Coupling Natural Halloysite Nanotubes and Bimetallic Pt–Au Alloy Nanoparticles for Highly Efficient and Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid

Abstract

The aerobic oxidation of 5-hydroxymethylfurfural (HMF), a key platform compound derived from biomass, to 2,5-furandicarboxylic acid (FDCA) is a highly important reaction in the production of green and sustainable chemicals. Here, we developed a highly efficient and stable halloysite-supported Pt−Au alloy catalyst for the selective oxidation of HMF to FDCA. The catalyst was synthesized through the organosilane functionalization of halloysite nanotubes, followed by the in situ formation and dispersion of Pt−Au alloy nanoparticles on the internal and external surfaces of nanotubes. The composition, morphology, and structure of the prepared catalyst were characterized. The catalyst with the optimal composition of Pt/Au molar ratio of 1/4 and metal loading of 1.5 wt % exhibited outstanding catalytic activity for the oxidation of HMF to FDCA using O 2 as an oxidant with 100% conversion of HMF and 99% selectivity of FDCA. This excellent catalytic performance is mainly attributed to the high dispersion and alloying effects of bimetallic nanoparticles, which promoted the activation of reactants or intermediates and further improved FDCA selectivity. Furthermore, the halloysite-supported Pt/Au bimetallic catalyst showed high stability and reusability. This study provides a promising strategy by combining clay mineral halloysite and bimetallic alloys for developing efficient catalysts with high FDCA selectivity and stability for the oxidation of HMF to FDCA.

Leveraging Pt/Ce1–xLaxO2−δ To Elucidate Interfacial Oxygen Vacancy Active Sites for Aerobic Oxidation of 5-Hydroxymethylfurfural

“…In-situ DRFTIR measurements were then performed over the catalysts of Pt/3D-Ce 0.9 La 0.1 O 2−δ and Pt/3D-Ce 0.7 La 0.3 O 2−δ to investigate the adsorption and activation of reactants on interfacial oxygen vacancy sites. Taking into account the fact that the oxidation of alcohol hydroxyl groups (HMFCA → FFCA) is the rate-determining step in the aerobic oxidation of HMF toward FDCA, 65 furfuryl alcohol (FA) was selected as the model molecule for HMFCA to eliminate the influence of aldehyde groups. Figure S19a, b, respectively, show the in-situ DRFTIR spectra of Pt/3D-Ce 0.9 La 0.1 O 2−δ and Pt/3D-Ce 0.7 La 0.3 O 2−δ after FA preadsorption at 90 °C, and the assignment of absorption bands observed is given in Table S5.…”

Catalytic Conversion of 5‐Hydroxymethylfurfural to High‐Value Derivatives by Selective Activation of C−O, C=O, and C=C Bonds

“…developed a highly efficient and stable halloysite‐supported Pt−Au alloy catalyst, which was synthesized through the organo‐silane functionalization of halloysite nanotubes, followed by the in‐situ formation and dispersion of Pt−Au alloy nanoparticles on the internal and external surfaces of nanotubes (Figure 16). 1.5 wt% metal loading exhibited outstanding catalytic activity with 100 % conversion of HMF and 99 % selectivity of FDCA at 95 °C, 1.0 MPa O 2 , and 3 h, and the excellent catalytic performance is mainly attributed to the high dispersion and alloying effects of bimetallic nanoparticles [91b] . The bimetallic catalysts containing precious metal and transition metal were also applied for aerobic oxidation of HMF.…”

Ag substituted Au clusters supported on Mg-Al-hydrotalcite for highly efficient base-free aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid

“…Supports play a vital role in catalytic reactions, because they generally provide anchor sites for metal particles and acidbase property for specific reactions. 30,37 In this work, MgAl-HT supported Au NCs and Au-Ag bimetallic NCs were synthesized via a three-step method, as illustrated in Scheme 2. Briefly, Au and Au-Ag bimetallic NCs were prepared through a NaOHmediated NaBH 4 reduction method, with cysteine as the protective ligand.…”

“…32 In aerobic oxidation of HMF, Au-based bimetallic catalysts are of particular interest because of the increased efficiency and catalytic stability. [36][37][38] For example, TiO 2 -supported Au-Cu alloy catalysts displayed superior activity and remarkable stability compared to their monometallic counterparts (i.e. Au/TiO 2 and Cu/TiO 2 ).…”

“…36 Au-Pt alloy particles supported on HNT exhibited good performance owing to the high density of metal active sites. 37 Au-Ag alloy catalysts with varying Ag/Au molar ratios showed a synergistic effect between Ag and Au, and displayed varying selectivity of FDCA and catalyst stability against sintering. 38 Nevertheless, to date, supported gold NCs doped with other metal atoms have not been employed for HMF oxidation.…”