Traps metal

At high metals levels, the coking characteristics of a cracking catalyst can be greatly increased that is, the ratio of contaminant coke to catalytic coke can be quite high. The effect of the contaminant metals on the coke response is affected not only by the level of metals but also by the type of catalyst and the use of a metals passivator. Catalysts, which contain effective metals traps to inhibit the contaminant effects, do produce much less contaminant coke than catalyst without metal traps. 

During the 1980s, antimony was widely used in FCCUs that had a problem with contaminant metals. In the late 1980s, other additives were introduced to combat the contaminant metals, eg. Chevron introduced a bismuth-based additive, which is claimed to provide performance similar to antimony (18). Also in the late 1980s, cracking catalysts were developed with metals traps that appear to be so effective in containing the adverse effects of contaminant metals that additive-type inhibitors are no longer needed (19). 

Extremely shock-sensitive and violently explosive initiation has been caused by prolonged freezing at —196°C, or by sawing a stopcock off a metal trap containing trace amounts [1], It may be stored safely at — 80°C [2], Detonative explosion during trap-to-trap distillation of purified material is noted [3],... 

Dining interaction at ambient temperature in a bomb to produce poly (carbon monofluoride), admission of fluorine beyond a pressure of 13.6 bar must be extremely slow and carefully controlled to avoid a violently exothermic explosion [1], Previously it had been shown that explosive interaction of carbon and fluorine was due to the formation and decomposition of the graphite intercalation compound, poly (carbon monofluoride) [2], Presence of mercury compounds prevents explosion during interaction of charcoal and fluorine [3], Reaction of surplus fluorine with graphite or carbon pellets was formerly used as a disposal method, but is no longer recommended. Violent reactions observed when an exhausted trap was opened usually involved external impact on the metal trap, prodding the trap contents to empty the trap, or possibly ingress of moist air... 

Sturgeon et al. [398] applied in situ metal trapping to the determination of lead in seawater. 

To extend the levels of detection for mercury stiU lower, several workers, especially in this area of atomic absorption techniques, have chosen to collect the mercury on gold or other noble metal trapping systems prior to revaporizing the mercury into the measurement technique. Figure 7.14 shows the configuration of a specific system to concentrate mercury onto an amalgam preconcentrator prior to analysis. 

SO removal Combustion promotion Octane enhancement Metal traps/passivators Bottoms cracking... 

Several catalysts on the market today contain special vanadium traps or vanadium scavengers in order to protect the active ingredients against poisoning and/or destruction by Vanadium. These "Metal Traps" limit the mobility of the vanadium pentoxide compounds under FCC conditions (2, 10). The nickel problem needs to be approached differently and more recently, progress has been made towards reducing the dehydrogenation activity of nickel dispersed on FCC catalysts (11). 

FCC catalyst development to reduce the effect of vanadium has been aimed at reduction of vanadium mobility the application of special ingredients in the catalyst which function as metal scavengers or metal catchers. In the past (2, 10) transport experiments were used to show that during steam-aging, intraparticle transfer of vanadium occurs and that migrating vanadium can be irreversibly sorbed by a metal trap such as sepiolite (2) in the form of a heat stable vanadate. 

In FCC units which exhibit a high tendency to vanadium migration, the application of metal traps can be very beneficial. 

LCMR Minimum mesopore activity with MR metal trap ES High mesopore activity with ADVANCE technology... 

From the foregoing chapters it should be clear that the development of a successful FCC resid catalyst depends on several aspects the relative priorities of which will be determined by the refinery objectives, feedstock, FCC unit configuration and limitations. Still, it is worthwhile to distinguish certain "idealized objectives" in order to focus the catalyst development in this field. The advances in resid FCC catalyst development up to now have been mainly in the field of metal tolerance (metal traps), while also progress has... 

Aqua regia extraction is a strong partial extraction method that dissolves carbonates, most sulphide minerals, some silicates like olivine and trioctahedral micas, clay minerals and primary and secondary salts and hydroxides (Salminen, 1995). It can be considered a quasi-total extraction method, since actual total concentrations can be higher. On the other hand, this leaching method overestimates the bioavailable amount of toxic elements in a soil since metals trapped in the silicate lattice are released very slowly in the environment and are not easily involved in plant nutrition processes. 

Under actual FCC conditions, the penetration and age profile of the metals will influence the efficiency of the catalyst metal trapping function [23,39,40] and consequently catalyst activity and selectivity. 

Rare Earth Metals Trapped Inside Fullerenes - Endohedral Metallofullerenes (EMFs)... 

Rare Earth Metals Trapped Inside Fullerenes... 

A simplified cyclic test (Mitchell method followed by cyclic propylene steaming) has been proposed which addresses the redox aging of the metal, but not the non-uniform laydown and age distribution of metals on the catalyst. Under actual FCC conditions, the penetration and age profile of the metals will influence the efficiency of the catalyst metal trapping function [23,39,40] and consequently catalyst activity and selectivity. 

An autocatalyst must be obtained from some external reservoir by expenditures of matter (which especially in terrestrial plants may be quite substantial when secreting chelators to the rhizosphere for subsequent retrieval after metal trapping). 

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