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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.

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.

The article starts with the short discussion of two geometrical figures, i.e., octagon and ellipse, their genesis in architecture and urban design, and the examples of buildings whose plans were based upon them. Then, the selected octagonal and elliptical city squares are discussed: their genesis, context, layout, architecture surrounding the square, objects appearing in the square and, most specially, urban form and composition. The theory of architectural-landscape interiors has been applied to pinpoint the type of city squares by the assessing of the degree of openings in the square’s perimeter. The review consists of 22 case studies (9 octagonal and 13 elliptical) from the 15th to the 20th century. The last discussed case in each group, both atypical created in Krakow in the 20th century, are discussed even more thoroughly. The conclusions were presented first separately for octagonal and elliptical city squares and finally also for both groups in a comparative way.

Abstract: A series of modified montmorillonites pillared with ZrO2 or variously prepared TiO2 and impregnated with CuO were synthesised, characterized (BET and pore analysis, XRD, TPD, TPR, AAS) and tested in the reaction of catalytic dehydration of glycerol. It was found that catalytic performance was sensitive to the preparation procedure. The acidity resulted in higher initial conversion and higher initial selectivity to acrolein, whereas CuO was found to stabilize higher conversion and to change the product distribution, favouring formation of hydroxyacetone. Titania-pillared, CuO-impregnated montmorillonite showed a long-term selectivity to hydroxyacetone higher than 60% at 74% conversion. [Copyright &y& Elsevier]

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.

Coal fired power plant are still responsible for vast amount of electricity and heat production in Poland in 2019. Increasing number of units is equipped with SCR reactors in order to mitigate NOx emission. Older units have been designed to work in a base load operation· however increasing number of intermittent energy sources on the market· forces power plant owners to operate such units in reduced load for significant number of hours in a year. Most of parameters in coal-fired boiler would change in reduced load operation· particularly flue gas parameters. That would affect the formation of ammonia bisulfate (NH4HSO4) as well as operation of SCR reactors in the boiler. The NH4HSO4 formation is highly undesired as it can plug the catalyst or heating surfaces in the boiler. To investigate this phenomenon· the NH4HSO4 formation was comprehensively studied. Moreover· reduced load operation of boiler in a medium size CHP plant was simulated· using computer modelling tools. Obtained parameters were used to analyse· how different flue gas parameters affect NH4HSO4 formation and what consequences does it have for boiler operation. In particular, effect related with operation of SCR reactors equipped with V2O5-WO3/TiO2 catalyst was deeply studied.

The catalytic activity in dry methane reforming of hydrotalcite-derived catalysts with ceria and/or nickel species introduced into hydrotalcite interlayer spaces was examined. The prepared materials were characterized (XRF, XRD, FT-IR, H2-TPR and N2 sorption) and subsequently tested in CO2 methane reforming at 550 °C. The obtained results showed that the incorporation of nickel species between hydrotalcite layers resulted in active catalyst with no sign of carbon deposition. Additionally, a beneficial effect of ceria promotion was observed. Ceria-promoted sample exhibited higher activity, stability and selectivity towards DRM, which may be explained by the formation of small Ni crystallites and prevention of the formation of inactive NiAl2O4 spinel phase.

Methane tri-reforming process is a combination of three reactions: steam methane reforming (SRM), dry methane reforming (DRM), and partial oxidation of methane (POM). The first two reactions have endothermic character, while the POM is the exothermic reaction, which allows to obtain the energy necessary for the other two processes in situ. CH4 reacts with H2O, CO2, O2, and synthesis gas is produced with desired H2/CO ratios (1.5 – 2.0). The presence of H2O and O2 in the reaction environment can positively influence the stability of the used catalyst, by the inhibition of coke formation. In this paper two scenarios for methane tri-reforming implementation are discussed: (i) Tri-reforming as a effective way for chemical CO2 utilization, without the separation of carbon dioxide from flue gases from fossil fuel-fired power stations, and (ii) dry reforming of methane improved by the addition of water and oxygen, which may be applied as a chemical energy storage process. The literature on the subject of trireforming is shortly reviewed, including thermodynamics of the process, the possible conversions of methane and carbon dioxide, and proposed catalysts, both studied in tri-reforming, and in single processes (SRM, DRM and POM).

The aim of this work was to study the influence of the modification of montmorillonites by carbonaceous and Al species as well as copper deposition. Commercial acid-treated montmorillonites, K5 and K30 (Sigma-Aldrich GmBH), were modified and used as catalysts in Selective Catalytic Reduction process of nitrogen oxides by ammonia. The characterisation was carried out by low-temperature nitrogen sorption, Fourier-transform-infrared spectroscopy and X-ray diffraction. Catalytic performance in SCR-NH3 of so-modified montmorillonites was compared under the following conditions: mass of catalyst: 200 g, flow 100 cm3/min, reaction mixture: 800 ppm NO, 800 ppm NH3, 3 % O2, and He. The modification with copper and polyacrylamide led to the increase in NO conversion. The studied catalysts showed low N2O formation.