Hydrogen generation by photocatalytic reforming of potential biofuels: Polyols, cyclic alcohols, and saccharides

Abstract

A B S T R A C TWe have studied hydrogen gas production using photocatalysis from C2-C5 carbon chain polyols, cyclic alcohols and mono and di-saccharides using palladium nanoparticles supported on a TiO 2 catalyst. For many of the polyols the hydrogen evolution rate is found to be dictated by the number of hydroxyl groups and available a-hydrogens in the structure. However the rule only applies to polyols and cyclic alcohols, while the sugar activity is limited by the bulky structure of those molecules. There was also evidence of ring opening in photocatalytic reforming of cyclic alcohols that involved dehydrogenation and decarbonylation of a CÀ ÀC bond.

Pd local structure and size correlations to the activity of Pd/TiO2 for photocatalytic reforming of methanol

“…The increased activity of 0.6% Pd/TiO 2 catalysts produced at 1 1C was compared with our previous finding in which the rate of hydrogen production showed a twofold enhancement in comparison with Pd/TiO 2 produced via an impregnation method. 10,20 As the impact of controlling the size of metal nanoparticles on increasing H 2 productivity is dramatic, we therefore increased the Pd metal loading to study its effect on photocatalytic performance. The Pd loadings were varied at 0.6 wt%, 1 wt%, 2 wt% and 4 wt%.…”

“…We have previously investigated the activity of Pd/TiO 2 for photocatalytic reforming of alcohols with the mechanism of hydrogen production involving dehydrogenation of alcohol on the Pd surface and water reduction occurring at the Pd-TiO 2 interface. [20][21][22][23] The efficiency of Pd to promote electron transfer from the conduction band of the semiconductor is not limited to TiO 2 , and studies on visible light driven photocatalysts such as BiFeO 4 and GaN-ZnO showed enhancement in the photocatalytic performance for hydrogen production. [24][25][26] Alteration of the Pd morphology to nanocubes improved the hydrogen production from Pd/2D-C 3 N 4 composites due to the efficient separation of photogenerated energy carriers.…”

The Role of Surface Texture on the Photocatalytic H2 Production on TiO2

“…This rule is not followed by the cyclic alcohols and especially sugar (glucose, fructose and sucrose). For the reforming of cyclic alcohols it was also observed the dehydrogenation and decarbonylation of α CC bond [107].…”

“…Numerous are the cocatalysts coupled with TiO 2 proposed to maximize the rate of electron transfer to H + and consequently increase the overall efficiency of both water photosplitting and photoreforming. The most efficient cocatalysts are noble metals such as Pt, Au and Pd [99][100][101][102][103][104][105][106][107][108], but also materials based on Ag, Rh, Ni, Mn, Ru, Cr, and Co were proposed [109][110][111][112][113][114][115]. Furthermore, different carbon-based materials (e.g., graphene, graphene oxide, single-wall and multi-wall carbon nanotubes, carbon nanocones, graphitic-C 3 N 4 .…”

Recent Advances in the Catalytic Production of Platform Chemicals from Holocellulosic Biomass

“…Polyols can also be synthesized from vegetable oils via epoxidation, transesterification, hydroformylation, ozonolysis and thiol‐ene addition. Kennedy et al . recently published a model predicting H 2 production from polyols employing Pd nanoparticles on TiO 2 at 0.5 % weight.…”