Linearization by means of optimal control for a model in plasma physics

The aim of the present paper is to obtain solutions for the equation modeling of a Vlasov plasma from its linearized form, by means of control theory and using the author's previous results regarding optimal control problems for integro-differential equations.     

Relay Catalysis: Enantioselective Synthesis of Cyclic Benzo‐Fused Homoallylic Alcohols by Chiral Brønsted Acid‐Catalyzed Allylboration/Ring Closing Metathesis

Six‐ and seven‐membered benzo‐fused cyclic homoallylic alcohols can be readily synthesized by a tandem chiral Brønsted acid‐catalyzed allyl (crotyl)boration/ring closing metathesis sequence performed under orthogonal relay catalysis conditions. Excellent enantio‐ and diastereoselectivities are obtained in most of the cases. In addition, the parent crotylboration/RCM process is also described. The required substrates, ortho‐vinylbenzaldehydes, are readily available in one step from commercially available starting materials. Both catalysts and reactants are also available from commercial suppliers. The reaction shows broad functional group compatibility and is also suitable for heteroaromatic substrates. Substitution at any position of the aromatic ring is tolerated; however, substitution at position 6 results in a substantial drop in enantioselectivity.     

The effect of ethanol on carbon-catalysed decomposition of methane

Because of its ecological character, the reaction of catalytic decomposition of methane (CDM) is expected to be an important future method of hydrogen generation. However, the main drawback of this technology is a relatively fast deactivation of the catalyst used, as a consequence of its pores blocking by the low-active methane-originated carbon deposit. This paper reports on an attempt of restricting the catalyst deactivation by introducing into the reaction system ethyl alcohol capable of forming in situ a potentially active in this reaction carbonaceous deposit. The catalyst used was activated carbon obtained from the waste material (hazelnut shells). The reactions of methane and ethanol decomposition were performed by the alternate method (for certain time methane was introduced into the reactor, and then it was replaced by ethanol). Three temperatures of the reactions were applied (750, 850 or 950 °C) and another variable was the duration of the ethanol decomposition. As follows from the results, an addition of ethanol has diverse effect on the catalytic activity of activated carbon and the amount of hydrogen formed depends on the temperatures of methane and ethanol decompositions and on the time of the reagent dosing.     

Ethanol reforming over Ni/CeGd catalysts with low Ni content

The catalytic performance of Ni/CeGd SOFC anodes with low Ni content (18%wt) prepared by a hydrothermal method for ethanol conversion reactions was evaluated. Calcination temperature and reaction conditions significantly affected the activity and stability of the samples. Increasing calcination temperature decreased ethanol conversion. This was likely due to the larger CeGd crystallite size. All samples deactivated during reaction under pure ethanol at 773 K. The addition of water or oxygen to the feed and the increase of reaction temperature improved catalyst stability. Scanning electron microscopy and thermogravimetric analysis showed that the deactivation was due to carbon formation. In the presence of oxygen or water, the mechanism of carbon removal was favored. Moreover, carbon formation was not favored at high reaction temperature due to the reverse of the Boudouard reaction as well as the promoting effect of the support on the carbon gasification reaction.