Preparation steam reforming catalysts

The alkali free catalyst used in this study was a commercial nickel oxide/ -alumina steam reforming catalyst. The total nickel content of the catalyst was 10 % w/w. An alkali promoted catalyst was prepared by dipping the nickel oxide/< -alumina catalyst in a 12% v/v potassium hydroxide solution and then drying the catalyst, at lOD C, for a period of 16 hours The... 

F. Basile, P. Benito, P. Del Gallo, G. Fomasari, D. Gary, V. Rosetti, E. Scavetta, D. Tonelh, A. Vaccari, 2008, Highly conductive Ni steam reforming catalysts prepared by electrodeposition, Chem. Commun. 2008,2917-2919. 

The reaction shown above for the steam reforming of methatie led to die formation of a mixture of CO and H2, die so-called synthesis gas. The mixture was given this name since it can be used for the preparation of a large number of organic species with the use of an appropriate catalyst. The simplest example of this is the coupling reaction in which medrane is converted to ethane. The process occurs by the dissociative adsorption of methane on the catalyst, followed by the coupling of two methyl radicals to form ethane, which is then desorbed into the gas phase. 

Figure 8.3.1 is a typical process diagram for tlie production of ammonia by steam reforming. Tlie first step in tlie preparation of tlie synthesis gas is desulfurization of the hydrocarbon feed. Tliis is necessary because sulfur poisons tlie nickel catalyst (albeit reversibly) in tlie reformers, even at very low concentrations. Steam reforming of hydrocarbon feedstock is carried out in tlie priiiiiiry and secondary reformers. 

Ethanol and methane steam reforming reactions were studied assuming that the exit composition of the ethanol reformer depends on the steam reforming of methane. The competition for the same active site for ethanol and methane reforming maximizes the H2 and C02 production and minimizes the CO formation Catalysts were prepared by incipient wet impregnation. 20 wt% Ni supported on ZnO exhibited better performance compared to that supported on La203, MgO and A1203... 

Catalysts were prepared by incipient wetness impregnation of commercial supports using cobalt nitrate as a precursor. Metallic cobalt species were active centers in the ethanol steam reforming. Over 90% EtOH conversion achieved. Nature of support influences the type of byproduct formation. Ethylene, methane and CO are formed over Co supported on A1203, Si02 and MgO, respectively... 

Cobalt-based catalysts are effective in the ethanol reformation to hydrogen. Many oxides have been used to prepare supported cobalt catalysts of low cobalt content (circa 1 wt%) by impregnation from a solution of Co2(CO)8 catalysts were used in the ethanol reformation as prepared [156]. The performance of the catalysts in the steam reforming of ethanol was related with the presence, under reaction conditions, of metallic (ferromagnetic) cobalt particles and oxidized cobalt species. An easy exchange between small metallic cobalt particles and oxidized cobalt species was found. Comparison of Co/ZnO catalysts prepared from Co2(CO)8 or from nitrate precursor indicated that the catalyst prepared from the carbonyl precursor was highly stable and more selective for the production of CO-free hydrogen... 

In a later study, Pfeifer et al. [30] prepared Pd/Zn catalysts by both pre- and postimpregnation of wash-coated zinc oxide particles with palladium and compared their performance in methanol steam reforming. The catalytic performance of the samples was tested at a 250 °C reaction temperature, 3 bar pressure, a S/C ratio of two and 250 ms residence time. The WHSV amounted as 0.3 Ndm3 (min gcat) 1. The thickness of the coatings was calculated to 20 pm. The formation of the PdZn alloy was proven to occur at temperatures exceeding 200 °C by XRD measurements. 

A total of206 mg [119] of commercial Cu/Zn catalyst from SiidChemie (G-66MR) ground to the nanometer range was coated into the channel system at 5 pm thickness to promote the steam reforming reaction. A cobalt oxide catalyst was prepared by impregnating the corundum layer (see above) with cobalt nitrate and calcining at 350 °C for 2 h 434 mg [119] of the CoO catalyst were applied for the combustion reaction (see Section 2.5). 

Wash coats made of various source aluminas were prepared by applying this procedure (Figure 2.96) [147]. The catalysts obtained after subsequent impregnation were applied to methanol steam reforming [25, 28], propane steam reforming [52], water-gas shift [84] and preferential oxidation [89], to name but a few reaction systems. 

Chin, Y.-H., Wang, Y., Dagle, R. A., Li, X. S., Methanol steam reforming over Pd/ZnO catalyst preparation and pretreatment studies, Fuel Process. 

Banks, Paterson, and Williams of British Gas have described951 the preparation and properties of a coprecipitated Ni-Al203 catalyst (50 wt% Ni) to which were added 1.0 wt% of an alkali metal and 0.5 wt% of ruthenium. This material was shown to have desirable properties when used for the steam reforming of a hydrocarbon oil in the temperature range 410-476 °C. It is, however, not very likely that such a catalyst will be used commercially because of the high cost of ruthenium and the limited supplies of this metal which are available. Another British Gas patent, referred to previously, introduces chromium into the formulation to improve the stability of the resultant catalyst.77... 

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