Nanocatalysis: Mature Science Revisited or Something Really New? .Schlgl ,et al (2004)

Summary

UNIVERSITY OF BARCELONA GABRIEL MARIO

1. Nanotechnology and Catalysis

In material Science, the properties recognition depends of the physics origins and the size of the

molecules, including the electronic structures that allows the transition from micro to

nanostructures. Worldwide a lot of projects, founding, researches and published papers, have

been determinate that catalysis is a strong field linked to nanoscience, with variety of materials

and applications, for new functional analytical techniques. This link allows tailored size individual

objects with needs for function and the physical multiscale phenomenon. One of the requirements

is the selforganization of the nanoparticles, when we can determinate the relation of the

interactions between particles and the interactions with the environment, to control them and

obtain an hierarchical structures. To do this, it is relevant to use theoretical tools for the

combinations of various levels that obtain a functional analysis systems from nanoscopic objects

with functional and assembly of molecular building blocks properties. The hierarchical structures

works in scales of sub 100nm, with a wide field of applications and products obtained of catalyst

material science and chemical process engineering.

2. Size effects in Heterogeneous Catalysis

Work with small particles is considered long time ago The technical catalysis, where the first

objective is to reduce the size of the particles to maximize the area exposed to the reactants, also

reduce the specific cost per function. Other major aspect is the optimization form of the basis

using active materials, with different functional dimensions, that origins the catalysis phenomena

for several scales of length and time, in some cases simultaneously. This process contains 3 types

of heterogeneous catalysis: Surface chemical, transport and solid state. The phenomena

determines the interconnection process of the substrate-active site interactions, from the reactants

and the products. Another approach is the chemical reactivity function from reversible

transformations of the nano object to characterize it and to use it in some applications as ensure

the stability. The nanoparticles properties are in the interface when we have a molecular and bulk

Nanocatalysis: Mature Science Revisited or Something Really New? .Schlgl ,et al (2004)

Summary

UNIVERSITY OF BARCELONA GABRIEL MARIO

system, determining the presence of the clusters coordinately unsaturated (CUS), that are

considered part of the local sites of electronic structures, significant for small structures, identifying

the average ground state electroninc structure modification of collective excitation of metallic

character structures. These electronic properties are defined by fine tuning of the optimization of

chemisorption and the molecule activation. CUS can determinate the relation between size and

the function in active materials in metastable non-equilibrium state, also CUS appears in three

dimensions generated by the roughness, morphology and the selectivity of the catalytic reactions

inside of the matrix (active sites) in metastable conditions. They are exists two main conditions

that determinate the dynamics of the surface that are the size and the catalytic function, that build

the kinetic barrier of equilibrium.

3. Catalysis Synthesis: The Challenge

Most of the kinetic boundary conditions techniques are determined by prepared catalyst methods

that characterized functional and non-predictable properties, changing the reaction environment

and using protective non-aqueous ligands to determine reactions pathways for active

nanoparticles.

4. Nanocatalysis: A vision

Nanoscience can control and determinate the functional properties and nanocatalysis could be

considered as hierarchical system with active structural system units with assembling strategies to

reach the nanoscale, obtained by catalyst interactions between the reactant and also with the

reactor, to do in situ functional characterization of the identification of active sites and the

determination of the synthetic strategies, trough kinetics experiments of empirical catalyst

optimization libraries of the parameter space of each material and the conditions.