# Energy and Capital Cost Reduction in Ester Transesterification Using an Optimized Reactive Distillation System with Prefractionation

## TL;DR

This paper introduces an optimized reactive distillation system with prefractionation to efficiently recover valuable products from industrial waste streams while reducing energy and costs.

## Contribution

The novel RDPFC system achieves significant energy and cost savings in ester transesterification processes.

## Key findings

- The RDPFC system achieves 99.2 mol% MeAc conversion and high-purity MeOH and BuAc.
- The system reduces energy consumption by 67% compared to traditional methods.
- The removal of the entrainer and recovery unit contributes to the energy savings.

## Abstract

Reactive distillation is a highly efficient process,
but its application
presents significant challenges in mixtures that have azeotropes,
such as in the transesterification of methyl acetate (MeAc) and methanol
(MeOH) with n-butanol (BuOH). This paper proposes
a reactive distillation with a prefractionation column (RDPFC) system
to valorize the waste stream from the poly­(vinyl alcohol) industry
(30.7 wt % MeAc and 69.3 wt % MeOH) to recover high-purity MeOH and
valuable n-butyl acetate (BuAc). The process was
modeled and optimized in Aspen Plus version 12.1, with the objective
of minimizing the total annual cost (TAC). The proposed system incorporates
a prefractionation column (PFC) consisting of 26 stages working under
vacuum conditions (0.6 atm) alongside a reactive column (RC) with
38 stages operating at high pressures (8 atm) to improve the conversion
of the reaction. The RDPFC process attains a MeAc conversion rate
of 99.2 mol %, yielding products that align with commercial specifications,
including over 99.85 wt % MeOH and more than 99.5 wt % BuAc. A comparative
analysis reveals that the RDPFC configuration utilizes 2.56 GJ/tBuAc,
showcasing a significant 67% reduction in energy consumption when
compared to the traditional reactive and extractive distillation (RED)
process. The removal of the entrainer and its corresponding recovery
unit primarily accounts for this improvement. This study suggests
that the RDPFC system could be a highly efficient and economically
attractive solution for valuing waste streams in the poly­(vinyl alcohol)
industry.