Market analysis and technical progress of the hott

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Market analysis and technical progress of acrylic acid

market analysis and technical progress of acrylic acid

August 30, 2005

as one of the important basic chemical raw materials, acrylic acid is mainly used to produce comonomers butyl acrylate and ethyl ester for water-soluble coatings and adhesives, as well as to produce super absorbent resins. Among them, the production of acrylate accounts for about 55% of the total demand. Glacial acrylic acid is used to produce super absorbent polymers (super absorbent resin, SAP), accounting for about 32% of the world's demand, as well as detergent polymers. A small amount is used in the production of polyacrylate as thickener, dispersant and rheological control agent. With the enrichment and development of downstream products, the worldwide acrylic acid production capacity is also increasing

in the production of acrylic acid, crude (unrefined) acrylic acid is almost used to produce acrylate (the most important are butyl ester, methyl ester, ethyl ester and 2-ethylhexyl ester), as well as other derivatives used in coating, papermaking, spinning, adhesives and ink industry. Except for a small amount of polyacrylate used as thickener, dispersant and rheological control agent, with the wide application of super absorbent resin in petroleum, chemical industry, light industry, construction, medicine, agriculture and other fields, glacial acrylic acid is mainly used to produce super absorbent polymer (super absorbent resin, SAP), accounting for about 32% of the world demand

world demand and production capacity

according to statistics, the global demand for acrylic acid was 2.4 million tons in 2000, and the global demand for acrylic acid stagnated in 2001, still 2.4 million tons. In 2002, the global consumption of acrylic acid increased to 2.6 million tons, of which sap and resin modifier accounted for 33% and 30% respectively. The total global production capacity in 2001 was 3.276 million T/year. In 2002, the world's acrylic acid production capacity reached 3.65 million T/year, of which 1.36 million T/year in North America, accounting for 37.3%, and 995000 T/year in Europe, accounting for 27.3%; Asia 1.295 million T/A, accounting for 35.4%. As of 2002, BASF, Rohm and Haas, Celanese, Japan catalytic synthesis and atofina were the top five acrylic acid producers in the world, accounting for 22.4%, 21.4%, 9.5%, 8.6% and 7% of the total global production capacity respectively. It is estimated that the world acrylic acid production capacity will reach 4.3 million T/A in 2005

although the annual growth rate of the world's acrylic acid consumption fell in 2001 and 2002, Tecnon orbitem predicts that the annual growth rate of the global acrylic acid consumption will reach 3.5% from 2003 to 2009. The total consumption of acrylate, super absorbent polymer (super absorbent resin) and polyacrylate will increase from 2.4 million tons in 1999 to 3.5 million tons in 2009. In 2002, the world consumption of acrylate was 2.3 million tons, and the annual growth rate of consumption is expected to be 3.6% from 2003 to 2009, which will reach nearly 3million tons in 2009. The consumption growth rate of developing countries and regions, especially China, will be greater than that of developed countries and regions

among the new global capabilities, BASF and Petrobras will jointly build acrylic acid and derivatives plants, with 65% and 35% shares respectively. The combined unit includes 160000 T/a acrylic acid, 120000 T/a glacial acrylic acid and 70000 T/a super absorbent polymer. Propylene raw material is supplied by the refinery. The device is scheduled to be put into operation in early 2004. Sasol company of South Africa and Mitsubishi Chemical Company jointly invested about US $200million in the construction of acrylic acid and acrylate combined plant in Sasol fort, South Africa. In the first stage, an 80000 T/a acrylic acid plant was built and 80000 T/a butyl acrylate and 35000 T/a ethyl acrylate were produced. It was put into operation in 2003. It is planned to double the acrylic acid capacity to 160000 T/A in the second stage, and build a 30000 T/a super absorbent resin plant at the same time

technical improvement

acrylic acid was first prepared by the reaction of vinyl ketone obtained from the thermal decomposition of acetone and acetic acid with formaldehyde, and then it was prepared from acetylene, water or ethanol and Co, but these processes were replaced by propylene gas-phase catalytic conversion method

the current process flow is as follows: the reaction raw materials containing propylene and steam are converted into acrolein and some acrylic acid, acetaldehyde and Cox under catalytic conditions. After condensing and separating acrylic acid, acrolein is further converted into acrylic acid, which can be absorbed and distilled to obtain crude acrylic acid (also known as esterification grade acrylic acid), and crude acrylic acid can be further refined to obtain high-purity acrylic acid and pure acrylic acid for polymerization

the moving bed process developed by DuPont is carried out under the condition of a small amount of oxygen or no molecular oxygen (lattice oxygen), which improves the selectivity of acrylic acid and reduces the amount of Cox by-products. However, because the rate of internal lattice oxygen dispersing to the catalyst surface is lower than the propylene oxidation rate, resulting in the lack of lattice oxygen on the catalyst surface, the catalyst selectivity is reduced, and the product yield is reduced. Therefore, in the case of no oxygen or low oxygen content, it is necessary to increase the propylene concentration in the reactant, the amount of catalyst, shorten the contact time between the material and the catalyst, so that the raw material can improve the product selectivity at a low conversion level. The development work of DuPont atofina Petrochemical Company focuses on the first step of acrylic acid production, that is, the gas-phase oxidation of propylene to acrolein. The traditional process focuses on the second step of further conversion of acrolein to acrylic acid, and the reaction conditions of this step are milder than that of propylene oxidation to acrolein. If the two steps are combined into one step, the yield of acrylic acid will be reduced due to the excessive oxidation of acrolein to carbon dioxide and other products. DuPont atofina's process is to pass propylene/steam/nitrogen by volume and bismuth molybdate catalyst through the lifting section of the moving bed reactor at a certain temperature and pressure. The catalyst circulation rate is 84kg/h, the contact time with feed gas is 2.4S, the one-way conversion is 75.7%, and the selectivity of acrolein and acrylic acid is 100%. The striking feature of moving bed reactor is that the reaction section of the system does not need to use air or oxygen. Instead, the reaction is carried out directly between propylene and catalyst oxygen, avoiding the non selective reaction between oxygen and propylene

in view of the fact that acrylic acid production requires two separate reactors, propylene oxidation to acrolein and acrolein oxidation to acrylic acid, Japan catalytic synthesis company has developed a single reaction system that can maintain the high yield of acrylic acid. A single fixed bed shell and tube heat exchange reactor is used, and the shell is divided into two independent spaces where the cold and hot media circulate separately. The reaction tube is filled with acrolein catalyst and acrylic acid catalyst from bottom to top, and inert substances are filled between the two catalysts. The mixture composed of 6% propylene, 60% air and 34% steam by volume passes through the reactor. The temperature of the lower part of the pipe is 325 ℃, and the temperature of the gas entering the upper part of the pipe is maintained at 265 ℃. The preliminary result of the reaction is that 89.5% acrylic acid is generated when the conversion of propylene is 97%

the two-stage fixed bed gas-phase oxidation process has been very mature, while new research and development are still being carried out in the improvement of catalyst performance, the increase of acrylic acid production and the optimization of reaction operating conditions. Due to the active chemical properties of propylene, it is necessary to limit the activity of the catalyst to an appropriate level, that is, to ease the reaction conditions, improve the product structure and extend the service life of the catalyst. BASF catalyst containing Mo, Bi and Fe oxide active components can achieve propylene conversion of 96.5% (V). Japan catalytic synthesis company launched a catalyst with molecular formula moacbacbdceof (a is Nb and W, B is Cr, Mg, Fe, Co, Zn, Bi, C is p, Sn, Ti, TE). By adjusting the proportion of a and B components in the catalyst, the catalytic activity can be changed. Therefore, using two active catalysts in a single tube reactor at the same time can convert higher concentrations of acrolein (5% (V) ~6.5% (V)) into acrylic acid in high yields (93%~94%). In addition, another key measure to improve the activity and prolong the service life of the catalyst is to control the reaction process and export the reaction heat in time, so as to prevent the product from adhering to the catalyst surface and coking and deactivation due to excessive reaction. BASF also proposed to divide the two-step reaction into two continuous reaction zones, and control the reaction temperature of the latter reaction zone to be higher than that of the former reaction zone, so as to meet the requirements of high load propylene and acrolein reaction. The reaction depth can also be optimized by adjusting the feed ratio of oxygen and propylene/acrolein in the raw material and the feed space velocity. In addition, the catalytic oxidation of propane, a cheap chemical raw material, to produce acrylic acid has also been widely carried out. For example, atofina takes propane/inert gas/steam with a volume ratio of 10~20:40~50:40~50 as the reaction raw material, and the composite oxide of mo-v-te-nb-si as the catalyst. The continuous reaction is carried out under the oxygen free condition of 0.05~0.5mpa. The conversion rate of propane is 22.2%, the yield of acrylic acid is 11%, and the yield of propylene is 3.9%

on the basis of digestion and absorption of imported technology, Shanghai Huayi acrylic acid company cooperates with Lanzhou Petrochemical Research Institute to independently develop propylene oxidation catalyst and build a 6000t/year industrial demonstration device. After the industrial test device of Shanghai Huayi acrylic acid company adopted the domestic catalyst developed by Lanzhou Petrochemical Research Institute, the load was increased from 100% to 125%, and the output was expanded to 8000t/year. Based on this technology, the company built a 30000 T/year acrylic acid device. The successful application of this technology has taken an important step for the localization of the catalyst. Up to now, 140000 tons of acrylic acid in China are produced by imported devices and catalysts every year. Compared with foreign catalysts in terms of reaction process, the catalyst has good activity, selectivity, high space velocity, low reaction temperature and bed resistance, which is conducive to the extension of the service life of the catalyst. Its catalyst technology and the level achieved are equal to those of similar international products, and at the same time, it has formed its own unique technical characteristics

current situation of Chinese market

in recent years, great changes have taken place in the production and market of China's acrylic acid industry. The output has soared from 96400 tons in 1996 to 139700 tons in 2001 and 142300 tons in 2002

the production of acrylic acid in China began in the 1960s. At that time, acrylonitrile hydrolysis was used in all units, with small scale and few varieties. In 1984, Beijing Dongfang Chemical plant introduced Japanese technology and equipment, and built and put into operation China's first large-scale acrylic acid and ester production plant. In the 1990s, Jilian (Jilin) chemical company and Shanghai Gaoqiao Petrochemical Company successively introduced Mitsubishi Chemical Technology from Japan and built two sets of units in 1992 and 1994 respectively. At the beginning of 2003, Gaoqiao Petrochemical Acrylic acid plant was built by Shanghai Huayi (Group) Company and acquired by releasing the monitoring index of China's ship capacity utilization, establishing Shanghai Huayi acrylic acid company. The propylene two-step oxidation method is adopted in the three main sets of acrylic acid and ester devices in China, which are not allowed to tighten the anchor nuts and start the experimental machine. In 2002, the production capacity of acrylic acid in China was 141000 T, and the unit operating rate reached 109.2%. Among them, the production capacity of high-purity acrylic acid unit is 33500 tons, the output is 18000 tons, and the operating rate of the unit is 53.7%. In the same year, the production capacity of acrylate (methyl ester, ethyl ester, butyl ester) was 233000 tons, and the operating rate of the unit reached 103. 0% of the general technical requirements. The above three enterprises are distributed in North China, Northeast China and East China, forming a tripartite pattern

in the early 1990s, the gap between supply and demand of domestic acrylic acid and ester increased year by year. So far, more than a dozen enterprises have prepared to build acrylic acid and ester projects. Shanghai Gaoqiao acrylic acid plant put into operation a 6000t/a acrylic acid plant at the beginning of 2003, using the domestic catalyst developed by the Research Institute of Lanzhou Petrochemical Company. The acrylic acid and ester projects under construction now include the Yangba integration project. The annual output capacity of the acrylic acid/ester unit is 16/215000 tons, and it is expected to be put into operation in 2005

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