General Adipic Acid Production Adipic acid has been synthesized in commercial quantities for about 50 years.1 The process to make adipic acid was first created by Dupont in the 1940s.2 In general, the production of adipic acid combines two steps. These two steps include the oxidation of cyclohexane to a mixture cyclohexanol and cyclohexanone followed by the oxidation of this mixture to produce adipic acid (see Figure 1).1 Through the years, many variations on this basic process were discovered and used industrially because of improvements they may have made to the product yield, waste production or manufacturing cost.
Figure 1: The first step of adipic acid production is the oxidation of cyclohexane to produce cyclohexanol and cyclohexanone. …show more content…
3 This reaction occurs in a series of stirred tank reactors containing cyclohexane and the catalyst is injected into these tanks using an air stream.4 This first step of the reaction is run at low conversion because these reaction conditions select for the ketone, alcohol and cyclohexylhydroperoxide products.3 Any unreacted cyclohexane is recovered through distillation and recycled. As a result of being run at low conversion, this step is energy intensive. Some techniques that have been discovered to save energy in this step are process-process heat interchange, and high efficiency packed distillation columns. The crude KA oil is purified by contacting the KA oil with water or a solution of caustic soda to remove mono- and dibasic acid impurities.3 This technique to remove impurities is also used to save energy since it removes the final steam stripper, which is an energy intensive step.5 Moreover, the final steam stripper produces the most hazardous wastes. These wastes consist of nonvolatile by-products, metals and residues from catalysts, which are all burned in order to eliminate the wastes and produce steam to heat the oxidation process.3 Waste is generated during the oxidation and the separation step of this reaction, which must …show more content…
The CHHP can be produced in high yield and can then be converted to KA oil in a high yield. CHHP is converted to KA oil by decomposing the CHHP with homogeneous or heterogenous catalysts containing Co, Cr, Mo, V, Cu, or Ru.6 Another method to convert CHHP to KA oil is by dehydrating the CHHP with caustic soda or by dehydrogenating it. Using caustic soda in the dehydration produces more ketone products in the KA oil, while dehydrogenating the CHHP produces more alcohol products in the KA oil.3 In order to get a high yield (as high as 75%) of CHHP, companies use methods including: eliminating metal catalysts in the oxidation step, minimizing cyclohexane conversion, passivating reactor walls, lowering the reaction temperature, adding water to the reaction mix to extract acid catalysts from the cyclohexane phase, and adding metal-chelating agents to the reaction
Figure 1: The first step of adipic acid production is the oxidation of cyclohexane to produce cyclohexanol and cyclohexanone. …show more content…
3 This reaction occurs in a series of stirred tank reactors containing cyclohexane and the catalyst is injected into these tanks using an air stream.4 This first step of the reaction is run at low conversion because these reaction conditions select for the ketone, alcohol and cyclohexylhydroperoxide products.3 Any unreacted cyclohexane is recovered through distillation and recycled. As a result of being run at low conversion, this step is energy intensive. Some techniques that have been discovered to save energy in this step are process-process heat interchange, and high efficiency packed distillation columns. The crude KA oil is purified by contacting the KA oil with water or a solution of caustic soda to remove mono- and dibasic acid impurities.3 This technique to remove impurities is also used to save energy since it removes the final steam stripper, which is an energy intensive step.5 Moreover, the final steam stripper produces the most hazardous wastes. These wastes consist of nonvolatile by-products, metals and residues from catalysts, which are all burned in order to eliminate the wastes and produce steam to heat the oxidation process.3 Waste is generated during the oxidation and the separation step of this reaction, which must …show more content…
The CHHP can be produced in high yield and can then be converted to KA oil in a high yield. CHHP is converted to KA oil by decomposing the CHHP with homogeneous or heterogenous catalysts containing Co, Cr, Mo, V, Cu, or Ru.6 Another method to convert CHHP to KA oil is by dehydrating the CHHP with caustic soda or by dehydrogenating it. Using caustic soda in the dehydration produces more ketone products in the KA oil, while dehydrogenating the CHHP produces more alcohol products in the KA oil.3 In order to get a high yield (as high as 75%) of CHHP, companies use methods including: eliminating metal catalysts in the oxidation step, minimizing cyclohexane conversion, passivating reactor walls, lowering the reaction temperature, adding water to the reaction mix to extract acid catalysts from the cyclohexane phase, and adding metal-chelating agents to the reaction