CN110862298A

CN110862298A - Preparation method of sorbitol

Info

Publication number: CN110862298A
Application number: CN201911085282.9A
Authority: CN
Inventors: 于丽丽; 徐云; 唐吉瑜; 张占锋; 陈召峰; 王勇; 胡航娜
Original assignee: Heilongjiang New And Adult Biotechnology Co Ltd; Zhejiang University ZJU; Zhejiang NHU Co Ltd
Current assignee: Heilongjiang New And Adult Biotechnology Co Ltd; Zhejiang University ZJU; Zhejiang NHU Co Ltd
Priority date: 2019-11-08
Filing date: 2019-11-08
Publication date: 2020-03-06
Anticipated expiration: 2039-11-08
Also published as: CN110862298B

Abstract

The invention relates to a preparation method of sorbitol, which comprises the steps of pre-adjusting the pH value of a glucose aqueous solution, putting the glucose aqueous solution into a reaction kettle for reaction, slowly pumping an alkali solution in the reaction process, reducing the loss of Ni below 20mg/L, and simultaneously reducing the sorbitol content above 97.0 percent.

Description

Preparation method of sorbitol

Technical Field

The invention belongs to the field of chemical synthesis, and particularly relates to a preparation method of sorbitol.

Background

Sorbitol is an important intermediate for synthesizing vitamin C, and is widely applied to the fields of food, tanning, daily cosmetics, paper making, detergents, toothpaste additives and the like. At present, a glucose catalytic hydrogenation process is generally adopted for preparing sorbitol in industry at home and abroad, and the production process mainly comprises the steps of preparation of a glucose solution, hydrogenation reaction, catalyst separation, ion exchange, solution evaporation, crystallization, drying and the like, wherein the hydrogenation reaction is a core technology.

Glucose solution with mass concentration of about 50% and hydrogen are mixed in a high-pressure reaction kettle, and the reaction temperature and pressure are well controlled under the catalytic action of a catalyst to produce sorbitol solution meeting the standard, so that the catalyst is the key in the whole process. The catalyst for preparing sorbitol by catalyzing glucose hydrogenation mainly comprises a Ru-based catalyst and a nickel-based catalyst, and Ru/C and Raney-Ni catalysts are more applied and researched.

At present, Raney-Ni catalysts are mainly used in China.

Raney-Ni catalyst is a metal Ni-Al alloy catalyst with a spongy pore structure, and has become the most commonly used catalyst in sorbitol production due to the advantages of low price, easily obtained raw materials and the like. The by-product gluconic acid formed in the hydrogenation process easily causes a great loss of Ni and Al, thereby causing the performance reduction of the catalyst. Ni is easily dissolved in sorbitol to cause loss, so that the activity is reduced, the quality of sorbitol is influenced, and the separation cost is increased.

According to the production index requirements of main downstream products of sorbitol, such as VC, solid sorbitol and the like, the Ni content in the sorbitol solution should be controlled. The existing technology for producing sorbitol by Raney Ni catalytic hydrogenation adopts the measure of adjusting the Ni loss in sorbitol solution by adding a large amount of alkali (I)General m_NaOH:m_Glucose>0.5%, pH much higher than 11), however, this method has a great influence on the yield of the product, and the amount of Ni loss is not so good.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a preparation method of sorbitol, which comprises the following steps:

1) mixing glucose and water, and heating to dissolve to obtain a glucose solution;

2) cooling the glucose solution obtained in the step 1), and adding an alkali solution to adjust the pH value to 8-11;

3) adding a nickel catalyst and the glucose solution obtained in the step 2) into a reaction container, performing air evacuation by using hydrogen and nitrogen, starting heating to perform a hydrogenation reaction, pumping an alkali solution in the process of temperature rise, and maintaining the pH value at 8-11;

4) after the reaction is finished, filtering the catalyst to finish the hydrogenation reaction to obtain a sorbitol product.

The pH values of the steps 2) and 3) are preferably 8-10.5. Experiments have shown that when the pH is greater than 11, the purity of the resulting sorbitol product is reduced.

In the above method for producing sorbitol, the ratio of glucose: the mass ratio of the water is 1: 0.5-2, preferably 1: 1.

In the above-mentioned process for the preparation of sorbitol, in step 2), a phosphate, for example NaH, may be added simultaneously with the adjustment of the pH₂PO₄The glucose solution is cooled to room temperature and NaH is added₂PO₄Preferably NaH₂PO₄·12H₂O solid, wherein the solid accounts for 0.3-1% of the mass of the glucose. By multiple sets of experimental data (e.g., analogs including Na)₂HPO₄) In contrast, the substance can suppress the loss of Al element.

In the step 3) of the preparation method of the sorbitol, when the temperature rises to 90-120 ℃, pumping the alkali solution.

In the preparation method of the sorbitol, the alkali solution is 0.1-2.0 mol/L NaOH and Na₂CO₃、NaHCO₃And aqueous KOH solution.

The alkali solution is 0.1-2.0 mol/L NaOH aqueous solution. The pH value of the NaOH aqueous solution is quickly and conveniently adjusted, and the cost is economical.

The nickel catalyst comprises Raney Ni catalyst or Mo modified Raney nickel. The preparation method is suitable for the common Raney nickel catalyst.

The amount of the nickel catalyst is 10-30% of the mass of the glucose. When the amount of the nickel catalyst is too high, the weight of the catalyst is too large, the stirring effect is poor, the selectivity of the catalyst is obviously reduced, and when the amount of the nickel catalyst is too low, the activity of the catalyst is poor, the reaction time is long and the stability is poor.

In the step 3), the pumping speed of the alkali solution is 0.5-5.00 ml/min, the pumping speed is too high to inhibit Ni loss, if the pumping speed is too low, the pumping time is too long to increase energy consumption, and the pumping standard of the alkali solution is to effectively inhibit the loss of Ni and keep the yield of sorbitol at a higher level (about 97-98%).

The loss amount of Ni metal in the reaction solution after hydrogenation reaction is determined to be 5-20 mg/L through ICP (inductively coupled plasma), and the content of sorbitol in the product is determined to be 97.0-98.5% through liquid chromatography.

The method can control the loss of Ni and simultaneously reduce the influence on the sorbitol content to a very low degree, so that the sorbitol content and the loss of Ni can be well controlled within the index range required by industrial production

Compared with the prior art, the invention has the following advantages:

1. the method controls the loss of Ni by adjusting the initial pH value of the reaction liquid and adopting a mode of continuously dropwise adding alkali liquor (dropwise adding flow rate) in the reaction process, has the advantages of simple process, simple and convenient operation, good effect of inhibiting the loss of Ni, environmental friendliness and stable yield at a high level of 97.0-98.5%.

2. The NaOH adopted by the invention has low price and good economy, is environment-friendly and meets the requirement of green chemistry.

Detailed Description

The following experimental examples are intended to further illustrate the invention but not to limit it. All the technologies realized based on the above contents of the present invention belong to the scope of the present invention.

Example 1

Raney Ni catalyst

Example 1

(1) Preparing an alkali solution: NaOH solution with the concentration of 1.0mol/L is prepared.

(2) Adjusting the initial pH value of the glucose solution: according to m_Glucose:m_{Water (W)}Heating glucose at a certain temperature to completely dissolve to form an aqueous solution, cooling to room temperature, and adding NaH accounting for 0.9% of the mass of glucose₂PO₄·12H₂And adjusting the pH value of the glucose solution to 9 by using the prepared alkali solution.

(3) Batch hydrogenation reaction: the glucose solution with the adjusted pH value and Raney Ni catalyst (20 percent of the mass of glucose) are poured into a 1L high-pressure reaction kettle, and hydrogen is introduced to start hydrogenation reaction after nitrogen and hydrogen are respectively used for evacuation three times. The temperature was observed during the process, and when the reaction temperature reached 120 ℃, the high pressure pump was turned on to start pumping the alkali solution at a flow rate of 0.5mL/min and a volume of about 2.5mL was pumped in 5 min. Closing the high-pressure pump after the reaction is finished, and continuing to react until the pressure is not obviously changed; and filtering out the catalyst, and then sampling to be tested.

(4) The loss of Ni metal in the reaction solution after the hydrogenation reaction was measured by ICP was 15.44mg/L, and the sorbitol content in the product was measured by liquid chromatography to be 97.75%.

Examples 2-10 the procedure was the same as in example 1, and the specific data are shown in Table 1:

TABLE 1 Raney Ni examples

Comparative example 1: initial adjustment and no dripping in the middle

(1) Preparing an alkali solution: NaOH with the concentration of 1.0mol/L is prepared.

(2) Adjusting the initial pH value of the glucose solution: according to m_Glucose:m_{Water (W)}Heating glucose at a certain temperature to completely dissolve to form an aqueous solution, cooling to room temperature, and adding NaH accounting for 0.9% of the mass of glucose₂PO₄·12H₂O and 5ml of 1.0mol/L (excess lye) of the above prepared alkali solution.

(3) Batch hydrogenation reaction: the glucose solution with the adjusted pH value and Raney Ni catalyst (20 percent of the mass of glucose) are poured into a 1L high-pressure reaction kettle, and hydrogen is introduced to start hydrogenation reaction after nitrogen and hydrogen are respectively used for evacuation three times. Stopping the reaction until the pressure does not change obviously; and filtering out the catalyst, and then sampling to be tested.

(4) The loss of Ni metal in the reaction solution after the hydrogenation reaction was measured by ICP was 8.42mg/L, and the sorbitol content in the product was measured by liquid chromatography at 93.07%.

Comparative example 2: initially unregulated and intermediately added

(1) Preparing an alkali solution: NaOH with the concentration of 1.0mol/L is prepared respectively.

(2) Adjusting the initial pH value of the glucose solution: according to m_Glucose:m_{Water (W)}Glucose was heated to complete dissolution at a temperature to a ratio of 1:1 to form an aqueous solution, which was cooled to room temperature.

(3) Batch hydrogenation reaction: the glucose solution and Raney Ni catalyst (20% of glucose mass) are poured into a 1L high-pressure reaction kettle, and hydrogen is introduced to start hydrogenation reaction after nitrogen and hydrogen are respectively used for evacuation three times. The temperature was observed during the process, when the reaction temperature reached 120 ℃, the high pressure pump was turned on to start pumping NaOH alkali solution at a flow rate of 0.5mL/min and a volume of 5mL pumped over 10 min. Closing the high-pressure pump after the reaction is finished, and continuing to react until the pressure is not obviously changed; and filtering out the catalyst, and then sampling to be tested.

(4) The loss of Ni metal in the reaction solution after the hydrogenation reaction was measured by ICP was 25.36mg/L, and the sorbitol content in the product was measured by liquid chromatography to be 92.33%.

Comparative example summary

In comparative examples 1-2, it was found that if excessive alkali solution is directly added, no alkali solution is added dropwise in the middle, the loss of Ni is reduced, but the sorbitol content is significantly reduced to 93.07%. If the pH value is not adjusted initially, 5ml of alkali liquor is dripped in the middle, the loss of Ni is high, and the content of sorbitol is low, namely 92.33%. Are not in accordance with the preparation requirement of the sorbierite.

Examples 11 to 14

Mo modified Raney Ni catalyst, see table 2.

TABLE 2 specific examples of Mo modified Raney Ni

Examples 11-14 show that when using Mo modified Raney Ni catalyst for sorbitol production, the preparation method can still control the Ni loss amount to be below 20mg/l, even below 15mg/l, and the sorbitol content is maintained between 97% and 99%, thus meeting the requirements of the current high-purity sorbitol industrial production.

Claims

1. The preparation method of the sorbitol is characterized by comprising the following steps:

2. The method for preparing sorbitol according to claim 1, wherein the ratio of glucose: the mass ratio of water is 1:0.5 to 2.

3. The method for preparing sorbitol according to claim 2, wherein the ratio of glucose: the mass ratio of water is 1: 1.

4. the method for preparing sorbitol according to claim 1, wherein the pH value of the steps 2) and 3) is preferably 8 to 10.5.

5. The method for preparing sorbitol according to claim 1, wherein in step 3), when the temperature is raised to 90-120 ℃, an alkali solution is pumped in.

6. The method for producing sorbitol according to claim 1, wherein the alkali solution is 0.1 to 2.0mol/L NaOH or Na₂CO₃、NaHCO₃And aqueous KOH solution.

7. The method of claim 6, wherein the alkali solution is 0.1 to 2.0mol/L NaOH aqueous solution.

8. The method for preparing sorbitol according to claim 1, wherein the nickel catalyst comprises Raney Ni catalyst or Mo-modified Raney nickel.

9. The method for producing sorbitol according to claim 1, wherein the amount of the nickel catalyst is 10 to 30% by mass of glucose.

10. The method for preparing sorbitol according to claim 1, wherein NaH is added to the mixture during the step 2) while adjusting the pH by adding the alkali solution₂PO₄Or NaH₂PO4 hydrate, added in a proportion of NaH₂PO₄·12H₂The solid mass of O is calculated to be 0.3-1% of the mass of glucose.