Reactions of cyclohexanone in contact with activated charcoal
Cyclohexanone is regarded as an important raw material to produce many useful chemicals such as hexanedioic acid, hexamethylenediamine, and caprolactam. However, it’s production usually leads to high energy consumption. Traditional technologies include three routes: oxidation of cyclohexane, hydrogenation of phenol and direct hydration of cyclohexene. Avoiding the risk of explosion and a low price of raw material, the direct hydration of cyclohexene route is selected in this paper. To enhance the energy efficiency, a novel heat-pump-assisted reactive distillation process (HPRD) is proposed and simulated through AspenPlus. The discharge compressor pressure is optimized to be 3.2 bar to minimize the cost. For purposes of comparison, two conventional processes, aqueous-phase-refluxed reactive distillation with a stripper (ARDS) and organic-phase-refluxed reactive distillation with a stripper (ORDS), are also simulated and optimized through sensitivity analysis. All these three processes are evaluated through energy and economic analysis. The results show that the ORDS process saves the total energy and annualized cost by 15% and 12%, respectively, compared with the ARDS process, while the heat-pump-assisted process realizes a significant energy saving of 65% and achieves 33% reduction in total annualized cost, demonstrating a high economic feasibility.
The products from the conversion of cyclohexanone over activated charcoal in a stream of H2 and N2 at 200–500° are cyclohexene, cyclohexanone, cyclohexane, benzene, phenol, and biphenyl. The equations of the multiplet theory were used for calculating the energy barriers of the corresponding reactions and their theoretical sequence was found. It was shown that it is necessary to consider the bond strain in the multiplet complex for the case of a charcoal catalyst. Thermodynamic calculations were made for the equilibria of a series of reactions in the first and zero approximations. It was established that cyclohexanone undergoes dismutation on pure charcoal, beginning at 200°. The experimental results are in agreement with the sequence of cyclohexanone conversions calculated from the multiplet theory with allowance for thermodynamic limitations.
By using cyclohexanone as feedstock and potassium permanganate and heteropoly acid as feedstock, adipic acid can be obtained with the aid of ultrasonic wave. The quality of adipic acid is significantly improved. The effects of the reaction conditions on oxidation of cyclohexanone to adipic are mainly discussed. The experimental results indicate that the best ratio of feedstock and catalyst, the reaction temperature, and the reaction time are 1:3, 75°C, and 40 min, respectively. The yield of adipic acid reaches a maximum value of 85%. At the same time, the effects of the different ligands are checked. The experimental results show that sulfo-salicylic acid is one of the best ligands.
Arabic
Français
Español
Português
Deutsch
Türkçe
Dutch
Italiano
Russian
Romaian