A bleaching and decolorizing device and decolorizing method for alkyl polyglycoside

Abstract

A bleaching and decolorizing device and decolorizing method for alkyl glycosides, belonging to the technical field of post-processing bleaching and decolorizing of alkyl glycosides. It includes a reactor, a crude alkyl glycoside storage tank, an alkyl glycoside receiving tank, and a hydrogen peroxide storage tank. The crude alkyl glycoside storage tank is connected to the feed port of the reactor through a metering pump and a first control valve connected in series, and the discharge port of the reactor is connected to a second control valve, and the outlet end of the second control valve is connected to a circulation pump through a first pipeline, and the outlet end of the circulation pump is connected to the reactor through a second pipeline; the alkyl glycoside receiving tank is connected to the first pipeline through a third control valve and a feed pump connected in series, and the hydrogen peroxide storage tank is connected to the first pipeline through a flow meter and a fourth control valve connected in series. The present invention is provided with a strong self-priming multiphase flow pump, and hydrogen peroxide is pumped into the reactor through the strong self-priming multiphase flow pump, so that the entire system forms a circulation system, which can reduce the amount of hydrogen peroxide used, reduce the amount of foam generated instantly, and shorten the time waiting for the foam to be eliminated.

Description

Technical Field

[0001] The invention belongs to the technical field of post-processing bleaching and decolorization of alkyl glycosides, and particularly relates to a bleaching and decolorization device for alkyl glycosides. Background Art

[0002] Alkyl polyglycoside is a mild nonionic surfactant, which is produced by the dehydration of natural renewable resources fatty alcohol and glucose under acidic catalyst. It has good biodegradability, is beneficial to environmental protection, and is internationally recognized as the first choice of "green" functional surfactant. It has many advantages such as rich and delicate foam, good foam stability, strong compatibility, obvious synergistic effect, strong broad-spectrum antibacterial activity, strong alkali resistance and salt resistance. Therefore, this surfactant shows strong vitality whether from the perspective of resources, environmental protection or consumer psychology. It conforms to the requirements of green and environmental protection and is increasingly valued by people. With the strengthening of people's environmental awareness and the improvement of APG product quality, APG has been widely used in shampoo, shower gel, facial cleanser and other personal care products and dishwashing detergent and laundry detergent and other household detergent products in addition to its application in pesticide emulsifiers and textile printing and dyeing auxiliaries. It has been exported to Europe, America and Southeast Asia. Color is one of the important quality indicators for measuring surfactants. Better color and appearance can expand the application range of APG products, especially as raw materials for personal care products. Light and transparent appearance will certainly increase its commodity value. Moreover, as the color deepens, the quality will decrease, and even accompanied by a bad smell, which will greatly affect the performance of the product. If this product is used to formulate products that come into direct contact with the human body, such as cosmetics, it may even cause certain irritation to human skin. Surfactants with low color have good quality, are safe for the human body, and have little harm.

[0003] There are two main methods for industrial production of alkyl glycosides. One is the "two-step method" used in the early days, also known as the "transglycosylation method or acetal exchange method", that is, glucose is first reacted with a lower alcohol, and then an acetal exchange reaction is carried out with a higher alcohol to obtain a higher glycoside, and finally an alkyl glycoside aqueous solution is obtained through distillation, bleaching and other processes. Although the production process of this method is easy to control, the quality of the APG product obtained is poor (especially the product contains more strong irritating odor), and the alkyl glycoside obtained has problems such as dark color, high residual alcohol content, and long reaction time. The final product is mostly mixed glycoside, which is not conducive to the preparation of derivatives in the subsequent process, affecting the quality of the final product, and the HLB value of the product is not easy to control, so this method is gradually eliminated. Another method for producing alkyl glycosides is the "one-step method", also known as direct glycosidation, which is to allow glucose to directly react with higher alcohols (usually C8-C20 alcohols for the preparation of alkyl glycosides) in a solid / liquid phase under a certain temperature, pressure and in the presence of an acidic catalyst. The reaction principle is the acetalization process of the hemiacetal hydroxyl group on the glucose ring with the hydroxyl group of the fatty alcohol, i.e., glycosidation reaction, and then the alkyl glycoside product is obtained after neutralization, distillation, dealcoholization, refining and bleaching. This method is the current mainstream method.

[0004] However, regardless of whether it is a two-step production process or a one-step production process, the alkyl glycosides after dealcoholization generally have a heavy color because the glucose and heat-sensitive substances such as glycosides therein are carbonized due to long-term heating. Moreover, in the process of producing alkyl glycosides by the one-step method, since glucose is insoluble in higher fatty alcohols, a solid-liquid two-phase is formed and sugar easily forms agglomerates, aggregates, settles and accumulates at the bottom of the reactor and is carbonized, causing the product color to deepen. Therefore, further refining treatment is required - dealcoholization and decolorization before it can be shipped out of the factory.

[0005] The dealcoholization and decolorization processes have always been the focus of research at home and abroad. Due to the physical and chemical characteristics of alkyl polyglycosides, how to reduce the content of free alcohol in the product after the reaction to less than 1% has always been an operational difficulty in the industry. At present, the industry mostly uses a two-stage series evaporation device. Generally, the first stage is a falling film evaporator, on which most of the fatty alcohol can be removed, and then a film evaporator with a scraper or a short-path evaporator is used as the second stage to remove the remaining fatty alcohol. Some manufacturers also add an evaporator on this basis and use a three-stage evaporation device.

[0006] In recent years, some people have proposed new dealcoholization methods to address the problem of darkening the color of alkyl polyglycosides caused by high-temperature dealcoholization, such as solvent extraction, adsorption desorption, supercritical fluid extraction, and silica adsorption. Lan Renhua from South China University of Technology compared solvent extraction and vacuum distillation. The results showed that using ether as an extractant can reduce the residual alcohol content in the product to 0.9%, and effectively reduce the purification and separation time, and obtain colorless and high-purity alkyl polyglycoside samples. However, from an industrial perspective, these methods are not suitable for industrial production. After the free fatty alcohol is removed, the color of the product is still very dark and cannot meet the needs of customers in the market. Therefore, the product needs to be decolorized. The commonly used decolorization methods are physical decolorization and chemical decolorization.

[0007] Physical decolorization mainly relies on adsorbents to adsorb the coloring substances in alkyl glycosides. The adsorbents used include activated carbon, bentonite, diatomaceous earth, zeolite and macroporous resin. Activated carbon is the most commonly used adsorption decolorizer, which not only has the function of decolorization, but also has the function of removing odor. Physical decolorization can achieve the decolorization function, but the decolorization effect is limited, and there is a problem of adsorption loss of the target product during the decolorization process.

[0008] Chemical decolorization mainly uses decolorizers to destroy the color-developing groups in alkyl glycosides, including oxidation decolorization, reduction decolorization and photodecolorization. Reduction decolorization is to remove the components that become colorants in the distillation process in advance, thereby avoiding the deepening of the product color; the biggest advantage of using photodecolorization is that no impurities are introduced into the product, but these two decolorization technologies are still not very mature. At present, the more mature decolorization process is oxidation decolorization, and the commonly used decolorizers are hypochlorite, chlorine dioxide, hydrogen peroxide, ozone, peroxy acid, sodium dithionite, sodium borohydride and sodium bisulfite. Japanese patent JP91-71481 introduces that when sugar alcohols react, ultraviolet irradiation has a certain decolorization effect. German patent DE3940827 introduces that using 100-1000W mercury lamps to irradiate glycoside aqueous solutions also achieved good results.

[0009] In the process of preparing alkyl glycosides, problems often occur due to improper control of reaction conditions, such as decomposition and carbonization, and the raw material glucose used is a heat and acid sensitive substance, which leads to a darker color of the product, a lower quality, and even a bad smell, which greatly affects the performance of the product. Therefore, bleaching and decolorization are essential processes. In order to improve the color, in addition to improving the process conditions, hydrogen peroxide is often used as a bleaching agent. Decolorization with hydrogen peroxide does not produce by-products and is pollution-free, making it an ideal bleaching agent.

[0010] Bleaching principle: H2O2 generates hydroxyl anions in alkaline medium: H2O2+OH - →HOO -+H2O, using peroxide ions to destroy the conjugated macromolecular structure to make it lose its chromophore group, thus decolorizing the alkyl glycoside.

[0011] Under alkaline conditions, oxidation reaction is favorable, and the pH value is controlled to be 8~12. Experiments have proved that the lower the residual sugar content in the product, the lighter the color after bleaching; the lower the total solid content, the easier it is to bleach. When adding decolorizing aids when bleaching APG with hydrogen peroxide, not only the color of the product is light, but also the stability to heat and alkali is good. Zhang Jie of China Daily Chemical Industry Research Institute has done research on hydrogen peroxide bleaching alkyl polyglycosides. The results show that the use of tetraacetylethylenediamine to activate the hydrogen peroxide system can effectively reduce the color of alkyl polyglycosides. Sodium magnesium ethylenediaminetetraacetate also has a good bleaching effect. When it is used as a bleaching aid (addition amount is 0.3%~0.5%), the color stability of the bleaching liquid is good at room temperature and high temperature. After bleaching, the remaining hydrogen peroxide will cause the color and odor of the product to deteriorate during storage, and the pH will become acidic. Generally, reducing substances such as NaBH4 and MnO can be added to decompose the residual hydrogen peroxide to ensure the stability of the product storage. Manganese dioxide, platinum group elements, peroxidase, ascorbic acid and its salts are used to contact the hydrogen peroxide in the residual product to decompose it and reduce the content of hydrogen peroxide to a level that cannot be detected by iodine titration, thereby obtaining alkyl glycosides with very good odor and color storage stability. Alkaline earth metal ions (such as Mg) are added during the bleaching process. 2+ and Zn 2+ ) and alkali metal silicates, or adding hydrotalcite and triacetin as activators can improve the bleaching effect of hydrogen peroxide and the color stability of the bleached product.

[0012] The basis for measuring bleaching: the color of a substance means that the part of the light that is the complementary color of that color absorbs the most. The bleaching of a substance can be considered as removing or damaging the light-absorbing substance from the substance. According to the Kubelka-Munk theory, the light absorption coefficient decreases, while the light scattering coefficient changes very little. When measuring the effect of bleaching, the reduction in visible light absorption can be used to judge.

[0013] Patent CN201530788U discloses a decolorization and bleaching device for light-colored transparent alkyl glycoside, including a bleaching reactor cylinder, in which a spiral agitator is arranged, which changes the rotation and turning of materials in an ordinary bleaching reactor into up and down turning. However, when using this device, the bleaching agent and the alkyl glycoside are poorly mixed, and severe foaming occurs during the bleaching and decolorization process.

[0014] Patent JP91-71481 introduces that alkyl glycoside can be irradiated with ultraviolet light during the reaction process, which has a certain decolorization effect; Patent DE3940827 mentions that alkyl glycoside aqueous solution can be irradiated with a mercury lamp at 30°C to obtain a high-quality alkyl glycoside product, but these two decolorization technologies are immature and cannot be industrialized.

[0015] Patents CN1305886C, CN1077397A, and CN100390187C all use hydrogen peroxide to bleach the dealcoholized solution. However, this bleaching method has a low utilization rate of hydrogen peroxide due to the decomposition of hydrogen peroxide itself. At the same time, the aqueous solution of alkyl glycoside will produce stable foam, making the bleaching process difficult (hydrogen peroxide decomposes to produce oxygen, and oxygen emerges from the solution to form a large number of bubbles in the solution). In addition, there is excessive undecomposed hydrogen peroxide in the bleached product, resulting in color instability and the product is prone to yellowing during storage.

[0016] Patent US6166189 proposes to treat the bleached alkyl glycoside aqueous solution with lithium borohydride, sodium borohydride or potassium borohydride to remove excess hydrogen peroxide and stabilize the product. However, metal borohydrides are expensive and have high production costs, making them unsuitable for industrial production.

[0017] The bleaching and decolorization methods currently used are mainly intermittent kettle processes, which add hydrogen peroxide in batches, and are prone to the following problems: 1. The reaction process is carried out in the reactor, and a large amount of foam will be formed above the liquid surface of the reactor; 2. It is necessary to wait for the previous foam to disappear before adding the subsequent hydrogen peroxide, which consumes a lot of time; 3. The subsequent hydrogen peroxide is added from the top, which will be blocked by foam. In this process, due to the high temperature in the kettle, part of the hydrogen peroxide has decomposed before contacting the material, and more hydrogen peroxide is often required; 4. After the product is tested to see if bleaching is completed, if hydrogen peroxide is added again, the above problems will also occur; 5. The reaction process is relatively long, which will increase the instability of product quality; 6. There is a lot of excess hydrogen peroxide residue in the product, and removing it will increase costs. Summary of the invention

[0018] The object of the present invention is to overcome the shortcomings of the prior art and provide an alkyl glycoside bleaching and decolorizing device which has less foam generation, less hydrogen peroxide consumption, better decolorization effect, shorter bleaching time, simple operation, high efficiency, low cost and easy to realize automatic control compared with an intermittent kettle method.

[0019] The technical scheme for achieving the above object is: a bleaching and decolorizing device for alkyl glycoside, characterized in that it comprises a reactor, a crude alkyl glycoside storage tank, an alkyl glycoside receiving tank, and a hydrogen peroxide storage tank, wherein the crude alkyl glycoside storage tank is connected to the feed port of the reactor through a metering pump and a first control valve connected in series, the discharge port of the reactor is connected to a second control valve, the outlet end of the second control valve is connected to a circulation pump through a first pipeline, and the outlet end of the circulation pump is connected to the reactor through a second pipeline;

[0020] The alkyl glycoside receiving tank is connected to the first pipeline via a third control valve, and the hydrogen peroxide storage tank is connected to the first pipeline via a series-connected flow meter and a fourth control valve.

[0021] Furthermore, the circulation pump is a powerful self-priming multiphase flow pump.

[0022] Another object of the present invention is to provide a method for bleaching and decolorizing an alkyl glycoside, characterized in that it comprises the following steps:

[0023] 1) Open the first control valve, close the second, third and fourth control valves, start the metering pump, and transport a set amount of crude alkyl glycoside from the crude alkyl glycoside storage tank to the reactor, and then close the first control valve;

[0024] 2) Add magnesium sulfate and liquid alkali into the reactor, then heat the reactor to 75-80°C, and stir the crude alkyl glycoside, magnesium sulfate and liquid alkali in the reactor to obtain a mixed raw material;

[0025] 3) Open the second and fourth control valves, start the circulation pump, and keep the working temperature of the reactor at 75-80°C. Under the action of the circulation pump, the hydrogen peroxide in the hydrogen peroxide storage tank is output through the flow meter, and when the output reaches the set amount, close the fourth control valve, and the hydrogen peroxide output from the hydrogen peroxide storage tank and the mixed raw material output from the reactor are circulated and reacted for 14-17 hours through the first pipeline, the second pipeline, and the reactor in sequence to obtain the alkyl glycoside product;

[0026] 4) Close the circulation pump, open the third control valve, start the feed pump, and input the alkyl glycoside product obtained by the reaction into the alkyl glycoside receiving tank.

[0027] Furthermore, the mass ratio of magnesium sulfate to crude alkyl glycoside is 0.1-0.5:100, the mass ratio of liquid alkali to crude alkyl glycoside is 5-15:100, and the mass ratio of hydrogen peroxide to crude alkyl glycoside is 5-15:100.

[0028] Furthermore, the flow rate of the metering pump is 0 to 2000 kg / h, and the pressure is 0.1 to 1.0 MPa.

[0029] Furthermore, the flow rate of the flow meter is 0 to 250 kg / h, and the pressure is 0.1 to 1.0 MPa.

[0030] Furthermore, the crude alkyl glycoside is a dark alkyl glycoside aqueous solution with a concentration range of 50% to 80%.

[0031] Furthermore, the alkyl glycoside used is a C8-14 alkyl glycoside.

[0032] The present invention is provided with a powerful self-priming multiphase flow pump, through which hydrogen peroxide is pumped into the kettle, so that the entire system forms a circulation system, so that the addition of hydrogen peroxide can become controllable and sustainable, the amount of hydrogen peroxide used can be reduced, the amount of foam generated instantly can be reduced, and the time for waiting for the foam to disappear can be shortened.

[0033] The process of bleaching hydrogen peroxide with materials is cyclic, and the hydrogen peroxide begins to be initially mixed with the materials in the pipeline, and the two are soluble. Even if there is a barrier of foam, the hydrogen peroxide still bleaches the materials. In this process, the loss of hydrogen peroxide can be reduced to a minimum. At the same time, because of the circulation system, the liquid flows up and down, which can shorten the time for eliminating foam in the kettle; the shortening of the reaction time reduces the instability of the product and improves the quality of the product.

[0034] In short, compared with the prior art, the present invention can solve a series of problems caused by the foam generated by bleaching. Because the addition of hydrogen peroxide is controllable and sustainable, the operation is simple, the labor is reduced, and it is easy to control automatically; because the bleaching process has a strong self-priming multiphase flow pump, it becomes a recyclable system, so the bleaching efficiency of hydrogen peroxide is increased, the loss is reduced, the amount of hydrogen peroxide used is reduced, and the reaction time is shortened. At the same time, the production efficiency is also improved, the cost is reduced, and the quality of the product is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The system principle diagram of the bleaching and decolorizing device of the alkyl glycoside of the present invention. DETAILED DESCRIPTION

[0036] In order to facilitate the understanding of the present invention, the following Figure 1 The present invention is further described through specific implementation methods; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and the protection scope of the present invention is not limited to this; based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0037] like Figure 1 As shown, the present invention discloses a bleaching and decolorizing device for alkyl glycoside, comprising a reactor 1, an alkyl glycoside crude product storage tank 4, an alkyl glycoside receiving tank 3, and a hydrogen peroxide storage tank 2. The alkyl glycoside crude product storage tank 4 is connected to the feed port of the reactor 1 through a metering pump 10 and a first control valve 6 connected in series. The flow rate of the metering pump is 0-2000 kg / h and the pressure is 0.1-1.0 MPa. The discharge port of the reactor 1 is connected to a second control valve 9. The outlet end of the second control valve 9 is connected to a circulation pump 5 through a first pipeline 13. The circulation pump 5 is a strong self-priming multiphase flow pump. The outlet end of the circulation pump 5 is connected to the reactor 1 through a second pipeline 14.

[0038] The alkyl glycoside receiving tank 2 is connected to the first pipeline 13 through the third control valve 7 and the feed pump 15 connected in series, and the hydrogen peroxide storage tank 3 is connected to the first pipeline 13 through the flow meter 11 and the fourth control valve 8 connected in series. The flow meter has a flow rate of 0 to 250 kg / h and a pressure of 0.1 to 1.0 MPa.

[0039] In order to achieve a good heat preservation effect during the reaction process, the first pipeline 13 and the second pipeline 14 are wrapped with a heat preservation layer.

[0040] The present invention also discloses a bleaching and decolorizing method of the bleaching and decolorizing device, comprising the following steps:

[0041] 1) Open the first control valve 6, close the second control valve 9, the third control valve 7, and the fourth control valve 8, start the metering pump 10, and transport a set amount of crude alkyl glycoside from the crude alkyl glycoside storage tank 4 to the reactor 1, and then close the first control valve 6;

[0042] 2) adding magnesium sulfate and liquid alkali (a sodium hydroxide aqueous solution with a concentration of 30-35%) into the reactor 1, then heating the reactor 1 to 75-80° C., and at the same time, stirring the crude alkyl glycoside, magnesium sulfate and liquid alkali in the reactor 1 to obtain a mixed raw material;

[0043] The mass ratio of magnesium sulfate to crude alkyl glycoside is 0.1-0.5:100, and the mass ratio of liquid alkali to crude alkyl glycoside is 5-15:100.

[0044] 3) Open the second control valve 9 and the fourth control valve 8, start the circulation pump 5, and keep the working temperature of the reactor 1 at 75-80°C. Under the action of the circulation pump 5, the hydrogen peroxide (with a concentration of 25%-35%) in the hydrogen peroxide storage tank 2 is output through the flow meter 11, and when the output reaches the set amount, close the fourth control valve 8, and the hydrogen peroxide output from the hydrogen peroxide storage tank 3 and the mixed raw material output from the reactor 1 are circulated and reacted for 14-17 hours in sequence through the first pipeline 13, the second pipeline 14, and the reactor 1 to obtain the alkyl glycoside product;

[0045] Wherein, the mass ratio of hydrogen peroxide to crude alkyl glycoside is 5-15:100.

[0046] 4) Close the circulation pump 5, open the third control valve 7, start the feed pump 15, and input the alkyl glycoside product obtained by the reaction into the alkyl glycoside receiving tank 2.

[0047] Example 1

[0048] The crude alkyl glycoside concentration used in this example is 50% C8-10 alkyl glycoside aqueous solution, and the specific steps are as follows:

[0049] 1) Open the first control valve 6, close the second control valve 9, the third control valve 7, and the fourth control valve 8, start the metering pump 10, and transport 5000 kg of crude alkyl glycoside from the crude alkyl glycoside storage tank 4 to the reactor 1, and then close the first control valve 6;

[0050] 2) Add 5 kg of magnesium sulfate and 250 kg of liquid caustic soda with a concentration of 30% into the reactor 1, then heat the reactor 1 to 75° C., and at the same time, stir the crude alkyl glycoside, magnesium sulfate and liquid caustic soda in the reactor 1 to obtain a mixed raw material;

[0051] 3) Open the second control valve 9 and the fourth control valve 8, while keeping the working temperature of the reactor 1 at 75°C, start the circulation pump 5, and the hydrogen peroxide storage tank 2 outputs 250 kg of hydrogen peroxide (with a concentration of 25%) through the flow meter 11, then close the fourth control valve 8, and the hydrogen peroxide output from the hydrogen peroxide storage tank 2 and the mixed raw material output from the reactor 1 are circulated and reacted for 14 hours through the first pipeline 13, the second pipeline 14, and the reactor 1 in sequence to obtain a light-colored to colorless alkyl glycoside product;

[0052] 4) Close the circulation pump 5, open the third control valve 7, start the feed pump 15, and input the alkyl glycoside product obtained by the reaction into the alkyl glycoside receiving tank 2.

[0053] Example 2

[0054] The crude alkyl glycoside concentration used in this example is 60% C8-10 alkyl glycoside aqueous solution, and the specific steps are as follows:

[0055] 1) Open the first control valve 6, start the metering pump 10, and transport 6000 kg of crude alkyl glycoside from the crude alkyl glycoside storage tank 4 to the reactor 1;

[0056] 2) Add 6 kg of magnesium sulfate and 300 kg of liquid caustic soda with a concentration of 35% into the reactor 1, then heat the reactor to 80° C. and stir the crude alkyl glycoside, magnesium sulfate and liquid caustic soda in the reactor to obtain a mixed raw material;

[0057] 3) Open the second control valve 9 and the fourth control valve 8, while keeping the working temperature of the reactor 1 at 80°C, start the circulation pump 5, and the hydrogen peroxide storage tank 2 outputs 360 kg of hydrogen peroxide (with a concentration of 35%) through the flow meter 11, close the fourth control valve 8, and the hydrogen peroxide output from the hydrogen peroxide storage tank 2 and the mixed raw material output from the reactor 1 are circulated and reacted for 16 hours through the first pipeline 13, the second pipeline 14, and the reactor 1 in sequence to obtain a light-colored to colorless alkyl glycoside product;

[0058] 4) Close the circulation pump 5, open the third control valve 7, start the feed pump 15, and input the alkyl glycoside product obtained by the reaction into the alkyl glycoside receiving tank 2.

[0059] Example 3

[0060] The crude alkyl glycoside concentration used in this example is 50% C12-14 alkyl glycoside aqueous solution, and the specific steps are as follows:

[0061] 1) Open the first control valve 6, start the metering pump 10, and transport 5000 kg of crude alkyl glycoside from the crude alkyl glycoside storage tank 4 to the reactor 1;

[0062] 2) Add 25 kg of magnesium sulfate and 450 kg of liquid caustic soda with a concentration of 35% into the reactor 1, then heat the reactor to 75° C. and stir the crude alkyl glycoside, magnesium sulfate and liquid caustic soda in the reactor to obtain a mixed raw material;

[0063] 3) Open the second control valve 9 and the fourth control valve 8, start the circulation pump 5, the hydrogen peroxide storage tank 2 outputs 500 kg of hydrogen peroxide through the flow meter 11, close the fourth control valve 8, the hydrogen peroxide output from the hydrogen peroxide storage tank 2 and the mixed raw material output from the reactor 1 are circulated and reacted for 17 hours through the first pipeline 13, the second pipeline 14, and the reactor 1 in sequence to obtain a light-colored to colorless alkyl glycoside product;

[0064] 4) Close the circulation pump 5, open the third control valve 7, start the feed pump 15, and input the alkyl glycoside product obtained by the reaction into the alkyl glycoside receiving tank 2.

[0065] Example 4

[0066] The crude alkyl glycoside concentration used in this embodiment is 80% of a C12-14 alkyl glycoside aqueous solution, and the specific steps are as follows:

[0067] 1) Open the first control valve 6, start the metering pump 10, and transport 5000 kg of crude alkyl glycoside from the crude alkyl glycoside storage tank 4 to the reactor 1;

[0068] 2) Add 25 kg of magnesium sulfate and 750 kg of liquid caustic soda with a concentration of 35% into the reactor 1, then heat the reactor to 75° C. and stir the crude alkyl glycoside, magnesium sulfate and liquid caustic soda in the reactor to obtain a mixed raw material;

[0069] 3) Open the second control valve 9 and the fourth control valve 8, start the circulation pump 5, the hydrogen peroxide storage tank 2 outputs 750 kg of hydrogen peroxide through the flow meter 11, close the fourth control valve 8, and the hydrogen peroxide output from the hydrogen peroxide storage tank 2 and the mixed raw material output from the reactor 1 are circulated and reacted for 17 hours through the first pipeline 13, the second pipeline 14, and the reactor 1 in sequence to obtain a light-colored to colorless alkyl glycoside product;

[0070] 4) Close the circulation pump 5, open the third control valve 7, start the feed pump 15, and input the alkyl glycoside product obtained by the reaction into the alkyl glycoside receiving tank 2.

[0071] Comparative Example (using intermittent kettle reaction device)

[0072] The crude alkyl glycoside concentration used in this example is 50% C8-10 alkyl glycoside aqueous solution, and the specific steps are as follows:

[0073] 1) 5000 kg of crude alkyl glycoside is transported from the crude alkyl glycoside storage tank to the reactor by a metering pump;

[0074] 2) Add 5kg of magnesium sulfate and 250kg of 35% liquid caustic soda into the reactor, and then heat the reactor to 75°C. During this heating process, the raw materials, magnesium sulfate and liquid caustic soda are evenly mixed;

[0075] 3) After mixing evenly, 360 kg of hydrogen peroxide was added to the reactor in batches, and the reaction was carried out at a temperature of 75-85°C for 26 hours to obtain a light-colored to colorless alkyl glycoside product;

[0076] By comparing Examples 1, 2, 3, and 4 with the comparative examples, it can be seen that the amount of hydrogen peroxide used for bleaching the same crude glycoside material and the reaction time are much less in Example 1 of the present invention than in the comparative example using the prior art, and the other relatively embodiments are also less than the production using the prior art. It can be seen from this that the present invention does provide a bleaching and decolorizing device and decolorizing method for alkyl glycosides that produces less foam than the intermittent kettle method, uses less hydrogen peroxide, has a good decolorizing effect, has a short bleaching time, is simple to operate, has a high efficiency, is low in cost, and is easy to realize automatic control.

[0077] In addition, because the process of bleaching the hydrogen peroxide and the material in the present invention is circulated, the purpose of defoaming can be achieved during the circulation process. Therefore, the amount of foam in the alkyl polyglycoside products obtained in Examples 1, 2, 3, and 4 is much smaller than the amount of foam in the comparative example product.

Claims

1. A bleaching and decolorizing device for alkyl glycosides, characterized in that: It includes a reactor, an alkyl glycoside crude product storage tank, an alkyl glycoside receiving tank, and a hydrogen peroxide storage tank. The alkyl glycoside crude product storage tank is connected to the feed port of the reactor through a metering pump and a first control valve connected in series. The discharge port of the reactor is connected to a second control valve. The outlet end of the second control valve is connected to a circulation pump through a first pipeline. The outlet end of the circulation pump is connected to the reactor through a second pipeline. The circulation pump is a strong self-priming multiphase flow pump. The alkyl polyglycoside receiving tank is connected to the first pipeline through a third control valve and a feed pump connected in series, and the hydrogen peroxide storage tank is connected to the first pipeline through a flow meter and a fourth control valve connected in series.

2. A method for bleaching and decolorizing an alkyl glycoside, characterized in that: The steps include: 1) Open the first control valve, close the second, third and fourth control valves, start the metering pump, and transport a set amount of crude alkyl glycoside from the crude alkyl glycoside storage tank to the reactor, and then close the first control valve; 2) adding magnesium sulfate and liquid alkali into the reactor, and then heating the reactor to 75-80° C., and at the same time, stirring the crude alkyl glycoside, magnesium sulfate and liquid alkali in the reactor to obtain a mixed raw material; 3) Open the second and fourth control valves, start the circulation pump, and keep the working temperature of the reactor at 75-80°C. Under the action of the circulation pump, the hydrogen peroxide in the hydrogen peroxide storage tank is output through the flow meter, and when the output reaches the set amount, close the fourth control valve, and the hydrogen peroxide output from the hydrogen peroxide storage tank and the mixed raw material output from the reactor are circulated and reacted for 14-17 hours through the first pipeline, the second pipeline, and the reactor in sequence to obtain an alkyl glycoside product; 4) Turn off the circulation pump, open the third control valve, start the feed pump, and input the alkyl glycoside product obtained by the reaction into the alkyl glycoside receiving tank.

3. The method for bleaching and decolorizing an alkyl polyglycoside according to claim 2, characterized in that: The mass ratio of magnesium sulfate to crude alkyl glycoside is 0.1-0.5:100, the mass ratio of liquid alkali to crude alkyl glycoside is 5-15:100, and the mass ratio of hydrogen peroxide to crude alkyl glycoside is 5-15:

100.

4. The method for bleaching and decolorizing an alkyl polyglycoside according to claim 2, characterized in that: The flow rate of the metering pump is 0-2000 kg / h, and the pressure is 0.1-1.0 MPa.

5. The method for bleaching and decolorizing an alkyl polyglycoside according to claim 2, characterized in that: The flow rate of the flow meter is 0~250kg / h, and the pressure is 0.1~1.0MPa.

6. The method for bleaching and decolorizing an alkyl polyglycoside according to claim 2, characterized in that: The crude alkyl glycoside is a dark alkyl glycoside aqueous solution with a concentration range of 50% to 80%.

7. The method for bleaching and decolorizing an alkyl polyglycoside according to claim 2, characterized in that: The alkyl glycoside used is C8-14 alkyl glycoside.

8. The method for bleaching and decolorizing an alkyl polyglycoside according to claim 2, characterized in that: The concentration of hydrogen peroxide is 25-35%.

9. The method for bleaching and decolorizing an alkyl polyglycoside according to claim 2, characterized in that: The liquid alkali is a sodium hydroxide aqueous solution with a concentration of 30-35%.

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