Catalyst powder injection

Both approaches were actually using the characteristics of the laminar flow in micro structures, which enable a defined deposition of catalysts as the characteristics of the laminar flow remain unchanged. The deposition is not affected by unforeseeable turbulent effects. The reactors were used for catalyst preparation and for catalyst testing simultaneously. 

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For the modification of a 4-mm MAS NMR probe, an injection tube with an outer diameter of 1 mm is used, and the hole in the rotor cap has an inner diameter of 1.4 mm. This 4-mm CF MAS NMR probe reaches sample spinning frequencies of 12 kHz and is suitable for the investigations of atoms in the framework of solid catalysts, such as Na, Al, and nuclei. Approximately 50 mg of catalyst powder can fit in the rotor reactor of a 4-mm CF MAS NMR probe. 

Gas-phase processes commercialized in the late 1960s offer much simpler operation. Since they eliminate solvent, solvent separation, recovery, and purification are unnecessary. Polymerization is carried out in stirred-vessel reactors or in fluidized beds. A very successful fluidized-bed process is Union Carbide s UNIPOL technology444 designed originally for producing HDPE and extended later to LLDPE. Ethylene is polymerized by injecting the fine catalyst powder (organotitanium or... 

In CF MAS NMR investigations of adsorbate complexes and reactants, modified 7-mm MAS NMR probes are used. The injection tube has an outer diameter of 1.5 mm, and the hole in the rotor cap has an inner diameter of 2.5 mm. The maximum sample spinning frequency of 7-mm CF MAS NMR probes is ca. 3.5kFfz. Approximately 200 mg of catalyst powder fits in the rotor reactors of a 7-mm CF MAS NMR probe (60). 

In Figure 23—6, polymer grade ethylene and any comonomers are blown into the-base of a fluidized bed reacton A very reactive catalyst (based on-titanium and magnesium chlorides) is injected and admixes with the ethylene. Polymerization takes place at 150-212 F and 300 psi, and polymer particles stay in the fluidized state as the ethylene swirls through the reactor. Since the temperature is controlled at or below the melting point, the particles form a white powder. 

Tronconi et al. [46] developed a fully transient two-phase 1D + 1D mathematical model of an SCR honeycomb monolith reactor, where the intrinsic kinetics determined over the powdered SCR catalyst were incorporated, and which also accounts for intra-porous diffusion within the catalyst substrate. Accordingly, the model is able to simulate both coated and bulk extruded catalysts. The model was validated successfully against laboratory data obtained over SCR monolith catalyst samples during transients associated with start-up (ammonia injection), shut-down (ammonia... 

A mechanistic study of butene isomerization was carried out using i C labelled butene, >3CH2=CH-CH2-CH3 and a GC-MS set up. The GC injector was equipped with a narrow glass tube containing 20 mg of powdered FER catalyst. In a typical experiment a butene sample (1 1, 0.9 bar) is injected, the products are separated by GC and then individually analyzed by mass spectrometry (MS) (Kratos Concept). Fresh and spent (but still active for butene isomerization) HS-FER was used for these experiments. Experiments were carried out at a catalyst temperature of 350°C. 

For the experimental standard procedure 15.0 g a-pinene oxide was stirred in 30.0 g of toluene, brought to reaction temperature in a flask equipped with a double wall cooling system and mixed with 2.0 g of powdered catalyst under careful temperature control Product samples were taken from reaction mixture by means of a syringe filter and analyzed by gas chromatography. The analysis was performed on a Siemens RGC 202 using a 60 m capillary column SE 54. The injection temperature was 200°C Products were identified by GC-MS or by comparing them with authentic samples. 

A pentaerythritol-based dendrimer modified with bis-terpyridyl Ru(II) was shown to be effective as a catalyst for the electrochemical oxidation of methionine (L-Met) and cystine (L-Cys) in aqueous solution or the mixed solvent AN-water (12% AN) [100]. In this case, the dendrimer was mixed with carhon powder and, using a sol-gel hinder, the carhon electrode doped with the [Ru(tpy)2] " -functionalized dendrimer was prepared. The oxidation peak of [Ru(tpy)2] was enhanced by the addition of L-Met, indicating the electro-catalytic effect of the dendrimer. Using the composite electrode doped with the dendrimer as an amperometric detector for flow-injection analysis, a linear calibration curve was obtained over the range 1-lOpM of L-Met in phosphate buffer (pH 7.0). A similar cahbration curve was obtained for L-Cys over the range 1-10 pM in phosphate buffer (pH 2.3). 

The model of Reference (116) was also compared to laboratory data obtained over two commercial SCR high dust monolith catalysts during transients associated with start-up (NH3 injection), shutdown (NH3 shutdown), and step changes of the feed composition at different temperatures and NH3/NO molar feed ratios. Figure 16 compares some of such data with model predictions. To achieve the agreement shown in the figure, the kinetic parameters had to be slightly modified with respect to those determined over the model catalyst in powder form. 

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