Adipic Acid SWOSU ICER98 submitted 2/23/98 Bart Barnett, Bill McKinley, Darren Toczko, Kevin Worley Adipic acid is one of the most used chemicals in the world today, conversly, it contributes significantly to the production of nitrous oxides (NOx), a greenhouse gas. Many methods are available to produce adipic acid, with various results and potential for pollution. The following paper discusses the impacts that adipic acid has on our society and the world’s environment. At the end of the paper, is a list of some of the sources used for this topic. Any disagreements between the various sections of this article probably resulted from this being a group effort.
Uses Adipic acid is a very important chemical that is used all over the world to produce various products that people use every day. Nylon 6.6, foams, paints and tires are just a few of the products that are formed by the use of adipic acid (AAD). Adipic acid is also used as a food ingredient in gelatins, desserts and other foods that require acidulation. Nylon 6.6 is the largest outlet for adipic acid, accounting for more than 89% of the total consumption in North America. One of the leading producers, BASF, produces 70 million pounds of nylon per year. Nylon is used for everyday applications such as electrical connectors, cable tires, fishing line, fabrics, carpeting, and many other useful products.
Production The consumption and production for adipic acid is dominated by the United States. Of the 2.3 million metric tons of adipic acid produced worldwide, 42% is produced in the United State while the United State consumes 62% of total production. Western Europe produces the majority of the remaining adipic acid with 40%, and 13% in Asia-Pacific, while the other regions account for the remaining 5%. The process of producing adipic acid can be done by using different reactions. The main reaction is by the oxidation of cyclohexane into cyclohexanol and cyclohexanone.
Another industry reaction is by the hydrogenation of benzene into cyclohexane and then oxidation. Adipic acid can be produced from butadiene by carboalkoxylation, but this process is not commercialized. The production of adipic acid through the oxidation of cyclohexane is done by reacting cyclohexane with oxygen for air in the presents of a catalyze of cobalt or manganese at a temperature of 150?C to 160?C. This reaction forms a mixture of the cyclohexanol and cyclohexanone. The products are distilled to remove the unreacted cyclohexane which is recycled.
The cyclohexanol and cyclohexanone are then reacted with nitric acid and air with a copper and vanadium catalyst. In this reaction, air is the oxidation reactant that produces the adipic acid. This reaction produces almost all of the world’s adipic acid. There are variations of this reaction’s first step producing cyclohexanone and cyclohexanol from cyclohexane. This includes the using of Boron oxide hydroxide and oxygen, or by oxygen and a catalysis to form the intermediate cyclohexyl hydroperoxide with further reaction with catalytic amounts of transition metals.
The second step also can be done by reacting cyclohexanol and cyclohexanone with only air and catalytic amounts Cobalt, copper, and manganese. This non-nitric acid process has the advantages of no risk of corrosion and no NOx are produced. The disadvantage is that succinic acid and glutartic acid is formed with the adipic acid, thus making purification a problem. Phenol can be substituted for cyclohexane. This involves the hydrogenation on the phenol into cyclohexanol with elemental hydrogen and a catalysis. From the cyclohexanol, nitric acid is used to form the adipic acid.
The process of production of adipic acid from benzene is commercially used, but does not account for a major amount of the total production. This reaction, starting with benzene, produces cyclohexane as an intermediate step. Then the reaction continues, as in the cyclohexane path of reaction. The change of the benzene to cyclohexane is done by simply hydrogenation of the benzene. The benzene can also be change into phenol, and the reaction process that pathway. The production of adipic acid with carboalkoxylation of butadiene is new and only in the experimental stage, but may hold promise for a less expense production.
Many alternate processes have been researched; but so far, the oxidation of cyclohexane with nitric acid is the most efficient. So in turn, it is the most used. Summary of reactions Environmental Effects The adipic acid industry has a detrimental impact on the environment by letting out an enormous amount of greenhouse gas. Estimated current global production of adipic acid is at 1.8 million metric tons per year. The largest use is to make the common product nylon.
The greenhouse gas is specifically N2O. The N2O is produced during two oxidization steps in the production of adipic acid. The large amount of adipic acid production per year, due to the common product that it produces, has led to an enormous amount of this greenhouse gas to be emitted. There are several specific facts about why N2O is so bad for the environment. First, N2O is a radioactively and chemically active trace gas believed to contribute to the recent increase in the Earth’s surface temperature.
N2O absorbs reflected infrared radiation. Also, estimated atmospheric lifetime of N2O is 150 years. Last, the estimated impact of anthrogenic N2O is a 6% increase in ozone depletion rate. N2O from the production of adipic acid is harmful to the environment because of its heat absorbing and ozone depleting qualities. Producers have recognized N2O production as making a measurable contribution to global warming and ozone depletion. Manufacturers of adipic acid are attempting to reduce emmisions by forming inter-industry groups, which share information, and the use of different technologies.
They have come up with three technology options. The first option is improvement for N2O decomposition in special designed boilers. The second option is conversion of N2O to recoverable NO. The third option is the catalytic dissociation of N2O to N2 and O2. References: Bill’s part.
(Production Section) Y.R Chin, PEP abstract: Adipic acid, September 1996.Copyright 1998 SRI consulting. http://piglet.sri.com/CIN/NovemberDecember96/Artic le11.html Authors: A. Castellan, J.C.J. Bart and S. Cavalllaro Journal: Catalysis Today, 9 (1991) pg. 237-254 Title of article: Industrial Production and Uses of Adipic Acid.
Darren’s part (Environmental Section) Authors: R.A. Reimer, C.S. Slaten, M. Seapan, M.W. Lower, and P.E.Tomlinson Journal: Environmental Progress, vol 13, No.2, May 1994. Title of article: Abatement of N2O Emissions Produced in the adipic acid industry Environmental Issues.