Reaction assembly for monochloroacetic acid

Abstract

The present application discloses a reaction assembly for monochloroacetic acid, which comprises a reactor, a catalytic bed and a distribution member, the reactor has a low end portion and a high end portion higher than the low end portion, the reactor forms a chamber between the high end portion and the low end portion, wherein the low end portion of the reactor has a gas inlet and a feed inlet both communicating with the chamber, and the high end portion of the reactor has a discharge outlet communicating with the chamber; a catalytic bed for carrying a catalyst for catalyzing a hydrogenation dechlorination reaction of dichloroacetic acid, wherein the catalytic bed is filled in the chamber and held at the high end portion and located on a flow path of mixed hydrogen and reaction liquid flowing to the discharge outlet; and the distribution member is configured to divide the reaction liquid introduced from the gas inlet and the feed inlet radially and axially to contact the catalyst on the catalytic bed and then guide the reaction liquid from bottom to top to the discharge outlet of the high end portion.

Description

Technical Field

[0001] This application relates to the field of organic compound preparation technology, and more particularly to a reaction assembly for monochloroacetic acid. Background Technology

[0002] Monochloroacetic acid (MCA) is an important organic chemical intermediate widely used in pesticides, pharmaceuticals, dyes, carboxymethyl cellulose (CMC), surfactants, and other fields. Currently, there are three main methods for producing chloroacetic acid both domestically and internationally: the sulfur-catalyzed batch process, the acetic anhydride-catalyzed batch process, and the acetic anhydride hydrogenation continuous process.

[0003] The continuous hydrogenation process of acetic anhydride has become the mainstream chloroacetic acid production process at home and abroad due to its advantages such as high product quality, low raw material consumption, no mother liquor generation, and high degree of automation.

[0004] The continuous process for producing chloroacetic acid from acetic anhydride mainly includes a chlorination and hydrolysis section, a hydrogenation reduction section, a distillation section, and a tail gas absorption section. During the chlorination reaction, deep chlorination side reactions inevitably occur, producing dichloroacetic acid and trichloroacetic acid. Chloroacetyl chloride reacts with chlorine gas to produce dichloroacetyl chloride, as shown in the following reaction equations: ClCH2COCl + Cl2 → Cl2CHCOCl + HCl; Cl2CHCOCl + CH3COOH → Cl2CHCOOH + CH3COCl Dichloroacetic acid (DCA) is one of the main byproducts produced during the chlorination reaction of chloroacetic acid. According to the "Industrial Chloroacetic Acid" standard (HG / T 3271-2000) and the latest industry standards, superior grade chloroacetic acid requires a dichloroacetic acid content of no more than 0.4% wt. As an important intermediate in organic synthesis, the purity of monochloroacetic acid directly affects the quality and performance of downstream products.

[0005] To reduce the content of dichloroacetic acid and trichloroacetic acid in the product and improve the purity and yield of monochloroacetic acid, the existing process uses a trickle-bed liquid-phase hydrogenation reactor to carry out the hydrogenation and dechlorination reaction under the action of a catalyst, as shown in the following reaction formula: Cl2CHCOOH + H2 → ClCH2COOH + HCl; while trichloroacetic acid undergoes hydrogenation and dechlorination to produce dichloroacetic acid, which is further dechlorinated to produce monochloroacetic acid, as shown in the following reaction formulas: Cl3CCOOH + H2 → Cl2CHCOOH + HCl, Cl2CHCOOH + H2 → ClCH2COOH + HCl.

[0006] Furthermore, the hydrodechlorination reaction is exothermic, and the reaction temperature is typically controlled within the range of 130–180°C. Excessively high temperatures accelerate the over-reduction side reaction, increasing the amount of acetic acid produced; conversely, excessively low temperatures result in a slow reaction rate and decreased conversion. In traditional trickle-bed reactors, limited mass and heat transfer within the catalyst bed easily leads to localized hot spots, resulting in decreased selectivity and catalyst sintering and deactivation.

[0007] More importantly, hydrogenation involves a three-phase system: gaseous hydrogen, liquid reactants, and a solid catalyst. Hydrogen has limited solubility in the liquid phase, and gas-liquid mass transfer is often the rate-determining step. In trickle bed reactors, the low liquid flow rate, incomplete catalyst wetting, and uneven hydrogen distribution easily lead to channeling and short-circuiting, resulting in some catalyst not being fully utilized and reduced reaction efficiency. Summary of the Invention

[0008] To address the aforementioned technical problems, this application provides a reaction assembly for monochloroacetic acid, the reaction assembly comprising: A reactor having a lower end and a higher end above the lower end, the reactor forming a chamber between the higher end and the lower end, wherein the lower end of the reactor has an air inlet and a feed inlet communicating with the chamber, and wherein the higher end of the reactor has a discharge outlet communicating with the chamber. A catalyst bed for supporting the catalyst for the hydrodechlorination reaction of dichloroacetic acid, wherein the catalyst bed is filled in the chamber and held at the upper end, and located in the flow path of the mixed hydrogen and reaction liquid to the outlet; A distribution member; wherein the distribution member is configured to uniformly contact the catalyst on the catalyst bed by splitting the hydrogen introduced from the gas inlet and the reaction liquid introduced from the feed inlet in the radial and axial directions, and then guide them from bottom to top to the discharge port of the high-end section.

[0009] According to one embodiment of this application, the distribution member includes a flow equalization layer configured to uniformly distribute hydrogen gas introduced from the gas inlet and reaction liquid introduced from the feed inlet via the flow equalization layer in a radial and axial direction.

[0010] According to one embodiment of this application, the distribution component includes a liquid distribution assembly, the liquid distribution assembly includes an injector, wherein the injector has a release port communicating with the air inlet and the feed inlet, the release port being held in the chamber and located below the catalyst bed, wherein the release port is disposed toward the catalyst bed.

[0011] According to one embodiment of this application, the distribution component includes a liquid distribution assembly, the liquid distribution assembly includes an injector, wherein the injector has a release port communicating with the air inlet and the feed inlet, the release port being held in the chamber and located below the catalyst bed, wherein the release port is disposed toward the flow equalization layer.

[0012] According to one embodiment of this application, the liquid distribution assembly includes a circulation pump, wherein the circulation pump and the feed inlet are connected.

[0013] According to one embodiment of this application, the flow equalization layer is configured to disperse the mixed hydrogen gas and reaction liquid into multiple streams that are sprayed upwards toward the catalyst bed, and the hydrogen gas in the streams contacts the catalyst bed in the form of bubble aeration.

[0014] According to one embodiment of this application, the flow equalization layer is implemented as a plurality of ceramic spheres with channels.

[0015] According to one embodiment of this application, the reaction assembly for monochloroacetic acid includes a reaction liquid separation tank, wherein the reaction liquid separation tank has a communication port connected to the reactor and a gas outlet, wherein the communication port is connected to the discharge port and the gas outlet is used to discharge by-product gas.

[0016] According to one embodiment of this application, the reaction assembly for monochloroacetic acid includes a demister, wherein the demister is disposed at the gas outlet of the reaction liquid separation tank.

[0017] According to one embodiment of this application, the reaction assembly for monochloroacetic acid further includes a non-condensable gas condenser, wherein the non-condensable gas condenser is configured to condense the gaseous reaction liquid in the by-product gas flowing out from the gas outlet to prevent it from being carried out by the non-condensable gas.

[0018] According to one embodiment of this application, the reaction assembly for monochloroacetic acid includes a noncondensable gas separator and a gas assembly, wherein the noncondensable gas separator is connected to the gas outlet of the reaction liquid separator; wherein the gas assembly is configured to fill the noncondensable gas separator with inert gas or nitrogen from bottom to top, and the top of the noncondensable gas separator has a gas outlet.

[0019] According to one embodiment of this application, the bottom of the non-condensable gas separator is connected to the reaction liquid separator.

[0020] According to one embodiment of this application, the reaction assembly for monochloroacetic acid includes a flow regulating component, wherein the flow regulating component includes a flow regulating channel communicating with the reaction liquid separation tank and a flow regulating valve disposed in the flow regulating channel.

[0021] According to one embodiment of this application, the reaction assembly for monochloroacetic acid includes a temperature control component, wherein the temperature control component includes a reaction liquid channel, a reaction liquid regulating valve disposed in the reaction liquid channel, and a temperature control device, wherein the reaction liquid channel is connected to the reaction liquid separation tank and the feed inlet, wherein the reaction liquid located in the reaction liquid channel is configured to exchange heat with the temperature control device, and then mixed with the reaction liquid before entering the reactor from the feed inlet, and then introduced into the reactor together.

[0022] According to one embodiment of this application, the catalyst is implemented as a palladium catalyst placed on activated carbon, wherein the palladium content is 0.1% to 5%.

[0023] Technical effects of this application: 1. The operation mode of liquid material and hydrogen flowing upward through the catalyst bed is adopted, so that the liquid phase fills the catalyst bed as a continuous phase, and the hydrogen rises in the form of discrete bubbles after being uniformly dispersed at the bottom of the catalyst bed, so as to achieve uniform contact between the gas and liquid phases in the radial and axial directions. 2. The reactor described in this application is arranged with a bottom-inlet and top-outlet flow direction, which allows the hydrogen-containing activation medium to rise uniformly from the bottom of the bed, fully wets the catalyst bed, and distributes hydrogen evenly, effectively avoiding liquid phase channeling and short-circuiting phenomena.

[0024] 3. This application can remove the heat of reaction, so that the catalyst bed is always kept within the optimal reaction temperature range, thereby reducing the risk of over-hydrogenation. Attached Figure Description

[0025] Figure 1 This is a reaction process flow diagram of a preferred embodiment of this application.

[0026] Figure 2 This is a reaction process flow diagram of another preferred embodiment of this application. Detailed Implementation

[0027] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0028] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0029] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0030] refer to Figure 1 A preferred embodiment of the present invention, a reaction assembly for monochloroacetic acid, will be described in detail below, wherein the reaction assembly for monochloroacetic acid includes a reactor 100, a catalyst bed 200, and a distribution member 300.

[0031] The reactor 100 has a high-end portion 110 and a low-end portion 120, wherein the reactor 100 forms a chamber 1001 between the high-end portion 110 and the low-end portion 120. The reactor 100 also has a discharge port 1002 disposed in the high-end portion 110 and communicating with the chamber 1001, and an inlet 1003 and a feed port 1004 disposed in the low-end portion 120 and communicating with the chamber 1001, for introducing hydrogen gas and a reaction liquid (such as...) respectively. Figure 2 As shown, chloroacetic acid feed.

[0032] The catalyst bed 200 is filled in the chamber 1001 and held in the upper part 110, located in the flow path of the mixed hydrogen and reaction liquid towards the outlet 1002. Notably, a catalyst for the hydrodechlorination reaction of dichloroacetic acid is arranged on the catalyst bed 200. In a preferred embodiment, the catalyst is implemented as a palladium catalyst (Pd / C) on activated carbon.

[0033] It is worth mentioning that activated carbon, as a carrier, possesses a high specific surface area, a well-developed pore structure, and excellent adsorption properties, which can effectively disperse the palladium active component and improve catalytic efficiency. Preferably, the palladium content is 0.1% to 5% (mass fraction); more preferably, the palladium metal content is 0.1% to 1.0%. Also preferably, the catalyst morphology can be powder, granules, or shaped columnar / spherical forms; more preferably, the diameter of the spherical catalyst is 0.2 to 15 mm.

[0034] In one embodiment, the distribution member 300 is configured to mix hydrogen introduced from the inlet 1003 with the reaction liquid introduced from the feed inlet 1004, then flow radially and axially through the catalyst bed 200, and finally be guided upwards to the outlet 1002 of the high-end section 110. Those skilled in the art will understand that this allows the hydrogen in the reaction liquid to fully and uniformly contact the catalyst in the catalyst bed 200, thereby achieving sufficient contact in the gas (hydrogen)-liquid (reaction liquid)-solid (catalyst) three-phase system. This effectively solves the problems of low liquid flow rate, incomplete catalyst wetting, uneven hydrogen distribution, and the tendency for channeling and short-circuiting that often occur in trickle-bed reactors, preventing the underutilization of some catalyst and addressing the issue of reduced reaction efficiency.

[0035] In one embodiment, the distribution member 300 includes a flow equalization layer 310, wherein the flow equalization layer 310 comprises a plurality of porous microspheres to uniformly distribute hydrogen gas introduced from the gas inlet 1003 and the reaction liquid introduced from the feed inlet 1004 through the flow equalization layer 310 in a radial and axial split. It is worth noting that the flow equalization layer 310 can also effectively prevent catalyst from falling off the catalyst bed 200. That is, preferably, the flow equalization layer 310 is configured to support the catalyst bed 200.

[0036] More preferably, the flow equalization layer 310 is configured to disperse the mixed hydrogen gas and reaction liquid into multiple streams that are sprayed upwards onto the catalyst bed 200, and the hydrogen gas in the streams contacts the catalyst bed 200 in the form of bubble aeration. In this way, the hydrogen gas and the reaction liquid mixed with it can more fully contact the solid catalyst on the catalyst bed 200, thereby effectively avoiding liquid-phase channeling and short-circuiting phenomena.

[0037] In a preferred embodiment, the flow equalization layer 310 is provided with microspheres having a plurality of channels facing the catalyst bed 200, thereby allowing the reaction liquid introduced from the inlet 1003 and the feed inlet 1004 to flow toward and subsequently contact the catalyst located in the catalyst bed 200. For example, in one example, the flow equalization layer 310 is implemented as a plurality of porous ceramic spheres.

[0038] In one embodiment, the distribution member 300 includes a liquid distribution assembly 400, which includes an injector 410. The injector 410 has a release port 4001 communicating with the air inlet 1003 and the feed inlet 1004. The release port 4001 is held in the chamber 1001 and located below the catalyst bed 200 and below the distribution member 300. Hydrogen introduced through the air inlet 1003 and the reaction liquid introduced through the feed inlet 1004 are mixed by the liquid distribution assembly 400 and discharged through the release port 4001, thus uniformly contacting the catalyst on the catalyst bed 200 by radial and axial splitting.

[0039] Those skilled in the art will understand that the injector 410 can fully mix hydrogen and reaction liquid, thereby making the hydrogen mixed in the reaction liquid more uniform, and thus enabling the mixture discharged from the distribution member to fully and uniformly contact the catalyst on the catalyst bed 200, thereby effectively avoiding liquid phase channeling and short-circuiting phenomena.

[0040] Preferably, the injector 410 is disposed in the chamber 1001 of the reactor 100.

[0041] More preferably, the injector 410 is arranged below the flow equalization layer 310, and the release port 4001 of the injector 410 is positioned facing the flow equalization layer 310; in this way, the injector 410 can not only fully mix hydrogen and reaction liquid, but also rapidly inject the mixed liquid into the flow equalization layer 310; and the flow equalization layer 310, on the one hand, uniformly splits the mixed liquid radially and axially for a second time, thereby fully contacting the catalyst on the catalyst bed 200.

[0042] It is worth mentioning that the liquid distribution assembly 400 includes a circulation pump 420, which is connected to the feed inlet 1004. The circulation pump 420 pressurizes the reaction liquid and introduces it into the injector 410, thereby allowing more hydrogen to be carried into the reaction liquid, thus ensuring sufficient contact between the reaction liquid, hydrogen, and the catalyst on the catalyst bed 200. Simultaneously, the injector 410 can also uniformly distribute the reaction liquid, thereby improving the uniformity of its contact with the catalyst on the catalyst bed 200. In a preferred embodiment, when the flow equalization layer 310 is provided, the flow equalization layer 310 can also reduce the impact force of the liquid ejected by the injector 410, thereby protecting the catalyst bed 200.

[0043] refer to Figure 2Furthermore, the reaction assembly for monochloroacetic acid includes a reaction liquid separation tank 500, wherein the reaction liquid separation tank 500 has a communication port 5001 communicating with the reactor 100 and a gas outlet 5002, wherein the communication port 5001 is connected to the discharge port 1002, and the gas outlet 5002 is used to discharge by-product gas.

[0044] Preferably, the gas outlet 5002 of the reaction liquid separation tank 500 is provided with a demister 510, so that the reaction liquid carried in the by-product gas overflowing through the gas outlet 5002 can be intercepted by the demister 510 and fall back into the reaction liquid separation tank 500.

[0045] In a preferred embodiment, the monochloroacetic acid reaction assembly further includes a non-condensable gas condenser 600, wherein the non-condensable gas condenser 600 is configured to condense the gaseous reaction liquid in the by-product gas flowing out of the gas outlet 5002, thereby further trapping the reaction liquid entrained in the by-product gas.

[0046] In a preferred embodiment, the monochloroacetic acid reaction assembly includes a non-condensable gas separator 700 and a gas assembly 800, wherein the non-condensable gas separator 700 is connected to the gas outlet 5002 of the reaction liquid separator 500; wherein the gas assembly 800 is configured to introduce inert gas or nitrogen into the non-condensable gas separator 700 from bottom to top, thereby stripping HCl gas from the non-condensable gas separator 700. The top of the non-condensable gas separator 700 has a gas outlet 7001 to discharge the stripped HCl gas. In a preferred embodiment, the discharged HCl gas is introduced into an HCl absorption tower.

[0047] Preferably, the bottom of the non-condensable gas separator 700 is connected to the reaction liquid separator 500.

[0048] In a preferred embodiment, the gas assembly 800 includes a gas conduit 810, wherein the gas conduit 810 is in communication with the bottom of the noncondensable gas separator 700 to strip HCl located in the noncondensable gas condenser 700 by introducing the inert gas or nitrogen.

[0049] In a preferred embodiment, the monochloroacetic acid reaction assembly includes a flow regulating component 910, wherein the flow regulating component 910 includes a flow regulating channel 911 communicating with the reaction liquid separation tank 500 and a flow regulating valve 912 disposed in the flow regulating channel 911.

[0050] Similarly, in a preferred embodiment, the monochloroacetic acid reaction assembly includes a temperature control component 920, wherein the temperature control component 920 includes a reaction liquid channel 921, a reaction liquid regulating valve 922 disposed in the reaction liquid channel 921, and a temperature control device 923, wherein the reaction liquid channel 921 is connected to the reaction liquid separation tank 500 and the feed inlet 1004, wherein the reaction liquid in the reaction liquid channel 921 is configured to exchange heat with the temperature control device 923, and then mixed with the reaction liquid before entering the reactor 100 from the feed inlet 1004, and then introduced together into the reactor 100.

[0051] Those skilled in the art will understand that, in this way, the temperature of the reaction liquid introduced into the reactor 100 can be adjusted.

[0052] Preferably, the temperature of the reaction liquid introduced into the reactor 100 is controlled between 130°C and 180°C. Preferably, the molar ratio of hydrogen to dichloroacetic acid in the reaction liquid is 1 to 5:1.

[0053] Those skilled in the art should understand that the embodiments of this application described above and shown in the accompanying drawings are merely examples and do not limit the scope of this application. The advantages of this application have been fully and effectively implemented. The functional and structural principles of this application have been demonstrated and explained in the embodiments, and any variations or modifications can be made to the implementation of this application without departing from the stated principles.

Claims

1. A reaction assembly for monochloroacetic acid, characterized in that, The reaction components for the monochloroacetic acid include: A reactor having a lower end and a higher end above the lower end, the reactor forming a chamber between the higher end and the lower end, wherein the lower end of the reactor has an air inlet and a feed inlet communicating with the chamber, and wherein the higher end of the reactor has a discharge outlet communicating with the chamber. A catalyst bed for supporting the catalyst for the hydrodechlorination reaction of dichloroacetic acid, wherein the catalyst bed is filled in the chamber and held at the upper end, and located in the flow path of the mixed hydrogen and reaction liquid to the outlet; A distribution member; wherein the distribution member is configured to uniformly contact the catalyst on the catalyst bed by splitting the hydrogen introduced from the gas inlet and the reaction liquid introduced from the feed inlet in the radial and axial directions, and then guide them from bottom to top to the discharge port of the high-end section.

2. The reaction assembly for monochloroacetic acid according to claim 1, characterized in that, The distribution component includes a flow equalization layer configured to uniformly distribute hydrogen introduced from the gas inlet and reaction liquid introduced from the feed inlet via the flow equalization layer in a radial and axial direction.

3. The reaction assembly for monochloroacetic acid according to claim 1, characterized in that, The distribution component includes a liquid distribution assembly, which includes an injector, wherein the injector has a release port communicating with the air inlet and the feed inlet, the release port being held in the chamber and located below the catalyst bed, wherein the release port is positioned toward the catalyst bed.

4. The reaction assembly for monochloroacetic acid according to claim 2, characterized in that, The distribution component includes a liquid distribution assembly, which includes an injector having a release port communicating with the air inlet and the feed inlet. The release port is held in the chamber and located below the catalyst bed, wherein the release port is positioned toward the flow equalization layer.

5. The reaction assembly for monochloroacetic acid according to claim 3 or 4, characterized in that, The liquid distribution assembly includes a circulation pump, wherein the circulation pump and the feed inlet are connected.

6. The reaction assembly for monochloroacetic acid according to claim 2, characterized in that, The flow equalization layer is configured to disperse the mixed hydrogen and reaction liquid into multiple streams that are sprayed upwards onto the catalyst bed, and the hydrogen in the streams contacts the catalyst bed in the form of bubble aeration.

7. The reaction assembly for monochloroacetic acid according to claim 2, characterized in that, The flow equalization layer is implemented as a plurality of ceramic spheres with channels.

8. The reaction assembly for monochloroacetic acid according to claim 1, characterized in that, The reaction assembly for monochloroacetic acid includes a reaction liquid separation tank, wherein the reaction liquid separation tank has a connection port communicating with the reactor and a gas outlet, wherein the connection port is connected to the discharge port and the gas outlet is used to discharge by-product gas.

9. The reaction assembly for monochloroacetic acid according to claim 8, characterized in that, The reaction assembly for monochloroacetic acid includes a demister, wherein the demister is located at the gas outlet of the reaction liquid separation tank.

10. The reaction assembly for monochloroacetic acid according to claim 8, characterized in that, The monochloroacetic acid reaction assembly also includes a non-condensable gas condenser, wherein the non-condensable gas condenser is configured to condense the gaseous reaction liquid in the by-product gas flowing out of the gas outlet to prevent it from being carried out by the non-condensable gas.

11. The reaction assembly for monochloroacetic acid according to claim 8, characterized in that, The reaction assembly for monochloroacetic acid includes a noncondensable gas separator and a gas assembly, wherein the noncondensable gas separator is connected to the gas outlet of the reaction liquid separator; wherein the gas assembly is configured to fill the noncondensable gas separator with inert gas or nitrogen from bottom to top, and the top of the noncondensable gas separator has a gas outlet.

12. The reaction assembly for monochloroacetic acid according to claim 11, characterized in that, The bottom of the non-condensable gas separator is connected to the reaction liquid separator.

13. The reaction assembly for monochloroacetic acid according to claim 8, characterized in that, The reaction assembly for monochloroacetic acid includes a flow regulating component, wherein the flow regulating component includes a flow regulating channel communicating with the reaction liquid separation tank and a flow regulating valve disposed in the flow regulating channel.

14. The reaction assembly for monochloroacetic acid according to claim 8, characterized in that, The reaction assembly for monochloroacetic acid includes a temperature control component, wherein the temperature control component includes a reaction liquid channel, a reaction liquid regulating valve disposed in the reaction liquid channel, and a temperature control device, wherein the reaction liquid channel is connected to the reaction liquid separation tank and the feed inlet, wherein the reaction liquid located in the reaction liquid channel is configured to exchange heat with the temperature control device, and then mixed with the reaction liquid before entering the reactor from the feed inlet, and then introduced into the reactor together.

15. The reaction assembly for monochloroacetic acid according to claim 8, characterized in that, The catalyst is implemented as a palladium catalyst placed on activated carbon, wherein the palladium content is 0.1% to 5%.

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