Mechanism of Electrocatalytic H2 Evolution, Carbonyl Hydrogenation, and Carbon-Carbon Coupling on Cu.

Aqueous-phase electrocatalytic hydrogenation of benzaldehyde on Cu leads not only to benzyl alcohol (the carbonyl hydrogenation product), but Cu also catalyzes carbon-carbon coupling to hydrobenzoin. In the absence of an organic substrate, H2 evolution proceeds via the Volmer-Tafel mechanism on Cu/C, with the Tafel step being rate-determining. In the presence of benzaldehyde, the catalyst surface is primarily covered with the organic substrate, while H* coverage is low. Mechanistically, the first H addition to the carbonyl O of an adsorbed benzaldehyde molecule leads to a surface-bound hydroxy intermediate. The hydroxy intermediate then undergoes a second and rate-determining H addition to its α-C to form benzyl alcohol. The H additions occur predominantly via the proton-coupled electron transfer mechanism. In a parallel reaction, the radical α-C of the hydroxy intermediate attacks the electrophilic carbonyl C of a physisorbed benzaldehyde molecule to form the C-C bond, which is rate-determining. The C-C coupling is accompanied by the protonation of the formed alkoxy radical intermediate, coupled with electron transfer from the surface of Cu, to form hydrobenzoin.

Conversion of waste biomass and waste nitrile gloves into renewable fuel.

The present study deals co-pyrolysis of neem seeds (NM) and waste nitrile gloves (WNG) in a semi-batch reactor with and without catalysts. Results confirmed that the yield of pyrolytic liquid was higher (43.52 wt% at NM: WNG ratio of 3:1) during thermal co-pyrolysis compared to that of catalytic co-pyrolysis (40.42 wt% and 37.14 wt% respectively with CaO and Al2O3 as catalysts). The use of catalysts increased the carbon content, acidity, and heating value and reduced the oxygen content, viscosity, and density of the pyrolytic oil. FTIR analysis suggested the presence of useful functional groups while 1H NMR analysis confirmed high amounts of paraffin and aromatic compounds in the pyrolytic oil. GC-MS analysis of pyrolytic oil confirmed that blending of NM + WNG and use of catalysts reduced the oxygenated compounds and increased the alcohol and aldehyde thereby enhancing the fuel properties.