μm- and nm-Sized Catalytic Structures in Heat Sources for Thermoelectric Generators

Abstract

Micro- and nano-structural organization and its influence on the efficiency of catalysts used in the heat sources for permeable thermoelectric generators were investigated. Two types of catalyst were studied–elemental platinum on aluminum oxide granulate Pt/Al₂O₃ and mixed transition-metal catalyst on fibrous silicon dioxide Co–Cr–Pd–Sr/SiO₂. The distribution of active components in catalytic structures which contribute to the maximum combustion completeness of organic fuel in heat sources was investigated. Practically full conversion of hydrocarbons was achieved already with 1 mass.% of platinum in the Pt/Al₂O₃ catalyst with sub-μm- and nm-sized particles placed at the input of the gas-air mixture into the channel of the permeable thermoelement. The propane-butane conversion rate of 97% for the catalyst Co–Cr–Pd/SiO₂ with was further enhanced by addition of 0.5 mass.% of Sr. The catalytic centers are formed by CoCr₂O₄ nanocrystals (10 to 40 nm in size) with Pd promotor in form of single crystals on the fibrous SiO₂ matrix.