Studies On Tne Wastes Recycling In Tne Adipic Acid Production Process

There are many wastes in the adipic acid production process, such as nitrous oxide(N2O) and X oil. However, N2O is always treated with catalytic decomposition and X oil is burned as fuels or regarded as flotation agent for coals. These methods waste large amount of recycling resources although they slove the problem of environment pollution.On one hand, we treated N2O as an oxidant for non-catalytic liquid phase oxidation of cyclohexene to cyclohexanone. We further studied the influence of reaction temperature, reaction time, nitrous oxide initial pressure on cyclohexene conversation and cyclohexanone selectivity. Research shows the cyclohexanone selectivity is high with the maximum value over95%. However, the reaction rate is very slow with only20%cyclohexene conversation after12h under250℃. Futher study on reaction mechanism and catalysts shows the reaction follows a non-free radical mechanism and normal transition-metal catalyst had no catalysis on it.On the other hand, in this paper, we searched the recycling methods of X oil systemically. The main thought was depolymerizing the cyclohexanone polymer and then recycling the organic components of low molecular with high added value. Then, we explored many methods, such as liquid phase air oxidation, nitric acid oxidation, hydrolysis, alcoholysis. water vapor degradation and hydrocracking. The main indentified product of former two methods was adipic acid and the yield of it did not exceed10%; The main indentified products of the other four methods were cyclohexene, cyclohexanol and cyclohexanone with the maximum yield22%for hydrolysis,19.5%for alcoholysis,15%for vopor degradation and dydrocracking. On the basis of the above, we investigated the effect of catalysts like sodium hydrate, concentrated sulfuric acid, dodecyl benzenesulfonic acid on X oil hydrolysis reaction. We found that the main products generated from the hydrolysis of the two dimeric polymer in majority. Acidic catalysts with sulfo group show better catalytic effect as compared to basic catalysts. The maximum yield of X oil hydrolysis reaction using dodecyl benzenesulfonic acid can reach22%, with the concentrated sulfuric acid reaching19%and the sodium hydrate17.5%.