The photooxidation of methyl tertiary butyl ether

Abstract

AbstractMethyl tertiary butyl ether (MTBE) has been proposed and is being used as an additive to increase the octane of gasoline without the use of tetraethyl lead and alkylbenzenes. The present experiments have been performed to examine the kinetics and mechanisms of the atmospheric removal of MTBE. The kinetics of the reaction of OH with MTBE was examined by using a relative rate technique in which photolysis of methyl nitrite was used as the source of OH. With n‐butane as the reference compound a value of (2.99 ± 0.12) × 10−12 cm3 molecule−1 s−1 at a temperature of 298 K was obtained for the rate constant. The products (and product yields) for the OH reaction with MTBE in the presence of NOx were also determined and found to be t‐butyl formate (0.68 ± 0.05), methyl acetate (0.14 ± 0.02), acetone (0.026 ± 0.003), t‐butanol (0.062 ± 0.009), and formaldehyde (0.48 ± 0.05) in mols/mol MTBE converted. The OH rate constant for the major product formed, t‐butyl formate was also measured and found to be (7.37 ± 0.05) × 10−13 cm3 molecule−1 s−1. Mechanisms to rationalize the formation of the products are presented.