Platinum sulfur poisoning

Figure 12. Transient HCN yield over platinum catalysts. A and B represent one experiment (Exp. 1) in which a sulfur-poisoned catalyst was regenerated on admission of 1% O2 into the inlet gas mixture between times t, and C shows the resistance of the catalyst to poisoning by SO when oxygen is simultaneously present in the inlet gas mixture. At t only oxygen is removed from the inlet gas mixture. (See Ref. 16 for details.)...

Platinum was found to be the most efficient hydrogenating component for the isomerization catalyst from the standpoint of amount required and resistance to sulfur poisoning. 

Zeolite-based hydrogenation catalysts containing platinum and palladium have increased resistance toward sulfur poisoning (101-104), and a higher activity (95, 105) than many other supports. In recent years there has been some effort devoted to attempt to explain this phenomenon. Although there is general agreement that the catalytic surface of the zeolites most probably... 

As in the case of Ni it appears that the effects of sulfur on the adsorption of organic molecules on other metals are more complex than for either H2 or CO. For example, formaldehyde (HCHO), which dissociates at 80 K on a clean Ru(110) surface (190), adsorbs molecularly on the sulfur-poisoned surface (78). Similarly, Cosyns et al. (191) suggest that sulfiding of the platinum enhances the adsorption of the alkylaromatics compounds. 

Catalytic reduction in the presence of platinum or palladium is a very mild method for splitting trityl ethers. The products are an alcohol and tritane. The latter may be separated from the alcohol by taking advantage of its solubility in petroleum ether. If the trityl ether contains sulfur, poisoning of the platinum or palladium catalyst may occur. ... 

The results of the sulfur poisoning, i.e. the difference in temperatures for achieving 10, 50 and 90 percent conversion of the different fuel components in the gas, H2, CO and CH4, are shown in fig 2. There are some clear trends that can be seen, the platinum catalysts (white bars) showed low deactivation (AT 0). This holds true for both the low temperature activity (i.e. H2 and CO combustion) and the high temperature activity (i.e. CH4 combustion). Palladium (stripy bars) showed a different behavior here the activity for CO and H2 remained more or less the same while the CH4 activity was greatly affected by the presence of SO2. For the Pd-YAG, the most affected catalyst, the temperature for 50 percent conversion for CH4 increased with as much as 250 °C, from 500 °C to 750 °C. For the metal oxides the picture is a little bit more complicated. For the MAS and LMA catalysts, the low temperature activities... 

Somorjai, G. A. On the mechanism of sulfur poisoning of platinum catalysts. Journal of Catalysis 11, 453-456 (1972). 

Deng YQ, Neved TG, Ewen RJ, Honeybonme CL, Jones MG (1993) Sulfur poisoning, recovery and related phenomena over supported padadium, rhodiinn and iridium catalysts for methane oxidation. Appl Catal A 101 51-62 Ehrhardt JJ, CoUn L, Jamois D (1997) Poisoning of platinum surfaces by hexamethyldisdoxane (HMDS) application to catalytic methane sensors. Sens Actuators B 40 117-124 Firth JG, Jones A, Jones TA (1973) The principles of the detection of flammable atmospheres by catalytic devices. Combust Flame 21 303-311... 

A 5% weight increase of the platinum/ceria catalyst was observed when exposed to sulfur dioxide and an excess of air at a 400 °C reaction temperature. Almost identical results were gained for a pure ceria carrier, which supports the assumption that ceria is extremely sensitive to sulfur poisoning. 

A higher tolerance to sulfur poisoning was observed for autothermal reforming of synthetic diesel fuel over bimetallic platinum/palladium and platinum/nickel catalysts compared with monometallic samples [257]. 

Platinum combustion catalysts are probably more tolerant to sulfur poisoning than palladium catalysts [350,355]. Corro et al. reported that sulfur dioxide may even have a promoting effect on propane oxidation [356]. They claimed that aluminium sulfate needs to be present on the catalyst surface to promote the reaction in the low temperature range below 300 °C. The sulfate formation was assumed to start at temperatures exceeding 500 °C. Therefore, the catalyst must have previously been exposed to such a temperature in the presence of sulfur dioxide. Over a pre-sulfated platinum/alumina catalyst, 50% methane conversion was achieved by 530 °C, while 560 °C was required for the sulfur-free counterpart [357]. However, no promotion effect is to be expected over non-sulfating carrier materials, such as sflica, according to Gelin and Primet [351]. 

G.A. Somorjai - On the Mechanism of Sulfur Poisoning of Platinum Catalysts,... 

A disadvantage of platinum/rhenium catalysts is their sensitivity to sulfur poisoning. This requires that naphtha feed must be carefully hydrotreated before use. 

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