Showing papers in "Petroleum Chemistry in 2019"
TL;DR: In this article, the influence of process parameters on the bio-oil yield and biooil upgrading was analyzed, where different S. obliques biomass to water ratios were liquefied at diverse temperatures ranging from 200 to 340°C under 5 MPa N2 gas atmosphere.
Abstract: The emerging fuel crisis necessitates a shift in focus towards alternative renewable forms, so that sustainable development can be achieved. Bio-oil is a promising alternative renewable source of energy which is a third generation bio-fuel. Algae are a popular candidate for bio-fuel production due to their high lipid contents, ease of cultivation and rapid growth rate. In this study, Hydrothermal liquefaction of Scenedesmus obliques biomass cultivated in photo-bio-reactor (PBR) from wastewater was studied. The influence of process parameters on the bio-oil yield and bio-oil upgrading was analysed. Different S. obliques biomass to water ratios (0.025, 0.05, 0.075 and 0.1 g/ml) were liquefied at diverse temperatures ranging from 200 to 340°C under 5 MPa N2 gas atmosphere. The influence of catalyst on bio-oil upgradation was studied at varying catalyst loading of the range 1–5 wt %. Bio-oil was analysed using Gas Chromatography Mass Spectroscopy (GC-MS) and Fourier Transform Infrared Spectroscopy (FTIR). Results showed a maximum bio-oil yield of 24.57 wt % at 300°C, 15 g/200 ml biomass load and 2.5 wt % NaOH at 60 min holding time. Also, it was found that the gas generated from liquefaction process contained 22 vol % Hydrogen gas, 18 vol % Carbon dioxide gas, 27 vol % Carbon monoxide gas, 22 vol % of methane gas and a small amount of other gaseous components (H2S). HTL bio-oil was upgraded and it resulted in 30.15 wt % yield with higher degree of C7−C21 range hydrocarbons in it.
31 citations
TL;DR: The problems of zeolite catalysis associated with the introduction of domestic technologies are considered in this article, with particular attention paid to works related to the use of alternative components of catalytic systems, new environmentally friendly materials that improve the quality of the fuels produced with their use.
Abstract: The problems of zeolite catalysis associated with the introduction of domestic technologies are considered. Particular attention is paid to works related to the use of alternative components of catalytic systems, the introduction of new environmentally friendly materials that improve the quality of the fuels produced with their use. The processes of catalytic cracking, processing of heavy petroleum residues, solid-acid alkylation, and synthesis of light olefins and the problems of renewable feedstock processing are discussed in detail.
23 citations
TL;DR: In this article, an analysis of the structure, synthesis, and physicochemical properties of zeolites of the MWW structural type is presented, and their similarities and differences have been evaluated.
Abstract: This review presents an analysis of the structure, synthesis, and physicochemical properties of zeolites of the MWW structural type. Various physicochemical characteristics of zeolites MCM-22, MCM-36, MCM-49, and MCM-56 (X-ray diffraction data, textural characteristics, morphology, IR and NMR data) have been discussed and compared, and their similarities and differences have been evaluated.
23 citations
TL;DR: In this article, a review discusses the achievements of the last five years in the field of using mass spectrometry for the analysis of crude oils and some oil refining products. And the capabilities and disadvantages of existing approaches are discussed.
Abstract: The review discusses the achievements of the last 5 years in the field of using mass spectrometry for the analysis of crude oils and some oil refining products. The presented materials are systematized according to properties of the analyzed compounds and ionization techniques used. The capabilities and disadvantages of existing approaches are discussed.
21 citations
TL;DR: In this paper, the experimental approaches used during the investigation of the structure, concentration, and properties of metal complexes of petroleum porphyrins and their free bases are systematized, and the capabilities and limitations of the used methods (mass spectrometric, spectroscopic (electron paramagnetic resonance, UV-visible electronic absorption spectroscopy, and X-ray techniques) as well as high-performance and gel penetration liquid chromatography) are discussed.
Abstract: The presented review considers the currently relevant methods for studying petroleum porphyrins. For this purpose, the experimental approaches used during the investigation of the structure, concentration, and properties of metal complexes of petroleum porphyrins and their free bases are systematized, and the capabilities and limitations of the used methods (mass spectrometric, spectroscopic (electron paramagnetic resonance, UV–visible electronic absorption spectroscopy, and X-ray techniques) as well as high-performance and gel penetration liquid chromatography) are discussed. Published approaches to the concentration, fractionation, and purification of petroleum porphyrins based on the extraction and chromatographic methods of recovery of chemical compounds from complex multicomponent mixtures are also analyzed.
20 citations
TL;DR: A review of the current state of research in the field of oil rheology is presented as the basis for quantitative characterization of oil flow in the pipeline system as mentioned in this paper, based on recent publications, a picture is presented of the dependence of the rheological properties of oils of various types on their composition.
Abstract: A review of the current state of research in the field of oil rheology is presented as the basis for quantitative characterization of oil flow in the pipeline system. Based on recent publications, a picture is presented of the dependence of the rheological properties of oils of various types on their composition. The features of the flow of waxy oils, including the problem of correct assessment and depression of the pour point, have been analyzed. The flow of crystallizing oil has been considered proceeding from the concept of oil as a viscoplastic thixotropic medium. It has been shown how the results of rheological studies can be used to solve technological problems, including the restart problem. The rheology of heavy oil has been considered on the basis of the strategic objective of reducing viscosity to a level that meets the requirements of its transport in existing pipeline systems. Various existing and promising ways to solve this problem are discussed. Particular attention is paid to the role of asphaltenes and the formation of emulsions and their importance in oil rheology.
18 citations
TL;DR: In this paper, the prospects for creating low-volume production technologies for reforming of natural and associated gases to liquid carbon-containing products based on the use of cheap nitrogen-rich synthesis gas have been analyzed.
Abstract: The prospects for creating low-volume-production technologies for reforming of natural and associated gases to liquid carbon-containing products based on the use of cheap nitrogen-rich synthesis gas have been analyzed. Processes for obtaining cheap nitrogen-rich synthesis gas and sustainable high-performance synthesis of liquid products based on it have been considered. Data on the conversion of nitrogen-rich synthesis gas to methanol, dimethyl ether, and higher hydrocarbons are presented. The main advantages of using nitrogen-rich synthesis gas have been pointed out, which are the capability of reformers to operate on-site, no need for expensive cryogenic devices for air separation, and reduction of the explosion risks during production.
16 citations
TL;DR: In this paper, hierarchical composite materials based on ordered aluminosilicates of the MCM-41 type and halloysite nanotubes (HNTs) with different MCM41/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.
Abstract: 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.
15 citations
TL;DR: In this article, the preparation and catalytic action of zeolites in the form of nanosized crystals are reviewed, and the progress and prospects of using nanosised zeolite in slurry reactors comprising three-phase systems, in which individual Zeolite particles are dispersed in a liquid medium, are considered.
Abstract: Studies on the preparation and catalytic action of zeolites in the form of nanosized crystals are reviewed. Examples of successful synthesis of nanosized zeolites of the FAU, MFI, BEA, and MOR structural types and their use in such processes of petroleum chemistry and refining as catalytic cracking, hydrocracking, hydroisomerization, oligomerization, transalkylation, conversion of methanol and acetone to olefins, and other processes are given. The progress and prospects of using nanosized zeolites in slurry reactors comprising three-phase systems, in which individual zeolite particles are dispersed in a liquid medium, are considered.
Keywords: nanosized zeolites, catalytic cracking, hydrocracking, transalkylation, slurry reactor
13 citations
TL;DR: In this paper, the effect of the natural minerals pyrite and hematite as a catalyst on the efficiency in destruction of the organic matter of Domanik rock, rich in organic matter, at a temperature of 300°C in a steam-carbon dioxide gas environment has been studied.
Abstract: The effect of the natural minerals pyrite and hematite as a catalyst on the efficiency in destruction of the organic matter of Domanik rock, rich in organic matter, at a temperature of 300°C in a steam–carbon dioxide gas environment has been studied. Compared with the original rock and a control experiment, the presence of the natural catalysts in the reaction system leads to an increase in both the amount of mobile hydrocarbons in the rock and the yield of extracts, in which the concentration of saturated hydrocarbons is increased by factors of 12 and 16 in the experiments with pyrite and hematite, respectively, and the asphaltene content is halved. The degradation processes of high-molecular-weight resinous–asphaltenic components and insoluble kerogen lead to the formation of lower n-alkanes and the structuring of asphaltenes to increase the degree of their carbonization, followed by the formation of insoluble substances of the carbene–carboid type appearing as a new dispersed solid phase in the products. The distinctive features of the structural composition of asphaltenes and carbenes–carboids have been revealed. The close composition of the products of hydrothermal–catalytic experiments suggests that pyrite and hematite exhibit similar catalytic properties under hydrothermal conditions.
13 citations
TL;DR: In this paper, the main advantages and drawbacks of various methods for processing different feedstock types have been discussed, and their main advantage and drawbacks are indicated, as well as their main disadvantages.
Abstract: General types of renewable carbon sources have been considered to be suitable for production of drop-in biofuels with minimum oxygen content, fully compatible with conventional fuels. The methods for processing different feedstock types have been discussed, their main advantages and drawbacks are indicated. Preparation of drop-in fuels from vegetable oils and waste of biodiesel production is possible in the framework of current methods without significant capital investments. Processing the pyrolysis products of lignocellulose biomass is fraught with a number of technical and technological problems, being currently at the research-and-development step.
TL;DR: In this article, new approaches to the formation of active, selective and stable Ni, Co, and Ni-Co catalysts for partial oxidation and dry reforming of methane into synthesis gas (a mixture of hydrogen and carbon monoxide) are considered.
Abstract: New approaches to the formation of active, selective, and stable Ni, Co, and Ni–Co catalysts for partial oxidation and dry reforming of methane into synthesis gas (a mixture of hydrogen and carbon monoxide) are considered.
TL;DR: In this paper, the performance of poly(ethylene terephthalate) track-etched membranes (PET TeM) was investigated in liquid-phase reduction of p-nitrophenol.
Abstract: Treatment conditions (oxidation, number of activation procedures) of a polymer template based on poly(ethylene terephthalate) track-etched membranes (PET TeMs) on the efficiency of the electroless deposition of copper, the structure of the synthesized copper nanotubes, and their catalytic activity in the liquid-phase reduction of p-nitrophenol are studied. It is shown that oxidative premodification contributes to an increase in the catalytic activity of the composite membrane by 20% compared with a sample synthesized in accordance with the standard procedure (etched PET TeM, single activation). In addition, it is found that the repeated implementation of the sensitization and activation stages leads to an increase in the reaction rate constant by 35 and 15% in the case of the etched and oxidized membranes, respectively. The properties of the catalysts in the temperature range of 16–35°C are studied; the activation energy Ea is calculated. The lowest Ea value is obtained for a sample synthesized in an unmodified matrix: electroless deposition into the polymer template without additional oxidative modification makes it possible to synthesize composite catalysts exhibiting relatively low catalytic activity; however, membranes of this type remain active in five test runs (p-nitrophenol conversion and reaction rate constant decrease by 26 and 44%, respectively).
TL;DR: In this article, the authors investigated the equilibrium adsorption of asphaltene onto several nanoparticles (NiO, MgO, Fe3O4) with different surface chemistry at various temperatures by UV-Vis spectroscopy.
Abstract: 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).
TL;DR: In this paper, the crystallization of an AlPO4-11 molecular sieve from various aluminum sources, namely, boehmite, pseudoboehmite, and aluminum isopropoxide, has been studied.
Abstract: The crystallization of an AlPO4-11 molecular sieve from various aluminum sources, namely, boehmite, pseudoboehmite, and aluminum isopropoxide, has been studied in this work. It has been found that the reactivity of the precursor affects the phase composition of the initial aluminophosphate gels and products of their subsequent crystallization as well as the morphology of the crystals of AlPO4-11 and characteristics of their porous structure.
TL;DR: In this article, the possibilities of reducing the viscosity of heavy fuel oil with an increased proportion of residual fractions through the use of nanomaterials, such as carbon nanotubes (CNTs) and dehydrated carbonate sludge, have been investigated.
Abstract: The possibilities of reducing the viscosity of heavy fuel oil with an increased proportion of residual fractions through the use of nanomaterials, such as carbon nanotubes (CNTs) and dehydrated carbonate sludge, have been investigated. The results of studying of rheological characteristics of fuel oil and composite fuel containing carbon nanotubes dispersed in an oil-soluble nonionic surfactant (M100 fuel oil + 0.0125 wt % CNT + 0.5 wt % Diproxamine) or dehydrated carbonate sludge (M100 fuel oil + 0.1 wt % carbonate sludge) are presented, as well as their heating value. The existence of a synergistic effect of the combined use of CNTs and carbonate sludge has been established. The possible mechanisms of change in the viscosity of the fuel are considered. It has been shown that carbon nanotubes together with dehydrated carbonate sludge can be most promising for use as heating oil additives, since they reduce fuel viscosity, improve combustion efficiency, and reduce the emission of hazardous gases.
TL;DR: In this article, the catalytic activity of copper nanotubes (NTs) in a PET matrix of track-etched membranes (TMs) in the flow mode and under stirring in the static mode is studied using the example of the classical p-nitrophenol (p-NP) reduction reaction.
Abstract: The catalytic properties of nanosized copper structures are the subject of many reports. In this study, the catalytic activity of copper nanotubes (NTs) in a PET matrix of track-etched membranes (TMs) in the flow mode and under stirring in the static mode is studied using the example of the classical p-nitrophenol (p-NP) reduction reaction. Composite TMs are prepared by the electroless template synthesis ; after 40 min of deposition, the inner diameter of the copper NTs is 295.4 nm, while the wall thickness does not exceed 47.5 ± 4 nm. The structure and composition of the synthesized composite membranes is studied by gas permeability, electron microscopy, energy dispersive analysis, and X-ray diffraction methods. It is shown that, in the flow screening mode, the composite catalyst provides a high p-NP reduction reaction rate; however, after the third test run, the reaction rate decreases by 97%; further, the composite is almost inert. In the static mode, at a relatively low reaction rate, the copper NT-based catalyst provides a high p-NP conversion and remains active for at least six consecutive test runs without any additional activation and regeneration. The results show that composite catalysts based on PET TMs and chemically deposited copper NTs are highly promising.
TL;DR: In this article, the feature of hydroformylation of model gas mixtures with different ethylene, hydrogen, and methane concentrations in the presence of rhodium catalysts has been studied.
Abstract: The feature of hydroformylation of model gas mixtures with different ethylene, hydrogen, and methane concentrations in the presence of rhodium catalysts have been studied. The effect of the initial pressure in the reactor and the reaction temperature on the reaction rate and selectivity has been determined. It has been shown that ethylene hydroformylation occurs with a high propanal selectivity (up to 99%), with the turnover frequency of the reaction reaching 9500 h–1. It has been proposed that various phosphine ligands should be used to implement alternative methods of separating the catalyst system from the reaction products.
TL;DR: In this article, a spiro diborate (SDB) was synthesized from glycerol monolaurate and boric acid, and was evaluated as viscosity-reducer and pour point depressor for crude oil.
Abstract: In this work, a spiro diborate (SDB), different from the traditional polymers, was synthesized from glycerol monolaurate and boric acid, and was evaluated as viscosity-reducer and pour point depressor for crude oil. The evaluation showed that this spiro compound can improve the flow properties of crude oil samples by reducing the viscosity of crude oil by 82.3% at most and depressing the pour point by 8.0°C. The role of SDB in limiting the degree of cocrystallization can be further confirmed by the average particle size and the particle morphology analysis of saturated hydrocarbons (HC) component illustrated from microscopic crystal morphology. So it can be concluded that the high content of saturated HC makes for the effective viscosity reduction.
TL;DR: In this article, a review summarizes information on the effect of wave effects on various processes in chemistry and petrochemistry and their classification by nature and by the physical bases of the processes taking place in this process is given.
Abstract: The review summarizes information on the effect of wave effects on various processes in chemistry and petrochemistry. Their classification by nature and by the physical bases of the processes taking place in this process is given. The main stages in the technology of oil refining (production, primary and deep oil refining, the use of fuels, environmental problems), in which wave processing plays a significant role, are considered. The questions of the mechanism of the effect of wave processes on oil systems are discussed.
TL;DR: In this paper, it has been shown that the nature of the support (MFI zeolite, aluminum-magnesium hydrotalcite, stabilized ceria, neodymia) has a significant effect on the stability of Ni and Ni-Co catalysts for partial oxidation of methane to synthesis gas.
Abstract: It has been shown that the nature of the support (MFI zeolite, aluminum–magnesium hydrotalcite, stabilized ceria, neodymia) has a significant effect on the stability of Ni and Ni–Co catalysts for partial oxidation of methane to synthesis gas and a less significant effect on the stability of the catalysts for dry reforming of methane to synthesis gas. It has been found that aluminum–magnesium hydrotalcite is the most advantageous support for nickel catalysts, because it reliably provides a high synthesis gas yield in partial oxidation and dry reforming of methane, whereas the MFI zeolite is a stable and selective support for Ni–Co catalysts for dry reforming of methane.
TL;DR: In this paper, the possibility of using the catalytic system based on formic acid and a transition metal salt in the presence of hydrogen peroxide for desulfurization of non-hydrotreated vacuum gas oil has been explored.
Abstract: The possibility of using of the catalytic system based on formic acid and a transition metal salt in the presence of hydrogen peroxide for desulfurization of nonhydrotreated vacuum gas oil has been explored. Conditions for effective oxidation of organic sulfur compounds and maximal extraction of oxidized compounds from the feedstock have been selected. It has been shown that the catalysts based on tungsten salts are the most effective those for oxidative desulfurization of heavy feedstock. Under optimum conditions, the degree of desulfurization of vacuum gas oil was 89%.
TL;DR: In this paper, the authors synthesize catalysts for the hydrogenation of bicyclic aromatic hydrocarbons of the diesel fraction using tetraphenylmethane molecules linked by methylene groups.
Abstract: Porous aromatic polymer materials based on tetraphenylmethane molecules linked by methylene groups have been synthesized. By impregnating these materials with nickel–tungsten and nickel–molybdenum thiosalts, catalysts for the hydrogenation of bicyclic aromatic hydrocarbons of the diesel fraction have been prepared. Nanoparticles of the active sulfide phase are formed in support pores during the reaction; it is assumed that after the formation of the nanoparticles, the support material will undergo partial degradation to rearrange the mesoporous structure into a macroporous structure providing the best diffusion of substrates to the surface of the sulfide nanoparticles. The synthesized catalysts have been tested in the hydrogenation of naphthalene and naphthalene derivatives at a hydrogen pressure of 5 MPa and a temperature of 380°C.
TL;DR: In this paper, the synthesis of two sets of zeolites of the MFI structural type with a crystal size of a few microns (1-5 μm) in the first set and 120-140 nm in the second set and different Si/Al molar ratios of 20-220 in each of the sets have been described.
Abstract: Results of a study on the synthesis of two sets of zeolites of the MFI structural type with a crystal size of a few microns (1–5 μm) in the first set and 120–140 nm in the second set and different Si/Al molar ratios of 20–220 in each of the sets have been described. The crystal sizes have been determined by dynamic light scattering and electron microscopy; the phase, textural, and acid properties of the samples have been studied by XRD, nitrogen sorption by the BET method, and ammonia TPD, respectively. The synthesized samples have been tested in the model n-hexane catalytic cracking reaction; the catalytic properties of the samples with respect to n-hexane conversion and the protolytic cracking, dehydrogenation, and hydride transfer reactions have been compared. It has been shown that a key role in the catalyst activity is played by the combination of the strong acid site concentration and the pore hierarchy factor (HF); the maximum conversion is observed at a strong acid site concentration of 0.2 mmol/g and HF = 0.26.
TL;DR: In this article, a review is devoted to the features of the synthesis of zeolites with nanosized crystals, which are of great interest for the processes of petroleum chemistry, gas chemistry, and organic synthesis.
Abstract: The review is devoted to the features of the synthesis of zeolites with nanosized crystals, which are of great interest for the processes of petroleum chemistry, gas chemistry, and organic synthesis. On the basis of analysis of published data, a classification is proposed for methods of directional control of the size of zeolite crystals. Methods for qualitative and quantitative controlling the composition of the reaction mixtures crystallized into nanoscale zeolites are considered in detail, as well as the effect of crystallization conditions on the change in the dispersity of zeolite crystals.
TL;DR: In this paper, a review of studies on the adsorptive immobilization of proteins on the surface of mesoporous molecular sieves (MMSes) and zeolites is presented.
Abstract: The review is aimed at analyzing and summarizing the published results of studies on the adsorptive immobilization of proteins on the surface of mesoporous molecular sieves (MMSes) and zeolites. The dependence of adsorption on the MMS pore size and the protein globule size is discussed. Particular attention is paid to the catalytic activity of the adsorption layers of enzymes on the surface of these adsorbents.
TL;DR: In this article, a three-stage process for the production of motor fuel (MT) components from lignocellulosic raw materials is described, and it has been found that water in an amount of up to 30% in ethanol solutions effectively inhibits the detrimental hydrocarbon cracking and catalyst coking processes.
Abstract: A three-stage process for the production of motor fuel (MT) components from lignocellulosic raw materials is described. In the first, pretreatment stage, lignocellulose is subjected to hydrolysis with cellulases followed by fermentation of the resulting sugars into ethanol; then, dilute ethanol solutions are concentrated by membrane vapor separation to obtain 70–80% solutions. At the third stage, aqueous ethanol solutions (water content 0–50%) in the presence of a Pd–Zn/Al2O3/MFI catalyst at 350°C and a space velocity of 0.6 h−1 are converted into alkanes, and С3–С8 olefins and С6–C12 aromatic compounds (MT components). It has been found that water in an amount of up to 30% in ethanol solutions effectively inhibits the detrimental hydrocarbon cracking and catalyst coking processes, thereby leading to a decrease in the formation of undesirable C1 and C2 products and an increase in the catalyst on-stream time to 100 h wherein the yield of the desired fraction is reduced only by 10–15%. The subsequent treatment of the catalyst surface with steam and hydrogen completely restores its catalytic activity.
TL;DR: In this article, a cobalt-molybdenum-containing sulfonium thiosalt is prepared; when decomposed in situ, it forms the catalyst active in hydrogenation and hydrodesulfurization.
Abstract: A cobalt-molybdenum-containing sulfonium thiosalt is prepared; when decomposed in situ, it forms the catalyst active in hydrogenation and hydrodesulfurization. The possibility of catalyst isolation and reuse in several hydrogenation cycles is shown. It is found that a lower selectivity for naphthalene hydrogenation products in catalyst recycling is associated with decrease in the dispersity of molybdenum sulfide nanoparticles and reduction in the degree of their promotion by cobalt atoms.
TL;DR: In this paper, the authors studied steam reforming of methane and its mixtures containing 5 and 10% propane in a membrane reactor with an industrial nickel catalyst NIAP-03-01 and a membrane in the form of 30-μm foil made of a Pd-Ru alloy.
Abstract: Steam reforming of methane and its mixtures containing 5 and 10% propane has been studied in a membrane reactor with an industrial nickel catalyst NIAP-03-01 and a membrane in the form of 30-μm foil made of a Pd–Ru alloy. At T = 823 K and a feed space velocity of 1800 h−1, the almost complete methane conversion is achieved, the selectivity for CO2 is more than 50%, and about 80% H2 is recovered from the reaction mixture. High conversion of CH4 in the membrane reactor under mild conditions allows the steam reforming of its mixtures with C2+ alkanes to be conducted in a single process, as shown by the example of model mixtures containing C3H8. Under selected conditions (T = 773 or 823 K, a feed space velocity of 1800 or 3600 h−1, a steam/methane ratio of 3 or 5, atmospheric pressure), almost complete C3H8 conversion is observed. The main “undesirable” reaction is methanation, leading to a decrease in the CH4 conversion. In the system under study, CH4 is formed with an increase in the feed space velocity. Methanation occurs as a result of C3H8 hydrocracking at a steam/feedstock ratio = 3 or the hydrogenation of CO2 as this ratio is increased to 5. The optimal conditions for steam reforming of methane mixtures containing up to 10% C3H8 are T = 823 K, steam/feedstock ratio = 5, and the feed space velocity of 1800 h−1. Under these conditions involving evacuation of the permeate, the feedstock conversion is complete, the selectivity for CO2 is 50%, and more than 70% H2 is recovered from the reaction mixture.
TL;DR: In this paper, the dealumination of nanosized zeolites Y with a crystal size of 50-1100 nm by treatment with ammonium hexafluorosilicate and steam heat treatment is discussed.
Abstract: The dealumination of nanosized zeolites is an important scientific problem, which should be solved to improve the activity of catalysts based on this zeolite in a broad range of heterogeneous catalytic reactions, particularly in commercial processes. However, the smaller the required size of the synthesized crystals, the lower the Si/Al ratio and the lower the degree of dealumination of this material can be achieved. In this study, the dealumination of zeolites Y with a crystal size of 50–1100 nm by treatment with ammonium hexafluorosilicate and steam heat treatment is discussed. It is shown that the dealumination with ammonium hexafluorosilicate is a “gentler” method in terms of structure preservation, whereas the dealumination by steam heat treatment provides a higher Si/Al ratio in the products; however, this method is inapplicable for crystals smaller than 500 nm, because it leads to the complete degradation of the structure. However, nanosized crystals can be dealuminated by treating with ammonium hexafluorosilicate. In this case, the degree of dealumination is close to 40%. A significant disadvantage of this method is the formation of a SiO2 film on the crystal surface; this feature substantially restricts the use of the ammonium hexafluorosilicate treatment in the synthesis of cracking catalysts.