Ethyl acetate production technology and market

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Production Technology and Market of Ethyl Acetate 1. Overview Ethyl acetate (EA) is an important downstream product of acetic acid, as well as a significant green organic solvent. It boasts excellent solvating power and fast-drying properties, and is primarily used as an active solvent in formulations for coatings (paints and varnishes), inks, and adhesives. It can also be employed as a process solvent in pharmaceuticals and organic chemical synthesis. Furthermore, since EA is a natural compound found in many fruits, it has wide applications in the food industry, where it can be used as a flavoring agent and a processing extractant. According to statistics, in 2004, 60% of EA’s consumption was used for coatings, 15% for printing inks, and 10% for adhesives and similar applications. Due to EA replacing the environment-polluting methylethyl ketone and methyl isobutyl ketone in the fields of surface coatings and ink formulations, it has great development potential. 2. Industrial production technologies: Currently, the main global industrial production methods for EA include acetate esterification, acetal synthesis, ethanol dehydrogenation, and ethylene addition. The traditional acetate esterification process is being phased out abroad, while large-scale production facilities mainly use the latter three methods, among which the ethylene addition method is commonly adopted in newly built facilities. 2.1 Acetate esterification: Under the action of a sulfuric acid catalyst, acetic acid and ethanol are directly esterified to produce EA. This method features mature process technology, low investment, and simple operation, but its disadvantages include high production costs, strong corrosivity of sulfuric acid on equipment, numerous side reactions, difficulty in product treatment, and severe environmental pollution. At present, most enterprises in our country still use the acetate esterification method to produce EA. 2.2 Acetaldehyde condensation method: Under the action of the catalyst aluminum ethoxide, acetaldehyde undergoes auto-oxidation, condensation, and rearrangement to form EA. The advantages of this method are relatively mild process conditions, high reaction conversion and yield, low requirements for equipment, and lower production costs compared to the acetate esterification method. The disadvantages are limited sources of raw materials, and the catalyst aluminum ethoxide cannot be recovered as it is discharged as aluminum hydroxide upon addition of water. The acetaldehyde condensation method was once a production technique actively recommended in China; this technology is well-developed abroad, especially in Japan. China achieved industrial production on a scale of tens of thousands of tons in the 1990s. The drawback of this method is that it is only competitive when the price of acetaldehyde is low. 2.3 Ethanol Dehydrogenation Method The ethanol dehydrogenation method is a process technology that was successfully developed by Davy Company in 2001. This method uses only ethanol as a raw material and a copper-chromium oxide catalyst; ethanol is dehydrogenated to produce acetaldehyde, which then reacts with ethanol to form crude EA. The acetaldehyde and other carbonyl compounds present in crude EA are hydrogenated before product distillation to yield the corresponding alcohols, while ethanol is recycled back to the dehydrogenation reactor. Then, another specialized catalyst is used, and the azeotrope is removed through high and low pressure distillation to obtain EA with a purity of over 99.8%. This process is operated at moderate pressure and temperatures below 200°C. This process is suitable for areas with abundant and inexpensive ethanol. This process was first industrially applied in 2001 at a 50,000 t/a plant at Sasol in South Africa. Davy Company is currently continuing to screen catalysts for this process, with the goals of improving conversion rates, extending catalyst life, and reducing production costs. At the same time, this technology is also being promoted in North Africa, South Africa, and Southeast Asia, where sources of low-cost ethanol are available. 2.4 Ethylene addition method: This is a production method that directly produces EA using ethylene and acetic acid as raw materials. Under the catalysis of metal salts of heteropolyacids or heteropolyacids loaded on carriers such as silica, ethylene is hydrated in the gas phase and then directly esterified with vaporized acetic acid to produce EA. Companies such as BP/Amoco, Rhone-Poulenc, and Showa Denko have all developed this process. The representative BP “Avada” process uses heteropolyacid catalysts, which exhibit high catalytic activity and selectivity, enabling the product purity to reach over 99.97%. It is claimed that compared to traditional esterification or condensation EA routes, the “Avada” process offers the following advantages: high yield, 35% less raw material loss, and 20% lower energy consumption. This process improves the production steps and facilitates the capacity expansion of the equipment. 3 Technical Progress Currently, the main new process developed is the one-step synthesis of EA using ethanol; other advancements involve improvements to traditional processes and catalysts, as well as research on co-production technologies. 3.1 Development of the process for synthesizing EA from ethanol in one step and the catalysts involved: Taiwan’s China National Petroleum Corporation developed a process for synthesizing EA from ethanol in a single step. This process involves the partial oxidation of ethanol to produce acetic acid, which is then esterified with excess ethanol to yield EA. A trickle-bed reactor filled with an oxidation catalyst (containing 10% Pd) and an esterification catalyst (solid ion-exchange catalyst) was used. Liquid ethanol and oxygen were fed at 3.59 MPa and a space-time velocity of 2.4 h-1; they first passed through a static mixer before entering the top of the reactor, where the reactants flowed downward through the catalysts located in the layer of glass beads. At 95°C, 93.5% of the aqueous ethanol was converted, with selectivities of 68.5%, 30.6%, and 0.9% for EA, acetic acid, and acetaldehyde, respectively. Shōwa Denko has also developed a catalyst for the one-step synthesis of EA from ethanol, which can increase the space-time yield of the product and reduce the selectivity of by-products. At a temperature of 160°C, a pressure of 0.8 MPa, an ethanol/oxygen ratio of 5/3 (mol), and a space velocity of 1800 h-1, this catalyst achieved an ethanol conversion rate of 75%, an EA selectivity of 80%, and an EA space-time yield of 212 g/h·Lcat. The acetic acid selectivity was 12%, while the selectivities for the by-products CO2 and acetaldehyde were 2.3% and 2.8%, respectively. The advantage of this process is that it uses a single reactor to convert ethanol into EA, which minimizes the investment costs. 3.2 Development of catalysts for the ethanol dehydration process: Nippon Nitto Petrochemical Corporation developed a highly active and selective Cu-Zn-Zr-Al-O catalyst by adding various metal oxides to the core of a copper-based catalyst. This catalyst, when used at 220°C and 1 MPa, achieved an ethanol conversion rate of 45.2% and an EA selectivity of 95.6%. Compared with the catalyst developed by Davy Company (which achieved an ethanol conversion rate of 28% and an EA selectivity of 95% at 2.8 MPa and 223°C), the conversion rate was significantly improved while maintaining a similar selectivity. 3.3 Improvements in impurity separation technology in EA: BP/Amoco separated the acetic acid/ethylene addition product by distillation in a distillation column; the bottom fraction of this column was EA, while the top fraction was a mixture of ether and acetaldehyde. This top fraction was then fed into an acetaldehyde removal column, where acetaldehyde was removed from it. Since the boiling points of ethanol and EA are very close, it is not possible to remove ethanol from EA using conventional distillation or rectification. Researchers found that by adding substances such as ether and cyclohexane to the crude EA to form an azeotropic liquid, EA can be easily separated ； Ethanol in the crude EA can also be removed through extractive distillation by adding solvents such as amines and paraffin to the crude EA. 3.4 Coupled Production Technology: BP/Amoco developed a process for the oxidation of ethane to produce ethylene and acetic acid. In the oxidation reaction zone, there are at least two catalysts with different selectivities; ethane (preferably containing ethylene), oxygen-containing gases, and water react to yield ethylene and acetic acid. The molar ratio of ethylene to acetic acid in the products can be determined by controlling the ratio of the different catalysts. This process can be used in combination with BP/Amoco’s ethylene addition EA process, thereby reducing raw material costs. Furthermore, the process developed by Solutia Company can produce EA as a by-product during the production of polyvinyl alcohol, which is used to manufacture polyvinyl butyral. 4 Domestic and International Market Analysis: In 2004, the global total production capacity for EA was approximately 1.41 million tons per year (excluding China), with production and consumption mainly concentrated in Western Europe, the United States, and Asia. Abroad, EA is mainly used in coatings and various solvents, with coatings accounting for 60% of its applications ； Including pharmaceuticals and process solvents for organic synthesis accounts for 15% ； Printing ink accounts for 15% ； Others, including adhesives and cosmetics, account for 10%. Since EA can replace harmful solvents such as methanol and ethanol, which volatilize into the air, global consumption of EA is expected to increase rapidly by 2008. Experts note that in recent years, the EA industry has shown the following development trends: first, a high degree of concentration in production, as the top 6 manufacturers such as BP and Nippon Showa account for approximately 70% of the world’s total production capacity ； Secondly, the plants are becoming increasingly large in scale; most plants abroad have an annual production capacity of over 50,000 t/a. The \"Avada\" process used in Hull, UK, has enabled the construction of the world’s largest EA plant with a capacity of 220,000 t/a. Thirdly, there is rapid growth in the construction of such plants – in recent years, BP in Western Europe and Indonesia, as well as Showa Denko in Singapore and Indonesia, have all built large-scale plants. At present, there are over 30 EA manufacturers in our country; among them, 15 have a production capacity of 10,000 tons or more, while the remaining facilities have smaller scales and are either shut down or operating at reduced capacity. The industrial production of acetates in our country relies primarily on the esterification method. As of February 2006, China’s total EA production capacity had reached approximately 790,000 tons per year. The main manufacturers included Jiangsu Supor Group (200,000 tons per year, including 150,000 tons per year that came online in January 2006), Shandong JinYimeng Group (160,000 tons per year), Yangtze River Acetyl Chemical Company (80,000 tons per year), Jiangxi Nanchang Ganjiang Solvent Factory (80,000 tons per year), Jiangmen Qianxin Chemical Development Company (35,000 tons per year), Shanghai Wujing Chemical Company (50,000 tons per year), Shanghai Reagent Co., Ltd. Organic Chemical Plant (20,000 tons per year), Shanghai Petrochemical Corporation (20,000 tons per year), Guangdong Shunde Gas Solvent Factory (15,000 tons per year), and Tianjin Guanda Industrial Group Organic Chemical Plant (10,000 tons per year). With the rapid development of China’s chemical, pharmaceutical, and automotive industries, the consumption of EA has increased steadily. Between 1997 and 2002, the apparent consumption growth rate of EA in China reached 26.4%, requiring large amounts of EA to be imported each year to cover the shortfall. However, as new production capacity came online domestically, underutilization of capacity has occurred in recent years, leading to a continuous decline in imports, which dropped from 53,500 tons in 2001 to 34,600 tons in 2004. There was a rebound in 2005, with imports rising to 46,400 tons. At the same time, exports increased from 21,000 tons in 2004 to 188,000 tons. The domestic market is currently saturated, with an oversupply situation, leading to a downward trend in product prices. In our country, EA is used in large quantities in industries such as the chemical industry and the pharmaceutical industry; 40% of its consumption is in the chemical industry, 35% in the pharmaceutical industry, and 25% in other sectors. In recent years, with the rapid development of the coating industry in our country, many well-known foreign coating manufacturers have established factories here to produce high-quality coatings through wholly-owned or joint ventures. As a result, the demand for high-quality coatings is increasing, and the proportion of EA consumption in this area will rise further. Additionally, with the swift growth of industries such as packaging and electronic information, it is expected that the demand for EA in the ink industry will increase at a fast pace in the future. At present, some large domestic enterprises that produce acetic acid via methanol carbonylation are constructing or planning to build EA units; among them is Shandong Haihua Co., Ltd., which is designing a facility with an annual production capacity of 100,000 tons (using Davy technology, with commissioning scheduled for 2007) ； Jihua Group (50,000 t/a, using Davy technology); Liaoyuan in Jilin is seeking investment for a plant with a capacity of 50,000 t/a (using the esterification method) ； Taixing Investment Promotion in Jiangsu Province plans to build a plant with a capacity of 100,000 t/a (using the esterification method) ； 50,000 t/a in Songyuan, Jilin; Shandong Lunan Fertilizer Factory plans to build a plant with a capacity of 80,000 t/a ； Sinopec and BP plan to jointly build a facility with a capacity of 150,000 t/a, etc. If these projects are implemented, China’s total EA production capacity will exceed 1.2 million t/a by 2010. In terms of technology, some institutions in our country have also carried out research and development on EA processes: for example, Tsinghua University has developed an improved green and energy-saving esterification method, namely a combined technique of esterification catalyzed by non-polymeric solid acids and salt extraction distillation. Compared with traditional esterification methods, this approach can reduce energy consumption by 20%–25%, lower raw material usage by 5%, save 200 RMB per ton in total production costs, reduce investment expenses by 30%, and significantly improve product quality. The EA synthesis energy-saving technology developed by South China University of Technology effectively removes the water generated during EA synthesis as well as the water contained in the raw materials from the reaction system, thereby significantly reducing the reflux ratio in the esterification process. This leads to a substantial reduction in energy consumption compared to traditional methods and a significant increase in production capacity. This technology can be applied to modify existing facilities, requiring few modifications and minimizing the amount of work needed for such adjustments. In addition, the Guangxi Chemical Industry Research Institute synthesized EA using alcohol and glacial acetic acid as raw materials, along with a solid acid catalyst, through a continuous catalytic distillation-extraction process. Compared with traditional esterification processes, this process features high equipment production capacity and low energy consumption ； China National Petroleum Corporation has also developed a one-step ethanol production process, while the Petrochemical Research Institute of Heilongjiang Academy of Sciences and the R&D institute of Sinopec Nanjing Chemical Co., Ltd. have developed an acetaldehyde condensation process. 5 Recommendations: (1) At present, the EA market in our country is facing a surplus of supply; under such circumstances, the construction of new EA facilities should be carefully evaluated. (2) In the past two years, the construction of EA plants in China has tended to move towards larger scales; for example, Jiangsu Sopu’s plant has a capacity of 150,000 t/a, Shandong JinYimeng’s plant has a capacity of 160,000 t/a, and Shandong Haihua is building a plant with a capacity of 100,000 t/a. It can be said that China’s EA industry has reached a considerable scale, but the vast majority of these plants still have small capacities, produce low-quality products, and consume high amounts of raw materials. Domestic enterprises should accelerate technological upgrades and equipment modernization in the future to improve product quality and reduce costs. Currently, acetic acid used as a raw material for production abroad is generally synthesized through the methanol carbonylation process on a large scale, resulting in lower EA costs compared to those in China. Therefore, domestic manufacturers that use the methanol carbonylation method should be able to achieve economic viability if they also install equipment for the acetic esterification process. (3) The acetaldehyde condensation method was once a production approach actively recommended in China; however, with the domestic price of acetaldehyde currently around 4,700 yuan per ton, it is no longer economical to use this method for production under such conditions. Furthermore, the adoption of advanced carbonylation methanol processes in acetic acid production in recent years has led to a continuous decline in the global market size for acetaldehyde. North America has completely stopped producing acetaldehyde, and most acetaldehyde production facilities in Europe have also ceased operations; it is expected that global demand for acetaldehyde will continue to decrease over time. Therefore, the future prospects for the acetal condensation process are not optimistic. (4) The ethanol dehydrogenation process developed by the UK-based KPT company uses only ethanol as raw material, making it highly suitable for use in combination with low-cost ethanol fermentation facilities. Therefore, it is competitive to build production plants using this process in regions of China where there is an excess of ethanol.