Karen J. Buechler

Rapid solar-thermal dissociation of natural gas in an aerosol flow reactor

A solar-thermal aerosol flow reactor process is being developed to dissociate natural gas (NG) to hy drogen (H2) and carbon black at high rates. Concentrated sunlight approaching 10 kW heats a 9.4 cm long×2.4 cm diameter graphite reaction tube to temperatures ~2000 K using a 74% theoretically efficient secondary concentrator. Pure methane feed has been dissociated to 70% for residence times less than 0.1 s. The resulting carbon black is 20–40 nm in size, amorphous, and pure. A 5 million (M) kg/yr carbon black/1.67 M kg/yr H2 plant is considered for process scale-up. The total permanent investment (TPI) of this plant is

Effects of promoters on the product quality of nanophase SiC/α-Si3N4 composite powders synthesized through carbothermal reduction nitridation

12.7 M. A 15% IRR after tax is achieved when the carbon black is sold for

Solar-thermal dissociation of methane in a fluid-wall aerosol flow reactor

0.66/kg and the H2 for

Novel Processing to Produce Polymer/Ceramic Nanocomposites by Atomic Layer Deposition

13.80/GJ. This plant could supply 0.06% of the world carbon black market. For this scenario, the solar-thermal process avoids 277 MJ fossil fuel and 13.9 kg-equivalent CO2/kg H2 produced as compared to conventional steam-methane reforming and furnace black processing.

Solar-thermal fluid-wall reaction processing

The effect of additives is investigated for the carbothermal reduction synthesis of nanophase silicon carbide/silicon nitride composite powders. Mixtures of silica, carbon, seed silicon nitride, and additive are reacted in a thermogravimetric analyzer. The mass loss information combined with compositional and spectroscopic analysis allows product quality (morphology, surface area, α-Si3N4 and β-SiC contents, oxygen content, etc.) information to be obtained. It was observed that all of the additives used in this study increased the reaction rate. Lithium carbonate produced a silicon nitride/silicon carbide composite that was not significantly different from experiments without promoter. However, the product quality was severely affected in other instances.