Information on the current production status and market analysis of acetic anhydride

(CH3CO)2O is also known as acetic anhydride or acetone anhydride. It is mainly produced from acetaldehyde, methanol, etc. A colorless, transparent liquid with an irritating odor and tear-inducing properties; its boiling point is 138.63°C. Its vapors can form explosive mixtures with air, with an explosion limit of 0.9% to 10.3%. It is widely used as an acetylating agent, dehydrating agent, and solvent in the production of cellulose acetate, pharmaceuticals (such as streptomycin, dibazol, aspirin), as well as dyes and fragrances. 　　In 1852, C.-F. Gerbal in France first prepared acetic anhydride by reacting benzoyl chloride with potassium acetate; later, it was synthesized using phosphorus oxychloride and potassium acetate. During World War I, it was produced using thionyl chloride and sulfuryl chloride. After 1920, the ene synthesis method and acetaldehyde oxidation method were commonly used for production. In the 1980s, a new process was developed to convert methanol into methyl acetate and then carry out carbonylation (see carbonyl synthesis) to produce acetic anhydride. In 1983, Eastman Chemical Company in Tennessee, USA, was the first to build a plant using this process, with an annual production capacity of 2.1 Mt of acetic anhydride. 　　The ethylene method involves using propylene or acetic acid as raw materials; first, thermal decomposition is carried out to produce the intermediate ethylene, which is then cooled and chemically absorbed in two series-connected packed towers using a circulating liquid (a mixture of acetic acid and acetic anhydride), thereby producing acetic anhydride: H2C≡C≡O + CH3COOH → (CH3CO)2O. To prevent the formation of diethylene, which has a boiling point similar to that of acetic anhydride (127.4°C), the absorption process is conducted at temperatures of 30–40°C and pressures of 6.6–19.7 kPa. Sometimes, a small amount of oxidant is added to prevent the formation of diethylene. The resulting product is absorbed and continuously distilled in three columns to obtain acetic anhydride with a purity of over 95%. This method involves many production steps, consumes a large amount of energy, and the overall yield of acetic anhydride is only about 70%; it is therefore an outdated approach. 　　Acetaldehyde oxidation method: In an acetic acid medium, using oxygen or air as an oxidant, and in the presence of a copper acetate-cobalt acetate catalyst, acetaldehyde is oxidized to acetic anhydride at temperatures of 45–60°C and pressures of 100–300 kPa. The reaction equations are as follows:
　　　　 CH3CHO + O2 → CH3COOOH　　　　　　 (1)
　　　　 CH3COOOH + CH3CHO → (CH3CO)2O + H2O　　　 (2)
　　　　 (CH3CO)2O + H2O → 2CH3COOH　　　　　 (3)
The key to obtaining high yields of acetic anhydride is to inhibit the occurrence of reaction (3). In industrial production, water removal agents such as ethyl acetate can be used to rapidly evaporate water from the reaction system in order to reduce the hydrolysis of acetic anhydride. This method is simple to operate and produces acetic acid as a by-product; it is currently the main method for producing acetic anhydride. 　　Methyl acetate carbonylation method: This process uses methanol and acetic acid as raw materials, a rhodium-based catalyst (see complex catalysts) and a chromium compound as a co-catalyst to carry out carbonylation to produce acetic anhydride. The main reactions are: CH3OH+CH3COOH → CH3COOCH3+H2O; CH3COOCH3+CO → (CH3CO)2O; CH3OH+CO → CH3COOH. Industrially, this process is carried out in two steps: the first step is the esterification of methanol to form methyl acetate ； The second step is the carbonylation of methyl acetate to acetic anhydride, at a temperature of 175°C and a pressure of 25 MPa; the selectivity for the formation of acetic anhydride is 95%. The development of this process is regarded as one of the achievements in carbon-one chemistry, attracting attention from various countries.

There is relevant information in the database; you might as well give it a search.

In 2006, China’s acetic anhydride production capacity was 123,000 tons per year, with a production volume of 103,000 tons； If acetic anhydride, which is an intermediate product for cellulose acetate (acetate sheets), is included, the production capacity for acetic anhydride is 203,000 tons per year, with a production volume of around 183,000 tons. At present, the production of acetic anhydride in China is mainly concentrated in three companies: Nantong Acetate Fiber Company, Jilin Petrochemical Company, and Jiangsu Danyang Chemical Group Co., Ltd. Jilin Petrochemical Company used to be a leader among acetanilide producers in China; after three rounds of expansion and renovation, its current production capacity amounts to 60,000 tons per year. Jiangsu Danyang Chemical Company uses the methanol carbonylation method to produce acetic anhydride. Thanks to its advantages such as a short production process, high product quality, low consumption levels, reduced emissions of waste materials, and low costs, this method has seen rapid development over the past two years. In 2004, the company’s capacity for producing acetic anhydride was 10,000 tons per year; by 2006 it had increased to 28,000 tons per year, and in 2007 the production capacity was further raised to 80,000 tons per year, making it the largest acetic anhydride producer in China. Nantong Acetate Fiber Company is a joint venture between China National Tobacco Corporation and the American company Celanese. In 2006, its acetic anhydride production capacity was 80,000 tons per year; the acetic anhydride produced by this company is used entirely as raw material for manufacturing acetate fiber within the same company, and no amount of it is sold on the market. After building a 600,000 t/a acetic acid plant in Nanshan, Serranus will construct a 100,000 t/a acetic anhydride plant alongside it, with completion and operation expected in 2009. Our country is the largest producer and consumer of cigarettes in the world, ranking first globally in cigarette production, with a consumption of cellulose acetate exceeding 160,000 tons. From 2000 to 2004, China imported approximately 10,000 tons of unplasticized cellulose acetate; this figure rose sharply to 65,000 tons in 2005, and 77,000 tons were imported in 2006. It can be said that cigarette filters will represent the most promising market for acetic anhydride in our country in the future; it is estimated that the demand for acetic anhydride for cigarette fibers will reach 250,000 tons by 2010.

May I ask what manufacturing processes are currently used for acetic anhydride in China? What are the processes for acetic anhydride? What are the features?

Currently, the main industrial methods for producing acetic anhydride are the oxidation of acetaldehyde, the ethylene method, and the carbonylation of methyl acetate. The ethylene method and the methyl acetate carbonylation method are currently the most commonly used approaches for producing acetic anhydride. Among them, the acetic acid cleavage method for producing acetic anhydride requires large investment, incurs high costs for raw materials and utility consumption, resulting in higher production costs. For an acetanhydride production facility of the same scale (with an annual output of 227,000 tons), the investment required for the acetic acid pyrolysis method is 163 million dollars, whereas it is 96 million dollars for the methyl acetate carbonylation method – which is only 60% of the cost associated with the acetic acid pyrolysis method, and 68% of the net production cost. Although the main method for producing acetic anhydride remains the pyrolysis of acetic acid at present, the high pyrolysis temperature of around 750°C in this method easily leads to carbon deposition in the reaction tubes, causing blockages, and it is also energy-intensive; therefore, it will surely be replaced in the future by the methyl acetate carbonylation method. With the continuous development and application of carbonylation catalysts, carbonylation technology is bound to **make progress. Both the investment in equipment and production costs will decrease, and the synthesis of acetic anhydride using the carbonyl method will become the main approach for its production. In 2006, there were over 10 manufacturers of acetic anhydride in China, with a total production capacity of approximately 310,000 tons per year. The actual output was around 188,000 tons per year. The main manufacturers included PetroChina Jilin Petrochemical Company (with a production capacity of 100,000 tons per year, using the acetic acid pyrolysis method), Shanghai Chemical Reagents Factory (with a capacity of 17,000 tons per year, using the acetaldehyde oxidation method), Jiangsu Danhua Group Acetic Anhydride Co., Ltd. (with a capacity of 80,000 tons per year, using the methyl acetate carbonylation method), Jiangsu Nantong Acetate Fiber Company (with a capacity of 80,000 tons per year, using the acetic acid pyrolysis method), Jiangsu Nantong Acetic Acid Chemical Co., Ltd. (with a capacity of 10,000 tons per year, using the acetic acid pyrolysis method), Nanjing Acetic Acid Factory (with a capacity of 5,000 tons per year, using the acetic acid pyrolysis method), and Shandong Xinhua Pharmaceutical Group Company (with a capacity of 35,000 tons per year, using the acetic acid pyrolysis method).

There are two processes for acetic anhydride production in China: the acetic acid cracking method and the carbonyl synthesis method. The former is represented mainly by Jihua Company, but this technology requires large investments and high consumption levels； The latter is represented by Jiangsu Danhua Group; in fact, there is no second domestic manufacturer that uses this production technology. Those who are interested might as well search on the company’s website! ! 1

During the continuous production of acetic anhydride by the carbonylation process, raw materials methanol and acetic acid (HAc) are continuously fed into esterifier 1; the resulting methyl acetate, along with the purified gas from the carbon monoxide section, is then fed into carbonylation reactor 3. The temperature is raised to the specified reaction temperature, and the reaction takes place under the action of a catalyst. The reaction mixture coming out of carbonylation tower 3 is sent to flasher 4, where the vaporized gas is condensed and then sent to dehydrogenation tower 7, allowing for the recovery of most of the methyl iodide as well as the unreacted methyl acetate ； The gaseous emissions that cannot be condensed into a liquid are passed through the exhaust gas scrubber tower 10, where CO, a small amount of iodides, and methyl acetate are recovered for reuse. The mother liquor at the bottom of the flasher, along with the iodomethane and methyl acetate from the distillates of the dehydrogenation tower, are sent back to the carbonylation reactor for reuse. The bottom liquid from the dehydrogenation tower is sent to the anhydride separation tower 8, where the acetic acid product is separated out; the bottom liquid is then sent to the vacuum distillation tower 9 for further distillation, thereby yielding the acetic anhydride product.

Anhydrides are now considered to be chemicals that can be easily used to manufacture drugs, right? We carried out nitration reactions for a factory; originally, anhydrides worked very well for this purpose. But now due to regulations, they plan to switch to other methods. It’s hard to say what the future holds for these products

Shandong Jin Yimeng’s 150,000 tons per year carbonylation acetic anhydride plant will come online in September this year

Take a look here; this article provides a fairly comprehensive overview of acetic anhydride, and you can download it for later use. http://bbs.hcbbs.com/viewthread.php?tid=150001&highlight=%2B%B4%D7%F4%FB