CATALYST, METHOD FOR PREPARATION THEREOF, AND SELECTIVE HYDROGENATION PROCESS - Patent application

Abstract

The present invention relates to a process for making 1,4-butanediol. The process can include reacting a solution containing 1,4-butynediol with hydrogen in the presence of an effective amount of a catalyst. The catalyst can include copper.

Description

[Technical field]

[0001] The present invention relates to a catalyst, more particularly to a catalyst for preparing 1,4 butanediol, a method for its preparation, a selective hydrogenation process using the catalyst, and an alloy precursor for preparing the catalyst. [Background technology]

[0002] Skeletal metal nickel catalysts in particulate fixed-bed form are commonly used industrially to make butanediol (BDO), a component in making polyesters from the unsaturated compound 1,4 butynediol (BYD). One form of skeletal metal nickel catalyst is made by the Raney process, which starts with an alloy containing at least two metals, such as nickel and aluminum. Optionally, other metals or compounds are added in smaller amounts as promoters to increase the activity, selectivity, or durability of the catalyst.

[0003] US Patent No. 6,262,317 discloses a process for preparing 1,4-butanediol by continuous catalytic hydrogenation of 1,4-butynediol. The process comprises 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 of the elements. The catalyst preferably further comprises at least one element selected from elements of main groups II, III, IV, and VI, elements of transition groups II, III, IV, and V of the periodic table of the elements, and a lanthanide as a promoter to increase activity. The promoter content of the catalyst is generally up to 5% by weight. The catalyst may be a precipitated, supported, or skeletal catalyst.

[0004] China Patent No. 201210212109.2 discloses a method for preparing and activating a framework metal nickel-aluminum-X catalyst for the hydrogenation preparation of 1,4-butanediol from 1,4-butynediol, where X represents Mg, B, Sr, Cr, S, Ti, La, Sn, W, Mo, or Fe.

[0005] US Patent Application No. 62 / 715,926 discloses a process for making 1,4-butanediol. The process involves reacting a solution containing 1,4-butynediol with hydrogen in the presence of a catalyst containing cerium as a promoter. The process can reduce significant formation of butanol by-product.

[0006] The catalyst typically has a predictable limited life. The process produces n-butanol, acetals (e.g., 2-(4-hydroxybutoxy)tetrahydrofuran), and other by-products at a gradually increasing rate until a maximum specification limit is reached, which defines the end of the useful life of the catalyst in the bed. Acidic Al species present in skeletal metal catalysts, such as hydrous alumina residues from the leaching process, are considered one major cause in producing by-products including butanol and acetals. Skeletal metal catalysts generally may contain small amounts of added elements as promoters, whose functions include improving the activity, selectivity, and stability of the catalyst in the chemical environment of a given hydrogenation process. Some promoters for skeletal metals, such as traditional Mo, Cr, or Fe, may actually increase the formation of butanol by-products 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 combinations still cannot adequately suppress the formation of butanol and acetals. Butanediol is a major component in making polyesters. Because there are impurity limitations on butanediol for downstream uses, reducing the contaminants in butanediol during the process for making it can, for example, significantly reduce the costs associated with later separating the impurities from the butanediol (e.g., distillation). Summary of the Invention

[0007] The present invention provides a process for making 1,4-butanediol from 1,4-butynediol solution in the presence of a catalyst comprising copper. The process significantly and unexpectedly reduces the amount of the main by-product acetal (2-(4-hydroxybut)tetrahydrofuran), in addition to maintaining desirable low levels of another major by-product, n-butanol, in the final 1,4-butanediol product.

[0008] Thus, one example of the present invention is a process for making 1,4-butanediol. The process can include reacting a solution containing 1,4-butynediol with hydrogen in the presence of a catalyst that includes copper as a promoter.

[0009] Another example of the present invention is an alloy precursor for a catalyst for making 1,4-butanediol. The alloy precursor can include a first metal, a second metal, and copper in the range of about 1% to about 10% by weight of the alloy precursor.

[0010] Another example of the present invention is a catalyst for making 1,4-butanediol. The catalyst can be a skeletal metal catalyst that includes copper as a promoter.

[0011] Another example of the present invention is a process for preparing a catalyst. The process may include melting and mixing copper, a first element, and a second element to form an alloy precursor, followed by activation using an alkaline solution to form a catalyst. The first element may be Ni and the second element may be aluminum. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described with reference to the embodiments of the present invention, in order to provide those skilled in the art with a better understanding of the technical solutions of the present disclosure.

[0013] A number modified by "about" herein means that the number may vary by 10%. A numerical range modified by "about" herein means that the upper and lower limits of the numerical range may vary by 10%. Butanol, n-butanol, and 1-butanol are all synonymous and interchangeable for our purposes.

[0014] An example of the present invention is a process for making 1,4-butanediol. The process may include reacting a solution containing 1,4-butynediol with hydrogen in the presence of an effective amount of a catalyst containing copper as a promoter. An "effective amount of catalyst" herein refers to a process that achieves at least about 95%, preferably at least about 99%, overall conversion of the starting butynediol with good selectivity to 1,4-butanediol. The promoter is a minor component in the catalyst compared to other major components such as nickel and aluminum to enhance the activity, selectivity, or durability of the catalyst.

[0015] The solution containing 1,4-butynediol may be technical grade 1,4-butynediol, which is in the form of an aqueous solution and may further contain components from the butynediol synthesis, such as bismuth, aluminum, or silicon compounds, as insoluble or dissolved components. The main solvent for the solution containing 1,4-butynediol is usually water. The solution containing 1,4-butynediol may also contain other solvents, such as methanol, ethanol, propanol, butanol, or recycled 1,4-butanediol products. The solution containing recycled 1,4-butanediol products may contain a lower 1,4-butynediol content than one containing only water as solvent. The 1,4-butynediol content in the solution is generally 5-90% by weight of the solution, preferably 10-80% by weight, particularly preferably 10-50% by weight. In one embodiment, the solution containing 1,4-butynediol is 100% pure butynediol.

[0016] The solution containing 1,4-butynediol may have a pH ranging from about 4.0 to about 11.0, preferably from about 7.5 to about 10.0. The solution pH may be inherent to the process conditions such as butynediol quality, temperature, pressure, etc., or may be optionally achieved by adjustment with a small amount of dilute base such as NaOH solution.

[0017] The hydrogen required for the reaction is preferably used in pure form. However, it may also contain further components such as methane and carbon monoxide. The hydrogen pressure applied to the fixed bed reactor for this process may range from about 15 to about 30 MPa. The inlet temperature of the fixed bed reactor may range from about 80°C to about 120°C. The flow rate of the feed solution, in combination with an effective amount of catalyst, is selected by the skilled artisan to allow a selected conversion rate, thereby achieving the desired overall conversion level of butynediol, i.e., reaction with hydrogen to form the product. The selected conversion rate of butynediol then depends on whether the process stream is partially recycled to the reactor inlet. In the case of a non-recycled process stream, the selected conversion rate results in a high overall conversion rate, for example, greater than 98% by weight of 1,4 butynediol in a "single pass". Similarly high levels of overall conversion may also be achieved at variable rates using a partially recycled process stream, for example, where 10-20% of the process stream at the reactor outlet is taken as the final product and the other 80-90% is returned to the inlet.

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

[0019] The catalyst may further comprise at least a first element selected from the group consisting of Ni, Co, Fe, and mixtures thereof. In one embodiment, the first element is Ni. The catalyst may further comprise at least a second element selected from the group consisting of aluminum, molybdenum, chromium, iron, 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 cobalt, skeletal metal nickel / molybdenum, skeletal metal nickel / chromium, skeletal metal nickel / chromium / iron or rhenium sponge.

[0021] Copper may be present in the catalyst in an amount ranging from about 1.0% to about 20.0% by weight of the catalyst, preferably from about 1.0% to about 12.0% by weight, and more preferably from about 2.0% to about 8.0% by weight.

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

[0023] When a fixed bed reactor is used in the process of the present invention, the space velocity of the solution and gas flowing through the fixed bed of catalyst is not limited.Those skilled in the art can adjust the space velocity of the solution and gas to obtain an optimal yield of 1,4-butanediol with a small amount of products such as butanol and acetal.

[0024] The catalyst according to the invention may contain only one type of catalyst or a mixture of several types of catalyst. The mixture of several types of catalyst may be present as a pseudo-homogeneous mixture or as a structured bed, where each individual reaction zone is composed of a pseudo-homogeneous catalyst bed. It is also possible to combine the processes, for example to use one catalyst type at the start of the reaction and a mixture further downstream.

[0025] The process may produce in the range of less than about 1.0 wt. % of acetal as a by-product, based on the total weight of the acetal, butanol, and 1,4-butanediol when the solution containing 1,4-butynediol has a pH of 7.5 or greater, preferably less than about 0.5 wt. %, and more preferably less than about 0.25 wt. %.

[0026] In one embodiment of the process for making 1,4-butanediol, the catalyst is a framework element catalyst. The catalyst comprises at least a first element selected from the group consisting of Ni, Co, Fe, and mixtures thereof, at least a second element selected from the group consisting of aluminum, molybdenum, chromium, iron, tin, zirconium, zinc, titanium, vanadium, and mixtures thereof, and copper as a promoter. The copper is present in an amount ranging from about 1.0% to about 12.0% by weight of the catalyst. The solution containing 1,4-butynediol has a pH of about 4.0 to about 11.0. The process produces acetal as a by-product in the range of less than about 1.0% by weight, preferably less than about 0.5% by weight, and more preferably less than about 0.25% by weight, based on the total weight of acetal, butanol, and 1,4-butanediol when the solution containing 1,4-butynediol has a pH of 7.5 or greater.

[0027] Another example of the present invention is an alloy precursor for a catalyst for making 1,4-butanediol. The alloy precursor can include a first metal, a second metal, and copper in the range of about 1.0% to about 10.0% by weight, preferably about 2.0% to 7.0% by weight of the alloy precursor.

[0028] In one embodiment, copper ranges from about 2.0% to about 5.0% by weight of the alloy precursor.

[0029] In one embodiment, the first metal is Ni in the range of about 30% to about 60% by weight of the alloy precursor and the second metal is Al in the range of about 40% to about 65% by weight of the alloy precursor. In another embodiment, the first metal is Ni in the range of about 40% to about 49% by weight of the alloy precursor and the second metal is Al in the range of about 50% to about 60% by weight of the alloy precursor.

[0030] Another example of the present invention is a catalyst for making 1,4-butanediol. The catalyst can include a skeletal metal catalyst including copper as a promoter. The copper can be present in the catalyst in an amount ranging from about 1.0% to about 10.0% by weight of the catalyst, preferably from about 2.0% to about 8.0% by weight. In one embodiment including about 1.0% to about 10.0% by weight of copper, the first element of the skeletal metal is nickel and the second element of the skeletal metal is aluminum.

[0031] Another example of the present invention is a process for preparing a catalyst. The process can include melting and mixing copper, a first element, and a second element to form an alloy precursor.

[0032] The first element may be selected from the group consisting of Ni, Co, Fe, and mixtures thereof. The second element may be selected from the group consisting of aluminum, molybdenum, chromium, iron, tin, zirconium, zinc, titanium, vanadium, and mixtures thereof. In one embodiment, the first element is Ni and the second element is aluminum. Ni may be present in an amount ranging from about 30% to about 60% by weight, preferably about 40% to about 49% by weight, based on the total weight of the alloy precursor. Aluminum may be present in an amount ranging from about 40% to about 65% by weight, preferably about 50% to 60% by weight, based on the total weight of the alloy precursor. Copper may be present in an amount ranging from about 1.0% to about 10.0% by weight, preferably about 2.0% to about 6.0% by weight, based on the total weight of the alloy precursor.

[0033] In one embodiment, the process of preparing the catalyst further comprises activating the alloy precursor by contacting the alloy precursor with an alkaline solution. The alkaline solution can be an aqueous solution of sodium hydroxide or potassium hydroxide having a concentration ranging from 1% to 25% by weight. In one embodiment, the alkaline solution is continuously pumped through the alloy precursor bed to activate the alloy precursor. In another embodiment, the alloy precursor particles are added in batches to the alkaline solution to activate the alloy precursor. In one embodiment, the catalyst is a skeletal metal catalyst.

[0034] In one embodiment, the process of preparing the catalyst includes melting and mixing copper, a first element, and a second element to form an alloy precursor, and contacting the alloy precursor with an alkaline aqueous solution to produce the catalyst. The first element is selected from the group consisting of Ni, Co, Fe, and mixtures thereof, and the second element is selected from the group consisting of aluminum, molybdenum, chromium, iron, tin, zirconium, zinc, titanium, vanadium, and mixtures thereof. The copper is present in an amount ranging from about 1.0 wt.% to about 10.0 wt.% based on the total weight of the catalyst. In one embodiment comprising about 1.0 wt.% to about 12.0 wt.% copper, the first element of the skeletal metal is nickel and the second element of the skeletal metal is aluminum.

[0035] Another example of the present invention is a catalyst produced by the process for preparing a catalyst according to one embodiment of the present invention.

[0036] The description of various embodiments of the present invention is presented for illustrative purposes and is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms used in this specification are selected to enable those skilled in the art to understand the principles of the embodiments, practical applications or technical improvements of the technology found in the market, or the embodiments disclosed herein.

[0037] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to the following examples. EXAMPLES

[0038] Example 1 Catalyst preparation An alloy precursor containing 58 wt% Al, 2.5 wt% Cu, and 39.5 wt% Ni was formed by melting and mixing the three components, which were then crushed and sieved into alloy precursor particles having diameters ranging from 8 to 12 mesh size or from about 2 mm to about 3 mm.

[0039] A 390 g portion of the alloy precursor particles was placed in a beaker to form a "bed". This bed of alloy precursor particles was converted to a portion of catalyst by contacting it with a "leachate", which involves pumping five portions of aqueous NaOH solution continuously at a constant rate through the alloy precursor bed. Each portion of the aqueous NaOH solution was 18 liters, and the strength of the five portions was increased during the process by 1%, then 2%, 3%, 4% to a final 5%, respectively. Each portion of the aqueous NaOH solution was delivered through the alloy precursor bed for 40 minutes while a submerged cooling coil (with internal water flow) was used to control the temperature of the process to a target of 38°C.

[0040] The catalyst was then washed with 2 liters of 0.25% NaOH solution for 10 minutes, then with water at 45° C. until the effluent wash water reached a pH of 9.

[0041] This portion of catalyst had the following assay (wt%) by ICP analysis: 54.6Ni, 41.7Al, 3.5Cu, 0.2Fe.

[0042] Catalyst Testing The prepared catalyst was kept water-wet when loaded into a vertical column reactor with bed dimensions of about 0.5 inch inner diameter and about 6 inch height, in a catalyst bed with a volume of 18 mL.

[0043] A reactant feed solution was prepared by dissolving 40% 1,4 butanediol (representing the recycled "BDO" product) in water along with 10 wt. % 2-butyne-1,4 diol. The overall organic compound content was nominally 50% and water was 50%. The pH of this freshly made mixture varied from about 4 to about 5.5. As an additional variable for subsequent catalyst testing, an additional portion of the reactant feed solution was prepared by adding a small amount of 15% NaOH solution and then adjusted to a pH in the range of about 7.0 to about 8.5.

[0044] For catalytic testing, the reaction conditions used were an inlet temperature of 100°C, peak temperature: 150°C (outlet temperature), hydrogen pressure = approximately 2500 psig (16-17 MPa), and a controllable liquid feed flow rate. 0.25 mL / min is the default liquid flow rate, with a range of 0.10-2.5 being feasible. Once the flow rate is varied, it is then maintained at a constant level for several days to achieve a steady level of product. A cocurrent upflow of H2 gas (300 mL / min) and liquid is maintained throughout the testing process.

[0045] Product assays, stated as weight percent organic products, were determined by GC analysis using a Restek Stabilwax 30 x 0.32 x 0.5 column, 90% ethanol solvent, diglyme as an internal standard, and a flame ionization detector. Yields reported for each condition in Tables 1 and 2 are averages from samples taken after each 8 hour continuous run.

[0046] The primary by-product of interest, n-butanol ("n-butanol, BuOH"), ranges from 0.23 to 0.35% across various pH conditions. When a higher pH of the feed solution is used, the butanol yield is lower. The second by-product, 2-(4-hydroxybutoxy)tetrahydrofuran, a cyclized acetal formed by reaction of the product with the feed molecule and dehydration, is listed as "acetal" in Tables 1 and 2. As shown in Table 1, the acetal varies from 0.17 to 0.38% at different pHs.

[0047] The pH of the reactant feed solutions used, the time spent at pH conditions, and a summary of the two main by-products are listed in Table 1.

[0048] Example 2 Catalyst preparation A similar method to that of Example 1 was used, except that the alloy had a composition of 58 wt% Al, 3.8 wt% Cu, and 38.2 wt% Ni. The resulting catalyst composition was 42.6% Al, 52.3% Ni, 5.0% Cu, 0.2% Fe.

[0049] Catalyst Testing Tests are conducted similar to those in Example 1 to show the Ce-Ni improvement and Cu content variation compared to Example 1.

[0050] Comparative example (Ce-Ni) Catalyst preparation The alloy precursor used had the following composition: 61.5% Al, 34.9% Ni, 2.1% Ce. The activation and washing procedures were similar to those in Example 1, except that the concentrations of the NaOH solutions were 0.9, 1.75, 2.6, 3.5, and 4.35%, respectively. The resulting catalyst composition was 51.5% Al, 45.2% Ni, 3.3% Ce.

[0051] Catalyst Testing The test conditions and methods were as described in Example 1. The test results are shown in Table 2. As summarized in Table 2, the butanol by-products ranged from 0.21 to 0.55%, and the acetals ranged from 0.40 to 0.65.

[0052] As shown in Tables 1 and 2 using the catalyst according to one embodiment of the present invention, the use of copper instead of cerium as a promoter shows a significant improvement in lowering the amount of acetal by-products while maintaining similar or slightly lower levels of butanol by-products. These by-products have maximum allowable values ​​in full-scale industrial applications. Therefore, these reductions in acetal by-products are very significant in industrial applications, thereby extending the life of fixed-bed catalyst systems, often by months, leading to lower operating costs for users. There are also other advantages, such as lower cost and simpler use with Cu metal compared to CeO2.

[0053] [Table 1]

[0054] [Table 2]

[0055] The principles and embodiments of the present disclosure are described herein. The description of the embodiments of the present disclosure is only used to help understand the method of the present disclosure and its core idea. Meanwhile, for those skilled in the art, the present disclosure, regarding the scope of the present disclosure, the technical scheme is not limited to a specific combination of technical features, and should cover other technical schemes formed by combining the technical features or the equivalent features of the technical features without departing from the concept of the present invention. For example, the technical scheme can be obtained by replacing the features described above with similar features (but not limited to) as disclosed in the present disclosure. The present invention includes the following aspects. [1] 1. A process for making 1,4-butanediol, comprising: reacting a solution containing 1,4-butynediol with hydrogen in the presence of an effective amount of a catalyst; The process wherein the catalyst comprises copper. [2] 2. The process of claim 1, wherein the catalyst is in the form of a fixed bed, a suspension, or a combination thereof. [3] 3. The process of claim 2, wherein the catalyst is in the form of a fixed bed and has a particle size in the range of about 1 mm to about 8 mm. [4] 3. The process of claim 2, wherein the catalyst, in the form of the suspension, has a median particle size in the range of about 10 to about 100 μm. [5] 2. The process of claim 1, wherein the catalyst further comprises at least a first metal selected from the group consisting of Ni, Co, Fe, and mixtures thereof. [6] 6. The process of claim 5, wherein the first metal is Ni. [7] 6. The process of claim 5, wherein the catalyst further comprises at least a second metal selected from the group consisting of aluminum, molybdenum, chromium, iron, tin, zirconium, zinc, titanium, vanadium, and mixtures thereof. [8] 8. The process of claim 7, wherein the second metal is aluminum. [9] 2. The process of claim 1, wherein the catalyst is a skeletal metal catalyst.

[10] 2. The process of claim 1, wherein copper is present in an amount ranging from about 1.0% to about 12.0% by weight of the catalyst.

[11] 2. The process of claim 1, wherein copper is present in an amount ranging from about 2.0% to about 8.0% by weight of the catalyst.

[12] 2. The process according to claim 1, wherein the solution containing 1,4-butynediol has a pH in the range of about 4.0 to about 11.0.

[13] 2. The process of claim 1, wherein the solution containing 1,4-butynediol has a pH of about 7.5 to 10.

[14] 2. The process of claim 1, wherein the process produces the acetal as a by-product in the range of less than about 0.5 weight percent based on the total weight of butanol, acetal, and the 1,4-butanediol when the solution containing 1,4-butynediol has a pH of 7.5 or greater.

[15] 2. The process of claim 1, wherein the process produces the acetal as a by-product in the range of less than 0.25 wt. % based on the total weight of butanol, acetal, and the 1,4-butanediol when the solution containing 1,4-butynediol has a pH of 7.5 or greater.

[16] 1. An alloy precursor for a catalyst for making 1,4-butanediol, comprising: a first metal, a second metal, and copper in the range of about 1.0% to about 10.0% by weight of the alloy precursor.

[17] 17. The alloy precursor according to item 16, wherein copper is in the range of about 2.0% to about 5.0% by weight of said alloy precursor.

[18] 17. The alloy precursor according to claim 16, wherein the first metal is Ni in the range of about 30% to about 60% by weight of the alloy precursor, and the second metal is Al in the range of about 40% to about 65% by weight of the alloy precursor.

[19] 17. The alloy precursor according to claim 16, wherein the first metal is Ni in the range of about 40% to about 49% by weight of the alloy precursor, and the second metal is Al in the range of about 50% to about 60% by weight of the alloy precursor.

[20] 19. A catalyst prepared from an alloy precursor according to claim 18, wherein the catalyst is a skeletal metal catalyst containing copper as a promoter.

[21] 21. The catalyst of claim 20, wherein copper is present in an amount ranging from about 1.0% to about 12.0% by weight of the catalyst.

[22] 22. The catalyst of claim 21, wherein copper is present in an amount ranging from about 2.0% to about 8.0% by weight of the catalyst.

[23] A process for preparing a catalyst, the process comprising: melting and mixing copper, a first metal, and a second metal to form an alloy precursor; wherein the first metal is selected from the group consisting of Ni, Co, Fe, and mixtures thereof, and the second metal is selected from the group consisting of aluminum, molybdenum, chromium, iron, tin, zirconium, zinc, titanium, vanadium, and mixtures thereof.

[24] 24. The process of claim 23, wherein the first metal is Ni and the second metal is Aluminum.

[25] 25. The process of claim 24, wherein Ni is present in an amount ranging from about 40% to about 49% by weight of the alloy precursor, Aluminum is present in an amount ranging from about 50% to about 60% by weight of the alloy precursor, and Copper is present in an amount ranging from about 1.0% to about 10.0% by weight of the alloy precursor.

[26] contacting the alloy precursor with an aqueous alkaline solution to produce the catalyst; 26. The process of claim 25, wherein the catalyst comprises copper in an amount ranging from about 1.0% to 12.0% by weight of the catalyst.

[27] 26. The process of claim 25, wherein the catalyst is a skeletal metal catalyst.

Claims

1. 1. A process for making 1,4-butanediol, comprising: reacting a solution containing 1,4-butynediol with hydrogen in the presence of an effective amount of a catalyst; The process wherein the catalyst comprises copper and the solution comprising the 1,4-butynediol has a pH of from 7.5 to 10.

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

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

4. 3. The process of claim 2, wherein the catalyst, in the form of the suspension, has a median particle size in the range of 10 to 100 μm.

5. 10. The process of claim 1, wherein the catalyst further comprises at least a first metal selected from the group consisting of Ni, Co, Fe, and mixtures thereof.

6. The process of claim 5 wherein the first metal is Ni.

7. 6. The process of claim 5, wherein the catalyst further comprises at least a second metal selected from the group consisting of aluminum, molybdenum, chromium, iron, tin, zirconium, zinc, titanium, vanadium, and mixtures thereof.

8. The process of claim 7 wherein the second metal is aluminum.

9. The process of claim 1 , wherein the catalyst is a skeletal metal catalyst.

10. 2. The process of claim 1, wherein copper is present in an amount ranging from 1.0% to 12.0% by weight of the catalyst.

11. 2. The process of claim 1, wherein copper is present in an amount ranging from 2.0% to 8.0% by weight of the catalyst.

12. 2. The process of claim 1, wherein the process produces the acetal as a by-product in the range of less than 0.5 weight percent, based on the total weight of butanol, acetal, and the 1,4-butanediol.

13. 2. The process of claim 1, wherein the process produces the acetal as a by-product in the range of less than 0.25 wt.%, based on the total weight of butanol, acetal, and the 1,4-butanediol.

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