Au Nanoparticles Anchored on Sulfonated Carbon Nanotubes for Benzyl Alcohol Oxidation

Abstract

Promotion of gold (Au)−support synergy provides considerable opportunities to enhance the thermal stability of nanoscale gold catalysts. In this work, we developed an anchorage strategy for Au on sulfonated carbon nanotubes (CNTs), inspired by the mysterious Au−S synergy. S species existed mainly as sulfonyl groups with a tiny quantity of S atoms inserted in the carbon skeleton. The geometric and electronic structures of gold particles were modified, rendering them efficient for the selective oxidation of benzyl alcohol. Using integrated experimental and theoretical approaches, we explicitly show that Au particles of around 2.6 nm were highly dispersed at a S/C ratio of 1.4 at. %. Electrons were delivered from Au to the support with a maximized Au−C interfacial perimeter and promoted adsorption ability with the reactant. However, high S/C atomic ratios (≥3.9%) resulted in increased surface acidity and self-rearrangement of particles with abundant high-coordinated Au 3+ sites at the expense of conversion loss. Under appropriate sulfonation, Au/S 1 CNT exhibited a TOF value of 2294 h −1 at only 50 °C. This work disentangled the structure manipulation of Au catalyst with a suitable action mode between Au and S species to afford a better Au catalyst with resistance to coarsening.

Structural Construction of Au–Pd Nanocomposite for Alkali-Free Oxidation of Benzyl Alcohol

“…Bimetallic nanoparticles were well dispersed on the CNT outside surface with average size of 6.9 nm, which is slightly larger than those in the Au 1 Pd 1 /CNT and Au 1.5 Pd 1 /CNT. Metal particles were partially encapsulated by carbon support, suggesting the strong interaction between the particles and support. − The HAADF-STEM EDX elemental line scan of an isolated particle (Figure S9e, f) suggested the coexistence of Au and Pd elements in such bimetallic or alloy particle. The elemental analysis (Figure S10) confirmed the atomic ratio of Au/Pd as 3.6.…”

Promotion of Au nanoparticles on carbon frameworks for alkali-free aerobic oxidation of benzyl alcohol

“…In a previous study, we used carbon-supported gold nanoparticles in a colloid immobilization method (Luo et al, 2022a;Luo et al, 2022b). Our results showed that the surface of carbon materials could be easily tuned by introducing hetero-atoms, which provided rapid reaction rates and stability under appropriately designed surfaces and structures.…”

Rhenium in Heterogeneous Catalysis: A Rising Star for Hydrogenation Reactions

“…Adsorption of SO 2 or S-containing compounds even in a minor amount easily caused the strong adsorption on the surface of the metal sites, which is a fatal and leading step for the deactivation of most metal catalysts. 90 However, as mentioned above, Re catalysts were also capable of catalyzing the selective hydrogenation of S-containing reactants without clear sulfur poisoning, and the most typical ones were thiophene derivatives. Different from the weak adsorption between Re species and the aromatic ring, C−S bond cleavage in 4,6-dimethyldibenzothiophene (4,6-DMDBT) during hydrodesulfurization has been proposed to follow the aromatic ring partial hydrogenation due to the presence of steric hindrance around the S atom.…”

“…A surprising superiority of using rhenium was the sulfur- and poison-resistant ability. Adsorption of SO 2 or S-containing compounds even in a minor amount easily caused the strong adsorption on the surface of the metal sites, which is a fatal and leading step for the deactivation of most metal catalysts . However, as mentioned above, Re catalysts were also capable of catalyzing the selective hydrogenation of S-containing reactants without clear sulfur poisoning, and the most typical ones were thiophene derivatives.…”