Zepeng Zhao,Wenguang Zhou,Guozhang Chang,Lungang Chen,Chenguang Wang,Yuhe Liao,Jinxing Long,Longlong Ma,Yong Liu
In this study, the structure–activity relationships were investigated in converting biomass-derived furfural into cyclopentanone (CPO) or tetrahydrofuran alcohol (THFA) using a rinsing method to modulate the NiCoAl catalyst. Characterization of two catalysts, NiCoAl (without rinsing) and NiCoAl-R (with rinsing), reveals differences in morphology, composition, and acidity. Rinsing induced a transition from agglomerate to layered structure in NiCoAl-R, which exhibited higher acid strength and improved Lewis to Brønsted acid ratio. NiCoAl-R contained a high percentage of metal oxides, while NiCoAl had a high percentage of metallic species on its surface. These distinctions resulted in varied performance in FFA hydrogenolysis, with NiCoAl-R favoring CPO formation and NiCoAl facilitating THFA production. In situ DRIFTS experiments reveals differing furfural sorption states, and DFT calculations highlighted the higher activity of metal oxides in ring-opening reactions. This investigation elucidates the intricate relationship between catalyst properties and performance, offering insights for tailored catalyst design in biomass conversion.
The hydrodeoxygenation of lignin-derived phenolic compounds holds great promise for biomass-derived liquid fuel production. However, achieving a consistently high cyclohexane yield poses a formidable challenge. In this study, NiCoAl catalysts were successfully synthesized using the solution combustion method for the hydrodeoxygenation of lignin-oil. The impact of calcination temperature on the preparation of NiCoAl catalysts was investigated. The results indicate that the selectivity of cyclohexane exhibits an initial increase followed by a decrease as the calcination temperature rises. Notably, the NiCoAl-600 catalyst reached 99.99% guaiacol conversion, with the highest selectivity of cyclohexane (97.96%) achieved. Characterization results demonstrate that the transition of the spinel structure from normal to inverse with rising calcination temperature. Moreover, the catalyst particle size initially decreases and then increases, while the oxygen vacancy concentration in the catalyst increases. It was found that these properties contribute to a better hydrodeoxygenation performances of guaiacol and other phenolic compounds over non-noble NiCoAl catalyst. Possible reaction pathway and mechanism are proposed and discussed. Additionally, the spinel-structured NiCoAl-600 catalyst has good thermal stability, ensuring potential application in the upgrading of lignin-oil.
Reduction of high oxidation level furancarboxylic acid (FA) with the retention of the carboxyl group is particularly important for the utilization, however, it has been rarely explored over non-precious catalysts and is challenging. Here, we demonstrate an excellent noble-metal-free trimetallic NiCoAl catalyst for the reductive esterification of FA to methyl 2-tetrahydrofuroate (MeTHFC), which delivers the complete conversion of FA and MeTHFC yield of up to 99%. More importantly, Ni 0.5 Co 0.5 Al could offer Y MeTHFC > 90% over five reusability cycles. Detailed investigations suggest that the high activity originates from the synergistic of Ni-Co alloys sites and acid sites in Ni 0.5 Co 0.5 Al. The Ni-Co alloy sites were mainly responsible for the adsorption and dissociation of H 2 , which in turn improved hydrogenation activity, while the acid sites facilitated the esterification of FA and the adsorption and further activation of the furan ring. This work provides an eco-friendly noble-metal-free catalyst to enrich the strategies for the reductive esterification process.
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