| Maleic anhydride is one of the intermediate products with the highest forecasted increase in demand in the near future. Nowadays, it is predominantly produced by the partial selective oxidation of n-butane in fixed-bed reactor over VPO catalyst. In order to overcome inherent process problems including controlling of hot-spot in multi-tube reactor, decreasing of MA sensitivity caused by phosphorus loss, and a large amount of wastewater discharged from solvent purification, the main tasks as follows concentrate on optimization of reactor and process based on catalyst research before.(a) Effects of reaction conditions on n-butane partial oxidation are respectively investigated. And the intrinsic kinetic model has been established over an integral fixed-bed reactor at temperature range of420～440℃and a GHSV range of2600～3800h-1with the novel reaction network, which is based on the numerical simulation and MA oxidation experiment.(b) According to the establishment of one dimensional axial dispersion model for n-butane oxidation, effects of transfer factors on oxidation reaction are studied. And sensitivity analysis of the single-tube reactor is discussed based on the comparison between experimental data and simulation results.(c) Phosphorus loss over VPO catalyst is proved by the experiment of bed temperature and total phosphorus content. And the phosphorus experiments, such as reagent type, addition amount, excessive addition and water addition are investigated respectively. According to the single-tube reaction model containing phosphorus dynamics established on the basis of the changes of reaction network due to phosphorus loss, the development of bed temperature, phosphorus coverage over catalyst surface, and phosphorus gas phase concentration are studied with and without phosphorus addition.(d) In terms of process simulation by Aspen Plus referring to factory data, sensitivity analysis of separation section for n-butane oxidation is discussed. |
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