Oxychlorination Process

Abstract

In a process for producing 1,2-dichloroethane, the process includes the steps of: (i) providing a fluidizable catalyst; (ii) charging a fluidizable catalyst into a fluidized bed reactor; (iii) fluidizing the catalyst in the reactor; (iv) heating the catalyst in the fluidized bed reactor to a temperature greater than 150° C. for more than 6 hours while fluidizing the catalyst in the reactor, wherein the fluidizing and heating steps are performed in the absence of ethylene conversion; and (v) converting ethylene to 1,2-dichloroethane in the presence of the catalyst after the heating step.

Description

[Technical field]

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 300,799, filed January 19, 2022, which is incorporated herein by reference.

[0002] FIELD OF THEINVENTION An embodiment of the present invention provides an oxychlorination process using an activated catalyst.

[0003] 2. Background of the Invention Ethylene dichloride, also called 1,2-dichloroethane (EDC), can be produced by the oxychlorination of ethylene. The oxychlorination process converts ethylene to EDC through a reaction involving hydrochloric acid and oxygen (or an oxygen-containing species). Water is produced as a by-product. Both fixed-bed and fluidized-bed processes are used commercially. Fluidized-bed processes are usually characterized by a more uniform temperature distribution throughout the reactor, since the fluidized bed has excellent transport properties that allow the catalyst to be gradually replaced during operation without the need to shut down the reactor.

[0004] Industrial oxychlorination processes are usually carried out with an excess of ethylene, which serves to minimize unreacted hydrochloric acid (HCl). As those skilled in the art will appreciate, the presence of HCl in the product stream is detrimental as it is not easily removed and can degrade downstream equipment. HCl conversion is also temperature dependent, with higher temperatures resulting in higher HCl conversion. As a result, industrial processes are usually operated at temperatures above 220°C. High temperatures increase the catalytic activity for the oxidation of ethylene to EDC, but unfortunately also promote undesirable side reactions that lead to the generation of CO and CO2, as well as the generation of chlorinated hydrocarbons. In other words, EDC selectivity (a measure of ethylene converted to EDC) decreases with higher concentrations of by-products in the product stream. Among the chlorinated hydrocarbon by-products, 1,1,2-trichloroethane, chloral, ethyl chloride, chloroform and carbon tetrachloride are common and are often oxidized as waste streams. Additionally, heavier chlorinated organic by-products may also be produced that are not easily separated, thus reducing not only the EDC selectivity but also the purity of the product.

[0005] It would therefore be desirable to reduce the operating temperature of any catalyst system without reducing HCl conversion, thereby improving EDC selectivity without a corresponding reduction in process efficiency.

[0006] Summary of the Invention One or more embodiments of the present invention provide a method for producing 1,2-dichloroethane comprising the steps of: (i) providing a fluidizable catalyst; (ii) charging a fluidizable catalyst to a fluidized bed reactor; (iii) fluidizing the catalyst in the reactor; (iv) heating the catalyst in the fluidized bed reactor to a temperature greater than 150° C. for more than six hours while fluidizing the catalyst in the reactor, wherein the fluidizing and heating steps are performed in the absence of ethylene conversion; and (v) converting ethylene to 1,2-dichloroethane in the presence of the catalyst after the heating step.

[0007] DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS The embodiments of the present invention are based, at least in part, on the discovery of an oxychlorination process carried out in a fluidized bed in the presence of an activated catalyst. According to an aspect of the present invention, the catalyst is activated before converting ethylene to 1,2-dichloroethane. In one or more embodiments, activation generally involves heating the catalyst for a sufficient time under fluidized conditions without ethylene conversion. It has been observed that activating the catalyst increases the amount of ethylene converted to 1,2-dichloroethane (i.e., EDC selectivity) relative to other conversion products without adversely affecting process efficiency. In other words, activating the catalyst allows for efficient production of 1,2-dichloroethane while producing less undesirable by-products.

[0008] Process overview and reactor configuration In one or more embodiments, the oxychlorination process of the present invention is carried out in a fluidized bed reactor, which is a reactor adapted to hold and fluidize a catalyst. Fluidized bed reactors and methods for their use in the oxychlorination of ethylene to 1,2-dichloroethane (EDC) are generally known, as disclosed in U.S. Pat. No. 5,292,703, and U.S. Patent Application Publication Nos. 2009 / 0054708, 2009 / 0298682, 2010 / 0274061, 2006 / 0129008, and 2004 / 0192978, which are incorporated herein by reference. In one or more embodiments, the fluidized bed reactor comprises a reaction zone in which the conversion of ethylene to EDC takes place. In one or more embodiments, the reactor is equipped with temperature control elements, such as steam coils, which can be used to heat or cool the reactor, particularly the reaction zone.

[0009] In one or more embodiments, at least a portion of the fluidized bed reactor comprises a fluidizable catalyst composition. The catalyst composition may simply be referred to as a catalyst and comprises a catalytic material impregnated on a solid support. The catalytic material, which is typically a catalytic metal compound, and the solid support are described in more detail below.

[0010] In one or more embodiments, ethylene, hydrochloric acid, oxygen gas and / or oxygen-containing species, and optionally an inert gas are fed to the reactor as one or more fluid streams. These fluid streams may be injected into the reactor under conditions such as force and / or velocity to fluidize the catalyst composition within the bed. In other words, as one skilled in the art will understand, the fluid streams pass through the reactor (e.g., reaction zone) to suspend, mix, and behave in a manner similar to a fluid, the catalyst composition. In one or more embodiments, the reactants and / or gas feeds are fed to the bottom of the reactor and pass through one or more distribution elements into the reaction zone. In one or more embodiments, the product stream, including EDC, ethylene by-product, water, unreacted reactants, and optionally an inert gas, exits the reactor through an outlet port located at or near the top of the reactor.

[0011] In one or more embodiments, the reactor is configured for a once-through process, where unreacted ethylene in the product stream is vented or otherwise removed. Alternatively, the reactor is configured for a recycle process, where unreacted ethylene is recycled to the reactor. In one or more embodiments, the product stream undergoes separation to separate non-condensable components, liquid organics, and water-soluble compounds. For example, the product stream may be directed to a quench system that condenses the EDC and hydrochloric acid to form a gaseous non-condensable stream and a liquid stream. The liquid stream may undergo liquid-liquid separation to isolate the EDC from the aqueous components. The non-condensable stream, which may include ethylene, oxygen, and nitrogen, as well as other gaseous components, may be recycled to the reactor.

[0012] catalyst composition As mentioned above, the catalyst, which may be called catalyst composition or catalyst particle, includes a support impregnated with a catalytic metal compound; that is, a support on which the catalytic metal compound is deposited. In one or more embodiments, the catalytic metal compound includes a copper compound, optionally together with one or more complementary catalytic metal compounds, which may be called promoters. Catalysts useful for oxychlorination are generally known, for example, as described in US Patent Publication No. 2014 / 0128643 and US Patent No. 5,292,703, which are incorporated herein by reference.

[0013] Support material In one or more embodiments, the support, which is generally a fluidizable high surface area support material, can be prepared from silica, magnesia, diatomaceous earth, clay, fuller's earth, alumina, zeolite, or combinations thereof. According to one or more embodiments, the support can be a high surface area powder (e.g., gamma, delta, or theta alumina powder) including particles, granules, and / or spheres (e.g., alumina microspheres or nanospheres in amorphous or colloidal form). In embodiments, the alumina support can be an activated alumina or transition alumina produced by calcination of a hydrated or hydroxylated precursor alumina. These activated aluminas can be identified by an ordered structure observable by X-ray diffraction patterns, which show that the mixed phase material contains minimal or no low surface area or crystalline phase alpha alumina.

[0014] Those skilled in the art recognize that alpha alumina can be identified by the crystalline phases defined by X-ray diffraction. Higher surface area activated alumina is often defined as gamma alumina phase, but the phase transition may be a continuum with varying percentages of mixed phases, including but not limited to delta and theta phases, based on the calcination temperature selected to obtain the desired support surface area. In certain embodiments, gamma alumina is used as the support. The alumina support (e.g., gamma alumina powder) may be referred to as a fluidizable alumina support or a fluidizable alumina support material.

[0015] In one or more embodiments, useful gamma alumina supports are powders having at least 90%, or at least 95%, or at least 98%, or at least 99%, or at least 99.995% gamma phase. In these or other embodiments, useful gamma alumina supports are powders having at least about 50% gamma phase. 2 / g ~ approx. 250m 2 / g, or about 70m 2 / g ~ approx. 225m 2 / g, or about 100m 2 / g ~ approx. 215m 2 / g, or about 150m 2 / g ~ approx. 205m 2 According to embodiments, useful alumina supports (e.g., gamma alumina powders) have a surface area of ​​at least 80 m 2 In these or other embodiments, useful fluidizable alumina supports have a surface area of ​​about 0.5 g / cm 3 ~Approx. 4.0g / cm 3 , or about 0.75 g / cm 3 ~Approx. 3.0cm 3 , or about 1.0 cm 3 ~Approx. 2.0cm 3 , or about 0.7 cm 3 ~approx. 1.3cm 3 , or about 3.65 cm 3 In these or other embodiments, useful alumina support materials may have a compacted bulk density of about 0.1 cm 3 / g ~ approx. 2cm 3 / g, or about 0.2 cm 3 / g ~ approx. 1cm 3 / g, or about 0.3 cm 3 / g ~ approx. 0.75cm 3In these or other embodiments, the fluidizable alumina support material may have a particle size distribution as measured by a Fraunhofer Laser Diffraction (i.e., light scattering) analyzer manufactured by Malvern Instruments, Ltd., as follows: (a) about 90 to about 100 volume percent of the particles are less than about 150 μm, or less than about 140 μm, or less than about 125 μm, or less than about 110 μm in diameter; (b) about 50 to about 60 volume percent of the particles are less than about 75 μm, or less than about 70 μm, or less than about 65 μm, or less than about 60 μm; and (c) about 90 to about 100 volume percent of the particles are less than about 150 μm, or less than about 140 μm, or less than about 125 μm, or less than about 110 μm in diameter. About 20 to about 35 volume percent of the particles are less than about 45 μm, or less than about 40 μm, or less than about 35 μm, or less than about 30 μm, where a 5 g sample of the material is dispersed in 100 mL of deionized water using a magnetic stirrer for 1 minute at room temperature (about 20° C. to about 25° C.) and pressure (about 1 atmosphere) to form a suspension, and 4 mL of the suspension is diluted with 130 mL of deionized water and analyzed using an analyzer at 2500 revolutions per minute (at room temperature and pressure).

[0016] Useful alumina supports are commercially available. For example, useful supports can be obtained under the trade names Puralox® SCCa-57 / 170 and Catalox® SCCa-25 / 200 (Sasol). These aluminas are high purity activated aluminas that are easily fluidizable, relatively stable, mechanically strong, and wear resistant.

[0017] In some non-limiting embodiments, the alumina support may contain additional components. Examples of these additional components include, but are not limited to, lanthanum (La), cerium (Ce), titanium (Ti), silicon (Si), and the like, as minor components dispersed throughout the alumina support prior to impregnation with the active catalyst formulation. For example, the alumina support may include from about 0.005% to about 0.50% by weight of one or more additional components.

[0018] It is also recognized that some alumina support materials, in addition to aluminum oxide (Al2O3) (and additional components), may contain small amounts of other metallic impurities such as metal oxides, e.g., less than about 0.02 wt.% sodium oxide, less than about 0.05 wt.% iron oxide (Fe2O3), less than about 0.3 wt.% titanium dioxide, less than about 0.2 wt.% silicon dioxide, etc. It is also known that Ti compounds may remain in the alumina from the alumina manufacturing process.

[0019] Catalyst Materials As described above, the catalytic composition typically includes one or more metal compounds. In one or more embodiments, the metal compound includes a copper compound in combination with one or more complementary metal compounds (i.e., promoters). For example, in one or more embodiments, the metal compound, which may be referred to as a catalytic metal compound, may include a copper compound, an alkaline earth metal compound (e.g., a magnesium compound), optionally an alkali metal compound (e.g., a potassium compound), and a transition metal compound (e.g., a manganese compound or a rhenium compound). Other exemplary catalytic metal compound combinations include a copper compound, an alkaline earth metal compound (e.g., a magnesium compound), optionally an alkali metal compound (e.g., a potassium compound), and a rare earth metal compound (e.g., a lanthanum compound). Still other exemplary catalytic metal compound combinations include a copper compound, an alkaline earth metal compound (e.g., a magnesium compound), and optionally an alkali metal compound (e.g., a potassium compound). Other exemplary catalytic metal compound combinations include a copper compound, an alkaline earth metal compound (e.g., a magnesium compound), optionally an alkali metal compound (e.g., a potassium compound), and a zirconium compound (e.g., zirconium oxychloride).

[0020] In one or more embodiments, the copper compound is a water-soluble salt, such as copper chloride (e.g., copper II chloride). Other copper salts that can be converted to chloride during the oxychlorination process can also be used, such as nitrates, carbonates, sulfates, or other halide salts, such as bromides, or combinations thereof.

[0021] In one or more embodiments, useful alkali metal compounds include water-soluble salts such as alkali metal chlorides. Other alkali metal salts that can be converted to chloride salts during the oxychlorination process can also be used, such as other halide salts, such as nitrates, carbonates, sulfates, or bromides, or combinations thereof. In certain embodiments, the alkali metal compound includes potassium salts, such as potassium chloride, potassium nitrate, potassium bromate, potassium carbonate, or potassium sulfate. In certain embodiments, the alkali metal compound is potassium chloride. In one or more embodiments, the alkali metal compound may include potassium chloride and one or more additional alkali metal compounds, such as lithium chloride. In other embodiments, the catalytic metal compound includes potassium compounds and does not include or includes only trace amounts (e.g., less than 1 ppm by weight) of other alkali metal compounds.

[0022] In one or more embodiments, useful alkaline earth metal compounds include water-soluble salts such as alkaline earth metal chlorides. Other alkaline earth metal salts that can be converted to chloride salts during the oxychlorination process can also be used, such as other halide salts, such as nitrates, carbonates, sulfates, or bromides, or combinations thereof. In certain embodiments, the alkaline earth metal compound includes magnesium salts, such as magnesium chloride, magnesium nitrate, magnesium bromate, magnesium carbonate, or magnesium sulfate. In certain embodiments, the alkaline earth metal compound is magnesium chloride. In one or more embodiments, the alkaline earth metal compound can include a magnesium compound and one or more additional alkaline earth metal compounds, such as compounds of calcium, strontium, barium, or mixtures thereof. In certain embodiments, the catalytic metal compound includes a magnesium compound and does not include or includes only trace amounts (e.g., less than 1 ppm by weight) of other alkaline earth metal compounds.

[0023] In one or more embodiments, useful transition metal compounds include water-soluble salts such as transition metal chlorides (e.g., chlorides or oxychlorides). Other salts that can be converted to chloride salts during the oxychlorination process can also be used, such as other halide salts, such as nitrates, carbonates, sulfates, or bromides, or combinations thereof. Useful transition metal compounds include manganese compounds, such as manganese chloride, and / or rhenium compounds. Still other useful transition metal compounds include zirconium compounds, such as zirconium oxychloride. In one or more embodiments, the catalytic metal compound can include a transition metal compound in combination with one or more additional transition metal compounds. In other embodiments, the catalytic metal compound includes a transition metal compound (e.g., zirconium oxychloride) and does not include or includes only trace amounts (e.g., less than 0.005 wt %) of other transition metal compounds. In one or more embodiments, the catalytic metal compound includes zirconium and does not include manganese (Mn) or rhenium (Re).

[0024] In one or more embodiments, useful rare earth metal compounds include water-soluble salts such as rare earth metal halides (e.g., chlorides). Other salts that can be converted to chloride salts during the oxychlorination process can also be used, such as other halide salts, such as nitrates, carbonates, sulfates, or bromides. Useful rare earth metal compounds include lanthanum compounds, such as lanthanum chloride. Other useful rare earth metal compounds include cerium compounds, neodymium compounds, and praseodymium compounds. In one or more embodiments, the catalytic metal compound can include a rare earth metal compound in combination with one or more additional rare earth metal compounds. In other embodiments, the catalytic metal compound includes one rare earth metal compound and no or only trace amounts (e.g., less than 0.005 wt.%) of other rare earth metal compounds. In one or more embodiments, the catalytic metal compound includes a lanthanide metal and does not contain manganese (Mn) or rhenium (Re).

[0025] Catalytic metal loading As one of ordinary skill in the art will appreciate, the amount of copper metal deposited will generally be based on the desired activity and the particular fluidization properties of the support for fluidized bed catalyst applications. In one or more embodiments, the catalyst composition comprises from about 1 wt. % to about 10 wt. % copper metal, based on the total weight of the catalyst composition. In one or more embodiments, the catalyst comprises greater than 2.0 wt. % copper (atomic copper), based on the total weight of the catalyst, or greater than 3.0 wt. % in other embodiments. In these or other embodiments, the catalyst comprises less than 6.0 wt. % copper, based on the total weight of the catalyst, or less than 8.0 wt. % in other embodiments, or less than 10 wt. % copper.

[0026] When the catalyst includes an alkali metal compound, the catalyst composition may include from about 0.5 wt.% to about 5.0 wt.%, or from about 0.75 wt.% to about 4.0 wt.%, or from about 1.0 wt.% to about 3.0 wt.% of an alkali metal (e.g., atomic potassium), based on the total weight of the catalyst composition. In one or more embodiments, the catalyst includes greater than 0.5 wt.%, or in other embodiments greater than 0.75 wt.%, of an alkali metal, based on the total weight of the catalyst. In one or more embodiments, the catalyst includes less than 5.0 wt.%, or less than 4.0 wt.%, or less than 3.0 wt.% of an alkali metal (e.g., potassium metal), based on the total weight of the catalyst composition. When an additional alkali metal is included, the catalyst may contain from about 0.005 wt.% to about 10.0 wt.% of the additional alkali metal.

[0027] When the catalyst includes an alkaline earth metal compound, the catalyst composition may include from about 0.5 wt.% to about 5.0 wt.%, or from about 0.75 wt.% to about 4.0 wt.%, or from about 1.0 wt.% to about 3.0 wt.% of an alkaline earth metal (e.g., atomic magnesium), based on the total weight of the catalyst composition. In one or more embodiments, the catalyst includes greater than 0.5 wt.%, or in other embodiments greater than 0.75 wt.%, of an alkaline earth metal, based on the total weight of the catalyst. In one or more embodiments, the catalyst includes less than 5.0 wt.%, or less than 4.0 wt.%, or less than 3.0 wt.% of an alkaline earth metal (e.g., magnesium), based on the total weight of the catalyst composition. When additional alkaline earth metal is included, the catalyst may contain from about 0.005 wt.% to about 10.0 wt.% of the additional alkaline earth metal.

[0028] When the catalyst includes a transition metal compound, the catalyst composition may include from about 0.1 wt. % to about 3.0 wt. %, or from about 0.3 wt. % to about 2.5 wt. %, or from about 0.5 wt. % to about 2.0 wt. % of the transition metal (e.g., atomic manganese), based on the total weight of the catalyst composition. In one or more embodiments, the catalyst includes greater than 0.1 wt. %, or in other embodiments, greater than 0.3 wt. %, of the transition metal, based on the total weight of the catalyst composition. In one or more embodiments, the catalyst includes less than 3.0 wt. %, or less than 4.0 wt. %, or less than 2.0 wt. % of the transition metal (e.g., manganese metal), based on the total weight of the catalyst composition. When an additional transition metal is included, the catalyst may contain from about 0.005 wt. % to about 10.0 wt. % of the additional transition metal.

[0029] When the catalyst includes a rare earth metal compound, the catalyst composition may include from about 0.1 wt. % to about 3.0 wt. %, or from about 0.3 wt. % to about 2.5 wt. %, or from about 0.5 wt. % to about 2.0 wt. % of a rare earth metal (e.g., atomic lanthanum), based on the total weight of the catalyst composition. In one or more embodiments, the catalyst includes more than 0.1 wt. %, or in other embodiments more than 0.3 wt. %, of a rare earth metal, based on the total weight of the catalyst. In one or more embodiments, the catalyst includes less than 3.0 wt. %, or less than 4.0 wt. %, or less than 2.0 wt. % of a rare earth metal (e.g., atomic lanthanum), based on the total weight of the catalyst composition. In one or more embodiments, additional rare earth metals may be included, and the catalyst may contain from about 0.005 wt. % to about 10.0 wt. % of an additional transition metal.

[0030] In certain embodiments, the catalyst comprises a zirconium salt, such as zirconium oxychloride, zirconium carbonate, or zirconium hydroxide. The catalyst may comprise zirconium as metal in the range of about 0.1 wt.% to about 3.0 wt.%, or about 0.5 wt.% to about 2.0 wt.%, or about 0.75 wt.% to about 1.0 wt.%, based on the total weight of the catalyst composition. According to embodiments, the catalyst may comprise metallic zirconium in an amount less than 3.0 wt.%, or less than 2.0 wt.%, or less than 1.0 wt.%, based on the total weight of the catalyst composition. If an additional transition metal is included, the catalyst may contain about 0.005 wt.% to about 10.0 wt.% of the additional transition metal.

[0031] As one skilled in the art will appreciate, the final catalyst composition containing the catalytic metals (e.g., copper compounds, alkaline earth metal compounds, and transition metal compounds) is easily fluidizable. In one or more embodiments, other optional metals may be present in relatively small or trace amounts in the catalyst composition. Typically, these metals, if present, may be present in an amount less than about 0.005 wt.%, based on the total weight of the catalyst composition.

[0032] Preparation of the Catalyst Composition The catalysts used in the present invention may be prepared by conventional techniques.

[0033] For example, the metal compounds can be impregnated into an alumina support. This can be accomplished by introducing an aqueous solution of a water-soluble salt (i.e., metal compound) into the support. The wetted support can then be dried and optionally calcined. The support can be impregnated with the metal compounds by using a single solution, or in other embodiments, multiple solutions can be used in succession. For example, the alkaline earth metal compound, the transition metal compound, and any additional metal compounds can be introduced first (optionally dried and calcined), and then the copper compound can be introduced into the support previously impregnated with the other metal compounds. In this regard, U.S. Patent Application Publication No. 2014 / 0275661 and U.S. Patent Application Publication No. 2017 / 0137351 are incorporated herein by reference.

[0034] As one skilled in the art will appreciate, the impregnation solution can be prepared by dissolving the desired amount of metal salt in water with stirring (e.g., hand stirring or vigorous mixing) at room temperature or optionally at elevated temperatures (e.g., about 40°C to about 60°C). Once dissolved, the metal salt solution can be introduced into the alumina support (i.e., impregnating the support). For example, the solution can be slowly introduced into a tumbler (e.g., rotating at about 90 revolutions per minute) containing the support. The salt solution is dripped or sprayed onto the support within 30 minutes. After impregnation, the wet catalyst is typically dried. This may include pre-drying, which can be done by heating the catalyst in a steam bath (e.g., the catalyst in a ceramic dish or other container can be optionally heated in a steam bath for about 1 to about 3 hours). With or without pre-drying, the catalyst can be heated in an oven to drive off all or substantially all of the water. For example, the catalyst can be heated in an oven having an ambient temperature of about 100°C to about 180°C, or about 110°C to about 150°C, or about 100°C, or about 105°C, or about 110°C, or about 115°C. During this heating step, the catalyst can be exposed to these elevated temperatures for about 2 hours to about 30 hours, or about 10 hours to about 28 hours, or about 20 hours to about 25 hours. After drying, the dried catalyst can be sieved (e.g., hot sieved) using, for example, a 500 μm sieve, or a 475 μm sieve, or a 450 μm sieve, or a 400 μm sieve, or a 350 μm sieve, or a 300 μm sieve. The dried catalyst can be hot sieved at a temperature of about 100°C to about 200°C, or at a temperature of 130°C. The final catalyst material can be packaged (eg, bottled).

[0035] Those skilled in the art will appreciate that certain properties of the catalyst, such as surface area and pore volume, may be altered by deposition of metal salts. For example, the catalyst compositions described herein may have a surface area of ​​about 20 to about 220 m. 2 / g, or about 60 to about 180 m 2 / g, or about 70 to about 170 m 2 / g, or about 80m 2 / g~about 150m 2 / g, or about 150m 2 / g ~ approx. 215m 2 The resulting surface area can range from 100 μm to 100 μm / g.

[0036] Catalyst activation As mentioned above, the catalyst compositions described herein can be activated. In one or more embodiments, the catalyst is activated in a reactor bed while being heated and fluidized with a fluidizing gas comprising one or more of air, oxygen-enriched air, nitrogen-enriched air, nitrogen, and combinations thereof.

[0037] When carrying out the method of one or more embodiments of the present invention, the catalyst is placed in a reactor (i.e., a fluidized bed reactor), and this step can be referred to as charging the catalyst to the reactor. After the catalyst is charged to the reactor, activation of the catalyst is performed. In one or more embodiments, activation of the catalyst includes heating the catalyst under fluidized conditions (i.e., while the catalyst is fluidized) such that the catalyst composition reaches a threshold temperature for a threshold amount of time. In one or more embodiments, the catalyst is heated to a temperature greater than 150°C, in other embodiments greater than 170°C, in other embodiments greater than 190°C, and in other embodiments greater than 210°C. In these embodiments, the temperature of the catalyst is maintained (under fluidized conditions) for greater than 6 hours, in other embodiments greater than 12 hours, in other embodiments greater than 24 hours, and in other embodiments greater than 36 hours.

[0038] As stated above, activation is carried out in the substantial absence of ethylene conversion or EDC production. According to aspects of the invention, activation of the catalyst is carried out in the substantial absence of hydrochloric acid, but not more than an amount that would appreciably affect the practice of the invention. In one or more embodiments, activation of the catalyst is carried out in the presence of less than 100 ppm, in other embodiments less than 50 ppm, and in other embodiments less than 25 ppm hydrochloric acid. In these or other embodiments, activation of the catalyst is carried out in the substantial absence of ethylene, but not more than an amount that would appreciably affect the practice of the invention. In one or more embodiments, activation of the catalyst is carried out in the presence of less than 100 ppm, in other embodiments less than 50 ppm, and in other embodiments less than 25 ppm ethylene.

[0039] In one or more embodiments, activation of the catalyst occurs while the catalyst is fluidized in the presence of a fluidization gas stream that comprises oxygen gas or an oxygen-containing gas. In these or other embodiments, activation of the catalyst occurs while the catalyst is fluidized in the presence of a fluidization gas stream that comprises an inert gas, such as argon or nitrogen. In certain embodiments, activation of the catalyst occurs while the catalyst is fluidized in the presence of a fluidization gas stream that comprises an inert gas and is substantially free of oxygen or an oxygen-containing gas.

[0040] As one skilled in the art will appreciate, the catalyst can be heated in the reactor using conventional techniques that can be influenced through a reactor temperature control element, such as a coil or tube containing a heat transfer fluid. In the reactor, the temperature of the catalyst can be determined by one or more thermocouples placed in a thermal well located in the fluidized bed, which is in contact with the fluidized mass. For the purposes of these measurements according to embodiments herein, the fluidized bed is assumed to be equilibrated at a macro level, and therefore the temperature of the fluidized mass (including gas and solid phases) at the location of the thermal well is assumed to be the same as or close to the temperature of the catalyst composition (i.e., particles). Similarly, the catalyst can be fluidized using conventional techniques that can be influenced by injecting a pressurized gas stream into the reactor, with conditions adapted to fluidize the catalyst.

[0041] In one or more embodiments, the oxychlorination process is started after activation of the catalyst in the reactor, but before any deleterious changes in the catalyst properties. As the skilled artisan will appreciate, the initiation of the oxychlorination process is performed by feeding ethylene, hydrochloric acid, and oxygen or oxygen-containing species to the reactor (i.e., the reactant feed is fed to the reactor). In one or more embodiments, the reactant feed is fed to the reactor without stopping the fluidization of the catalyst. In these or other embodiments, the reactant feed is fed to the reactor at a temperature above 50° C., in other embodiments above 35° C., in other embodiments above 20° C., and in other embodiments above 10° C., before the catalyst is cooled (after activation). In these or other embodiments, the reactant feed is fed to the reactor before the catalyst is cooled to a temperature below 110° C., in other embodiments below 120° C., in other embodiments below 130° C., and in other embodiments below 140° C.

[0042] In one or more embodiments, the activation of the catalyst is performed before the catalyst is used in an oxychlorination process. In other embodiments, the activation of the catalyst is performed after its use in an oxychlorination process. For example, an oxychlorination process using a particular catalyst is paused and the catalyst is activated according to the present invention. In one or more embodiments, the reaction is paused by stopping at least the hydrochloric acid feed. In other embodiments, the reaction is paused by stopping both the hydrochloric acid feed and the ethylene feed.

[0043] Without being bound to a particular theory, it is believed that the activation of the catalyst according to the present invention removes excess water of hydration and some chlorine, e.g., hydrochloric acid, from the catalyst. Thus, this activation process may also modify the surface chemistry of the catalyst, making it more effective in certain applications. Although in embodiments of the present invention it is necessary to fluidize the catalyst during activation and maintain the heat and fluidization conditions until the oxychlorination process is started, it is believed that the activation of the catalyst could possibly be performed outside the reactor, so long as the catalyst is maintained in a water-free environment until the oxychlorination process is started. For example, it is believed that the benefits of the present invention can be obtained if the activated catalyst is maintained under anaerobic conditions, such as nitrogen purging or nitrogen blanketing, during storage, transportation, and loading into the reactor. It is also believed that the benefits of the present invention can be obtained if the catalyst is maintained at a threshold temperature during storage, transportation, and loading into the reactor.

[0044] Oxychlorination Process The catalyst composition of the present invention is a highly efficient catalyst for the oxychlorination of ethylene to EDC. The reaction process temperature is from about 170°C to about 260°C, in other embodiments from about 180°C to about 250°C, and in other embodiments from about 190°C to about 240°C. The reaction pressure varies from atmospheric pressure to as high as about 200 psig. The contact time in the fluidized bed catalyst and fixed bed catalyst can be from about 5 seconds to about 50 seconds (contact time is defined herein as the ratio of the reactor volume taken up by the catalyst to the volumetric flow rate of the feed gas at the reactor control temperature and maximum pressure), and in other embodiments from about 5 seconds to about 35 seconds. The ratio of ethylene, HCl and oxygen reactants, based on the moles of HCl fed to the reactor, can range from about 1.0 to about 2.0 moles of ethylene and about 0.5 to about 0.9 moles of oxygen per 2.0 moles of HCl. As mentioned above, modern oxychlorination processes attempt to operate within a stoichiometric ratio range of about 1 to about 2 moles of HCl per mole of ethylene.

[0045] As mentioned above, the oxychlorination process of the present invention converts ethylene to 1,2-dichloroethane (EDC) in the presence of an activated catalyst. Typically, the reaction proceeds in the presence of 2 moles of hydrochloric acid and 1 / 2 mole of oxygen to produce EDC and water. In one or more embodiments, the oxychlorination catalyst of the present invention can be advantageously used in oxychlorination processes where the molar ratio of oxygen to hydrogen chloride (O2 / 2HCl) approaches a stoichiometric feed rate of 0.5. In one or more embodiments, the process operates at a molar ratio of oxygen to hydrogen chloride (O2 / 2HCl) of less than 0.9, in other embodiments less than 0.64, in other embodiments less than 0.58, in other embodiments less than 0.55, and in other embodiments less than 0.52. In one or more embodiments, the process operates at a molar ratio of oxygen to hydrogen chloride (O2 / 2HCl) of from about 0.50 to about 0.80, from about 0.51 to about 0.70 in other embodiments, from about 0.52 to about 0.60 in other embodiments, and from about 0.53 to about 0.58 in other embodiments.

[0046] In those embodiments in which a recycle is implemented, the ratio of HCl to ethylene may be less than 2. In those embodiments in which a once-through process is implemented, the ratio of HCl to ethylene may be higher and may approach or be closer to 2, resulting in an overall HCl to ethylene molar operating range of about 1 to about 2.

[0047] The oxychlorination processes described herein can be operated at or above conventional operating temperatures, such as 220° C. In other embodiments, the oxychlorination processes can be operated at temperatures below 218° C., below 215° C. in other embodiments, or below 212° C. in other embodiments. In one or more embodiments, the oxychlorination processes of the present invention are carried out at temperatures between about 180° C. and 220° C., between about 190° C. and about 218° C. in other embodiments, between about 195° C. and about 215° C. in other embodiments, and between about 200° C. and about 210° C. in other embodiments.

[0048] In these or other embodiments, the reaction pressure may vary from about atmospheric pressure to as high as about 200 psig. The contact time in the fluidized and fixed bed catalysts is from about 10 seconds to about 50 seconds (contact time is defined as the ratio of the reactor volume taken up by the catalyst to the volumetric flow rate of the feed gas at the reactor control temperature and maximum pressure), and may be from about 20 seconds to about 35 seconds. The ratio of ethylene, HCl and oxygen reactants, based on the moles of HCl fed to the reactor, may range from about 1.0 mole to about 2.0 moles of ethylene and about 0.5 moles to about 0.9 moles of oxygen per 2.0 moles of HCl. Typical oxychlorination processes attempt to operate within a stoichiometric ratio range of about 1 mole to about 2 moles of HCl per mole of ethylene.

[0049] Process Features The process of the present invention advantageously provides efficient conversion of ethylene to EDC. As one skilled in the art will appreciate, conversion to EDC can be measured by conversion of hydrochloric acid. According to aspects of the present invention, activation of the catalyst according to embodiments described herein results in an improvement in EDC yield of more than 0.1%, in other embodiments, an improvement in EDC yield of more than 0.25%, in other embodiments, an improvement in EDC yield of more than 0.5%, and in other embodiments, an improvement in EDC yield of more than 0.75%, when the oxychlorination is carried out at a temperature of about 200° C. to 220° C. In other embodiments, activation of the catalyst according to embodiments described herein results in an improvement in EDC yield of more than 1.0%, in other embodiments, an improvement in EDC yield of more than 1.25%, in other embodiments, an improvement in EDC yield of more than 1.5%, and in other embodiments, an improvement in EDC yield of more than 2.0%, when the oxychlorination is carried out at a temperature of about 200° C. to 220° C.

[0050] Working Example In order to demonstrate the practice of the present invention, the following examples have been prepared and tested. However, the examples should not be construed as limiting the scope of the invention. The claims will serve to define the invention.

[0051] A series of sequential laboratory-scale oxychlorination reactions (i.e., runs) were conducted. The equipment and procedures used for each run were generally identical, except as outlined below. Similarly, each catalyst was similarly prepared, except as noted below.

[0052] The catalyst used in each run was prepared by impregnating an alumina support with a catalyst impregnation solution. The alumina support was available under the trade name SCCa 25 / 200 (Sasol), with a pore volume of 0.44 mL / g and a pore size of 203 m. 2 The particle size distribution (psd) of the support was characterized in that 1.4% of the particles were smaller than 22 microns, 7.1% of the particles were smaller than 31 microns, 23% of the particles were smaller than 44 microns, 79% were smaller than 88 microns, and 94% were smaller than 125 microns.

[0053] The catalyst impregnation solution was prepared by dissolving the metal chlorides in water, and then the solution was distributed evenly throughout the support. The volume of the solution was chosen to match 95% + / - 3% of the pore volume of the support. The impregnated catalyst was then dried at temperatures up to 150°C to remove most of the water, and then further oven dried at 110°C for 16 hours. The metals used, as well as the amount of each metal used in each run, are shown in the table below. For clarity, the metals are listed in weight percent, which represents the weight of each metal relative to the entire catalyst composition (e.g., the weight percent of copper as the metal relative to the total weight of the catalyst composition, including the total weight of all metal chlorides and the support).

[0054] Multiple reactors were used, each with an internal diameter of about 2 cm and packed with catalyst such that the bed height was about 99 + / - 2.5 cm. The reactors were equipped with a thermocouple located in the center of the fluidized bed and an external electric heater to maintain the reaction temperature at the desired temperature. Each reactor was configured to communicate with an analyzer adapted to measure HCl in the feed and product streams, as well as N2, C2H4, O2, COx, and chlorinated hydrocarbons in the product streams. Specifically, HCl in the feed and product gases was measured by titration, and N2, C2H4, O2, COx, and chlorinated hydrocarbons were measured by GC (HP 6890 series; column type--1) Vocol glass capillary column (60 meters; internal diameter 0.75 mm; film thickness 1.5 microns; 2) 80 / 100 Porapak N column (12 x 1 / 8 inch, stainless steel). 3) 60 / 80 molecular sieve, 5 Angstroms (6 feet x 1 / 8 inch); Detectors--2 TCDs. Detector B (Vocol column) is measured by Detector A (molecular sieve / Porapak); the first TCD is used to detect light gases such as O2, N2, and CO from the molecular sieve column and heavy gases such as CO2 and ethylene from the Porapak column, as well as light chlorinated hydrocarbons such as vinyl chloride and ethyl chloride. The second TCD is used to detect the remaining heavy chlorinated hydrocarbons, including chloroform and other heavy chlorinated by-products, from the Vocol column.

[0055] During the oxychlorination, the reactor was operated at atmospheric pressure over a series of temperatures with a feed gas flow consisting of 11.4 NL / h N2, 3.75 NL / h ethylene, 7.12 NL / h HCl, and 2.55 NL / h O2, unless otherwise specified in the table below. Data was collected over a series of temperatures and interpolated over the temperature range. Specifically, after the reaction conditions were equilibrated at a given set temperature, data was collected on EDC selectivity (moles of ethylene converted to EDC relative to the total moles of ethylene converted) and HCl conversion. The reaction temperature was then increased (typically about 3-5°C), equilibrated, and data on EDC selectivity and HCl conversion were again collected. Once the data was interpolated, reactions were compared (based on HCl conversion) at the same performance levels of 98% and 97% selectivity of ethylene to EDC. These comparisons are shown in the table below.

[0056] In connection with the present invention, runs were carried out with and without catalyst activation. In general, the activated catalyst was fluidized at high temperature with a feed gas stream consisting of nitrogen and oxygen (unless otherwise specified) in the ratios and times specified in the table below. In the non-activated runs, the column was packed with catalyst and the reactor was fluidized with nitrogen and brought to a temperature of about 200° C. Within about 2 hours of reaching the target temperature, the feeds of ethylene, oxygen and HCl were started and the oxychlorination reaction was allowed to proceed.

[0057] For an unactivated catalyst, runs are conducted at higher temperatures and lower HCl conversion to achieve the same EDC selectivity as the activated catalyst. Activation is demonstrated when the catalyst exhibits higher HCl conversion at a lower operating temperature and achieves the same EDC selectivity. An unactivated catalyst needs to be run at a higher temperature to improve overall performance and achieve the same HCl conversion as the activated catalyst, but this results in a lower selectivity to EDC.

[0058] Dataset I - Runs 1 to 6 The first data set, summarized in Table I below, generally shows the combined effect of catalyst activation and catalyst metal ratio.

[0059] As shown in Table I, runs 1 and 2, runs 3 and 4, and runs 5 and 6 respectively used the same catalyst, with runs 1, 3, and 5 not activated, while runs 2, 4, and 6 were activated according to the present invention. Comparing run 2 to run 1, it can be seen that activating the catalyst allows for higher HCl conversion at lower temperatures with the same EDC selectivity. Similar results are also shown when comparing run 4 (activated) to run 3 (non-activated) and run 6 (activated) to run 5 (non-activated). The data also shows a general trend that lower copper loadings generally require higher temperatures to achieve the desired selectivity, but the advantage of the present invention is maintained in that the activation of the catalyst allows for lower temperatures while still achieving the desired HCl conversion and EDC selectivity for each catalyst. Finally, the data shows that activation can be achieved with or without oxygen in the feed stream during activation; run 6 was activated with only a nitrogen feed and achieved results comparable to activations that occurred in the presence of a nitrogen and oxygen blend. [Table 1]

[0060] Dataset II - Runs 7-8 A second data set, summarized in Table II below, shows that the reactor run time does not produce the same results as catalyst activation: for Run 7, data was collected after the reactor had been run for about 50 days (under oxychlorination conditions) at various temperatures (with sporadic room temperature nitrogen fluidization for about 16 days with HCl and ethylene feeds turned off). Despite this extended run, Run 7 did not achieve the advantages seen in Run 8, which was activated according to the invention (as evidenced by the similar achievement of higher HCl conversion at the targeted EDC selectivity at lower temperatures). [Table 2]

[0061] Dataset III - Runs 9-12 A third data set, summarized in Table III below, shows that catalyst activation is a function of time and temperature. Each run represents data sets collected consecutively from the same reactor (i.e., after the reactor was operated and data was collected for the previous run). Specifically, in run 9, the catalyst was fluidized with a nitrogen / oxygen blend at 200° C. for about 64 hours, then the oxygen, ethylene, and HCl flows were started and oxychlorination was carried out for about 104 hours. The oxygen, ethylene, and HCl feeds were then stopped and the catalyst was fluidized with a nitrogen / oxygen blend at 200° C. for another 64 hours. The oxygen, ethylene, and HCl feeds were started again after about 64 hours and oxychlorination was continued for about another 104 hours, which represents run 10. The same pattern was followed for runs 11 and 12, except that in run 12, the catalyst was heated to 230° C. under fluidization for 64 hours. Comparing run 12 with run 9, it can be seen that heating the catalyst at 200°C for 64 hours did not activate the catalyst to the same extent as heating for longer periods at 200°C (see runs 10 and 11) or at higher temperatures (see run 12). It should be noted, however, that runs 10 and 11 show a trend for activation at 200°C ultimately improving catalyst performance as activation time is extended. [Table 3]

[0062] Dataset IV-Runs 13-16 A fourth data set, summarized in Table IV below, shows that the catalyst must be activated in the reactor under fluidized conditions. The catalysts used in Runs 14 and 16 were activated according to the present invention, while an attempt was made to activate the catalysts used in Runs 13 and 15 in an oven at 230° C. for 64 hours. The catalyst used in Run 13 was cooled to 110° C. for 24 hours before being loaded into the reactor, while the catalyst used in Run 15 was transferred directly from the oven to the reactor. As the data shows, neither of the oven-heated catalysts (Runs 13 and 15) were activated as well as the catalysts activated according to the present invention (Runs 14 and 16). [Table 4]

[0063] Data set V-Run 17-20 A fifth data set, summarized in Table V below, shows that the findings related to the present invention extend to other catalytic systems. For example, catalysts using potassium and rare earth metals, known catalytic systems for oxychlorination, would benefit from the practice of the present invention. The catalysts used in this experiment (Runs 17 and 18) contained 1.5 wt.% lanthanum, 0.5 wt.% cerium, and 0.5 wt.% praseodymium (represented as 2.5 wt.% rare earths in Table V). As the data suggests, activation of the catalyst according to the present invention (i.e., Run 18) resulted in higher HCl conversion at lower temperatures with the same EDC selectivity compared to the same system but unactivated (i.e., Run 17). Similar results are shown for catalysts containing copper and magnesium (Runs 19 and 20). [Table 5]

[0064] Various modifications and alterations that do not depart from the scope and spirit of this invention will become apparent to those skilled in the art. This invention is not duly limited to the illustrative embodiments set forth herein.

Claims

1. A method for producing 1,2-dichloroethane, comprising the steps of: (i) providing a fluidizable catalyst; (ii) charging the fluidizable catalyst into a fluidized bed reactor; (iii) fluidizing the catalyst in the fluidized bed reactor; (iv) heating the catalyst in the fluidized bed reactor to a temperature greater than 150° C. for more than 6 hours while fluidizing the catalyst in the fluidized bed reactor, wherein the fluidizing and heating steps are performed in the absence of ethylene conversion; and (v) after said heating step, converting ethylene to 1,2-dichloroethane in the presence of said catalyst. A method comprising:

2. 10. The method of claim 1, wherein the heating step is performed for more than 12 hours.

3. 10. The method of claim 1, wherein the heating step occurs for more than 24 hours.

4. 10. The method of claim 1, wherein the heating step occurs for more than 36 hours.

5. 10. The method of claim 1, wherein the heating step heats the catalyst to a temperature greater than 170°C.

6. 10. The method of claim 1, wherein the heating step heats the catalyst to a temperature greater than 190°C.

7. 10. The method of claim 1, wherein the heating step heats the catalyst to a temperature greater than 210°C.

8. 10. The method of claim 1 further comprising the step of supplying oxygen to the fluidized bed reactor.

9. 2. The process of claim 1, wherein the step of converting ethylene to 1,2-dichloroethane comprises feeding ethylene to the fluidized bed reactor.

10. 2. The process of claim 1, wherein the step of converting ethylene to 1,2-dichloroethane comprises feeding hydrochloric acid to the fluidized bed reactor.

11. 10. The method of claim 1, wherein the heating and fluidizing steps are carried out in the substantial absence of hydrochloric acid.

12. The method of claim 1 , wherein the heating step is carried out in the presence of oxygen, and / or an oxygen-containing gas, and / or an inert gas.

13. 2. The method of claim 1, wherein the heating step provides a heated catalyst, the temperature of the catalyst being maintained above 150° C. at least until the step of providing ethylene.

14. The method of claim 1 , wherein the fluidizable catalyst comprises a support impregnated with catalytic metal species.

15. The method of claim 14 , wherein the catalytic metal species comprises copper.

16. The method of claim 14, wherein the catalytic metal species include copper, magnesium and zirconium.

17. 2. The process of claim 1 , wherein the ethylene contacts the catalyst in a reaction zone of the fluidized bed reactor.

18. 10. The process of claim 1 further comprising recovering 1,2-dichloroethane from the fluidized bed reactor effluent.

19. The method of claim 14, wherein the support is high surface area alumina.

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