Preparation method and application of alkali metal or rhenium modified aluminum oxide catalyst

Abstract

Provided herein are alkali metal or rhenium modified alumina catalysts, methods for their preparation, and methods for their use in double bond isomerization of aliphatic light internal olefins to aliphatic alpha-olefins and in reverse isomerization reactions.

Description

Technical Field

[0001] The present disclosure relates to alkali metal or rhenium modified alumina catalysts, methods of their preparation and their use in isomerization reactions. Background Art

[0002] The comonomer for producing linear low-density polyethylene and polybutene is 1-butene. And in the presence or absence of 2-butene, 1-butene is converted to produce propylene or linear olefins via metathesis based on product requirements. Currently, 1-butene is produced in petrochemical plants by separating the C4 fraction from naphtha cracking. When these processes are completed, a C4 raffinate-III containing a large amount of 2-butene remains. Therefore, it is necessary to convert 2-butene into 1-butene with higher added value through reverse / positional isomerization. There are other possibilities for producing isobutylene through skeletal isomerization, producing octene and decene through oligomerization, and producing other light hydrocarbons through cracking over the catalyst. More importantly, the catalysts used still suffer from low selectivity and rapid deactivation for 1-butene. There is commercial comonomer production through the following: isomerization of 2-butene from raffinate-III to produce 1-butene, and then metathesis in the presence of a magnesium oxide catalyst to produce 1-hexene. However, this catalyst deactivates rapidly and is very sensitive to moisture. Summary of the Invention

[0003] Applicants have identified the need to develop highly selective and stable catalysts for the isomerization of aliphatic light internal olefins to aliphatic alpha-olefins. Compositions and methods are provided herein to address these shortcomings of the prior art and provide other additional or alternative advantages. The present disclosure provides several embodiments of methods for preparing potassium- or rhenium-modified alumina catalysts and methods for using these resulting compositions in isomerization reactions.

[0004] Embodiments include methods for isomerizing olefin bonds in the presence of a gamma-alumina-based catalyst. One such method includes the steps of heating the gamma-alumina-based catalyst to a temperature in the range of about 450° C. to about 550° C. in an isomerization reactor to produce an activated gamma-alumina-based catalyst, cooling the activated gamma-alumina-based catalyst to a temperature below 450° C., and supplying a stream rich in aliphatic light internal olefins to the isomerization reactor to convert a portion of the stream rich in aliphatic light internal olefins to a stream rich in aliphatic alpha-olefins. The activated gamma-alumina-based catalyst is cooled in the presence of nitrogen. The stream rich in aliphatic light internal olefins may contain greater than 30% by weight of 2-butene. In some embodiments, the activated gamma-alumina-based catalyst contains an alkali metal hydroxide in the range of 5% by weight (wt%) to 10% by weight or rhenium oxide in the range of 3% by weight to 8% by weight. Surprisingly, it has been discovered that activated gamma-alumina-based catalysts containing an alkali metal hydroxide in the range of 5 weight percent (wt%) to 10 weight percent or rhenium oxide in the range of 3 weight percent to 8 weight percent exhibit improved stability and a longer duration of activity before the catalyst becomes deactivated. In some embodiments, the activated gamma-alumina-based catalyst has a surface area in the range of about 175 to 250 square meters per gram. In some embodiments, the alkali metal hydroxide is potassium hydroxide. In some embodiments, the isomerization reactor is a tubular fixed bed reactor. In some embodiments, the process may be a process for the isomerization of 2-butene to 1-butene.

[0005] Embodiments include methods for preparing a gamma-alumina-based catalyst. One such method includes the steps of calcining a gamma-alumina-based support at a temperature in the range of about 450°C to about 550°C to produce a calcined gamma-alumina-based support, treating the calcined gamma-alumina-based support with an aqueous alkali metal hydroxide solution to form an impregnated gamma-alumina-based support, drying the impregnated gamma-alumina-based support at a temperature in the range of about 80°C to about 120°C, and calcining the impregnated alumina support at a temperature in the range of about 450°C to about 550°C to produce a gamma-alumina-based catalyst. The aqueous alkali metal hydroxide solution may be sprayed onto the gamma-alumina-based support in a rotary impregnator unit. The aqueous alkali metal hydroxide solution may be sprayed onto the gamma-alumina-based support in a rotary impregnator unit at a gauge pressure of about 1.5 barg to about 4 barg. The amount of alkali metal hydroxide in the gamma-alumina-based catalyst ranges from 5% to 10% by weight. In some embodiments, the aqueous alkali metal hydroxide solution contains potassium hydroxide. The aqueous alkali metal hydroxide solution may contain potassium hydroxide at a molar concentration ranging from about 4 M to about 8 M. In some embodiments, the gamma-alumina based support contains a surface area ranging from about 175 m 2 / g-about 250m 2 In some embodiments, the gamma-alumina-based support contains gamma-alumina-based spheres having a pore volume ranging from about 0.5 milliliters per gram (mL / g) to about 0.75 mL / g.

[0006] Another method for preparing a gamma-alumina-based catalyst includes the steps of calcining a gamma-alumina-based support at a temperature in the range of about 450° C. to about 550° C. to produce a calcined gamma-alumina-based support, treating the calcined gamma-alumina-based support with an aqueous perrhenic acid solution to form an impregnated gamma-alumina-based support, drying the impregnated gamma-alumina-based support at a temperature in the range of about 80° C. to about 120° C., and calcining the impregnated alumina support at a temperature in the range of about 450° C. to about 550° C. to produce a gamma-alumina-based catalyst. The aqueous perrhenic acid solution may be sprayed onto the gamma-alumina-based support in a rotary impregnator unit. The aqueous perrhenic acid solution may be sprayed onto the gamma-alumina-based support in a rotary impregnator unit at a gauge pressure of about 2 barg. The gamma-alumina-based catalyst may contain rhenium oxide in a range of 3% to 8% by weight. In some embodiments, the gamma-alumina based support has a surface area in the range of about 175 m 2 / g-about 250m 2 In some embodiments, the gamma-alumina-based support contains gamma-alumina-based spheres having a pore volume ranging from about 0.5 mL / g to about 0.75 mL / g. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The embodiments will be readily understood by the following detailed description taken in conjunction with the accompanying drawings. For ease of description, identical reference numerals denote identical structural elements or procedures in the method. The embodiments are described by way of example, but not by way of limitation, in the accompanying drawings. The present disclosure may be better understood by reference to the following drawings. These drawings illustrate the principles of the disclosure and are not intended to limit the scope of the disclosure.

[0008] Figure 1 is a diagrammatic representation of a process for isomerizing olefinic bonds in the presence of a gamma-alumina based catalyst, according to an embodiment.

[0009] Figure 2 is a diagrammatic representation of a method for preparing a K / γ-Al2O3 catalyst according to an embodiment.

[0010] Figure 3 is a diagrammatic representation of a method for preparing a Re2O7 / γ-Al2O3 catalyst according to an embodiment.

[0011] Figure 4is a graphical representation of catalyst rigor and reproducibility over run time for butene isomerization reactions according to an embodiment.

[0012] Figure 5 is a diagram illustrating the production of 1-butene using a K / γ-Al2O3 catalyst under different reaction conditions according to an embodiment.

[0013] Figure 6 is a diagram illustrating the production of 1-butene using 5 wt % Re2O7 / γ-Al2O3 under reaction conditions according to an embodiment. DETAILED DESCRIPTION

[0014]

[0014] This disclosure describes various embodiments related to alkali metal alumina catalyst compositions and methods used in isomerization reactions. Some embodiments include the isomerization reaction of aliphatic light internal olefins to aliphatic alpha-olefins.

[0015] Embodiments of alkali metal modified alumina catalysts or rhenium modified alumina catalysts. Methods of preparing these catalysts include the steps of calcining a gamma-alumina support, treating the gamma-alumina support with a solution of an alkali metal hydroxide (e.g., KOH) or a solution of perrhenic acid (HReO4) to form an impregnated alumina support containing K / γ-Al2O3 or Re2O7 / Al2O3, and drying and calcining the impregnated alumina support to form an inverse catalyst. In some embodiments, the impregnated alumina support contains from about 5 weight percent (wt%) to about 10 wt% potassium hydroxide impregnated on the gamma-Al2O3 support. In some embodiments, the impregnated alumina support contains about 8 wt% potassium hydroxide impregnated on the gamma-Al2O3 support. In some embodiments, the impregnated alumina support contains about 9.5 wt% potassium hydroxide impregnated on the gamma-Al2O3 support. In some embodiments, the impregnated alumina support contains from about 3 wt% to about 8 wt% rhenium oxide impregnated on a γ-Al 2 O 3 support. In some embodiments, the impregnated alumina support contains about 5 wt% rhenium impregnated on a γ-Al 2 O 3 support.

[0016] Embodiments of the foregoing catalysts are used in the isomerization of aliphatic light internal olefins to aliphatic alpha-olefins. Methods for using these catalysts in the isomerization reaction include activating and cooling the catalyst before introducing the aliphatic light internal olefin at reaction temperature. Some embodiments include processing 2-butene to produce a 1-butene-rich stream by supplying 2-butene to a reverse isomerization reactor containing an alkali metal alumina catalyst. These catalysts exhibit high selectivity for the aforementioned 1-butene production.

[0017] In the following description, in order to provide a thorough understanding of each embodiment, reference is made to the accompanying drawings that form a part of the present disclosure and many details are set forth. In other cases, well-known processes, devices and systems are not described in particular detail to avoid unnecessarily obscuring the various embodiments. In addition, the description of each embodiment may omit some features or details so as not to obscure the various embodiments. The accompanying drawings may provide descriptions of some of the various embodiments that can be used to practice the subject matter of the present disclosure. Other embodiments may be used and logical changes may be made without departing from the scope of the present disclosure.

[0018] The description may use the phrases "in some embodiments," "in various embodiments," "in one embodiment," or "in multiple embodiments," each of which may refer to one or more of the same or different embodiments. The terms "comprising" (and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "includes" and "include"), or "containing" (and any form of containing, such as "contains" and "contain"), etc., are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0019] The term "about" refers to a range of values that include the stated value and that one of ordinary skill in the art would reasonably consider to be similar to the stated value. In embodiments, "about" refers to values within the standard deviation of measurements generally accepted in the art. In a non-limiting embodiment, when the term "about" is used with a particular value, then "about" refers to a range extending to ±10%, alternatively ±5%, or alternatively ±1%, or alternatively ±0.5% of the stated value. In embodiments, "about" refers to the stated value.

[0020] Figure 1is a diagrammatic representation of a method 100 for isomerizing olefin bonds in the presence of a gamma-alumina-based catalyst, according to an embodiment. Method 100 includes step 102 of heating the gamma-alumina-based catalyst in an isomerization reactor to a temperature in the range of about 450° C. to about 550° C. The method includes step 104 of producing and extracting an activated gamma-alumina-based catalyst. In some embodiments, the activated gamma-alumina-based catalyst contains an alkali metal hydroxide in the range of 5% to 10% by weight or rhenium oxide in the range of 3% to 8% by weight. Step 106 of the method includes cooling the activated gamma-alumina-based catalyst to a temperature below 450° C. The activated gamma-alumina-based catalyst is cooled in the presence of nitrogen. In step 108, a stream rich in aliphatic light internal olefins is supplied to the isomerization reactor, and in step 110, a portion of the stream rich in aliphatic light internal olefins is converted to a stream rich in aliphatic alpha-olefins. In some embodiments, the aliphatic alpha-olefin-rich stream is supplied to a separation unit to purify the aliphatic alpha-olefin.

[0021] Figure 2 is a diagrammatic representation of a method 200 for preparing a K / γ-Al2O3 catalyst according to an embodiment. Method 200 includes step 202 of calcining a γ-alumina-based support at a temperature in the range of about 450°C to about 550°C to produce a calcined γ-alumina-based support. Step 204 involves treating the calcined γ-alumina-based support with an aqueous solution of an alkali metal hydroxide to form an impregnated γ-alumina-based support. Step 206 involves drying the impregnated γ-alumina-based support at a temperature in the range of about 80°C to about 120°C. Step 208 involves calcining the impregnated alumina support at a temperature in the range of about 450°C to about 550°C to produce a γ-alumina-based catalyst.

[0022] Figure 3 is a diagrammatic representation of a method 300 for preparing a Re2O7 / γ-Al2O3 catalyst according to an embodiment. The method 300 includes a step 302 of calcining a γ-alumina-based support at a temperature in the range of about 450°C to about 550°C to produce a calcined γ-alumina-based support. Step 304 involves treating the calcined γ-alumina-based support with an aqueous perrhenic acid solution to form an impregnated γ-alumina-based support. Step 306 involves drying the impregnated γ-alumina-based support at a temperature in the range of about 80°C to about 120°C. The method 300 includes a step 308 of calcining the impregnated alumina support at a temperature in the range of about 450°C to about 550°C to produce a γ-alumina-based catalyst.

[0023] The method of preparing these catalysts includes the steps of calcining a gamma-alumina support, treating the gamma-alumina support with a solution of an alkali metal hydroxide (e.g., KOH) or a solution of perrhenic acid (HReO4) to form an impregnated alumina support containing K / γ-Al2O3 or Re2O7 / γ-Al2O3, and drying and calcining the impregnated alumina support to form the reverse catalyst. In some embodiments, the impregnated alumina support contains from about 5 weight percent (wt%) to about 10 wt% potassium hydroxide impregnated on the gamma-Al2O3 support. In some embodiments, the impregnated alumina support contains from about 3 wt% to about 8 wt% rhenium oxide impregnated on the gamma-Al2O3 support. In some embodiments, the gamma-alumina support is in the form of spheres. In some embodiments, the gamma-alumina support undergoes calcination at a temperature ranging from about 500°C to about 600°C. Calcination of the gamma-alumina support prior to the impregnation step facilitates water removal to ensure pore volume availability for the impregnation step with an alkali hydroxide (e.g., KOH) or perrhenic acid (HReO4) solution. Calcination of the impregnated alumina support results in water loss and the production of an oxide form of the alkali hydroxide (e.g., KOH) or perrhenic acid on the alumina (e.g., K / γ-Al2O3 or Re2O7 / γ-Al2O3) to establish the metal-support interaction.

[0024] Embodiments of the alumina support include crystalline phase aluminas such as γ-Al2O3 and θ-Al2O3. The surface area of the alumina support ranges from about 175 m2 / g (m 2 / g)-about 250m 2 / g. The pore volume of the alumina support ranges from about 0.5 milliliters per gram (mL / g) to about 0.75 mL / g. The pore diameter of the alumina support ranges from about -about The bulk density of the alumina support ranges from about 0.4 grams per milliliter (g / mL) to about 0.8 g / mL. The average diameter of the alumina support in the form of spherical pellets ranges from about 1.2 millimeters (mm) to about 3 mm. The average diameter of the alumina support in the form of extrudates / trilobes / quadrupoles ranges from about 1.6 mm to 2 mm. The crush strength of the alumina support in the form of spherical pellets ranges from about 4 decanewtons per millimeter (daN / mm) to about 15 daN / mm. The crush strength of the alumina support in the form of extrudates or trilobes ranges from about 2 daN / mm to about 4 daN / mm. In some embodiments, commercially available γ-Al2O3 spheres are obtained having the following properties: an average particle size of 1.2 mm to 2 mm, 200 m 2 / g to 225m 2The invention has a surface area of 1000 nm / m2 / g, a pore volume of 0.5 ml / g to 0.65 ml / g, a bulk density of 0.65 g / ml to 0.7 g / ml, a particle crush strength of 8 daN to 12 daN and a loss on ignition of less than 5 wt%.

[0025] Embodiments include the use of an alkali metal-modified alumina catalyst or a rhenium-modified alumina catalyst for double bond isomerization of aliphatic light internal olefins to aliphatic alpha-olefins (e.g., conversion of 2-butene to 1-butene) by reverse positional isomerization. One such method for olefin bond isomerization in the presence of a gamma-alumina-based catalyst includes the steps of heating the gamma-alumina-based catalyst to a temperature in the range of about 450° C. to about 550° C. in an isomerization reactor to produce an activated gamma-alumina-based catalyst, and cooling the activated gamma-alumina-based catalyst to a temperature below 450° C. and supplying a stream rich in aliphatic light internal olefins to the isomerization reactor to convert a portion of the stream rich in aliphatic light internal olefins to a stream rich in aliphatic alpha-olefins. The activated gamma-alumina-based catalyst contains an alkali metal hydroxide in the range of 5 weight percent (wt%) to 10 wt% or rhenium oxide in the range of 3 wt% to 8 wt%. In some embodiments, the conversion of the aliphatic light internal olefin-rich stream to the aliphatic alpha-olefin-rich stream is carried out at a temperature ranging from about 200°C to about 250°C and a pressure ranging from about 0 barg to about 30 barg.

[0026] Embodiments include the use of an alkali metal-modified alumina catalyst or a rhenium-modified alumina catalyst for the isomerization of aliphatic alpha-olefins to aliphatic light internal olefins (e.g., the conversion of 1-butene to 2-butene). One such method for isomerizing olefin bonds in the presence of a gamma-alumina-based catalyst includes the steps of heating the gamma-alumina-based catalyst to a temperature in the range of about 450° C. to about 550° C. in an isomerization reactor to produce an activated gamma-alumina-based catalyst, and cooling the activated gamma-alumina-based catalyst to a temperature below 450° C. and supplying an aliphatic alpha-olefin-rich stream to the isomerization reactor to convert a portion of the aliphatic alpha-olefin-rich stream to an aliphatic light internal olefin-rich stream. The activated gamma-alumina-based catalyst contains an alkali metal hydroxide in the range of 5 weight percent (wt%) to 10 wt% or rhenium oxide in the range of 3 wt% to 8 wt%. In some embodiments, the conversion of the aliphatic alpha-olefin rich stream to the aliphatic light internal olefin rich stream is carried out at a temperature ranging from about 25°C to about 100°C and a pressure ranging from about 0 barg to about 30 barg.

[0027] In some embodiments, the alkali metal modified alumina catalyst or the rhenium modified alumina catalyst is first activated at a temperature above the reaction temperature under nitrogen before the temperature is lowered to the reaction temperature. For example, the alkali metal modified alumina catalyst or the rhenium modified alumina catalyst undergoes an activation process under air at a temperature in the range of about 450°C to about 550°C to remove moisture from the catalyst for activation or regeneration of the catalyst. This step ensures that the active catalytic sites are exposed to reactant molecules for conversion. In addition, this step also increases the cycle time of the catalyst. After this catalyst activation or regeneration step, in some embodiments, the catalyst is purged with nitrogen to avoid contact between air and hydrocarbons during the reaction time.

[0028] Example

[0029] The various examples provided herein illustrate selected aspects of various embodiments of alkali metal-modified alumina catalysts or rhenium-modified alumina catalysts, methods of making these catalysts, and methods of using these catalysts in isomerization and reverse isomerization reactions.

[0030] Example 1

[0031] A potassium-modified alumina catalyst in the form of spherical pellets containing 8 wt% K / γ-Al2O3 was prepared. Commercially available γ-Al2O3 pellets were obtained with the following properties: average particle size of 1.2 mm to 2 mm, 200 m 2 / g to 225m 2The catalyst was prepared by incipient wetness impregnation of the support with an aqueous solution prepared by dissolving 2.7 grams of potassium hydroxide in 11 mL of DI water to make a clear solution. Impregnation was performed by contacting the impregnation solution prepared above with 18.4 grams of calcined alumina sphere support at room temperature. The calcined support was introduced into a rotatable impregnation drum, which rotated at 25 rpm and sprayed with the potassium-containing impregnation solution. The potassium hydroxide solution had a concentration of approximately 4.4 M. The amount of solution corresponded to the pore volume of the gamma-alumina support, which was measured by adding demineralized water dropwise to 10 g of the gamma-alumina support until the support was completely wetted. The measured amount of water (normalized to 1 gram of support) is 0.6 grams of water required to fully saturate 1 gram of alumina support. A 4.4M KOH solution is sprayed onto 800 grams of the final calcined catalyst using a pressure of 2 barg at a rate of 39 mL / min over a period of 12 minutes. The 4.4M KOH solution is allowed to act on the support for an additional 5 to 30 minutes to complete the impregnation step. The impregnated alumina support is then kept at room temperature for 2 hours and then dried at 120°C for 16 hours. The dried sample is then calcined in a downflow tubular reactor at 550°C with a heating rate of 5°C / min for 5 hours in the presence of air. After calcination, the catalyst is cooled in the presence of air and stored in a sealed container for isomerization of 2-butene to 1-butene. The final calculated composition of the catalyst is 8 wt% K / Al2O3. This method is robust and can be scaled up to prepare catalysts larger than laboratory scale quantities. The properties of the synthesized catalyst are provided in Table 1.

[0032] Table 1

[0033]

[0034] Example 2

[0035] About 7 grams of catalyst balls with an average diameter ranging from about 1.5 mm to about 2 mm, prepared as described in Example 1, were loaded into a tubular fixed bed reactor. The catalyst balls were accurately weighed and loaded into the reactor. Plug flow conditions were maintained. A thermocouple well was placed at the bottom of the catalyst bed. 13X molecular sieves were loaded above the catalyst bed to absorb moisture from the raw materials before contacting the catalyst bed. After loading, the catalyst was activated for the isomerization of 2-butene to 1-butene. The catalyst was activated at 550° C. under air for 6 hours, and then purged with air and nitrogen and cooled to 300° C. under nitrogen. Once the reaction temperature of 300° C. was reached, a feed containing 95% 2-butene and 5% isobutane was supplied to the reactor. Isobutane was used as an internal standard. The 2-butene feed was supplied to maintain a weight hourly space velocity (WHSV) of about 0.4 / hr to 0.5 / hr. The reactor outlet gas was analyzed by an on-line gas chromatograph (Agilent 6890) equipped with a flame ionization detector for hydrocarbon analysis and a thermal conductivity detector for ideal gas. The reactor and product molar flows were calculated using the internal standard isobutane based on its molar flow rate and the GC area. Figure 4 Figure 1 is a graphic representation of the stringency and reproducibility of the butene isomerization catalyst as a function of time on stream (TOS). No deactivation was observed for TOS tested for >100 hours at various temperatures.

[0036] Example 3

[0037] The 8 wt% K / Al2O3 catalyst was tested at a WHSV of 0.5 / hr by varying the reaction temperature at 300°C, 350°C, and 400°C and at atmospheric pressure. The activity results are shown in Figure 5 The formation of 1-butene increases with increasing reaction temperature.

[0038] Example 4

[0039] The catalyst method described in Example 1 was used to prepare K / Al2O3 catalyst in batches of 800 grams and in batches of approximately 10 kg. The catalyst was prepared in an impregnation drum. Calcined spherical alumina was introduced into a rotatable impregnation drum. The drum rotated at 25 rpm and sprayed with a ~4.4 M impregnation solution containing potassium. A KOH solution was sprayed over 12 minutes at a rate of 39 ml / min using a pressure of 2 barg for 800 g of the final calcined catalyst. After impregnation, the impregnation solution was allowed to act on the support for an additional 5 to 30 minutes. The impregnated support was dried at a temperature ranging from 80-120°C for 16-24 hours and then calcined at 550°C in air for 6 hours. The K / Al2O3 catalyst was tested in a pilot-scale fixed-bed reactor with an internal diameter of 150 mm and a length of 900 mm. The catalyst was tested for the isomerization of 1-butene to 2-butene under reaction conditions of 60°C, a WHSV of 1.5 / hr total feed, and a pressure of 6 barg. The commercial feed for the reaction was 0.1 mol% ethane, 3.5 mol% propane, 18.3 mol% isobutylene, 17.3 mol% n-butane, 60.3 mol% 1-butene, 0.1 mol% trans-2-butene, and 0.4 mol% cis-2-butene. Under these reaction conditions, the resulting stable product composition was 12.6 mol% 1-butene, 21.4 mol% trans-2-butene, 25.8 mol% cis-2-butene, and approximately 40.2 mol% inerts. At low reaction temperatures (e.g., 25°C-100°C), the K / Al2O3 catalyst is active for the isomerization of 1-butene to 2-butene and is stable for almost 1 month at a WHSV of 0.5 / hr relative to total butenes in the feed.

[0040] Example 5

[0041] The catalyst, 5 wt% Re2O7 / γ-Al2O3, was prepared by incipient wetness impregnation of the support with a HReO4 solution. Approximately 1.54 g of HReO4 was dissolved in approximately 10.6 ml of DI water. The pore volume of γ-Al2O3 is 0.6, which means that for the incipient wetness method, 0.6 g of water is required per gram of support to evenly disperse the metals. Therefore, the total water required for 19 g of support is 11.4 g. However, the rhenium precursor (HReO4) contributes 0.77 g of water. Therefore, the necessary amount of water to be added for 19 g of support is 10.6 g.

[0042] The impregnation was carried out by contacting about 19 grams of a calcined spherical alumina support with the HReO4 solution at room temperature. The impregnated alumina support was then kept at room temperature for 2 hours and dried at 120°C for 16 hours. The dried alumina support was then calcined in a downflow tubular reactor in the presence of air at 550°C at a heating rate of 5°C / min for 5 hours. After calcination, the catalyst was cooled in the continuous presence of air. The catalyst was stored in a sealed container. The final calculated composition of the catalyst was 5 wt% Re2O7 / Al2O3. The catalyst was tested under conditions similar to those described in Example 2 and the results were given in Table 2. Figure 6 Shown in. Figure 6 is a diagrammatic representation of the isomerization reaction using 5 wt% Re2O7 / γ-Al2O3 under the following reaction conditions: WHSV 0.5 / hr, reaction temperature of about 300°C and 1 atmosphere pressure.

[0043] When a range is disclosed herein, a range from any lower limit can be combined with any upper limit to record an unspecified range, and a range from any lower limit can be combined with any other lower limit to record an unspecified range, and in the same manner, a range from any upper limit can be combined with any other upper limit to record an unspecified range. In addition, even if not explicitly stated, a reference to a value in a range includes each and every value within that range. Thus, each point or individual value can serve as its own lower limit or upper limit, combined with any other point or individual value or any other lower limit or upper limit to record an unspecified range.

[0044] Other objects, features and advantages of the disclosure will become apparent from the above-mentioned drawings, detailed description and examples. Although the specific embodiments of the disclosure are shown, these drawings, detailed description and examples are provided by way of illustration only and are not intended to be restrictive. In other embodiments, features from specific embodiments can be combined with features from other embodiments. For example, features from an embodiment can be combined with any features from other embodiments. In other embodiments, additional features can be added to the specific embodiments described herein. It should be understood that although the disclosure contains some aspects, embodiments and optional features, modifications, improvements or variations of such aspects, embodiments and optional features can be taken by those skilled in the art, and such modifications, improvements or variations are considered to be within the scope of the present disclosure.

Claims

1. A process for the isomerization of olefinic bonds in the presence of a catalyst based on gamma-alumina, the process comprising: heating a gamma-alumina-based catalyst to a temperature in a range of about 450° C. to about 550° C. in an isomerization reactor to produce an activated gamma-alumina-based catalyst, wherein the activated gamma-alumina-based catalyst contains an alkali metal hydroxide in a range of 5 weight percent (wt %) to 10 wt % or rhenium oxide in a range of 3 wt % to 8 wt %; cooling the activated gamma-alumina-based catalyst to a temperature below 450° C.; and An aliphatic light internal olefin-rich stream is supplied to the isomerization reactor to convert a portion of the aliphatic light internal olefin-rich stream into an aliphatic alpha-olefin-rich stream.

2. The process of claim 1, wherein the process is a process for the isomerization of 2-butene to 1-butene, and wherein the activated gamma-alumina-based catalyst has a surface area in the range of about 175-250 m2 / g.

3. The method of claim 1 or claim 2, wherein the alkali metal hydroxide is potassium hydroxide.

4. The process according to any one of claims 1 to 3, wherein the isomerization reactor is a tubular fixed bed reactor.

5. The process according to any one of claims 1 to 3, wherein the activated gamma-alumina based catalyst is cooled in the presence of nitrogen.

6. The process of any one of claims 1 to 3, wherein the aliphatic light internal olefin-rich stream contains greater than 30 wt% 2-butene.

7. A method for preparing a catalyst based on gamma-alumina, the method comprising: calcining the gamma-alumina-based support at a temperature in the range of about 450° C. to about 550° C. to produce a calcined gamma-alumina-based support; treating the calcined gamma-alumina-based support with an aqueous alkali metal hydroxide solution or an aqueous perrhenic acid solution to form an impregnated gamma-alumina-based support; drying the impregnated gamma-alumina-based support at a temperature in the range of about 80°C to about 120°C; and The impregnated alumina support is calcined at a temperature ranging from about 450°C to about 550°C to produce the gamma-alumina based catalyst.

8. The process of claim 7, wherein the calcined gamma-alumina-based support is treated with an aqueous alkali metal hydroxide solution, and wherein the aqueous alkali metal hydroxide solution is sprayed onto the gamma-alumina-based support in a rotary impregnator unit at a gauge pressure of about 1.5 barg to about 4 barg.

9. The process according to any one of claims 7-8, wherein the calcined gamma-alumina-based support is treated with an aqueous alkali metal hydroxide solution, and wherein the amount of alkali metal hydroxide in the gamma-alumina-based catalyst ranges from 5 wt% to 10 wt%.

10. The process of claim 9, wherein the calcined gamma-alumina-based support is treated with an aqueous alkali metal hydroxide solution, and wherein the aqueous alkali metal hydroxide solution contains potassium hydroxide at a molar concentration ranging from about 4 M to about 8 M.

11. The process of any one of claims 7 to 10, wherein the gamma-alumina based support comprises a surface area in the range of about 175 m 2 / g-about 250m 2 / g of γ-alumina based balls.

12. The method of any one of claims 7-12, wherein the gamma-alumina-based support comprises gamma-alumina-based spheres having a pore volume in the range of about 0.5 milliliters per gram (mL / g) to about 0.75 mL / g.

13. The method of claim 7, wherein the calcined gamma-alumina-based support is treated with an aqueous perrhenic acid solution, and wherein the aqueous perrhenic acid solution is sprayed onto the gamma-alumina-based support in the rotary impregnator unit at a gauge pressure of about 2 barg.

14. The process according to any one of claims 7 or 13, wherein the catalyst based on gamma-alumina contains rhenium oxide in the range of 3% to 8% by weight.

15. The process of any one of claims 13-14, wherein the gamma-alumina based support comprises a surface area in the range of about 175 m 2 / g-about 250m 2 / g and gamma-alumina based spheres having a pore volume range of about 0.5 mL / g to about 0.75 mL / g.

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