A model for a countercurrent gas—solid—solid trickle flow reactor for equilibrium reactions. The methanol synthesis

The theoretical background for a novel, countercurrent gas—solid—solid trickle flow reactor for equilibrium gas reactions is presented. A one-dimensional, steady-state reactor model is developed. The influence of the various process parameters on the reactor performance is discussed. The physical and chemical data used apply to the case of low-pressure methanol synthesis from CO and H2 with an amorphous silica—alumina as the product adsorbent. Complete reactant conversion is attainable in a single-pass operation, so that a recycle loop for the non-converted reactants is superfluous.\ud \ud In the following article the installation and experiments for which this theory was developed will be described

Gas-solid trickle flow hydrodynamics in a packed column

The pressure gradient and the static and the dynamic hold-up have been measured for a system consisting of a Fluid Cracking Catalyst (FCC) of 30–150 × 10−6 m diameter, trickling over a packed bed and with a gas streaming in countercurrent flow. The experiments were carried out at ambient conditions using a glass column of 25 × 10−3 m diameter. The packing material consisted of 8 × 8 × 3 mm ceramic Raschig rings, a mixture of 7 × 7 × 1 mm glass Raschig rings and 5 × 5 mm catalyst pellets and of stacked Kerapak ceramic mixing units of Sulzer, each unit 50 mm long and 25 mm in diameter. Four different gases have been tested. A correlation for the pressure gradient in the preloading region is derived based on the Ergun equation and taking into account the internal gas recirculation due to the solids trickles. The void fraction of the trickles is found to be independent of the physical properties of the gas phase. The behaviour of the GSTF-system in the preloading regime and the phenomena of loading and flooding are discussed. A correlation is given which relates the boundary between preloading and loading with the particle and gas properties and the solids flow rate

Binary vapour—liquid equilibria of methanol with sulfolane. Tetraethylene glycol dimethyl ether and 18-crown-6 = Phasengleichgewichte in binären systemen von Methanol mit Sulfolan, Tetraethylenglycoldimethylether und 18-krone-6 Kronenether

The activity coefficients of methanol in sulfolane, tetraethylene glycol dimethyl ether (TEGDME) and 18-crown-6 under conditions of equilibrium have been determined in the temperature range 423–503 K and in the pressure range 0.28–3.5 MPa. A minimum in the activity coefficient was found for the methanol—TEGDME and methanol—18-crown-6 solutions

The kinetics of the methanol synthesis on a copper catalyst: An experimental study

The kinetics of the low pressure of methanol from feed gases containing solely CO and H2 were studied in an internally recycled gradientless reactor. As experimental accuracy impeded the application of high CO contents, the experimental range of mole fraction of CO was limited to 0.04 to 0.22. The total pressure was varied from 3 to 7 MPa and the temperature from 503 to 553 K. Residence time distribution experiments confirmed the assumption of perfect mixing on a macroscale. A maximum likelihood approach was used to fit possible kinetic equations. Although more accurate results and better fits—compared to previous experiments in a simple integral reactor—were obtained, no single rate expression could be selected as the most appropriate one. This was mainly attributed to the effects of small amounts of CO2 and H2O formed in the reactor. Three different reaction rate equations fit the experiments equally well. Arguments are given that we never can expect to elucidate the reaction mechanisms on the basis of kinetic experiments

Simultaneous dehydrogenation of organic compounds and hydrogen removal by hydride forming alloys

The applicability of hydrogen-absorbing metals in dehydrogenation reactions was investigated. Based on thermodynamic considerations, operating ranges were defined within which an increase of the reactant c onversion can be achieved owing to an in situ hydrogen removal by the alloy. Low plateau pressures (e.g. < 0.01 MPa) at high temperature (e.g. > 473 K) are required for economic applications. An (economic) improvement of the alkane-to-alkene conversion does not seem feasible owing to the extreme pressure and temperature conditions. In the present study as a model system, 2-propanol was dehydrogenated in a batch process at 473 K and 0.1-1.0 MPa over a Cu/CuO catalyst in the presence of an excess amount of Mg2.4Ni. The hydride forming metal alloy appears to be able to affect the hydrogen balance of the experimental system owing to absorption or desorption. However, an unexpected catalytic effect of the metal hydride was observed towards condensation reactions. Owing to the loss in selectivity, Mg2.4Ni, is not applicable for an improvement of the dehydrogenation processes for secondary alcohols

Reaction kinetics for the synthesis of methanol from CO and H2 on a copper catalyst = Reaktionskinetik der methanolsynthese aus CO und H2 auf einem kupferkatalysator

The kinetics for the low-pressure synthesis of methanol from CO and H2 were studied in a small integral reactor. The mole fraction of CO was varied from 0.1 to 0.54, the total pressure from 3 to 9 MPa and the temperature from 483 to 545 K.\ud \ud Using the maximum likelihood approach, seventeen possible reaction rate correlations were evaluated statistically. Among these models three appear to fit the experimental data satisfactorily

Open World Assistive Grasping Using Laser Selection

Many people with motor disabilities are unable to complete activities of daily living (ADLs) without assistance. This paper describes a complete robotic system developed to provide mobile grasping assistance for ADLs. The system is comprised of a robot arm from a Rethink Robotics Baxter robot mounted to an assistive mobility device, a control system for that arm, and a user interface with a variety of access methods for selecting desired objects. The system uses grasp detection to allow previously unseen objects to be picked up by the system. The grasp detection algorithms also allow for objects to be grasped in cluttered environments. We evaluate our system in a number of experiments on a large variety of objects. Overall, we achieve an object selection success rate of 88% and a grasp detection success rate of 90% in a non-mobile scenario, and success rates of 89% and 72% in a mobile scenario

Food Characterization of the Spotted Pimelodid Fish Pimelodus Maculatus From a Polluted Urban River in Argentina

On the present study, the nourishment and the digestive system of a population of the spotted pimelodid Pimelodus maculatus Lacepède 1803 from a polluted urban river in Argentina were analyzed (Reconquista River, Buenos Aires province). The specimens are characterized by having benthic habits and an omnivore diet. In their intestinal content, a diversity of components was identified. Such components were grouped into ten alimentary items, with dietary variations according to body size while the longitude of the intestine remained proportional to standard length. Microbiological analysis in the gills, stomach and intestine showed the occurrence of Staphylococcus aureus, Escherichia coli and Salmonella sp. Fungi and yeast were also detected. Bacterial accounts were very high both in the analyzed organs as well in water samples. The ecological and sanitary significance of the identified bacteria is discussed

Induced Anticlinic Ordering and Nanophase Segregation of Bow-Shaped Molecules in a Smectic Solvent

Recent experiments indicate that doping low concentrations of bent-core molecules into calamitic smectic solvents can induce anticlinic and biaxial smectic phases. We have carried out Monte Carlo (MC) simulations of mixtures of rodlike molecules (hard spherocylinders with length/breadth ratio $L_{\rm rod}/D = 5$) and bow- or banana-shaped molecules (hard spherocylinder dimers with length/breadth ratio $L_{ban}/D = 5$ or 2.5 and opening angle $\psi$) to probe the molecular-scale organization and phase behavior of rod/banana mixtures. We find that a low concentration (3%) of $L_{ban}/D = 5$ dimers induces anticlinic (SmC$_A$) ordering in an untilted smectic (SmA) phase for $100^\circ \le \psi < 150^\circ$. For smaller $\psi$, half of each bow-shaped molecule is nanophase segregated between smectic layers, and the smectic layers are untilted. For $L_{ban}/D = 2.5$, no tilted phases are induced. However, with decreasing $\psi$ we observe a sharp transition from {\sl intralamellar} nanophase segregation (bow-shaped molecules segregated within smectic layers) to {\sl interlamellar} nanophase segregation (bow-shaped molecules concentrated between smectic layers) near $\psi = 130^\circ$. These results demonstrate that purely entropic effects can lead to surprisingly complex behavior in rod/banana mixtures.Comment: 5 pages Revtex, 7 postscript figure

Transkingdom Networks: A Systems Biology Approach to Identify Causal Members of Host-Microbiota Interactions

Improvements in sequencing technologies and reduced experimental costs have resulted in a vast number of studies generating high-throughput data. Although the number of methods to analyze these "omics" data has also increased, computational complexity and lack of documentation hinder researchers from analyzing their high-throughput data to its true potential. In this chapter we detail our data-driven, transkingdom network (TransNet) analysis protocol to integrate and interrogate multi-omics data. This systems biology approach has allowed us to successfully identify important causal relationships between different taxonomic kingdoms (e.g. mammals and microbes) using diverse types of data