Reaction Kinetics in Fractals

EZEQUIEL V ALBANO

Enciclopedia of Complexity and System Science.

Springer Verlag

Lugar: Heildelberg; Año: 2009; p. 7565 - 7582

Processes involving reaction among atoms, molecules,and particles in general, are ubiquitous both in natureand in laboratories. After the introduction of the conceptof fractals by B. Mandelbrot in the 1980s, it hasbeen realized that a wide variety of reactions take placein fractal media, leading to the observation of anomalousbehavior, i. e. the so called “fractal reaction kinetics”. The study of this subject has receivedconsiderable theoretical attention anda huge numerical effort has been made to improve its understanding. Furthermore, amongthe practical examples of fractal reaction kinetics onecan quote exciton annihilation in composite materials,chemical reactions in membranes pores, charge recombinationin colloids and clouds, coagulation, polymerizationand growth of dendrites, etc. Anotherscenery for the study of reaction kinetics in fractals isin the field of heterogeneous catalysis. In fact, it is wellknown that most catalysts are composed of small, catalyticallyactive particles, supported by highly porous (fractal)substrates. So, it is not surprisingthat this field of research has become particularly activedue not only to its practical and technological relevance,but also to the occurrence of quite interesting andchallenging phenomena such as irreversible phase transitions,oscillatory behavior, chaos and stochastic resonance,propagation and interference of chemical waves,interface coarsening, metastability and hysteretic effects,etc.