Production process of hydrogen peroxide

Production of hydrogen peroxide using the anthraquinone process technology. Serial number: 86008. Library of Congress classification number: TQ123.6. Technical level: Advanced at the provincial level. Main implementing unit: Kunming Hydrogen Peroxide Plant. Key personnel: Mu Yunqing, Xu Shaozeng, Li Meila, Tan Renjian, Bian Zulan. Awards received: Second Prize for Scientific and Technological Progress at the municipal level. Address: Jinmasi, Kunming. Postal code: 650216. Brief description of the achievement: Hydrogen peroxide is an important chemical product; the main methods for its production currently include electrolysis, oxygen cathode reduction, alcohol oxidation, direct hydrogen-oxygen combination, and the anthraquinone method. Compared with the electrolytic method currently used in most parts of China and the auto-oxidation method using pure oxygen and 2-ethylanthraquinone derivatives, this process has the following advantages: 1. When producing hydrogen peroxide by the electrolytic method, the electricity consumption per ton is as high as 12,000 kWh; it causes severe pollution in the form of waste gases, waste water, and waste solids. Moreover, platinum metal is required (4 g of platinum per ton), resulting in a cost of ≥2,460 yuan per ton ； This process requires only 250 kWh of electricity per ton, is pollution-free, and does not require platinum. The cost per ton is ≤ 1,400 yuan. 2. The automatic oxidation of anthraquinone derivatives using pure oxygen to produce hydrogen peroxide requires pure oxygen (with an oxygen cost of 350 yuan per ton of hydrogen peroxide), as well as protective nitrogen gas (at 120 yuan per ton of hydrogen peroxide); this method has low safety levels and high costs ； This process uses air instead of oxygen, resulting in high safety and low material consumption. 3. By using an SC-3A type colorimetric chromatograph and a proprietary analysis method, the analysis of working solution components is fast and reliable, avoiding the need for expensive instruments or the mercury toxicity associated with polarography. As proven by assessments, the annual production volume can exceed the designed capacity of 300 tons and reach over 400 tons ； The profit is approximately 250,000 yuan per year, and the products meet the first-class standards of HG1616-79. This post was last edited by DAC The army rules the world on 2007-7-16 21:01.]

Research Progress on the Production of Hydrogen Peroxide by Anthraquinone Method Chen Guanqun, Zhou Tao, Zeng Ping, Ge Zhiqiang (School of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083) Abstract: Hydrogen peroxide is a green chemical product that is widely used in fields such as medicine, military industry, chemical synthesis, textiles, papermaking, environmental protection, food processing, metallurgy, and agriculture. This article introduces the main production methods of hydrogen peroxide, and discusses the research progress in the production of hydrogen peroxide via the anthraquinone method from the perspectives of catalysts, solvents, and hydrogenation processes. It points out that replacing the fixed-bed hydrogenation process with a fluidized-bed hydrogenation process in the anthraquinone hydrogenation route for hydrogen peroxide production will be the development trend in China’s hydrogen peroxide industry. Keywords: hydrogen peroxide ； anthraquinone method ； catalyst ； Solvent Chinese Library Classification Number: TQ123.6 Document Code: A Research on the Production of Hydrogen Peroxide through the Anthraquinone Process CHEN Guan-qun, ZHOU Tao, ZENG Ping, GE Zhi-qiang (College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, Hunan, China) Abstract: Hydrogen peroxide is a cleaner chemical product that is widely used in the pharmaceutical industry, the military industry, the synthesis of chemical products, the textile industry, paper manufacturing, environmental protection, the food industry, the metallurgical industry, and agriculture. This paper reviews the main methods and research progress related to the production of hydrogen peroxide via the anthraquinone process, including the hydrogenation of anthraquinone as well as the use of catalysts and solvents. It is suggested that the use of a fluidized bed process rather than a fixed bed process in the hydrogenation of anthraquinone represents the future trend in hydrogen peroxide production. Keywords: hydrogen peroxide; anthraquinone process; catalyst; solvent Hydrogen peroxide is a green chemical product; its production and use generate almost no pollution, which is why it is considered a “clean” chemical product, and its application prospects are increasingly promising. Initially, hydrogen peroxide was used only in the pharmaceutical and military industries; it has since been applied in a wide range of fields such as chemical synthesis, textiles, papermaking, environmental protection, food processing, medicine, metallurgy, and agriculture, with market demand continuing to grow. Hydrogen peroxide is mainly used in three fields: bleaching, chemical synthesis, and environmental protection. And compared to related products, it exhibits an absolute advantage. For example, H2O2 is used for bleaching various types of fabrics, not only because it causes little damage to fiber strength, prevents the fabrics from yellowing again, and results in a pleasant feel, but also because it does not pollute the environment ； In chemical synthesis, H2O2 can be used to produce various inorganic peroxides; the most important of these are sodium perborate and sodium percarbonate. Both are additives in detergents, possessing bleaching and disinfecting properties, and are used in large quantities. H2O2 can be used to treat toxic wastewater, with sulfides, cyanides, and phenolic compounds being those that are treated the most and most effectively. H2O2 can also be used to treat toxic exhaust gases such as SO2, NO, H2S, etc., with various treatment methods that yield good results ； Moreover, when using H2O2 to treat toxic pollutants, it has a wide range of application, effective results, and does not cause secondary pollution. In our country, hydrogen peroxide is mainly used in the textile industry ； Moreover, the proportion of hydrogen peroxide consumed in the paper industry is much lower than in Western Europe and the United States ； Especially in the environmental protection industry, the consumption of hydrogen peroxide is relatively high abroad, whereas it is virtually non-existent in our country. Therefore, tapping into the huge potential of hydrogen peroxide as an environmentally friendly product holds great value in our country, and it will also open up broader markets for hydrogen peroxide. 1 Methods for producing hydrogen peroxide 1.1 Anthraquinone method The anthraquinone method is one of the most mature production methods for hydrogen peroxide in the world today; large manufacturers abroad all use this method to produce hydrogen peroxide, and in China as well, this method is almost exclusively used for its preparation. At the beginning of the 20th century, a method was invented to produce hydrogen peroxide by recycling 2-alkylanthraquinones as carriers for hydrogen; subsequent improvements have led to the further refinement of this technology. The process involves preparing a working solution by mixing 2-alkylanthraquinone with an organic solvent; then, under pressure of 0.30 MPa and at a temperature of 55°C to 65°C, hydrogen is introduced for hydrogenation in the presence of a catalyst. Subsequently, counter-current oxidation is carried out with air (or oxygen) at a temperature of 40°C to 44°C. After extraction, regeneration, purification, and concentration, the final product in the form of an H2O2 aqueous solution is obtained. Currently, the Chinese market offers products with mass fractions of 27.5%, 35.0%, and 50.0%. Before the mid-1980s in China, the production of hydrogen peroxide primarily relied on the anthraquinone hydrogenation process using nickel catalysts in stirred-tank reactors. As production capacity continued to increase, the fixed-bed process using palladium catalysts gradually showed its advantages over the stirred-tank process: it features a simpler hydrogenation equipment structure, higher production capacity, no need for frequent catalyst replenishment during operation, better safety performance, and easier handling. With the aid of distributed control system (DCS) technology, the safety performance of such installations can be improved, and this process has become the trend in the development of hydrogen peroxide production ； Recently, almost all new installations and process upgrades in existing plants employ the anthraquinone process, with palladium-catalyzed fixed-bed and nickel-palladium mixed-bed systems being commonly used. To date, there are no domestic literature reports on hydrogenation fluidized beds; only Shanghai Atofina Hydrogen Peroxide Company and Fujian No.1 Chemical Plant have adopted a patented process using palladium-catalyzed hydrogenation fluidized beds by introducing foreign technology. 1.2 New methods for hydrogen peroxide production At present, the technology used for producing hydrogen peroxide via the anthraquinone method is gradually becoming more refined and mature. Its drawback is the use of organic solvents; during the process, hydrogen, oxygen, hydrogen peroxide coexist with these organic solvents, posing certain risks to production. Many research institutions are developing new methods that have lower production costs compared to the anthraquinone method, and are superior to it in certain aspects. The reported new methods for producing hydrogen peroxide include the air cathode method, direct hydrogen-oxygen synthesis method, oxidation of methylbenzyl alcohol, oxidation of isopropanol, fuel cell method, and the method of producing hydrogen peroxide using carbon monoxide in an aqueous solution. However, these new production methods are still in the development and exploration stage, and there are no reports of their industrialization yet. 2 Research progress on the anthraquinone process at home and abroad. The technical advantages of the anthraquinone process for producing hydrogen peroxide mean that this method is currently used in the production of hydrogen peroxide almost everywhere in the world. To further improve and refine the anthraquinone method, research efforts focus on three aspects: the study of catalysts for the hydrogenation process ； Research on solvents ； Research on the anthraquinone hydrogenation process. The author will introduce the progress in the production of hydrogen peroxide via the anthraquinone method at home and abroad from these three aspects. 2.1 Hydrogenation catalysts used in the anthraquinone process for hydrogen peroxide production Hydrogenation catalysts are one of the key technologies in the anthraquinone process. This field has always been one of the hot topics in peroxide research both domestically and internationally. Currently, hydrogenation catalysts for hydrogen peroxide production using the anthraquinone process are mainly divided into two categories: nickel catalysts and palladium catalysts. 2.1.1 Nickel-based catalysts Nickel-based catalysts are produced by treating aluminum-nickel alloy powder with an alkaline solution followed by dehydration using aromatic hydrocarbons, and they exhibit high activity and selectivity. Due to drawbacks such as its tendency to catch fire upon contact with air, the complex structure of the hydrogenator, difficulty in regeneration after failure, sensitivity to trace amounts of O2 and H2O2 in the circulating working fluid, and high susceptibility to poisoning, this catalyst is currently used only in smaller-scale production units and is gradually being phased out; palladium catalysts are instead used in large-scale production facilities. 2.1.2 Palladium-based fixed-bed catalysts For palladium-supported catalysts used in fixed-bed anthraquinone hydrogenation, one of the key factors is the selection of the carrier. The carriers involved include active alumina, active titanium dioxide, silica gel, sodium aluminosilicate, silicoaluminate, alkaline earth metal carbonates, alkaline earth metal phosphates, magnesium aluminum spinel, or magnetite, etc. Currently, alumina is the main carrier used in industrial production. Currently, most hydrogen peroxide manufacturers, both domestically and internationally, use Pd/catalyst support systems; for example, FMC Company employs a granular catalyst of 0.3% Pd/Al2O3. Patent studies have shown that arranging catalysts and inert particles such as Al2O3 in a segmented, cross-pattern within a fixed-bed setup can significantly enhance the catalyst’s production capacity and reduce the formation of degradation products ； MGC Company also uses (0.5%～2%) Pd/Al2O3, etc. Catalysts with large pores and low surface areas can inhibit anthraquinone degradation and improve catalyst selectivity. To improve the utilization rate of active components, with the advancement of research on the distribution of active components on carriers and the maturity of techniques for non-uniform dispersion of catalyst active components, palladium-supported non-uniform eggshell-shaped catalysts have been developed based on these theories and techniques, with the thickness of the palladium-bearing layer being in the micron range. Thinning the catalyst active layer using this technique helps to avoid problems such as deep hydrogenation in trickle-bed reactors, which occur due to the prolonged residence time of anthraquinones in the catalyst pores, thereby improving the catalyst’s selectivity ； At the same time, it achieves the goal of reducing palladium content and the production cost of the catalyst. Cylindrical monoliths and honeycomb catalysts: Cylindrical monolith catalysts have a unique structure, with an emphasis on the overall effect. The entire catalyst is composed of many catalytic units; the geometric shapes of the various catalyst channels are similar, resulting in the same pressure drop as the reaction stream passes through them, as well as the same contact time between the reactants and the catalyst. This prevents uneven reactions in certain areas. Due to the thinness of the catalyst layer and the short distance from the internal pores to the surface, hydrides can easily diffuse out, thereby preventing degradation side reactions. Due to its lower pressure drop compared to traditional catalyst beds, this allows for an increase in hydrogen flow rate as well as in the feed flow rate per unit cross-sectional area of the bed, thereby enhancing material mixing and improving the distribution of fluids within the bed, and ultimately increasing the production capacity of the hydrogenator. The advantages of honeycomb catalysts are similar to those of conventional catalysts: they allow for more efficient use of palladium, increase the rate and selectivity of hydrogenation, and reduce the formation of by-products. The use of honeycomb catalysts and monolithic catalysts in the anthraquinone hydrogenation process has been a research focus in the hydrogen peroxide industry in recent years. This is because these two types of catalysts not only exert the same effects as eggshell-type heterogeneous catalysts in suppressing anthraquinone degradation and reducing palladium content, but they also improve the mass transfer of the reaction materials toward the catalyst surface within the bed, thereby enhancing the overall efficiency of the catalysts in the trickle bed. Akzo Nobel, a major producer of hydrogen peroxide, uses a composite catalyst that consists of multiple sections of cylindrical catalysts. In addition, Huafa Catalyst Co., Ltd. in Suzhou, China, has also developed HFS-1 trilobal and HFY-1 cylindrical palladium catalysts with high activity, good selectivity, high strength, and low operating temperatures. The Liming Chemical Research Institute has successfully developed APC-Q-1 spherical palladium catalysts with low bulk density, high strength, high activity, good selectivity, and a long service life. 2.1.3 Palladium-based suspended-bed catalysts: In addition to fixed-bed reactors, hydrogenation can also be carried out in suspended-bed reactors. Palladium-based catalysts used for slurry-bed hydrogenation have Al2O3 (powder form) or SiO2 (powder form) as carriers, or a carrier-free palladium black catalyst can also be used. Powdered Al2O3 is used as a carrier in the catalyst developed by DuPont for suspension hydrogenation. It uses activated alumina as a carrier, with the particle size of the carrier ranging from 20 to 400 mesh (with 50 to 300 mesh being preferred), and the specific surface area of the catalyst ranging from 25 m2/g to 400 m2/g. When an amorphous SiO2 with a low surface area is used as the carrier for the catalyst, it exhibits good activity and selectivity, reduces the degradation of anthraquinones, and overcomes the disadvantages of γ-Al2O3 such as sensitivity to H2O and easy deactivation, thereby extending the catalyst’s service life. Carrier-free palladium black catalysts can eliminate the effects of carriers, and the softer palladium particles help to avoid wear on the equipment. Studies have shown that when a small amount of transition metals (equivalent to 0.01%–3.0% of the palladium content), such as Fe, Cr, Ni, Ti, Zr, Al, Ce, La, Mg, and Co (with Fe, Cr, and Ni being the most effective), are added during the preparation of palladium black catalysts, this can improve the catalyst’s activity and stability. Patents indicate that nickel catalysts that are corroded but contain active metals such as iron, chromium, molybdenum, and copper exhibit good selectivity; however, it is difficult to regenerate catalysts containing such active metals. Therefore, carrier-free palladium catalysts offer the advantage of being easy to recycle. With the development and utilization of fluidized beds in the hydrogenation process, powdered palladium catalysts are being used more and more often. For example, Solvay Interox, which has the largest production scale for hydrogen peroxide, uses a powdered catalyst of 2% Pd/Al2O3-SiO2-Na2O in its fluidized-bed hydrogenation process. This catalyst features good dispersion, high activity and selectivity, high utilization efficiency, and reduced degradation of anthraquinone ； Another example is the hydrogenation process used by Degussa’s hydrogen peroxide production company, which involves tubular suspension hydrogenators. 100% Pd powder (palladium black) is used as a catalyst, and the spent catalyst can be recycled. Palladium black catalysts offer the advantages of stable performance, no impact from a carrier material, soft particles that do not cause wear on valves that are opened and closed frequently, and low consumption. 2.1.4 Applications of other palladium catalysts: Peroco in Canada uses organic polymers as carriers to which palladium is complexed. This polymer exhibits different solubilities at various temperatures, and its solubility in water can be switched between soluble and insoluble states by adjusting the temperature. The catalyst still maintains good selectivity and a high production capacity. If the carrier is halogenated before loading with palladium, its acidity can be increased. According to Interox’s patent, palladium catalysts prepared using halogenated Al2O3 can suppress unwanted hydrogenation side reactions and the formation of the degradation product anthracene. 2.2 Solvents used in the anthraquinone process for hydrogen peroxide production: The anthraquinone process requires appropriate solvents to dissolve anthraquinone and hydroanthraquinone (collectively referred to as working substances) in order to form a working solution. This working solution undergoes stages of hydrogenation, oxidation, and extraction throughout the production process; the raffinate from these stages is then returned to the hydrogenation stage for reuse. The properties of the solvent not only directly determine the production capacity of the plant, but also have a significant impact on the efficiency of hydrogenation, oxidation, and extraction processes, as well as on the degradation of effective anthraquinones. Given the characteristics of hydrogen peroxide production, an ideal solvent should meet the following requirements: 1) It should have good solvating capacity for both anthraquinone and hydroanthraquinone ； 2) Good chemical stability, especially excellent resistance to hydrogenation, oxidation, and hydrolysis ； 3) Low solubility in aqueous solutions of H2O and H2O2 ； 4) H2O2 has a high distribution coefficient between H2O and solvents, so there is no risk of explosion ； 5) It has a large density difference with water, facilitating separation ； 6) Low viscosity, low boiling point, low volatility, and high flash point ； 7) Low toxicity. Since it is difficult to meet all the above requirements using a single solvent, in order to achieve high solubility for both anthraquinone and hydroanthraquinone, mixed solvents consisting of a non-polar solvent (primarily used to dissolve anthraquinone) and a polar solvent (mainly used to dissolve hydroanthraquinone) are commonly employed in practical applications. 2.2.1 Current status of solvent use in the anthraquinone process: In industrial production, high-boiling heavy aromatic hydrocarbons with molecular weights of C9–C11 are commonly used as solvents for anthraquinone, while for hydrogenated anthraquinone, higher aliphatic alcohols and esters are utilized, such as trioctyl phosphate (TOP), diisobutyl methanol (DIBC), and methyl cyclohexanecarboxylate (MCA). Among them, diisobutylmethanol is characterized by very low water solubility and a high distribution coefficient, which facilitates the extraction process as well as the post-treatment of the extractant solution. Trioctyl phosphate and methyl cyclohexanecarboxylate are characterized by their ability to dissolve not only hydroanthraquinones but also anthraquinones effectively. The solvent systems currently used by major companies around the world are as follows. 1) FMC: Heavy aromatics + trioctyl phosphate (volume ratio of 75∶25); some new plants use tetrabutyl urea (TBU) in place of trioctyl phosphate (TOP) ； 2) Solvay Interox: Heavy aromatics + methyl cyclohexyl acetate (MCA) (volume ratio of approximately 1:1). The advantages of MCA are its high distribution coefficient for H2O2 and low viscosity; the disadvantages are its low solubility for hydroanthraquinone and low boiling point ； 3) MGC: Heavy aromatics + diisobutylmethanol (DIBC); moreover, DIBC has a low density (0.81 g/mL), which prevents the working fluid from having an excessively high density and facilitates extraction. 2.2.2 Nitrogen-containing polar solvents in the anthraquinone method: In order to be used in combination with common non-polar solvents such as benzene, alkylbenzenes, polyalkylbenzenes, alkyltoluenes, and alkynylbenzenes, polar solvents recommended in a number of European and American patents at the end of the 20th century were mostly nitrogen-containing polar solvents. Such as carbamamide derivatives and arylamide substitutes, their solubility in water at room temperature is less than 0.01, whereas anthraquinones and hydroanthraquinones have very high solubility in it. Moreover, amides with two aromatic groups generally have stronger antioxidant properties than those with only one aromatic group, while amides with one aromatic group have stronger antioxidant properties than those without any aromatic groups. For example, under the same conditions, N-ethyl-N-phenylacetamide has better antioxidant properties than N,N-diethylacetamide. There are also caprolactam derivatives in which the hexapropamide group is substituted with alkyl groups, such as octylcaprolactam and hexylcaprolactam; these have excellent solvating power for anthraquinones and hydroanthraquinones, and can be used as a single solvent or mixed with conventional anthraquinone solvents. Compared with previous nitrogen-containing solvents such as tetrasubstituted ureas and N-alkylsubstituted piperidines, it exhibits similar or higher solubility for anthraquinones and hydroanthraquinones, and also shows a significant improvement in the distribution coefficient, enabling the production of high-concentration hydrogen peroxide. Furthermore, the advantage of using alkyl-substituted ureas, such as tetraalkylureas, as solvents is their high solubility for hydroanthraquinone, which increases the hydrogen peroxide yield; they are also resistant to alkalis and high temperatures, allowing for long-term use. Furthermore, the high boiling point of tetraalkylureas facilitates the purification and dehydration of hydrogen peroxide, while their low density facilitates the extraction of hydrogen peroxide using water. N,N-diethyl-N′,N′-dibutylurea is one such solvent. In its patents, Degussa recommends using a mixed solvent composed of tetraalkylureas and trialkyl phosphates to dissolve hydroanthraquinone; this mixed solvent helps to avoid excessively high distribution coefficients, thereby enhancing operational safety ； High hydrogen peroxide production capacity and good selectivity in hydrogenation reactions ； The carbon content in hydrogen peroxide products has decreased, thereby improving the quality of these products. Like the substitutes of amides, aryl-substituted ureas can endow them with better antioxidant properties than conventional solvents. As recommended by Degussa for tetraalkylureas, if an aryl group is directly attached to the nitrogen atom, it can significantly enhance the antioxidant capacity of the tetraalkylurea. There are many aryl-substituted ureas suitable as solvents, among which the best ones are N, N-diisopropyl-N′-methyl-N′-phenylurea and N, N-dibutyl-N′-methyl-N′-phenylurea. Most of these nitrogen-containing polar solvents exhibit high solubility for hydrogen anthraquinone, and possess physical properties such as high boiling points, low density, low viscosity, and low water solubility. Working solutions composed of these solvents have a high capacity to produce hydrogen peroxide, but most of them are still in the research stage and have not been put into practical use yet. Finnish company Kemira has proposed an improved solvent: by adding a certain carbamate to the solvent system composed of heavy aromatics and trioctyl phosphate, it is possible to significantly increase the distribution coefficient of hydrogen peroxide between the working solution and water during the extraction process, thereby raising the concentration of the hydrogen peroxide solution obtained through extraction. A patent held by Akzo Nobel states that using a mixture of isodurene (1,2,3,5-tetramethylbenzene) and durene (1,2,4,5-tetramethylbenzene) as anthraquinone solvents, with a higher content of isodurene, can increase the solubility of anthraquinone. This reduces the proportion of anthraquinone solvent in the working solution while increasing the proportion of hydrogenated anthraquinone solvent, thereby enhancing the solubility of both anthraquinone and hydrogenated anthraquinone and improving the working solution’s ability to produce hydrogen peroxide. In recent years, the application of supercritical fluids has attracted widespread interest among scholars in the chemical industry. Replacing organic anthraquinone solvents with inexpensive, non-toxic, and non-flammable supercritical carbon dioxide can prevent contamination of hydrogen peroxide by organic solvents and eliminate the resistance to hydrogen diffusion into these organic solvents. It can also reduce the energy consumption associated with extracting hydrogen peroxide from organic solvents. Researchers at the University of Pittsburgh in the United States used supercritical CO2 as a solvent for dissolving anthraquinone compounds. Moreover, using CO2 as a solvent completely eliminated the influence of gas diffusion on the reactions during the hydrogenation and oxidation stages; at the same time, it reduced the content of organic carbon in H2O2, thereby improving product quality. 2.3. Anthraquinone hydrogenation process for producing hydrogen peroxide: The hydrogenation step in the anthraquinone method, as stated in the patents, involves heating using electromagnetic radiation (preferably microwaves), and the frequency of this electromagnetic radiation can be adjusted: 6.78MHz, 13.56MHz, 27.12MHz, 40.68MHz, 915MHz, 2450MHz. The most suitable frequencies are 915MHz and 2450MHz, at which their power levels range from 10W to 2000W. When heating is achieved using electromagnetic radiation, the hydrogenation process can take place in slurry reactors, fixed-bed reactors, fluidized-bed reactors, batch reactors, or continuous-flow reactors. The catalyst is palladium, rhodium, or nickel, and the carrier can be carbon, aluminum, or silicate. Microwaves are used because they enhance the hydrogenation of the working fluid ； Compared to existing processes, the rate of the hydrogenation reaction is significantly increased ； It reduces the amount of catalyst used, thereby lowering production costs ； Compared with traditional methods, the mass fraction of hydrogen peroxide obtained is as high as 48%. Large foreign producers of hydrogen peroxide, such as Akzo Nobel Eka, Degussa, Kemira, Solvay Interox, Atofina, and MGC, all have substantial production capacities for hydrogen peroxide. Each company has its own set of equipment, and these devices are located in many places around the world. Their hydrogenation processes also have their own distinct features. Akzo Nobel Eka has recently outlined the development process of the monolithic catalyst hydrogenation process, from its initial conception to industrial-scale application. This development work is primarily divided into two parts: the monolithic catalyst and the catalytic reactor, with the two being interrelated. The hydrogenation process employs a monolithic catalyst together with a corresponding reactor. The structure of this catalyst has been described earlier, and it is these characteristics of the catalyst that endow the reactor with numerous advantages: as the reaction stream passes through the catalytic bed, it comes into contact with the catalyst in each channel for the same duration, which prevents uneven reactions in certain areas and reduces degradation side reactions ； When the reactants pass through the catalytic bed, the bed resistance is low and the pressure drop is small, allowing for an increased feed rate. Additionally, thanks to the catalyst’s large geometric surface area and high catalytic activity, the production capacity of the plant can be significantly enhanced, with stability maintained over long-term operation ； No catalyst or special separation equipment is required, simplifying the process and making operation convenient. Degussa’s hydrogenation process uses tubular suspension hydrogenators, with the reactors consisting of a network of interconnected tubes; horizontal tubes and vertical tubes are connected by elbows, and each section of tube has the same outer diameter. There is a jacket outside the tube for heating and cooling; hydrogenation takes place within this reactor. The flow rate of the working fluid inside it is greater than 3 m/s, the operating temperature is around 100°C, and the absolute pressure is 15 bar. The catalyst is palladium black; before the working fluid and H2 enter the hydrogenator, they are premixed in a Venturi mixer, which significantly improves production capacity ； The catalyst flows continuously along with the working fluid; this working fluid reacts with hydrogen. After the reaction takes place in the reactor, it passes through a separator to achieve a preliminary separation of the catalyst from the hydrogenated fluid ； After separation, a dedicated hydrogenation fluid filter is required to separate the hydrogenation fluid from the catalyst once again. The filtration of the hydrogenation fluid containing catalyst must be carried out with great precision; otherwise, significant losses will occur and accidents are likely to happen ； The hydrogenation efficiency is 12 g/L. Kemira uses tubular hydrogenation reactors equipped with multiple static mixers made of inert materials; behind each mixer there is a catalyst section with a honeycomb structure, in which the catalytic substance palladium is loaded on the inner walls of its parallel channels (or the carrier is first loaded on those walls). The advantage of this hydrogenator is that during the hydrogenation process, the working fluid and hydrogen can be mixed thoroughly in a timely manner, thereby improving the efficiency of hydrogenation. Additionally, there are patents that suggest loading the catalyst directly on the baffle plates of a static mixer, thereby enabling mixing and reaction to occur simultaneously. There are also patents that provide fixed-bed hydrogenators with other structures. The hydrogenation processes at Solvay Interox, Atofina, and MGC utilize fluidized beds; to ensure the proper operation of these beds, catalysts in powder form are generally used. For example, Solvay Interox and Atofina employ a 2% Pd/Al2O3-SiO2-NaO2 catalyst in powder form ； The catalyst used by MGC is (0.5%～2%) Pd/Al2O3 ； Palladium black is also usually a good catalyst in fluidized bed reactors. Since these catalysts are in powder form, the small particles can effectively eliminate internal diffusion resistance and fully utilize the catalyst’s efficiency; as a result, such catalysts exhibit good dispersibility, activity, and selectivity. Therefore, the catalyst utilization rate is high throughout the hydrogenation process ； The hydrogenation yields are high; moreover, the large distribution coefficient of H2O2 during extraction results in a high concentration of the extracted product, with a mass fraction as high as 40% ； Quinone degradation is minimal. When the device starts operating, a small amount of catalyst is added at once; by adding it gradually, consumption is reduced and operating costs are lowered. Although the fixed-bed hydrogenation process is simple to operate and does not require catalyst separation, it has significant drawbacks, such as uneven reaction throughout the different sections, a tendency to form short circuits that lead to local hot spots, degradation of the working fluid, low catalyst utilization efficiency, and reaction rates affected by the diffusion of hydrogen. The hydrogenation efficiency of fixed-bed reactors, which are widely used in China (measured in terms of H2O2), is generally between 6 g/L and 7 g/L, whereas the efficiency of fluidized-bed reactors used abroad can exceed 18 g/L, indicating a significant difference. The use of a fluidized-bed process for the hydrogenation of anthraquinones in hydrogen peroxide production can **improve the efficiency of the plant, reduce the amount of catalyst and circulating working fluid required, and lower production costs.** At the same time, since the fluidized bed process ensures uniform hydrogenation of anthraquinone, it prevents the formation of local hot spots during the reaction, which could otherwise lead to degradation of the working solution; this helps to improve the quality of hydrogen peroxide products. Hydrogen peroxide is currently seeing an increasing use in industries such as chemical synthesis, electronic cleaning, and food disinfection, and its application in these fields imposes ever-higher requirements on the quality of hydrogen peroxide products. 3 Conclusion The industrial production of hydrogen peroxide primarily relies on the anthraquinone process, and research on this method has become increasingly sophisticated, with a large number of patents emerging internationally. In the production process using the anthraquinone method, the selection of catalysts, solvents, and the anthraquinone hydrogenation process is of utmost importance, and many researchers have conducted extensive work on this topic. The largest companies in the world that produce hydrogen peroxide have developed their own unique production technologies as well as corresponding manufacturing facilities. China has a high demand for hydrogen peroxide, yet the scale of its manufacturers is not large enough to meet this domestic demand; therefore, there is still significant potential for growth in the production of hydrogen peroxide in China. In the anthraquinone hydrogenation process used for hydrogen peroxide production, replacing the fixed-bed process with a fluidized-bed hydrogenation process will represent a breakthrough in this industry in China. The development of the fluidized-bed anthraquinone hydrogenation process will not only help boost the technical level, reduce production costs, and improve product quality in China’s hydrogen peroxide industry, which experiences strong demand growth, but it will also facilitate the wider use of hydrogen peroxide products in industries such as chemical synthesis, electronics, and food processing. References: Hu Changcheng. Recent Advances in the Research and Development of Hydrogen Peroxide Production Technologies Abroad. Chemical Industry Progress, 2003, 22(1): 29-33. DRACKETT THOMAS S. Electrolytic production of hydrogen peroxide using bipolar membranes. US: 5358609, 1994-10-25. CHUANG KARL T, ZHOU BING. Production of hydrogen peroxide. US: 5338531, 1994-08-16. BERTSCH-FRANK BIRGIT. Process for producing hydrogen peroxide by direct synthesis. US: 6387346, 2002-05-14. ISHII YASUTAKA. Process for producing hydrogen peroxide. US: 6375922, 2002-04-23. Chen Qunlai. Production and Applications of Hydrogen Peroxide in China. Modern Chemical Industry, 2001, 21(1): 11-14. Zhang JinSong, Zhou Yonghong. An Overview of Advances in Hydrogen Peroxide Production Technologies at Home and Abroad. China Nitrogen Fertilizer, 1996, 6: 9-12. BIANCHI DANIELE. Process for the preparation of hydrogen peroxide. EP: 0808796, 1997-11-26. STEPHENE JACOBSON. Preparation of hydrogen peroxide. US: 4711772, 1987-12-08. Wang Shengnian, Wang Shudong. Research Advances on Hydrogenation Catalysts for Hydrogen Peroxide Production via the Anthraquinone Process. Industrial Catalysis, 2000, 3(2): 11-14. LEE NATHAN D. Production of hydrogen peroxide in the anthraquinone process using a novel catalytic fixed bed. US: 3565581, 1971-02-23. IRANDOUST S. Monolithic catalyst reactor. Ind Eng Chem Res, 1989, 28: 1489. BENGTSSON ERIK A. Process for the production of hydrogen peroxide. US: 5063043, 1991-11-05. TAYLOR WILLIAM R. Decontamination apparatus. US: 5063043, 1991-11-05. PUKKINEN ARTO, HEIKKINEN LAURI. Hydrogenation catalyst for use in a hydrogen peroxide process and method for the preparation thereof. US: 5435985, 1995-07-25. FASMAN ANATOLIJ B, MAKSIMOVA NATALYA A. Catalyst for dehydration of anthraquinone. SU: 931221, 1982-05-30. GUILLET JAMES E, KOHLER KEVIN C. Aqueous phase production of hydrogen peroxide and catalysts for use therein. WO: 9705058, 1997-02-13. DEREMINCE VERONIQUE, VOGELS CLAUDE. Process for the manufacture of hydrogen peroxide. US: 5342603, 1994-08-30. Liu Jianxun, Wang Yaquan. Research Advances on Solvents for Hydrogen Peroxide Production via the Anthraquinone Process. Chemical Industry and Engineering, 2005, 22(1): 44-48. Editorial Committee of the Chemical Encyclopedia. Chemical Encyclopedia. Beijing: Chemical Industry Press, 1994. Fang Jing. An Overview of the Components of Carriers and Solvents Used in Hydrogen Peroxide Production via the Anthraquinone Process. Chemical Technology, 1998, 6(3): 18-23. Last edited by DAC Junlin Tianxia on 2007-7-16 21:14.]

Introduction to the Anthraquinone Process with Palladium Catalyst in a Fixed-Bed System for Hydrogen Peroxide Production 1. Overview The anthraquinone process using a palladium catalyst in a fixed-bed system for hydrogen peroxide production is the result of over 30 years of research and development by our institute; it won the Second Prize for Scientific and Technological Progress in 1985 and 1995 respectively. Our institute has transferred more than 40 sets of this technical equipment to domestic and international clients, including 3 sets exported to Indonesia. In China, our institute is the only entity that holds the intellectual property rights for the complete set of technologies related to hydrogen peroxide production using the anthraquinone method, a technology that enjoys a good reputation both domestically and internationally. Our institute possesses mature technology for this process; it features low energy consumption, and its production operations are safe, reliable, and simple. Comprehensive consideration has been given to unit operations, equipment, electrical systems, and control systems. It adopts a DCS control system, offering a high level of monitoring automation and requiring fewer operators. Among the technical units transferred by our institute, the production scale ranges from 10,000 tons/year to 150,000 tons/year (27.5% H2O2). Thanks to its technical advantages and excellent comprehensive technical support, our institute’s technology holds strong competitiveness both in China and in regions such as Southeast Asia, West Asia, and the Middle East. Hydrogen peroxide production is highly dangerous (flammable and explosive), and accidents can result in loss of life and property. In terms of safety assurance, our institute possesses extensive experience in processes, plant construction, and supporting services, enabling us to ensure that users receive high-quality, comprehensive service and safety protection, striving to perfect every aspect of the entire hydrogen peroxide production facility. In addition to possessing a complete set of hydrogen peroxide production technologies, our facility also has manufacturing equipment for key raw materials such as palladium catalysts, 2-ethylanthraquinone, solvents, and stabilizers, enabling us to supply users with high-quality products and raw materials. Our institute is able to provide comprehensive services to users in various aspects. In 2001, this project was listed by the **Economic and Trade Commission as a clean production project recommended nationwide. 2. Process Description 2.1 Overview The main stages of the process flow for this unit are as follows: (1) Production stage (01): Hydrogen peroxide solution is produced here. (2) Concentration section (02): Here, the hydrogen peroxide solution is concentrated in this production section. (3) Product storage and filling section (03): The hydrogen peroxide solution from the production section (01) and the concentration section (02) is stored in storage tanks, and then filled into containers or tank cars. (4) Wastewater treatment section (04): Treats the wastewater generated during the hydrogen peroxide production process. 2.2 Characteristics of the Equipment and Process 2.2.1 Characteristics of the Equipment The hydrogenation technology for producing hydrogen peroxide using palladium catalysts based on the anthraquinone process, provided by the Liming Chemical Research Institute to the buyer, is the result of over 30 years of research and development. Practical experience gained from factory operations has been continuously applied to the design of the industrial equipment, leading to continuous improvements and enhancements that have optimized both the process technology and the engineering design, bringing them to a level that is among the best in the world. This technical device has a low consumption rate, a short and rational process route, and is safe, simple, and reliable to operate. Strict safety measures are adopted in electrical engineering; electrical equipment and products from reputable manufacturers are selected, and all necessary equipment meets explosion-proof and fire-resistant requirements. 2.2.2 The main processes of this technology are as follows: ① Fixed-bed palladium catalyst hydrogenation process; ② Air oxidation in an empty tower; ③ Extraction process using a sieve tray tower along with product purification processes; ④ Use of trioctyl phosphate and aromatics as working solvents; ⑤ Treatment of wastewater generated during the production process of this unit using hydrogen peroxide. 2.2.3 Description of the palladium-catalyzed fixed-bed hydrogenation process: This process uses the anthraquinone auto-oxidation method to produce hydrogen peroxide. First, anthraquinone is mixed with a solvent to form a working solution; this solution then enters a hydrogenation reactor (a fixed-bed hydrogenation reactor), where it reacts with hydrogen in the presence of a catalyst to produce the corresponding hydrogen-anthraquinone compound. Subsequently, the working solution proceeds to the oxidation stage, where the hydrogen-anthraquinone compound reacts with air to produce oxygen, thereby being reduced back to anthraquinone and hydrogen peroxide being generated as a by-product. The resulting hydrogen peroxide is extracted using pure water and then purified to yield the diluted product. The extracted working solution is returned to the hydrogenation reactor to complete the cyclic production process.

Treatment of wastewater generated in hydrogen peroxide production: The production of hydrogen peroxide using the anthraquinone method involves the hydrogenation of alkyl anthraquinones dissolved in organic solvents in the presence of a catalyst, to yield the corresponding alkyl hydroanthraquinones. These are then oxidized; part of them is converted into H2O2 while the rest revert to alkyl anthraquinones. The H2O2 produced is extracted using pure water, thereby yielding the hydrogen peroxide product. The remaining alkyl anthraquinone solution is treated and then subjected to hydrogenation again, and this cycle repeats continuously. The main reactions of this method are as follows: The raw materials consumed in the aforementioned process are hydrogen, oxygen (which can come from air), and water; other raw materials are either lost due to mechanical reasons or are carried away with the product and waste materials, so they can be replenished periodically. 1 Sources of wastewater The wastewater generated in the production of hydrogen peroxide using the anthraquinone method consists of three main components. The first is the wash water from the working solution, with the main harmful substances being aromatics, 2-ethylanthraquinone, and trioctyl phosphate ； The second is the mixed wastewater generated during catalyst regeneration in the hydrogenation tower, which includes water vapor condensate and other substances, along with small amounts of the aforementioned three types of pollutants ； The third is the evaporation residue discharged from the concentration section. The daily wastewater discharge from the anthraquinone process hydrogen peroxide production plant, with a capacity of 40,000 t/a (based on 27.5% H2O2, the same applies hereafter), is 10–15 t. The wastewater is light orange in color, with a pH value of 5–7 and a COD level of 5000–7000 mg/L; it has a strong aromatic odor. 2 Wastewater treatment process 2.1 Process flow As shown in Figure 1, the chemical wastewater from the facility enters the wastewater tank, where it is pumped into a reaction vessel. A certain amount of ferrous sulfate and hydrogen peroxide are added to the vessel, followed by the addition of lime slurry, flocculants, etc. After precipitation and separation, the treated wastewater can be discharged, while the sludge can be used as backfill material after being filtered and dewatered. 2.2 Treatment Mechanism The mechanism for treating wastewater generated in hydrogen peroxide production using the catalytic oxidation-flocculation method involves adding hydrogen peroxide and divalent iron salts to the wastewater. Under acidic conditions, the divalent iron salts catalyze the decomposition of hydrogen peroxide, resulting in the formation of free radicals with strong oxidizing capabilities. These radicals can oxidize and remove minor pollutants present in the wastewater, such as certain aromatic compounds, trioctyl phosphate, and 2-ethylanthraquinone. Lime milk is then added to adjust the pH of the wastewater, causing the formation of Fe(OH)3 precipitates; flocculation and separation follow, thereby achieving wastewater purification.

The internationally popular method for producing hydrogen peroxide is the anthraquinone method, while the direct synthesis of hydrogen and oxygen represents the future direction of development. There have been reports on this in foreign countries, but few studies have been conducted in China. In China, the anthraquinone method mainly involves the use of palladium catalysts in fixed-bed systems; a few companies also use nickel catalysts, while only one company employs electrolytic methods. The anthraquinone method entails using alkylanthraquinones as carriers, with organic solvents as media, to produce hydrogen peroxide through processes such as hydrogenation, oxidation, extraction, and post-treatment. The key costs are cheap hydrogen and utility expenses (water, electricity, steam); generally, the cost of hydrogen is lower in the chlor-alkali industry and in industries that produce hydrogen from process gases.

Hydrogen peroxide technology exchange group 332059401

The environmental protection aspect related to hydrogen peroxide requires further advancement in the technology for recovering heavy aromatic hydrocarbons from oxidation exhaust gases. Currently, the consumption levels of heavy aromatics, which serve as important solvent working fluids in hydrogen peroxide production, vary across China; the amount of heavy aromatics used per ton of hydrogen peroxide ranges from 18 kg to 2 kg. These are all caused by the following reasons: First, the process design institute for hydrogen peroxide production lacks knowledge and understanding of multi-aromatic hydrocarbon recovery technologies. Second, current recovery methods for heavy aromatics are all based on technologies introduced in the 1980s; no new technologies have emerged to date, and there is a lack of technological updates. Third, regulations on organic gas emissions were quite lax at the time; enterprises lacked awareness and motivation, and there was also a lack of technical research and expertise in this area within related research fields. Fourth, supervision of the environmental industry is lax; environmental impact assessments have become a mere formality for accepting bribes, resulting in no progress in work. At present, with a clear emphasis on strengthening environmental protection, Beijing can serve as a leader in advancing technological innovation in this field. Various organic gas recovery processes have been developed for dealing with complex pollutants used in industries such as hydrogen peroxide production, the petrochemical sector, oil processing, nitric acid manufacturing, and pharmaceuticals. The efficiency of these recovery processes is far superior to that of the recovery equipment currently available on the market. It is hoped that through gradual adoption, environmental protection can be transformed into a truly robust high-tech industry. The company argues that before the emergence of this technology, environmental protection required companies to pay a high price; \"environmental protection metrics equaled negative economic metrics,\" which meant companies had limited resources. Through technological innovation, companies can reduce their costs by recycling emissions; thus, \"environmental indicators equal positive economic indicators,\" which gives companies the motivation to make improvements.

Hydrogen peroxide industry group: 51628245

We have just received funding from the US National Science Foundation for research on the efficient and energy-saving concentration of dilute hydrogen peroxide solutions. The process used for concentrating hydrogen peroxide is membrane-assisted multi-stage multi-effect evaporation, which is an exclusive technology of our company. This process combines the selectivity of membranes with the high thermal energy efficiency of multi-stage multi-effect evaporation, achieving twice the result with half the effort. The operating conditions of this process are extremely mild; there is no high temperature, high pressure, or vacuum involved, and there is almost no noise at all. The operating temperature is generally between 40 and 80 degrees, which allows for the full utilization of waste heat at low temperatures while preventing the thermal decomposition of hydrogen peroxide. The materials used for membranes and membrane equipment are all functional plastics, which are resistant to oxidation and corrosion, resulting in low investment costs. Removing one ton of water from a dilute hydrogen peroxide solution requires 0 of atmospheric pressure steam. 12 - 0. 30 tons (depending on the water concentration in the feed solution), which is far better than the distillation process; it is even 30-60% more energy-efficient than conventional multi-effect evaporation. It is reiterated that this process can use steam at normal or negative pressure, as well as hot water at 60–120 degrees or flue gas as a heat source. We are looking for hydrogen peroxide manufacturers or users in China to carry out a demonstration project for hydrogen peroxide concentration. For interest, please contact: yjqin1@yahoo.com or yqin@chembrane.com or 001 - 973 988 1979 (USA)