Aluminum Titanate Compositions for Diesel Particulate Filters

Abstract

Compositions in the mixed strontium/calcium feldspar ([Sr/Ca]O. Al 2 O 3. 2SiO 2)-aluminum titanate (Al 2 O 3. TiO 2) system have been investigated as alternative materials for the diesel particulate filter (DPF) application. A key attribute of these compositions is their low coefficient of thermal expansion (CTE). Samples have been prepared with porosities of >50% having average pore sizes of between 12 and 16µm. The superior thermal shock resistance, increased resistance to ash attack, and high volumetric heat capacity of these materials, coupled with monolithic fabrication, provide certain advantages over currently available silicon carbide products. In addition, based on testing done so far aluminum titanate-based filters have demonstrated chemical durability and comparable pressure drop (both bare and catalyzed) to current, commercially available, silicon carbide products.

Micro- and macroscopic thermal expansion of stabilized aluminum titanate

“…13 The composition was dried and then fired at temperatures exceeding 1450 • C, with both heating and cooling done in ambient atmosphere with rates not exceeding 5 • C/min. The specimens had the form of a rod with about 1 m length and 10 mm diameter.…”

Cation distribution of pseudobrookite-type titanates and their phase stability

“…Al 2 TiO 5 ceramics are applied to the materials of a diesel particulate filter because of their high thermal shock resistance. 5), 6) The mechanical strength can be improved by reducing the amount of grain boundary cracks by suppressing grain growth 7) because a sample with a large grain size tends to have a large amount of grain boundary cracks and low mechanical strength. However, this also brings about an increasing thermal expansion coefficient.…”

Porous MgTi2O5/MgTiO3 composites with narrow pore-size distribution: in situ processing and pore structure analysis

“…Corresponding to a growing diversity of biodiesel fuels and to severer environmental regulations, third-generation DPFs materials with low-thermal expansion, low-cost, high strength and high refractoriness will be demanded in the future. 5), 6) Several double oxides, such as mullite (3Al 2 O 3 ·2SiO 2 ), 2), 7) zircon (ZrSiO 4 ) 8) and aluminum titanate (Al 2 TiO 5 ), 9)12) are of particular interest as candidates of the third generation, due to their low thermal expansion coefficients among oxides. Among these candidates, Al 2 TiO 5 (AT) has been eagerly studied due to its high thermal shock resistance caused by the low-thermal expansion.…”