NO Reduction Studies in the FCC Process. Evaluation of NO Reduction Additives for FCCU in Bench- and Pilot Plant-Scale Reactors

Abstract

During FCC catalyst regeneration, part of the nitrogen in coke forms NO x , which makes up a significant part of the total NO x refinery emissions. The addition of a small percentage (e1 wt %) of catalytic additive(s) in the FCC inventory can reduce the NO x emissions from the flue gases of the FCC regenerator. In this paper, experimental techniques are considered for evaluating, in laboratory reactors, the performance of two commercially available NO x removal additives. It has been shown that in an FCC regenerator the gas residence time and the concentration of CO in the flue gases are key parameters in controlling NO x emissions. For example, pilot plant experiments showed that the addition of a CO oxidation promoter (CP-3) in the catalytic inventory decreases the CO emissions significantly and increases the NO x emissions about 4 times. Replacement of the active CO oxidation promoter (CP-3) with an additive (XNO x ) with moderate CO oxidation activity reduced the NO x emissions by 78%. Comparison of regeneration results performed in bench-scale reactors with those measured in our FCC pilot plant unit showed that it is possible to evaluate NO x reduction additives in bench-scale experiments. The proposed protocol for this evaluation is to mix spent FCC catalyst with the NO x reduction additive and to load this mixture in a fluidized bed reactor. The above mixture is then regenerated at 700 °C by 2% O 2 diluted in N 2 .

Effect of Ru-Based Catalytic Additives on NO and CO Formed during Regeneration of Spent FCC Catalyst

“…Bench-Scale Evaluation. In our previous work, , we presented regeneration experiments of either unpromoted spent FCC catalyst or a mechanical mixture of the same unpromoted spent FCC catalyst with a commercial, Pt-based CO promoter (CP-3). The presence of a conventional CO promoter (CP-3) in the catalytic inventory decreased the CO emissions by approximately 1 order of magnitude, but almost tripled the NO emissions. , As already mentioned, the presence of 1% CP-3 mixed with spent catalyst will be considered as the base case, used to evaluate additive's performance both for NO and for CO conversion.…”

“…As previously mentioned, the FCC pilot plant sufficiently simulates the operation of industrial FCC units. Moreover, a comparison between evaluation of commercial additives in the pilot plant and the bench-scale unit was used to determine a standard evaluation protocol of candidate materials in bench scale . Thus, for a more complete evaluation of the catalytic performance of Ru-based additives under realistic conditions, we decided to examine their efficiency for the simultaneous reduction of NO and CO emissions during regeneration in the pilot plant FCC unit.…”

“…The unit consists of the feed gas system, a fluidized-bed reactor, and the gas analysis system. A detailed description of this unit can be found in previous reports . The total flow rate was 1000 cm 3 /min, while the feed composition was 2% O 2 in N 2 .…”

“…It consists of a vertical reactor (riser), a fluid-bed regenerator, the stripper, and the lift line. A full description of the unit is given elsewhere …”

Relating Feedstock Composition to Product Slate and Composition in Catalytic Cracking. 6. Feedstocks Derived from Merey, a Venezuelan Crude

“…The fifth paper presented a revised gasoline correlation that included the atomic ratio of hydrogen to the sum of carbon plus sulfur, the feed fraction volatized at the cracking temperature, and the effective metals and nitrogen contents (both basic and amide type) . This nitrogen type determination is particularly relevant to the current research on mechanisms for NO x formation in the regenerator …”