Process for separating sugar and acid by using three-area simulated moving bed

Abstract

The invention discloses a process for separating sugar and acid by a three-zone simulated moving bed. The three-zone simulated moving bed is formed by more than four resin columns filled with H-type cation exchange resin in a looping manner, every 1-6 resin columns form one zone, and the three zones are sequentially an adsorption separation zone III, an acid enrichment zone II and a desorption regeneration zone I; the resin columns in the three areas are respectively connected in series, more than two resin columns are arranged in the adsorption separation area III, and the resin columns comprise a first resin column and a second resin column which are connected in series; an outlet of the desorption regeneration area I is communicated with an inlet of the acid enrichment area II, and an outlet of the acid enrichment area II and an outlet of the first resin column in the adsorption separation area III are connected to an inlet of the second resin column in parallel; the three-zone simulated moving bed is used for separating sugar and acid in the lignocellulose hydrolysis sugar liquid containing the inorganic acid.

Description

Technical Field

[0001] The present invention relates to the fields of biochemical engineering and bioenergy, and in particular to a process for separating sugar and acid using a three-zone simulated moving bed. Background Art

[0002] Lignocellulosic biomass is considered a potential alternative to fossil fuels due to its abundant reserves, low cost, and ability to serve as a sugar platform feedstock for the production of biofuels and biochemicals. Converting biomass to sugars via inorganic acid hydrolysis offers the advantages of high efficiency and low cost. However, the high content of inorganic acids in the subsequent sugar solution inhibits microbial growth and / or metabolism, posing a significant challenge to its use as a fermentation carbon source.

[0003] Currently, a large number of processes based on sugar-acid separation have been reported in the literature, mainly including ion exclusion chromatography, solvent extraction, electrodialysis, and alkali salt neutralization. The above methods all have certain advantages and disadvantages. For example, solvent extraction is simple to operate, but there is the problem of organic phase entrainment and the reaction and consumption of acid and organic reagents during the process; electrodialysis has good sugar-acid separation effect at low concentrations, but the separation efficiency decreases at higher concentrations; ammonia or sodium hydroxide is simple to operate when partially neutralizing the acidic medium, but other auxiliary treatments may be required to avoid the generation and accumulation of harmful compounds in the system; anion exchange resin can usually achieve very good separation between sugars and acids, but due to the need for elution medium, the sugar or acid flow will be diluted during the separation process. Therefore, the present invention develops a three-zone simulated moving bed process for separating sugars and acids to achieve efficient separation of sugars and acids while ensuring high-concentration recovery of sugars and acids. Summary of the Invention

[0004] Purpose of the Invention: This invention addresses the shortcomings of existing technologies by providing a three-zone simulated moving bed process for separating sugars and acids. This process effectively addresses the difficulties in separating sugars and acids during the acid-based preparation of lignocellulose hydrolysates, including the high dilution of sugars and inorganic acids, low separation efficiency, complex separation processes, and high separation costs.

[0005] In order to solve the above technical problems, the present invention discloses the following technical solutions:

[0006] In a first aspect, the present invention discloses a three-zone simulated moving bed for separating sugars and acids.

[0007] The three-zone simulated moving bed is composed of a ring of more than 4 resin columns filled with H-type cation exchange resin, with 1 to 6 resin columns forming a zone. There are three zones, namely adsorption separation zone III, acid enrichment zone II, and desorption regeneration zone I.

[0008] The resin columns in the three zones are connected in series respectively, and the adsorption separation zone III is provided with more than two resin columns, including a first resin column and a second resin column connected in series.

[0009] The outlet of the desorption regeneration zone I is connected to the inlet of the acid enrichment zone II, and the outlet of the acid enrichment zone II and the outlet of the first resin column in the adsorption separation zone III are connected in parallel to the inlet of the second resin column.

[0010] Among them, a feed inlet is provided at the entrance of the adsorption separation zone III, that is, the entrance of the first resin, and an eluent inlet is provided at the entrance of the desorption regeneration zone I; a first feed liquid outlet is provided at the outlet of the adsorption separation zone III for recovering sugar, and a second feed liquid outlet is provided at the outlet of the desorption regeneration zone I for recovering acid.

[0011] The simulated moving bed further comprises an intermediate material storage tank, the outlet of the acid enrichment zone II and the outlet of the first resin column are connected in parallel to the intermediate material storage tank, and the intermediate material storage tank is connected in series with the second resin column.

[0012] The three-zone simulated moving bed is used to separate sugars and acids from a lignocellulose hydrolyzed sugar solution containing an inorganic acid. The total sugar concentration in the lignocellulose hydrolyzed sugar solution containing an inorganic acid is 10-200 g / L, such as 50 g / L, 100 g / L, 120 g / L, 140 g / L, 160 g / L, and 180 g / L. The sugars include glucose, xylose, and arabinose, with the glucose concentration being 70-80 g / L, the xylose concentration being 35-45 g / L, and the arabinose concentration being 3-10 g / L. The inorganic acid concentration in the lignocellulose hydrolyzed sugar solution containing an inorganic acid is 5-100 g / L, such as 15 g / L, 25 g / L, 35 g / L, 45 g / L, 55 g / L, and 65 g / L. The inorganic acid includes sulfuric acid.

[0013] The H-type cation exchange resin has a basic skeleton of styrene-divinylbenzene copolymer, a functional group of sulfonic acid, a cross-linking degree of 2-10%, a spherical shape, and a particle size of 0.42-1.2 mm. + The concentration is 4.8-5.6meq / dry gm and the humidity is 10.5-5%.

[0014] In a second aspect, the present invention discloses the use of the three-zone simulated moving bed for separating sugars and acids as described in the first aspect.

[0015] The application is specifically for separating sugars and acids from a lignocellulose hydrolyzed sugar solution containing inorganic acids. The resin columns in the three-zone simulated moving bed are switched sequentially from the adsorption separation zone III to the acid enrichment zone II and then to the desorption regeneration zone I.

[0016] Wherein, the use comprises the following steps:

[0017] S1: The lignocellulose hydrolyzed sugar solution containing inorganic acid is loaded from the inlet of the adsorption separation zone III (i.e., the inlet of the first column), and at the same time, the eluent is loaded from the inlet of the desorption regeneration zone I;

[0018] S2: The lignocellulose hydrolyzed sugar solution containing inorganic acid enters the adsorption separation zone III for adsorption separation, the resin column adsorbs the acid and separates the sugar, and the effluent at the outlet of the adsorption separation zone III is collected, i.e., the sugar-rich liquid;

[0019] After the resin column in the adsorption separation zone III is saturated with acid, it is moved out of the adsorption separation zone III and enters the acid enrichment zone II to enrich the inorganic acid and remove the residual sugar. The effluent obtained after the first resin column enters the acid enrichment zone II is an effluent containing sugar and acid. The effluent flows into the intermediate material storage tank, and the liquid in the intermediate material storage tank is pumped into the second resin column to repeat the adsorption separation;

[0020] After the resin column in the acid enrichment zone II removes the residual sugar, it is moved out of the acid enrichment zone II and enters the desorption regeneration zone I, where it is eluted with an eluent to remove the acid, and the effluent from the desorption regeneration zone I is collected, i.e., the acid-rich feed solution;

[0021] Repeat S2 to perform the cycle operation;

[0022] The system can be circulated and run continuously. When the operation is finished, the loading of the lignocellulose hydrolyzed sugar solution containing inorganic acid can be suspended, and the flow rate of the eluent can be increased until no sugar or acid is detected at the two discharge ports.

[0023] In step S1, the acid-containing lignocellulosic hydrolyzate is stored in an intermediate feed storage tank, and the sulfuric acid solution is stored in the acid-rich feed storage tank. This ensures that the resin is in liquid during the simulated moving bed operation during the initial operation, effectively preventing the resin from drying out and cracking in the column due to the lack of liquid, thereby affecting the sugar-acid separation effect. In some embodiments, the ratio of the concentration of sulfuric acid in the sulfuric acid solution to the concentration of sulfuric acid in the acid-containing lignocellulosic hydrolyzate is 1:0.8-1.2, such as 1:1.

[0024] In step S2, the effluent from the desorption regeneration zone I, i.e., the acid-rich feed liquid, is collected when the acid concentration in the effluent is balanced, and a portion of the effluent is retained in the acid-rich feed liquid storage tank to maintain dynamic equilibrium; the portion of the effluent is 1 / 4-1 / 50 of the total volume of the effluent, such as 1 / 10, 1 / 20, 1 / 30, 1 / 40.

[0025] Among them, the switching of each column is carried out synchronously.

[0026] Wherein, the eluent in the desorption regeneration zone (zone I) is water.

[0027] Among them, the first rate of loading the lignocellulose hydrolyzed sugar solution containing inorganic acid in the adsorption separation zone (zone III) (i.e., the flow rate of the feed inlet pump ③) is 1.2-12BV / h, such as 3BV / h, 3.5BV / h, 3.7BV / h, 4.0BV / h, 4.3BV / h, 5BV / h, 8BV / h, 10BV / h.

[0028] Wherein, the second rate of eluent elution in the desorption regeneration zone (zone I) (i.e., the flow rate of the discharge pump ①) is 5-40BV / h, such as 7BV / h, 8BV / h, 8.5BV / h, 9BV / h, 9.1BV / h, 9.3BV / h, 9.4BV / h, 9.5BV / h, 10BV / h, 15BV / h, 20BV / h.

[0029] Among them, the third rate at which the liquid in the intermediate material storage tank enters the second resin column (i.e., the flow rate of the feed inlet pump ④) is 2.4-35BV / h, such as 5BV / h, 7BV / h, 7.5BV / h, 8BV / h, 8.5BV / h, 9BV / h, 10BV / h, 15BV / h, 20BV / h.

[0030] Among them, the fourth rate (i.e., the flow rate of the feed inlet pump ②) of the acid-rich liquid entering the acid enrichment zone II is 2.4-30BV / h, such as 3BV / h, 5BV / h, 9BV / h, 15BV / h, 20BV / h; at the same time, the fourth rate (the flow rate of the feed inlet pump ②) satisfies: the second rate pump ①>the fourth rate pump ②, the fourth rate pump ②=the third rate pump ④-the first rate pump ③.

[0031] Among them, the column switching time is 5-40 minutes, such as 8 minutes, 10 minutes, 12 minutes, and 15 minutes.

[0032] The three-zone simulated moving bed and the process for separating sugars and acids provided by the present invention not only gradually accumulate the mass of sulfuric acid and sugar in the elution zone from a process perspective, eliminating the need for complete elution from a single column before proceeding to the next step, but also enhances the binding strength between the resin and the acid. Therefore, the present invention can increase the flow rate and still achieve a high separation effect during injection and elution at higher flow rates. For example, in the present invention, the injection volume is as high as 3.675 BV / h or more, the acid recovery rate is as high as 98.49%, the sugar recovery rate is as high as 97.11%, the acid dilution is as high as 75.78%, and the sugar dilution is as high as 74.20%.

[0033] Beneficial effects:

[0034] (1) The present invention realizes the effective separation of mineral acid and sugar components in lignocellulose hydrolyzate through a three-zone simulated moving bed process for separating sugar and acid.

[0035] (2) The sugar-acid separation process of the present invention is carried out at room temperature and pressure, and no additional energy is consumed.

[0036] (3) The resin used in the present invention can be reused through regeneration, and the processing volume per unit time is large, which can realize continuous and industrialized amplification production and effectively reduce industrial costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more apparent.

[0038] Figure 1 This is a flow chart for separating sugar and acid from acid-containing lignocellulosic biomass in an embodiment of the present invention.

[0039] Figure 2 This is a simulation of the switching sequence of moving bed columns in an embodiment of the present invention.

[0040] Figure 3 This is a real picture of the simulated moving bed in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The present invention can be better understood according to the following examples. However, it is easy for those skilled in the art to understand that the contents described in the examples are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims.

[0042] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.

[0043] The resins described in the following examples, unless otherwise specified, are all H-type cation exchange resins with styrene-divinylbenzene copolymer as the basic skeleton, sulfonic acid as the functional group, a cross-linking degree of 2-10%, spherical shape, and a particle size of 0.42-1.2 mm. + The concentration is 4.8meq / dry gm and the humidity is 1%.

[0044] The concentrations of the acid-containing lignocellulose hydrolyzate in the following examples are: 41.00 g / l sulfuric acid, 79.06 g / l glucose, 39.76 g / l xylose, 7.46 g / l arabinose, and 126.28 g / l total sugars.

[0045] In the following examples, 1 mol / l sodium hydroxide solution was used to neutralize and determine the acid content.

[0046] In the following examples, high performance liquid chromatography was used to detect sugars under the following conditions:

[0047] A Waters 2414 differential refractometer and a Bio-Rad Aminex HPX-87H HPLC column (300 × 7.8 mm; Bio-Rad Laboratories, Hercules, CA, USA) were used. The detector and column temperatures were controlled at 35°C and 55°C, respectively. The mobile phase was 5 mM sulfuric acid at a flow rate of 0.6 mL / min.

[0048] The recovery, dilution and purity of the acid and sugar in the experimental examples of the present invention are calculated as follows:

[0049] Recovery rate of target component % = mass of target collected liquid component / mass of target component to be separated;

[0050] Sugar purity % = (the sum of the concentrations of various sugars in the sugar-rich solution) / (the sum of the concentrations of various sugars in the sugar-rich solution + the concentration of acid in the sugar-rich solution);

[0051] Acid purity % = (acid concentration in acid-rich feed solution) / (acid concentration in acid-rich feed solution + sugar concentration in acid-rich solution);

[0052] Dilution % = concentration of target collected solution component / concentration of target component to be separated.

[0053] Example 1

[0054] A three-zone simulated moving bed process for separating sugars and acids operates as follows:

[0055] A continuous separation device system consisting of 10 resin columns ( Figure 1 , Figure 3 ), 10 columns form a closed-loop circulation system, in which each column is filled with 400 ml of resin and the radius of the resin column is 3.4 cm.

[0056] Store approximately 1L of acidic lignocellulose hydrolysate in the intermediate feed tank, and approximately 1L of 41.00g / L sulfuric acid solution in the acid-rich feed tank. Before starting the peristaltic pump, expel the air and waste liquid from the column pipes. Load the acidic lignocellulose hydrolysate, using pure water as the eluent. By switching the feed inlet and outlet positions, the resin column's state is altered.

[0057] The three zones are connected in series and switched in sequence in the direction of zone III → zone II → zone I → zone III. Each inlet and outlet is in a continuous injection state, that is, the inlet of zone III is continuously fed by pump ③, and the inlet of zone I is continuously fed with eluent water by pump 1. At the same time, in the initial reaction stage, pumps ② and ④ also introduce acid solution and hydrolyzate into column 7 of zone II and zone III, respectively, to prevent the resin from drying out in the initial operation stage, and effectively avoid the dilution of the acid-rich feed liquid and the sugar-rich feed liquid by the introduction of water. The sugar-rich solution is then collected at the outlet of zone III.

[0058] When the acid concentration in the effluent from the outlet of column 6 in zone III is half of the acid concentration in the feed liquid from the inlet of column 6 (the column replacement cycle is about 10 minutes), the column is moved forward into zone II through periodic switching, and the residual sugar in the column will further flow into the intermediate material storage tank and then flow into zone III for separation; the first column (column 3) corresponding to zone II enters zone I to complete desorption and regeneration, and collects the effluent from zone I, i.e., the acid-rich feed liquid; after regeneration, it is sent to the adsorption separation zone (zone III) for re-adsorption separation. This is a cyclic operation, and each cycle requires 10 steps of column switching, as shown in the following example. Figure 2 shown.

[0059] During operation, when the acid concentration in the acid-rich liquid is stable, the acid-rich liquid is collected and a little is retained in the recalculated liquid storage tank to ensure dynamic balance.

[0060] The flow rates of each pump are shown in Table 1. After approximately 200 hours of operation, the sugar solution processing volume reached 300 L. The concentration, purity, dilution, and recovery of the sugar and acid in the collected sugar-rich solution (417.53 L) and acid-rich solution (388.08 L) were measured and calculated, and the results are shown in Tables 2 and 3.

[0061] Table 1

[0062]

[0063] Table 2

[0064]

[0065] Table 3

[0066]

[0067] Example 2

[0068] The feed liquid to be separated and the operation were the same as in Example 1, and the flow rate of each pump was shown in Table 2 below.

[0069] Table 4

[0070]

[0071] Table 5

[0072]

[0073] Table 6

[0074]

[0075] Example 3

[0076] The liquid to be separated and the operation were the same as in Example 1, and the flow rates of the pumps were as shown in Table 3.

[0077] Table 7

[0078]

[0079] Table 8

[0080]

[0081] Table 9

[0082]

[0083] Example 4

[0084] The liquid to be separated and the operation were the same as in Example 1, and the flow rates of the pumps were shown in Table 4.

[0085] Table 10

[0086]

[0087] Table 11

[0088]

[0089] Table 12

[0090]

[0091] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A three-zone simulated moving bed for separating sugars and acids, characterized in that: The three-zone simulated moving bed is composed of a ring of more than 4 resin columns filled with H-type cation exchange resin, with 1 to 6 resin columns forming one zone, and is provided with three zones, namely, adsorption separation zone III, acid enrichment zone II, and desorption regeneration zone I. The resin columns in the three zones are connected in series respectively, and the adsorption separation zone III is provided with more than two resin columns, including a first resin column and a second resin column connected in series; The outlet of the desorption and regeneration zone I is connected to the inlet of the acid enrichment zone II, and the outlet of the acid enrichment zone II and the outlet of the first resin column in the adsorption and separation zone III are connected in parallel to the inlet of the second resin column; A feed inlet is provided at the entrance of the adsorption separation zone III, i.e., the entrance of the first resin, and an eluent inlet is provided at the entrance of the desorption and regeneration zone I; a first liquid outlet is provided at the outlet of the adsorption and separation zone III for recovering sugar, and a second liquid outlet is provided at the outlet of the desorption and regeneration zone I for recovering acid; The three-zone simulated moving bed is used for separating sugar and acid in the lignocellulose hydrolysis sugar solution containing inorganic acid.

2. The three-zone simulated moving bed according to claim 1, characterized in that: The simulated moving bed also includes an intermediate material storage tank. The outlet of the acid enrichment zone II and the outlet of the first resin column are connected in parallel to the intermediate material storage tank, and the intermediate material storage tank is connected in series with the second resin column.

3. The three-zone simulated moving bed according to claim 1, characterized in that: The H-type cation exchange resin has a basic skeleton of styrene-divinylbenzene copolymer, a functional group of sulfonic acid, a cross-linking degree of 2-10%, a spherical shape, and a particle size of 0.42-1.2 mm. + Concentration is 4-5.6meq / dry gm, humidity is 0.5-5%; And / or, the total sugar concentration in the inorganic acid-containing lignocellulose hydrolyzed sugar solution is 10-200 g / L; and / or, the concentration of inorganic acid in the inorganic acid-containing lignocellulose hydrolyzed sugar solution is 5-100 g / L.

4. Use of the three-zone simulated moving bed according to any one of claims 1 to 3 for separating sugars and acids from a lignocellulose hydrolyzed sugar solution containing an inorganic acid, characterized in that: The resin columns in the three-zone simulated moving bed are switched in sequence from the adsorption separation zone III to the acid enrichment zone II and then to the desorption regeneration zone I.

5. The use according to claim 4, characterized in that The steps include: S1: The lignocellulose hydrolyzed sugar solution containing inorganic acid is loaded from the inlet of the adsorption separation zone III, and at the same time, the eluent is loaded from the inlet of the desorption regeneration zone I; S2: The lignocellulose hydrolyzed sugar solution containing inorganic acid enters the adsorption separation zone III for adsorption separation, the resin column adsorbs the acid to separate the sugar, and the effluent at the outlet of the adsorption separation zone III, i.e., the sugar-rich liquid, is collected; After the resin column in the adsorption separation zone III is saturated with acid, it is moved out of the adsorption separation zone III and enters the acid enrichment zone II to enrich the inorganic acid and remove the residual sugar. The effluent obtained after the first resin column enters the acid enrichment zone II is an effluent containing sugar and acid. The effluent flows into the intermediate material storage tank, and the liquid in the intermediate material storage tank is pumped into the second resin column to repeat the adsorption separation; The resin column in the acid enrichment zone II enters the desorption regeneration zone I, where the eluent is eluted to remove the acid, and the effluent from the desorption regeneration zone I is collected, i.e., the acid-rich feed solution; Repeat S2 to perform a cyclic operation.

6. The use according to claim 5, characterized in that The eluent is water.

7. The use according to claim 5, characterized in that The first rate of loading the inorganic acid-containing lignocellulose hydrolyzed sugar solution is 1.2-12 BV / h; and / or, the second rate of elution with the eluent is 5-40 BV / h.

8. The use according to claim 5, characterized in that The third rate at which the liquid in the intermediate material storage tank enters the second resin column is 2.4-35 BV / h.

9. The use according to claim 5, characterized in that The fourth rate of the acid-rich liquid entering the acid enrichment zone II is 2.4-30 BV / h, and the fourth rate is controlled to be equal to the third rate - the first rate; the second rate is greater than the fourth rate.

10. The use according to claim 5, characterized in that The switching time of the resin column is 5-40 minutes.

Images