Zeolite crystals with an embedded and interconnected macropore system are prepared by using mesoporous silica particles as a silica source and as a sacrificial macroporogen. These novel hierarchical zeolite crystals are expected to reduce diffusion limitations in all zeolite-catalyzed reactions, especially in the transformation of larger molecules like in the catalytic cracking of polymers and the conversion of biomass.

High-temperature, stable core-shell catalysts for ammonia decomposition have been synthesized. The highly active catalysts, which were found to be also excellent model systems for fundamental studies, are based on α-Fe(2)O(3) nanoparticles coated by porous silica shells. In a bottom-up approach, hematite nanoparticles were firstly obtained from the hydrothermal reaction of ferric chlorides, L-lysine, and water with adjustable average sizes of 35, 47, and 75 nm. Secondly, particles of each size could be coated by a porous silica shell by means of the base-catalyzed hydrolysis of tetraethylorthosilicate (TEOS) with cetyltetramethylammonium bromide (CTABr) as porogen. After calcination, TEM, high-resolution scanning electron microscopy (HR-SEM), energy-dispersive X-ray (EDX), XRD, and nitrogen sorption studies confirmed the successful encapsulation of hematite nanoparticles inside porous silica shells with a thickness of 20 nm, thereby leading to composites with surface areas of approximately 380 m(2)  g(-1) and iron contents between 10.5 and 12.2 wt %. The obtained catalysts were tested in ammonia decomposition. The influence of temperature, iron oxide core size, possible diffusion limitations, and dilution effects of the reagent gas stream with noble gases were studied. The catalysts are highly stable at 750 °C with a space velocity of 120,000 cm(3)  g(cat)(-1)  h(-1) and maintained conversions of around 80 % for the testing period time of 33 h. On the basis of the excellent stability under reaction conditions up to 800 °C, the system was investigated by in situ XRD, in which body-centered iron was determined, in addition to FeN(x), as the crystalline phase under reaction conditions above 650 °C.

The use of nanostructured yolk-shell materials offers a way to discriminate support and particle-size effects for mechanistic studies in heterogeneous catalysis. Herein, gold yolk-shell materials have been synthesized and used as model catalysts for the investigation of support effects in CO oxidation. Carbon has been selected as catalytically inert support to study the intrinsic activity of the gold nanoparticles, and for comparison, zirconia has been used as oxidic support. Au, @C materials have been synthesized through nanocasting using two different nonporous-core@mesoporous-shell exotemplates: Au@SiO(2)@ZrO(2) and Au@SiO(2)@m-SiO(2). The catalytic activity of Au, @C with a gold core of about 14 nm has been evaluated and compared with Au, @ZrO(2) of the same gold core size. The strong positive effect of metal oxide as support material on the activity of gold has been proved. Additionally, size effects were investigated using carbon as support to determine only the contribution of the nanoparticle size on the catalytic activity of gold. Therefore, Au, @C with a gold core of about 7 nm was studied showing a less pronounced positive effect on the activity than the metal oxide support effect.

Yolk-shell catalysts have attracted interest in both academia and industry, since they combine high-temperature stability with a reduced complexity for kinetic and mechanistic investigations. This contribution presents a possibility to adjust the size of an active gold core inside a porous zirconia shell via an ex-post-modification approach.

Filtration is an established water-purification technology.H owever,d ue to lowf low rates,t he filtration of large volumes of water is often not practical. Herein, we report an alternative purification approach in whichamagnetic nanoparticle composite is used to remove organic, inorganic, microbial, and microplastics pollutants from water.T he composite is based on ap olyoxometalate ionic liquid (POM-IL) adsorbed onto magnetic microporous core-shell Fe 2 O 3 / SiO 2 particles,g iving am agnetic POM-supported ionic liquid phase (magPOM-SILP). Efficient, often quantitative removal of several typical surface water pollutants is reported together with facile removal of the particles using apermanent magnet. Tuning of the composite components could lead to new materials for centralized and decentralized water purification systems.

Fluctuating wind and solar energy can be used to produce hydrogen by water electrolysis and subsequently for the synthetic natural gas production via methanation in the power-to-gas process. This paper investigates the unsteady-state operation of the methanation in an adiabatic and cooled fixed-bed reactor, respectively, with product recirculation by simulation of a one-dimensional fixedbed reactor model. The results show that adiabatic fixed-bed reactors with product recirculation can operate in a wide range of partial and excess load. The recirculation of product gas cools the adiabatic fixedbed reactor effectively and an optimal recycle ratio for the highest methane productivity exists. Cooled reactors are very sensitive to load changes of the volumetric flow rate and thus less flexible. However, the recycle of product gas allows reducing the sensitivity for a more stable operation under fluctuating feed conditions. The start-up time of cooled fixed-bed reactors is considerably lower. In summary, the flexibility of the dynamic methanation is enhanced in a loop-reactor arrangement.

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The power-to-gas process for the chemical storage of renewable energy in methane as a storage molecule requires a carbon source, for which industrial exhaust gases are very promising because of their availability in large quantities. The composition of these gas streams, however, is often characterized by a mixture of CO and CO2. Because of the rather complex reaction mechanism, though, the methanation of CO/CO2 mixtures using nickel catalysts is not yet fully understood, and appropriate reaction kinetics required for the reactor design are still lacking. Therefore, we report the experimental results on the methanation of various mixtures of CO and CO2. The data are further evaluated by a model-based approach in order to derive reaction kinetics capable for the reactor design in a typical range of operating conditions. The results also reveal two kinetic regimes depending on the fraction of CO in the CO/CO2 mixture, which is accounted for in the proposed kinetics.