Kinetic Study on CO-Selective Methanation over Nickel-Based Catalysts for Deep Removal of CO from Hydrogen-Rich Reformate

The CO-selective methanation process is considered as a promising CO removal process for compact fuel processors producing hydrogen, since the process selectively converts the trace of CO in the hydrogen-rich gas into methane without additional reactants. Two different types of efficient nickel-based catalysts, showing high activity and selectivity to the CO methanation reaction, were developed in our previous works; therefore, the kinetic models of the reactions over these nickel-based catalysts have been investigated adopting the mechanistic kinetic models based on the Langmuir chemisorption theory. In the methanation process, the product species can react with the reactant and also affect the adsorption/desorption of the molecules at the active sites. Thus, the kinetic parameter study should be carried out by global optimization handling all the rate equations for the plausible reactions at once. To estimate the kinetic parameters, an effective optimization algorithm combining both heuristic and deterministic methods is used due to the large solution space and the nonlinearity of the objective function. As a result, 14 kinetic parameters for each catalyst have been determined and the parameter sets for the catalysts have been compared to understand the catalytic characteristics.

A Comparison Study of the Metal Oxide Catalysts for the Conversion of Used Cooking Oil into High Grade Chemicals

Cracking of edible oils occurs at high temperature and forms valued low molecular weight chemical species. The aim of the current study was to find a catalyst which can break these heavy molecules at the lower ranges of temperatures. From the analysis prospective, the non-condensable hydrocarbons (gaseous product species) were not determined and reactions study was carried out in a batch reactor. There was no evident conversion up to a temperature of 450 °C in the absence of catalyst whereas the reaction mixture was left inside a batch reactor for a long duration of an hour. Reaction parameters, such as catalyst types (ZnO and Al2O3), amount of catalyst, reaction temperature, residence or holding time, and heating rate to reach a reaction temperature were systematically examined. Powdered form of catalyst samples (ZnO and Al2O3) were characterized by using XRD, EDX, and Nitrogen adsorption isotherms. Temperatures studied over ZnO catalyst were 400 °C, 425 °C, 450 °C, 475 °C, and 500 °C. The maximum oil conversion was 81 % at a temperature of 450 °C. We observed that the conversion increases from 400 °C to 450 °C, whereas above 450 °C it starts to decrease. However, in comparison to ZnO catalyst the reaction rate was much higher over the Al2O3, i.e. a considerable conversion occurred at lower ranges of temperatures. Thus here a different set of temperatures (330 °C, 370 °C, 390 °C, 410 °C, and 430°C) were used. When reacting for an hour at a temperature of 390 °C, and in the presence of 8 wt.% of Al2O3 (same catalyst mass was used in ZnO reacting system) the conversion reached to 71 %. Above 390 °C the conversion decreased. Over both tested metal oxide catalysts the caloric value, density, flash point, and kinematic viscosity of the liquid product species were similar to petro fuels. The XRD and EDX signature of the catalyst samples corresponds to the standard ZnO and Al2O3 patterns. Finally, when compared to ZnO the better activity over the Al2O3 (higher conversion at lower temperature) catalyst can be linked with a high external surface area.

Interaction of HCO+ Cations With Interstellar Negative Grains. Quantum Chemical Investigation and Astrophysical Implications

In cold galactic molecular clouds, dust grains are coated by icy mantles and are prevalently charged negatively, because of the capture of the electrons in the gas. The interaction of the charged grains with gaseous cations is known to neutralize them. In this work, we focus on the chemical consequences of the neutralization process of HCO+, often the most abundant cation in molecular clouds. More specifically, by means of electronic structure calculations, we have characterized the energy and the structure of all possible product species once the HCO+ ion adsorbs on water clusters holding an extra electron. Two processes are possible: (i) electron transfer from the negative water cluster to the HCO+ ion or (ii) a proton transfer from HCO+ to the negative water cluster. Energetic considerations favor electron transfer. Assuming this scenario, two limiting cases have been considered in astrochemical models: (a) all the neutralized HCO+ is retained as neutral HCO adsorbed on the ice and (b) all the neutralized HCO+ gets desorbed to the gas phase as HCO. None of the two limiting cases appreciably contribute to the HCO abundance on the grain surfaces or in the gas.

Direct field evidence of autocatalytic iodine release from atmospheric aerosol

Reactive iodine plays a key role in determining the oxidation capacity, or cleansing capacity, of the atmosphere in addition to being implicated in the formation of new particles in the marine boundary layer. The postulation that heterogeneous cycling of reactive iodine on aerosols may significantly influence the lifetime of ozone in the troposphere not only remains poorly understood but also heretofore has never been observed or quantified in the field. Here, we report direct ambient observations of hypoiodous acid (HOI) and heterogeneous recycling of interhalogen product species (i.e., iodine monochloride [ICl] and iodine monobromide [IBr]) in a midlatitude coastal environment. Significant levels of ICl and IBr with mean daily maxima of 4.3 and 3.0 parts per trillion by volume (1-min average), respectively, have been observed throughout the campaign. We show that the heterogeneous reaction of HOI on marine aerosol and subsequent production of iodine interhalogens are much faster than previously thought. These results indicate that the fast formation of iodine interhalogens, together with their rapid photolysis, results in more efficient recycling of atomic iodine than currently considered in models. Photolysis of the observed ICl and IBr leads to a 32% increase in the daytime average of atomic iodine production rate, thereby enhancing the average daytime iodine-catalyzed ozone loss rate by 10 to 20%. Our findings provide direct field evidence that the autocatalytic mechanism of iodine release from marine aerosol is important in the atmosphere and can have significant impacts on atmospheric oxidation capacity.

Cultural Significance Analysis to Support the Valuation of Non Timber Forest Products of the Malay Community in Tanjung Jabung, Jambi, Sumatera

The study of utilizing the diversity of non-timber forest product species by testing the value of cultural importance or Index of Cultural Significance (ICS) analysis aims to identify the species of non-timber forest products with highest importance value for local communities. The results of this study documented (1) list of species of non-timber forest products that have an important role in the Malay community in Tanjung Jabung, Jambi, including foodstuffs (51-77 plants), vegetable ingredients (21 plants), medicinal materials (> 77 plants), equipment materials (62 plants), pulp and paper materials (27 plants), and other non-timber forest products; (2) list of species of the potential non-timber forest products to be further developed as fruit-producing plants (12 species), vegetables (10 species), medicinal plants (6 species), pulp and paper-based plants (6 species), plywood (18 species), basic materials for manufacturing equipment, arts and other local technology (8 species); and (3) basic data on economic valuation studies of non-timber forest products. The potential species that have high importance value to be cultivated plants were rambai (Baccaurea spp.), cempunik (Artocarpus hispidum), durian (Durio zibethinus, Durio oxleyanus, and Durio spp.), and rambutan (Nephelium lappaceum and Nephelium spp.) for fruits, rotan jernang (Calamus draco and Calamus spp.) as a medicinal material, and other uses. Specifically the diversity of potential species of non-timber forest products will be discussed in this paper.

Formation of low molecular weight mono- and di-carboxylic acids and related compounds from photochemical oxidation of stearic and linoleic acids in aqueous-phase

<p>Secondary organic aerosols (SOA) that account for a substantial and often a dominant fraction of total OA mass are formed by photooxidation of various precursors derived from anthropogenic and biogenic sources in the atmosphere. They have serious impacts on the Earth’s climate system directly by scattering and absorbing solar radiation and indirectly by acting as cloud condensation nuclei, and adverse effects on human health. In recent times, considerable attention has been paid on laboratory studies, preferably in gas-phase, in order to understand the chemistry of SOA formation. However, the studies on SOA formation in aqueous phase are limited, which are mainly focused on high abundant volatile organic compounds (e.g., isoprene) and/or their oxidation products, but not on fatty acids (except oleic acid). To better understand the air-water interface photochemistry of fatty acids and their transformations to lower homologous monoacids and more oxygenated species such as diacids and related compounds in atmospheric waters (fog, cloud and aqueous aerosol), we conducted batch UV irradiation experiments on a saturated (stearic acid, C<sub>18</sub>H<sub>36</sub>O<sub>2</sub>) and an unsaturated (linoleic acid, C<sub>18</sub>H<sub>32</sub>O<sub>2</sub>) fatty acids for different time periods (age, 0-120 h) in aqueous-phase. All the irradiated samples were analyzed for measurements of mono- and di-acids, oxoacids and α-dicarbonyls. We found high abundances of monoacids followed by diacids, pyruvic acid and α-dicarbonyls in less aged samples, whereas C<sub>3</sub> and C<sub>4</sub> diacids were abundant in the more aged samples. Our results imply that the photochemical oxidation of fatty acids and subsequent transformations of the product species in atmospheric waters are significant and their contribution to more oxygenated SOA is increased with aging in the atmosphere.</p>

Developing Single Nucleotide Polymorphisms for Identification of Cod Products by RAD-Seq

The increase in the rate of seafood fraud, particularly in the expensive fishes, forces us to verify the identity of marine products. Meanwhile, the definition of cod lacks consistency at the international level, as few standards and effective application methods are capable of accurately detecting cod species. Genetic fingerprinting is important for both certifying authenticity and traceability of fish species. In this study, we developed a method that combines DNA barcoding and the restriction-site associated DNA sequencing (RAD-Seq) approach for the identification of cod products. We first obtained 6941 high-quality single nucleotide polymorphism (SNP)s from 65.6 gigabases (Gb) of RAD-Seq raw data, and two sequences that contain SNPs were finally used to successfully identify three different cod product species, which are Atlantic cod (Gadus morhua), Greenland turbot (Reinhardtius hippoglossoides), and Patagonian toothfish (Dissostichus eleginoides). This SNP-based method will help us to identify the products, which are sold under the name of “Xue Yu” (Cod) in China, and works in parallel with existing fish identification techniques to establish an efficient framework to detect and prevent fraud at all points of the seafood supply chain.