Papers by Keyword: Hydrogenation

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Authors: Tong Huan Zhang, Min Jian Yang, Peng Bo Li, Wei Xian Ran, Qian Qian Zhang, Chang Zhen Li, Chao Ding
Abstract: Mg-based hydrogen storage material was prepared by ball milling, and then the material was used to react with CS2. The morphology and hydrogen desorption properties of the hydrogen storage material as well as the CS2 hydrogenation product were analyzed. Results show that in situ hydrogenation and desulfurization of CS2 happens with the MgH2 in the hydrogen storage material as hydrogen donator and desulfurizer at 300 °C and ordinary pressure, and MgS, CH4 and H2S are generated from the reaction. There is a coupling relationship between dehydrogenation of the hydrogen storage material and hydrogenation of CS2. The addition of nickel and molybdenum show negative effect on the sulfur fixation capability of the Mg-based hydrogen storage material though they could decrease the dehydrogenation temperature of the material.
Authors: N.J. Creamer, I.P. Mikheenko, K. Deplanche, P. Yong, J. Wood, K. Pollmann, S. Selenska-Pobell, Lynne E. Macaskie
Abstract: Palladized biomass of typical Gram negative bacteria (Desulfovibrio desulfuricans and Escherichia coli) is well documented as a potentially useful catalyst for reduction of metallic species such as Cr(VI). This bionanocatalyst can be sourced from Pd-waste and scrap leachates via biocrystallization. A major industrial application of precious metal catalysts is in hydrogenation and hydrogenolysis reactions whereby, respectively, H is added across unsaturated bonds and halogen substituents can be removed from aromatic rings. Gram positive bacteria have not been evaluated previously as potential supported Pd-bionanocatalysts. We compare the activity of ‘Bio-Pd(0)’ supported on the fundamentally different Gram negative (Desulfovibrio) and Gram positive (Bacillus) bacterial surfaces, and evaluate the activity of the two types of ‘Bio-Pd(0)‘ in a standard reference reaction, the hydrogenation of itaconic acid, against a commercially available catalyst (5% Pd on carbon). The results show that the bionanocatalysts have a similar activity to the commercial material and biomanufacturing from waste sources may be an economic alternative to conventional processing for catalyst production as precious metal prices continue to rise.
Authors: Feng Bin Liu, Jia Dao Wang, Da Rong Chen, Bing Liu
Abstract: By means of the density functional theory on the basis of generalized gradient approximation, the reaction paths of the dehydrogenation from the diamond (100) surface was deduced due to the reaction heat. Moreover, the most stable structure of the hydride diamond (100) surface was obtained. The results indicate that the dehydrogenation is easier to take place at the same C-C dimer and forms the parallel geometries. The parallel 1×1:1.5H, 2×1:H and parallel 2×1:0.5H are the intermediate products during the hydrogen desorption process, while, 2×1:H is the most stable structure of the hydride diamond (100) surfaces. The calculated reaction heat is in accordance with the experimental results.
Authors: Emmanuel Dioresma Monterola, Naomi Tabudlong Paylaga, Giovanni Jariol Paylaga, Rolando Viño Bantaculo
Abstract: Silicene is a two-dimensional (2D) allotrope of silicon known to have a lower thermal conductivity than graphene; thus, more suitable for thermoelectric applications. This paper investigates the effect of hydrogenation on the thermal conductivity of silicene nanoribbon (SiNR) using equilibrium molecular dynamics (EMD) simulations. The simulations were carried out in Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) using a modified Tersoff potential that considers both Si-Si and Si-H interactions. The thermal conductivity of fully hydrogenated silicene nanoribbon (H-SiNR), also known as silicane nanoribbon, was found to be higher than that of pristine SiNR in all the temperatures and dimensions considered here. This anomalous enhancement in the thermal conductivity is similar to that found in hydrogenated silicon nanowires (H-SiNWs). A mechanism for this anomalous effect has been proposed relating the hydrogenation of SiNR with the stiffening and increase of the acoustic out-of-plane flexural (ZA) phonon modes. Also, for both SiNR and H-SiNR, the thermal conductivities generally increase as the dimensions are increased while they generally decrease as the temperatures are increased, in agreement to other reports.
Authors: Shi Gang Kang, Zhi Min Zong, Heng Fu Shui, Zhi Cai Wang, Xian Yong Wei
Abstract: The hydrogenation of preasphaltene (PA), from Chinese Xiaolongtan lignite liquefied heavy product, was investigated with hydrogen storage materials in a batch autoclave. The effects of reaction conditions such as hydrogen storage materials and temperature on the yields of gas+oil, asphaltene, char and the conversions of preasphaltene were discussed. Preliminary studies indicate that increasing temperature not only improves hydrogen donor performance of hydrogen storage materials but also enhances conversion of feedstock PA and gas+oil yield. The conversion of PA and the yield gas+oil get to 72.02% and 41.46%, respectively, under 5% MgH2, 5MPa initial hydrogen pressure, temperature 420°C and reaction time 30min. Meanwhile MgH2 is stronger than NaBH4 in hydrodeoxygenation of PA under the same conditions. Elemental and FTIR analyses were used to illustrate the structural characteristics of feedstock PA and remaining preasphaltene (RPA).
Authors: Fei Ding, Cai Rong Luo, Hai Rong Zhang, Lian Xiong, Xin De Chen
Abstract: Bifunctional Pt/HZSM-5, Pt/HBeta, Pt/HMCM-41 and Pt/HSAPO-11 catalysts were prepared using pseudoboehmite as a binder. The H2-TPR profiles, scanning electron microscope (SEM) and brunauer-emmett-teller (BET) pointed out that reducibility of catalysts and textural properties. These bifunctional catalysts have been tested in long-chain olefins hydroisomerization. The experiments were carried out at 320 o C under 2.0 MPa of hydrogen and at 3.0 h-1 WHSV. Complete hydrogenation of long-chain olefins was observed over Pt/HMCM-41 and Pt/HSAPO-11. Hydroisomerization reactions also occured in the case of Pt supported strong acidic molecular sieves (HZSM-5 and HBeta). The result suggests product distribution of long-chain olefins hydroisomerization is dependent on the balance between the acid and metallic functions in catalysts.
Authors: Volker Engels, Andrew E.H. Wheatley, Angel Berenguer-Murcia, David A. Jefferson, Brian F.G. Johnson
Abstract: Novel catalytic systems based on PdZn alloys have been synthesized by polyol reduction over the entire compositional range [1, 2] and characterized by means of HRTEM, EDS and ICP. The expected bulk compositions were reproducible to within a 2 mol% margin and the purified particle suspensions stable for several months after preparation. The EDS results indicated the presence of considerable amounts of oxygen, especially in those samples containing high fractions of zinc. The particle size distributions were shown to be narrow and the mean sizes slightly decreased with higher molar fractions of palladium (diameter range 2.6 to 3.2 nm). In the catalytic hydrogenation of phenylacetylene, a strong dependence of the substrate conversion time on the Pd concentration was established, and selectivity towards the semihydrogenation product (styrene) was found to be close to 100 %. The selectivity dropped only shortly before the initial substrate was fully depleted.
Authors: Emanuele Cornagliotti, Harold F.W. Dekkers, Caterina Prastani, Joachim John, Emmanuel Van Kerschaver, Jef Poortmans, Robert P. Mertens
Abstract: In this work the impact of hydrogenation from hydrogen-rich amorphous silicon nitride (a-SiNx:H) on dislocations and grain boundaries in multi-crystalline silicon (mc-Si) solar cells is presented. Layers are deposited by means of plasma enhanced chemical vapor deposition (PECVD). Electrical bulk passivation is provided during thermal annealing, in which hydrogen diffuses from a-SiNx:H. The passivation effect is discussed in terms of recombination centers and non-recombinative charge traps reduction as well as in terms of local short circuit current improvement in specially manufactured solar cells.
Authors: Yerbol Tileuberdi, Yerdos Ongarbayev, Ye. Imanbayev, Z. Mansurov, B. Tuleutaev, F. Behrendt, I. Schneider, K. Khasseinov
Abstract: In the paper catalytic hydrogenation of natural bitumen (NB) of Kazakhstan oil sands were investigated. The process provided under 350 bar of H2 pressure and a temperature of 430 °C. At the experiment activated carbon supported catalyst was used. It has 699.807 m2/g of surface area and 0.0635 nm of medium pore size. In the processes the yield of hydrogenated natural bitumen was 91%, including 1st fraction is 13.12 wt.%; yield of 2nd fraction increased, that the temperature range from 216 to 316 °С formed in amount of 45.68 wt.%; vacuum residue of the distillation takes the 41.20 wt.% in natural bitumen.
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