Deuterium distribution in two major products obtained during the cyclic dimerisation of methyloxirane over acidic molecular sieves

The ring-transformation reactions of methyloxirane on DZSM-5 and DAlMCM-41 aluminosilicates were studied in a pulse microreactor at 363 K. Cyclic dimerisation was found to be the major reaction pathway. Deuterium distribution in two important products of this reaction route was monitored. The positions of the deuterium atoms were determined giving help in proposing a more accurate dimerisation mechanism

Szén nanocsövek katalitikus szintézise, felületének és nedvesíthetőségének módosítása szervetlen anyagokkal = Carbon nanotubes: Catalytic synthesis, modification of their surface and wettability properties by inorganic materials

A projekt négy éve alatt - összhangban az eredeti munkatervvel - a szén nanocsövek CVD szintézisének tanulmányozása során kerestük annak a lehetőségét, hogyan növelhető a CNT hozama, illetve hogyan javíthatók a termék mechanikai tulajdonságai. Ezekhez a munkákhoz elengedhetetlenül kapcsolódnak olyan vizsgálatok, melyek a mintáink fizikai-kémiai jellemzését jelentik. A továbbiakban a szén nanocsövek alkalmazhatóságához kapcsolódó vizsgálatokat végeztünk, ami sok esetben első lépésként azok felületi tulajdonságainak módosítását jelenti. Az így módosított anyagok további alkalmazási lehetőségeit is tanulmányoztuk. A vizsgálatokat jelentős részben a pályázatban szereplő kutatók, illetve az ő témavezetésükkel dolgozó hallgatók végezték. (Ezekből számos projektmunka, TDK-dolgozat, diplomamunka készült, és részét képezi nem egy előkészületben lévő PhD disszertációnak is.) | During the four year of the project (in tune with the original proposal) further optimization of CVD synthesis of carbon nanotubes was studied. It is important to improve both the yield and mechanical properties of this material. These investigations were completed with various physico-chemical characterizations. Henceforth the possibility of surface modification of carbon nanotubes was also studied. Due to wettability problem it can be essential for potential application. The possibility of further use of these modified materials was also investigated. The work done mainly by the original staff of the project and of course by students supervised by the above-mentioned researchers. In addition to publication in this report, numerous diploma work and PhD thesis contain these results

The ring opening and oligomerisation reactions of an epoxide and an episulfide on aluminosilicates in the liquid phase

Data-efficient learning in continuous state-action spaces using very high-dimensional observations remains a key challenge in developing fully autonomous systems. In this paper, we consider one instance of this challenge, the pixels to torques problem, where an agent must learn a closed-loop control policy from pixel information only. We introduce a data-efficient, model-based reinforcement learning algorithm that learns such a closed-loop policy directly from pixel information. The key ingredient is a deep dynamical model that uses deep auto-encoders to learn a low-dimensional embedding of images jointly with a predictive model in this low-dimensional feature space. Joint learning ensures that not only static but also dynamic properties of the data are accounted for. This is crucial for long-term predictions, which lie at the core of the adaptive model predictive control strategy that we use for closed-loop control. Compared to state-of-the-art reinforcement learning methods for continuous states and actions, our approach learns quickly, scales to high-dimensional state spaces and is an important step toward fully autonomous learning from pixels to torques.COOPLO

Transformations of cyclohexene oxide over silica-supported Cu, Pd, and Rh catalysts in H2/D2 atmosphere

Transformations of cyclohexene oxide were studied in a recirculation reactor and a flow system over silica-supported transition and early transition metal catalysts. Hydrogen pressure dependence of the transformations was measured over Cu/SiO2 at 403 K in the 0-98.7 kPa range. Deuterium distribution in the reactant and products were determined at 20 kPa D-2 pressure. The reactions were studied in the flow reactor under D-2 stream over Cu/SiO2 (373 K, 403 K, 443 K, 523 K), Pd/SiO2 (403 K), and Rh/SiO2 (403 K) catalysts too. Deuterium distributions were determined at the commonly used 403 K. Over each catalyst, in both reactor types three main transformation pathways were found. Single C-O scission occurred via isomerization and hydrogenation. Double C-O cleavage, that is, deoxygenation was also found to be important. Product distribution varied from catalyst to catalyst and it was influenced by the conditions, as well as the reactor types. Deuterium distribution revealed significant differences in the elementary surface processes over the catalysts. Detailed mechanistic interpretation of the transformations is offered

Changes in the hydrogenative ring-opening mechanism of cyclohexene oxide over Cu/SiO2 resulting from the addition of cyclohexene, a major product

The ring-opening mechanism influencing effect of a major product in the cyclohexene oxide-D-2 system was investigated over a Cu/SiO2 catalyst. This product is cyclohexene, thus, the hydrogenative ring opening of a 1:1 cyclohexene oxide-cyclohexene mixture was studied in the presence of D-2 at 403 K in a closed circulation reactor. It was found that the mechanism of single C-O scission was not affected, but that of the double C-O scission was changed. Simultaneous bond cleavage was the major route of ring opening in the additive-free system and it became consecutive on cyclohexene addition. Added cyclohexene was hydrogenated with a very low rate, but it transformed the surface of the catalyst and, thus, facilitated the change in the mechanism. An explanation concerning the seemingly anomalous lack of deuterium in a product (cyclohexane) not seen in the additive-free system is also suggested

Ring-opening reactions of ethyl- and vinyloxirane on HZSM-5 and CuZSM-5 catalysts

Transformations of ethyloxirane, vinyloxirane and their mixture were studied over HZSM-5 and CuZSM-5 zeolites in the presence of hydrogen at 363 K. Ethyloxirane underwent single ring-opening and deoxygenation, while ring expansion was the main transformation pathway for vinyloxirane. Reactions of the mixture revealed that the active sites for adsorbed oxygen mediated ring transformations can be separated on HZSM-5 from those, where the adsorption of the vinyl group and the ring oxygen is a requirement. This cannot be done on CuZSM-5

Ring-opening and dimerization reactions of methyl-substituted oxiranes on HZSM-5 zeolite

Energy efficiency in mobile radio networks has recently gained great interest due to escalating energy cost and environmental concerns. Rapidly growing demand for capacity will require denser and denser networks which further increase the energy consumption. In this regard, the deployment of small cells under macro-cellular umbrella coverage appears a promising solution to cope with the explosive demand in an energy efficient manner. In this paper, we investigate the impact of joint macro-and femtocell deployment on energy efficiency of wireless access networks, based on varying area throughput requirements. We take into account the the co-channel interference, fraction of indoor users, femto base station density and backhaul power consumption. It is shown that utilizing indoor base stations provide significant energy savings compared to traditional macro only network in urban areas with medium and high user demand where the gain increases up to 75 percent as more data traffic is offloaded to femtocells.QC 20131218Energy-efficient wireless networking (eWIN