Catalysis 2023 Issue

60%

55%

52%

48%

Metal dispersion CO reduction efficiency (0.3 wt% additive)

50%

39%

38%

40%

31%

28%

30%

22%

18%

20%

10%

w/ m odel additive A-LD, fresh

w/ mo del additive A-MD, fresh

w/ m o del additive A-HD, fresh

w/ m odel additive A-LD, steamed

w/ m odel additive A-MD, steamed

w/o additive avg.

w/ m odel additive A-HD, steamed

Figure 5 Metal dispersion and relative CO reduction efficiency during temperature programmed oxidation (TPO) of spent catalysts with CO promoter additives at the same metal loading. LD = low dispersion, MD = medium dispersion, HD = high dispersion

CO promoter additive with high metal dispersion – refinery case study Following successful testing at laboratory scale, the per - formance of the new CO promoter additive, COP-NP HD, was compared with our best-selling CO promoter COP-NP at a North American refinery. The purpose of the trial was to match performance to COP-NP at a reduced metals cost. This FCC unit operates in full burn and has had a long his- tory of successful use of non-platinum promoter. Results from this trial showed equivalent afterburn and CO control using the highly dispersed non-platinum promoter with no change in NOx emissions. Performance between the two promoters was compared at similar dense bed tempera - tures (see Figure 7 ) and excess O 2 (see Figure 8 ). Both CO and afterburn are a function of dense bed tem- perature, as discussed previously in this article. Higher dense bed temperatures lead to reduced afterburn, as seen in Figure 7. Both COP-NP and COP-NP HD follow very similar trends at this refinery. CO and afterburn are also dependent on excess O 2. At this refinery, excess O2 has an impact on CO emissions, and both COP-NP and COP-NP HD showed similar performance (see Figure 8). Excess O2 can impact afterburn as well but had minimal effect at this refinery. Both additives performed similarly.

In addition to reducing sintering, optimised metal distri- bution throughout the mesoporous support particles fur- ther increases active sites available to anchor CO and O 2 required to carry out the CO oxidation reaction. Metal dispersion level and CO reduction efficiency were measured for three CO promoters with the same active metal loading and various dispersion levels, both fresh and steam deactivated (788ºC/95%H 2 O/20h) (see Figure 5 ). The additive with the highest metal dispersion exhib - its the highest CO reduction efficiency, for both fresh and steam deactivated versions. Metal dispersion in general has an inverse correlation with metal loading. Hence, it is critical to optimise the metal loading to identify the ‘sweet spot’ where the highest activ - ity level is obtained. Steamed CO promoter additives with various metal load - ings were assessed for metal dispersion and CO reduction efficiency (see Figure 6 ). The less metal content in the CO promoter additive, the higher dispersion was observed, leading to a volcano shape of activity vs metal loading. Based on these findings, we developed a new CO pro - moter additive with greatly improved CO reduction effi - ciency. The new additive has been successfully used in multiple refineries.

39%

40%

35%

Metal dispersion CO reduction eciency (0.3 wt% model additive, steamed)

35%

33%

31%

28%

30%

25%

20%

15.3%

14.5%

13.7%

10% 15%

10.2%

0 5%

0% 0%

w/o additive avg.

w/additive A

w/additive A-1 (150 ppm less metal)

w/additive A-2 (250 ppm less metal)

w/additive A-3 (400 ppm less metal)

w/additive A-4 (500 ppm less metal)

Figure 6 Metal dispersion and relative CO reduction efficiency during TPO of spent catalysts of CO additives with different metal loadings

Catalysis 2023