A kind of production process of hydroxyacetone

Abstract

The present invention relates to a production process of hydroxyacetone, and relates to the technical field of chemical synthesis, wherein glycerol, an organic solvent, and a supported catalyst are uniformly mixed, reacted at 170 to 220° C. for at least 2 hours, filtered to obtain a filtrate and a solid, and the filtrate is rectified to obtain hydroxyacetone, wherein the supported catalyst is prepared by an impregnation method, comprising an active component having a content of 20 to 40% and a carrier having a content of 60 to 80%, the active component of the supported catalyst comprising aluminum, copper, chromium, and zinc, and the carrier comprising aluminum oxide, zeolite, zirconium dioxide, and calcium oxide. The present invention can improve the conversion rate of glycerol, while improving the selectivity and purity of hydroxyacetone, extending the service life of the catalyst, and thereby improving the production efficiency of hydroxyacetone.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to a production process of hydroxyacetone. Background Art

[0002] Hydroxyacetone, also known as acetol, is mainly used in the synthesis of pharmaceutical intermediates, spices, dyes, food additives, etc. It is an important raw material for the synthesis of acetals and ketals, the digestive system drug cimetidine, quinolone antibiotics, and the antipyretic and analgesic drug aspirin acetone ester.

[0003] In the prior art, the preparation methods of hydroxyacetone mainly include the following: ① using electrolytic silver to catalyze the oxidation of propylene glycol to obtain α-hydroxyacetone and acetone aldehyde, which has high selectivity, but has high reaction requirements, expensive catalysts, and low product yields; ② esterification and hydrolysis of halogenated acetone: using chloroacetone or bromoacetone for esterification and alcoholysis, the reaction conditions are mild, but the cost of raw materials is high, and both are irritating tear-inducing substances, which are highly polluting; ③ hydrolysis of acetone in the presence of high-valent iodine compounds: the reaction conditions are mild and the cost is high; other methods include dehydration of glycerol, oxidation of propylene glycol, condensation of formaldehyde and acetaldehyde, addition of allyl alcohol or propargyl alcohol to water, and oxidative ring-opening of 1,2-propylene oxide.

[0004] The Chinese patent with publication number CN109896941B proposes a method for synthesizing hydroxyacetone using a vanadium-based catalyst, which uses carbohydrates as raw materials, and the reaction conditions are high temperature and pressure, and is degraded and hydrogenated under the action of a carrier loaded with a vanadium-containing catalyst and a hydrogenation active metal to obtain hydroxyacetone. The vanadium-containing catalyst and active metal ruthenium used in the method are both relatively expensive, and are prone to gradual deactivation during use, and have certain toxicity, making them difficult to use for industrial production. At the same time, the selectivity of hydroxyacetone is relatively low.

[0005] The Chinese patent with publication number CN102070422B proposes a method for preparing acetol and 1,2-propylene glycol by dehydrating and hydrogenating glycerol, which uses glycerol to dehydrate under a copper-based catalyst and hydrogen atmosphere at high temperature to prepare acetol. The copper-based catalyst is a soluble copper salt solution impregnated with an alumina or silicon oxide carrier. The conversion rate of glycerol and the yield of acetol are both low, and further refining is required to improve the purity of acetol. The Chinese patent with publication number CN102781897B proposes a method for preparing hydroxyacetone or propylene glycol, which uses nitrogen or hydrogen to purge at high temperature and pressure to prepare a nanostructured catalyst combination to synthesize hydroxyacetone with high selectivity, but the catalyst preparation time is long and the conversion rate of glycerol is low.

[0006] The Chinese patent with publication number CN114315550B proposes a one-pot synthesis method of hydroxyacetone, which comprises mixing acetone, alkali metal bromide, potassium carbonate and tetrabutylammonium bromide, adding hydrogen peroxide to react, and obtaining hydroxyacetone, wherein the alkali metal bromide is sodium bromide or potassium bromide. The reaction conditions are mild, but the dripping speed and temperature need to be strictly controlled, otherwise the byproduct polyhydroxyacetone will increase, and the product yield will be reduced. In addition, bromide and tetrabutylammonium bromide are corrosive to equipment or skin, and are difficult to be used in industrial production.

[0007] With respect to the above technical scheme, the main problems in preparing hydroxyacetone are that catalysts with different activities have low conversion rates or poor selectivity, are prone to coking and deactivation under long-term high-temperature reactions, and require frequent activation or preparation, resulting in low production efficiency. Summary of the invention

[0008] In order to improve the production efficiency of hydroxyacetone, the present invention provides a production process of hydroxyacetone.

[0009] The present invention provides a production process of hydroxyacetone, which adopts the following technical scheme:

[0010] A production process of hydroxyacetone, comprising uniformly mixing glycerol, an organic solvent and a supported catalyst, reacting at 170-220° C. for at least 2 hours, filtering to obtain a filtrate and a solid, rectifying the filtrate to obtain hydroxyacetone, and recovering the supported catalyst for standby use;

[0011] Wherein, the mass ratio of propylene glycol, organic solvent and supported catalyst is 1:(5-10):(0.01-0.5);

[0012] Among them, the supported catalyst is prepared by impregnation method, including 20-40% active components and 60-80% carrier, the active components include aluminum, copper and chromium, the mass ratio of aluminum, copper and chromium is 1: (0.1-0.5): (0.1-0.5), the carrier includes alumina and zeolite, the mass ratio of alumina to zeolite is 1: (0.5-1).

[0013] By adopting the above technical solution, copper is more active than aluminum and is easy to react with other substances to cause the deactivation of the catalyst, reduce the stability and selectivity of the catalyst, and affect the regeneration performance. Aluminum has better stability and activity. The aluminum content in the active component of the supported catalyst is higher than the copper content, which can increase the number of sites on the catalyst surface, which is beneficial to improving the activity and selectivity of the catalyst, reducing the occurrence of side reactions, increasing the yield and purity of the product, and improving the catalyst's resistance to carbon deposition, thereby improving the stability and activity of the catalyst; adding a small amount of chromium to the active component is beneficial to adding additional active sites and increasing the number of reaction centers on the catalyst surface, thereby improving the activity of the catalyst. The presence of chromium is beneficial to It promotes the selective conversion of propylene glycol into hydroxyacetone, improves product selectivity, and inhibits the occurrence of side reactions. At the same time, chromium has certain antioxidant properties, which is beneficial to improving the heat resistance and stability of the catalyst. Compared with copper-based or molecular sieve carriers used in traditional catalysts, alumina and zeolite can provide more active sites and surface area, promote the uniform dispersion of active components on the carrier, and improve catalytic efficiency. Zeolite has a large surface area and pore structure, which can increase the adsorption rate of the catalyst surface, accelerate the reaction rate, and improve the reaction efficiency. At the same time, zeolite and alumina have good thermal stability and corrosion resistance, which can increase the stability and durability of the catalyst, extend its service life, and thus improve the production efficiency of hydroxyacetone.

[0014] Optionally, the active component also includes zinc, and the mass ratio of aluminum to zinc is 1:(0.01-0.2).

[0015] By adopting the above technical scheme, a small amount of zinc is added to the active component, and zinc can form a relatively stable phase system with copper and aluminum, further improving the activity of the catalyst, promoting the formation and conversion of reaction intermediates, thereby increasing the reaction rate and the yield and purity of the product, while improving the thermal stability of the catalyst, extending its service life, and thereby improving the production efficiency of hydroxyacetone.

[0016] Optionally, the carrier further comprises zirconium dioxide, and the mass ratio of alumina to zirconium dioxide is 1:(0.05-0.2).

[0017] By adopting the above technical scheme, zirconium dioxide has a higher melting point and thermal stability. Adding a certain amount of zirconium dioxide to the alumina carrier is beneficial to improving the high temperature resistance of the catalyst, improving the thermal stability and mechanical strength of the carrier, and increasing the reuse time of the catalyst. At the same time, it is beneficial to improve the pore structure and surface properties of the alumina carrier, improve the dispersibility and reaction activity of the catalyst, improve the anti-poisoning performance, and thus improve production efficiency.

[0018] Optionally, the carrier also includes calcium oxide, and the mass ratio of aluminum oxide to calcium oxide is 1:(0.01-0.05).

[0019] By adopting the above technical solution, calcium oxide can provide certain alkaline sites, promote the increase in the number of active sites on the catalyst surface, thereby improving the activity and selectivity of the reaction, which is beneficial to accelerate the reaction rate and increase the conversion rate of propylene glycol. Calcium oxide is not easy to deactivate in the medium temperature range and has a certain thermal stability at a temperature of about 200°C, which can further increase the reuse time of the catalyst and thus improve production efficiency.

[0020] Optionally, the water content of the glycerol is less than 5%, and the organic solvent is ethanol.

[0021] By adopting the above technical scheme, the presence of water in propylene glycol easily leads to a decrease in its solubility in organic solvents, thereby affecting the reaction process of the reaction materials and causing changes in the reaction rate. High water content easily reduces the stability of the catalyst, shortens the service life of the catalyst, reduces the selectivity of the product, and causes a decrease in product purity or a decrease in yield. Therefore, the use of propylene glycol with a lower water content is beneficial to increasing the reaction rate and improving the selectivity of the product. Ethanol as a reaction solvent has higher stability and lower toxicity, can provide milder reaction conditions, has stronger polarity, and is beneficial to increasing the reaction rate and selectivity, thereby improving production efficiency.

[0022] Optionally, the reaction duration is further 3 h to 5 h.

[0023] By adopting the above technical scheme, extending the reaction time is beneficial to improving the conversion rate of propylene glycol and the selectivity of the product, thereby improving the purity and yield of the product. Further extending the reaction time is likely to lead to the formation of side reactions, reducing the purity and yield of the product. Therefore, controlling the reaction time within a certain range is beneficial to improving production efficiency.

[0024] Optionally, after the filtrate is obtained by filtration, the filtrate is washed with sodium bicarbonate solution and sodium chloride solution until it becomes neutral, extracted with ethanol for multiple times, dried with anhydrous sodium sulfate, and then distilled.

[0025] By adopting the above technical scheme, some impurities and residual moisture are removed through washing, extraction and drying, which is beneficial to improving the stability of the product, reducing the loss of impurities and moisture to the product, improving the stability of the product, and then improving the purity and yield of the product and improving production efficiency.

[0026] Optionally, the preparation steps of the supported catalyst include:

[0027] Step a: uniformly mix the carrier powder, active components, organic solvent and nitrate solution, and stir at a constant temperature for 5 to 10 hours, wherein the nitrate solution includes one or more of copper nitrate, aluminum nitrate and chromium nitrate;

[0028] Step b: filtering and removing the filtrate to obtain a precipitate, and drying the precipitate at 100-120° C. for at least 2 h;

[0029] Step c: calcining at 300-500° C. for at least 3 hours, and obtaining a supported catalyst after cooling.

[0030] By adopting the above technical scheme, constant temperature stirring for 5 to 10 hours is conducive to more uniform loading of the active components on the carrier, improving the uniformity and dispersibility of the catalyst, and thus increasing the loading amount of the catalyst. The dried precipitate is dried and calcined at a lower temperature. Compared with the high-temperature drying and calcination in the traditional impregnation method, it is conducive to reducing the side reactions or instability of the catalyst components caused by high temperature, simplifying the preparation process, shortening the preparation time, and at the same time improving the catalytic performance and stability of the supported catalyst, thereby improving the production efficiency.

[0031] Optionally, the temperature of the constant temperature stirring in step a is 25 to 60° C., and the calcination time in step c is 8 to 14 hours.

[0032] By adopting the above technical scheme, the constant temperature stirring temperature in step a is 25-60° C., which is conducive to uniformly loading the active components on the carrier and improving the uniformity and dispersibility of the catalyst. The calcination time in step c is 8-14 hours. Compared with the longer calcination time in the traditional impregnation method, it can save time, reduce energy consumption and equipment costs, and reduce side reactions caused by high temperature, thereby maintaining the activity and stability of the catalyst, thereby improving the catalytic performance and selectivity of the catalyst and improving production efficiency.

[0033] Optionally, the nitrate solution is a 0.1-0.5 mol / L aluminum nitrate solution.

[0034] By adopting the above technical scheme, aluminum nitrate is usually used as an aluminum precursor. When preparing a supported catalyst, aluminum nitrate can be impregnated as an active component or an auxiliary component to enhance the activity of the catalyst, as well as improve the stability and thermal properties of the catalyst, and is suitable for high-temperature reactions. At the same time, it also has a certain effect on the structure and surface properties of the catalyst, which is beneficial to improve the selectivity of the product and thus improve production efficiency.

[0035] In summary, the present invention includes at least one of the following beneficial technical effects:

[0036] 1. By setting the active component distribution ratio of the supported catalyst, the aluminum content in the active component of the supported catalyst is higher than the copper content, which can increase the number of catalyst surface sites and improve the activity, selectivity and stability of the catalyst. A small amount of chromium is beneficial to increase additional active sites, increase the number of reaction centers on the catalyst surface, improve the activity of the catalyst, improve product selectivity, and inhibit the occurrence of side reactions. At the same time, chromium has certain antioxidant properties, which is beneficial to improve the heat resistance and stability of the catalyst. A small amount of zinc can form a relatively stable phase system with copper and aluminum, further improve the activity of the catalyst, promote the generation and conversion of reaction intermediates, and improve the thermal stability of the catalyst, thereby improving the production efficiency of hydroxyacetone.

[0037] 2. By setting the loading group distribution ratio of the loaded catalyst, compared with the copper-based or molecular sieve carriers used in traditional catalysts, alumina and zeolite can provide more active sites and surface areas, promote the uniform dispersion of active components on the carrier, and improve the catalytic efficiency. Zeolite and alumina have good thermal stability and corrosion resistance, which can increase the stability and durability of the catalyst. Zirconium dioxide has a high melting point and thermal stability, which is beneficial to improve the thermal stability and mechanical strength of the carrier, increase the reuse time of the catalyst, and improve the anti-poisoning performance. Calcium oxide can provide certain alkaline sites and promote the increase in the number of active sites on the catalyst surface, thereby improving the activity and selectivity of the reaction. Calcium oxide is not easy to deactivate in the medium temperature range, which can further increase the reuse time of the catalyst. By setting the active group distribution ratio and the loading group distribution ratio, the selectivity can be further improved on the basis of improving the conversion rate, thereby improving the production efficiency.

[0038] 3. Through the setting of propylene glycol water content and organic solvent, high water content is easy to affect the reaction process, reduce the stability of the catalyst, shorten the service life of the catalyst, reduce the selectivity of the product, and promote the occurrence of side reactions. Therefore, the use of anhydrous propylene glycol is beneficial to increase the reaction rate and improve the selectivity of the product. Compared with methanol and 2-propanol, ethanol has higher stability and lower toxicity, can provide milder reaction conditions, has stronger polarity, and is conducive to improving the reaction rate and selectivity, thereby improving production efficiency. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below with reference to the embodiments.

[0040] Example 1: Preparation of a supported catalyst: the carrier is 25% alumina and 25% zeolite, the active components are 40% aluminum and 10% copper, the carrier powder, the active components and ethanol are evenly mixed, 0.2 mol / L aluminum nitrate solution is added, stirred at a constant temperature of 25°C for 5 hours, the filtrate is filtered to obtain a precipitate, the precipitate is dried at 110°C for 3 hours, calcined at 300°C in a nitrogen atmosphere for 3 hours, and cooled to obtain a supported catalyst.

[0041] 20 g of pure glycerol and 10 g of supported catalyst were added to 80 g of ethanol and stirred evenly. The mixture was reacted at 200 °C for 3 h. The filtrate and solid were obtained by filtration. The filtrate was distilled to obtain hydroxyacetone. The solid was the supported catalyst and was recovered for later use. The filtrate was washed with sodium bicarbonate solution and sodium chloride solution until neutral. The mixture was extracted with ethanol twice and dried with anhydrous sodium sulfate before distillation. The conversion rate of glycerol was 18% and the selectivity of hydroxyacetone was 77%.

[0042] Example 2: A supported catalyst and hydroxyacetone were prepared in the same manner as in Example 1. The difference from Example 1 was that the active components of the supported catalyst were 20% aluminum and 30% copper, the conversion rate of glycerol was 22%, and the selectivity of hydroxyacetone was 65%.

[0043] Example 3: A supported catalyst and hydroxyacetone were prepared in the same manner as in Example 1. The difference from Example 1 was that the active components of the supported catalyst were 30% aluminum, 15% copper and 5% chromium, the conversion rate of glycerol was 38%, and the selectivity of hydroxyacetone was 86%.

[0044] Example 4: A supported catalyst and hydroxyacetone were prepared in the same manner as in Example 1. The difference from Example 1 was that the active components of the supported catalyst were 30% aluminum, 15% copper, 4% chromium and 1% zinc, the conversion rate of glycerol was 41%, and the selectivity of hydroxyacetone was 94%.

[0045] By comparing Example 1, Example 2, Example 3 and Example 4, it can be seen that copper is more active than aluminum and is easy to react with other substances to cause the deactivation of the catalyst. Increasing the proportion of copper is easy to reduce the stability and selectivity of the catalyst and affect the regeneration performance. Aluminum has better stability and activity. The content of aluminum in the active component of the supported catalyst is higher than that of copper, which can increase the number of catalyst surface sites, which is beneficial to improving the activity and selectivity of the catalyst, reducing the occurrence of side reactions, increasing the yield and purity of the product, and improving the catalyst's resistance to carbon deposition, thereby improving the stability and activity of the catalyst;

[0046] Adding a small amount of chromium to the active components is beneficial to increase additional active sites and the number of reaction centers on the catalyst surface, thereby improving the activity of the catalyst. The presence of chromium is beneficial to promoting the selective conversion of glycerol into hydroxyacetone, improving product selectivity, and inhibiting the occurrence of side reactions. At the same time, chromium has certain antioxidant properties, which is beneficial to improving the heat resistance and stability of the catalyst.

[0047] By adding a small amount of zinc to the active components, zinc can form a relatively stable phase system with copper and aluminum, further improving the activity of the catalyst, promoting the formation and conversion of reaction intermediates, thereby increasing the reaction rate and the yield and purity of the product, while also improving the thermal stability of the catalyst, extending its service life, and thereby improving the production efficiency of hydroxyacetone.

[0048] The experimental results are shown in the following table:

[0049] Example Active ingredients Glycerol conversion rate Selectivity 1 40% aluminum + 10% copper 18% 77% 2 20% aluminum + 30% copper 22% 65% 3 30% aluminum + 15% copper + 5% chromium 38% 86% 4 30% aluminum + 15% copper + 4% chromium + 1% zinc 41% 94%

[0050] Example 5: A supported catalyst and hydroxyacetone were prepared in the same manner as in Example 4. The difference from Example 4 was that the carrier components of the supported catalyst were 15% alumina and 35% zeolite, the conversion rate of glycerol was 40%, the selectivity of hydroxyacetone was 90%, and the supported catalyst was reused multiple times, and its reuse time was 500 h.

[0051] Example 6: A supported catalyst and hydroxyacetone were prepared in the same manner as in Example 4. The difference from Example 4 was that the carrier components of the supported catalyst were 30% alumina and 20% zeolite, the conversion rate of glycerol was 42%, the selectivity of hydroxyacetone was 93%, and the supported catalyst was reused multiple times, and its reuse time was 500 h.

[0052] Example 7: A supported catalyst and hydroxyacetone were prepared in the same manner as in Example 4. The difference from Example 4 was that the carrier components of the supported catalyst were 30% alumina, 15% zeolite and 5% zirconium dioxide, the conversion rate of glycerol was 47%, the selectivity of hydroxyacetone was 95%, and the supported catalyst was reused multiple times, and its reuse time was 600 h.

[0053] Example 8: A supported catalyst and hydroxyacetone were prepared in the same manner as in Example 4. The difference from Example 4 was that the carrier components of the supported catalyst were 30% alumina, 15% zeolite, 4% zirconium dioxide and 1% calcium oxide, the conversion rate of glycerol was 49%, the selectivity of hydroxyacetone was 96%, and the supported catalyst was reused multiple times, and its reuse time was 620 h.

[0054] By comparing Example 5, Example 6, Example 7 and Example 8, it can be seen that compared with copper-based or molecular sieve carriers used in traditional catalysts, alumina and zeolite can provide more active sites and surface areas, promote the uniform dispersion of active components on the carrier, and improve the catalytic efficiency. Zeolite has a large surface area and pore structure, which can increase the adsorption rate of the catalyst surface, accelerate the reaction speed, and improve the reaction efficiency. At the same time, zeolite and alumina have good thermal stability and corrosion resistance, which can increase the stability and durability of the catalyst and extend its service life.

[0055] Zirconium dioxide has a high melting point and thermal stability. Adding a certain amount of zirconium dioxide to an alumina carrier is beneficial to improving the high temperature resistance of the catalyst, improving the thermal stability and mechanical strength of the carrier, and increasing the reuse time of the catalyst. It is also beneficial to improving the pore structure and surface properties of the alumina carrier, improving the dispersibility and reaction activity of the catalyst, and improving the anti-poisoning performance.

[0056] Calcium oxide can provide certain alkaline sites, promote the increase in the number of active sites on the catalyst surface, thereby improving the activity and selectivity of the reaction, which is beneficial to accelerate the reaction rate and increase the conversion rate of propylene glycol. Calcium oxide is not easy to deactivate in the medium temperature range and has a certain thermal stability at a temperature of about 200°C, which can further increase the reuse time of the catalyst and thus improve production efficiency.

[0057] The experimental results are shown in the following table:

[0058] Example Carrier components Glycerol conversion rate Selectivity Reuse time 5 15% alumina + 35% zeolite 40% 90% 500h 6 30% alumina + 20% zeolite 42% 93% 500h 7 30% alumina + 15% zeolite + 5% zirconium dioxide 47% 95% 600h 8 30% alumina + 15% zeolite + 4% zirconium dioxide + 1% calcium oxide 49% 96% 620h

[0059] Example 9: A supported catalyst and hydroxyacetone were prepared in the same manner as Example 8. The difference from Example 8 was that 5 wt % glycerol was used as a reactant, the conversion rate of glycerol was 51%, and the selectivity of hydroxyacetone was 96%.

[0060] Example 10: A supported catalyst and hydroxyacetone were prepared in the same manner as Example 8. The difference from Example 8 was that 10 wt % glycerol was used as a reactant, the conversion rate of glycerol was 54%, and the selectivity of hydroxyacetone was 91%.

[0061] Example 11: A supported catalyst and hydroxyacetone were prepared in the same manner as Example 8. The difference from Example 8 was that 20 wt % glycerol was used as a reactant, the conversion rate of glycerol was 58%, and the selectivity of hydroxyacetone was 78%.

[0062] By comparing Example 8, Example 9, Example 10 and Example 11, it can be seen that the presence of water in propylene glycol easily leads to a decrease in its solubility in organic solvents, thereby affecting the reaction process of the reaction materials and causing a change in the reaction rate. In the reaction in a high temperature and high pressure environment involving a metal catalyst, a high water content easily reduces the stability of the catalyst, shortens the service life of the catalyst, reduces the selectivity of the product, promotes the occurrence of side reactions, and leads to a decrease in product purity or a decrease in yield. Therefore, the use of anhydrous propylene glycol is beneficial to increasing the reaction rate, increasing the selectivity of the product, and thereby improving production efficiency.

[0063] The experimental results are shown in the following table:

[0064] Example Glycerol water content Glycerol conversion rate Selectivity 8 0wt% 49% 96% 9 5wt% 51% 96% 10 10wt% 54% 91% 11 20wt% 58% 78%

[0065] Example 12: A supported catalyst and hydroxyacetone were prepared in the same manner as Example 8. The difference from Example 8 was that methanol was used as the reaction solvent, the conversion rate of glycerol was 55%, and the selectivity of hydroxyacetone was 92%.

[0066] Example 13: A supported catalyst and hydroxyacetone were prepared in the same manner as Example 8. The difference from Example 8 was that 2-propanol was used as the reaction solvent, the conversion rate of glycerol was 56%, and the selectivity of hydroxyacetone was 89%.

[0067] Example 14: A supported catalyst and hydroxyacetone were prepared in the same manner as Example 8. The difference from Example 8 was that 20% methanol and 80% ethanol were used as reaction solvents, the conversion rate of glycerol was 52%, and the selectivity of hydroxyacetone was 94%.

[0068] By comparing Example 8, Example 12, Example 13 and Example 14, it can be seen that methanol or 2-propanol is usually used as a solvent for the reaction in the prior art. Methanol is a strong dehydrating agent, which is likely to have a certain impact on the selectivity of the reaction product and is not conducive to the formation of the target product. Methanol is flammable and explosive and is a toxic substance. When the product is applied to food or medicine, the content needs to be strictly controlled to avoid contact;

[0069] 2-Propanol is more likely to undergo side reactions under reaction conditions, resulting in poor product selectivity. The 2-propanol molecule is larger, which can easily affect the mass transfer performance of the reaction, resulting in reduced reaction efficiency. In addition, the cost of 2-propanol is relatively high, which limits its large-scale production. Therefore, ethanol is selected as the reaction solvent, which has higher stability and lower toxicity, can provide milder reaction conditions, has stronger polarity, and is conducive to improving the reaction rate and selectivity, thereby improving production efficiency.

[0070] The experimental results are shown in the following table:

[0071] Example Organic solvents Glycerol conversion rate Selectivity 8 Ethanol 49% 96% 12 Methanol 55% 92% 13 2-Propanol 56% 89% 14 20% methanol + 80% ethanol 52% 94%

[0072] Example 15: A supported catalyst and hydroxyacetone were prepared in the same manner as Example 8. The difference from Example 8 was that the reaction time for preparing hydroxyacetone was 2 h, the conversion rate of glycerol was 45%, and the selectivity of hydroxyacetone was 94%.

[0073] Example 16: A supported catalyst and hydroxyacetone were prepared in the same manner as in Example 8. The difference from Example 8 was that the reaction time for preparing hydroxyacetone was 4 h, the conversion rate of glycerol was 51%, and the selectivity of hydroxyacetone was 97%.

[0074] Example 17: A supported catalyst and hydroxyacetone were prepared in the same manner as Example 8. The difference between Example 17 and Example 8 was that the reaction time for preparing hydroxyacetone was 5 h, the conversion rate of glycerol was 53%, and the selectivity of hydroxyacetone was 97%.

[0075] By comparing Example 8, Example 15, Example 16 and Example 17, it can be seen that extending the reaction time is beneficial to improving the conversion rate of propylene glycol and the selectivity of the product, thereby improving the purity and yield of the product. Further extending the reaction time is likely to lead to the formation of side reactions and reduce the purity of the product. Therefore, controlling the reaction time within a certain range is beneficial to improving production efficiency.

[0076] The experimental results are shown in the following table:

[0077] Example Reaction time Glycerol conversion rate Selectivity 8 3h 49% 96% 15 2h 45% 94% 16 4h 51% 97% 17 5h 53% 97%

[0078] Example 18: A supported catalyst and hydroxyacetone were prepared in the same manner as Example 8. The difference from Example 8 was that the constant temperature stirring temperature was 30°C, the calcination time was 4 h, the glycerol conversion rate was 52%, and the hydroxyacetone selectivity was 98%.

[0079] Example 19: A supported catalyst and hydroxyacetone were prepared in the same manner as Example 8. The difference from Example 8 was that the constant temperature stirring temperature was 30°C, the calcination time was 8 h, the glycerol conversion rate was 56%, and the hydroxyacetone selectivity was 97%.

[0080] Example 20: A supported catalyst and hydroxyacetone were prepared in the same manner as Example 8. The difference from Example 8 was that the constant temperature stirring temperature was 45°C, the calcination time was 8 h, the glycerol conversion rate was 57%, and the hydroxyacetone selectivity was 97%.

[0081] Example 21: A supported catalyst and hydroxyacetone were prepared in the same manner as Example 8. The difference from Example 8 was that the constant temperature stirring temperature was 30°C, the calcination time was 12 h, the glycerol conversion rate was 57%, and the hydroxyacetone selectivity was 96%.

[0082] By comparing Example 8, Example 18, Example 19, Example 20 and Example 21, it can be seen that the constant temperature stirring temperature is 25-60°C and the calcination time is 8-14h. Compared with the higher stirring temperature and longer calcination time in the traditional impregnation method, it is beneficial to evenly load the active components on the carrier, improve the uniformity and dispersibility of the catalyst, reduce the side reactions caused by high temperature, thereby maintaining the activity and stability of the catalyst, and further improving the catalytic performance and selectivity of the catalyst, simplifying the preparation process, saving time, reducing energy consumption and equipment costs, and improving production efficiency.

[0083] The experimental results are shown in the following table:

[0084] Example catalyst Glycerol conversion rate Selectivity 8 Stirring + calcining at 25℃ for 3h 49% 96% 18 Stirring at 30℃ + calcination for 4h 52% 98% 19 Stirring at 30℃ + calcination for 8h 56% 97% 20 Stirring at 45℃ + calcination for 8h 57% 97% 21 Stirring at 30℃ + calcination for 12h 57% 96%

[0085] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A production process for hydroxyacetone, characterized in that: Mix glycerol, an organic solvent and a supported catalyst uniformly, react at 170-220° C. for at least 2 hours, filter to obtain a filtrate and a solid, distill the filtrate to obtain hydroxyacetone, and the solid is a supported catalyst, which is recovered for later use; The mass ratio of glycerol, organic solvent and supported catalyst is 1:(5-10):(0.01-0.5); the water content of glycerol is less than 5%, and the organic solvent is ethanol; Among them, the supported catalyst is prepared by impregnation method, including 50% active components and 50% carrier, the active components are aluminum, copper, chromium, zinc, the mass ratio of aluminum, copper, chromium, zinc is 1: (0.1 ~ 0.5): (0.1 ~ 0.5): (0.01 ~ 0.2), the carrier includes alumina and zeolite, the mass ratio of alumina to zeolite is 1: (0.5 ~ 1).

2. A production process for hydroxyacetone according to claim 1, characterized in that: The carrier also includes zirconium dioxide, and the mass ratio of aluminum oxide to zirconium dioxide is 1:(0.05-0.2).

3. A production process for hydroxyacetone according to claim 1, characterized in that: The carrier also includes calcium oxide, and the mass ratio of aluminum oxide to calcium oxide is 1: (0.01-0.05).

4. A production process for hydroxyacetone according to claim 1, characterized in that: The reaction time is 3 h to 5 h.

5. A production process for hydroxyacetone according to claim 1, characterized in that: After the filtrate is obtained by filtration, the filtrate is washed with sodium bicarbonate solution and sodium chloride solution until it becomes neutral, extracted with ethanol for multiple times, dried with anhydrous sodium sulfate, and then distilled.