A series of composites containing nanoparticles of NiO (from 1 to 10% by weight per Ni), deposited on NORIT charcoal, was prepared by the decomposition of the Ni⁰ complex Ni(cod)₂ (cod = cis,cis-1,5-cyclooctadiene). Ni content in the composites was set by loading the appropriate quantities of the Ni(cod)₂ precursor. The catalytic activity of the composites was associated with the in situ generation of active sites due to a reduction in NiO, hence the composites could be stored in air without a loss in their catalytic performance. The composites were analyzed by powder XRD, TEM, XPS, and adsorption methods. The hydrogenation of quinoline was used as a reference reaction for studies of the influence of temperature, P(H₂), catalyst loading on the product yield, and for the selection of the composite possessing the highest performance. It was found that 3% Ni loading was the most optimal. This composite was used as an efficient catalyst for the hydrogenation of compounds with ethylene and acetylene bonds, nitro- and keto- groups as well as a series of substituted quinolines and analogs. The studied composites can be proposed as air-stable and efficient catalysts for the hydrogenation of a wide range of organic compounds.

A series of seven palladium-containing composites, i.e., four Pd/C and three Pd(OH)₂/C (Pearlman’s catalysts), was prepared using modified common approaches to deposition of Pd or hydrated PdO on charcoal. All the composites were tested in the catalytic hydrogenation of diene carboxylates with the isolated-ring scaffold, e.g., 5,6-dihydropyridine-1(2H)-carboxylates with 2-(alkoxycarbonyl)cyclopent-1-en-1-yl and hex-1-en-1-yl substituents at the C(4)-position. The performance of the composites was also studied via the hydrogenation of quinoline as a model reaction. The composites were characterized by transmission and scanning electron microscopy (TEM and SEM), powder X-ray diffraction, and low-temperature N₂ adsorption. It was found that the composites containing Pd nanoparticles (NPs) of 5–40 nm size were the most efficient catalysts for the hydrogenation of dienes, providing the reduced products with up to 90% yields at p(H₂) = 100 atm, T = 30 °C for 24 h. The method of Pd NPs formation had more effect on the catalyst performance than the size of the NPs. The catalytic performance of Pearlman’s catalysts (Pd(OH)₂/C) in the hydrogenation of dienes was comparable to or lower than the performance of the Pd/C systems, though the Pearlman’s catalysts were more efficient in the hydrogenation of quinoline.

The performance of a series of cobalt-based composites in catalytic amination of aromatic aldehydes by amines in the presence of hydrogen as well as hydrogenation of quinoline was studied. The composites were prepared by pyrolysis of Co^II acetate, organic precursor (imidazole, 1,10-phenantroline, 1,2-diaminobenzene or melamine) deposited on aerosil (SiO₂). These composites contained nanoparticles of metallic Co together with N-doped carboneous particles. Quantitative yields of the target amine in a reaction of p-methoxybenzaldehyde with n-butylamine were obtained at p(H₂) = 150 bar, T = 150 °C for all composites. It was found that amination of p-methoxybenzaldehyde with n-butylamine and benzylamine at p(H₂) = 100 bar, T = 100 °C led to the formation of the corresponding amines with the yields of 72–96%. In the case of diisopropylamine, amination did not occur, and p-methoxybenzyl alcohol was the sole or the major reaction product. Reaction of p-chlorobenzaldehyde with n-butylamine on the Co-containing composites at p(H₂) = 100 bar, T = 100 °C resulted in the formation of N-butyl-N-p-chlorobenzylamine in 60–89% yields. Among the considered materials, the composite prepared by decomposition of Co^II complex with 1,2-diaminobenzene on aerosil showed the highest yields of the target products and the best selectivity in all studied reactions.

A set of Pd-containing composites was prepared by the deposition of Pd on the following carriers: polyaniline (PANI); PANI doped by H₂SO₄; Norit GSX activated carbon or Aerosil (SiO₂) coated by PANI or by H₂SO₄-doped PANI; PANI after thermal treatment at 300 °C in an atmosphere of H₂. One sample was also prepared by the in situ polymerization of aniline in the presence of Pd²⁺· The decomposition of Pd was carried out via deposition from the solutions of Pd²⁺ salts or decomposition of Pd⁰ complex Pd₂(dba)₃, where dba is dibenzylideneacetone. The composites were studied by powder X-ray diffraction, transmission electron microscopy, IR and Raman spectroscopy. The hydrogenation of quinoline in the presence of composites was carried out; the catalytic performance of the composites was evaluated by the yield of 1,2,3,4-tetrahydroquinoline. It was found that the doping of PANI by H₂SO₄, inclusion of Norit GSX activated carbon as a component of the carrier or thermal treatment of PANI prior to the deposition of Pd led to significant increase in the catalytic performance of the composites in the hydrogenation of quinoline.

This study was aimed at elucidating the role of the carboneous component in Co–carbon-containing catalysts for the hydrogenation of organic compounds. A Co-C/SiO₂ catalyst was synthesized via pyrolysis of a Co(II) complex with 1,2-diaminobenzene on silica and subsequently irradiated with 2.3 MeV electrons, producing Co-C/SiO₂*. A comprehensive characterization using XRD, TEM, IR, and Raman spectroscopy indicated minimal structural changes in the cobalt nanoparticles and carboneous materials. However, the Raman analysis revealed a slight decrease in the structural defect content in the carboneous component upon irradiation, which could occur due to defect healing. The catalytic tests, including the hydrogenation of 26 compounds, demonstrated an enhanced performance of the irradiated catalyst in 17 cases. This performance improvement was attributed to a modification of the carboneous material. It could be concluded that the carboneous components in Co-C composites contributed to their catalytic performance, probably by modifying the electronic structure of Co nanoparticles. In turn, the results provide arguments against the supposition that hydrogenation occurs on the structural defects of the carboneous material.

Rhenium sulfide Re2S7 was obtained by reaction of KReO4 with sodium thiosulfate. Composition of the sulfide was determined by several independent methods and corresponded to formula Re2S7·3S. The material was characterized by powder XRD, TEM, SEM, EDX and XPS. It was shown that Re2S7 was X-ray amorphous and consisted of nanosized sheets, which formed aggregates of ca. 50-100 nm size. According to XPS data, Re2S7 predominantly contained Re4+, with smaller amounts of Re+5 and Re+6; the peaks of sulfur could be assigned to S2-, S22-, elementary S and SO42-. It was found that Re2S7 could act as efficient catalyst for hydrogenation of alkene, alkyne functions, nitro-group and a series of substituted quinolines and isoquinolines. Unique tolerance or Re2S7 to C-I and C-Br bonds was revealed, allowing to prepare iodo-containing tetrahydroquinolines in multigram scale. In addition, hydrogenation of thiophenes and benzothiophenes in presence of Re2S7 could be performed, leading to isolation of the respective derivatives of tetrahydrothiophene and dihydrobenzthiophene in multigram scale.