Techno-economic and environmental assessments for different scenarios of utilizing n-butane in sulfuric acid alkylation process: Direct sale and maleic anhydride production

The sulfuric acid alkylation process was one of the primary industrial processes for producing alkylate oil. The raw materials used were butane and butene, with a large amount of n-butane not reacting with the butene. Therefore, two treatment scenarios which was selling n-butane directly and further utilizing it to produce maleic anhydride were proposed. Moreover, The technical, economic, and environmental effects of the scenarios were evaluated by methods such as energy analysis, net present value evaluation, uncertainty analysis, and life cycle assessment. Based on the above calculation results, three effects were integrated into the TOPSIS-AHP model for comprehensive evaluation. The results of Scenario 2 including the energy utilization rate (48.81 %), discounted revenue (81.64 M$), and profitability probability (0.93) were significantly better than those of Scenario 1 (20.96 %, 41.93 M$, and 0.76), but Scenario 2 had more serious environmental impact. The comprehensive evaluation results showed that the calculation result of Scenario 2 (0.78) was significantly better than that of Scenario 1 (0.22), so the comprehensive benefit of Scenario 2 was better. The research results of this paper provided new ideas for the utilization of n-butane in the sulfuric acid alkylation process.