KDNOx 2001

The air quality in many cities around the world has also been a hot topic in the past years. Atmospheric studies have shown that exhaust emissions contribute to a complex series of chemical reactions, driven by sunlight that leads to the formation of ozone. These studies indicate that in many cases, reducing NOx emission is the only solution to reducing ozone levels.

Refiners had to deal with oxides of carbon and oxides of sulfur, so it was inevitable that sooner or later they would have to address oxides of nitrogen. Although NOx emissions from stationary sources such as FCC units comprise a very small percentage of the total, refiners are subject to regulations because these emissions are concentrated locally, often in or close to so-called "ozone non-attainment areas."

While new regulations represent just one more problem for today’s refiner, they present a significant challenge to catalyst companies since the chemistry associated with reducing oxides of nitrogen is distinctly opposite to the approach employed in reducing the oxides of carbon and sulfur. Additive design for the latter involves direct oxidation of CO to the relatively harmless CO2 and oxidation of SO2 to SO3 with subsequent adsorption. In the case of nitrogen, roughly half the nitrogen in the feed ends up in coke. Studies indicate that part of this nitrogen is converted to HCN and NH3, with subsequent oxidation in the regenerator to NO and NO2. Somewhere between 5 and 15% of the nitrogen in the coke ends up as NOx.

Albemarle’s approach to reducing NOx is twofold. First, in the event that a conventional platinum CO combustion promoter is present and aggravating the situation (by virtue of oxidizing NH3 and HCN to NOx), we are able to offer ELIMINOx, an alternative non-platinum, bimetallic CO combustion promoter. Secondly, we have developed KDNOx-2001. KDNOx is a second-generation additive that functions by selective adsorption of NOx, with subsequent reduction to inert nitrogen gas.