Search

In recent decades, direct alcohol fuel cells (DAFCs) have been extensively studied and considered as possible power sources for portable electronic devices and vehicles in the near future.1 The application of methanol is limited due to its high volatility and toxicity,2,3 although it is relatively easily oxidized to CO2 and protons. [ABSTRACT FROM AUTHOR]

Hydrogen fuel cells and direct methanol fuel cells are becoming increasingly attractive power sources because of the high conversion efficiencies and low pollution and the use for mobile and stationary applications such as on-board electric power sources for advanced propulsion systems, nonpolluting electric vehicles, and portable devices. [ABSTRACT FROM AUTHOR]

In the field of heterogeneous catalysis, the control of the characteristics of supported particles is one of the main objectives of all researchers who want to establish relationships between structure and reactivity. Catalysts with the same macroscopic composition may exhibit very different catalytic performances because of large variations of the active site properties at the nanometer scale. [ABSTRACT FROM AUTHOR]

During the pyrolysis and gasification of fossil and nonfossil materials such as coals and biomass, various organic compounds are produced. Many of these decomposition products have been considered a source of major concern for plant operations and product utilization, especially their emission into the environment which is seen as a major public concern.1-5 [ABSTRACT FROM AUTHOR]

The importance of particle size on the catalytic properties of metals was recognized from the early days of catalysis when the concept of active sites ("particular atoms or groups of atoms on the surface of solids responsible for their catalytic activity and selectivity of") was introduced in 1925 by H. S. Taylor.1,2 [ABSTRACT FROM AUTHOR]

Nanotechnology has been employed in catalysis for many years. For example, Sinfelt et al. have carefully developed and analyzed composite nanoparticles employed in petroleum refining.1-3 Goodman et al. have examined the roles of nanoparticles in catalysis under well-controlled environment.4 Gates and others have employed molecular nanoparticles in catalysis.5 The benefits of applying nanotechnology to catalysis include improved activity, lifetime, resistance to poisoning, and other novel abilities such as catalyzing the growth of carbon nanotubes. These improvements and novelties cannot always be achieved with catalysts prepared by other methods. [ABSTRACT FROM AUTHOR]

Nanoparticles of precious metals have been routinely used in heterogeneous catalysis for more than half a century. Zeolites with a well-defined regular network of nanopores and nanocages were introduced by the Mobil company in 19641 because their superior acidity enables them to better catalyze hydrocarbon conversions involving carbenium ion intermediates, such as isomerization, dehydrocyclyzation, and cracking. [ABSTRACT FROM AUTHOR]

In recent years, transition metal oxide structures have garnered considerable attention due to their unique properties. Among the numerous transition metal oxides, tungsten oxides have been of special interest because of their distinctive characteristics that have led to a number of applications and promise further developments. Such applications include gas and humidity sensors, optical devices, electrochromatic windows, catalysts, and many more.1-6 [ABSTRACT FROM AUTHOR]

Catalytic materials are widely used in industrial chemical processes. However, challenges remain to maximize their efficiency, to keep their stability and activity over a long operating period, and to achieve re-usability by regeneration for cost reduction and environmental considerations.1 Sulfate ion modified metal oxides, such as sulfated zirconia (SZ) and zeolites, are two important solid catalysts in acid-promoted catalytic reactions, such as alkylation, dehydration, isomerization and cracking, etc.2 In particular, they are the candidates for potential replacement of the liquid acid catalysts, such as hydrofluoric acid or sulfuric acid in commercial gasoline refining processes. Modified complex oxides are good candidates due to their strong acidity. [ABSTRACT FROM AUTHOR]

Catalysis has a tremendous impact on the national economy as one-third of material U.S. GNP involves a catalytic process somewhere in the production chain.1 Catalytic technologies are well established throughout the economy, particularly in petroleum refining, emissions and pollution control (including energy production), polymers and plastics, pharmaceuticals and fine chemicals, and basic chemicals.2 The utilization of heterogeneous catalysts in these areas of chemical industry is certain to increase as environmental and economic pressures drive the movement toward clean, selective chemical processes.2 Similarly, developing new catalysts for more efficient, cost-effective processes will be especially important for growing industries involved in the potential development of a hydrogen economy.3,4 [ABSTRACT FROM AUTHOR]

Although gold in bulk has often been regarded as poorly active as a catalyst, Haruta et al. found in the late 1980s and the early of 1990s that the gold particles deposited on selected metal oxides exhibit surprisingly high catalytic activity for CO oxidation at low temperature.1,2 Now, an extensive body of literature describing the CO oxidation ability of gold nanoparticles supported on various metal oxides, such as TiO2,3-15 Fe2O3,1,16 CO3O4,1 NiO,1 SiO2,17 ZrO2,18,19 and Al2O3,20 has appeared.21-30 The catalytic activities of gold catalysts depend on many factors. Among them, the variation in the properties of support oxides gives rise to much of the variability in supported gold catalysts, for example the effect of isoelectronic point (IEP) upon deposition of gold species or the role of the oxide reducibility in effecting the transfer of oxygen between the support and the gold nanoparticles. The focus of this chapter is the review of our recent research on the synthesis and characterization of tailored nanostructured supports for the assembly of ultrasmall gold nanoparticles for catalysis applications. [ABSTRACT FROM AUTHOR]

The discovery in the 1980s that finely supported divided nanoparticles of gold could act as catalysts for reactions at lowtemperatures has to be one of the most fascinating recent observations in chemistry, since most consider gold to be an unreactive metal. Gold for a long time had been considered to be a relatively inert material and particularly unpromising as a catalyst. In particular, due to its stability under most conditions it is really surprising that it can be a highly effective oxidation catalyst. Consequently, a large number of experimental and theoretical studies are being undertaken to try to elucidate the nature of this interesting catalytic activity. This recent research has been reviewed by Haruta,1-5 Bond and Thompson,6,7 Bond,8 Thompson,9 Freund and coworkers,10 Cortie,11 Hashmi,12 Hutchings13-15 and Hutchings and Scurrell.16 It should be noted that copper and silver (both in the same triad of the periodic table as gold) are used in many large scale catalytic processes, and it has been known for many years that the preparation of active catalysts with copper and silver requires the metal to be well dispersed on a support. Hence, there should not be so much surprise when the same is observed for gold, but because gold was considered to be inert few experimental studies explored this area until the seminal studies of Haruta17 who discovered the high activity of gold for CO oxidation at sub-ambient temperature. This new discovery brings with it the opportunity that gold, in an appropriate form, is perhaps the most interesting metal in the Periodic Table with respect to table its potential to act as a catalyst. [ABSTRACT FROM AUTHOR]

One of the greatest challenges in the advancement of nanotechnology is the design of engines for nanoscale devices. Previous work focused on using external electric and magnetic fields to move nanoscale objects. For example, electric fields are commonly used to move colloidal silica particles1 and other mesoscale objects.2 Dielectrophoresis was responsible for the movement and alignment of the colloidal spheres in the former. An external electric stimuli to individually addressable microfabricated electrodes on silicon surfaces was also responsible for moving small objects akin to the dielectrophoretic force where the generated electric field moved the colloidal spheres. [ABSTRACT FROM AUTHOR]

Oxide-supported metals play an important role in a wide variety of industrial chemical processes such as the catalytic treatment of automotive exhaust. The ability to exercise greater control over the interactions of molecules on metal surfaces will create new possibilities for pollution control and the provision of novel power sources. Furthermore, a deeper understanding of molecule surface interactions will present numerous opportunities for the design of nanocatalysts. [ABSTRACT FROM AUTHOR]

Worldwide in the past decade, nanoscience and nanotechnology has become a popular field for research and development. As an example to explain its potential significance, heterogeneous catalysis was cited as a successful application that has great benefits for society. Thus, it is reasonable to expect that the explosion in new developments in nanoscience and nanotechnologywould have a significant impact on the understanding, practice, and applications of catalysis. In this paper, a brief account is presented using selected examples to illustrate ways that these recent developments have advanced heterogeneous catalysis, both in terms of better control of heterogeneous catalytic processes, and of applying catalysis to developments in nanotechnology. [ABSTRACT FROM AUTHOR]