1、 Industrial production method of epichlorohydrin

 

At present, there are three main industrial production methods of epichlorohydrin: propylene high temperature chlorination method, acetic acid propylene vinegar method and glycerol method.

 

1. Propylene high temperature chlorination

 

Propylene high temperature chlorination method was first developed by shell company in 1948 and applied to industrial production. The process mainly includes three reaction units: high temperature chlorination of propylene to chloropropene, hypochlorization of chloropropene to dichloropropanol, saponification of dichloropropanol to epichlorohydrin. Propylene high temperature chlorination process is characterized by flexible production process, mature process and stable operation. In addition to producing epichlorohydrin, it can also produce important organic synthesis intermediates such as glycerol and chloropropene. The by-product D and D mixture (1,3-dichloropropene and 1,2-dichloropropane) is also an important intermediate for the synthesis of pesticides. The disadvantages are high requirements for propylene purity, high energy consumption, high chlorine consumption, many by-products, large amount of wastewater and difficult treatment, easy corrosion of equipment and low product yield. The investment in the treatment of three wastes is large, and the production cost of epichlorohydrin is high.

 

2. Allyl acetate process

 

The former Soviet Academy of Sciences and Showa electric company of Japan have successfully developed propylene acetate method respectively. The main raw materials of the method are propylene, oxygen, acetic acid, chlorine and lime. The main process includes four steps: gas phase catalytic oxidation of propylene and acetic acid to produce propylene acetate, hydrolysis of propylene acetate to acetic acid to produce allyl alcohol, addition of allyl alcohol and chlorine to synthesize dichloropropanol, and saponification of dichloropropanol to produce epichlorohydrin. The method is characterized by adopting acetyl oxidation technology, high yield, chlorine free alcoholization reaction and high product quality; No high temperature chlorination process, mild reaction conditions and less by-products; The consumption of chlorine and lime is small. The main disadvantages are: long process flow, short catalyst life, stainless steel material resistant to acetic acid corrosion, mixture explosion of allyl alcohol unit must be prevented, relatively high investment, difficulty in wastewater treatment, etc.

 

3. Glycerol method

 

Epichlorohydrin was originally the raw material for the production of glycerol. However, with the change of glycerol price and the substantial increase of demand for epichlorohydrin in the production of epoxy resin, the price of epichlorohydrin is higher than that of glycerol. From an economic point of view, epichlorohydrin is no longer suitable for the production of glycerol. In recent years, due to the high price of crude oil, countries have made great efforts to develop biodiesel industry, and the technology of producing epichlorohydrin with glycerol, a by-product of biodiesel, has attracted renewed attention. Solvay of Belgium has developed epicero process for producing epichlorohydrin from glycerol. With the help of a proprietary catalyst, the intermediate dichloropropanol is prepared by one-step reaction of glycerol and hydrogen chloride without the use of chlorine. In addition, the process produces a very small amount of chlorination by-products, and the water consumption and wastewater are also small. Solvay built a 10000 t / a epichlorohydrin industrial production unit using this process in tavaux production base in France in 2007, which is also the first industrial application of this process. The glycerol process developed by Jiangsu Institute of technology has the following advantages: no propylene consumption: safe and reliable, no chlorine and hypochlorous acid; Low investment, only 1 / 4 of propylene high-temperature chlorination method: low cost, 3000 yuan / t lower than propylene high-temperature chlorination method; The operating conditions are loose and the pollution is greatly reduced. The amount of wastewater is 1 / 10 of that of propylene high-temperature chlorination method: no expensive catalyst is required. Dow Chemical Co., Ltd. and Jiangsu Yangnong Chemical Co., Ltd. have built an industrial production plant of glycerol epichlorohydrin.

 

The main raw materials for producing epichlorohydrin by glycerol method are industrial glycerol, 30% caustic soda and hydrogen chloride gas. There are two main steps: glycerol reacts with dry hydrogen chloride in the presence of catalyst to produce dichloropropanol, which is saponified in alkaline solution to obtain epichlorohydrin. The production process can be divided into continuous method and intermittent method. The continuous method is to prepare epichlorohydrin by saponification of the reaction solution obtained by chlorination of glycerol without treatment; The intermittent rule is that after chlorination of glycerol, alkali is added to the reaction solution to neutralize the excess hydrogen chloride, dichloropropanol is obtained by vacuum distillation, and then saponification reaction is carried out. The continuous method is simple and easy to operate. However, due to the lack of treatment of chlorinated products, excessive alkali liquor is required during saponification, and there are many by-products, which can not be well separated, which has a certain impact on the purification of saponified products. Although the operation of batch method is more complex than that of continuous method, it can make full use of raw materials, Unreacted glycerol and monochlorinated products can continue to be used to produce dichloropropanol.

 

4. Comparison of main technical indexes

 

Comparison of main technical indexes of different production processes of epichlorohydrin

 

It can be seen from the above table that the process of producing epichlorohydrin by glycerol method has the following advantages: (1) short process flow and less investment. (2) Glycerol method does not need expensive catalyst and has low production cost. (3) Glycerol process has the advantages of less by-products, low waste treatment cost, greatly reduced pollution and friendly to the environment. (4) The whole production process only consumes gas HCl, does not need to directly consume chlorine or hypochlorous acid, has no high temperature and high pressure, and the operating conditions are relatively mild, safe and reliable. (5) Glycerol method does not consume propylene, has rich raw material resources, can also be regenerated, is easy to form circular economy, and has obvious economic benefits. Disadvantages: the price of raw glycerol has a great impact on the cost. The biodiesel market is restricted by the biodiesel market. At present, the global food price is rising, and the development of biodiesel remains to be discussed. Therefore, the development of glycerol method depends on the development of biodiesel.

 

2、 Supply and demand situation and development prospect of epichlorohydrin in the world

 

1. Production status

 

In recent years, the rapid growth of epoxy resin demand has promoted the development of epichlorohydrin. In 2008, the total production capacity of epichlorohydrin in the world reached about 1808000 T / A, including 460000 T / A in North America, accounting for about 25.6%; Western Europe is 287000 T / A, accounting for about 15.9%; central and Eastern Europe is 196000 T / A, accounting for about 10.9%; Asia is 857000 T / A, accounting for about 47.6%. At present, the production of epichlorohydrin in the world mainly presents three characteristics. (1) the production and the development of the country are few and uneven. The total production capacity of China, the United States, Germany, Russia, Japan and China in Taiwan reaches 1 million 544 thousand t/a, accounting for 85.8% of the world's total production capacity. The top 5 producers are Dow Chemical Company, Hexion specialty chemicals company, China Shandong Haili chemical industry Limited (Bo Hui) company, China Taiwan Formosa Plastics Corp and sol Wei company. Dow Chemical has a production capacity of 480000 T / A in the United States and Germany, accounting for about 26.7% of the world's total production capacity; Hexion special chemical crystal has a production capacity of 175000 T / A, accounting for about 9.7% in the United States and the Netherlands; China Shandong Haili Chemical Co., Ltd. (Bohui) has a production capacity of 160000 T / A, About 8.9%: Formosa Plastics Corp of Taiwan, China, has a capacity of 100 thousand t/a, or about 5.6%: the production capacity of the company is 92 thousand t/a, accounting for 5.1%. The process route is relatively simple, and most units adopt propylene high-temperature chlorination method. Asia's production capacity has increased rapidly in recent years. In particular, China's production capacity has reached 531000 T / A, accounting for about 29.5% of the world's total production capacity. China has surpassed the United States to become the world's largest producer of epichlorohydrin.

 

With the continuous operation of the newly-built and expanded epichlorohydrin unit in China and the epichlorohydrin unit built by Solvay in Thailand, it is expected that the total production capacity of epichlorohydrin in the world will exceed 2.3 million T / a by 2012.

 

2. Consumption status and development prospect

 

In 2007, the world's total consumption of epichlorohydrin was about 1.12 million tons. North America, Western Europe and Asia were the main consumption areas, accounting for about 20.8%, 22.9% and 53.6% of the world's total consumption respectively. Epichlorohydrin is mainly used to produce epoxy resin and synthetic glycerol. The consumption of epoxy resin accounts for about 82.1% of the total consumption, glycerol accounts for about 4.0%, and other aspects (including elastomer, polyamide epichlorohydrin resin, glycidyl ether, surfactant, flame retardant and quaternary ammonium salt) account for about 13.9%. It is estimated that in the next few years, the world demand for epichlorohydrin will increase at an average annual rate of about 6.0%, and the total demand will reach about 1.5 million tons by 2012. The average annual growth rate of demand in the United States and Western Europe is 2.0% - 2.5%, while the average annual growth rate of demand in Asia will reach about 12.0%.

 

Consumption of epichlorohydrin in major consumption areas in the world in 2007

 

3、 Supply and demand situation and development prospect of epichlorohydrin in China

 

l. Production status

 

The production of epichlorohydrin in China began in the 1960s. In the past two years, due to the increasing demand for epoxy resin, etc., the development prospect of epichlorohydrin in China is promising. Therefore, many enterprises build or expand epichlorohydrin production units. As of May 2009, China's production capacity has reached 611000 T / A.

 

With the continuous increase of production capacity, the output of epichlorohydrin in China is also increasing. It was only 60000 t in 2002, increased to 120000 t in 2006, and further increased to about 279000 t in 2007, with a year-on-year increase of about 136.4%. The average annual growth rate from 2002 to 2007 was about 36.0%.

 

2. Proposed new construction

 

Due to strong downstream market demand in the early stage, tight domestic supply and large product profits, many domestic enterprises are still building or planning to build epichlorohydrin units.

 

It is predicted that the total production capacity of epichlorohydrin in China will exceed 1.2 million T / a by 2012, and the production capacity will be seriously surplus at that time.

 

Main manufacturers of epichlorohydrin in China in 2009

 

3. Import and export

 

In recent years, due to the strong demand for epichlorohydrin such as epoxy resin and synthetic glycerol, the demand for epichlorohydrin in China has increased rapidly, but the current output can not meet the domestic demand and has to be imported every year. In 2000, the import volume was 25400 T, reaching 110900 t in 2005. The average annual growth rate from 2000 to 2005 was about 34.28%, and increased to 145400 t in 2006, a record high. In 2007, the domestic output increased rapidly, and the import volume decreased to 80200 T, a year-on-year decrease of about 44.84%; in 2008, the import volume was 64500 T, a year-on-year decrease of 19.60%. The imported products mainly come from the United States, Russia and Taiwan, accounting for about 65.0% of the total imports. At the same time of import, China also exports a certain amount of epichlorohydrin every year, which was 038000 t in 2000, 074000 t in 2006, 6600 t in 2007 and 6900 t in 2008, with a year-on-year increase of about 4.5%.

 

4. Consumption status and development prospect

 

In recent years, the apparent consumption of epichlorohydrin in China is increasing.  In 1995, it was only 25900 tons, and in 2000, it reached 65500 tons. The average annual growth rate in 2000 was 20.4%: it reached 10.357jt in 2002, increased to about 352600 t in 2007, with a year-on-year increase of about 34.2%, and the average annual growth rate from 2002 to 2007 reached about 27.8%. The self-sufficiency rate of domestic products also increased from 57.9% in 2002 to about 79.13% in 2007. The supply and demand of epichlorohydrin in China in recent years is shown in the table below.

 

Supply and demand of epichlorohydrin in China in recent years

 

At present, epichlorohydrin in China is mainly used to produce epoxy resin, accounting for about 90% of the total consumption, followed by synthetic glycerol, 4%, chlorohydrin rubber and 4% in other fields. Due to the single consumption field of epichlorohydrin in China, the growth of epoxy resin demand has become the main driving force to promote the development of epichlorohydrin.

 

At present, the domestic demand for epoxy resin is still growing at a rapid rate. Despite the rapid growth of production capacity in recent years, it is still unable to meet the demand and needs to be imported in large quantities every year. From 2005 to 2008, the net import volume of epoxy resin was 182000 T, 182000 T, 175000 T and 134000 t respectively. 2008 is the low tide year of epoxy resin market. In 2007, the production capacity expanded significantly, the output increased significantly, and the rapid growth exceeded the actual demand, which buried the hidden danger of oversupply in the epoxy resin Market in 2008, and the market situation in 2009 will be more severe. The epoxy resin market has been declining all the way, and the market can still be maintained in early 2008. Although the traditional peak season comes after the Spring Festival, the market has not improved, and the trading is not warm and hot Prices have gradually declined;  During the Olympic Games, the market gradually weakened due to relevant regulations; At the end of the year, with the spread of the global financial crisis, the epoxy resin market suffered a heavy setback. The price of epoxy resin in East China has plummeted. The liquid resin has decreased from 28000 yuan / T to 15000 yuan / T, and the solid resin has decreased from 23000 yuan / T to 10000 yuan / T, with a decline rate of more than 60%, reaching the lowest level in five years. The utilization rate of the production capacity of the unit has also been compressed below the average level of 50%, especially the record low of 30% of liquid resin and 20% of solid resin in October. In 2008, the shadow of oversupply began to envelop the market. Most of the newly-built and expanded units operated at low load or postponed the formal operation time. After the outbreak of the global financial crisis, many liquid resins stopped and reduced production; Solid resin is produced intermittently and flexibly, and the overall start-up is still 45%. Export orders decreased and domestic demand shrank. Due to the financial crisis, the economic recession and the decline of consumption capacity in Europe and the United States, the export of epoxy resin suffered a cold current and orders decreased significantly. According to customs statistics, China's epoxy resin export has been at a very low level since September 2008. Among them, the export volume from September to November has decreased by 25.5%, 43.4% and 64.7% respectively compared with the high level in the previous eight months. However, at the time of the spread of foreign aggression, domestic worries have arisen again. The demand in the domestic downstream coating, electronic and electrical, automotive and construction fields has decreased sharply, resulting in a sharp increase in the inventory of manufacturers. In 2009, the epoxy resin market will continue the situation in 2008, and may even become more severe. The production capacity of epichlorohydrin continues to increase, which will inevitably lead to oversupply, reduce the operating rate of manufacturers and continue to decline the price.

 

5. Price trend

 

From 2006 to 2009, the domestic market price of epichlorohydrin completed the conversion from a record high to a fluctuation near the cost line. In 2006, with the rapid development of national economy, the demand for epoxy resin entered another round of rapid growth. When the domestic epichlorohydrin supply accounted for less than 40% of the demand, the unexpected shutdown of a domestic plant led to the breaking of the balance between supply and demand. At the beginning of the second quarter, the highest market price rushed to the historical high of 26500 yuan / T. Since the epichlorohydrin anti-dumping case was filed, the domestic epichlorohydrin market price has increased continuously. June 2006