Gas-Phase Oxidation of a Propane–Propylene Mixture by Nitrous Oxide

Abstract

The present study focuses on a new method for obtaining C2−C3 carbonyl compounds (ketones and aldehydes) by the gas-phase selective oxidation of a propane−propylene mixture using nitrous oxide (N 2 O). The oxidation is carried out without catalyst in the temperature range of 623−773 K at elevated pressure. The obtained results reveal that only propylene in the propane− propylene mixture reacts with nitrous oxide. The reaction proceeds by the nonradical mechanism involving the 1,3-dipolar cycloaddition of N 2 O to the CC double bond of olefin. The main reaction products are acetone, propanal, and acetaldehyde. At 723 K and a pressure of 0.7 MPa, the total selectivity to these products amounts to 74.6%, the N 2 O conversion attains 74.5%, and the propylene conversion is 12.5%. An important feature of the reaction is the additional formation of methylcyclopropane with a selectivity of ca. 6%.

Gas-Phase Selective Oxidation of Butenes in the C4 Fraction by Nitrous Oxide

“…It is seen that C2−C4 aldehydes and ketones are the main productss of the oxidation. According to the numerous literature data, 19,[34][35][36][37][38][39][40][41][42]46,47,56 under the reaction conditions used, these products can be formed only in the reaction of N 2 O with olefins (i.e., butenes in the BBF in our case).…”

“…The gas-phase oxidation with N 2 O of the BBF, which contains all butene isomers, actually results in obtaining the carbonyl compounds listed above (Table 1). Since N 2 O interacts exclusively with the olefinic CC bonds, while remaining inert to alkanes and other non-olefinic compounds, 19,[34][35][36][37][38][39][40][41][42]46,47,56 the aldehydes and ketones do not enter secondary oxidation. In addition, similar to other olefins, 19,[34][35][36][37][38][39][40][41][42]46,47,56 the reaction of butenes with N 2 O does not lead to deep oxidation products (H 2 O, CO, and CO 2 ).…”

“…The gas-phase noncatalytic oxidation of BBF by N 2 O was studied in a flow setup using on-line chromatographic analysis of the gas phase. 42 A stainless-steel tubular reactor (volume 25 mL, inner diameter 4 mm) was fed with a BBF/N 2 O gas mixture containing 10−30 mol % N 2 O. The N 2 O was supplied by a mass flow controller (MKS Instruments).…”

“…For example, propylene in the propylene−propane mixture can be selectively oxidized with N 2 O to aldehydes and ketones in the gas phase. 42 Therefore, it is interesting to test the possibility of producing MEK via the direct oxidation with N 2 O of refinery streams containing butenes. In particular, the C4 fractions from catalytic cracking, which contain mainly butenes and butanes, could potentially be used as a suitable feedstock for such oxidation.…”

Theoretical Study on the Gas‐Phase Oxidation Mechanism of Ethylene by Nitrous Oxide

“…The decomposition of oxadiazole intermediate with the release of N 2 led to ketone or aldehyde. Olefin structure determines the composition of the resulting products [37,38], the main oxidation products are ketones for 1,2-disubstituted internal olefins, while 1-olefins major get the mixtures of ketones, aldehydes, and cyclopropane derivatives [39,40].…”