Том 59, № 11 (2019)

Copper (Cu), a kind of resourceful and low-cost transition metal has attracted a great deal of attention in recent years. Owing to the efficient catalytic activity of Cu nanoparticles (NPs), these particles are perfect candidates as dehydrogenation catalysts, especially in transforming alcohol to carboxylic acid. However, Cu nanoparticles are inclined to agglomerate and inactivating in the catalytic process. As a consequence, it is important to grasp some knowledge of dehydrogenation mechanism and the reason of deactivation, and modification the Cu catalyst properly to improve the catalyst performance. In this study, choosing novel supports and building multimetallic systems are considered good choices. Simultaneously, the synthetic methods of Cu-based catalysts have been discussed concisely. In summary, this review paper has put forward the development and prospects of Cu-based catalysts. We believe that this article will facilitate researchers to accelerate the development of Cu-based catalysts in dehydrogenation process in the future. In addition, dehydrogenation process is particularly important in petroleum processes, this article is also beneficial to the basic research of petrochemical industry.

Abctract

The aim of this work is to explore the floculation behavior of asphaltenes (extracted from a deposit recovered from a Hassi-Messaoud oil well) in solution in toluene according to the polarity of the flocculating medium. The flocculation thresholds related to the addition of two flocculating agents of different polarities (n-heptane and acetone) for three asphaltenic concentrations are obtained by means of near infra-red absorption spectrophotometry. The Hildebrand solubility parameters of the flocculated asphaltenic fractions are deduced using the Donnagio method based on the Flory−Huggins theory. The results obtained indicate that the interactions between the flocculated asphaltenic molecules within the toluene/acetone mixture are weaker than those in the toluene/n-heptane mixture.

This study investigates the equilibrium adsorption of asphaltene onto several nanoparticles (NiO, MgO, Fe₃O₄) with different surface chemistry at various temperatures by UV-Vis spectroscopy. The NiO had acidic surface; however the MgO and Fe₃O₄ had basic and amphoteric surfaces respectively, which were determined by titration method. The isotherm data of the nanoparticles were best modeled by Langmuir model that indicated monolayer asphaltene adsorption onto the nanoparticles. The maximum asphaltene adsorption capacities of the nanoparticles were obtained at minimum temperature (25°C) in the range of 0.6364–1.0545 mg/m² that decreased in the order of NiO > MgO > Fe₃O₄. The results confirm the potential application of nanoparticles with acidic surface for adsorption and removing of asphaltene. Moreover, the thermodynamic parameters at different temperatures showed that the adsorption of asphaltene onto the nanoparticles was spontaneous (ΔG⁰ < 0), exothermic (ΔH⁰ < 0) and physical (2.1< |ΔH⁰| <20.9 kJ/mol).

The influence of the morphology of cation-exchanged zeolite catalysts synthesized from domestic NaX zeolites on the main indicators of the alkylation reaction of isobutane with butylenes has been studied. It has been found that the catalyst preparation conditions have no substantial effect on the catalyst surface structure. The optimum indicators of the alkylation reaction (98–100 wt % conversion of butylenes, of the alkylate yield close to the theoretical yield of 99–100 wt %, TMP selectivity maintained at a level of 72 wt %, and C_8-others not exceeding 1.5 wt %) are achieved at the catalyst particle size in two ranges, below 0.8 and/or above 3.5 μm.

Hierarchical composite materials based on ordered aluminosilicates of the Al–MCM-41 type and halloysite nanotubes (HNTs) with different Al–MCM-41/halloysite weight ratios have been synthesized and studied as components of supports of platinum catalysts for the isomerization of the C₈ aromatic fraction of reforming. At each synthesis stage, the materials have been characterized by transmission electron microscopy (TEM), low-temperature nitrogen adsorption, X-ray fluorescence analysis, X-ray diffraction (XRD) analysis, and temperature-programmed desorption of ammonia (NH₃-TPD). Catalyst systems with an Al–MCM-41/HNT weight ratio of 90 : 10 wt % have shown the highest efficiency in xylene isomerization providing a higher conversion of ethylbenzene and m-xylene than the conversion provided by the HNT-based catalyst. It has been found that the synthesized catalysts exhibit a higher selectivity for the target product of the process—p-xylene—than the selectivity of a commercial counterpart in a temperature range of 360–440°C. The maximum p-xylene selectivity (70%) has been achieved in the presence of a Pt/Al–MCM-41/HNT(90 : 10)/Al₂O₃ catalyst at 360°C.

The acylation of o-cresol with pyromellitic dianhydride (PMDA) has been experimentally studied. The optimum conditions of the acylation reaction of o-cresol with PMDA have been determined. The synthesis has been performed in o-cresol melt at 120°C for 30 h at a reactant molar ratio of PMDA : o-cresol : SnCl₄ = 1.0 : 4.1 : 2.0. The yield of 3,3,7,7-tetrakis(3-methyl-4-oxyphenyl)pyromellitide is 62.0% of the theoretical value. The structure of the target synthesis product has been proven by instrumental methods, namely, elemental analysis; thin layer chromatography (TLC); UV, IR, and ¹H NMR spectroscopy; DSC; and high-performance liquid chromatography coupled with mass spectrometry (HPLC/MS). The revealed properties of 3,3,7,7-tetrakis(3-methyl-4-oxyphenyl)pyromellitide allow it to be recommended as a tracer for oil reservoir evaluation.

Effect of the chemical composition of catalysts for synthesis gas conversion to liquid olefins (carbon fiber-supported iron catalyst (Fe/CF) with promoting additives) and monohydric fatty alcohols (Fe–Co/C carbon-containing composite catalysts) on the main synthesis parameters has been studied. Characteristics of the pore structure and the morphology of test samples of catalysts for the synthesis of liquid olefins and monohydric fatty alcohols have been determined. It has been found that the introduction of promoters leads to significant changes in the characteristics of the pore structure of Fe/CF catalysts, in particular, to an increase in the surface area and average pore diameter of the catalyst. The highest efficiency for liquid olefins is achieved in the presence of a 15%Fe + 1%K/CF catalyst containing 15% Fe₂O₃ and 1% K₂O. The study of synthesis gas conversion to monohydric alcohols has revealed that, for a 20%(Fe–Co)/C catalyst, the optimum ratio is Co : Fe = 1 : 1. This catalyst has a large specific surface area and provides the highest yield of liquid products, the highest efficiency for them, and a high selectivity for monohydric aliphatic fatty alcohols.

Laboratory studies have been conducted to explore the possibility of obtaining poly-α-olefin oil PAO-20 under flow conditions on the basis of the domestic industrial octene fraction of α-olefins. The features of cationic oligomerization have been revealed by varying the catalyst concentration and the reaction temperature; process parameters to ensure the maximum yield of desired target product have been determined.