Production of bio-hydrogen by liquid processing of xylitol on Pt/Al2O3 catalysts: Effect of the metal loading

- The H2 productivity from xylitol conversion on Pt/Al2O3 increases with Pt loading.
- The highest H2 productivity (28 mmol H2/h gcat) was achieved on Pt(2.77%)/Al2O3.
- The gaseous/liquid products ratio depends on the surface Pt concentration.
- At a given WHSV, the H2 yield increases with surface Pt concentration.

The aqueous-phase reforming of xylitol to produce bio-hydrogen was studied on Pt/Al2O3 catalysts containing 0.30, 0.57, 1.50 and 2.77%wt Pt by varying the weight hourly space velocity (WHSV) between 0.6 and 2.4 h−1. At a constant WHSV value, the gaseous/liquid products ratio depended on the amount of surface Pt concentration on the sample (Pts). The xylitol conversion to gaseous products increased with Pts while xylitol conversion to liquid products did not change significantly. At a constant xylitol conversion, the H2 selectivity increased with Pts. The H2 yield increased continuously with both contact time and Pts. The H2 productivity (Pr, mmol H2/h gcat) increased with both WHSV and Pts; indeed, the maximum Pr value obtained when using 1% xylitol in the feed (28 mmol H2/gcat h) was obtained on Pt(2.77)/Al2O3 catalysts at WHSV = 2.4 h−1. The effect of the xylitol concentration on H2 productivity was also investigated. At a constant space velocity, the H2 selectivity and productivity decreased with increasing xylitol concentration in the feed.

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