Process technologies for phthalic anhydride and isophthalic anhydride
Thread Content
Question: Which company possesses the process technology for phthalic anhydride and isophthalic anhydride?
As far as I know, there are two companies based in Jiangsu. One is Jiangsu Zhengdan Chemical, and the other is Baichuan Chemical in Jiangyin. They are also the two largest producers in the world.
Phthalic anhydride, also known as phthaloanhydride. The molecular formula is C9H4O5. It appears as white flakes, with a melting point of 165–168°C. Soluble in hot water and acetone, 2-MeTHF, dimethylformamide, ethyl acetate, **. Dissolved in anhydrous ethanol and reacted. Production Methods 1.1 Nitric acid oxidation of p-xylene 1.2 Gas-phase air oxidation of p-xylene 1.3 Liquid-phase air oxidation of p-xylene 1.4 MGC method Applications 2.1 Production of trioctyl trimellitate 2.2 Production of polyamides-imides and polyester-imides 2.3 Production of alkyd resins 2.4 Others Domestic and international production, consumption, and market prospects Production of phthalic anhydride abroad (kt/a); information on the consumption patterns of phthalic anhydride abroad can be found here. Major manufacturers of phthalic anhydride in China. Main uses: Used in the production of polyester resins and polyimide resins, water-soluble polyester resins, water-soluble polyurethane resins, plasticizers, water-soluble amino-alkyd resins, epoxy resin curing agents, as well as high-grade aviation lubricants, insulating oils for electrical capacitors, granule binders, sizing agents, smoke suppressants, instant binders, and TOTM, among others. Quality specifications for phthalic anhydride: These are in accordance with the enterprise standard Q/321181GSH008-2005.
| Specification Name | Premium Grade | First-Class Grade |
|-------------------|---------------|------------------|
| Appearance | White flakes | White or light yellow flakes |
| Purity (%) | ≥ 99.80 | ≥ 99.00 |
| Acid value (mgKOH/g)| ≥ 873.00 | ≥ 865.00 |
| Anhydride content (%)| ≥ 98.50 | ≥ 97.00 |
| Melting point (°C)| 166.0–168.0 | 165.0–168.0 |
| Triethylene glycol (TEG) colority, Pt-Co | ≤ 35# | ≤ 50# |
| Melting colority, Pt-Co | ≤ 100# | — |
| PA ppm | ≤ 500 | — |
| CAS No.: | 552-30-7 | — |
| Chemical structure formula: Structure of phthalic anhydride (1 image) | | |
Production method: Phthalic anhydride was first discovered as a by-product when tetraalkylbenzenes were subjected to vapor-phase oxidation to produce pyromellitic dianhydride. Currently, the main production methods include the nitric acid oxidation of p-xylene, the gas-phase oxidation of p-xylene, the liquid-phase air oxidation of p-xylene, and the MGC method. 1.1 Nitric acid oxidation of p-xylene Under conditions of 1.5–3.0 MPa and 180–205 °C, p-xylene is oxidized using dilute nitric acid to produce p-terephthalic acid; this acid is then heated and dehydrated to yield p-terephthalic anhydride. The reaction equation is as follows: This method is simple to operate, with a yield of 90% and a product purity of up to 98.5%. However, it causes severe corrosion, requires high-quality materials for the equipment, and also presents significant problems related to waste generation. The German company Saarbergwerk adopted this method for industrial production in 1970, but it stopped operating due to high costs, severe waste problems, and dangerous operating conditions. Chinese facilities such as the Beijing Coking Plant also used this method for small-scale production. This method has been largely phased out. 1.2 Gas-phase air oxidation of p-xylene The gas-phase air oxidation method for p-xylene was developed by Nippon Catalyst Chemical Industry Co., Ltd. It uses compounds containing vanadium, titanium, and phosphorus as catalysts; p-xylene is oxidized to produce trimellitic acid, which is then dehydrated to yield trimellitic anhydride. This method has advantages such as simple process and low equipment investment, but due to the poor selectivity of the catalyst used and low yields, there are no reports of its industrial application to date. 1.3 Liquid-phase air oxidation of p-xylene This method was first developed successfully by the Mid-Century company in the United States, and is referred to as the MC method. In 1962, the American company Amoco was the first to use this method for industrial production, which is why it is also known as the Amoco process. Using acetic acid as a solvent and a soluble substance containing cobalt, manganese metal components, and bromides as a catalyst, p-xylene is oxidized to p-terephthalic acid using air at 200 °C and 2.0 MPa pressure; p-terephthalic acid is then dehydrated to p-terephthalic anhydride. The yield of trimellitic anhydride, based on p-xylene, can reach 130%, with a product purity of 99%. The reaction equation is: Figure 1 shows the process flow for producing phthalic anhydride using the Amoco method. This method has advantages such as readily available raw materials, low consumption of raw materials and utility resources, minimal corrosion, and easier handling of waste issues; it is therefore the main method used in industry both domestically and internationally for the production of phthalic anhydride. Its process mainly consists of three steps: oxidation reaction, solvent concentration, and dehydration to form an anhydride. The process flow diagram is shown in Figure 1. 1.4 MGC Method The MGC method uses m-xylene as a raw material, and its production process mainly consists of two steps: the production of aromatic aldehydes and the oxidation in an aqueous solution. Under the catalysis of the liquid superacid HF-BF3, it undergoes formylation with CO to yield 2,4-diformaldehyde (also known as aromatic aldehyde). In an aqueous solution, using manganese bromide and hydrogen bromide as catalysts, at temperatures of 200–220 °C and pressures of 1.96–2.94 MPa, air is used to oxidize 2,4-diformaldehyde to produce trimellitic acid; trimellitic acid is then dehydrated to yield trimellitic anhydride. The process flow is shown in Figure 2, and the main reaction equation is as follows: This method has advantages such as readily available raw materials, low consumption of raw materials and utility resources, minimal corrosion, and easier resolution of waste issues; it is currently the primary method used in industry both domestically and internationally for the production of phthalic anhydride. Its process mainly consists of three steps: oxidation reaction, solvent concentration, and dehydration to form an anhydride. The process flow diagram is shown in Figure 1. Compared with the traditional liquid-phase air oxidation of p-xylene to produce phthalic anhydride, this method features inexpensive and readily available raw materials, a continuous reaction process, and ease of automated control. The reaction process uses water as a solvent, eliminating the risk of solvent evaporation losses and potential steam explosions. The aqueous solution and the water produced by the reaction can be easily separated, which helps to reduce equipment costs and simplifies the solvent recovery system. However, the downside is that the oxidation takes place at high temperatures in an aqueous solution, requiring oxidation equipment made from expensive nickel-based or titanium/zirconium-based alloys, thus increasing the cost of the project. Furthermore, both the preparation of aromatic aldehydes and aqueous solvent oxidation employ strongly acidic catalysts, causing severe corrosion. Figure 2: Process flow for the production of trimellitic anhydride using the MGC method. Applications: 2.1 Production of trioctyl trimellitate Trioctyl trimellitate (abbreviated as TOTM), which is obtained through the esterification of trimellitic anhydride with octanol, possesses good heat resistance, low volatility, oil resistance, and processability. It is widely used as a heat-resistant plasticizer for PVC, as a plasticizer for solvent-resistant cross-linked vinyl chloride resins, as the main plasticizer in heat-resistant cable formulations at 90 °C and 105 °C, and as an auxiliary plasticizer required for high-voltage cables of 6,000 V and 10,000 V. In addition, it can also be used as an impregnating agent and a high-temperature resistant insulating paint, and is widely used as a coating material for components inside electrical devices, wires in automobiles, semiconductors, and so on ； Used as components in automotive cables, moisture-proof and heat-resistant epoxy resin capsules, anti-fogging polyethylene resin components, as well as anhydrous dye components for fibers and thermoplastics ； It is used for car seat cushions, synthetic leather, washing machine drain hoses, blind curtains, sealing materials, and fillers, among other things. 2.2 Preparation of polyamide-imides and polyesterimides Polyamide-imides can be prepared by reacting phthalic anhydride with aromatic diamines, while polyesterimides can be obtained by reacting phthalic anhydride, hydroquinone, and 4,4’-diaminodihydroxyphenyl ether. They all possess excellent heat resistance, electrical insulation properties, and mechanical strength; they also exhibit good wear resistance at high temperatures. They are primarily used as insulating materials for F and H class motors, such as enameling varnishes, impregnating varnishes, silicon steel sheet coatings, and films, and can be used continuously at temperatures between 230 and 250 °C. It can also be used to manufacture molded plastic components such as electrical components, valve parts, bearings, and jet engine parts. 2.3 Preparation of alkyd resins Alkyd resin coatings with excellent properties can be obtained by reacting phthalic anhydride with polyols and dicarboxylic acids. Thermoplastic alkyd resins are primarily used as primers for automobiles, electrical appliances, and mechanical products; they can also be used as topcoats for kitchens, furniture, etc., as well as in industrial building materials and common paints. Resins that cure at room temperature are mainly used in industrial building materials and common paints. 2.4 Others Phthalic anhydride can cause epoxy resins to cure in a short time and endow the cured resins with excellent physical and chemical properties; it is an inexpensive and practical curing agent. It can also be used to produce polyester resins and powder coatings, and is widely used in applications such as home appliances, bicycles, steel doors, and windows where high decorative and corrosion-resistant properties are required. It is used in heat-resistant insulating laminates, synthetic dyes, heat-resistant varnishes, stabilizers, fiber softeners, pigments, water treatment agents, film stock, and surfactants, among other applications. Edit this section: Domestic and international production, consumption, and market prospects. Abroad, research and development on industrial production methods for phthalic anhydride began as early as the 1950s. In 1962, the American company Amoco was the first to implement industrial production using the liquid-phase air oxidation method with p-xylene, and in 1968 a production facility with a capacity of 13 kt/a was built at its plant in Joliet, Illinois. In 1993, the company built a 23 kt/a production facility at its plant in Geel, Belgium, using a new improved process for the liquid-phase air oxidation of p-xylene ； In 1968, Nihon Taikai Kaku and Katsuya Kagaku Company began production using the air oxidation method respectively ； In 1970, the German company Saarbergwerk built a production facility using the nitration of p-xylene; production was halted later due to high costs, serious problems with waste generation, and safety hazards ； In 1985, Mitsubishi Gas Chemical Company in Japan developed a new process (the MGC process) for producing trimellitic anhydride using m-xylene as a raw material, through the air oxidation of aromatic aldehydes in an aqueous solution; a production facility with a capacity of 15 kt/a was built in Mizushima. After this facility was built and put into operation, significant changes occurred in the phthalic anhydride market, which had previously been monopolized by the American company Amoco. The Japanese market (accounting for about one-third of the world market) is now dominated by Mitsubishi Gas Chemical Company. In addition, Japanese distillation industry companies such as Mitsui Toyo Press also have production facilities for phthalic anhydride with a capacity of thousands of tons. The current global production capacity for phthalic anhydride is approximately 100 kt/a, of which the capacity utilizing BP-Amoco’s production technology accounts for about 31.21% of the total global production capacity for phthalic anhydride. The production status of the main manufacturers of phthalic anhydride abroad is shown in Table 1. Production of phthalic anhydride abroad (kt/a):
Manufacturer | Production capacity
BP-Amoco Chemical Company | 31.8
Alusuisse Company (Italy) | 20.0
Amoco Belgium nv (Belgium) | 22.7
Saarbergwerk Company (Germany) | 1.5
AGIG Company (Japan) | 15
Mitsui East Asia Company (Japan) | 1.2
Distillation Industry Company (Japan) | 1.2
Otsuka Company (Japan) | 1.2
Others | 7.3
Total | 101.9
For information on the consumption patterns of phthalic anhydride abroad, please refer to the relevant data. Abroad, the rights to sell phthalic anhydride are mainly held by BP-Amoco Company. In 1999, the global consumption of phthalic anhydride was 67.6 kt/a, of which 21.4 kt/a came from the United States, accounting for 31.66% of the total consumption ； Western Europe accounts for 24.8 kt/a, representing 36.69% of the total consumption ； Japan accounts for 19.2 kt/a, representing 28.4% of the total consumption, while other regions account for 3.25%. Consumption composition of phthalic anhydride abroad in 1996 and 1999 (%):
Application | 1996 | 1999 | United States | Western Europe | Japan | United States | Western Europe | Japan
Phthalate plasticizers | 60.0 | 50.0 | 45.0 | 55.0 | 45.0 | 48.0
Alkyd and saturated polyester for coatings | 30.0 | 45.0 | 35.0 | 32.0 | 40.0 | 40.0
Polyimides | 5.0 | – | – | 10.0 | – | –
Resin curing agents | – | – | 15.0 | – | 10.0 | 10.0
Others | 5.0 | 5.0 | 5.0 | 3.0 | 5.0 | 2.0
Total | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0
Main manufacturers of phthalic anhydride in China:
Research and development on phthalic anhydride in China started relatively late. At the end of the 1960s, the Heilongjiang Provincial Petrochemical Research Institute and Nanjing Paint Factory jointly carried out research on the liquid-phase oxidation of p-xylene to produce phthalic anhydride, and established a 250 t/a pilot-scale testing facility at Nanjing Paint Factory. This device uses acetic acid as the solvent, cobalt acetate, manganese acetate, and tetraethyl bromide as catalysts. The reaction temperature is 170 °C, and the oxidation pressure is 2.2 MPa. The oxidation products are first subjected to vacuum flashing, followed by vacuum distillation to recover the solvent. The yield of p-terephthalic anhydride to p-tert-butylbenzene is 100%–110%, with a product purity of 95%–98%; this pilot plant had to be shut down due to unresolved engineering problems ； Subsequently, the Heilongjiang Petrochemical Research Institute, in collaboration with the Harbin Petrochemical Plant, built a 300 t/a phthalic anhydride production facility, which also stopped operating after half a year due to certain issues. Later, Harbin Petrochemical Plant expanded the facility to a capacity of 3,000 t/a. However, due to the use of a continuous production process, the technical challenges increased significantly; many problems arose during commissioning that were difficult to resolve, which forced the plant to suspend operations. It was only recently that production was resumed ； In 1992, Jianghai Chemical Company in Wuxi, Jiangsu built a production facility with a capacity of 300 t/a ； In 1995, the Changjing Acetic Anhydride Plant in Jiangyin, Jiangsu, built a production facility with a capacity of 500 t/a; it operated fairly well, and the product quality met the requirements of customers. At the end of 1997, the plant built another production unit with an annual capacity of 1,500 t/a. The trial production went well, and compared to the original unit, the product quality improved significantly while consumption was greatly reduced. At present, China’s total production capacity for phthalic anhydride is 7,800 t/year, with output of less than 2,000 t/year; consumption amounts to approximately 12.8 kt/year, and the batch process is primarily used in its production. The main manufacturers of phthalic anhydride in our country are shown in Table 3. Overview of the main manufacturers of phthalic anhydride in China (t/a)
Manufacturer Production Capacity
Harbin Petrochemical Plant 3,000
Jiangsu Wuxi Jianghai Chemical Company 300
Henan Puyang Organic Chemical Plant 1,500
Jiangsu Jiangyin Changjing Acetic Anhydride Factory 2,000
Changzhou Boda Chemical Co., Ltd. 1,000
Total 7,800
In China, phthalic anhydride is primarily used in the production of PVC heat-resistant plasticizer, phthalic anhydride trioctyl ester (TOTM). With the development of China’s PVC wire and cable industry, the demand for trioxane trioctyl ester will continue to increase. It is estimated that China’s demand for TOTM in 2005 will be around 18.5 kt/a, with the corresponding demand for phthalic anhydride at 8.322 kt/a. During the period from 2000 to 2005, the average annual growth rate of phthalic anhydride consumption in this sector was 6.0%. Powder coatings made by using phthalic anhydride as a raw material to produce polyester resin, which is then mixed with epoxy resin in a 1:1 ratio, are widely used in applications such as home appliances, bicycles, steel doors, and windows where high decorative and corrosion-resistant properties are required. In recent years, powder coatings in our country have developed rapidly, with polyester/epoxy powder coatings accounting for about 80% of them. In 2000, China’s polyester production capacity was 89.5 kt/year, with a production volume of 38.2 kt/year, and 4.96 kt of phthalic anhydride was consumed. At present, the production of light industry and household appliance products in our country is among the best in the world, and it is about to enter a new period of development. There are higher demands regarding the output, variety, styles, and performance of coating products. It is estimated that by 2005, China will need 180 kt of powder coatings, of which 140 kt will be polyester/epoxy powder coatings; approximately 44.8 kt of polyester will be required per year, with a corresponding demand for phthalic anhydride of 6.421 tons per year. Between 2000 and 2005, the average annual growth rate of phthalic anhydride consumption in this sector was 5.3%. The polyimides, polyamide-imide coatings, and polyester-imide coatings produced in our country from phthalic anhydride are primarily used as insulation materials for F-class and H-class motors. In the past, most motor insulation materials in our country were of grade A, E, or B; motors using F-grade or H-grade insulation materials accounted for only 1% to 2% of the total (over 50% abroad). Since the 1980s, explosion-proof motors, crane motors, and DC motors in China have required the use of F-class insulation materials, which has led to a rapid increase in the consumption of phthalic anhydride in the country. In 2000, China’s production capacity for high-grade insulation materials was 6,300 tons per year, with 945 tons of phthalic anhydride being consumed annually. It is estimated that by 2005, the demand for phthalic anhydride in this sector would be 1,206 tons per year; the average annual growth rate of phthalic anhydride consumption in this field from 2000 to 2005 was 5.0%. Phthalic anhydride can also be used to produce high-temperature curing agents for epoxy resins. China’s coating industry is moving toward non-toxic and flame-retardant solutions. Water-soluble resin coatings can be obtained by using resins derived from reactions such as those between phthalic anhydride and ethylene glycol, diol monoglycerides, hexanediol, propylene glycol, neopentyl glycol, and other diols; these coatings are used as electrophoretic primers for automobiles, refrigerators, and washing machines. Phthalic anhydride can cure resins in a short time, possesses excellent physical and chemical properties, and is an ideal curing agent for high-temperature applications. In 2000, China consumed 600 tons of phthalic anhydride as a high-temperature curing agent for coatings and epoxy resins; this figure was expected to rise to 800 tons by 2005. During the period 2000–2005, the average annual growth rate of phthalic anhydride consumption in this sector was 5.9%. Including consumption in other areas, it is estimated that China’s total demand for phthalic anhydride will reach 16.9 kt by 2005, with an average annual growth rate of market demand of 5.7% from 2000 to 2005. The specific consumption breakdown is shown in Table 4. Table 4 Forecast for China’s phthalic anhydride market in 2005
Consumption sector, Demand amount/t, Consumption composition, %
TOTM plasticizers: 8,322 t, 49.24%
Polyester esters: 6,421 t, 38.00%
Advanced insulating materials: 1,206 t, 7.14%
High-temperature curing agents: 800 t, 4.73%
Others: 151 t, 0.89%
Total: 16,900 t, 100.00%
Although phthalic anhydride has a wide range of applications, China’s production capacity and output of this substance have remained low.
BCCTMA
Phthalic anhydride
MSDS number: 0127815545CN
1.0 Chemical product and company name
Product name: Phthalic anhydride (TMA)
Manufacturer/supplier: Wuxi Baichuan Chemical Co., Ltd.
Location: Area B, Yunting Industrial Park, Jiangyin City, Jiangsu Province, China
Postal code: 214422
2.0 Composition and details
Component, CAS number, Weight percentage
Phthalic anhydride, 552-30-7, 100%
(For exposure guidelines, see Section 8.0 “Exposure Control/Personal Protection”)
3.0 Hazard information
Overview of acute effects: Causes eye damage. Causes moderate skin irritation. It causes respiratory irritation. It can cause allergic respiratory reactions. Gastrointestinal irritation. Potential health effects: Contact with eyes: Harmful to the eyes. Contact with skin: Causes moderate skin irritation. Inhalation: Causes irritation of the respiratory tract. It can cause allergic respiratory reactions. When ingested: gastrointestinal irritation. HMIS Code: (Health: 3) (Flammability: 1) (Reactivity: 1) NFPA Code: (Health: 3) (Flammability: 1) (Reactivity: 1) 4.0 First Aid Measures Eyes: Flush immediately with plenty of water for at least 15 minutes, then seek medical attention right away. Skin: Wash the skin that came into contact with it using water and soap, remove the contaminated clothing, and ensure it is thoroughly washed and dried before use again. Seek medical attention if there are symptoms of irritation. Inhalation: Once swallowed, drink plenty of water. Induce vomiting only under a doctor's supervision. Seek medical attention immediately. Physicians note: Acute TMA asthma reactions should be treated in the same way as asthma caused by other factors. The initial assessment of the patient’s condition included measuring peak expiratory flow rate (PEFR) and forced expiratory volume in one second (FEV1). If both indicators exceed 80% of the expected value, treatment with only beta-receptor agonists is sufficient. If it is less than 80% or if the patient does not respond to treatment with β-receptor agonists alone, a complete blood count, chest X-ray, and arterial blood gas (ABGs) must be performed. If the patient develops cyanosis and acute dyspnea, oxygen therapy and the administration of systemic corticosteroids should be considered. The basic treatment for severe respiratory syndrome (TMA infection) is systemic corticosteroid therapy, with the use of bronchodilators if necessary. 5.0 Fire protection measures Ignition point: 440°F (220°C) Upper explosion limit: 7% Lower explosion limit: 1% Natural ignition temperature: Uncertain Flammability classification: None Extinguishing media: Agents suitable for extinguishing Class A fires (such as foam extinguishers, steam extinguishers) or water mist. Special fire and explosion hazards: High dust concentrations pose a potential risk of combustion and explosion. When there is a large amount of dust present, high-voltage electrostatic discharge and accumulation should be avoided. Firefighting equipment: Firefighters must be fully equipped, including self-provided positive-pressure oxygen supply devices. Prevention: Take preventive measures against static discharge, including ensuring complete connection between circuits, using grounded equipment, and transporting in an inert gas environment. 6.0 Measures to Avoid Accidents Vacuuming: To prevent dust from forming. Improve ventilation. 7.0 Operation and Storage Operation: Ensure adequate ventilation. Minimize the generation and accumulation of dust. Avoid static electricity buildup. Storage: Ensure adequate ventilation. 8.0 Exposure Control/Personal Protection Eyes: Do not get it in the eyes. Wear chemical goggles and a face shield. Skin: Avoid skin contact. Put on protective clothing and gloves. Breathing: Ensure adequate ventilation. If ventilation is insufficient, use a respirator that combines organic vapor filters with humor filters. Engineering controls: Keep the concentration in the air below the levels specified by the exposure guidelines. Guidelines for exposure exposure: Component CAS Number Exposure limit concentration Phthalic anhydride 552-30-7 OSHA PEL: 0.04 mg/m³ (1989) ； No standard established (1971). ACGIH limit: 0.04 mg/m³. 9.0 Chemical and physical properties: Appearance and odor: White. Flaky. Foul smell. PH: 2.0 Vapor pressure: less than 1.1*10 at 25°C Vapor density: 6.6 Boiling point: 730°F (390°C) Melting point: 330°F (165°C) Solubility in water: moderately soluble after acid hydrolysis. Specific gravity (water=1): 1.54
| Specification Name | Premium Grade | First-Class Grade |
|-------------------|---------------|------------------|
| Appearance | White flakes | White or light yellow flakes |
| Purity (%) | ≥ 99.80 | ≥ 99.00 |
| Acid value (mgKOH/g)| ≥ 873.00 | ≥ 865.00 |
| Anhydride content (%)| ≥ 98.50 | ≥ 97.00 |
| Melting point (°C)| 166.0–168.0 | 165.0–168.0 |
| Triethylene glycol (TEG) colority, Pt-Co | ≤ 35# | ≤ 50# |
| Melting colority, Pt-Co | ≤ 100# | — |
| PA ppm | ≤ 500 | — |
| CAS No.: | 552-30-7 | — |
| Chemical structure formula: Structure of phthalic anhydride (1 image) | | |
Production method: Phthalic anhydride was first discovered as a by-product when tetraalkylbenzenes were subjected to vapor-phase oxidation to produce pyromellitic dianhydride. Currently, the main production methods include the nitric acid oxidation of p-xylene, the gas-phase oxidation of p-xylene, the liquid-phase air oxidation of p-xylene, and the MGC method. 1.1 Nitric acid oxidation of p-xylene Under conditions of 1.5–3.0 MPa and 180–205 °C, p-xylene is oxidized using dilute nitric acid to produce p-terephthalic acid; this acid is then heated and dehydrated to yield p-terephthalic anhydride. The reaction equation is as follows: This method is simple to operate, with a yield of 90% and a product purity of up to 98.5%. However, it causes severe corrosion, requires high-quality materials for the equipment, and also presents significant problems related to waste generation. The German company Saarbergwerk adopted this method for industrial production in 1970, but it stopped operating due to high costs, severe waste problems, and dangerous operating conditions. Chinese facilities such as the Beijing Coking Plant also used this method for small-scale production. This method has been largely phased out. 1.2 Gas-phase air oxidation of p-xylene The gas-phase air oxidation method for p-xylene was developed by Nippon Catalyst Chemical Industry Co., Ltd. It uses compounds containing vanadium, titanium, and phosphorus as catalysts; p-xylene is oxidized to produce trimellitic acid, which is then dehydrated to yield trimellitic anhydride. This method has advantages such as simple process and low equipment investment, but due to the poor selectivity of the catalyst used and low yields, there are no reports of its industrial application to date. 1.3 Liquid-phase air oxidation of p-xylene This method was first developed successfully by the Mid-Century company in the United States, and is referred to as the MC method. In 1962, the American company Amoco was the first to use this method for industrial production, which is why it is also known as the Amoco process. Using acetic acid as a solvent and a soluble substance containing cobalt, manganese metal components, and bromides as a catalyst, p-xylene is oxidized to p-terephthalic acid using air at 200 °C and 2.0 MPa pressure; p-terephthalic acid is then dehydrated to p-terephthalic anhydride. The yield of trimellitic anhydride, based on p-xylene, can reach 130%, with a product purity of 99%. The reaction equation is: Figure 1 shows the process flow for producing phthalic anhydride using the Amoco method. This method has advantages such as readily available raw materials, low consumption of raw materials and utility resources, minimal corrosion, and easier handling of waste issues; it is therefore the main method used in industry both domestically and internationally for the production of phthalic anhydride. Its process mainly consists of three steps: oxidation reaction, solvent concentration, and dehydration to form an anhydride. The process flow diagram is shown in Figure 1. 1.4 MGC Method The MGC method uses m-xylene as a raw material, and its production process mainly consists of two steps: the production of aromatic aldehydes and the oxidation in an aqueous solution. Under the catalysis of the liquid superacid HF-BF3, it undergoes formylation with CO to yield 2,4-diformaldehyde (also known as aromatic aldehyde). In an aqueous solution, using manganese bromide and hydrogen bromide as catalysts, at temperatures of 200–220 °C and pressures of 1.96–2.94 MPa, air is used to oxidize 2,4-diformaldehyde to produce trimellitic acid; trimellitic acid is then dehydrated to yield trimellitic anhydride. The process flow is shown in Figure 2, and the main reaction equation is as follows: This method has advantages such as readily available raw materials, low consumption of raw materials and utility resources, minimal corrosion, and easier resolution of waste issues; it is currently the primary method used in industry both domestically and internationally for the production of phthalic anhydride. Its process mainly consists of three steps: oxidation reaction, solvent concentration, and dehydration to form an anhydride. The process flow diagram is shown in Figure 1. Compared with the traditional liquid-phase air oxidation of p-xylene to produce phthalic anhydride, this method features inexpensive and readily available raw materials, a continuous reaction process, and ease of automated control. The reaction process uses water as a solvent, eliminating the risk of solvent evaporation losses and potential steam explosions. The aqueous solution and the water produced by the reaction can be easily separated, which helps to reduce equipment costs and simplifies the solvent recovery system. However, the downside is that the oxidation takes place at high temperatures in an aqueous solution, requiring oxidation equipment made from expensive nickel-based or titanium/zirconium-based alloys, thus increasing the cost of the project. Furthermore, both the preparation of aromatic aldehydes and aqueous solvent oxidation employ strongly acidic catalysts, causing severe corrosion. Figure 2: Process flow for the production of trimellitic anhydride using the MGC method. Applications: 2.1 Production of trioctyl trimellitate Trioctyl trimellitate (abbreviated as TOTM), which is obtained through the esterification of trimellitic anhydride with octanol, possesses good heat resistance, low volatility, oil resistance, and processability. It is widely used as a heat-resistant plasticizer for PVC, as a plasticizer for solvent-resistant cross-linked vinyl chloride resins, as the main plasticizer in heat-resistant cable formulations at 90 °C and 105 °C, and as an auxiliary plasticizer required for high-voltage cables of 6,000 V and 10,000 V. In addition, it can also be used as an impregnating agent and a high-temperature resistant insulating paint, and is widely used as a coating material for components inside electrical devices, wires in automobiles, semiconductors, and so on ； Used as components in automotive cables, moisture-proof and heat-resistant epoxy resin capsules, anti-fogging polyethylene resin components, as well as anhydrous dye components for fibers and thermoplastics ； It is used for car seat cushions, synthetic leather, washing machine drain hoses, blind curtains, sealing materials, and fillers, among other things. 2.2 Preparation of polyamide-imides and polyesterimides Polyamide-imides can be prepared by reacting phthalic anhydride with aromatic diamines, while polyesterimides can be obtained by reacting phthalic anhydride, hydroquinone, and 4,4’-diaminodihydroxyphenyl ether. They all possess excellent heat resistance, electrical insulation properties, and mechanical strength; they also exhibit good wear resistance at high temperatures. They are primarily used as insulating materials for F and H class motors, such as enameling varnishes, impregnating varnishes, silicon steel sheet coatings, and films, and can be used continuously at temperatures between 230 and 250 °C. It can also be used to manufacture molded plastic components such as electrical components, valve parts, bearings, and jet engine parts. 2.3 Preparation of alkyd resins Alkyd resin coatings with excellent properties can be obtained by reacting phthalic anhydride with polyols and dicarboxylic acids. Thermoplastic alkyd resins are primarily used as primers for automobiles, electrical appliances, and mechanical products; they can also be used as topcoats for kitchens, furniture, etc., as well as in industrial building materials and common paints. Resins that cure at room temperature are mainly used in industrial building materials and common paints. 2.4 Others Phthalic anhydride can cause epoxy resins to cure in a short time and endow the cured resins with excellent physical and chemical properties; it is an inexpensive and practical curing agent. It can also be used to produce polyester resins and powder coatings, and is widely used in applications such as home appliances, bicycles, steel doors, and windows where high decorative and corrosion-resistant properties are required. It is used in heat-resistant insulating laminates, synthetic dyes, heat-resistant varnishes, stabilizers, fiber softeners, pigments, water treatment agents, film stock, and surfactants, among other applications. Edit this section: Domestic and international production, consumption, and market prospects. Abroad, research and development on industrial production methods for phthalic anhydride began as early as the 1950s. In 1962, the American company Amoco was the first to implement industrial production using the liquid-phase air oxidation method with p-xylene, and in 1968 a production facility with a capacity of 13 kt/a was built at its plant in Joliet, Illinois. In 1993, the company built a 23 kt/a production facility at its plant in Geel, Belgium, using a new improved process for the liquid-phase air oxidation of p-xylene ； In 1968, Nihon Taikai Kaku and Katsuya Kagaku Company began production using the air oxidation method respectively ； In 1970, the German company Saarbergwerk built a production facility using the nitration of p-xylene; production was halted later due to high costs, serious problems with waste generation, and safety hazards ； In 1985, Mitsubishi Gas Chemical Company in Japan developed a new process (the MGC process) for producing trimellitic anhydride using m-xylene as a raw material, through the air oxidation of aromatic aldehydes in an aqueous solution; a production facility with a capacity of 15 kt/a was built in Mizushima. After this facility was built and put into operation, significant changes occurred in the phthalic anhydride market, which had previously been monopolized by the American company Amoco. The Japanese market (accounting for about one-third of the world market) is now dominated by Mitsubishi Gas Chemical Company. In addition, Japanese distillation industry companies such as Mitsui Toyo Press also have production facilities for phthalic anhydride with a capacity of thousands of tons. The current global production capacity for phthalic anhydride is approximately 100 kt/a, of which the capacity utilizing BP-Amoco’s production technology accounts for about 31.21% of the total global production capacity for phthalic anhydride. The production status of the main manufacturers of phthalic anhydride abroad is shown in Table 1. Production of phthalic anhydride abroad (kt/a):
Manufacturer | Production capacity
BP-Amoco Chemical Company | 31.8
Alusuisse Company (Italy) | 20.0
Amoco Belgium nv (Belgium) | 22.7
Saarbergwerk Company (Germany) | 1.5
AGIG Company (Japan) | 15
Mitsui East Asia Company (Japan) | 1.2
Distillation Industry Company (Japan) | 1.2
Otsuka Company (Japan) | 1.2
Others | 7.3
Total | 101.9
For information on the consumption patterns of phthalic anhydride abroad, please refer to the relevant data. Abroad, the rights to sell phthalic anhydride are mainly held by BP-Amoco Company. In 1999, the global consumption of phthalic anhydride was 67.6 kt/a, of which 21.4 kt/a came from the United States, accounting for 31.66% of the total consumption ； Western Europe accounts for 24.8 kt/a, representing 36.69% of the total consumption ； Japan accounts for 19.2 kt/a, representing 28.4% of the total consumption, while other regions account for 3.25%. Consumption composition of phthalic anhydride abroad in 1996 and 1999 (%):
Application | 1996 | 1999 | United States | Western Europe | Japan | United States | Western Europe | Japan
Phthalate plasticizers | 60.0 | 50.0 | 45.0 | 55.0 | 45.0 | 48.0
Alkyd and saturated polyester for coatings | 30.0 | 45.0 | 35.0 | 32.0 | 40.0 | 40.0
Polyimides | 5.0 | – | – | 10.0 | – | –
Resin curing agents | – | – | 15.0 | – | 10.0 | 10.0
Others | 5.0 | 5.0 | 5.0 | 3.0 | 5.0 | 2.0
Total | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0
Main manufacturers of phthalic anhydride in China:
Research and development on phthalic anhydride in China started relatively late. At the end of the 1960s, the Heilongjiang Provincial Petrochemical Research Institute and Nanjing Paint Factory jointly carried out research on the liquid-phase oxidation of p-xylene to produce phthalic anhydride, and established a 250 t/a pilot-scale testing facility at Nanjing Paint Factory. This device uses acetic acid as the solvent, cobalt acetate, manganese acetate, and tetraethyl bromide as catalysts. The reaction temperature is 170 °C, and the oxidation pressure is 2.2 MPa. The oxidation products are first subjected to vacuum flashing, followed by vacuum distillation to recover the solvent. The yield of p-terephthalic anhydride to p-tert-butylbenzene is 100%–110%, with a product purity of 95%–98%; this pilot plant had to be shut down due to unresolved engineering problems ； Subsequently, the Heilongjiang Petrochemical Research Institute, in collaboration with the Harbin Petrochemical Plant, built a 300 t/a phthalic anhydride production facility, which also stopped operating after half a year due to certain issues. Later, Harbin Petrochemical Plant expanded the facility to a capacity of 3,000 t/a. However, due to the use of a continuous production process, the technical challenges increased significantly; many problems arose during commissioning that were difficult to resolve, which forced the plant to suspend operations. It was only recently that production was resumed ； In 1992, Jianghai Chemical Company in Wuxi, Jiangsu built a production facility with a capacity of 300 t/a ； In 1995, the Changjing Acetic Anhydride Plant in Jiangyin, Jiangsu, built a production facility with a capacity of 500 t/a; it operated fairly well, and the product quality met the requirements of customers. At the end of 1997, the plant built another production unit with an annual capacity of 1,500 t/a. The trial production went well, and compared to the original unit, the product quality improved significantly while consumption was greatly reduced. At present, China’s total production capacity for phthalic anhydride is 7,800 t/year, with output of less than 2,000 t/year; consumption amounts to approximately 12.8 kt/year, and the batch process is primarily used in its production. The main manufacturers of phthalic anhydride in our country are shown in Table 3. Overview of the main manufacturers of phthalic anhydride in China (t/a)
Manufacturer Production Capacity
Harbin Petrochemical Plant 3,000
Jiangsu Wuxi Jianghai Chemical Company 300
Henan Puyang Organic Chemical Plant 1,500
Jiangsu Jiangyin Changjing Acetic Anhydride Factory 2,000
Changzhou Boda Chemical Co., Ltd. 1,000
Total 7,800
In China, phthalic anhydride is primarily used in the production of PVC heat-resistant plasticizer, phthalic anhydride trioctyl ester (TOTM). With the development of China’s PVC wire and cable industry, the demand for trioxane trioctyl ester will continue to increase. It is estimated that China’s demand for TOTM in 2005 will be around 18.5 kt/a, with the corresponding demand for phthalic anhydride at 8.322 kt/a. During the period from 2000 to 2005, the average annual growth rate of phthalic anhydride consumption in this sector was 6.0%. Powder coatings made by using phthalic anhydride as a raw material to produce polyester resin, which is then mixed with epoxy resin in a 1:1 ratio, are widely used in applications such as home appliances, bicycles, steel doors, and windows where high decorative and corrosion-resistant properties are required. In recent years, powder coatings in our country have developed rapidly, with polyester/epoxy powder coatings accounting for about 80% of them. In 2000, China’s polyester production capacity was 89.5 kt/year, with a production volume of 38.2 kt/year, and 4.96 kt of phthalic anhydride was consumed. At present, the production of light industry and household appliance products in our country is among the best in the world, and it is about to enter a new period of development. There are higher demands regarding the output, variety, styles, and performance of coating products. It is estimated that by 2005, China will need 180 kt of powder coatings, of which 140 kt will be polyester/epoxy powder coatings; approximately 44.8 kt of polyester will be required per year, with a corresponding demand for phthalic anhydride of 6.421 tons per year. Between 2000 and 2005, the average annual growth rate of phthalic anhydride consumption in this sector was 5.3%. The polyimides, polyamide-imide coatings, and polyester-imide coatings produced in our country from phthalic anhydride are primarily used as insulation materials for F-class and H-class motors. In the past, most motor insulation materials in our country were of grade A, E, or B; motors using F-grade or H-grade insulation materials accounted for only 1% to 2% of the total (over 50% abroad). Since the 1980s, explosion-proof motors, crane motors, and DC motors in China have required the use of F-class insulation materials, which has led to a rapid increase in the consumption of phthalic anhydride in the country. In 2000, China’s production capacity for high-grade insulation materials was 6,300 tons per year, with 945 tons of phthalic anhydride being consumed annually. It is estimated that by 2005, the demand for phthalic anhydride in this sector would be 1,206 tons per year; the average annual growth rate of phthalic anhydride consumption in this field from 2000 to 2005 was 5.0%. Phthalic anhydride can also be used to produce high-temperature curing agents for epoxy resins. China’s coating industry is moving toward non-toxic and flame-retardant solutions. Water-soluble resin coatings can be obtained by using resins derived from reactions such as those between phthalic anhydride and ethylene glycol, diol monoglycerides, hexanediol, propylene glycol, neopentyl glycol, and other diols; these coatings are used as electrophoretic primers for automobiles, refrigerators, and washing machines. Phthalic anhydride can cure resins in a short time, possesses excellent physical and chemical properties, and is an ideal curing agent for high-temperature applications. In 2000, China consumed 600 tons of phthalic anhydride as a high-temperature curing agent for coatings and epoxy resins; this figure was expected to rise to 800 tons by 2005. During the period 2000–2005, the average annual growth rate of phthalic anhydride consumption in this sector was 5.9%. Including consumption in other areas, it is estimated that China’s total demand for phthalic anhydride will reach 16.9 kt by 2005, with an average annual growth rate of market demand of 5.7% from 2000 to 2005. The specific consumption breakdown is shown in Table 4. Table 4 Forecast for China’s phthalic anhydride market in 2005
Consumption sector, Demand amount/t, Consumption composition, %
TOTM plasticizers: 8,322 t, 49.24%
Polyester esters: 6,421 t, 38.00%
Advanced insulating materials: 1,206 t, 7.14%
High-temperature curing agents: 800 t, 4.73%
Others: 151 t, 0.89%
Total: 16,900 t, 100.00%
Although phthalic anhydride has a wide range of applications, China’s production capacity and output of this substance have remained low.
BCCTMA
Phthalic anhydride
MSDS number: 0127815545CN
1.0 Chemical product and company name
Product name: Phthalic anhydride (TMA)
Manufacturer/supplier: Wuxi Baichuan Chemical Co., Ltd.
Location: Area B, Yunting Industrial Park, Jiangyin City, Jiangsu Province, China
Postal code: 214422
2.0 Composition and details
Component, CAS number, Weight percentage
Phthalic anhydride, 552-30-7, 100%
(For exposure guidelines, see Section 8.0 “Exposure Control/Personal Protection”)
3.0 Hazard information
Overview of acute effects: Causes eye damage. Causes moderate skin irritation. It causes respiratory irritation. It can cause allergic respiratory reactions. Gastrointestinal irritation. Potential health effects: Contact with eyes: Harmful to the eyes. Contact with skin: Causes moderate skin irritation. Inhalation: Causes irritation of the respiratory tract. It can cause allergic respiratory reactions. When ingested: gastrointestinal irritation. HMIS Code: (Health: 3) (Flammability: 1) (Reactivity: 1) NFPA Code: (Health: 3) (Flammability: 1) (Reactivity: 1) 4.0 First Aid Measures Eyes: Flush immediately with plenty of water for at least 15 minutes, then seek medical attention right away. Skin: Wash the skin that came into contact with it using water and soap, remove the contaminated clothing, and ensure it is thoroughly washed and dried before use again. Seek medical attention if there are symptoms of irritation. Inhalation: Once swallowed, drink plenty of water. Induce vomiting only under a doctor's supervision. Seek medical attention immediately. Physicians note: Acute TMA asthma reactions should be treated in the same way as asthma caused by other factors. The initial assessment of the patient’s condition included measuring peak expiratory flow rate (PEFR) and forced expiratory volume in one second (FEV1). If both indicators exceed 80% of the expected value, treatment with only beta-receptor agonists is sufficient. If it is less than 80% or if the patient does not respond to treatment with β-receptor agonists alone, a complete blood count, chest X-ray, and arterial blood gas (ABGs) must be performed. If the patient develops cyanosis and acute dyspnea, oxygen therapy and the administration of systemic corticosteroids should be considered. The basic treatment for severe respiratory syndrome (TMA infection) is systemic corticosteroid therapy, with the use of bronchodilators if necessary. 5.0 Fire protection measures Ignition point: 440°F (220°C) Upper explosion limit: 7% Lower explosion limit: 1% Natural ignition temperature: Uncertain Flammability classification: None Extinguishing media: Agents suitable for extinguishing Class A fires (such as foam extinguishers, steam extinguishers) or water mist. Special fire and explosion hazards: High dust concentrations pose a potential risk of combustion and explosion. When there is a large amount of dust present, high-voltage electrostatic discharge and accumulation should be avoided. Firefighting equipment: Firefighters must be fully equipped, including self-provided positive-pressure oxygen supply devices. Prevention: Take preventive measures against static discharge, including ensuring complete connection between circuits, using grounded equipment, and transporting in an inert gas environment. 6.0 Measures to Avoid Accidents Vacuuming: To prevent dust from forming. Improve ventilation. 7.0 Operation and Storage Operation: Ensure adequate ventilation. Minimize the generation and accumulation of dust. Avoid static electricity buildup. Storage: Ensure adequate ventilation. 8.0 Exposure Control/Personal Protection Eyes: Do not get it in the eyes. Wear chemical goggles and a face shield. Skin: Avoid skin contact. Put on protective clothing and gloves. Breathing: Ensure adequate ventilation. If ventilation is insufficient, use a respirator that combines organic vapor filters with humor filters. Engineering controls: Keep the concentration in the air below the levels specified by the exposure guidelines. Guidelines for exposure exposure: Component CAS Number Exposure limit concentration Phthalic anhydride 552-30-7 OSHA PEL: 0.04 mg/m³ (1989) ； No standard established (1971). ACGIH limit: 0.04 mg/m³. 9.0 Chemical and physical properties: Appearance and odor: White. Flaky. Foul smell. PH: 2.0 Vapor pressure: less than 1.1*10 at 25°C Vapor density: 6.6 Boiling point: 730°F (390°C) Melting point: 330°F (165°C) Solubility in water: moderately soluble after acid hydrolysis. Specific gravity (water=1): 1.54
Reply to 3# jbcyf: Are there any available materials or standards related to trimellitic acid and phthalic acid? Thank you!