Poison-resistant catalysts

G. R. Lester, andJ. C. Summers "Poison-Resistant Catalyst for Purification of Web Offset Press Exhaust," presented at Air Pollution Control... 

Poison-resistant Catalyst for Automotive Emission Control... 

Newly developed second-stage catalysts which increase their ability to resist either sulfur spikes in the second-stage feed or overall higher sulfur levels will greatly enhance the economics of the process. Criterion26 developed a more poison-resistant catalyst that in one plant extended the catalyst cycle length to 3.5 years from 6 months attained by the previous nickel catalyst. 

As in the case of homogeneous catalysis, poisons can also lead to deactivation of heterogeneous catalysts. Soluble or volatile metal or nitrogen compounds can destroy acid sites, while carbon monoxide and sulphur compounds almost invariably poison nickel and noble metal hydrogenation catalysts by bonding strongly with surface metal atoms. These considerations often lead to the selection of less active, but more poison-resistant, catalysts for industrial use. 

Fuel cells are developed as a viable alternative for clean energy generation. The rational operation of the fuel cell units is closely related to the development of very active, selective, and poison-resistant catalysts. 

When fuel contains heavier hydrocarbons than methane, or it is biofuel, or contains alcohols, the feedstock often contains additional compounds such as sulphur and phosphorus, that is, fertiliser impurities. In the petrochemical industry, gas-borne reactive spedes (i.e., sulphur, arsenic, chlorine, mercury, zinc, etc.) or unsaturated hydrocarbons (i.e., acetylene, ethylene, propylene and butylene) may act as contaminating agents (Deshmukh et al, 2007). These impurities cause catalyst deactivation by poisoning. The effect of a poison on an active surface is seen as site blockage or atomic surface structure transformation (Babita et a/., 2011). Therefore, it is important to choose poisoning-resistant catalyst materials. For example, nickel is not the most effective MSR catalyst although it is widely used in industry due to its low market price compared to ruthenium and rhodium. Both Ru and Rh are more effective in MSR and less carbon is formed in these systems, than in the case of Ni. However, due to the cost and availability of precious metals, these are not widely used in industrial applications. 

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