Synthesis of Adipic Acid: On the Way to More Sustainable Production

Abstract

Adipic acid (AA) is an important chemical intermediate [1]. The production of Nylon-6,6 (for fibers and resins) accounts for 63% of AA consumption; the fibers are used in applications such as fishing lines, tires, carpets, home furnishings and in tough fabrics for parachutes, backpacks, luggage and business cases. Nylon engineering resins are chiefly used in electrical connectors, auto parts and items such as self-lubricating bearings, gears, and cams.The major non-nylon uses of AA are in polyester polyols (for polyurethane resins, 25% of AA production), in plasticizers (7%: dioctyl adipate, diisodecyl adipate, etc. for vinyl chloride, nitrocellulose and cellulose acetate polymers), resins (2%: unsaturated polyesters) and 3% for miscellaneous applications, such as a food ingredient in gelatins, and as a component in cosmetics, pharmaceuticals, fertilizers, paper, cements, waxes, and so on.Currently, the overall growth for AA is close to 3% per year, while demand is growing faster and is forecast to be around 5-6% per year by 2010. The expected growth is 12% in Asia-Pacific, around 8-9% in Asia/Middle East, while remaining stable in Western Europe and in the USA. The most rapidly growing sector is that of nylon resins, which has grown by 8-10% per year during the past decade. However, the market anticipates that the substitution of nylon engineering plastics into automobile parts is becoming saturated. Moreover, with 62% of the AA take, a slowdown in nylon fiber production is retarding the AA market. Nylon fibers are highly sensitive to the performance of the housing sector, which has been growing slowly for some years now, by about 1.7% on an annual basis. Nevertheless, despite the new plants being installed in China, capacity will fall short by 2010, because of the poor profitability that has hindered investments.In 2006, the global AA capacity was around 2.8 million metric tons per year; nearly 1 M-ton yr À1 was produced in Western Europe, 1 M-ton yr À1 in the USA (where 62% of the total global production is consumed), 0.5 M-ton yr À1 in Asia (excluding Japan), with the remainder being produced in Japan, Canada and Latin

Oxygenated commodity chemicals from chemo‐catalytic conversion of biomass derived heterocycles

“…1,6‐HDO is used as a feedstock to make polyester polyols and has a market price of $3000–4500/ton and volume of nearly 150 kton/yr . The petrochemical route for 1,6‐HDO production from benzene involves five reaction steps as shown in Scheme . Benzene is hydrogenated to cyclohexane over a metal catalyst and then oxidized to a mixture of cyclohexanol and cyclohexanone (“KA Oil”) over a homogeneous cobalt catalyst.…”

Catalytic selective oxidation faces the sustainability challenge: turning points, objectives reached, old approaches revisited and solutions still requiring further investigation

“…Examples of these 'nightmare reactions' include the ODH of propane to propene, 107 the oxidative coupling of methane to ethene and ethane, 108 the oxidation of isobutane to methacrylic acid, 109 the oxychlorination of ethane to 1,2-dichloroethane or vinyl chloride, and the one step AA synthesis. 76 This last reaction is indeed emblematic of the various approaches that can be used in developing a more sustainable alternative to the industrial technologies currently being used. As mentioned above, the industrial process used for AA production is the oxidation with nitric acid of either a mixture of cyclohexanol and cyclohexanone (the so-called KA oil), or of cyclohexanol.…”

“…9 In AA synthesis, the oxidation of the KA oil is performed using 50-65% HNO 3 as an oxidant and with a homogeneous Cu/V catalyst. 4,76 The nitric acid is reduced to a mixture of N 2 O, NO and NO 2 ; the major environmental concern is the emission of nitrous oxide. The amount produced is around 300 kg N 2 O ton −1 AA; N 2 O, due to its strong IR absorption, is believed to contribute to the greenhouse effect and global warming, which is made worse by the fact that the estimated atmospheric lifetime of N 2 O is about 150 years.…”

Production of medium-chain, a, omega-bifunctional monomers from fatty acids and n-alkanes

“…This mixture is treated with nitric acid, to yield AA, see Figure 1.2. The treatment with nitric acid results in release of nitrous oxide 5 , a gas that has a global warming potential of about 290 times more than CO2 6 . As a result, AA production results in the emission of large quantities of greenhouse gas, ≥4 ton CO2-equivalent per ton AA 7,8 .…”

“…To produce AA, benzene is converted into a mixture of cyclohexanol and cyclohexanone. This mixture is oxidized with nitric acid to yield adipic acid with the concomitant emission of N2O, a potent greenhouse gas 2,5 C8-C10 DCAs are produced from renewable feedstocks, such as oleic acid and ricinoleic acid, via ozonolysis 16,101 . Although ozonolysis of unsaturated fatty acids is highly selective and effective, it suffers from several drawbacks.…”