I suggested here pulsed laser light to evaporate the solid reactant (metal, graphite...)http://www.chemicalforums.com/index.php?topic=72951.msg280320#msg280320
but a xenon arc lamp
does it faster and cheaper.
Consuming 150W to 20kW, they convert >50% to broadband light. Their colour and tiny emission volume match >6000K, so a concentrator lets sublimate or evaporate any metal or metalloid, even graphite. They cost around 10k€ for 10kWe
and last few continuous years. Serve in cinema theatres and sunlight simulators.
The joined sketch has no uniform scale, nor does it show the probable focal plane between both optics. Some carrier gas and reactants blows at the window shall keep it cool and clean. Wavelengths that heat the lens and the windows or damage the products or reactants can be filtered away. The reactor is coupled with an important cooling and separation unit to reinject the carrier gas and reactants.
10kW light would sublimate 50mol/h
graphite, or 100mm3
/s: feed a Do=10mm Di=8mm tube at 3mm/s, or maybe a bunch of fibres.
3289K give 1kPa graphite vapour pressure, and most other elements are easier. The usual method estimates then 0.27mm/s sublimation speed, or 2s to volatilize the tube, consistent with 3mm/s feed and ~10mm hot tip.
A L=10mm D=10mm tip at 3289K radiates 2kW. This increases as T4
and the sublimation rate at some T28
, so a smaller hotter tip saves power: prefer a narrower thicker tube or a rod if light can be concentrated enough.
The rod (100W/m/K for hot graphite in plane direction) conduces 1kW away across 10mm drop but the feed speed brings much back. Steady gas (100mW/m/K when hot) conduces 0.2kW away from R=5mm at 3000K; convection increases this.
Sufficient reactant pressure lets the vapour atoms make the product rather than rebuild a solid - or take a semi-vacuum where vapour atoms can spread far enough. The evaporated atoms should collide a few times more often with a carrier gas (like argon) than with the reactant so they have thermalized.
The destruction rate of the product is difficult to predict, but Berthelot's synthesis uses harsher conditions and the fragile acetylene survives. By the way, Berthelot's simpler apparatus is worth trying on other reactants like propylene, butene... with a carrier gas. The xenon lamp setup is more caring with the gaseous compounds here.
If producing 24/7 a C4
, 3k€ electricity and 1k€ lamp wear make 2000kg a month
at perfect yield for a single reactor. Typical products (...if any) would be small and energetic: cyclopropenes, maybe bicyclobutanes, and similar with graphite, while metals and metalloids could couple reactants or make organometallics.
Marc Schaefer, aka Enthalpy