| WO2013061336A2 | 2013-05-02 |
| US5098668A | 1992-03-24 | |||
| US20120237410A1 | 2012-09-20 | |||
| US20070142690A1 | 2007-06-21 |
| What is claimed is: 1. An alkylation process comprising: pre-mixing a paraffin stream with an ionic liquid catalyst stream from a settler to form a pre-mixed paraffin and ionic liquid catalyst stream; mixing the premixed paraffin and ionic liquid catalyst stream in a low efficiency pump to form a paraffin and ionic liquid catalyst mixture; introducing an olefin feed stream into a riser reactor; introducing the paraffin and ionic liquid catalyst mixture into the riser reactor to form a reaction mixture comprising alkylate and the ionic liquid catalyst; separating the reaction mixture in a settler into an ionic liquid catalyst stream and a hydrocarbon stream. 2. The process of claim 1 wherein the hydrocarbon stream includes unreacted paraffin, and further comprising: separating the hydrocarbon stream into an alkylate product stream and an paraffin recycle stream; wherein the paraffin recycle stream comprises at least a portion of the paraffin stream. 3. The process of any of claims 1-2 further comprising at least one of: cooling the paraffin stream; and cooling the olefin feed stream. 4. The process of any of claims 1-2 wherein introducing the olefin feed stream into the riser reactor comprises introducing the olefin feed stream into the riser reactor at more than one location. 5. The process of any of claims 1-2 wherein the paraffin stream comprises an isoparaffin having from 3 to 10 carbon atoms, or wherein the olefin feed stream comprises an olefin having from 2 to 10 carbon atoms, or both. 6. The process of any of claims 1-2 further comprising: regenerating a portion of the ionic liquid catalyst before pre-mixing the paraffin stream with the ionic liquid catalyst stream. 7. The process of any of claims 1-2 wherein the settler further comprises a coalescing material. 8 The process of any of claims 1-2 further comprising introducing a slipstream of at least one of the paraffin and the ionic liquid catalyst into the bottom of the settler. 9. The process of any of claims 1-2 further comprising mixing the olefin feed stream with the paraffin and ionic liquid catalyst mixture before introducing the olefin feed stream into the riser reactor. 10. An alkylation apparatus comprising: a riser reactor having at least one inlet and an outlet; a settler having an inlet, a hydrocarbon outlet, and an ionic liquid outlet, the settler inlet being in fluid communication with the riser reactor outlet; a premixer having at least one inlet, and an outlet, the at least one inlet of the pre-mixer being in fluid communication with the ionic liquid outlet of the settler; a low efficiency pump having an inlet and an outlet, the pump inlet being in fluid communication with the premixer outlet, the pump outlet being in fluid communication with the at least one inlet of the riser reactor. |
IONIC LIQUID ALKYLATION
STATEMENT OF PRIORITY
This application claims priority to U.S. Provisional Application No. 62/196171 which was filed July 23, 2015, the contents of which are hereby incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
There are a variety of hydrocarbon conversion processes, and these processes utilize different catalysts.
Alkylation is typically used to combine light olefins, for example mixtures of alkenes such as propylene and butylene, with isobutane to produce a relatively high-octane branched-chain paraffinic hydrocarbon fuel, including isoheptane and isooctane. Similarly, an alkylation reaction can be performed using an aromatic compound such as benzene in place of the isobutane. When using benzene, the product resulting from the alkylation reaction is an alkylbenzene (e.g. toluene, xylenes, ethylbenzene, etc.).
The alkylation of paraffins with olefins for the production of alkylate for gasoline can use a variety of catalysts. The choice of catalyst depends on the end product a producer desires. Typical alkylation catalysts include concentrated sulfuric acid or hydrofluoric acid. However, sulfuric acid and hydrofluoric acid are hazardous and corrosive, and their use in industrial processes requires a variety of environmental controls.
Ionic liquids provide advantages over other catalysts, including being less corrosive than catalysts like HF, and being non-volatile.
However, the current design for alkylation unit employing ionic liquid catalysts utilizes multiple mixer-reactors which increases capital expenses. The costs associated with the equipment needed to operate such a unit reduces the likelihood of commercial adoption of the process.
Therefore, there is a need a lower cost process for ionic liquid catalyzed alkylation. SUMMARY OF THE INVENTION
One aspect of the present invention is an alkylation process. In one embodiment, the alkylation process includes pre-mixing a paraffin stream with an ionic liquid catalyst stream from a settler to form a pre-mixed paraffin and ionic liquid catalyst stream. The premixed paraffin and ionic liquid catalyst stream is mixed in a variable speed, low- efficiency pump to form a paraffin and ionic liquid catalyst mixture. An olefin feed stream is introduced into a riser reactor. The paraffin and ionic liquid catalyst mixture is introduced into the riser reactor to form a reaction mixture comprising alkylate and the ionic liquid catalyst. The reaction mixture is separated in a settler into an ionic liquid catalyst stream and a hydrocarbon stream.
Another aspect of the invention is an alkylation apparatus. In one embodiment, the alkylation apparatus includes a riser reactor having at least one inlet and an outlet; a settler having an inlet, a hydrocarbon outlet, and an ionic liquid outlet, the settler inlet being in fluid communication with the riser reactor outlet; a premixer having at least one inlet, and an outlet, the at least one inlet of the pre-mixer being in fluid communication with the ionic liquid outlet of the settler; and a variable speed, low efficiency pump having an inlet and an outlet, the pump inlet being in fluid communication with the premixer outlet, the pump outlet being in fluid communication with the at least one inlet of the riser reactor.
BRIEF DESCRIPTION OF THE DRAWING Fig. 1 illustrates one embodiment of an HF alkylation process.
Fig. 2 illustrates one embodiment of analkylation process according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The process closely follows current HF alkylation gravity feed reactor systems with some modifications, allowing the simple conversion of existing HF alkylation units to ionic liquid catalyst.
Fig. 1 illustrates a typical HF alkylation unit 100. A riser reactor 105 receives a feed 110 and an HF alkylation catalyst 115. The riser reactor 105 can provide the reaction effluent 120 to a settler 125. Several phases can form in the settler 125 including a hydrocarbon phase that can be extracted as a hydrocarbon effluent 130 and an acid phase 135. The riser reactor 105 and settler 125 can be operated at any suitable condition. Particularly, the riser reactor 105 can be operated at a pressure of 440- 800 kPa and the settler 125 can be operated at a pressure of no more than 1,500 kPa, typically no more than 1,100 kPa.
Generally, the hydrocarbon effluent 130 is provided to one or more columns (not shown) for separating out an alkylate product as well as recycling a paraffin, such as isobutane.
The acid phase 135 contains HF alkylation catalyst as well as some unreacted paraffin. The acid phase 135 can be at least partially spent and a portion can be recycled to the riser reactor 105as HF alkylation catalyst 115 while another portion 140 is sent for regeneration in FIF catalyst regeneration zone 145.
Exemplary settlers, alkylation reactors, and fractionation zones, are disclosed in, e.g., U.S. Pat. No. 5,098,668.
The HF catalyst regeneration zone 145 separates the HF catalyst and unreacted paraffin 150 from the acid soluble oils 155 formed during the alkylation process. The HF catalyst and unreacted paraffin 150 is sent to the settler 125, and the acid soluble oils 155 are removed. One example of an HF catalyst regeneration zone 145 is described in U.S. Pat. No. 8,227,366.
This system can be easily modified to accommodate an ionic liquid catalyst. Fig. 2 shows an illustration of the process 200. The riser reactor and settler from the existing HF alkylation unit are maintained.
The paraffin stream 205 can include recycled paraffin from a downstream fractionation zone (not shown) and/or paraffin from one or more other refinery or chemical manufacturing units.
In some embodiments, the paraffin stream 205 is cooled to limit reactor outlet temperature. The paraffin stream 205 is pre-mixed with the ionic liquid catalyst stream 210 collected from the settler sump in a pre-mixer 215. The pre-mixer 215 could be a fixed or static mechanical mixer. For example, it could be a perforated pipe, a helical inline mixer, or a static mixer. The premixed ionic liquid and paraffin stream 220 is processed through a low efficiency pump 225 which serves as a final mixer. A low efficiency pump utilizes a significant portion of the energy to produce droplets of one, some, or all of the fluids being moved through the pump, and to mix the fluids within the pump. In some embodiments, the low efficiency pump creates an emulsion of the ionic liquid in the paraffin. The term mixture is intended to cover emulsions. The low efficiency pump 225 can be a variable RPM mixer or a variable speed mixer to control the ionic liquid catalyst droplet size and size distribution. Suitable low efficiency pumps include, but are not limited to high shear pumps, rotor-stator pumps, and cavitation reactor pumps.
The paraffin and ionic liquid mixture stream 230 is sent to the reactor riser
235, along with an olefin feed stream 240. The olefin feed stream 240 could contain a single olefin, or a mixture of olefins. The olefin feed stream 240 could also contain any make-up paraffin needed. In some embodiments, the olefin feed stream 240 could be introduced at multiple elevations to help control residence time and to minimize the likelihood of localized spots of high olefin concentration. In some embodiments, the mixed olefin feed stream 240 is cooled to control the reactor outlet temperature.
Typical alkylation reaction conditions include a temperature in the range of 20°C to the decomposition temperature of the ionic liquid, or 20°C to 100°C, or 20°C to 80°C, or 0°C to 80°C, or 20°C to 80°C. It is preferred to have an ionic liquid that maintains its liquid state through the operating temperature range.
The pressure is typically in the range of atmospheric (0.1 MPa (g)) to 8.0 MPa (g), or 0.3 MPa (g) to 2.5 MPa (g). The pressure is preferably sufficient to keep the reactants in the liquid phase.
The residence time of the reactants in the reaction zone is in the range of a few seconds to 20 minutes, or 30 sec to 10 min, or 1 min to 10 min, or 1 min to 8 min, or 1 min to 6 min, or 2 min to 6 min.
Generally, the alkylation reaction is carried out with substantial molar excess of paraffin: olefin, typically in excess of 0.5: 1, usually 1 : 1 to 70: 1, or 1 : 1 to 20: 1. Usually, the system has a catalyst volume in the reactor of from 1 vol % to 50 vol %, or 1 vol % to 40 vol %, or 1 vol % to 30 vol %, or 1 vol % to 20 vol %, or 1 vol % to 10 vol %, or 5 vol % to 10 vol %. The reactor riser effluent stream 245, which contains the alkylation products, the ionic liquid catalyst, and any unreacted paraffin, is sent to the vertical settler vessel 250 where the riser reactor effluent stream 245 separates into and ionic liquid catalyst phase and a hydrocarbon phase. Small amounts of the hydrocarbon may remain in the ionic liquid phase, and small amounts of ionic liquid may remain in the hydrocarbon phase (e.g., less than 5%). The heavier ionic liquid phase accumulates in the sump.
In some embodiments, mechanical and/or non-mechanical separators 255, for example, a coalescing material, or contacting trays, are installed to prevent smaller drops of ionic liquid from being conveyed overhead with the hydrocarbon effluent 260. The hydrocarbon effluent 260 could be pressurized or pumped to the fractionation section (not shown). In some embodiments, a slipstream of paraffin265 may be introduced into the bottom of the settler 250 via a sparger to prevent the ionic liquid catalyst from settling and solidifying. In some embodiments, a slipstream 270 may also be introduced into the bottom of the settler 250.
Multiple pre-mixers, low efficiency pumps, and/or risers could be provided to assist in residence time control and/or to increase throughput.
The paraffin used in the alkylation process preferably comprises a paraffin having from 2 to 10 carbon atoms, or 2 to 8 carbon atoms, or 4 to 8 carbon atoms, or 4 to 5 carbon atoms. In some embodiments, the paraffin is an isoparaffin having 3 to 10 carbons atoms, or 4 to 8 carbon atoms, or 4 to 5 carbon atoms. The olefin used in the alkylation process preferably has from 2 to 10 carbon atoms, or 2 to 8 carbon atoms, 3 to 8 carbon atoms, or 3 to 5 carbon atoms. One application of the process is to upgrade low value C 3 - C 5 hydrocarbons to higher value alkylates.
Usually, the alkylation reaction can include the reaction of an isoparaffin, such as isobutane, with an olefin or other alkylating agent such as propylene, isobutylene, butene- 1, butenes-2, and amylenes. Generally, the reaction of an isoparaffin with a C 3 or a C 4 olefin, such as isobutylene, butene-1, and/or butenes-2, is an example of a preferred reaction involving these specified materials and mixture.
One specific embodiment is the alkylation of butanes with butylenes to generate C 8 compounds. Preferred products include trimethylpentane (TMP), and while other C 8 isomers are produced, one competing isomer is dimethylhexane (DMH). The quality of the product stream can be measured in the ratio of TMP to DMH, with a high ratio desired. The ionic liquid can be any acidic ionic liquid. There can be one or more ionic liquids. The ionic liquid comprises an organic cation and an anion. Suitable cations include, but are not limited to, nitrogen-containing cations and phosphorus-containing cations. Suitable organic cations include, but are not limited
where R^R 21 are independently selected from C1-C20 hydrocarbons, C1-C20 hydrocarbon derivatives, halogens, and H. Suitable hydrocarbons and hydrocarbon derivatives include saturated and unsaturated hydrocarbons, halogen substituted and partially substituted hydrocarbons and mixtures thereof. Ci-C 8 hydrocarbons are particularly suitable.
The anion can be derived from halides, typically halometallates, and combinations thereof. The anion is typically derived from metal and nonmetal halides, such as metal and nonmetal chlorides, bromides, iodides, fluorides, or combinations thereof. Combinations of halides include, but are not limited to, mixtures of two or more metal or nonmetal halides (e.g., AICI4 " and BF 4 " ), and mixtures of two or more halides with a single metal or nonmetal (e.g., AlCl 3 Br " ). In some embodiments, the metal is aluminum, with the mole fraction of aluminum ranging from 0 < Al < 0.25 in the anion. Suitable anions include, but are not limited to, A1C1 4 " , A1 2 C1 7 " , Al 3 Cli 0 " , AlCl 3 Br " , Al 2 Cl 6 Br " , Al 3 Cl 9 Br " , AlBr 4 " , Al 2 Br 7 " , Al 3 Br 10 " , GaCl 4 " , Ga 2 Cl 7 " , Ga 3 Cli 0 " , GaCl 3 Br " , Ga 2 Cl 6 B , Ga 3 Cl 9 Br CuCl 2 " , Cu 2 Cl 3 " , Cu 3 Cl 4 " , ZnCl 3 " , FeCl 3 " , FeCl 4 " , Fe 3 Cl 7 " , PF 6 " , and BF 4 " .
A variety of methods for regenerating ionic liquids have been developed. For example, US 7,651,970; US 7,825,055; US 7,956,002; US 7,732,363, each of which is incorporated herein by reference, describe contacting ionic liquid containing the conjunct polymer with a reducing metal (e.g., Al), an inert hydrocarbon (e.g., hexane), and hydrogen and heating to 100°C to transfer the conjunct polymer to the hydrocarbon phase, allowing for the conjunct polymer to be removed from the ionic liquid phase. Another method involves contacting ionic liquid containing conjunct polymer with a reducing metal (e.g., Al) in the presence of an inert hydrocarbon (e.g. hexane) and heating to 100°C to transfer the conjunct polymer to the hydrocarbon phase, allowing for the conjunct polymer to be removed from the ionic liquid phase. See e.g., US 7,674,739 B2; which is incorporated herein by reference. Still another method of regenerating the ionic liquid involves contacting the ionic liquid containing the conjunct polymer with a reducing metal (e.g., Al), HCl, and an inert hydrocarbon (e.g. hexane), and heating to 100°C to transfer the conjunct polymer to the hydrocarbon phase. See e.g., US 7,727,925, which is incorporated herein by reference. The ionic liquid can be regenerated by adding a homogeneous metal hydrogenation catalyst (e.g., (PPh 3 ) 3 RhCl) to ionic liquid containing conjunct polymer and an inert hydrocarbon (e.g. hexane), and introducing hydrogen. The conjunct polymer is reduced and transferred to the hydrocarbon layer. See e.g., US 7,678,727, which is incorporated herein by reference. Another method for regenerating the ionic liquid involves adding HCl, isobutane, and an inert hydrocarbon to the ionic liquid containing the conjunct polymer and heating to 100°C. The conjunct polymer reacts to form an uncharged complex, which transfers to the hydrocarbon phase. See e.g., US 7,674,740, which is incorporated herein by reference. The ionic liquid could also be regenerated by adding a supported metal hydrogenation catalyst (e.g. Pd/C) to the ionic liquid containing the conjunct polymer and an inert hydrocarbon (e.g. hexane). Hydrogen is introduced and the conjunct polymer is reduced and transferred to the hydrocarbon layer. See e.g., US 7,691,771, which is incorporated herein by reference. Still another method involves adding a suitable substrate (e.g. pyridine) to the ionic liquid containing the conjunct polymer. After a period of time, an inert hydrocarbon is added to wash away the liberated conjunct polymer. The ionic liquid precursor [butylpyridinium] [CI] is added to the ionic liquid (e.g. [butylpyridinium] [AI 2 CI 7 ]) containing the conjunct polymer followed by an inert hydrocarbon. After mixing, the hydrocarbon layer is separated, resulting in a regenerated ionic liquid. See, e.g., US 7,737,067, which is incorporated herein by reference. Another method involves adding ionic liquid containing conjunct polymer to a suitable substrate (e.g. pyridine) and an electrochemical cell containing two aluminum electrodes and an inert hydrocarbon. A voltage is applied, and the current measured to determine the extent of reduction. After a given time, the inert hydrocarbon is separated, resulting in a regenerated ionic liquid. See, e.g., US 8,524,623, which is incorporated herein by reference. Ionic liquids can also be regenerated by contacting with silane compounds (U.S. Application Serial No. 14/269,943), borane compounds (US. Application Serial No. 14/269,978), Bransted acids, (US Application Serial No. 14/229,329), or Ci to Cio Paraffins (US Application Serial No. 14/229,403), each of which is incorporated herein by reference.
SPECIFIC EMBODIMENTS
While the following is described in conjunction with specific embodiments, it will be understood that this description is intended to illustrate and not limit the scope of the preceding description and the appended claims.
A first embodiment of the invention is a process comprising pre- mixing a paraffin stream with an ionic liquid catalyst stream from a settler to form a pre- mixed paraffin and ionic liquid catalyst stream; mixing the premixed paraffin and ionic liquid catalyst stream in a low efficiency pump to form a paraffin and ionic liquid catalyst mixture; introducing an olefin feed stream into a riser reactor; introducing the paraffin and ionic liquid catalyst mixture into the riser reactor to form a reaction mixture comprising alkylate and the ionic liquid catalyst; separating the reaction mixture in a settler into an ionic liquid catalyst stream and a hydrocarbon stream. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the hydrocarbon stream includes unreacted paraffin, and further comprising separating the hydrocarbon stream into an alkylate product stream and an paraffin recycle stream; wherein the paraffin recycle stream comprises at least a portion of the paraffin stream. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising cooling the paraffin stream. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising cooling the olefin feed stream. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein introducing the olefin feed stream into the riser reactor comprises introducing the olefin feed stream into the riser reactor at more than one location. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the paraffin stream comprises an isoparaffin having from 3 to 10 carbon atoms. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the olefin feed stream comprises an olefin having from 2 to 10 carbon atoms. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising regenerating a portion of the ionic liquid catalyst before pre-mixing the paraffin stream with the ionic liquid catalyst stream. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the settler further comprises a coalescing material. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising introducing a slipstream of at least one of the paraffin and the ionic liquid catalyst into the bottom of the settler. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising mixing the olefin feed stream with the paraffin and ionic liquid catalyst mixture before introducing the olefin feed stream into the riser reactor.
A second embodiment of the invention is a process comprising pre- mixing an isoparaffin stream with an ionic liquid catalyst stream from a settler to form a pre- mixed isoparaffin and ionic liquid catalyst stream, the isoparaffin stream comprising isoparaffins having from 2 to 10 carbon atoms; mixing the premixed isoparaffin and ionic liquid catalyst stream in a low efficiency pump to form an isoparaffin and ionic liquid catalyst mixture; introducing an olefin feed stream to a riser reactor, the olefin feed stream comprising olefins having from 2 to 10 carbon atoms; introducing the isoparaffin and ionic liquid catalyst mixture into the riser reactor to form a reaction mixture comprising alkylate, unreacted isoparaffin, and the ionic liquid catalyst; separating the reaction mixture in the settler into an ionic liquid catalyst stream and a hydrocarbon stream comprising the alkylate and the unreacted isoparaffin; and separating the hydrocarbon stream into an alkylate product stream and an isoparaffin recycle stream; wherein the isoparaffin recycle stream comprises at least a portion of the isoparaffin stream. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising cooling at least one of the isoparaffin stream, and the olefin feed stream. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein introducing the olefin feed stream to the riser reactor comprises introducing the olefin feed stream to the riser reactor at more than one location. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising regenerating a portion of the ionic liquid catalyst before pre-mixing the isoparaffin stream with the ionic liquid catalyst stream. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the settler further comprises a coalescing material. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising introducing a slipstream of at least one of isoparaffin and the ionic liquid catalyst into the bottom of the settler. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising mixing the olefin feed stream with the isoparaffin and ionic liquid catalyst mixture before introducing the olefin feed stream to the riser reactor.
A third embodiment of the invention is an apparatus comprising a riser reactor having at least one inlet and an outlet; a settler having an inlet, a hydrocarbon outlet, and an ionic liquid outlet, the settler inlet being in fluid communication with the riser reactor outlet; a premixer having at least one inlet, and an outlet, the at least one inlet of the pre- mixer being in fluid communication with the ionic liquid outlet of the settler; a low efficiency pump having an inlet and an outlet, the pump inlet being in fluid communication with the premixer outlet, the pump outlet being in fluid communication with the at least one inlet of the riser reactor. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph further comprising a fractionation zone having an inlet, a product outlet, and a paraffin outlet, the fractionation zone inlet being in fluid communication with the hydrocarbon outlet of the settler, the fractionation zone paraffin outlet being in fluid communication with the at least one inlet of the premixer.
Without further elaboration, it is believed that using the preceding description that one skilled in the art can utilize the present invention to its fullest extent and easily ascertain the essential characteristics of this invention, without departing from the spirit and scope thereof, to make various changes and modifications of the invention and to adapt it to various usages and conditions. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limiting the remainder of the disclosure in any way whatsoever, and that it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims. In the foregoing, all temperatures are set forth in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.