Steven Bolaji Ogunwumi

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. INTRODUCTION Diesel particulate matter (PM) emissions pose serious health concerns and are under environmental regulation. Diesel filter after-treatment technology is currently used to remediate PM emissions. SiC and cordierite filters are two of the most viable solutions available for use today. Cordierite has a low coefficient of thermal expansion and can survive thermal shock in this application, but cordierite is limited by its low heat capacity. It is also susceptible to ash reaction during exceedingly high temperature applications [1]. SiC, on the other hand, has a lower thermal shock resistance and thus needs to be segmented. The segmentation increases manufacturing costs and is a concern because of potential mechanical integrity issues. Other issues with SiC have been reported recently and solutions have been implemented [2-3]. An alternate DPF candidate is a novel Aluminum Titanate (AT) ceramic oxide composite. The composition is highly refractory with a melting temperature exceeding 1500°C. The high heat capacity of the composition is an attribute that is beneficial for thermal management and allows the filter regeneration temperature to be low. Although the intrinsic coefficient of thermal expansion of aluminum titanate is quite high (CTE = >9*10

Thin zeolite laminates for rapid and energy-efficient carbon capture

Thin, binder-less zeolite NaX laminates, with thicknesses ranging between 310 to 750 μm and widths exceeding 50 mm and biaxial tensile strength in excess of 3 MPa, were produced by pulsed current processing. The NaX laminates displayed a high CO2 adsorption capacity and high binary CO2-over-N2 and CO2-over-CH4 selectivity, suitable for CO2 capture from flue gas and upgrading of raw biogas. The thin laminates displayed a rapid CO2 uptake; NaX laminates with a thickness of 310 μm were saturated to 40% of their CO2 capacity within 24 seconds. The structured laminates of 310 μm thickness and 50 mm thickness would offer low pressure drop and efficient carbon capture performance in a laminate-based swing adsorption technology.