Introducing FUSION – the best of both worlds (ERTC)
One of the keys to optimal FCC catalyst performance is striking the right balance between zeolite and matrix, both in terms of selectivity and activity.
W R Grace & Co
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Historically, catalyst systems containing (1) a high matrix input to maximise conversion of bottoms and (2) a high zeolite input to impart favourable coke and gas selectivities have been known to outperform individual catalyst offerings. Grace has successfully commercialised these types of catalyst system in more than 100 refineries worldwide, and they continue to form a valuable segment of our industry leading catalyst portfolio today.
Up until now, however, the mechanism to unlock premium coke to bottoms performance has been achieved through the combination of complimentary catalyst components with individual matrix technologies. Through R&D, manufacturing and processing advances, Grace has developed a catalyst solution, FUSION™, which incorporates a differentiated advanced matrix binding system in a single catalyst particle. By reducing the proximate distance between multiple Grace technologies into the span of a single particle, the synergistic effects are magnified in this innovation to deliver premium catalyst performance for moderate and heavy metals applications:
• Improved FCC unit product selectivity
• Increased metals tolerance (vanadium and nickel) and bottoms conversion
• Optimised porosity for increased catalytic performance.
Conversion of heavier feedstocks with high contaminant metals is critical to maximising FCC unit profitability. Increasing the yields of the desired streams like cracked naphtha, middle distillates and light olefins remains an important target to generate an economic uplift for refiners. However, processing difficult and more cost-attractive feedstocks to produce high-value products remains a technical challenge due to limitations like wet gas compressor and air blower capacity. With the latest development of catalyst technology, Grace continues to innovate to tackle the pressures faced by the refining industry, to allow the profitable processing of ever changing and more challenging feedstocks around the globe.
A unique approach to catalyst design
The FUSION advanced matrix binding system deploys a combination of Grace technologies for intrinsic bottoms cracking and metals trapping into a single catalyst particle. This unique characteristic reduces the diffusion path length compared to alternative catalyst systems or separate particle metals trap solutions. Improved diffusion of heavy feed components facilitates pre-cracking of large feed molecules and, combined with the latest generation of metal trapping technologies, delivers premium coke selective bottoms cracking.
The single particle new catalyst technology maintains the level of mesoporosity in the 100 to 600 Å range found in traditional catalyst systems, but has a higher pore volume in the >1000 Å macropore range. Macropores of >1000 Å allow large feed molecules to effectively diffuse into the catalyst system, where the feed molecules subsequently reach the active sites and begin the series of cracking reactions. As a result, one of the key benefits of the new catalyst technology is additional bottoms cracking.
The pore size related signatures of the FUSION catalyst (higher macroporosity while maintaining mesoporosity to provide the ultimate combination of bottoms cracking with coke selectivity) are demonstrated in Figure 1.
Homogeneous metals tolerance
In addition to the new pore size benefits, new catalyst technology integrates the latest developments of commercially proven integral metals trapping technology. In many operations, the nickel content of Ecat is systematically growing, making it necessary to use catalysts with improved Ni trapping ability to avoid running into wet gas compressor constraints.
To confirm the effectiveness of Ni trapping in FUSION, Grace performed lab catalyst deactivation by spray coating Ni on the catalyst surface, followed by CPS deactivation, to give a metal distribution more comparable to that of Ecats where nickel is enriched on the outer shell of the catalyst particle.¹ X-ray powder diffraction (XRD) analysis was used as a tool to study the reactivity of γ-Al2O3 with nickel species to confirm the presence of the Ni passivator. The XRD pattern of the samples is shown in Figure 2. A broader reflection associated with gamma alumina is observed at 67.2θ for the sample containing no nickel (Figure 2a). Upon increasing the Ni level of the lab deactivated catalyst, a shift of the alumina peak to lower angular values reveals a modification of the alumina. This marks a progressive increasing of the unit cell (UC) of the alumina with increasing Ni content.2 A progressive enlargement of the unit cell indicates a strong interaction of nickel with γ-Al2O3, corresponding to the formation of a solid solution with Ni2+.
The progressive increase of the unit cell volume of the spinel-like phase of the sub-stochiomeric Ni alumina phase upon increasing the Ni content on the catalyst is plotted in Figure 3. The unit cell volume increases linearly with the Ni content. The linearity of the expansion of the UCV of the Ni rich spinel-like phase upon increasing the Ni level follows a Vegard’s type law which is described to be typical for solid solutions.3 This finding strongly indicates the preferential interaction of Ni2+ with γ-Al2O3 forming solid solutions of the formula NixAl2O3+x. The self-manufactured Ni-trap present in FUSION makes Ni2+ ions essentially non-reducible through the solid-state interaction under FCC conditions, and thereby reducing the extent of dehydrogenation reactions catalysed by Ni metal particles. This technology prevents enhanced coke formation as well as hydrogen production from Ni induced dehydrogenation reactions.
To verify the hypothesis of a strong interaction of nickel with γ-Al2O3, electron microprobe analysis was performed. Elemental mapping comparing the Ni with the Al map shows the preferential location of nickel on alumina particles which is seen as Al/Ni hotspots in Figure 4. Considering that for these experiments the Ni was loaded in one single step (spray coating), while in commercial application the catalyst is faced with several reaction-regeneration cycles leading to contact with a feed containing only a few mg/kg of Ni (limits the formation of NiO), the XRD and electron microprobe data confirm that the Grace alumina can trap significant amounts of Ni2+.
FUSION also employs Grace’s latest generation of Integral Vanadium Trap (IVT) which is an integral rare earth-based technology. While attempts using MgO- and CaO-based V traps may show promise under laboratory testing conditions, sulphur and silica within FCC regenerator conditions can poison the vanadium trap to form Mg2SiO4 (forsterite) and CaSO4 (anhydrite). The incorporation of Grace’s integral vanadium trap enhances stability and activity retention as it protects the zeolite from vanadic acid, enhancing stability. Resid feed catalysts that contain effective integral rare earth oxide-based vanadium traps provide differentiated performance even in units with low vanadium mobility. Electron microprobe analysis confirms that vanadium, which is mobile under FCC regenerator conditions, migrates to regions of concentrated RE from the incorporated traps, resulting in RE/V hotspots as indicated in Figure 5.
Step-out coke to bottoms performance
An ACE™ pilot plant was used to compare selectivities for FUSION against a corresponding traditional catalyst system. Both catalysts were impregnated with 3000 and 2000 mg/kg vanadium and nickel using spray coating and deactivated at the same conditions using CPS deactivation. At a given conversion, Figure 6 shows the same bottoms yield for both catalyst solutions, but the new catalyst technology offered a significant drop in hydrogen and coke yield. The improved gas and coke selectivity provides improved coke to bottoms performance, confirming the advanced matrix binding system causes a valuable interaction that outperforms traditional catalyst systems.
FUSION is the next example of an innovative FCC catalyst solution that is designed to provide differentiated product yields and physical properties with benefits in unit retention that can withstand dynamic and challenging FCC feed profiles. The combination of functional qualities and unique catalyst design architecture provides improvement in value to refiners. As product economies shift in 2020 and beyond, the new technology provides another tool to increase a customer’s bottom line. ν
1 Wallenstein D et al, Applied Catalysis A: General 462-463 (2013) 91-99.
2 Busca G et al, Applied Catalysis A: General 486 (2014) 176-186.
3 Tirsoaga A et al, Nanoparticles Res. 13 (2011) 6397-6408.
This short article originally appeared in the 2019 ERTC Newspaper, produced by PTQ / DigitalRefining.
You can view the digital issue here - http://www.eptq.com/digitalPTQ/2019-ertc/html5/index.html?&locale=ENG
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