Optimization separation of paraxylene & n-butyl acetate in heterogenous azeotropic distillation column (simulation) / Muhamad Nor Firdaus B Zainal Abiddin

Faculty of Chemical and Process Engineering Technology

Final Year Report (Bachelor of Chemical Engineering ) -- Universiti Malaysia Pahang Al-Sultan Abdullah - 2024

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Traditionally, acetic acid is separated from water using binary distillation. To optimize energy consumption, heterogenous azeotropic distillation is introduced where N-butyl Acetate (NBA) is injected into the system to create an azeotropic condition with water thus reducing the water-NBA azeotrope boiling point to 90oC. In the process of manufacturing terephthalic acid, very small amounts of unreacted p-xylene (PX) may enter into the feed stream of an acetic acid dehydration column which can reduce this separation efficiency. Based on the problem, it is proposed to purge PX in the system to prevent accumulation >15wt% in the system by using a redundant distillation column. This thesis will study the possibilities to separate PX – NBA using distillation column in the presence of water in the system. A small amount of the organic reflux will be purged to the other column where NBA (top product) will be recycled back in the system and PX (bottom product) will be sent to waste water treatment (WWT). By using Aspen Plus software, the separation of PX-NBA will be simulated by varying the distillate to feed ratio, water concentration in the feed, and the number of stages. The objective of this study is to achieve less than 5wt% of PX at the top of the column thus reducing the PX accumulation in the system to less than 15wt%. From literature, PX accumulation must be controlled below 15% to ensure heterogenous azeotropic distillation (HAD) operates at its maximum efficiency (Wang & Huang, 2012) .