abstracts - Институт катализа им. Г.К. Борескова

OP-II-36provide stable experimentation of analysing the reaction products. Additionally, GC and GC-MS was also used to identify various products.Results and DiscussionIn the oxidation of 1-butene more than 30 products were identified by on line MS andGC-MS including C 1 -C 5 carboxylic acids and anhydrides with AcOH as main product (70 %selectivity). Along with these products, C 1 -C 4 alcohols, C 1 -C 4 mono- and dicarbonylcompounds, C 1 -C 4 carboxylic acid and esters, butadiene, dioxolane and dioxane derivativesand products of total oxidation were identified. It was observed that the selectivity of AcOHincreased with increase in residence time and conc. of O 2 . The highest selectivity of AcOHwas found in a temperature interval from 200 to 230 °C.In the SSITKA measurements the distribution of 16 O and 18 O in the oxidation productswas determined after single or periodic switching of 16 O to 18 O. During the oxidation of 1-butene in presence of water, it was found that the isotope transfer from O 2 in AcOH was fastbut limited(Fig. 1a) The degree of isotope replacement in AcOH and in presence of H 2 O was app.10 % at 160 °C and increased to 25-35 % with increase of the reaction temperature to 260 °C.16O 2 18 O 2 T: 240°C 17 % H 2OT: 240°C dry flowMS-Intensitya60 62 64AcOH (2xO 16 ) -> AcOH (O 16 O 18 ) + AcOH (2xO 18 )MS-Intensityb16O 2 18 O 2AcOH(2xO 16 ) -> AcOH(O 16 O 18 ) + AcOH (2xO 18 )60 62640 250 500 750 1000 1250 1500time (s)0 1000 2000 3000 4000 5000 6000time (s)Fig. 1: O-isotopes exchange in acetic acid (AcOH) during the oxidation of 1-butene inpresence (17%) (a) and absence (b) of water, catalyst: VO x -TiO 2These results clearly indicated that water participated in the reaction and an O-isotopeexchange took place between oxygen and adsorbed water molecules on the catalyst surface,which limited isotope exchange during the oxidation of 1-butene in presence of H 16 2 O. Thewater was involved in reaction steps such as the formation of 2-BuOH and/or AcOH [6].Alternative mechanisms of the 18 O-isotope transfer during the oxidation of 1-butene inabsence and presence of water are developed.279