ABSTRACT This research aims to design a Methyl Tert-Butyl Ether (MTBE) plant using the Phillips STAR process with the main tool design for the Esterification reactor (R- 101). MTBE is used as a fuel additive to increase octane number, reduce pollutant emissions, and improve engine performance. The factory is planned to be located in Bukit Batu District, Bengkalis Regency, Riau, under the name …