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An awareness of increasing climate and health problems has driven the development of new functional and affordable soot-oxidation catalysts for stationary sources, such as fireplaces. In this study, Al(OH)3, water glass and acidic aluminium phosphate binder materials were mixed with soot-oxidation catalysts. The effect of the binder on the performance of the Ag/La-Al2O3 catalyst was examined, while the Pt/La-Al2O3 catalyst bound with Al(OH)3 was used as a reference. Soot was oxidised above 340 °C on the Ag/La-Al2O3 catalyst, but at 310 °C with same catalyst bound with Al(OH)3. The addition of water glass decreased the catalytic performance because large silver crystals and agglomeration resulted in a blockage of the support material’s pores. Pt/La-Al2O3 bound with Al(OH)3 was ineffective in a fireplace environment. We believe that AgOx is the active form of silver in the catalyst. Hence, Ag/La-Al2O3 was shown to be compatible with the Al(OH)3 binder as an effective catalyst for fireplace soot oxidation.

Exhaust gas aftertreatment systems play a key role in controlling transportation greenhouse gas emissions. Modern aftertreatment systems, often based on Pd metal supported on aluminum oxide, provide high catalytic activity but are vulnerable to sulfur poisoning due to formation of inactive sulfate species. This paper focuses on regeneration of Pd-based catalyst via the decomposition of alumina-supported aluminum and palladium sulfates existing both individually and in combination. Decomposition experiments were carried out under hydrogen (10% H2/Ar), helium (He), low oxygen (0.1% O2/He), and excess oxygen (10% O2/He). The structure and composition of the model catalysts were examined before and after the decomposition reactions via powder X-ray diffraction and elemental sulfur analysis. The study revealed that individual alumina-supported aluminum sulfate decomposed at a higher temperature compared to individual alumina-supported palladium sulfate. The simultaneous presence of aluminum and palladium sulfates on the alumina support decreased their decomposition temperatures and led to a higher amount of metallic palladium than in the corresponding case of individual supported palladium sulfate. From a fundamental point of view, the lowest decomposition temperature was achieved in the presence of hydrogen gas, which is the optimal decomposition atmosphere among the studied conditions. In summary, aluminum sulfate has a two-fold role in the regeneration of a catalyst—it decreases the Pd sulfate decomposition temperature and hinders re-oxidation of less-active metallic palladium to active palladium oxide.

Emission regulations and legislation inside the European Union (EU) have a target to reduce tailpipe emissions in the transportation sector. Exhaust gas aftertreatment systems play a key role in low emission vehicles, particularly when natural gas or bio-methane is used as the fuel. The main question for methane operating vehicles is the durability of the palladium-rich aftertreatment system. To improve the durability of the catalysts, a regeneration method involving an efficient removal of sulfur species needs to be developed and implemented on the vehicle. This paper tackles the topic and its issues from a fundamental point of view. This study showed that Al2(SO4)3 over Al2O3 support material inhibits re-oxidation of Pd to PdO, and thus hinders the formation of the low-temperature active phase, PdOx. The presence of Al2(SO4)3 increases light-off temperature, which may be due to a blocking of active sites. Overall, this study showed that research should also focus on support material development, not only active phase inspection. An active catalyst can always be developed, but the catalyst should have the ability to be regenerated.