Production, applications, and market analysis of acetic acid at home and abroad

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Production, Applications, and Market Analysis of Acetic Acid at Home and Abroad by Shen Juhua (Sinopec Shanghai Research Institute of Petrochemicals, 201208) Abstract: A review is provided on the development trends in acetic acid production technologies as well as market supply and demand both domestically and internationally. It is believed that acetic acid, as one of the important organic raw materials, has promising prospects for development in China. By drawing on foreign development strategies, outdated processes including the ethylene-acetaldehyde method should be phased out, and advanced methanol carbonylation processes should be developed. At the same time, attention should be paid to scale effects; it is advisable to build plants with a capacity of 300–500 kt/a in areas where the conditions permit. Keywords: Acetic acid, process, progress, market. Acetic acid is an important organic chemical raw material, mainly used in the production of vinyl acetate monomer, acetic anhydride, polyethylene terephthalate (PTA), polyvinyl alcohol, acetates, cellulose acetate, and other products. It has a wide range of applications in industries such as chemicals, textiles, pharmaceuticals, and dyes. In recent years, the development of downstream products derived from PTA and acetic acid has made acetic acid one of the few petrochemical products whose production capacity and demand are growing rapidly. 1 Current Status and Development Trends of Production Technologies 1.1 Current Status of Production Technologies Looking at the history of the acetic acid industry, the world’s first industrial plant for synthesizing acetic acid through the oxidation of acetaldehyde was built and put into operation in Germany in 1911. In 1960, the high-pressure, high-temperature methanol carbonylation process for acetic acid production, which uses methanol as a raw material and cobalt as a catalyst and was developed by the German company BASF, was put into industrial use. In 1983, the American company Eastman built an industrial facility for the co-production of acetic acid and acetic anhydride. In recent years, processes such as traditional methanol carbonylation have been continuously improved, with new processes and technologies emerging one after another, thereby driving continuous advancements in acetic acid production technology. Currently, the main production processes in the international acetic acid industry include the methanol carbonylation method, the acetaldehyde oxidation method, and the liquid-phase oxidation of butane (light oil). In terms of production capacity, approximately 60% uses the methanol carbonylation method, 18% uses the ethylene acetaldehyde oxidation method, 10% uses the ethanol acetaldehyde oxidation method, 8% uses the butane/naphtha oxidation method, and 4% uses other methods. 1.1.1 Methanol carbonylation method: The typical production processes in the methanol carbonylation synthesis method are Monsanto/BP and Halcon/Eastman. The former uses a rhodium catalyst, while the latter employs a non-precious metal catalyst system, namely a nickel acetate/methyl iodide/tetraphenyltin catalyst system. In recent years, two new processes have emerged: Celanese’s AO Plus process (acid optimization process) and BP Chemicals’ Cativa process based on iridium catalysts. 1.1.2 Ethylene oxidation method: This method can be divided into indirect and direct approaches. The indirect approach is the ethylene-acetaldehyde oxidation method, which saw rapid development in the 1960s. However, with the advancement of Monsanto’s methanol carbonylation process, the use of the ethylene-acetaldehyde method gradually declined, as it was inferior to the methanol carbonylation process in terms of various technical and economic criteria. At present, this process remains the main method for producing acetic acid in China. This process uses acetaldehyde as the raw material, and liquid-phase catalysts such as manganese acetate, cobalt acetate, or copper acetate are employed for the oxidation reaction at temperatures of 50–80 °C and pressures of 0.6–0.8 MPa. The conversion rate of acetaldehyde is over 90%, while the selectivity for acetic acid is higher than 95%. All equipment used in the process must be made of stainless steel. In 1997, Showa Denko in Japan built an acetic acid plant with a production capacity of 100 kt/a at its Chiba facility, using a direct process for acetic acid production that does not involve acetaldehyde. This plant employs a new palladium-based catalyst; the reaction takes place in a fixed-bed reactor at a temperature of around 150–160 °C and a pressure of about 0.9 MPa. The one-pass conversion rate of ethylene is 7.4%, while the selectivities for acetic acid, acetaldehyde, and CO2 are 86.4%, 8.1%, and 5.1%, respectively. Compared with methanol and acetaldehyde process plants of similar scale, the construction cost of direct oxidation process plants is significantly lower, and the plant size can be designed according to the user’s requirements. Furthermore, this process is very simple, and the amount of wastewater discharged is significantly reduced, to only one-tenth that of the acetaldehyde oxidation method. 1.1.3 Butane oxidation method: The two processes using n-butane or light oil as raw materials are essentially similar. Using light oil in the C5–C7 range as a raw material, and with catalysts such as cobalt acetate, chromium acetate, vanadium acetate, or manganese acetate, the reaction is carried out at temperatures of 170–200 °C and pressures of 1.0–5.0 MPa. The final products are formic acid, propionic acid, and acetic acid, in a ratio of acetic acid:formic acid:propionic acid of 1:0.25:0.10. Furthermore, the ethanol-acetaldehyde oxidation method mainly includes two processes: the oxidation dehydrogenation of ethanol to acetaldehyde, and the oxidation of acetaldehyde to acetic acid. Currently, some developing countries **still use this production technology, but due to poor technical and economic indicators, most of them have ceased or partially ceased operations. 1.2 Trends in Technical Development Recent significant developments in acetic acid production technology include the Chiyoda \"Acetica\" process in Japan, which uses supported catalysts; the Hoechst and SABIC processes based on ethane; as well as various acetic acid processes based on syngas. 1.2.1 Methanol carbonylation process: The acetic acid production technology \"Acetica\" developed by Chiyoda Corporation in Japan utilizes a solid-supported heterogeneous catalyst system and a bubble column reactor. Compared with traditional homogeneous methanol carbonylation processes, the rhodium catalyst is immobilized on a polyvinylpyridine resin phase complex, thereby overcoming the loss of the expensive precious metal rhodium. This process also uses rhodium complexed with polyvinylpyridine resin as a catalyst, and methyl iodide as a co-catalyst. It is reported that, on a methanol basis, the yield of acetic acid is greater than 99%, and on a CO basis, the yield of acetic acid is greater than 92%. 1.2.2 Ethane synthesis process: The process developed by Union Carbide in the 1980s for the catalytic oxidation of a mixture of ethane and ethylene to produce acetic acid (the “Ethoxene” process) features high selectivity; its main characteristic is that, in addition to acetic acid, it also produces large amounts of ethylene as a by-product. Sabic has developed its proprietary technology for the catalytic oxidation of ethane to acetic acid, which involves the reaction of ethane with pure oxygen or air at temperatures of 150–450°C and pressures of 0.102–5.1 MPa to produce acetic acid. The catalyst system was prepared by calcining a mixture of oxides of Mo, V, Nb, and Pd, achieving an acetic acid selectivity of 71%. Due to the low cost of ethane in this process, its production economics can compete with those of the methanol carbonylation technology. The Sabic acetic acid technology package includes a set of catalysts for industrial-scale plants, a new design for oxidation reactors, an integrated process flow, and the design of basic infrastructure. Sabic has constructed a 30 kt/a acetic acid production facility in the Ibn Rushd area of Yanbu, Saudi Arabia, which is expected to come online by the end of 2003. Sabic will continue to improve this technology to enhance its performance, aiming to achieve world-scale production and considering building a plant with a capacity of 200 kt/a. 1.2.3 Process for producing acetic acid from syngas: Union Carbide has revealed that a single reactor together with a multi-component catalyst system can be used to convert syngas into acetic acid. This multi-component catalyst includes a synthetic methanol catalyst and a methanol carbonylation catalyst. These catalysts can be used in separate reaction beds or as a mixture of the two catalysts. Synthetic methanol catalysts are metal-based solid catalysts, such as Cu/ZnO, copper-ferroalloy materials, and supported metals from groups VII, VIII, and the halogen groups of the periodic table. Methanol carbonylation catalysts are solid superacids, heteropoly acids, clays, zeolites, molecular sieves, and other similar substances. This catalyst system itself has two important features: it does not require halides ； The presence of hydrogen in the methanol carbonylation reaction can enhance and extend catalyst activity and lifetime ； Avoiding the use of iodomethane (MeI) can save some costs in terms of process design, equipment materials, and product purification. 2 Technical and economic comparison of several process routes ChemSystems conducted a technical and economic comparison of acetic acid production processes using three different raw material routes; details are shown in Table 1. Table 1 Comparison of Economic Indicators for Acetic Acid Production Routes Using Three Different Raw Materials
| Process | Ethane Direct Oxidation | Ethylene Direct Oxidation | Methanol Carboxylation – Hoechst Process | Methanol Carboxylation – Showa Denko Process | Traditional BP Process | Celanese AO Process | BP Amoco Cativa Process |
|---------|------------------------|--------------------------|-------------------------------------------|--------------------------------------------|----------------------|--------------------|--------------------------|
| Plant Capacity / kt·a⁻¹ | 200 | 200 | 200 | 500 | 500 | — | — |
| Total Investment / million USD | 166.1 | 124.1 | 130.4 | 116.7 | 145.2 | 116.7 | 145.2 |
| Investment within the plant boundary / million USD | 117.6 | 91.9 | 103.1 | 66.4 | 94.9 | 66.4 | 94.9 |
| Investment outside the plant boundary / million USD | 48.5 | 32.2 | 27.3 | 50.3 | 50.3 | 50.3 | 50.3 |
| Production Cost / USD·kg⁻¹ | 0.346 | 0.528 | 0.394 | 0.297 | 0.310 | 0.242 | 0.451 |
| Cash Cost / USD·kg⁻¹ | 0.242 | 0.451 | 0.317 | 0.268 | 0.275 | 0.242 | 0.451 |
| Variable Cost / USD·kg⁻¹ | 0.183 | 0.383 | 0.266 | 0.251 | 0.255 | 0.183 | 0.383 |
| Net Raw Material Cost / USD·kg⁻¹ | 0.187 | 0.348 | 0.238 | 0.231 | 0.233 | 0.187 | 0.348 |
| Net Utility Cost (0.004) / USD·kg⁻¹ | 0.035 | 0.029 | 0.020 | 0.022 | — | — | — |
| Direct Fixed Cost / USD·kg⁻¹ | 0.029 | 0.035 | 0.024 | 0.009 | 0.011 | 0.029 | 0.035 |
| Indirect Fixed Cost / USD·kg⁻¹ | 0.031 | 0.033 | 0.024 | 0.009 | 0.011 | 0.031 | 0.033 |
| Depreciation / USD·kg⁻¹ | 0.103 | 0.077 | 0.079 | 0.029 | 0.035 | 0.103 | 0.077 |
| 10% Return on Investment (ROI) / USD·kg⁻¹ | 0.103 | 0.077 | 0.079 | 0.029 | 0.035 | 0.103 | 0.077 |
| Total Production Cost (Production Cost + 10% ROI) / USD·kg⁻¹ | 0.449 | 0.605 | 0.473 | 0.326 | 0.345 | 0.449 | 0.605 |

As can be seen from Table 1: (1) The newly developed Celanese AO process and BP Amoco Cativa process, thanks to their relatively advanced technology, enable newly built or upgraded acetic acid plants to have a capacity of over 500 kt/a. This results in significantly lower investment costs and production costs. The investment cost for a 500 kt/a Celanese plant is 116.7 million USD, which is even lower than that of a plant using the ethane direct oxidation method with a capacity of 200 kt/a. The total production cost for this process is 0.326 USD/kg, the lowest among all processes. (2) The direct oxidation of ethylene process developed by Showa Denko in Japan has an investment cost of $124.1 million at a scale of 200 kt/a, which is lower than that of the traditional BP-Monsanto process; it is $42 million and $63 million lower respectively than the direct oxidation of ethane and the traditional BP-Monsanto process. However, its production cost of $0.605 per kg is $0.132 per kg higher than that of the traditional BP-Monsanto process, due to the relatively high price of ethylene as a raw material. Although it has an advantage over the traditional ethylene-acetaldehyde oxidation process in terms of production costs, it does not have a significant advantage over the methanol carbonylation process or the ethane oxidation process. (3) Compared with the direct oxidation of ethylene and the conventional BP-Monsanto process, the direct oxidation of ethane has a certain advantage in terms of production costs due to the relatively low price of its raw materials. The total production cost is $0.449, which is $0.156/kg and $0.224/kg lower than that of the direct oxidation of ethylene, respectively. This is highly beneficial for regions rich in ethane resources such as the Middle East. 3 Forecast of supply and demand in foreign markets: According to statistics, in 2002, the global capacity, production, and consumption of acetic acid were 8,764 kt, 6,850 kt, and 6,850 kt respectively. The supply and demand situations in the main regions, as well as the distribution of uses, are shown in Table 2 and Table 3 respectively. Driven by the development of downstream products derived from PTA and acetic acid, global acetic acid production capacity is expected to reach 10,648 kt/a in 2007 and 11,018 kt/a in 2010, while corresponding production volumes are projected to reach 8,320 kt and 9,055 kt respectively during the same period. Table 2: Global and major regional capacities, production, and consumption of acetic acid in 2002, in kt
Region: Capacity/kt·a-1; Production; Consumption
North America: 2,730; 2,503; 2,187
South America: 482.7; 150
Western Europe: 1,445; 1,130; 1,260
Eastern Europe and Russia: 537; 2,031; 788
Middle East and Africa: 582; 249
South Asia and Southeast Asia: 1,300; 1,000; 629
East Asia: 1,829; 1,350; 1,793
Japan: 817; 615; 603
Global total: 8,764; 6,850; 6,850

Table 3: Distribution of uses for acetic acid globally and in major regions in 2002, in kt
Region: Acetates; Acetic anhydride; Solvents; PTA; Others; Total
North America: 1,142; 489; 1,231; 1,802; 542; 2,188
South America: 400; 671; 1,321; 1,500
Western Europe: 533; 300; 266; 976; 412; 2,600
Eastern Europe and Russia: 330; 105; 040; 178
Middle East and Africa: 130; 101; 794; 9
South Asia and Southeast Asia: 1,420; 106; 2,381; 436; 2,900
East Asia: 852; 342; 3,448; 019; 617; 1,793
Japan: 433; 254; 571; 296; 03
Global total: 3,187; 848; 953; 109; 576; 850

4. Forecast of supply and demand in the domestic market
Acetic acid production in China began in 1953. By 2002, the actual production capacity for acetic acid had reached 1,115 kt/a, with a production volume of 841 kt/a. Among them, the methanol carbonylation process has a production capacity of 420 kt/a, accounting for 37.7% of the total production capacity. The ethylene oxidation method accounts for 458 kt/a, representing 41.0% of the total production capacity. The ethanol-acetaldehyde method accounts for 237 kt/a, representing 21.3% of the total production capacity; there are over 50 manufacturers, of which more than 10 have a production capacity of 10 kt/a or more. In 2002, the operational rates of the methanol carbonylation method, the ethylene acetaldehyde method, and the ethanol acetaldehyde method were 94.8%, 91.3%, and 20.7% respectively. The production capacity and output of the major manufacturers in 2002 are shown in Table 4. Table 4: Production capacity and output of major acetic acid manufacturers in China
Manufacturer | Production capacity/kt·a-1 | Output/kt | Production process
Jihua Group Company | 210 | 175.75 | Ethylene oxidation method
Yangtze River Acetate Company | 200 | 183.89 | Methanol carbonylation method
Shanghai Pacific (Group) Company | 100 | 142.01 | Methanol carbonylation method
Jiangsu Supor Group Co., Ltd. | 120 | 131.16 | Methanol carbonylation method
China National Petroleum Daqing Petrochemical Branch | 100 | 84.37 | Ethylene oxidation method
Sinopec Yangzi Petrochemical Co., Ltd. | 85 | 78.54 | Ethylene oxidation method
Sinopec Shanghai Petrochemical Co., Ltd. | 45 | 15.28 | Ethylene oxidation method
Shijiazhuang Xinyu Sanyang Industrial Co., Ltd. | 202 | 0.14 | …

At present, the composition of acetic acid consumption in China is as follows: vinyl acetate and polyvinyl alcohol account for about 20% of the total acetic acid consumption; terephthalic acid accounts for around 18%; ethyl acetate/butyl acetate etc. account for 15%; dyes account for 14%; acetic anhydride accounts for 8%; the pharmaceutical industry accounts for 10%, and other applications account for 15%. In recent years, the supply and demand situation of acetic acid in China is shown in Table 5.
Table 5: Supply and demand situation of acetic acid in China in recent years (kt)
Year | Capacity / kt·a⁻¹ | Production | Imports | Exports | Apparent consumption | Self-sufficiency rate, %
1996 | 673 | 491.0 | 121.4 | 1.06 | 611.4 | 79.97
1997 | 740 | 580.0 | 95.9 | 0.26 | 675.78 | 85.88
1998 | 1,080 | 591.6 | 135.4 | 0.27 | 726.88 | 81.40
1999 | 1,040 | 723.7 | 105.9 | 0.48 | 829.28 | 87.28
2000 | 1,100 | 865.0 | 103.6 | 0.89 | 967.88 | 89.38
2001 | 1,150 | 861.3 | 201.7 | 6.01 | 1,057.08 | 81.48
2002 | 1,200* | 841.0 | 348.6 | 1.31 | 1,188.37 | 70.77
* Includes some idle capacity. As can be seen from Table 5, China imports a certain amount of acetic acid each year, and the import volume is increasing year by year. Not only that, but due to the shortage of acetic acid, a large amount of acetic acid derivatives are also imported, as detailed in Table 6. Table 6: Import volume of acetic acid and its downstream products in China over recent years (in kt)
Year: 1999, 2000, 2001, January–November 2002
Acetic acid: 105.9, 103.6, 201.7, 308.0
Butyl acetate: 49.5, 48.7, 42.4, 57.6
Ethyl acetate: 64.7, 44.1, 53.5, 44.0
Acetic anhydride: 181, 7.5, 21.3, 33.8
Terephthalic acid: 1,542.3, 2,505.3, 1,166.3, 960.0
Vinyl acetate: 39.1, 38.2, 66.6, 134.4
EVA copolymers: 219.7, 239.6, 269.9
With the rapid development of the national economy, the demand for acetic acid is set to continue increasing year by year. It is estimated that China’s demand for acetic acid in 2005 will reach 1,390–1,440 kt. Among these, vinyl acetate/polyvinyl alcohol amounts to 310–330 kt, PTA to 220–230 kt, acetic anhydride/acetic acid to 160–170 kt, the pharmaceutical industry to 130–140 kt, chloroacetic acid to 90 kt, divinylbenzene to 60 kt, dyes/textile printing to 70 kt, synthetic ammonia to 15 kt, and other uses to 165 kt. 5 Conclusion To compete in the international market, China’s acetic acid industry must adjust its industrial and technological structures. The enlargement of such devices has become inevitable; some devices that use outdated technology, have small production scales, high energy consumption, and high production costs will inevitably be phased out. Accelerating the development of the low-pressure methanol carbonylation process is an urgent task, which is reasonable both from a techno-economic perspective and in terms of the raw material supply chain. Some acetic acid production enterprises in our country must carry out renovations and expansions as soon as possible to raise their production capacity to at least 200–300 kt/a. At the same time, in areas where conditions permit, 1–2 new production units with a capacity of 300–500 kt/a should be built, so as to increase the proportion of low-pressure methanol carbonylation processes in our country to at least 60%. Only in this way can the competitiveness of China’s acetic acid in both domestic and international markets be continuously enhanced.