Selective Oxidation of Cinnamyl Alcohol to Cinnamaldehyde with Air over Bi-Pt/Alumina Catalysts

Promoting role of bismuth on carbon nanotube supported platinum catalysts in aqueous phase aerobic oxidation of benzyl alcohol

“…Many early studies have proved that bismuth and lead as p-electron metals favored the oxidation of polyhydroxy carboxylic acids into their α-keto derivatives, which explained the promoting role of Bi on selectivity [11][12][13][31][32][33]. Presently, Bi was also shown to enhance selectivity in alcohol oxidation by suppressing parallel reaction on a Bi-modified AuPd/AC catalyst [34].The promoting effect of Bi on reaction rate [1,21,35] was referring to: (1) Bi formed a geometric blocking on noble metal, which decreased the size of active site ensembles and suppressed the strong adsorption of poisoning intermediates [36]. (2) OH ads adsorbed on Bi adatoms to form new active sites, such as Pt-Bi-OH ads [36].…”

“…PdBi/C was also reported in the catalytic oxidation of glucose to gluconate or gluconic acid by Besson et al [14] and Wenkin et al [15]. Since then, Bi-promoted Pt-and Pd-based catalysts have been employed in many other alcohol and aldehyde oxidation reactions, such as glyoxal [16], L-sorbose [17], 9-decen-1-ol [18], polyethylene glycol dodecyl ether [19], n-butanol [20] and so on.In addition to the aforementioned straight chain alcohols and aldehydes, Baiker and coworkers [21][22][23][24][25][26][27][28][29] had made great effort on the selective oxidation of aromatic alcohols (such as cinnamyl alcohols, 1-phenylethanol and benzyl alcohol) on alumina, carbon or polyaniline-supported Pd-Bi and Pt-Bi catalysts. Among these reactions, selective oxidation of benzyl alcohol to benzaldehyde is of importance because the product serves as the versatile intermediates in synthetic chemical industries [30].…”

“…The promoting effect of Bi on reaction rate [1,21,35] was referring to: (1) Bi formed a geometric blocking on noble metal, which decreased the size of active site ensembles and suppressed the strong adsorption of poisoning intermediates [36]. (2) OH ads adsorbed on Bi adatoms to form new active sites, such as Pt-Bi-OH ads [36].…”

Mechanistic Studies of Alcohol Selective Oxidation

“…Platinum and palladium are effective catalysts for alcohol oxidation when used alone; however, significant stability and selectivity improvements have been observed on incorporation of a second (usually less active) metal promoter such as Bi, Pb, and Sn [63][64][65]. These observations are common to aerobic selox of allylic and benzylic alcohols, as well as polyols such as propylene glycol [64] and glycerol [66].…”

Oxidation of Alcohols with Molecular Oxygen

“…In contrast, a non-aqueous medium, an apolar catalyst surface, and rapid removal of the water coproduct are favored to minimize further oxidation of aldehydes to carboxylic acids (Scheme 8). For the oxidation of water-insoluble alcohols, the choice may be organic solvents and ionic liquids [80], or alternatively a dense (''supercritical'') CO 2 [81] and a water-detergent system [82] when flammable solvents are to be avoided.…”