1,721,558 research outputs found
Nanostructured materials for advanced automotive de-pollution catalysts
No full textThe present paper reviews the current understanding of CeO 2-ZrO 2 mixed oxides as promoters of the three-way catalysts. Emphasis is given on the role of the synthesis and it is shown that by adopting an appropriate design of the CeO 2-ZrO 2 system, nanostructured materials of high thermal stability can be prepared that are suitable for next generation automotive converter
Infrared study of nitric oxide (NO) adsorption and conversion on CeO2-ZrO2 mixed oxide
No full textAn IR study of adsorption of NO- and CO-containing mixtures on a high-surface-area Rh/Ce0.5Zr0.5O2 mixed oxide is reported. At low temperatures, NO strongly interacts with surface oxygen. The presence of various NOx-containing species co-ordinated both to cerium and zirconium has been observed. The NOx storage capacity is mainly associated with the presence of zirconium sites. The extension of NOx storage strongly depends on the adsorption temperature, which is associated with the presence/absence of reactive surface oxygen species. Formation of N2O2- 2 as adsorbed species appears to be a possible key step in the mechanism for conversion of NO at low temperature
AEROGEL MATERIALS BASED ON METAL OXIDES AND COMPOSITES THEREOF
No full textPATENT RIGHTS FULLY GRANTED ON JANUARY 25th, 2012.
ABSTRACT: The present invention describes a new class of high porosity materials with aerogel properties, based on metal oxides and their composites, possessing a high surface area and a high pore volume distributed within a specific pore diameter range. The pore distribution is monomodal and the porosity of the material is greater than 80%, conferring aerogel properties thereon while the absence of micropores (pores less than 2 nm in diameter) confers a high thermal stability to these materials. The characteristics of the product, including a low, if not zero, macroporosity, confer on the material a low dustiness compared to conventional aerogels, thus enabling them to be used effectively in production cycles.
Based on this knowledge, the Nanoxer s.r.l, a UNITS spin-off has been funded. Nanoxed s.r.l has won the first award of the National Innovation Award 2007
Structural properties and thermal stability of ceria-zirconia and related materials
No full textThe use of CeO2-based materials in catalysis has attracted considerable attention in recent years, particularly in applications like environmental catalysis, where ceria has shown great potential. This book critically reviews the most recent advances in the field, with the focus on both fundamental and applied issues. The first few chapters cover structural and chemical properties of ceria and related materials, i.e. phase stability, reduction behaviour, synthesis, interaction with probe molecules (CO, O2, NO), and metal-support interaction - all presented from the viewpoint of catalytic applications. The use of computational techniques and ceria surfaces and films for model catalytic studies are also reviewed. The second part of the book provides a critical evaluation of the role of ceria in the most important catalytic processes: three-way catalysis, catalytic wet oxidation and fluid catalytic cracking. Other topics include oxidation-combustion catalysts, electrocatalysis and the use of cerium catalysts/additives in diesel soot abatement technology
Heterogeneous environmental catalysis - a gentle art:CeO2-ZrO2 mixed oxides as a case history
No full textMore than 20 years ago, C.Master used the term gentle – skill-full – art to define homogeneous catalysis. In the present paper, we show that, with the advances of knowledge of heterogeneous catalysis (CeO2-ZrO2 mixed oxides being taken as an example), this term can nowadays appropriately apply to heterogeneous catalysis as well. Thus, comprehension of the reaction mechanism and the appropriate choice of textural properties appear to allow true design of the properties of these catalytic nano-materials, in a similar fashion to the way in which ligands gently modify the activity of a metal centre in a homogeneous catalyst
On the role of oxygen storage in three-way catalysis
No full textThe role of the so-called oxygen storage and release capacity (OSC) in promoting the activity of noble metals in the three-way catalysts (TWCs) is critically discussed. It is shown that the promoting effects of CeO2 in the TWCs cannot be attributed to a simple redox type of effect according to the reaction CeO2 .tautm. CeO2 - x + x/2O2, since multiple and sometimes intriguing effects of CeO2 promoter have been obsd., particularly in the latest generation of TWCs contg. modified CeO2-ZrO2 mixed oxides
Redox behaviour of high surface area Rh-loaded Ce0.5Zr0.5O2 mixed oxide
No full textRedox behavior of high surface area Rh-loaded Ce0.5Zr0.5O2 mixed oxid
- …
