Plenary lecture 2: nanotechnology and heterogeneous catalysis
Authors: Karim H. Hassan
Venue: Proceedings of the 1st WSEAS international conference on Nanotechnology (2009)

Catalysis is the process in which the rate of a chemical reaction is increased by means of a chemical substance known as a catalyst. Catalysts can be either heterogeneous or homogeneous, depending on whether a catalyst exists in the same phase as the substrate. Biocatalysts are often seen as a separate group. Heterogeneous catalysts are those which act in a different phases than the reactants. Diverse mechanisms for reactions on surfaces are known, depending on how the adsorption takes place (Langmuir-Hinshelwood and Eley-Rideal). Heterogeneous catalysts are typically "supported," which means that the catalyst is dispersed on a second material that enhances the effectiveness or minimizes their cost. Nano is a Greek prefix which signifies a "billionth". An atom is smaller than a nanometer, but a a molecule is more -A dimension of 100 nanometers is important in nanotechnology, because under this limit one observes new properties of matter, primarily due to the laws of quantum physics. So catalytic properties could benefit from the synthesis of nanostructured material not through the preparation of nanoparticles with high surface to volume ratio and narrow size distribution but also through the possibility to produce nanoparticles with well defined morphology and surface structure. Nano-materials are more effective than conventional catalysts for two reasons. First, their extremely small size (typically 10-80 nanometers) yields a tremendous surface area -to volume ratio. Also, when materials are fabricated on the nanoscale, they achieve properties not found within their macroscopic counterparts. Both of these reasons account for the versatility and effectiveness of nano-catalysts. A lot of researches have been done on the application of nanoparticles in heterogeneous catalysis process, some of which and the state of art one will be reviewed in this lecture. Iso-paraffin production on nano-porous catalysts composed of zeolite, nano-porous Al2O3 and Ni-Mo/aAl2O3 showed that the catalyst composed of MFI zeolite selectivity produces propane and that composed of BEA zeolite can selectively produce isobutene whereas that composed of USY zeolite can selectively produce iso-paraffins in gasoline fractions. Pt/MgO catalysts were prepared by using wet impregnation method. Partial Oxidation of Methane (POM) to synthesis gas revealed that Pt particles have the size of less than 10 nm, the size of the support MgO is about 50-200 nm. Nanostellar has filed five broad patent applications for low cost nano catalysts that can be used for gasoline engine three-way catalyst, lean-burn diesel engine catalytic materials, fuel cell proton exchange membrane assemblies, and for the chemical and petrochemical industries. The low temperature nano-catalysts studies for water gas shift reaction showed that Au and Cu nanoparticles supported on the oxides, such as CeO2 and TiO2. display higher activity than the bulk materials and commercial catalysts. Remarkable selectivity is achieved in the cleavage of benzyl ethers using ball-shaped palladium nanocatalysts.