Incipient Wetness Impregnation Research Articles

Regulating the Pt dispersion by increasing the specific surface area of Al2O3 support for perhydro-dibenzyltoluene catalytic dehydrogenation reaction

Perhydro-dibenzyltoluene (18H-DBT) have been paid more attention as liquid organic hydrogen carriers (LOHCs) because of its high hydrogen storage, easy transportation, low price and other advantages. The 18H-DBT dehydrogenation reaction rate is the key point of the hydrogen storage. In this work, the relationship between the Pt dispersion, the average coordinated number and the total catalyst activity for 18H-DBT dehydrogenation reaction was studied. Al2O3 with the large specific surface area was synthesized by the sol–gel method and Pt/Al2O3 catalysts were prepared by incipient wetness impregnation. Their catalytic performance was tested by 18H-DBT dehydrogenation reaction. It was found that the relationship between the Pt dispersion and the catalytic performance is a volcano curve. The optimal dispersion of Pt for dehydrogenation reaction is 11.16 %. That's because that there exists a balance between the Pt dispersion and the average coordinated number in order to obtain the best total catalyst activity. The experiments and characterization results show that the increasing of Pt dispersion will increase the active site number but the average coordinated number will decrease. DFT calculation results further confirm that the catalytic activity of the single active site would decline with the decreasing average coordinated number.

Novel Nanostructured Pd/Co-Alumina Materials for the Catalytic Oxidation of Atmospheric Pollutants.

Cobalt-doped alumina catalysts were prepared using different methods, either conventional wet impregnation (WI) and/or advanced spray impregnation (SI), and they were evaluated as novel oxidation catalysts for CO and MeOH oxidation. The spray impregnation technique was used with the aim of achieving the synthesis of core-shell catalytic nanostructures to secure the chemical/thermal stability of active sites on the catalyst carrier. The catalysts were further promoted with a low Pd content (0.5 wt.%) incorporated via either incipient wetness impregnation (DI) or spray impregnation. The results revealed the superior performance of the spray-impregnated catalysts (Co/γ-Al2O3-SI) for both reactions. The deposition of Co oxide on the outer surface of the alumina particle (SEM images) and the availability of the active Co phase resulted in the enhancement of the Co/γ-Al2O3 catalysts' oxidation activity. Pd incorporation increased the catalysts' reducibility (TPR-H2) and improved the catalysts' performance for both reactions. However, the Pd incorporation method affected the catalytic performance; with the SI method, the active phase of Co3O4 was probably covered with PdO and was not available for the oxidation reactions. On the contrary, the incorporation of Pd with the DI method resulted in a better dispersion of PdO all over the Co/Al catalyst surface, maintaining available Co active sites and a better Pd-Co interaction. MeOH desorption studies revealed the methanol oxidation mechanism: the Co/Al catalysts promoted the partial oxidation of MeOH to formaldehyde (HCHO) and dehydration to dimethyl ether (DME), while the Pd-based Co/Al catalysts enhanced the complete oxidation of methanol to CO2 and H2O.

Katalitička aktivnost uzoraka pseudobemita impregnisanih različitim koncentracijama kobalta u oksidativnoj degradaciji tartrazina u prisustvu Oksona

Pseudoboehmite was impregnated with cobalt using a incipient wetness impregnation method. Two different concentrations of cobalt were used for impregnation: 3 mas% and 6 mas% of Co2+ relative to the mass of pseudoboehmite. The obtained materials were calcined at 500 ºC. The synthesized catalysts were tested in the process of oxidative degradation of tartrazine dye in the presence of Oxon as a source of sulfate anion radicals. The influence of temperature on the dye degradation efficiency was investigated. It was observed that the degradation rate increases with the increasing of temperature. The experimentally obtained results were tested using the most common kinetic models and it was found that the reaction follows a pseudo-first order rate in all cases. It was also observed that with an increase in the cobalt content, the efficiency of the catalyst increases. In order to determine which reactive oxidative species is dominant in the investigated process, tertiary buthalnol and ethanol was added to the reaction system. According to the experimental results sulfate anion radicals were found to be the dominant reactive species.

Synergistic effect of K and Zn on Fe-based catalysts for efficient CO2 hydrogenation.

Excessive emission of CO2 into the atmosphere has severely impacted the global ecological environment. Converting CO2 into valuable chemicals and fuels is of great significance for sustainable development. However, low activity and undesirable selectivity often result from the inherent inertness of CO2. Herein, K- or/and Zn-modified Fe-based catalysts were prepared by an incipient-wetness impregnation method for CO2 hydrogenation via a cascade reaction. The results indicate that K species exist as K2O while Zn species exist as ZnFe2O4. In the CO2 hydrogenation pathway, K2O facilitates the adsorption of CO2 and restrains the adsorption of H2, accelerating the transformation of CO2 into C2-C4 olefins rather than paraffins while Zn species promote the dispersion of Fe species, leading to improved activity. Synergistically, a K- and Zn-modified Fe-based catalyst (2Zn-10K-Fe/Al) shows excellent catalytic CO2 hydrogenation activity, achieving a CO2 conversion of 77% which is 1.8 times that (42%) of the unmodified Fe-based catalyst (Fe/Al). Our catalyst also shows a significantly promoted selectivity to C2-C4 olefins of 17% in comparison with the Fe/Al catalyst (0%). It is envisioned that such a binary effect of elements might contribute to the low-cost and industrial production of Fe-based catalysts for selective CO2 conversion.

Oxidative Desulfurization of Simulated Diesel Fuel by Synthesized Tin Oxide Nano-Catalysts Support on Reduced Graphene Oxide

The modified Hummers method was applied to prepare graphene oxide (GO) from the graphite powder. Tin oxide nanoparticles with different loading (10-20 wt.%) supported on reduced graphene oxide were synthesized to evaluate the oxidative desulfurization efficiency. The catalyst was synthesized by the incipient wetness impregnation (IWI) technique. Different analysis methods like FT-IR, XRD, FESEM, AFM, and Brunauer-Emmett-Teller (BET) were utilized to characterize graphene oxide and catalysts. The XRD analysis showed that the average crystal size of graphene oxide was 6.05 nm. In addition, the FESEM results showed high metal oxide dispersions on the rGO. The EDX analysis shows the weight ratio of Sn is close to its theoretical weight. The reduction of metal oxide and (GO) has occurred in one step at temperatures of 400 °C for 2 hours. The performance of the catalysts for dibenzothiophene (DBT) removal using H2O2 as an oxidizing agent was determined under a range of different operating conditions. The results showed that the maximum desulfurization was 71.68% in the best conditions (DBT concentration = 385 ppm, time = 90 min, temperature = 60 oC, catalyst dosage = 0.04g, and amount of oxidant = 0.375 ml).

Effect of Ni/Al-MCM-41 Impregnation Method on Catalytic Deoxygenation of Reutealis Trisperma Oil

Deoxygenation of Reutealis trisperma oil into green diesel has been carried out using Ni/Al-MCM-41 catalyst. The Ni/Al-MCM-41 catalyst was prepared using the wetness impregnation and incipient wetness impregnation methods, hereinafter referred to as Ni/Al-MCM-41 (WI) and Ni/Al-MCM-41 (IWI). XRD and FTIR analysis shows a characteristic of amorphous phase for solid Al-MCM-41 catalyst. FTIR pyridine was used to assess the impact of the NiO impregnation technique on Lewis acid and Brønsted acidity. The acidity test showed that the Ni/Al-MCM-41 (WI) catalyst had the highest total acidity 0,227 mmol/g. The catalytic activity of Ni/Al-MCM-41 catalyst was examined in deoxygenation reaction of Reutealis trisperma oil under inert conditions for 4 hours. In comparison to Ni/Al-MCM-41(IWI) and Al-MCM-41 catalysts, the Ni/Al-MCM-41(WI) catalyst produced better results in the deoxygenation reaction of Reutealis trisperma oil with a selectivity of hydrocarbon compounds (C11-18) of 100% and a degree of deoxygenation of 92.77%.

Effects of molybdenum addition to activated carbon supported Ni‐based catalysts for CO2 methanation

AbstractRecently, CO2 methanation has become a technique that aims to reduce anthropogenic CO2 emissions by converting CO2 captured from stationary and mobile sources and H2 produced from renewable sources into CH4. Due to their excellent performance‐to‐cost ratio, Ni‐based catalysts were frequently used in such conversions. The main drawbacks, however, are that Ni has the propensity to aggregate and deposit carbon during the high‐temperature reaction. These issues can be partially resolved by including a support (e.g., MOF, zeolite, activated carbon, etc.) and a second transition metal (e.g., Mo, Co, or Fe) in Ni‐based catalysts. Therefore, the activity of Ni‐based catalysts at low temperatures needs to be improved. In this study, a series of mesoporous activated carbon (AC) supported bimetallic Ni–Mo catalysts (Ni–xMo/AC, Ni = 13 wt.%, x = 5, 7, 9, 11 wt.%) were synthesized using the incipient wetness impregnation method. The effect of Mo content on the catalyst's activity was examined in a fixed‐bed reactor. At 250–650°C, 1‐atmosphere pressure, gas hourly space velocity (GHSV): 1200 mL h−1 g−1, and H2/CO2 ratio: 4:1, the catalytic efficiency of these catalysts was examined. The catalysts were analyzed using transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), X‐ray powder diffraction (XRD), N2‐physisorption, and scanning electron microscopy/energy dispersive X‐ray spectroscopy (SEM‐EDX). Ni–7%Mo/AC catalyst showed the lowest carbon deposition rate, superior stability, and the best activity. The addition of Mo can improve the heat resistance of the Ni/AC catalyst and the interaction between the metal nickel and the support, which prevents the sintering of the catalyst. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Scalable Synthesis of Stable Electrocatalyst for Oxygen Reduction Reaction

Carbon-based materials have been widely recognized as support material of choice for the oxygen reduction reaction due to their intriguing properties, such as high electrical conductivity, structural flexibility, and low cost. Platinum and its alloys supported on carbon are currently considered the benchmark catalysts for the oxygen reduction reaction (ORR) in Proton Exchange Membrane Fuel Cells (PEMFCs). Confining platinum within the pore system of mesoporous carbon prepared by hard-templating has proven to be an effective way to mitigate catalyst degradation in PEMFCs.[1] However, the challenge of template removal and the limited yield have hindered its practical application in industry. As a remedy, we establish a simple synthesis of carbon gels through sol-gel polymerization of resorcinol (R) and formaldehyde (F), ultimately resulting in graphitic mesoporous carbons.The synthesis process involves mixing resorcinol and formaldehyde in the presence of a basic catalyst, followed by heating for a certain period of time to obtain crosslinked gels.[2] Specific metal salts can be incorporated into the reaction to synthesize mesoporous and highly graphitic carbon spheres (GRF-Sphere) in a straightforward manner, without the need for hydrothermal steps, solvent exchanges, supercritical drying, or post-activation techniques. While conventional carbonized RF spheres are typically non-graphitic and microporous (Fig. 1.), modification of the synthesis route allows for the production of mesoporous, highly graphitic carbon spheres (GRF-Sphere) by taking advantage of the porogenic and graphitization effect of Fe(acac)2. Platinum nanoparticles with an average size of ca. 3 nm were deposited into the pores of GRF-spheres by incipient wetness impregnation followed by annealing at 750 °C. The specific activity of the Pt/GRF-Sphere catalyst for the ORR was found to be greater than 0.45 mA cm-2 Pt at 0.9 V vs. RHE, which in comparison with the literature indicates high catalytic activity.[3] The confinement of the active phase within the pores of the GRF-Spheres contributed to enhancing the stability of the catalyst, as confirmed by an accelerated stress test performed within the typical operating range of a PEMFC (0.6 - 1.0 VRHE). The Pt/GRF-Sphere was found to retain a significantly higher proportion of active surface area when compared to a reference Pt/Vulcan catalyst with similar platinum particle size (Fig. 1.).Furthermore, increasing the concentrations of resorcinol and formaldehyde by 25-fold resulted in the synthesis of a mesoporous and highly graphitic gel, namely GRF-Gel, at a substantial volume yield of70 g L-1, which underlines the potential for this process to be scaled up for industrial application. The ORR activity and stability of GRF-Gel in RDE are currently being investigated. Moreover, the electrochemical performance of this material will be evaluated in a single-cell PEMFC in collaboration with the group of Prof. Hubert Gasteiger (TU Munich).Overall, this research provides a promising and straightforward approach to synthesize highly graphitic mesoporous carbon materials using iron acetylacetonate as a porogen and graphitization catalyst. The method is based on the established preparation of RF-gels but includes iron salts. We have demonstrated that Pt/GRF-Sphere, which is produced by depositing Pt nanoparticles into the pore system of the GRF-Sphere, exhibits high activity and stability for the ORR. Given the simplicity and scalability of our synthesis procedure and the tailored morphology of these carbon materials, we believe that Pt/GRF-Sphere and Pt/GRF-Gel have great potential for industrial applications. Acknowledgement: We acknowledge the financial support from the German Federal Ministry for Economic Affairs and Energy (BMWi) in the framework of POREForm (project number 03ETB027F).

CoPMoV Sulfide Catalysts Supported on Natural Halloysite Nanotubes in Hydrotreating of Dibenzothiophene and Naphthalene

Mixed sulfided CoMo catalysts supported on γ-Al2O3 and halloysite nanotubes (HNTs) were synthesized by incipient wetness impregnation with salt solutions of Keggin-type phosphorus- and vanadium-containing heteropolyacids. The synthesized materials were characterized by low-temperature nitrogen adsorption, energy dispersive X-ray fluorescence analysis, temperature-programmed reduction (both for the oxide and sulfide catalysts), and Raman spectroscopy, and were tested in hydrogenation of naphthalene and hydrodesulfurization of dibenzothiophene. The HNT-supported catalyst exhibited a greater activity in these reactions.

Non‐oxidative Methane Activation over Molybdenum and Tungsten Nitride Catalysts

AbstractIn this study, molybdenum (Mo), tungsten (W), and mixed metal oxide and ‐nitride catalysts are synthesized via incipient wetness impregnation on silica support (SBA‐15) with a total target metal loading of 4 wt %. The effect of the Mo : W ratio on the non‐oxidative methane conversion, product selectivity, and coke formation is evaluated. The reduced Mo/SBA‐15 and MoW/SBA‐15 catalysts show higher CH4 conversion activity to benzene (selectivity of ~75.5 %) than for ethylene (selectivity of ~9.5 %) with a rather fast coke formation rate of 19–24 mgCoke gCat−1 h−1 without a clear influence of the Mo : W ratio. In contrast, the metal nitrides have a much smaller coke formation rate. The smallest rate of 0.45 mgCoke gCat−1 h−1 is achieved for the WN/SBA‐15 sample, which increases with the molybdenum content to 4.7 and 8.6 mgCoke gCat−1 h−1 for the MoWN(5 : 1) and MoN/SBA‐15 catalysts, respectively. There seems to be a yet unknown but negative correlation between the coke formation rate and the number of silanamine functional groups formed during the catalyst nitridation (Si−OH→≡Si−NH2→≡Si−NH−Si≡). The C2H4 selectivity is significantly increased with the relative amount of tungsten, with the highest C2H4 selectivity of 63 % for mixed‐metal nitride catalyst containing Mo : W ratio of 1 : 5. While the Mo/SBA‐15 the MoN/SBA‐15 achieve a C2H4 selectivity of less than 10 %.

Synergistic Ti-Fe Oxides on Fishbone-Derived Carbon Sulfonate: Enhanced Styrene Oxidation Catalysis

Fishbone-derived carbon sulfonate, modified through incipient wetness impregnation with titanium tetraisopropoxide and iron nitrate salts, displays catalytic activity in the oxidation of styrene with hydrogen peroxide (H2O2) as an oxidant. This was done to develop a cost-effective, non-toxic, and environmentally friendly bimetallic oxide catalyst, incorporating titanium and iron oxides on mesoporous-derived carbon fishbone to enhance styrene conversion and benzaldehyde selectivity in styrene oxidation using aqueous H2O2. The catalyst, featuring a combination of titanium and iron oxides on the surface of the fishbone-derived carbon sulfonate, demonstrates higher catalytic activity than single oxide catalysts, such as titanium or iron oxides alone. Factors influencing the catalyst's performance are investigated by using FTIR, XRD, XRF, SEM, and BET surface area. The results reveal that the presence of both titanium and iron oxides on the surface of the fishbone-derived carbon sulfonate and the catalyst's surface area creates a synergistic effect, the primary factors affecting its catalytic activity in styrene oxidation using H2O2 as an oxidant.

Cu-promoted Ni-LaCeOx/SBA-15 catalysts for ethanol steam reforming

Hydrogen is a globally recognized high-energy, clean, and ecofriendly fuel that is currently produced by means of electrocatalysis, biomass conversion, coal gasification, and thermal decomposition of hydrocarbons, with the steam reforming showing high potential. The present work is focused on Cu-promoted SBA-15-supported Ni-LaCeOx catalysts for ethanol steam reforming (ESR). The catalysts were prepared by incipient wetness impregnation and characterized by XRF, N2 adsorption-desorption, IR spectroscopy, SAXS, XRD, H2-TPR, Raman, and STA methods. The support features caused by the distribution of LaCeOx NPs and Cu promoter in proper ratios affect the conditions of formation of active dispersed Ni species to determine the catalyst performance and its reducibility. At 800 оС, the NiСu-LaCeOx/SBA-15 (1:1) catalyst demonstrates a 100 % ethanol conversion and 55 % hydrogen yield. Thus, the role of the Cu-containing promoter comprises both a significant decrease of carbon deposits on the catalyst surface and redirecting of the intermediate interactions towards the formation of the desired gaseous products.

Carbon dioxide hydrogenation to value-added products using Cu-based catalytic materials

In this work, we report on the synthesis and evaluation of catalytic materials composed of copper/calcium oxide/alumina (Cu/CaO/Al2O3) for carbon dioxide conversion to value-added products. Catalytic materials were synthesized using sequential incipient wetness impregnation method. Synthesized materials with different compositions of copper and adsorbent were tested in a high-pressure packed bed reactor under a pressure P =60 bars, temperature T=300 °C, and hydrogen to carbon dioxide ratio (H2/CO2 = 3) to determine their performances and catalytic activities. The results of the activity revealed that CaO-based catalysts were very active in converting CO2 to methanol and carbon monoxide. Catalyst containing 30%Cu10%CaO achieved the highest CO2 conversion of 16.5% and a maximum methanol selectivity of 17.8%, while the lowest selectivity towards carbon monoxide (CO) were obtained using 20%Cu-containing catalyst. Reducing CaO content from 10wt% to 5wt% boosted the CO2 conversion to 18% with higher selectivity towards CO compared to the catalyst containing 10%CaO.

Broadening active temperature window for NH3-SCR on tungsten-promoted MnCeOx nanorod catalysts

xW/MnCe nanorod catalysts with various tungsten contents were synthesised using the incipient wetness impregnation method for selective catalytic reduction (SCR) of nitrogen oxides with NH3 (i.e. NH3-SCR reaction). Tungsten addition considerably widened the active temperature window and enhanced the SO2/H2O tolerance of the catalysts. The optimum catalytic performance was achieved when the tungsten content was 15 wt% with NOx conversion being ≥ 80% in the range of 175–450 °C. The MnCe nanorods approximately retained their morphology after tungsten loading. Microcrystalline WO3 formed when the W content was 15%, resulting in increments in the amount of Ce3+ and Mn4+, which is in favour of the NH3-SCR reaction on the catalyst surface. Moreover, the broad active temperature windows of the tungsten-modified MnCe nanorod catalysts were related to the balance between the redox and acidic properties. Tungsten addition enhanced the acidity of the MnCe catalyst while suppressing its reducibility. Both the Brønsted and Lewis acid sites are active, and the formation of reactive bridging nitrate species promote the performance of 15 W/MnCe catalyst. Overall, this study provided an easy method of adjusting the active temperature window of Mn–Ce nanorod catalysts through W modification.

Tailoring optical and dielectric properties of TiO2 through mono- and co-doping with Ag and Sr

In this study, we applied a direct and incipient wetness impregnation technique to synthesize titanium dioxide (TiO2) doped with silver (Ag), strontium (Sr), and a combination of the two elements. The purpose was to further our understanding of doped TiO2 materials. The results of scanning electron microscopy (SEM) analysis showed that the agglomerated particles of the doped composites had smaller sizes than those of pure TiO2. The incorporation of Ag–Sr bimetallic doping led to a more pronounced reduction in the particle size. The SEM images revealed no significant morphological alterations in the TiO2, Ag/TiO2, Sr/TiO2, and Ag–Sr/TiO2 composites. We also examined the dielectric characteristics of composites within a range of temperature of 25 °C–120 °C and a range of frequency of 100 Hz to 0.3 MHz. The electrical conductivity and dielectric permittivity of TiO2 were enhanced as a result of doping. The optical characteristics of the composites indicated that the introduction of Ag, Sr, and Ag–Sr into TiO2 led to an increase in both their refractive index and Urbach energy. This led in turn to a progressive reduction in the energy band gap (Eg) from the Ag-doped samples to the Ag–Sr-doped samples, with the Sr-doped samples exhibiting an intermediate reduction in Eg. The findings of this study indicate that the introduction of Ag, Sr, and Ag–Sr into TiO2 enhanced its refractive index. Notably, the Ag–Sr/TiO2 composite exhibited the most significant increase in the refractive index of all the composites considered. This phenomenon can be attributed to the increased level of polarization and crystallinity of the compound. By contrast, the incorporation of Ag, Sr, and Ag–Sr into composite materials composed of TiO2 led to a reduction in the values of Eg, where this renders these materials suitable for various optical applications.

Carbon dioxide reforming of methane over modified iron-cobalt alumina catalyst: Role of promoter

BackgroundCobalt-based catalysts are widely employed in methane dry reforming but tend to deactivate quickly due to coke deposits and metal sintering. To enhance the performance, iron, a cost-effective promoter, is added, improving cobalt's metal dispersibility, reducibility, and basicity on the support. This addition accelerates carbon gasification, effectively inhibiting coke deposition. MethodsA series of iron-doped cobalt alumina MFe-5Co/Al2O3 (M= 0, 0.4, 0.8, 1, 2 wt.%) were prepared via simple incipient-wetness impregnation. The catalysts were thoroughly characterized via modern techniques including BET, XRD, H2-TPR, CO2-TPD. Significant findingsThe addition of iron had a minimal impact on the properties of γ-Al2O3, but it significantly affected the dispersibility of cobalt. At an optimal dosage of 0.8 wt.%, there was a notable decrease of 29.44% in Co3O4 particle size. However, excessive iron loading induced agglomeration of Co3O4, which was reversible. The presence of iron also resulted in a decrease in the reduction temperature of Co3O4. The material's basicity was primarily influenced by the loading of iron, reaching its highest value of 705.7 μmol CO2 g−1 in the 2Fe-5Co/Al2O3. The correlation between catalytic activity and the physicochemical properties of the material was established. The 0.8Fe-5Co/Al2O3 sample exhibited excellent performance due to the favorable dispersibility of cobalt, its reducibility, and its affordable basicity.

A Fluidizable Catalyst for N-Butane Oxidative Dehydrogenation under Oxygen-Free Reaction Conditions

This study evaluates the effectiveness of fluidizable VOx/MgO-γAl2O3 catalysts for C4-olefin production via n-butane oxidative dehydrogenation (BODH). Catalysts were prepared via vacuum incipient wetness impregnation and then characterized by employing several techniques such as BET (Brunauer–Emmett–Teller) method, XRD (X-ray diffraction), LRS (laser Raman spectroscopy), XPS (X-ray photoelectron spectroscopy), TPR/TPO (temperature-programmed reduction/temperature-programmed oxidation), NH3-TPD (temperature-programmed desorption), NH3 -desorption kinetics and pyridine-FTIR. The BET analysis showed the prepared catalysts’ mesoporous structure and high surface areas. The XRD, LRS and XPS established the desirable presence of amorphous VOx phases. The TPR/TPO analyses corroborated catalyst stability over repeated reduction and oxidation cycles. The NH3-TPD and NH3 desorption kinetics showed that the catalysts had dominant moderate acidities and weak metal-support interactions. In addition, Pyridine-FTIR showed the critical influence of Lewis acidity. The VOx/MgO-γAl2O3 catalysts were evaluated for BODH using a fluidized CREC Riser Simulator, operated under gas-phase oxygen-free conditions, at 5 to 20 s reaction times, and at 450 °C to 600 °C temperatures. The developed VOx/MgO-γAl2O3 catalysts demonstrated performance stability throughout multiple injections of butane feed. Catalyst regeneration was also conducted after six consecutive BODH runs, and the coke formed was measured using TOC (Total Organic Carbon). Regarding the various BODH catalyst prepared, the 5 wt% V-doped MgO-γAl2O3 yielded in a fluidized CREC Riser Simulator the highest selectivity for C4-olefins, ranging from 82% to 86%, alongside a butane conversion rate of 24% to 27%, at 500 °C and at a 10 s reaction time.

The influence of chemical composition and preparation procedure on CO2 capture performance of NaNO3 /MgO-based sorbents

MgO based sorbents modified by 5–50 mol.% NaNO3 have been prepared by various methods and investigated in detail. It has been showed that optimal synthesis method is incipient wetness impregnation of MgO precursor with sodium nitrate water solution. The highest sorption capacity of 6.5 mmol CO2 g–1 sorb after 1 hour of sorption from the gas mixture with 50 vol.% CO2 at 320 °C was achieved using the MgO modified by 10 mol.% NaNO3. Sorption capacity for MgO modified by 10 mol.% NaNO3 during 10 consecutive sorption-desorption cycles is approximately 4.5–5.5 mmol CO2 g–1 sorb. The duration of the sorption stage is 30 min, the CO2 content in the feed gas is 50 vol.% and sorption-regeneration temperature is 300–350 °C respectively. It has been showed that increasing the sorption pressure to 10 bar allows reducing sorption temperature from 320 °C to 220–260 °C. The sorption capacity is reached up to 4.0 mmol CO2 g–1 sorb at 25 vol.% CO2 that is twice higher than that at 1 bar. It has been demonstrated that steam and hydrogen treatment before sorption doesn’t lead to a significant change in the sorption properties and phase composition of NaNO3 modified MgO-based sorbent.

Palladium-Containing Catalysts Based on Functionalized CNFs for the Dehydrogenation of Methylcyclohexane

The activity of palladium-containing catalysts based on functionalized carbon nanofibers prepared by an incipient wetness impregnation method in the dehydrogenation reaction of methylcyclohexane was investigated. Methylcyclohexane is considered as one of the most promising liquid hydrogen carriers. The dependence of the catalytic characteristics of the samples on the functionalization conditions of carbon nanofibers has been studied. By temperature-programmed desorption, it was shown that an increase in the treatment time of carbon nanofibers in concentrated nitric acid from 1 to 3 h increases the number of hydroxyl groups on their surface, and treatment for 6 h contributes to a rise in the concentration of carboxyl groups and their derivatives (esters and anhydrides). Additional calcination of the functionalized nanofibers in an inert atmosphere at 530°C yielded a sample containing predominantly hydroxyl groups. The presence of hydroxyl groups on the surface of the carbon material has a positive effect on the performance of the catalysts, while the presence of carboxyl groups leads to a decrease in the yield of toluene. It is assumed that the observed differences in catalyst activity are due to differences in dispersion and localization of palladium particles.

SELECTIVE HYDROGENATION OF CO IN THE PRESENCE OF NICKEL-CONTAINING CARBON CATALYSTS

Methanation process, or selective hydrogenation of carbon oxides, is described. The chemical foundations of the process and the features of the formation of reaction products are considered, depending on the catalyst used. The advantages of catalytic systems based on carbon materials and disadvantages of the catalysts on oxide substrates for the production of synthetic methane are evaluated. Nickel-containing carbon catalysts based on birch activated carbon and microcellulose were obtained by incipient wetness impregnation and hydrothermal synthesis, and proposed for the selective hydrogenation of carbon monoxide. The synthesized samples were studied by optical emission spectroscopy with inductively coupled plasma, low-temperature nitrogen adsorption, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, thermogravimetric analysis. The influence of the substrate and the method of catalyst synthesis on CO conversion and methane yield from the selective hydrogenation of CO was studied, and the optimal size of NiO and Ni(OH)2 crystallites, the precursors or the active phase, was determined. It is shown that the best carbon monoxide conversion and methane yield from methanation reaction are achieved in the presence of nickel-containing microcellulose-based carbon sample obtained by hydrothermal synthesis.