Wydział Chemii

Andrzej Gniewek

Anna M. Trzeciak

2009

Wiadomości Chemiczne

63

953-984

Naukowa

Polski

Artykuł

Wprowadzenie. Synteza koloidów metali. Chemiczne otrzymywanie nanocząstek. Zarodkowanie i wzrost nanokryształów. Zastosowania nanocząstek metali w katalizie. Stabilizacja nanocząstek. Nanocząstki palladu. Nanocząstki niklu. Nanocząstki kobaltu.  Nanocząstki żelaza. Epilog.

Transition metal nanoparticles (also called metal colloids or nanoclusters) areordered multi-atom sets characterized by a very small size, generally less than20 nm. They are intermediate species between single atoms and crystals of macrosco-pic dimensions [1ñ8]. Nanoparticles have been synthesized by a variety of methods.The most common synthetic procedures involve chemical reduction of transitionmetal salts or complexes. By the choice of reduction conditions (kind of the redu-cing agent, type of the stabilizing agent and the elementary reaction parameters liketemperature and concentration) it is possible to obtain colloids showing differentparticle sizes and morphologies. These two factors play a decisive role from thepoint of view of catalytic activity of nanoclusters.Palladium nanoparticles have been obtained by chemical reduction of PdCl2aqueous solution using pyrogallol, hydrazine or chromium(II) acetate as the redu-cing agent. All these systems have demonstrated a very high catalytic activity inimportant carbon-carbon bond forming reactions (methoxycarbonylation, Heck andSuzuki processes) carried out under mild conditions [48, 49]. Some of the CñCcoupling reactions have also been successfully catalyzed by nickel nanoparticles,however they require more harsh conditions [65, 66].Cobalt and iron nanoparticles present magnetic properties attractive for appli-cation of these materials as removable electronic media of high capacity, as well asbiosensors or magnetic probes for biological imaging and therapeutic use [9, 18].The extreme reactivity of nanoparticles, specifically towards oxygen and water, com-plicates their synthesis, however it is also beneficial in catalytic applications[16, 17]. Conversion of CO/H2 mixture to hydrocarbons, known as Fischer-Tropschsynthesis, representing one of the most important routes to fuels production, is cata-lyzed very effectively by iron and cobalt nanoparticles. Monometallic and bime-tallic cobalt nanoparticles are excellent catalysts of Pauson-Khand type couplingsleading to cyclopentanones [17].

metal nanoparticles, metal colloids, catalysis, C-C bond forming reac- tions, Fischer-Tropsch process

nanoczπstki metali, koloidy metali, kataliza, reakcje tworzenia wiπzaÒ CñC, reakcja Fischera-Tropscha

https://www.dbc.wroc.pl/dlibra/publication/3889/edition/3758/content?ref=desc