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Two series of MCM-36 zeolites intercalated with various pillars and modified with iron were synthesized, analyzed with respect to their physicochemical properties, and tested as catalysts for the NH3-SCR process. It was found that the characteristic MWW morphology of MCM-36 can be obtained successfully using silica, alumina, and iron oxide as pillars. Additionally, one-pot synthesis of the material with iron resulted in the incorporation of monomeric Fe3+ species into the framework positions. The results of catalytic tests revealed that the one-pot synthesized sample intercalated with silica and alumina was the most efficient catalyst of NO reduction, exhibiting ca. 100% activity at 250 °C. The outstanding performance of the material was attributed to the abundance of Lewis acid sites and the beneficial influence of alumina on the distribution of iron species in the zeolite. In contrast, the active centers originating from the Fe2O3 pillars improved the NO conversion in the high-temperature range. Nevertheless, the aggregated particles of the metal oxide limited the access of the reacting molecules to the inner structure of the catalyst, which affected the overall activity and promoted the formation of N2O above 300 °C.

The present research focuses on a Ni-Mg-Al hydrotalcite-derived catalyst promoted with Cu. Catalysts were prepared by the co-precipitation method at constant pH and were subsequently characterized via XRD, H2-TPR, CO2-TPD, TGA, XAS, TEM, low-temperature nitrogen sorption and tested for CO2 hydrogenation to methane. The methanation reaction was carried out at GHSV of 12,000 ml∙g-1 h-1 and high selectivity (above 98%) and activity in CO2 conversion (up to 86%) were observed at 350℃ on the HTNi15Cu1 sample containing 1.3 wt% Cu. The influence of Cu promotion was especially visible at low temperatures (250-300℃) where significant CO2 conversion is observed when compared to the non-promoted sample. The sample with the highest copper content was less selective for methane formation but promoted the reverse water-gas shift reaction. Also, its activity was the worst in the examined series, indicating that high Cu concentrations are not suited for CO2 methanation. It was likewise observed that with an increase in Cu content, Ni-Cu solid solution is formed. Later, during the methanation reaction, Ni-Cu alloy undergoes redispersion due to the atomic erosion effect, forming well-dispersed nickel nano-crystallites.

Selective catalytic reduction with ammonia (NH3-SCR) is very efficient DeNOx technique. According to some problems with the commercial catalyst, novel one should be prepared. Hydrotalcites are potential precursors of the new catalysts of NH3-SCR. In this paper, several attempts to apply these materials in NH3-SCR are presented.

The catalytic performance of Fe-catalysts in selective catalytic reduction of nitrogen oxides with ammonia (NH-SCR) strongly depends on the nature of iron sites. Therefore, we aimed to prepare and investigate the catalytic potential of Fe-MCM-22 with various Si/Fe molar ratios in NH-SCR. The samples were prepared by the one-pot synthesis method to provide high dispersion of iron and reduce the number of synthesis steps. We have found that the sample with the lowest concentration of Fe exhibited the highest catalytic activity of ca. 100% at 175 °C, due to the abundance of well-dispersed isolated iron species. The decrease of Si/Fe limited the formation of microporous structure and resulted in partial amorphization, formation of iron oxide clusters, and emission of NO during the catalytic reaction. However, an optimal concentration of FeO oligomers contributed to the decomposition of nitrous oxide within 250–400 °C. Moreover, the acidic character of the catalysts was not a key factor determining the high conversion of NO. Additionally, we conducted NH-SCR catalytic tests over the samples after poisoning with sulfur dioxide (SO). We observed that SO affected the catalytic performance mainly in the low-temperature region, due to the deposition of thermally unstable ammonium sulfates., Agnieszka Szymaszek-Wawryca gratefully acknowledges financial support from the National Science Centre Grant Preludium 19 (no. 2020/37/N/ST5/00186). Urbano Díaz acknowledges the support from Government of Spain through the project PID2020-112590GB-C21/AEI/10.13039/501100011033. The research results presented in this paper by Monika Motak have been developed with the use of equipment financed from the funds of the “Excellence Initiative—Research University” program at AGH University of Science and Technology. Bogdan Samojeden’s research was supported by the program “Excellence initiative—research university” for the AGH University of Science and Technology.

In order to produce valuable syngas, industrial processes of dry reforming of methane and steam reforming of methane must be further developed. This paper is focused on reviewing recently examined catalysts, supporting the mentioned technologies. In both processes the most popular active material choice is usually nickel, due to its good availability. On the other hand, noble metals, such as ruthenium, rhodium or platinum, provide better performance, however the solution is not cost-effective. Materials used as a support influence the catalytic activity. Oxides with basic properties, such as MgO, Al2O3, CeO2, are frequently used as carriers. One of the most promising materials for reforming of methane technologies are hydrotalcites, due to adjustable composition, acid-base properties and possibility of incorporation of various metals and complexes.

Natural zeolite of the heulandite-type framework was modified with iron and tested as a catalyst for the selective catalytic reduction of nitrogen oxides with ammonia (NH3-SCR) in the temperature range of 150–450 °C. The catalyst was prepared at a laboratory scale in a powder form and then the series of experiments of its shaping into tablets was conducted. Physicochemical studies of the catalyst (N2 sorption at −196 °C, FT-IR, XRD, UV-vis) were performed to determine the textural and structural properties and identify the surface functional groups, the crystalline structure of the catalysts and the form and aggregation of the active phase. The activity tests over the shaped catalyst were performed industry-reflecting conditions, using tail gases from the pilot nitric acid plant. The influence of a temperature, catalyst load, and the amount of reducing agent (ammonia) on the NOx reduction process were investigated. The results of catalytic tests that were performed on model gas mixture showed that non-modified clinoptilolite exhibited around 58% conversion of NO at 450 °C. The temperature window of the shaped catalyst shifted to a higher temperature range in comparison to the powder sample. The catalytic performance of the shaped Fe-clinoptilolite in the industry-reflecting conditions was satisfactory, especially at 450 °C. Additionally, it was observed that the ratio of N2O concentration downstream and upstream of the catalytic bed was below 1, which indicated that the catalyst exhibited activity in both DeNOx and DeN2O process.

A series of cobalt-promoted Ni-Mg-Al hydrotalcite-derived catalysts were tested towards CO2 methanation reaction. The best among examined catalysts was the one with 1 wt% of cobalt in fresh hydrotalcite, obtaining 77% of CO2 conversion and 99% of CH4 selectivity at 300 °C. Above that temperature, the catalyst was working with-near-equilibrium parameters. It was also stable for up to 24 h on stream. Other cobalt-containing samples were likewise very active and selective during the time on stream. Due to the use of a low amount of cobalt (0.5–4 wt%) the Co-Ni alloy was not the subject of research – both materials formed probably solid solution of cobalt in the nickel matrix. Although the behavior of cobalt as a textural and electronic promoter was confirmed. Co was found to improve reducibility of nickel species, hydrogen uptake, and the acidic/basic properties by increasing the number of medium strength and strong basic sites. Tendency to sintering of nickel crystallites on cobalt-promoted catalysts was not confirmed in this study, however, with increased content of Co, bigger metal crystallites were formed under the reduction conditions.

Nitrogen dioxide is one of the most dangerous air pollutants, because its high concentration in air can be directly harmful to human health. It is also responsible for photochemical smog and acid rains. One of the most commonly used techniques to tackle this problem in large combustion plants is selective catalytic reduction (SCR). Commercial SCR installations are often equipped with a V2O5&minus, WO3/TiO2 catalyst. In power plants which utilize a solid fuel boiler, catalysts are exposed to unfavorable conditions. In the paper, factors responsible for deactivation of such a catalyst are comprehensively reviewed where different types of deactivation mechanism, like mechanical, chemical or thermal mechanisms, are separately described. The paper presents the impact of sulfur trioxide and ammonia slip on the catalyst deactivation as well as the problem of ammonium bisulfate formation. The latter is one of the crucial factors influencing the loss of catalytic activity. The majority of issues with fast catalyst deactivation occur when the catalyst work in off-design conditions, in particular in too high or too low temperatures.

A novel approach was used as support for synthesis of fly ash derived catalyst from waste fly ashes from the energy sector was used as support in the preparation of Ni-catalysts for CO2 methanation. The catalysts were characterized by XRD, H2 -TPR, CO2 -TPD and N2 low-temperature nitrogen sorption. As a result of application of new approach using a ball-mill mechanical energy, carbon dioxide conversion to methane of 58% was obtained at 350 °C. The conversion long with economical aspects of catalyst preparation, including waste material reuse, leads to highly promising results. The results indicate that the catalyst for the methanation process can be easily obtained by the mechanical activation of waste from the energy sector. The chemical modification is more complicated and does not give significantly better results. This approach to waste transformation is innovative, ecological, and economical. It meets the assumptions of the circular economy concept and allows to reuse of waste materials.

Insertion of transition metal species into crystalline alumina at low temperatures is proposed to achieve the dispersion of these species at atomic level paired with exceptional textural properties. Precisely, MeAl

Cenospheres from coal fly ashes were used as support in the preparation of Ni&ndash, Mg catalysts for dry reforming of methane. These materials were characterized by means of XRD, H2-temperature-programmed reduction (H2-TPR), CO2-temperature-programmed desorption (CO2-TPD), and low-temperature nitrogen sorption techniques. The cenosphere-supported catalysts showed relatively high activity and good stability in the dry reforming of methane (DRM) at 700 &deg, C. The catalytic performance of modified cenospheres was found to depend on both Ni and Mg content. The highest activity at 750 &deg, C and 1 atm was observed for the catalyst containing 30 wt % Mg and 10, 20, and 30 wt % Ni, yielding to CO2 and CH4 conversions of around 95%.

The adsorption of ketoprofen, naproxen, and diclofenac (non-steroidal anti-inflammatory drugs, NSAIDs) on halloysite/carbon nanocomposites and non-modified halloysite were investigated in this work. Halloysite/carbon nanocomposites were obtained through liquid phase impregnation and carbonization using halloysite as the template and saccharose as the carbon precursor. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FT-IR), and low-temperature nitrogen adsorption method were employed to study the morphological and structural changes of the halloysite/carbon nanocomposites. The effects of contact time, initial concentration of adsorbates, pH of solution, and mass of adsorbent on the adsorption were studied. Adsorption mechanism was found to fit pseudo-second-order and intra-particle diffusion models. The obtained experimental adsorption data were well represented by the Langmuir multi-center adsorption model. Adsorption ability of halloysite/carbon nanocomposites was much higher for all the studied NSAIDs in comparison to non-modified halloysite. Optimized chemical structures of ketoprofen, naproxen, and diclofenac obtained by Density Functional Theory (DFT) calculation showed that charge distributions of these adsorbate molecules and their ions can be helpful to explain the details of adsorption mechanism of NSAIDs on halloysite/carbon nanocomposites.

Montmorillonite intercalated with mixed alumina–iron (III) oxide pillars and promoted with hexamminecobalt (III) chloride was studied in selective catalytic reduction of NO with NH3. Pillaring process extended the interlayer spacing by 0.236 nm and increased specific surface area (SSABET) from 33 m2 up to 299 m2. Interlayer space width did not change after calcination process, but high temperature could cause decomposition of hexamminecobalt (III) – [Co(NH3)6]3+, possibly to Co2+. Promotion of hexamminecobalt (III) chloride to pillared clay did not significantly change SSABET. The intercalation process influenced positively selective catalytic reduction activity, but very high formation of N2O was observed. Pillared clay, promoted with [Co(NH3)6]3+, showed higher selective catalytic reduction activity and much lower N2O formation than unpromoted, pillared sample. Clay with interlayer cations exchanged for [Co(NH3)6]3+, without pillaring, showed no selective catalytic reduction activity, but still produced...

Activated carbons modified with ammonia were used as sorbents of SO2. The SO2 uptake was dependent on both texture and type of surface groups introduced onto the studied materials. The most importa...

New catalysts based on activated carbon, which may be used for tail-end SCR (Selective catalytic reduction), were studied. They were modified by pre-oxidation, introduction of N-surface groups via impregnation with an aqueous solution of urea and subsequent impregnation with Fe(NO3)3 or Mn(NO3)2. The catalysts modified with Fe and Mn showed similar NO conversion, but the former was characterized by better selectivity and stability. The H2O presence in the SCR mixture led to the decrease of NO conversion at low and medium temperature region, which was totally reversible after the removal of water. However, water positively influenced selectivity.

Cenospheres were modified with iron, manganese and/or copper ions by the hydrotalcite method. The obtained catalysts were characterized by FTIR, XRD and low-temperature nitrogen sorption. The best catalyst at low temperature (200 °C) was CBFe-Mn while at the highest measured temperature of 500 °C both CBFe-Mn and CBMn-Cu showed similar performance.

Insertion of transition metal species into crystalline alumina at low temperatures is proposed to achieve the dispersion of these species at atomic level paired with exceptional textural properties. Precisely, MeAl2O4/γ-Al2O3 (Me = Mn, Fe, Co, Ni, and/or Cu) nanostructured ceramic catalysts were fabricated with ultra large mesopores (16−30 nm), and high specific surface area (180−290 m2 g−1) and pore volume (1.1-1.6 cm3 g−1). These ceramics were applied as efficient catalysts for the selective catalytic reduction (SCR) of NO with NH3, and their selectivity was discussed in terms of N2O formation, an undesirable byproduct. The catalysts containing Fe, Cu, or Mn showed the highest activities, however, within different temperature ranges. Further tuning of the catalytic activity and selectivity was achieved by creating ceramic catalysts with mixed compositions, e.g., CuFe and MnFe. Upon insertion of the transition metal species into crystalline structure of alumina to maximize atom efficiency, the N2O formation profile did not change significantly for all metal aluminates except MnAl2O4, indicating that these catalysts are suitable for SCR and selectively promote the reduction of NO.

The goal of the study was to modify activated carbon (AC) with nitrogen groups and ceria and to test the obtained materials in low temperature selective catalytic reduction of nitrogen oxides. For that purpose, the starting AC was oxidized with HNO3 of various concentrations, modified with urea and doped with 0.5 wt.% of Ce. It was observed that the increased concentration of acid influenced the catalytic activity, since textural and surface chemistry of activated carbon was changed. The most active sample was that modified with 14 M HNO3 and it reached 96% of NO conversion at 300 &deg, C. Additionally, the addition of Ce improved the catalytic performance of modified AC, and NO was reduced according to oxidation&ndash, reduction mechanism, characteristic for supported metal oxides. Nevertheless, the samples promoted with Ce emitted significantly higher amount of CO2 comparing to the non-promoted ones.

[EN] In the present study, an influence of the iron aggregation in conventional and micro-mesoporous MFI on their catalytic activity in the NO reduction with ammonia (DeNO(x) process) was studied. Modification of MFI zeolite properties was done by the desilication in the presence of NaOH and TPAOH (tertapropylammonium hydroxide). In the next step, the samples were modified with iron by ion-exchange with the use of a conventional solution of Fe cations (FeSO4) and a solution of iron triple-metallic aggregates (oligocations) ([Fe-3(OAc)(6)O(H2O)(3)](+)). Both of the applied modification techniques (desilication and modification with Fe-3 oligocations) increased the catalytic activity of the MFI zeolite in the DeNO(x) process. This increased catalytic activity was connected with changes in sample porosity, Si/Al ratio, topology, as well as aggregation and dispersion of iron species on the catalyst surface, which was investigated by N-2-sorption, XRD, ICP, NMR, HRTEM and UV-vis-DRS techniques., This work was carried out in the frame of project No. 0670/IP3/2016/74 from the Polish Ministry of Science and Higher Education in the years 2016-2019 and in the frame of project No. 2012/05/B/ST5/00269 from the National Science Centre (Poland). U. D. acknowledges to the Spanish Government by the funding (MAT2017-82288-C2-1-P).

MCM-22, MCM-36, and ITQ-2 zeolites with the intended Si/Al molar ratios of 15, 25, and 50 were synthetized and tested as catalysts for dehydration of methanol to dimethyl ether and dehydration of ethanol to diethyl ether and ethylene. The surface concentration of acid sites was regulated by the synthesis of zeolite precursors with different aluminum content in the zeolite framework, while the influence of porous structure on the overall efficiency of alcohol conversion was analyzed by application of zeolitic materials with different types of porosity&mdash, microporous MCM-22 as well as microporous-mesoporous MCM-36 and ITQ-2. The zeolitic samples were characterized with respect to their: chemical composition (ICP-OES), structure (XRD, FT-IR), texture (N2 sorption), and surface acidity (NH3-TPD). Comparison of the catalytic activity of the studied zeolitic catalysts with other reported catalytic systems, including zeolites with the similar Si/Al ratio as well as &gamma, Al2O3 (one of the commercial catalysts for methanol dehydration), shows a great potential of MCM-22, MCM-36, and ITQ-2 in the reactions of alcohols dehydration.

Raw and variously modified layered aluminosilicates have been used as catalysts in the reaction of ethanol oxidation both in the presence and absence of NOx. In this study, we clearly showed that the conversion of VOC on the modified layered aluminosilicates decreases slightly in the presence of NOx. However, the presence of NOx in the reaction mixture did not affect the stability of the used catalysts. Only a small change of selectivity depending on the carrier type as well as on the way of modification was found.

Vermiculite was prepared by modifications with nitric acid, pillaring with Al oligocations and polymer (polyamide), impregnation with Cu. Obtained products were used as catalysts in SCR-NH3 process. All modifications increased catalytic performance compared to base vermiculite which was used as a reference. Sample pillared with polymer and impregnated with 5%wt. Cu showed best catalytic properties in the process, compared to other polymer and Cu modified samples.

The catalytic properties of the activated carbons treated with N-compounds and promoted with manganese oxides were studied in SCR reaction with ammonia in absence and presence of water. The catalysts were characterized by the elemental analysis, low-temperature Ar sorption, thermogravimetric analysis with the analysis of surface species, temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The addition of H2O to SCR decreased activity by 10-20% and increased selectivity to N-2. The catalysts are quite promising for SCR reaction at lower temperatures in the range of 180-260 degrees C. (C) 2011 Elsevier B.V. All rights reserved.

This paper presents experimental results of the sorption-dilatometric kinetics of methane and carbon dioxide on a sample of hard coal from one of the coal mines in the Upper Silesian Coal Basin. The experiment included isothermal and non-isothermal-isobaric stages. For the isothermal stage, it was found that, up to a certain point (about 8 dm3/kg), the sample&rsquo, s expansion was linearly related to the amount of gas absorbed. Studies on dilatometric kinetics under constant pressure, with a reduction in temperature, indicate that a dominant share of the heat-expanding properties of carbonaceous material influences changes in the size of the sample in the coal-gas system. It was also found that the sample expansion, due to temperature change, was 2.25&permil, for the sample in both the vacuum and the non-adsorbing gas atmosphere.

The influence of modification by post-treatment of active carbon with ammonia or urea on catalytic reduction of NO with ammonia was studied. The amount of nitrogen introduced into the structure depended on the pre-treatment of active carbon. The formed N-species were mainly pyridinic or pyrrole/pyridone in nature. No amine, amide or cyano species were found. Both modification procedures (ammonia or urea) led to the increase in activity in SCR and selectivity to N 2 . The extent of the improvement depended on the pre-oxidation of active carbon before N-introduction and was higher for urea than ammonia treatment.