Device and process improvement method for preparing BYD from low-concentration formaldehyde solution

Abstract

The invention relates to the technical field of BYD preparation, and discloses a device for preparing BYD from a low-concentration formaldehyde solution and a process improvement method.The device comprises a formaldehyde generation unit and a BYD generation unit, the formaldehyde generation unit comprises an evaporator and a formaldehyde reactor communicated with the evaporator, and the formaldehyde reactor is communicated with a waste heat boiler; one side of the waste heat boiler is connected with a double-tower absorption assembly; the formaldehyde reactor comprises a mixing chamber and an oxidizing chamber arranged in the mixing chamber; the BYD generation unit comprises a reaction assembly and a power pump connected to one side of the reaction assembly, the other end of the power pump is connected with a filter, one side of the filter is connected with a BYD rectifying tower, and the other side of the BYD rectifying tower is connected with a formaldehyde rectifying tower; the double-tower absorption assembly comprises a first absorption tower and a second absorption tower arranged on one side of the first absorption tower; the problems that in the prior art, formaldehyde needs to be concentrated, the raw material consumption is large, the energy consumption is large, and the BYD production cost is high are solved.

Description

Technical Field

[0001] This invention relates to the field of BYD preparation technology, specifically to an apparatus and improved process method for preparing BYD from a low-concentration formaldehyde solution. Background Technology

[0002] The acetylacetonate process, also known as the Reppe process, is the mainstream industrial technology for preparing 1,4-butynediol (BYD). Its core involves the reaction of formaldehyde and acetylene with a copper-based catalyst, such as copper acetylacetonate or copper-bismuth catalysis, to produce BYD. This process is typically carried out under pressure of 1-20 bar and heating at 110-112°C. Formaldehyde concentration is a critical parameter in the preparation of 1,4-butynediol, directly affecting the selectivity of the main product, 1,4-butynediol, and the amount of the byproduct, propynyl alcohol. Higher formaldehyde concentrations, such as above 50%, can increase the reaction rate and product yield while reducing side reactions. Low moisture content can suppress the formation of byproducts, such as formic acid, ensuring the purity of BYD. Therefore, currently, industrially, 51% formaldehyde is mainly used as the production raw material, which is diluted during the production process before entering the BYD reactor.

[0003] This process first requires concentrating formaldehyde to a concentration of 51%, and then diluting it with a low-concentration formaldehyde solution before it enters the BYD reactor. The concentration process requires a large amount of energy and produces a low concentration of formaldehyde, resulting in high raw material consumption, high production energy consumption, and high BYD production costs. Summary of the Invention

[0004] To address the problems of high raw material consumption, high energy consumption, and high production cost of BYD caused by the need for formaldehyde concentration in the existing technology, this invention provides an apparatus and process improvement method for preparing BYD from low-concentration formaldehyde solution. This invention is achieved through the following technical solution.

[0005] An apparatus for preparing BYD from low-concentration formaldehyde solution includes a formaldehyde generation unit and a BYD generation unit. The formaldehyde generation unit includes an evaporator and a formaldehyde reactor connected to the evaporator, and a waste heat boiler is connected to the formaldehyde reactor. A double-tower absorption assembly is connected to one side of the waste heat boiler. The formaldehyde reactor includes a mixing chamber and an oxidation chamber disposed inside the mixing chamber. The BYD generation unit includes a reaction component and a power pump connected to one side of the reaction component. The other end of the power pump is connected to a filter. One side of the filter is connected to a BYD distillation column, and the other side of the BYD distillation column is connected to a formaldehyde distillation column.

[0006] As a preferred embodiment of the present invention, the dual-tower absorption assembly includes a first absorption tower and a second absorption tower disposed on one side of the first absorption tower. A first pipe is disposed between the upper side of the first absorption tower and the lower end of the second absorption tower, and a second pipe is disposed between the upper end of the first absorption tower and the side of the second absorption tower.

[0007] As a preferred embodiment of the present invention, the reaction assembly includes a reaction vessel and a mixing component installed inside the reaction vessel. A feed component is connected to one side of the reaction vessel, and a third pipe is connected to the other side of the reaction vessel opposite to the feed component.

[0008] As a preferred embodiment of the present invention, three reaction vessels are provided and connected in series, and the third pipeline connects multiple reaction vessels connected in series.

[0009] As a preferred embodiment of the present invention, the feeding component includes an air inlet pipe and an air inlet ring pipe connected to one end of the air inlet pipe, and an air outlet pipe is connected to the other side of the air inlet ring pipe. A fixing ring is provided on the outer side of the air inlet ring pipe, and the fixing ring is fixedly connected to the inside of the reactor.

[0010] As a preferred embodiment of the present invention, the mixing component includes a drive motor and a stirring shaft connected to one end of the drive motor, and stirring blades are evenly spaced on the outer side of the stirring shaft.

[0011] An improved process for preparing a BYD device using a low-concentration formaldehyde solution includes the following steps: Step 1: Methanol, air and water vapor are introduced into the evaporator to form a ternary gas mixture. The ternary gas mixture then enters the formaldehyde reactor and is oxidized at 600-700℃ by an electrolytic silver catalyst to produce formaldehyde gas. Step 2: The formaldehyde gas generated in Step 1 is rapidly cooled to below 230°C by a waste heat boiler, and then further cooled to 80-100°C; After cooling, the gas enters the dual-tower absorption assembly: in the first absorption tower, the dilute formaldehyde solution output from the second absorption tower is used as the absorbent, and the gas is fed from the top of the tower and contacts the gas in a counter-current manner; in the second absorption tower, soft water is used as the absorbent to absorb residual formaldehyde; the circulating liquid in the first absorption tower is recycled after being cooled and controlled by a cooler. A formaldehyde solution of 37% to 42% is produced from the bottom of the first absorption tower; Step 3: The 37%–42% formaldehyde solution obtained in Step 2 and acetylene are introduced into the reaction assembly. Under the action of a copper-bismuth catalyst, they react to generate BYD, and the formaldehyde content in the reaction product is controlled to be <3 wt%. Step 4: The reaction solution is separated from the catalyst, filtered, and distilled to remove residual formaldehyde, propynyl alcohol, and methanol, yielding qualified BYD products.

[0012] In a preferred embodiment of the present invention, the purity of the electrolytic silver catalyst in step one is 99.99%, the oxygen-to-alcohol ratio is controlled at 0.38, and water vapor is added according to a 60% concentration of the feedstock.

[0013] As a preferred embodiment of the present invention, in the dual-tower absorption assembly of step two, the circulating liquid in the first absorption tower is maintained at a temperature of less than or equal to 40°C by a cooler.

[0014] In a preferred embodiment of the present invention, the formaldehyde solution concentration in step three reaches 37% to 42%, which can be directly used as a raw material for BYD synthesis without the need for concentration.

[0015] The present invention has the following beneficial effects: 1. By setting up a formaldehyde generation unit, a formaldehyde solution with a concentration of 37% to 42% can be obtained; then, it is introduced into the BYD generation unit, and by using the reaction components and the BYD distillation column, a qualified BYD solution can be directly generated; in this process, there is no need to concentrate the formaldehyde solution, which saves equipment investment in BYD production and saves energy consumption such as steam and hot water.

[0016] 2. By setting up reaction components and connecting multiple sets of reaction vessels through a third pipeline, it is possible to more easily connect multiple sets of reaction vessels in series, and it is also convenient to disassemble and maintain them, saving working time; when needed, more reaction vessels can be added in series to meet production requirements.

[0017] 3. By setting up the BYD generation unit and using powdered copper bismuth catalyst, the formaldehyde content in the final BYD solution is less than 3wt%. After filtration and purification, the BYD solution yields 47% BYD solution and 4% formaldehyde wastewater. Compared with formaldehyde wastewater with a formaldehyde concentration of 17% produced by concentrating formaldehyde to a 51% concentration, the wastewater in this process has a lower formaldehyde content and lower wastewater treatment costs, thus saving costs. Attached Figure Description

[0018] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 : A schematic diagram of the overall structure of the present invention; Figure 2 : A schematic diagram of the structure of the dual-tower absorption assembly in this invention; Figure 3 : A schematic diagram of the structure of the reaction component in this invention; Figure 4 : A schematic cross-sectional view of the reaction vessel in this invention; Figure 5 This invention Figure 4 Enlarged structural diagram at point A; Figure 6 : A schematic diagram of the structure of the hybrid component in this invention; Figure 7 : A flowchart of the production process in this invention.

[0020] The attached figures are labeled as follows: 10. Formaldehyde generation unit; 11. Evaporator; 12. Formaldehyde reactor; 121. Mixing chamber; 122. Oxidation chamber; 13. Waste heat boiler; 14. Dual-tower absorption assembly; 141. First absorption tower; 142. Second absorption tower; 143. First pipeline; 144. Second pipeline; 20. BYD generation unit; 21. Reaction assembly; 211. Reactor; 212. Feeding component; 2121. Inlet pipe; 2122. Inlet ring pipe; 2123. Outlet pipe; 2124. Fixing ring; 213. Mixing component; 2131. Drive motor; 2132. Stirring shaft; 2133. Stirring blades; 214. Third pipeline; 22. Power pump; 23. Filter; 24. BYD distillation tower; 25. Formaldehyde distillation tower. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 Reference Figures 1-6 As shown in the first embodiment of the present invention, an apparatus for preparing BYD from low-concentration formaldehyde solution is provided, including a formaldehyde generation unit 10 and a BYD generation unit 20. The formaldehyde generation unit 10 includes an evaporator 11 and a formaldehyde reactor 12 connected to the evaporator 11, and a waste heat boiler 13 is connected to the formaldehyde reactor 12. A double-tower absorption assembly 14 is connected to one side of the waste heat boiler 13. The formaldehyde reactor 12 includes a mixing chamber 121 and an oxidation chamber 122 disposed inside the mixing chamber 121. The evaporator 11 is provided with a connection port, which can be used to introduce methanol and air respectively. The two are mixed in the evaporator 11 and then discharged from the evaporator 11. Before entering the formaldehyde reactor 12, they are mixed with water vapor to form a ternary gas mixture, which is then introduced into the formaldehyde reactor 12. The formaldehyde reactor 12 is provided with an oxidation chamber 122. The oxidation chamber 122 is used to control the reaction of the ternary gas mixture to generate formaldehyde. By introducing the waste heat boiler 13, the gas converted by the formaldehyde reactor 12 is fed into the waste heat boiler 13 to control the occurrence of side reactions and prevent the decomposition of methanol. At the same time, the gas is cooled to below 230°C, and then cooled to 80~100°C in the cooling section before entering the double tower absorption assembly 14.

[0023] The dual-tower absorption assembly 14 includes a first absorption tower 141 and a second absorption tower 142 disposed on one side of the first absorption tower 141. A first pipe 143 is disposed between the upper side of the first absorption tower 141 and the lower end of the second absorption tower 142, and a second pipe 144 is disposed between the upper end of the first absorption tower 141 and the side of the second absorption tower 142. The first absorption tower 141 and the second absorption tower 142 are connected by a first pipe 143 and a second pipe 144, allowing gas and liquid to flow through them. A cooler is installed on the first absorption tower 141 so that the circulating liquid coming out of the first absorption tower 141 is cooled by the cooler before being pumped into the middle of the tower. Meanwhile, the unabsorbed gas is led out from the top of the tower through the first pipe 143 and enters the bottom of the second absorption tower 142, and is led out from the top of the tower.

[0024] BYD generation unit 20 includes reaction component 21 and power pump 22 connected to one side of reaction component 21. The other end of power pump 22 is connected to filter 23. One side of filter 23 is connected to BYD distillation column 24, and the other side of BYD distillation column 24 is connected to formaldehyde distillation column 25. One end of the reaction component 21 is connected to the dual-tower absorption component 14. The formaldehyde solution generated in the dual-tower absorption component 14 reacts with acetylene in the reaction component 21 to generate butynediol (BYD). The solution is then pumped by the power pump 22 into the filter 23 for filtration. The filtered turbid liquid is returned to the reaction component 21. The filtered solution is then fed into the BYD distillation column 24 and the formaldehyde distillation column 25 for final purification. All components are connected by pipes.

[0025] The reaction assembly 21 includes a reaction vessel 211 and a mixing component 213 installed inside the reaction vessel 211. A feed component 212 is connected to one side of the reaction vessel 211, and a third pipe 214 is connected to the other side of the reaction vessel 211 opposite to the feed component 212. The reactor 211 consists of three reactors connected in series. Alternatively, four or other reactors 211 can be installed, depending on actual production requirements. A third pipe 214 connects multiple reactors 211 connected in series, with one end of the third pipe 214 connected to the inside of the reactor 211. Both the feed component 212 and the mixer 213 are installed inside the reactor 211. Acetylene is introduced through the feed component 212, while the mixer 213 mixes and stirs the formaldehyde and acetylene in the reactor 211, allowing them to react fully within the reactor 211. Among them, the reactor 211 uses a jacket for heat dissipation. The heat generated inside the equipment is removed by the cooling medium flowing in the jacket structure wrapped around the outer wall of the reactor 211.

[0026] The feed component 212 includes an air inlet pipe 2121 and an air inlet ring pipe 2122 connected to one end of the air inlet pipe 2121. An air outlet pipe 2123 is connected to the other side of the air inlet ring pipe 2122. A fixing ring 2124 is provided on the outer side of the air inlet ring pipe 2122 and the fixing ring 2124 is fixedly connected to the inside of the reactor 211. The intake pipe 2121 is installed on the reactor 211. One end of the intake pipe is connected to acetylene, and the other end is located inside the reactor 211 and is connected to the intake ring pipe 2122. The intake ring pipe 2122 is fixedly installed inside the reactor 211 by a fixing ring 2124. The fixing ring 2124 is fixedly installed inside the reactor 211 and is integrally formed with the reactor 211. The fixing rings 2124 are evenly distributed inside the reactor 211 to make the installation of the intake ring pipe 2122 more secure. The air inlet ring pipe 2122 is filled with Raschig rings to reduce the partial pressure of acetylene. An air outlet pipe 2123 is connected to the air inlet ring pipe 2122, and the air outlet pipes 2123 are evenly distributed on the air inlet ring pipe 2122. The other end of the air inlet ring pipe 2122 extends into the bottom of the reactor 211. The arrangement of the air inlet pipe 2121, air inlet ring pipe 2122 and air outlet pipe 2123 allows acetylene to be evenly introduced into the reactor 211, facilitating its reaction with the formaldehyde solution.

[0027] The mixing unit 213 includes a drive motor 2131 and a stirring shaft 2132 connected to one end of the drive motor 2131, and stirring blades 2133 are evenly spaced on the outer side of the stirring shaft 2132. The drive motor 2131 is installed at the upper end of the reaction vessel 211 and connected to the stirring shaft 2132. The drive motor 2131 and the stirring shaft 2132 can be fixedly connected by threads. The stirring blades 2133 are fixedly connected to the stirring shaft 2132 and are evenly distributed on the stirring shaft 2132 to facilitate the mixing of formaldehyde and acetylene in the reaction vessel 211.

[0028] Example 2 Reference Figure 7 As shown, this is the second embodiment of the present invention, a process improvement method for preparing a BYD device from a low-concentration formaldehyde solution, comprising the following steps: Step 1: Methanol, air and water vapor are introduced into evaporator 11 to form a ternary gas mixture. The ternary gas mixture then enters formaldehyde reactor 12 and is oxidized to formaldehyde gas by electrolytic silver catalyst at 600-700℃. Step 2: The formaldehyde gas generated in Step 1 is rapidly cooled to below 230°C by waste heat boiler 13, and then further cooled to 80-100°C; After cooling, the gas enters the dual-tower absorption assembly 14: In the first absorption tower 141, the dilute formaldehyde solution output from the second absorption tower 142 is used as the absorbent, and the gas is fed from the top of the tower and contacts the gas in the opposite direction; in the second absorption tower 142, soft water is used as the absorbent to absorb residual formaldehyde; the circulating liquid in the first absorption tower 141 is recycled after being cooled by a cooler. A formaldehyde solution of 37% to 42% is produced from the bottom of the first absorption tower 141; Step 3: The 37%–42% formaldehyde solution obtained in Step 2 and acetylene are introduced into reaction assembly 21. Under the action of a copper-bismuth catalyst, they react to generate BYD, and the formaldehyde content in the reaction product is controlled to be <3 wt%. Step 4: The reaction solution is separated from the catalyst, filtered, and distilled to remove residual formaldehyde, propynyl alcohol, and methanol, yielding qualified BYD products.

[0029] In step one, the purity of the electrolytic silver catalyst is 99.99%, the oxygen-to-alcohol ratio is controlled at 0.38, and water vapor is added according to the proportion of 60% of the feed concentration; in step two, in the dual-tower absorption assembly 14, the circulating liquid in the first absorption tower 141 is kept at a temperature of less than or equal to 40°C by a cooler; in step three, the copper-bismuth catalyst is in powder form; in step three, the formaldehyde solution concentration reaches 37% to 42%, and it is directly used as a raw material for BYD synthesis without the need for concentration; In the oxidation chamber 122, the ternary reactive gas undergoes oxidation and dehydrogenation reactions under the action of electrolytic silver catalyst to generate formaldehyde. The reaction temperature is controlled at 650℃, and most of the methanol is converted into formaldehyde. At the same time, some side reactions occur. In order to control the occurrence of side reactions and prevent the decomposition of methanol, the converted gas waste heat boiler 13 is cooled to below 230℃, and then cooled to 80~100℃ in the cooling section before entering the double tower absorption component 14. The absorption process employs a dual-tower circulation system. The second absorption tower 142 uses soft water as the absorbent, while the first absorption tower 141 uses a dilute formaldehyde solution from the second absorption tower 142 as the absorbent. Self-cooled formaldehyde enters the first absorption tower 141 from the bottom and flows towards the top. The dilute formaldehyde solution from the second absorption tower 142 is added from the top, and the circulating liquid from the first absorption tower 141 is added from the middle of the tower, flowing downwards, with the airflow in opposite directions. During this operation, most of the formaldehyde is absorbed, releasing a large amount of heat. To control the main tower circulation temperature and ensure absorption efficiency, the circulating liquid from the first absorption tower 141 must pass through a cooler before being pumped into the middle of the tower and then circulates within the tower. The water used for absorption is pumped to the top of the second absorption tower 142 via a cooler. After formaldehyde is absorbed in the second absorption tower 142, it is cooled by a pump and then pumped to the top of the first absorption tower 141. After further absorption of formaldehyde in the first absorption tower 141, a formaldehyde solution with a concentration of about 37% to 42% is collected from the bottom of the first absorption tower 141.

[0030] In this process, acetylene reacts with a 37%–42% formaldehyde solution in reaction unit 21 to produce butynediol (BYD), using a powdered copper-bismuth catalyst. The formaldehyde content in the final BYD solution is less than 3 wt%. After separation from the catalyst slurry, the BYD solution passes through BYD distillation column 24 and formaldehyde distillation column 25 to remove excess formaldehyde, propynyl alcohol, and methanol from the crude BYD solution, generating a qualified BYD solution that is then sent to the next process.

[0031] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An apparatus for preparing BYD from a low-concentration formaldehyde solution, characterized in that: The device includes a formaldehyde generation unit (10) and a BYD generation unit (20). The formaldehyde generation unit (10) includes an evaporator (11) and a formaldehyde reactor (12) connected to the evaporator (11). A waste heat boiler (13) is connected to the formaldehyde reactor (12), and a double-tower absorption assembly (14) is connected to one side of the waste heat boiler (13). The formaldehyde reactor (12) includes a mixing chamber (121) and an oxidation chamber (122) disposed inside the mixing chamber (121). The BYD generation unit (20) includes a reaction component (21) and a power pump (22) connected to one side of the reaction component (21). The other end of the power pump (22) is connected to a filter (23). One side of the filter (23) is connected to a BYD distillation column (24), and the other side of the BYD distillation column (24) is connected to a formaldehyde distillation column (25).

2. The apparatus for preparing BYD from low-concentration formaldehyde solution according to claim 1, characterized in that: The dual-tower absorption assembly (14) includes a first absorption tower (141) and a second absorption tower (142) disposed on one side of the first absorption tower (141). A first pipe (143) is disposed between the upper side of the first absorption tower (141) and the lower end of the second absorption tower (142). A second pipe (144) is disposed between the upper end of the first absorption tower (141) and the side of the second absorption tower (142).

3. The apparatus for preparing BYD from low-concentration formaldehyde solution according to claim 2, characterized in that: The reaction assembly (21) includes a reaction vessel (211) and a mixing component (213) installed inside the reaction vessel (211). A feed component (212) is connected to one side of the reaction vessel (211), and a third pipe (214) is connected to the other side of the reaction vessel (211) opposite to the feed component (212).

4. The apparatus for preparing BYD from low-concentration formaldehyde solution according to claim 3, characterized in that: There are three reactors (211) connected in series, and the third pipe (214) connects multiple reactors (211) connected in series.

5. The apparatus for preparing BYD from low-concentration formaldehyde solution according to claim 4, characterized in that: The feed component (212) includes an air inlet pipe (2121) and an air inlet ring pipe (2122) connected to one end of the air inlet pipe (2121). An air outlet pipe (2123) is connected to the other side of the air inlet ring pipe (2122). A fixing ring (2124) is provided on the outside of the air inlet ring pipe (2122), and the fixing ring (2124) is fixedly connected to the inside of the reactor (211).

6. The apparatus for preparing BYD from low-concentration formaldehyde solution according to claim 5, characterized in that: The mixing component (213) includes a drive motor (2131) and a stirring shaft (2132) connected to one end of the drive motor (2131), and stirring blades (2133) are evenly spaced on the outer side of the stirring shaft (2132).

7. An improved method for preparing a BYD device using a low-concentration formaldehyde solution as described in any one of claims 1 to 6, characterized in that: Includes the following steps, Step 1: Methanol, air and water vapor are introduced into the evaporator (11) to form a ternary gas mixture. The ternary gas mixture then enters the formaldehyde reactor (12) and is oxidized by electrolytic silver catalyst at 600-700°C to generate formaldehyde gas. Step 2: The formaldehyde gas generated in Step 1 is rapidly cooled to below 230°C by a waste heat boiler (13), and then further cooled to 80-100°C; After cooling, the gas enters the dual-tower absorption assembly (14): in the first absorption tower (141), the dilute formaldehyde solution output from the second absorption tower (142) is used as the absorbent, and the gas is fed from the top of the tower and contacts the gas in the opposite direction; in the second absorption tower (142), soft water is used as the absorbent to absorb the residual formaldehyde. The circulating liquid in the first absorption tower (141) is recycled after being cooled and controlled by a cooler. A formaldehyde solution of 37% to 42% is produced from the bottom of the first absorption tower (141); Step 3: The 37%–42% formaldehyde solution obtained in Step 2 and acetylene are introduced into the reaction assembly (21) and reacted under the action of a copper-bismuth catalyst to generate BYD. The formaldehyde content in the reaction product is controlled to be <3 wt%. Step 4: The reaction solution is separated from the catalyst, filtered, and distilled to remove residual formaldehyde, propynyl alcohol, and methanol, yielding qualified BYD products.

8. The improved process method for preparing BYD using a low-concentration formaldehyde solution according to claim 7, characterized in that: In step one, the purity of the electrolytic silver catalyst is 99.99%, the oxygen-to-alcohol ratio is controlled at 0.38, and water vapor is added according to the proportion of 60% of the feed concentration.

9. The improved process method for preparing BYD using a low-concentration formaldehyde solution according to claim 7, characterized in that: In the dual-tower absorption assembly (14) of step two, the circulating liquid of the first absorption tower (141) is kept at a temperature of less than or equal to 40°C by a cooler.

10. The improved process method for preparing BYD apparatus using low-concentration formaldehyde solution according to claim 7, characterized in that: In step three, the formaldehyde solution concentration reaches 37% to 42%, which can be directly used as a raw material for BYD synthesis without the need for concentration.

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