Monolithic catalysts impregnation

In this study, a novel Monolith alumina structure was of interest as a base (or a carrier) material for Co-Mo-Alumina catalysts. The specific interest centered around assessing the suitability of the catalyst prepared by impregnating the novel alumina support with Co and Mo for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) of a relatively high boiling stock. The Monolith catalyst was also tested on a low boiling coal-derived liquid. 

Catalysts. The properties of the two catalysts used in this study are given in Table II. The Monolith catalyst was prepared in the laboratory at OSU by impregnating Co and Mo on the Monolith alumina support received from the Coming Glass Company. The Nalcomo 474 catalyst was received from the Nalco Chemical Company and is a commercial preparation used as a reference catalyst in this study. 

Membranes that arc catalytically active or impregnated with catalyst do not suffer from any potential catalyst loss or attrition as much as other membrane reactor configurations. This and the above advantage have the implication that the former requires a lower catalyst concentration per unit volume than the latter. It should be mentioned that the catalyst concentration per unit volume can be further increased by selecting a high "packing density" (surface area per unit volume) membrane element such as a honeycomb monolith or hollow fiber shape. 

Impregnation is one of the most used techniques to incorporate an active phase in a support. It can also be used to deposit active phase to a monolith [85]. Usually, a high-surface-area monolith is dried, evacuated, and dipped in a solution containing a precursor of the active phase. After drying and calcination a monolithic catalyst is obtained. Often, an activation step is necessary to convert the precursor of the active phase into the active phase, e.g., the transformation of a metal oxide in the corresponding metal or metal sulfide. Monolithic catalysts with complex compositions of active phases can be prepared by sequential impregnations with suitable solutions or with a conunon solution containing various precursors of the components. 

A 400 cpi cordieiite monolith is coated with a polymer made from the polymerization of furfuryl alcohol. The coated cordierite is then heat treated (calcination), and after an activation step the active metal, Pd, is impregnated followed by another heat treatment. One characteristic of the monolith catalyst made this way is its low surface area (13). The hydrogenation of nitrobenzene is used to probe the activity of the monolith catalyst. Table 10 summarizes these results for a series of monolith catalysts. 

The aim of this research project is the design and synthesis of optimal monolithic reactors and its use in deep desulfurization. In order to do so, state-of-the-art HDS powder catalysts were first prepared and their activity in thiophene HDS compared to the monolithic catalysts. These monolithic catalysts were prepared from cordierite and coated first with two layers of a-AI2O3 followed by one layer of Y-AI2O3. The coated monoliths were then impregnated with NiMo solutions (optimized for the powder catalysts) and some parameters were optimized (such as impregnation time and drying procedure). Finally, monolithic catalysts with the same characteristics as powder catalysts were obtained. 

A Pd-Pt catalyst was prepared by successive impregnations of mono 2 with the metal precursors, Pd(N03)2.2H20 (in water solution at room temperature) and Pt(acetylacetonate)2 (in toluene at 70 °C), respectively. After each deposition, the monolithic catalyst was dried at 120 °C and calcined at 400 °C for 2h. The finished sample (PdPt/mono 2) contains Pd-Pt in atomic ratio 1 1 and total loading of 0.2 wt% of the monolith weight, corresponding to an... 

Laboratory tests were made of catalysts prepared on spherical alumina supports and on monolithic catalysts. The spherical catalysts were prepared by a proprietary technique, and were protected against shrinkage by use of a chemical stabilizer. The monoliths were wash-coated with alumina prior to impregnation with the metals. The catalysts were tested fresh and also after thermal treatment (10 hrs at 1094°C in a perfluent atmosphere consisting of 10% H20 in air). 

The catalyst was prepared on a cordierite monolith having 62 cells per cm2, xhe support was coated with a promoted alumina-ceria (6 % Ce02) wash-coat and impregnated with 1.06 g/1 of platinum plus rhodium, with a Pt/Rli mass ratio of 5. After impregnation, the catalyst was calcined for 2 hours at 500°C. Activity measurement... 

Vergunst, T., F. Kapteijn, and J.A. Moulijn, Monolithic catalysts Non-uniform active phase distribution by impregnation. Applied Catalysis A General, 213 pp. 179-187, 2001. 

The impregnation is performed generally from an aqueous solution of known concentration of the metal precursor. The procedure is to immerse overnight the coated monoliths into the precursor solution under mechanical agitation. The excess of the solution is then evaporated. When the precursor solution is completely evaporated, the impregnated monoliths are carefully dried before thermal treatment. This is carried out in a lab-made quartz reactor adapted to the size of the monolithic catalysts (Figure 8-c and d). For platinum, rhodium and iridium active phases, this treatment corresponds to a reduction under hydrogen flow diluted in helium. 

The SCR catalyst designed for FCCU regenerator flue gas service is a homogenous monolith, typically made from 1 mm thick material. Some catalysts are extruded clays that receive a wash coat of titanium dioxide before impregnation of the vanadium and tungsten metals. Another type involves painted plates of expanded metal... 

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