Insights on Guerbet Reaction: Production of Biobutanol From Bioethanol Over a Mg–Al Spinel Catalyst

Abstract

The production of biobutanol from bioethanol by the Guerbet reaction is an alternative pathway to renewable sources. The commercial viability of this green route requires improvements in the process development. This study experimentally examines the influence of operating conditions on the performance of a Mg–Al spinel catalyst prepared from hydrotalcite precursors. This catalyst demonstrates an exceptional performance in the Guerbet reaction with a promising activity/butanol selectivity balance, excellent long-term stability, and very-low-carbon footprint (CO2 generation as by-products is minimal). This study showcases a systematic strategy to optimize the reaction parameters in the Guerbet reaction for biobutanol production using an advanced spinel catalyst. Upon carefully adjusting temperature, pressure, space velocity, and reactants co-feeding, very promising conversion (35%) and butanol selectivity values (48%) were obtained.

Utilizing Undissolved Portion (UNP) of Cement Kiln Dust as a Versatile Multicomponent Catalyst for Bioethylene Production from Bioethanol: An Innovative Approach to Address the Energy Crisis

“…This finding can be attributed to the fact that a higher space velocity corresponds to a higher flow rate per mass of the catalyst, which reduces the contact time between the reactants and the catalyst. As a result, an increase in space velocity led to a decrease in ethanol conversion. ,, …”

“…As a result, an increase in space velocity led to a decrease in ethanol conversion. 22,63,64 The product selectivity during bioethanol dehydration is strongly influenced by WHSV. The same trend of %conversion of bioethanol was observed in the selectivity toward ethylene as the main product.…”

H2 Pressure Dependence in the Homogeneously Catalyzed Guerbet Reaction of Ethanol to Butanol using Mn(I) and Ru(II)

“…[33] The combination of different metals for the tailoring of catalyst properties through the combination of different reactivity modes has previously been exploited in heterogeneously catalyzed Guerbet reactions. [27][28][29][38][39][40] Exemplarily, the mixed metallic copper oxide/hydroxy apatite system to allow a navigation of the H 2 -dependence of the Guerbet network. [38] Based on these ideas, the effect of combining 1 : 1 mixtures of the Mn and Ru-based complexes 5-RuÀ R 2 (R=Ph, i Pr), 2-RuÀ Cy 2 and 5-MnÀ R 2 (R=Ph, i Pr) containing the same respective ligands was studied, (Figure 6).…”

“…Heterogeneous catalyst systems often lack selectivity, favor additional side-reactions such as ether formation and intrinsically do not perform well for multi-step condensation reactions due to the low concentration of the mostly gaseous reactants. [1][2][3][21][22][23][24][25][26][27][28][29] Homogeneous catalysts, particularly Ru(II) and diagonally related Mn(I) complexes with P,N donor ligands, are promising but achieving high space-time yields combined with butanol-selective catalysts and an efficient base use remains challenging. [1,2,[4][5][6][7][8][9][10][11][30][31][32] Current approaches involving relatively low baseloads in the range of 5-10 mol% are compiled in Table S2 within Section S2 contained in the Supporting Information and the respective (preÀ )catalysts are shown in Figure 1.…”

“…A part of the network of reactions is shown in Scheme 1. Heterogeneous catalyst systems often lack selectivity, favor additional side‐reactions such as ether formation and intrinsically do not perform well for multi‐step condensation reactions due to the low concentration of the mostly gaseous reactants [1–3,21–29] . Homogeneous catalysts, particularly Ru(II) and diagonally related Mn(I) complexes with P , N donor ligands, are promising but achieving high space‐time yields combined with butanol‐selective catalysts and an efficient base use remains challenging [1,2,4–11,30–32] …”