Heat of combustion ( Btu/ft 3, Btu/lb, kJ/kg)įollow the links below to get values for the listed properties of hydrogen at varying pressure and temperature: Latent Heat of Evaporation at boiling point ( Btu/lb, J/kg)įreezing or Melting Point at 1 atm ( oF, oC) Thermal Conductivity ( Btu/hr ft oF, W/m oC)īoiling Point - saturation pressure 14.7 psia and 760 mm Hg - ( oF, oK) Gas constant - R - ( ft lb/lb oR, J/kg oC) Specific Heat - c p - ( Btu/lb oF or cal/g oC, J/kgK) They’d like to reduce the use of noble metals such as ruthenium, and optimize the catalyst so that it can selectively make only specific fuels.Density of liquid at atmospheric pressure ( lb/ft 3, kg/m 3)Ībsolute Viscosity ( lb m/ft s, centipoises) However, the group still faces a few challenges. When the group tested their catalyst in the lab, they found that the yield for fuels such as ethane, propane and butane was much higher than their previous catalyst. The hydrogen then spills onto the iron shell, which makes the carbon dioxide more reactive. He suspects the ruthenium makes hydrogen chemically ready to bond with the carbon from CO 2. “It is something about the structure specifically that helps the reactions along.”Ĭargnello thinks the two catalysts act in tag-team fashion to improve the synthesis. Then we showed that once we do that, hydrocarbon yields improve tremendously,” Cargnello said. “That’s when we began to engineer this material directly in a core-shell configuration. Without this collaboration, Cargnello said they would not have discovered the optimal structure. SLAC’s sophisticated X-ray characterization technologies helped the researchers visualize and examine the structure of their new catalyst. The team did not set out to create this core-shell structure but discovered it through collaboration with Simon Bare, distinguished staff scientist, and others at the SLAC National Accelerator Laboratory. It improves the process start to finish.” “This structure activates hydrocarbon formation from CO 2. “This nugget of ruthenium sits at the core and is encapsulated in an outer sheath of iron,” said Aisulu Aitbekova, a doctoral candidate in Cargnello’s lab and lead author of the paper. (Catalysts induce chemical reactions without being used up in the reaction themselves.) The team succeeded by combining ruthenium and iron oxide nanoparticles into a catalyst. Butane is a common fuel in lighters and camp stoves.Ĭargnello thought completing both steps in a single reaction would be much more efficient, and set about creating a new catalyst that could simultaneously strip an oxygen molecule off of CO 2 and combine it with hydrogen. Propane is commonly used to heat homes and power gas grills. Ethane is a close relative of natural gas and can be used industrially to make ethylene, a precursor of plastics. The simplest of these fuels is methane, but other fuels that can be produced include ethane, propane and butane. The first step reduces CO 2 to carbon monoxide, then the second combines the CO with hydrogen to make hydrocarbon fuels. Previous efforts to convert CO 2 to fuel involved a two-step process. One such product is olefins, which can be used in a number of industrial applications and are the main ingredients for plastics. The group is also developing ways to make other beneficial products, not just fuels. Next steps include trying to reduce harmful byproducts from these reactions, such as the toxic pollutant carbon monoxide. Much work remains, however, before average consumer will be able to purchase products based on such technologies. “One can imagine a carbon-neutral cycle that produces fuel from carbon dioxide and then burns it, creating new carbon dioxide that then gets turned back into fuel,” said Matteo Cargnello, an assistant professor of chemical engineering at Stanford who led the research, published in Angewandte Chemie.Īlthough the process is still just a lab-based prototype, the researchers expect it could be expanded enough to produce useable amounts of fuel. While not a climate cure-all, the advance could significantly reduce the near-term impact on global warming. Several recent studies have shown some success in this conversion, but a novel approach from Stanford University engineers yields four times more ethane, propane and butane than existing methods that use similar processes. Aisulu Aitbekova, left, and Matteo Cargnello in front of the reactor where Aitbekova performed much of the experiments for this project.
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