Interaction of Ethanol with MgO-SiO₂ Catalysts Studied by TPD Techniques

In Situ Spectroscopic Insights on the Molecular Structure of the MgO/SiO2 Catalytic Active Sites during Ethanol Conversion to 1,3-Butadiene

“…A comparison between IWI and WK catalysts showed that the IWI catalyst is more active in catalyzing dehydration than dehydrogenation reactions. This is further shown by the much higher 1,3-BD yield attained by the WK catalyst (73%) as compared to the IWI catalyst (45%) across the 50–500 °C temperature range . This different activity was suggested to be due to the different silicate phase formation on the catalyst surface depending on the preparation technique .…”

“…Catalysts prepared using different methods, for example, incipient wetness impregnation (IWI) and wet-kneading (WK), , resulted in a large activity difference with the IWI-prepared catalyst yielding only ∼5% conversion at 300 °C compared to the WK catalyst yielding ∼50% conversion at 425 °C. A more appropriate comparison was done by He, et al, where differently prepared catalysts were tested using pulse-temperature-programmed desorption (TPD) method . A comparison between IWI and WK catalysts showed that the IWI catalyst is more active in catalyzing dehydration than dehydrogenation reactions.…”

“…A more appropriate comparison was done by He, et al, where differently prepared catalysts were tested using pulse-temperature-programmed desorption (TPD) method. 10 A comparison between IWI and WK catalysts showed that the IWI catalyst is more active in catalyzing dehydration than dehydrogenation reactions. This is further shown by the much higher 1,3-BD yield attained by the WK catalyst (73%) as compared to the IWI catalyst (45%) across the 50−500 °C temperature range.…”

Ethanol-to-butadiene: the reaction and its catalysts

“…Wet-kneading-the process of combining two or more solid precursor materials (mechanically or magnetically) in a liquid medium 255 -is a very common method for preparing the MgO-SiO 2 catalyst in the ethanolto-butadiene reaction; with water as a solvent, it has produced the most active catalyst of its kind 267 and a majority of studies used wet-kneaded samples. 1,51,92,111,126,127,174,230,251,255,[266][267][268][269] The high butadiene yield provided by wet-kneaded MgO-SiO 2 has been attributed to the controlled mixing it provides. TEM and EDX-STEM have indicated that wet-kneaded materials exist in two bulk phases-crystalline MgO sheets and amorphous SiO 2 particles-with limited contact with one another.…”

“…Other synthesis methods include: the sol-gel technique, 97 co-precipitation, 51,157,174,191,270 incipient wetness impregnation, 5,9,172,269 dry milling 1,160 and mechanochemical mixing. 266 Co-precipitated metal oxides resulted in excessive phase mixing; more Mg-O-Si linkages were detected compared to wet-kneaded MgO-SiO 2 .…”