Direct SVUV-PIMS identification of unstable oxygenated intermediates in ethanol to butadiene reaction

Abstract

Unstable oxygenated intermediates widely exist in biomass catalytic reaction but difficult to experimentally observed. Synchrotron-based vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) was employed for identification of the unstable oxygenate intermediates...

A study of the conversion of ethanol to 1,3-butadiene: effects of chemical and structural heterogeneity on the activity of MgO–SiO2 mixed oxide catalysts

“…It is argued that these species are formed either via direct surface reaction between AL and ethanol, 11,90 or by Meerwein-Ponndorf-Verley (MPV) reduction of CAD, which is obtained from AL by aldol addition and condensation. 13,55,91,92 Recently, Yang et al 28 successfully identified the aldol addition product 3-hydroxybutanal (i. e., acetaldol), the intermediate of CAD, but not under commonly used reaction conditions. We never detected acetaldol and never found CAD in the product mixture in concentration that could be considered as strong enough evidence for the role of CAD or CAD-like surface species as an intermediate of the ETB reaction.…”

“…1 The potential of heterogeneous catalytic ETB process has even been demonstrated at industrial level. 2 The most commonly used supports/catalysts for the reaction are mixed oxides, such as MgO-SiO 2 3,4,[13][14][15][16][17][18][19][20][21][22]5,[23][24][25][26][27][28][29][6][7][8][9][10][11][12] or ZrO 2 -SiO 2 [30][31][32][33][34] , and their derivatives, obtained through modification by metals, such as, Ag 4,27,31,35,36 , Cu 16,27,33 , and Au 10 , or by metal oxides ZrO 2 9,36,37 , ZnO 9,16,19,23,…”

“…The most commonly used supports/catalysts for the reaction are mixed oxides, such as MgO–SiO 2 3–29 or ZrO 2 –SiO 2 , 30–34 and their derivatives, obtained through modification by metals, such as Ag, 4,27,31,35,36 Cu, 16,27,33 and Au, 10 or by metal oxides ZrO 2 , 9,36,37 ZnO, 9,16,19,23,32,37 In 2 O 3 , 23 and Ga 2 O 3 . 23,38 Previous studies have shown that neat mixed oxides have significant catalytic activity in the ETB reaction and that additives can increase the activity by promoting ethanol dehydrogenation and C–C coupling reactions.…”