As concern grows over atmospheric pollution, government agencies worldwide have become focused on regulating the level of nitrogen oxide (NOx) emissions from oil refineries. NOx emissions from an FCC are extremely unit specific and can vary with changes in feed and other process parameters. Potential sources of NOx include nitrogen compounds from coke in the feed, nitrogen from air in CO boilers. Most of the nitrogen present in FCC feeds ends up in the coke being burned in the regenerator. When this is combusted the nitrogen forms N2, NOx and other nitrogen species depending on specific regenerator conditions, type of CO-promoters used, etc. Under full burn conditions NOx usually correlates well with flue gas excess oxygen, whereas under partial burn conditions much of the nitrogen in coke is only partially combusted to reduced species which go on to form NOx in the CO boiler.
Johnson Matthey’s INTERCATTMrange of NOXGETTER additives are tailored to capitalise on the inherent NOx emission gradients that exist in the regenerator. NOXGETTER has been proven to attain up to 50% reduction in NOx when used at up to 2 wt% in the catalyst inventory with reductions in NOx realised in less than 24 hours.
The latest development in NOx reduction is INTERCAT NONOX technology. This formulation focuses on selectively converting the precursors that go on to form NOx to N2. NONOX is also effective in partial burn regenerators because these precursors are present in abundance under partial burn conditions.