Thermoelectric elements of both P-type and N-type lead tellurides having unique characteristics including, particularly in the case of the P-type, a figure-of-merit 90% above that of the best commercial P-type element, are produced by a new process involving as key steps chill casting, cold pressing and sintering to 85-90% theoretical density under protective atmosphere.
A continuous multistage catalytic conversion system for upgrading lower olefins comprising first adaibatic catalytic bed reactor means containing an acidic zeolite solid catalyst; means for feeding light olefinic gas directly to the first reactor without addition of separate diluent or recycle streams; means for operating the first reactor under olefin partial conversion conditions at elevated temperature to control adiabatic temperature increase; interstage quench means for injecting a liquid coolant directly into first stage effluent for reducing the temperature thereof and protecting downstream catalyst; second catalytic bed reactor means for receiving cooled first stage effluent with injected liquid coolant and further converting the olefins over a metallic zeolite catalyst having a metal ethene oligomerization component; means for cooling and recovering heavier liquid hydrocarbon product from the second reactor effluent; and means for recovering liquid coolant from the second effluent for recycle to the interstage quench means.
Thermoelectric material contains one or more than one element selected from the transition metals and the rare earth metals, and the element promotes the amorphous phase in the thermoelectric material so as to increase the figure of merit.
Oxide is undesirably grown on the surface of grains of thermoelectric alloy, and the resistivity of the thermoelectric alloy is decreased due to the oxide; however, the oxide is reduced with hydrogen gas before the powder is solidified, and the pieces of thermoelectric alloy produced from the oxygen-free powder achieve a large figure of merit.
A technique for forming from staring precursors at the molecular level, a sultant thermoelectric material with a reduced thermal conductivity. All staring precursors are dissolved in solution, reduced to remove oxygen, and then combined into a single solution to yield specific stoichiometric ratios. A sol and then a gel is formed, which supercritical solvent extraction is performed upon so as to yield a material having two level porosity and a maximum of a factor of three reduction in thermal conductivity.
A thermoelectric device using a pressed and sintered P-type semiconductor material connected to a crystalline N-type semiconductor material exhibits an unexpectedly high figure-of-merit, Z, and improved mechanical strength.
