Unraveling the alternative process configurations for more environmentally friendly Maleic Anhydride production

초록

This study aims to propose and evaluate alternative configurations for producing maleic anhydride (MA) through the n-butane oxidation pathway to enhance overall environmental friendliness. Seven alternative configurations, which vary in the number of non-adiabatic reactors and heat exchange methods, as well as the stripping agents used for recovering MA in the purification section, are rigorously designed and comprehensively compared. Among the proposed configurations, we have found that the one utilizing single reactor with co-current cooling and water as the stripping agent ( Scheme 2 ) shows the most promise. It has an optimal yield of 70.0 %, an energy efficiency of 97.52 %, and exergy efficiency of 44.92 %. A cradle-to-gate life cycle impact assessment determines a Global Warming Potential (GWP) of 0.091 kg-CO2eq/kg-MA 2 eq/kg-MA from this scheme. In contrast, a techno-economic evaluation determines a minimum required selling price (MRSP) of 0.965 USD/kg-MA from this scheme. All these indicators are superior compared to those documented in the existing literature, suggesting a higher level of environmental friendliness. Subsequently, a suitable control strategy is proposed for the optimized Scheme 2 and evaluated by rejecting various kinds of feed disturbances ( i.e. , +/- 10 % change in feed flowrate, +/- 5 % change in molten salt flowrate, 1 % and 2 % of i-butane as feed impurity, and catalyst deactivation up to 40 %). Enhanced controllability is achieved by regulating the flowrate ratio between the flashed liquid and the n-butane (FL/NBU), which promptly indicates the reaction conversion during production. Based on the findings, we have concluded that overall environmental friendliness can be significantly enhanced with moderate modifications in the process configuration, which are easily feasible in the industry.

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