Catalysts sodium content

Sodium Content. The sodium on the catalyst originates either from zeolite during its manufacture or from the FCC feedstock. It is important for the fresh zeolite to contain very low amounts of sodium. 

FCC catalyst vendors are now able to manufacture catalysts with a sodium content of less than 0.20 wt%. Sodium is commonly reported as... 

The increase in octane observed using dealuminated faujasite compared to high cell size rare earth exchanged faujasite has been correlated with the Si/AI ratio of the sieve and with the sodium content (3). While the relationship between Si/Al ratio as measured by unit cell is confirmed by pilot unit studies in our laboratory. Figure 1, the relationship with sodium content is more complicated. Figure 2. Sodium added to the catalyst after hydrothermal dealumination reduces activity but does not affect octane, while sodium present before hydrothermal dealumination increases activity but does reduce octane. This result implies that selectivity for octane is related to structures formed during... 

Entry Phenol (ppw) Sodium Sulfite (ppw in water) 50% Formaldehyde (ppw) Water (ppw) Co-catalyst Tetradimer Content (ppw)... 

Laboratory investigation revealed that sodium, which was present in the support to the extent of several tenths of 1%, had a profound effect on stability and activity of the moiybdena-alumina catalyst. Over a period of time it was possible to alter the procedure for preparing the support on successive occasions until the catalyst contained much less than 0.1% sodium oxide. The reduction in sodium content of the support was immediately reflected in improved catalyst life. Ultimately the life was extended to 9 to 12 months before replacement. Various forms of alumina have been used as a support, including alumina gel and a stabilized alumina gel. Moiybdena-alumina catalyst has been employed exclusively in the eight commercial plants previously referred to. Today the majority of refiners who operate hydroformers are using molybdena on alumina gel as a catalyst. The molybdic oxide content of the catalyst is somewhat below 10%. Although similar to the original catalyst as far as chemical composition is concerned, it possesses superior activity and life. 

Fig. 12. Dependence of apparent rate coefficient, k (sec-1), on sodium content, mNa (mol Na per 100 g cat), in silica gel catalysts for the vapour phase condensation of formaldehyde with (1) acetaldehyde, (2) acetone, (3) acetonitrile, at 275°C [372].

In the sequence of catalyst samples 1, 4, and 5, there is both an increase in effective diffusivity and a decrease in sodium content. Both factors operate in the same direction, and it is not possible to say whether the increase in initial activity (i.e., k0) is caused more by an improved physical situation or by decreased chemical poisoning. In the sequence of samples 1, 2, and 3, the decreased number of active sites plays the predominant role the initial activity drops sharply in spite of the higher diffusivity. 

It was noted that sodium hydroxide-precipitated catalysts were quite active in contrast with comparatively inactive ammonia-precipitated catalysts. Investigation of a series of catalysts with varying sodium content proved that the sodium content of a chromium oxide catalyst has a... 

Fe-Cu-Na catalysts were prepared by coprecipitation from the iron and copper nitrates with sodium hydroxide. Sodium contents were controlled by washing the precipitates. The composite catalysts were obtained by physical mixing of equal amounts of Fe-Cu-Na oxides and zeolites. After reducing the samples in a flow of 10% H2/N2 for 6 h at 350°C, the catalysts were kept at 250°C in a flow of reaction gas under 20 atm. The reactants and products were analyzed with an online gas chromatograph system. The XRD powder patterns of the catalysts before and after the reaction were obtained with C xKa radiation at 40 kV and 30 mA on a RIGAKU X-ray diffractometer. 

Various solids consisting of magnesium and sodium-magnesium mixed orthophosphates were synthesized and used as catalysts in the transformation of 2-hexanol. The solids obtained were characterized by using various elucidation techniques. In particular, acid-base properties were determined by several methods. The solids were found to be active in the dehydration and dehydrogenation of the alcohol studied, and to be highly selective towards the dehydrogenation product in some instances. In addition to surface properties, the structure and composition of the catalysts -particularly their sodium content- appear to play essential roles in their catalytic behaviour. 

Zeolites were selected for these studies because they possessed the types of properties (high crystallinity, low sodium content, and wide range of silica/alumina ratio) generally valued in catalyst development work All were commercial (not developmental) products of either the Linde Division of Union Carbide Corporation (Danbury, Connecticut) or Conteka, B.V. (Surte, Sweden). 

While the work described in this paper was originally intended to address Chevron Research Company s specialized needs in its role as a catalyst developer, manufacturer, and licensor several generally significant results were obtained. First, it is apparent that HDY s are now available with a very wide range of chemical and physical properties. While come may appear to be particularly well suited to a specific application, e.g., one where very high acidity (very low sodium content is desired, it is very clear that they may be extremely susceptible to structure loss in media commonly used in catalyst manufacturing. On thiB basis, chemical stability screening should certainly become a routine part of catalyst development work. 

In order to test our deposition-precipitation method, we have prepared gold on titania P25 (Table 1, entry 4) and compared it to a Au/P25 reference catalyst (Table 1, entry 5). It turns out that the average gold particle sizes and the size distributions are similar, around 3.7 1.5 nm. However, the gold loading as well as the sodium content are smaller in our case (by 2.3 and 3.9 times respectively), probably due to the extensive washing procedure that we have applied. This indicates that the interaction between the gold precursor and the support is still quite weak after 18 h reaction at 20°C. After treatment under reaction conditions, these two materials display similar rates both in the oxidation of CO under PROX conditions and in the oxidation of H2. However,... 

Recently, Diaz-Mendoza et al. (1998) have studied the catalytic behaviour and the catalyst decay of Beta, RY and USY zeolites. They propose that Lewis acid sites promote the formation of unsaturated compounds (favoring coke formation). However, Bronsted acid sites with intermediate acid strength appear to be appropiate sites for maintaining good alkylation catalytic performance. They observe that the best catalytic performance and the slowest deactivation were achieved with Beta zeolite, followed by RY and USY with low sodium content. However, only butene isomerization was observed over USY zeolite with high sodium content. 

Each experiment was performed using 1.0 0.2 g of the catalyst designated as H-22, undiluted. This is the H form of a ZSM-5 sample prepared by the procedure described as method B by GABELICA et al ( ). It has Si/Al ratio of 22, and its sodium content is less than 220 pxxn as determined by PIXGE (29). 

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