Obtaining of highly-active catalysts of unsaturated compounds hydrogenation by using supercritical carbon dioxide

Heterogeneous Dendrimer-Based Catalysts

“…Thus, PPI and PAMAM dendrimer network-based catalysts were developed, containing Rh, Ru, and Pd nanoparticles successfully applied for hydrogenation of phenols [ 122 , 127 , 412 ], aromatic [ 127 , 408 , 413 , 414 ], and unsaturated compounds under the moderate conditions (50–90 °C, 10–30 atm. of H 2 ) [ 123 , 128 , 241 , 287 , 409 , 415 ]. The main reaction products were the same as for dendrimer-based silica supported catalysts [ 193 , 396 ], and typical for the metal nature under the applied conditions; after hydrogenation of aromatic compounds and phenols in the presence of Rh and Ru containing catalysts, there were corresponding alkylsubstituted cyclohexanes, cyclohexanols, and dihydroxycyclohexanes [ 1 , 122 , 127 , 408 , 413 , 414 ].…”

“…The main reaction products were the same as for dendrimer-based silica supported catalysts [ 193 , 396 ], and typical for the metal nature under the applied conditions; after hydrogenation of aromatic compounds and phenols in the presence of Rh and Ru containing catalysts, there were corresponding alkylsubstituted cyclohexanes, cyclohexanols, and dihydroxycyclohexanes [ 1 , 122 , 127 , 408 , 413 , 414 ]. In the presence of Pd-containing catalysts, based on the dendrimer networks, styrenes and dienes were selectively converted to corresponding ethylbenzenes and monoenes with the aromatic ring or conjugated C=C or C=O double bonds remained untouched [ 123 , 128 , 241 , 287 , 409 , 415 ].…”

“…Herein, Rh catalysts, based on PAMAM dendrimers, revealed the highest activity in the hydrogenation of alkenes, such as 1-octene and, especially, styrene, and a noticeable negative dendritic effect was observed for catalysts on both PAMAM and PPI dendrimers. Pd catalysts appeared to be the most effective in the hydrogenation of conjugated dienes [ 415 ].…”

“… Dendrimers and linkers used for dendritic network synthesis [ 122 , 123 , 127 , 128 , 241 , 287 , 408 , 409 , 412 , 413 , 414 , 415 ]. Reprinted and adapted with permissions of Elsevier, from: Karakhanov, E. A.; Maximov, A. L.; Zakharyan, E. M.; Zolotukhina, A. V.; Ivanov, A. O. Palladium nanoparticles on dendrimer-containing supports as catalysts for hydrogenation of unsaturated hydrocarbons.…”

Synthesis of Supported Heterogeneous Catalysts by Laser Ablation of Metallic Palladium in Supercritical Carbon Dioxide Medium

“…In the work of Watkins et al, poly-4-methylpentene-1 or polytetrafluoroethylene was used as the carrier, and the dimethyl (cyclooctadiene-1,5) platinum complex, Pt(cod)Me 2 , served as a precursor [ 15 ]. In [ 16 ], palladium, rhodium, and platinum compounds were deposited to hollow nanospherical polystyrene; in [ 17 ], rhodium and palladium compounds were deposited on crosslinked dendrimers (polypropyleneimines and polyamidoamines). The obtained metal–carrier composites were active in the catalysis of various reactions: hydrogenation of unsaturated hydrocarbons [ 6 , 10 , 17 ], allyl alcohol [ 16 ], nitrophenol [ 5 ], methanol electrooxidation [ 9 ], Suzuki–Miyaura combination reaction [ 4 , 11 ], water shift reaction [ 3 ], etc.…”