A FTIR Study of the Acidity of in situ Generated Brønsted Sites on NaY via Displacement Reactions

Unveiling the mechanisms of carboxylic acid esterification on acid zeolites for biomass-to-energy: A review of the catalytic process through experimental and computational studies

In recent years, there has been significant interest from industrial and academic areas in the esterification of carboxylic acids catalyzed by acidic zeolites, as it represents a sustainable and economically viable approach to producing a wide range of high-value-added products. However, there is a lack of comprehensive reviews that address the intricate reaction mechanisms occurring at the catalyst interface at both the experimental and atomistic levels. Therefore, in this review, we provide an overview of the esterification reaction on acidic zeolites based on experimental and theoretical studies. The combination of infrared spectroscopy with atomistic calculations and experimental strategies using modulation excitation spectroscopy techniques combined with phase-sensitive detection is presented as an approach to detecting short-lived intermediates at the interface of zeolitic frameworks under realistic reaction conditions. To achieve this goal, this review has been divided into four sections: The first is a brief introduction highlighting the distinctive features of this review. The second addresses questions about the topology and activity of different zeolitic systems, since these properties are closely correlated in the esterification process. The third section deals with the mechanisms proposed in the literature. The fourth section presents advances in IR techniques and theoretical calculations that can be applied to gain new insights into reaction mechanisms. Finally, this review concludes with a subtle approach, highlighting the main aspects and perspectives of combining experimental and theoretical techniques to elucidate different reaction mechanisms in zeolitic systems.

Unveiling the Adsorption Behavior and Redox Properties of PtNi Nanowire for Biomass-Derived Molecules Electrooxidation

Ni-based materials are auspicious electrocatalysts for 5-hydroxymethylfurfural oxidation reaction (HMFOR), including the adsorption and conversion of HMF and OH_ad on the electrocatalyst surface. However, the intrinsic HMFOR activity of Ni-based catalysts is far from satisfactory due to the weak adsorption of HMF and OH_ad species. Herein, a set of Pt_xNi_100-x bundle nanowires (NWs) were prepared for HMFOR, which enables a low onset-potential and large current density. Operando methods reveal that Pt modulates the redox property of Ni in PtNi NWs and accelerates the oxidation of Ni²⁺-OH to Ni³⁺-O species during HMFOR. Moreover, the adsorption studies demonstrate the synergetic roles of Pt and Ni in enhancing the HMFOR activity by forming Pt-O-Ni bonds. In detail, Ni atoms modulate the d band of Pt to alter the adsorption behavior of HMF. Pt atoms promote the adsorption of OH_ad on Ni sites. This work provides design principles for HMFOR electrocatalysts by modulating the adsorption behaviors of organic molecules and OH_ad.