Pt catalysts in proton exchange membrane fuel cells (PEMFCs) typically use carbon blacks such as Vulcan (Vulcan is a registered trademark of the company Cabot Corporation) based on fossil sources. Thus, an important research task is using sustainable supports in PEMFCs. Hydrothermal carbonization (HTC) converts biomasses into chars, which are possible substitutes for fossil‐based carbons. Herein, a Pt catalyst derived from HTC of coconut shells is developed for catalysis of O2 reduction in acidic media. Thermal activation enlarges the specific surface area by factor of 7 to 546 m2 g−1 and generates electrical conductivity making the material suitable for catalysis. Pt particles of 1.8 ± 0.5 nm are distributed well on the activated carbon. Cyclic and CO stripping voltammetry show an electrochemical surface area (ECSA) of 69 ± 21 m2 gPt−1, almost identical to that of the commercial catalyst using Vulcan (69 ± 6 m2 gPt−1). Although ECSAs are highly comparable, the activity for O2 reduction is lower compared with the commercial catalyst. HTC‐derived carbon has a lower degree of graphitization, less functional oxygen groups on its surface, and a lower electrical conductivity than Vulcan. This suggests different Pt–support interactions.
Poultry farms with floor-standing poultry generate large amounts of poultry litter waste. The direct application of this waste as an organic fertilizer does not ensure sustainable and cost-efficient utilization of all waste fractions, and can also be linked to environmental hazards. Therefore, the development of new technologies is required for processing poultry litter into a safe product with higher added value. In this work, the characteristics of activated carbon derived from hydrochar, along with the liquid products obtained from hydrothermal carbonization (HTC) and the wet torrefaction (WT) of poultry litter, were investigated. Poultry litter (PL) was applied in a mixture with sawdust (SD) in the following ratios: 1:0 (PL/SD 1:0), 1:1 (PL/SD 1:1), 1:2 (PL/SD 1:2), and 2:1 (PL/SD 2:1). WT processing took place in an innovative fluidized bed system in a superheated steam medium with low overpressure (less than 0.07 MPa) at 300 °C and 350 °C for 30–45 min. Conventional HTC processing was performed in a water medium at 220 °C for 1–4 h. The hydrochar produced in the experiments was activated with steam for 1 h at 450–750 °C. The porosity characteristics of activated hydrochar were measured, including pore size, pore volume, and specific surface area, in view of potential industrial applications as an adsorbent. Additionally, the contents of 5-hydroxymethylfurfural (HMF), as high-value product, were determined in the liquid products obtained from HTC processing, as well as in the condensate obtained after WT processing. Specific surface areas of the activated hydrochars may still be too low for application as adsorbent material. Hence, its use as a biofertilizer and soil improver should be preferred. Interestingly, the liquid fraction obtained from the innovative WT process displayed a significantly higher 5-HMF content compared to the conventional HTC process.
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