The Experts below are selected from a list of 129 Experts worldwide ranked by ideXlab platform
Avelino Corma - One of the best experts on this subject based on the ideXlab platform.
-
activation of hydrogen on zeolites kinetics and mechanism of n heptane cracking on h zsm 5 zeolites under high hydrogen pressure
Journal of Catalysis, 1995Co-Authors: J Meusinger, Avelino CormaAbstract:The cracking of n-heptane on H-ZSM-5 zeolite was studied using a tubular reactor at 543 K, 2.4 MPa total pressure and varying hydrogen and n-heptane partial pressures. The Rate of reaction was determined at times on stream ranging from 0.5 to 62 min. Under the above experimental conditions H-ZSM-5 deactivates rapidly during the first 10 min of reaction time. The initial Rate of n-heptane cracking is independent of the n-heptane partial pressure between 0.25 and 0.47 MPa, while it increases linearly with increasing hydrogen partial pressure. This is interpreted with the assumption that under these reaction conditions the Desorption of adsorbed intermediates is the Rate determining step and that the Rate of Desorption can be increased by hydrogen via hydride transfer from molecular hydrogen, producing a high paraffin/olefin ratio in the reaction products. In addition to this effect, hydrogen diminishes the Rate of catalyst coking.
Jin Z Zhang - One of the best experts on this subject based on the ideXlab platform.
-
reversibility and improved hydrogen release of magnesium borohydride
Journal of Physical Chemistry C, 2010Co-Authors: Rebecca Newhouse, Vitalie Stavila, Sonjong Hwang, Leonard E Klebanoff, Jin Z ZhangAbstract:Desorption and subsequent rehydrogenation of Mg(BH4)2 with and without 5 mol % TiF3 and ScCl3 have been investigated. Temperature programmed Desorption (TPD) experiments revealed a significant increase in the Rate of Desorption as well as the weight percentage of hydrogen released with additives upon heating to 300 °C. Stable Mg(BxHy)n intermediates were formed at 300 °C, whereas MgB2 was the major product when heated to 600 °C. These samples were then rehydrogenated and subsequently characterized with powder X-ray diffraction (pXRD), Raman, and NMR spectroscopy. We confirmed significant conversion of MgB2 to fully hydrogenated Mg(BH4)2 for the sample with and without additives. TPD and NMR studies revealed that the additives have a significant effect on the reaction pathway during both dehydrogenation and rehydrogenation reactions. This work suggests that the use of additives may provide a valid pathway for improving intrinsic hydrogen storage properties of magnesium borohydride.
J Meusinger - One of the best experts on this subject based on the ideXlab platform.
-
activation of hydrogen on zeolites kinetics and mechanism of n heptane cracking on h zsm 5 zeolites under high hydrogen pressure
Journal of Catalysis, 1995Co-Authors: J Meusinger, Avelino CormaAbstract:The cracking of n-heptane on H-ZSM-5 zeolite was studied using a tubular reactor at 543 K, 2.4 MPa total pressure and varying hydrogen and n-heptane partial pressures. The Rate of reaction was determined at times on stream ranging from 0.5 to 62 min. Under the above experimental conditions H-ZSM-5 deactivates rapidly during the first 10 min of reaction time. The initial Rate of n-heptane cracking is independent of the n-heptane partial pressure between 0.25 and 0.47 MPa, while it increases linearly with increasing hydrogen partial pressure. This is interpreted with the assumption that under these reaction conditions the Desorption of adsorbed intermediates is the Rate determining step and that the Rate of Desorption can be increased by hydrogen via hydride transfer from molecular hydrogen, producing a high paraffin/olefin ratio in the reaction products. In addition to this effect, hydrogen diminishes the Rate of catalyst coking.
C Pevida - One of the best experts on this subject based on the ideXlab platform.
-
cyclic operation of a fixed bed pressure and temperature swing process for co2 capture experimental and statistical analysis
International Journal of Greenhouse Gas Control, 2013Co-Authors: Susana Garcia, M V Gil, J J Pis, F Rubiera, C PevidaAbstract:Abstract An adsorption process that effectively sepaRates CO 2 from high pressure CO 2 /H 2 shift gas streams to meet the requirements of pre-combustion CO 2 capture has been evaluated. A commercial activated carbon, Norit R2030CO2, was used as the adsorbent material and different batchwise regeneration conditions were investigated. Statistical analysis by means of response surface methodology (RSM) was employed to assess the combined effect of three independent variables, namely, Desorption temperature ( T des ), Desorption pressure ( P des ) and purge to feed ratio (P/F ratio) on the adsorbent performance. A bench-scale fixed-bed reactor enabled the simulation of the adsorption, heating and depressurization steps of a pressure and temperature swing adsorption-based process. Experimental data were then assessed by the statistical technique and a set of mathematical equations that describes the behaviour of the given set of data were geneRated. No interaction effects between the independent variables on the responses were found. P/F ratio was found to be the most influential variable on working adsorption capacity, CO 2 recovery, adsorbent productivity and H 2 and CO 2 purities. The maximum CO 2 purity was obtained at 60 °C, 5 bar and a P/F ratio of 0.05. On the other hand, Desorption temperature had the largest impact on the maximum Rate of Desorption.
Stephen C Parker - One of the best experts on this subject based on the ideXlab platform.
-
free energy of adsorption of water and metal ions on the 1014 calcite surface
Journal of the American Chemical Society, 2004Co-Authors: Sebastien N Kerisit, Stephen C ParkerAbstract:We calculated the free energy profiles of water and three metal ions (magnesium, calcium, and strontium) adsorbing on the [1014] calcite surface in aqueous solution. The approach uses molecular dynamics with parametrized equations to describe the interatomic forces. The potential model is able to reproduce the interactions between water and the metal ions regardless of whether they are at the mineral surface or in bulk water. The simulations predict that the free energy of adsorption of water is relatively small compared to the enthalpy of adsorption calculated in previous papers. This suggests a large change in entropy associated with the water adsorption on the surface. We also demonstRate that the free energy profile of a metal ion adsorbing on the surface correlates with the solvent density and that the Rate of formation of an innersphere complex depends on overcoming a large free energy barrier, which is mainly electrostatic in nature. Furthermore, comparison among the Rates of Desorption of magnesium, calcium, and strontium from the calcite surface suggests that magnesium has a much lower Rate of Desorption due to its strong interactions with both water and the surface.
