With the increasing demand for net-zero sustainable aviation fuels (SAF), new conversion technologies are needed to process waste feedstocks and meet carbon reduction and cost targets. Wet waste is a low-cost, prevalent feedstock with the energy potential to displace over 20% of US jet fuel consumption; however, its complexity and high moisture typically relegates its use to methane production from anaerobic digestion. To overcome this, methanogenesis can be arrested during fermentation to instead produce C2 to C8 volatile fatty acids (VFA) for catalytic upgrading to SAF. Here, we evaluate the catalytic conversion of food waste–derived VFAs to produce n-paraffin SAF for near-term use as a 10 vol% blend for ASTM “Fast Track” qualification and produce a highly branched, isoparaffin VFA-SAF to increase the renewable blend limit. VFA ketonization models assessed the carbon chain length distributions suitable for each VFA-SAF conversion pathway, and food waste–derived VFA ketonization was demonstrated for >100 h of time on stream at approximately theoretical yield. Fuel property blending models and experimental testing determined normal paraffin VFA-SAF meets 10 vol% fuel specifications for “Fast Track.” Synergistic blending with isoparaffin VFA-SAF increased the blend limit to 70 vol% by addressing flashpoint and viscosity constraints, with sooting 34% lower than fossil jet. Techno-economic analysis evaluated the major catalytic process cost-drivers, determining the minimum fuel selling price as a function of VFA production costs. Life cycle analysis determined that if food waste is diverted from landfills to avoid methane emissions, VFA-SAF could enable up to 165% reduction in greenhouse gas emissions relative to fossil jet.

No abstract

The steam reforming of coke oven gas (COG) for hydrogen production was investigated over the NiO/ MgO solid solution catalysts reduced at high temperatures. It was found that the NiO/MgO catalyst possessed good catalytic activity, and the conversions of CH 4 and CO 2 were greatly affected by the reaction temperature and steam/carbon (S/C) mole ratio. During the tested period of 100 h under a low S/C ratio of 1.0 at 875 °C, the conversions of CH 4 and CO 2 kept constant values around 97.6 and 44.3%, respectively, and the hydrogen volume content was enhanced from 58.2% in the original COG to 77.7% by 1.5 times. The catalyst characterization results of X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetry (TG) after the reaction showed that the Ni nanoparticle sizes had a slight increase and the amount of the coke deposition was ca. 1%. These results showed that the NiO/MgO catalyst was efficient and stable for the steam reforming of COG to amplify hydrogen in COG. This research will be of importance in hydrogen production from COG.

No abstract

No abstract