Planar model system and heterogeneous catalysis

Vehicles with sensors produce large amounts of data. Transmission of data is connectedwith costs. By using data compression, less data has to be transmitted, reducing priceof operation. A number of algorithms are evaluated through tests with GPS and accelerometerdata. Performance is measured based on time usage, compression ratio,and euclidean errors (in the case of lossy compression). No algorithm or combinationof algorithms is shown to outperform the others on all data and all metrics. Threedierent recommendations are made. For lossless data compression focused on speed, acombination of Move-To-Front, Zero-Run-Length-Encoding, and Human coding is recommended.For lossless data compression focusing on compression ratio, a combinationof delta coding, Lempel-Ziv coding, and Human coding is recommended. Finally, fordata that can aord losses and that has a low amount of unique symbols, a model basedapproach is recommended

Hidrogén előállításának új lehetőségei kis szénatom számú vegyületek reakcióiban = New route for hydrogen production in the conversion of C1-C2-compounds

Az alternatív energiaforrások iránt megnövekedett igény fordította a figyelmet az etanol reformálása felé. Ideális esetben a reakció terméke H2 és CO2 lenne. E pályázat keretében részletesen vizsgáltuk a H2 előállításának lehetőségeit bioetanolból. Az etanol + víz reakciójában Al2O3 hordozós nemesfém katalizátorokon a H2 képződés sebessége időben csökken, míg az etilén szelektivitása nő közel állandó konverzió mellett. A legnagyobb mértékű változást a Pt katalizátorok esetében észleltük, mely a katalizátor Pt tartalmának, a víz koncentrációjának növelésével és a reakció hőmérsékletének az emelésével jelentősen csökkenthető. Részletesen vizsgáltuk az etanol és az etanol + víz elegy kölcsönhatását Al2O3 és CeO2 hordozós nemesfém katalizátorokon FTIR, TPD és TPR módszerekkel. Megállapítottuk, hogy a hőmérséklettől függően az adszorbeált etanol mellett, különböző etoxi csoportok, CO, acetaldehid, valamint acetát csoportok kimutathatók a katalizátorok felületén. A felületi acetát még 700 K körüli is detektálható. Az adszorbeált etanol TPD görbéjén egy magas hőmérsékletű deszorpciós formát is találtunk, melyet a hordozók esetében nem észleltünk. Ezt az eredményt a felületi acetát formák képződésével és bomlásával értelmeztük A katalizátorok szelektivitásának megváltozását az etanol + víz reakcióban az acetát csoportok képződésének tulajdonítottuk, melyek gátolják a fémen lejátszódó reakciót annak ellenére, hogy ezek a formák a hordozókhoz kötődnek. | The increasing demand for alternative energy sources turned the attention towards the reforming of ethanol. In an ideal case, the products would be H2 and CO2. In the frame of this project we studied the H2 production from ethanol that itself can be produced by biotechnological methods. In the reaction of ethanol and H2O over the Al2O3 supported noble metal catalysts the formation rate of H2 decreased and that of C2H4 increased in time, while the conversion was almost constant. The highest change in the products selectivity was observed on the Pt sample. This trend was attenuated by increasing: the H2O concentration, the metal loading and the reaction temperature. We have studied the interaction of ethanol and the ethanol - H2O mixture over Al2O3 and CeO2 supported noble metal catalysts by FTIR, TPD and TPR methods. It was proved that depending on the temperature, adsorbed ethanol, different ethoxy species, CO, acetaldehyde, and acetate species are present on the surfaces. The acetate is stable even above 700 K. On the TPD curves of the adsorbed ethanol a high temperature desorption stage was observed which did not occur in the case of the pure supports. This result was explained by the formation and decomposition of the acetate species. It was assumed that the selectivity change in the ethanol + H2O reaction can be attributed to the formation of surface acetate groups which hindered the reaction on the metal, although these species were located rather on the support

Beneficial effect of multi-wall carbon nanotubes on the graphitization of polyacrylonitrile (PAN) coating

Polyacrylonitrile (PAN) solutions were deposited on quartz plates by spin coating to yield 2–3 µm thick PAN films. The films were decomposed at 1000°C in N2 atmosphere into electrically conducting carbonaceous coatings. When the precursor solution contained cobalt (0.2 g Co-acetate per 1 g PAN) and/or multi-wall carbon nanotubes (MWCNTs, 2 mg MWCNT per 1 g PAN) the specific electrical resistance of the product film dropped from the original 492 Ω·cm-1 value down to 46 Ω·cm-1. By excluding all other possibilities we came to the conclusion that the beneficial effect of carbon nanotubes is related to their catalytic action in the final graphitization of condensed nitrogen-containing rings into graphitic nanocrystallites

In-situ DRIFTS and NAP-XPS Exploration of the Complexity of CO2 Hydrogenation over Size Controlled Pt Nanoparticles Supported on Mesoporous NiO

4.8 nm Pt nanoparticles were anchored onto the surface of mesoporous nickel-oxide supports (NiO). Pt/NiO samples were compared to pristine NiO and Pt/SBA-15 silica catalysts in CO2 hydrogenation to form carbon-monoxide, methane and ethane at 473-673 K. 1 % Pt/NiO were ~20 times and ~1.5 times more active at 493 K compared to Pt/SBA-15 and NiO catalysts, respectively. However, the Pt-free NiO support has an activity of 120% compared to Pt/NiO catalysts at 673 K. In the case of 1% Pt/SBA-15 catalyst, selectivity towards methane was 13 %, while it was 90% and 98% for NiO and 1% Pt/NiO at 673 K, respectively. Exploration of the results of the reactions was performed by Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) as well as in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). In the case of pure NiO, we found that the surface of the support was mainly covered by elemental Ni under reaction condition, where the Ni/NiOx system is responsible for the high activity of Pt-free catalyst. In the case of Pt/NiO, Pt improves the reduction of NiOx towards metallic Ni. In the case of the 1 % Pt/NiO catalysts, the presence of limited amount of Pt resulted in an optimal quantity of oxidized Pt fraction at 673 K showing the presence of a Pt/PtOx/Ni/NiOx mixed phase where the different interfaces may be responsible for the high activity and selectivity towards methane. In the case of pure NiO under reaction condition, small amounts of formaldehyde as well as hydrogen perturbed CO [HnCO (n=1,2)] were detected. However, in the case of 1 % Pt/NiO catalysts, besides the absence of formaldehyde a significant amount of HnCO (n=2-3) was present on the surface responsible for the high activity and methane selectivity