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.

Coatings comprised of carbon nanotubes are very black; that is, characterized by low reflectance over a broad wavelength range from the visible to far infrared. Arguably there is no other material that is comparable. This is attributable to the intrinsic properties of graphene as well as the morphology (density, thickness, disorder, tube size) of the coating. The need for black coatings is persistent for a variety of applications such as baffles and traps for space instruments. Because of the thermal properties, nanotube coatings are also well suited for thermal detectors, blackbodies and other applications where light is trapped and converted to heat. We briefly describe a history of other coatings such as nickel phosphorous, gold black and carbon-based paints and the comparable structural morphology that we associate with very black coatings. In many cases, it is a significant challenge to put the blackest coating on something useful. We describe the growth of carbon nanotube forests on substrates such as metals and silicon along with the catalyst requirements and temperature limitations. We also describe coatings derived from carbon nanotubes and applied like paint. Another significant challenge is that of building the measurement apparatus and determining the optical properties of something having negligible reflectance. There exists information in the literature for effective media approximations to model the dielectric function of vertically aligned arrays.We summarize this as well as other approaches that are useful for predicting the coating behavior along with the refractive index of graphite from the literature that is necessary for the models we know of. In our experience, the scientific questions can be overshadowed by practical matters, so we provide an appendix of our best recipes for making as-grown, sprayed or other coatings for the blackest and most robust coating for a chosen substrate and a description of reflectance measurements.

We developed a single-phase Pd/NbOPO4 catalyst for reductive etherification that displays high catalytic activity, product selectivity, and regeneration stability.

RYING solids by direct contact with the superheated vapors D of its own moisture, especially superheated steam, has t~een recommended as a highly efficient method of drying by several authors. Walker, Lewis, WcAdamns, and Gilliland (19) mention briefly the advantages of superheated steam drying.Superheated vapor has had limited application in the past. Wenzel and White (20, 21) summai,ized the past applications on drying brown coal, lignite, wood, and vegetables with superheated steam. Wenzel (20) mentioned some recent superheated st,eani installations for drying silica gel and insulating material. Super-:heated hexane vapor drying is being employed to remove hexane from extracted soybean flakes. Most recently, pilot plant equipiment is being built for drying calcium silicate with superheated st,eam. Serious consideration has rec,ently been given to drying of activated carbon, petroleum catalysts. and coal with superheated steam.Superheated vapor operation, although endowed wit'h many advantages, thermal and otherwise. has certain limitations. First, it is limited to drying solids which have an allowable temperature limit above the saturation temperature of its moisture and probably above the opemting temperature of t'he superheated vapor, depending on the degree of dryness required. Another disadvantage is that it is difficult to obtain low moist,uw contents.It was the purpose of this investigation to determine t8he evaporation rates from a liquid surface when in direct contact with its superheated vapor. Liquid surfaces were chosen sincc they present kuown surface areas xvith which accurate values of the rate of evaporation or heat transfer coefficients can be d&mninerl. The data obtained from this investigatiori is direvtly c.ompi~ral~lc to the constant rate period when drying solids.In the evaporation of liquicls with air, vapors from the liquid interface must diffuse through an air film to reach t'he mniii air -stream. The vapor in the air film is at a higher partial pressure than the vapor in the main air stream. The difference in the partial pressures is a measure of the driving force for mass transfer. In superheated vapor evaporation partial pressure differences do not occur. Wenzel and White (20, 21) have postulated that the temperature a t the interface is higher than the saturation temperature corresponding to the operating pressure of the equipment. In other words, the liquid is superheated with respect to the operating pressure of the equipment. A . degree of liquid superheat of t'he order of a few hundredths of a degree Fahrenheit would be sufficient to provide adequate vapor pressure increase to account for the mass transfer. Technical difficulties make it, difficult, however, to measure such small temperature increases in a fluid film. TheirThe investigations of \Venae1 et a [. (80. 21) were limited t,o high pressure operation which would find very limited application because of the more expensive equipment required, the higher operating temperatures, and because operation would necessarily ha...