Butadiene Formation from Ethanol over Silica-Magnesia Catalysts

Abstract

Butadiene formation reaction from ethanol over various kinds of silica-magnesia having different MgO contents were studied from the standpoint of its acid-base catalysis. Maximum acidity was obtained at 50% MgO, while basicity increased with the MgO content. Silica-magnesia (85% MgO) having adequate acidity and basicity gave the maximum activity. The reaction mechanism and the roles of acidic and basic sites are discussed. The rate controlling step is the acetaldehyde formation catalyzed by basic sites.

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO2 Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

“…The decrease in the ethanol dehydration along with the increase in the ethanol dehydrogenation as the Mg:Si molar ratio was increased is in agreement with a reduction in the catalyst acidity, as expected when the Mg:Si increases. [10,18] On the other hand, interestingly, the effect of the Mg:Si molar ratio on 1,3-BD selectivity was different between MgO-SiO2 systems and MgO-SiO2 systems containing ZrO2 and ZnO. While a smooth rise in 1,3-BD selectivity was verified as the Mg:Si molar ratio increased for pure MgOSiO2 samples, Figure 1 (a), the same trend was not observed for catalysts containing ZrO 2 and ZnO, Figure 1 We have previously studied the effect of the Mg:Si molar ratio for Zn(II) and Zr(IV) containing MgO-SiO 2 systems, using the wet-kneading method in the MgO-SiO 2 preparation.…”

“…[9] The route most widely accepted to account for 1,3-BD production from ethanol involves five consecutive reactions. [10][11][12][13][14][15][16] Initially, ethanol is dehydrogenated to acetaldehyde. Then, 3-hydroxybutanal is formed from acetaldehyde self-aldolisation.…”

“…[18,22,23,31] Due to this, it has been reported different optimum Mg-to-Si molar ratios for 1,3-BD formation, depending on the synthesis procedure employed. [13,18,23] Among the catalyst preparation procedures, different methods have been investigated such as physical mixtures of MgO and SiO2, [11,13] wet-kneading, [10][11][12][13]22,23] sol-gel, [18,24] impregnation [13] and co-precipitation. [22,25,26] Whereas it has been proven that a physical mixture between precursor oxides is not suitable for 1,3-BD formation, since resultant catalysts show similar features to single MgO and SiO2 phases, wet-kneading methods have been the most widely discussed in the literature with less attention being dedicated to sol-gel and co-precipitation methods.…”

Future Prospect of the Production of 1,3-Butadiene from Butanediols

“…Synthesis of BD from ethanol. 5,15,23,30,31,47 acetaldol should be the possible intermediates related to the formation of BD. 23,24 In addition, acetaldehyde can be used as a reactant instead of ethanol.…”

Heterogeneous catalytic Wacker oxidation of ethylene over oxide-supported Pd/VOx catalysts: the support effect

“…Several studies revealed [6,7] that higher yield of BD was obtained from a feed of AL/EL mixture than from pure EL. Therefore, there is an obvious interest to get AL from the readily available EE.…”