoted Nickel Catalyst Catalyst preparation.

[0036] An alloy is formed by melting and mixing the two components, the alloy comprising 58 wt% Al and 42 wt% Ni. The alloy is then crushed and sieved into alloy particles in the 8-12 mesh size range or in the range of about 2 mm to about 3 mm in diameter.

[0037] A portion of 390 g of alloy particles was placed in a beaker to form a "bed". The alloy particle bed was converted into a catalyst by contact with a "leaching agent", which consisted of five portions of an aqueous NaOH solution being pumped continuously through the alloy bed at a constant rate. Each portion of the aqueous NaOH solution was 18 liters, and the strength of the five portions increased during the process, starting with 0.9%, then 1.75%, 2.6%, 3.5%, and finally 4.35%. Each portion of the aqueous NaOH solution was delivered through the alloy bed in 40 minutes, while the process temperature was controlled at a target of 38°C using an immersion cooling coil (with internal water flow).

[0038] The catalyst was then washed with 2 liters of 0.25% NaOH solution for 10 minutes and then with water at 45°C until the outflowing wash water reached a pH of 9.

[0039] Catalytic testing The prepared catalyst was kept in a water-wet state when loaded into a vertical column reactor having an inner diameter of 0.5 inches and a height of about 6 inches. This corresponded to a catalyst bed volume of 18 mL.

[0040] The reactant feed solution was prepared by dissolving solid 2-butyne-1,4-diol at 35 wt% in water. As a variable to be tested for the effect on selectivity, the pH of the reactant feed solution was adjusted to 5.0 or 10.0 by adding a small amount of 15% NaOH solution.

[0041] The reaction conditions adopted were: inlet temperature of 100°C, peak temperature: 150°C (outlet temperature), hydrogen pressure = 2500 psig (17 MPa), and controllable range of liquid feed flow rate: 0.25-0.35 mL / min. A cocurrent upward flow of H2 gas and liquid was maintained (300 mL / min).

[0042] During the testing of this catalyst feed, the liquid feed flow rate was increased at various times and then allowed to remain at a constant level for several days. The feed source was switched between pH 10 and 5 as another independent variable. The sequence of pH and liquid flow rates of the reactant feed solutions employed is listed in Table 1.

[0043] The product assay was determined by GC analysis using a Restek Stabilwax 30×0.32×0.5 column, 90% ethanol solvent, diglyme as internal standard and a flame ionization detector, expressed as weight % of organic product. The yield for each condition reported in Table 1 is the average of samples taken after every 8 hours of continuous operation.

[0044] The main byproduct of interest, n-butanol ("BuOH"), ranged from 3.1% to 3.8% under various conditions for this standard baseline catalyst. Butanol yields were lower when higher pH feed solutions were used. The second byproduct (hydroxybutoxytetrahydrofuran, a cyclized acetal formed by reaction of product and feed molecules and dehydration) is listed in Table 1 as "acetal". Unconverted butynediol is referred to as "BYD" and the conversion % is based on the BYD residual content subtracted from 100%.

[0045] Comparative Example 2: La-Promoted Nickel Catalyst With respect to catalyst preparation, including alloy formation and activation, catalyst testing, and analysis of catalytic products in the BYD-BDO system, the procedure of Comparative Example 1 was followed. The alloy preparation used a mixture of 58 wt% Al, 2 wt% Ni, and 40 wt% of a 6% La-94% Ni binary alloy (American Elements). Bulk chemical analysis of the resulting three-component alloy by ICP yielded 2.6 wt% La. By similar analysis, the activated catalyst contained 2.9 wt% La.

[0046] The catalysts tested at each combination of BYD feed pH and liquid flow rate produced a significantly higher butanol range, ie, 5.8-6.2 wt %, as shown in Table 1.

[0047] Example 1: Ce-promoted nickel catalyst Regarding catalyst preparation, including alloy formation and activation, catalyst testing, and analysis of catalytic products in the BYD-BDO system, the procedure of Comparative Example 1 was followed. Compared with Comparative Example 1, the alloy preparation in Example 1 differs from the standard Ni-Al type in that cerium oxide CeO2 in particle form (0.5-1.0 mm diameter) is used, which is added to the alloy mixture at 1.6 wt % together with 57.8 wt % Al and 40.6 wt % Ni. The mixing and melting process converts CeO2 into Ce incorporated into the elemental alloy. X-ray diffraction of the resulting solid alloy indicates that there is no CeO2 raw material. Bulk chemical analysis of the alloy was performed by ICP, resulting in 1.3 wt % Ce. By similar analysis, after selective removal of Al, the activated catalyst contains 1.5 wt % Ce.

[0048] Application of the catalyst from a BYD feed solution at pH 10 produced a significantly lower butanol range, ie, 2.5 wt% - 3.2 wt%, depending on the flow rate, as shown in Table 1.

[0049] Example 2: Ce-promoted nickel catalyst (higher Ce content) With respect to catalyst preparation, including alloy formation and activation, catalyst testing, and analysis of catalytic products in the BYD-BDO system, the procedure of Comparative Example 1 was followed. The alloy was prepared according to the method of Example 1, but cerium oxide was added to the alloy mixture at 3.0 wt % along with 57.7 wt % Al and 39.3 wt % Ni. Bulk chemical analysis of the alloy by ICP yielded 1.9 wt % Ce. By similar analysis, the activated catalyst contained 2.9 wt % Ce.

[0050] Applying the catalyst in various combinations of BYD feed solution at pH 10 and different rates produced a lower butanol range of 2.1 wt% to 2.8 wt%, as shown in Table 1.

[0051] The effect of pH of the BYD feed solution was studied as follows: Three consecutive test stages were performed while still loading the above catalyst into the fixed bed reactor. In the three consecutive stages, the pH of the BYD feed solution was changed at 8, 9 and 11, respectively. Each stage lasted for about 5 days at a fixed feed flow rate of 0.30 cc / min. The BDO yield and by-product content are shown in Table 1. As shown in Example 2 of Table 1, the butanol by-product continues to decrease as the pH of the feed solution increases.

[0052] However, the acetal byproduct increased at pH 11 (to 1.2%), a trend that was observed at pH 10 (0.7%). The total content of combined butanol and acetal byproducts was lowest in the pH 9-10 range.

[0053] Example 3: Ce-promoted nickel catalyst Regarding alloy preparation, including alloy formation and activation, catalyst testing, and analysis of catalytic products in the BYD-BDO system, the procedure of Example 2 was followed. Bulk chemical analysis of the activated catalyst showed that the catalyst contained 2.1% Ce.

[0054] Similar to Comparative Example 2 using La promoter, the catalyst was applied from a feed solution of pH 10 and a relatively high flow rate of 0.4 mL / min, resulting in a butanol content of 3.4 wt %, as shown in Table 1.

[0055] These examples demonstrate the use of a cerium promoter to unexpectedly improve the selectivity of the process by significantly reducing the formation of butanol by-product.

[0056] The principles and embodiments of the present disclosure are set forth in the specification. The description of the embodiments of the present disclosure is only used to help understand the method of the present disclosure and its core concept. At the same time, for those of ordinary skill in the art, the present disclosure relates to the scope of the present disclosure, and the technical solution is not limited to a specific combination of technical features, and other technical solutions should also be covered, which are formed by combining technical features or equivalent features of technical features without departing from the concept of the present invention. For example, the technical solution can be obtained by (but not limited to) replacing the above-mentioned features disclosed in the present disclosure with similar features.

Claims

1. A method for preparing 1,4-butanediol, the method comprising: reacting a solution containing 1,4-butynediol with hydrogen in the presence of a catalyst, the catalyst consisting of a first element, a second element, and a promoter; wherein the promoter is cerium, the first element is Ni and the second element is aluminum; and wherein aluminum is present in an amount from greater than about 40 wt % to about 60 wt % of the catalyst.

2. The method according to claim 1, wherein the catalyst is in the form of a fixed bed, a suspension, or a combination thereof.

3. The process of claim 2, wherein the catalyst is in the form of the fixed bed and has a particle size ranging from about 1 mm to about 8 mm.

4. The method of claim 2, wherein the catalyst is in the form of the suspension and has a median particle size in the range of about 10 μm to about 100 μm.

5. The method of claim 1, wherein cerium is present in an amount ranging from about 1 wt% to about 5 wt% of the catalyst.

6. The method of claim 1, wherein cerium is present in an amount ranging from about 1.5 wt% to about 3.0 wt% of the catalyst.

7. The method of claim 1, wherein the solution comprising 1,4-butynediol has a pH in the range of about 6.0 to about 11.

0.

8. The method of claim 1, wherein the solution comprising 1,4-butynediol has a pH of about 9.0 to about 10.

0.

9. The process of claim 1, wherein the process produces butanol as a byproduct in an amount in the range of less than about 3.0 wt. %, based on the total weight of the butanol and the 1,4-butanediol.

10. A catalyst for preparing 1,4-butanediol, the catalyst comprising: A skeleton metal catalyst, wherein the skeleton metal catalyst is composed of a first element, a second element and a promoter; wherein the promoter is cerium, the first element is Ni and the second element is aluminum; and wherein aluminum is present in an amount from greater than about 40 wt % to about 60 wt % of the catalyst.

11. The catalyst of claim 10, wherein cerium is present in an amount ranging from about 1 wt% to about 5.0 wt% of the catalyst.

12. The catalyst of claim 10, wherein cerium is present in an amount ranging from about 1.5 wt% to about 3.0 wt% of the catalyst.

13. A method for preparing a catalyst, the method comprising: Melting and mixing cerium oxide, Ni and aluminum to form an alloy, Wherein the aluminum is present in an amount ranging from greater than about 40 wt % to about 60 wt % based on the total weight of the cerium oxide, Ni and aluminum.

14. The method of claim 13, wherein Ni is present in an amount ranging from about 40 wt% to about 60 wt% based on the total weight of the cerium oxide, Ni, and aluminum.

15. The method of claim 13, wherein cerium oxide is present in an amount ranging from about 1 wt% to about 5 wt% based on the total weight of the cerium oxide, Ni, and aluminum.

16. The method of claim 13, wherein during said melting and mixing, cerium oxide is converted to cerium in said alloy.

17. The method according to claim 13, further comprising: The alloy is contacted with an alkaline aqueous solution to produce the catalyst.

18. The method of claim 13, wherein the catalyst is a skeletal metal catalyst.

19. A catalyst produced by the method according to claim 13.

Images