Tamoil s Collombey refinery in

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1 Multistage reaction catalyst with advanced metals tolerance The metal trapping capabilities of a catalyst gave a refiner greater flexibility to upgrade heavy residue feed with increased metals content in its RFCC unit YVES-ALAIN JOLLIEN Tamoil JEREMY MAYOL, VASILEIOS KOMVOKIS and CARL KEELEY BASF Tamoil s Collombey refinery in Switzerland operates an R2R design residue fluidised-bed catalytic cracking (RFCC) unit. (The R2R process is offered through the FCC alliance between Axens, IFP Energies Nouvelles and Technip Stone & Webster Process Technology.) It has a two-stage regenerator. The feedstock is 100% atmospheric residue derived from crudes such as Es Sider, El Sharara, Saharan Blend and Brega with a moderate-to-high metals content and a high Conradson carbon residue (CCR) content (typically 4-6 wt%). Increased flexibility to upgrade heavy residue feed with even higher metals is a key enabler for further improving the profitability of the Collombey refinery. Base catalyst in use Collombey changed to BASF s Aegis catalyst during the first half of This catalyst combines the benefit of BASF s DMS and Prox- SMZ technology platforms. It is designed for resid feed applications where moderate-to-high metals tolerance is needed, and it offers the flexibility to improve both diesel and gasoline yields. Compared to the best-proposed solution of a competitor, Aegis delivered improved LPG/gasoline selectivity at a low equilibrium catalyst (e-cat) rare earth level, similar gasoline and coke yields, and better bottoms upgrading, all leading to a profitability increase of $0.40/bbl of fresh feed. 1 To satisfy changing feed quality and product slate demand, and to continuously maximise the unit s profitability, the Aegis catalyst was fine-tuned several times during the first year of operation. Unit operating data are routinely reviewed using BASF s Technical Support Service (TSS), and this identified that catalyst performance could be further improved through even better feed metals passivation. This triggered a review of catalyst technology options. Using BASF s Catalyst Change Management Process, Fortress catalyst, based on the company s Distributed Matrix Structures Contaminant metals vanadium and nickel increase catalyst deactivation and hydrogen yield (DMS) and Multi-stage Reaction Catalyst (MSRC) technologies, was selected as the best option. 2 The changeover to the customised Fortress catalyst proceeded smoothly, and the new catalyst delivered excellent performance. Using typical feed and product values, the profitability has been increased by $0.30/bbl of fresh feed compared to the Aegis catalyst. Thus, this past year, the refinery has improved profitability by approximately $0.70/bbl (Aegis and Fortress). This article shows how advanced FCC catalysts and value-added technical service are supporting Collombey refinery. This is made possible by Collombey s good approach to data sharing and collaboration to form the best team. Impact of feed metals on FCC operation The contaminant metals in residue feed that need to be controlled by the FCC unit are mainly vanadium (V) and nickel (Ni), with iron (Fe) and calcium (Ca) also high from some crudes. Sodium (Na) is typically reduced to low levels by crude desalting. The potential detrimental effects of these metals on FCC performance are summarised below: Ni: dehydrogenation activity leading to increased H 2 and coke V: catalyst deactivation, with some dehydrogenation activity Fe and Ca: surface pore plugging and nodules formation at higher levels, leading to conversion loss, higher dry gas yield and possibly catalyst circulation problems Na: involved in catalyst deactivation (more information below). This article focuses on mitigating the deactivation/dehydrogenation effects of Ni and V through the application of the appropriate catalyst technology to passivate these metals. Improving FCC catalyst vanadium tolerance As previously indicated, V deactivates the catalyst, and increased feed V will require higher catalyst additions to maintain the optimum target e-cat activity. The deactivation steps are: 6 V is deposited onto the catalyst and is oxidised in the FCC regenerator The oxidised form undergoes further reactions to form several PTQ Q

2 highly mobile types of vanadic acids These vanadic acids remove Na+ from the zeolite exchange sites The sodium vanadate hydrolyses to sodium hydroxide (Na+OH-) The hydroxyl group (OH-) then attacks the silica-oxygen zeolite framework, leading to zeolite collapse, destruction and catalyst deactivation. There is residual Na+ on the fresh catalyst from the manufacturing process. In BASF FCC catalysts, the amount of residual Na+ on zeolite is reduced to ultra-low levels by a unique combination of calcination and ion exchange steps, which improves resistance to Na-V zeolite deactivation. Impact of H2 and coke on FCC operation Additional production of H2 and coke from processing high metals content and high CCR feeds has a significant impact on FCC unit operation, as most units operate to gas and coke handling limits. High volumetric flow from the low molecular weight H2 may lead to wet gas compressor and gas concentration unit capacity limits. In addition, at many refineries, H2 Zeolite crystallites SEM = Scanning electron microscopy TEM = Transmission electron microscopy SEM Concentration, wt% 0.5 TEM Matrix crystallites Figure 1 DMS selective pre-cracking by exposed outer surface of zeolite in the absorber off-gas from the FCC s gas concentration unit is routed to the refinery fuel gas system, where it has a low economic value ample reasons to focus on minimising the formation of H2 in the FCC unit. Coke is any carbonaceous, high molecular weight, non-volatile resi due formed from cracking. The maximum tolerable coke yield/ production may be constrained by regenerator operating limits; for instance, due to air blower capacity Electron micro-probing 0.6 Macropore limits or mechanical design temperatures limits. There are four types of contribution to FCC coke: contaminant metals, feed additive, cat-to-oil (strippable) and catalytic. This article focuses on controlling contaminant metals and catalytic coke. Contaminant metals coke results from reactions due to feed metals acting as dehydrogenation catalysts; for example, Ni and V, which remove H2 from hydrocarbon molecules, thereby increasing the tendency to form coke. Catalytic Scanning electron microscopy V Ni Nickel Distance from centre, microns 50 Two-stage Fortress catalyst Alumina Flex-Tec Fortress catalyst Figure 2 Development story for Multi-stage Reaction Catalyst and Fortress catalyst PTQ Q

3 coke is formed by thermal and catalytic reactions. The formation of coke on the catalyst results in catalyst deactivation due to the blocking of active acid sites. Thus, the coke must be burnt off the catalyst in the regenerator to restore its activity. The coke burning requires oxygen from the air supplied from the air blower, and the reaction generates a significant heat release. Heat generated from burning coke drives up the regenerator temperature. This can contribute to higher catalyst deactivation and fresh catalyst consumption, reduced equipment operating life, as well as lower conversion due to reduced cat-to-oil. Thus, it is always very important to control the production of coke, and this is particularly challenging when processing residue feed. The risk of excessive H 2 and coke production associated with processing residue feed can be mitigated by the use of advanced FCC catalyst technologies. Advanced FCC catalyst technologies To improve coke selectivity, BASF developed the unique DMS technology platform. 3 In DMS, the matrix is designed to provide enhanced diffusion of the feed molecules to pre-cracking sites located on the external, exposed surface of highly dispersed zeolite crystals (see Figure 1). The feed initially cracks on the Appraise Data review Cold eyes review Process Modelling (statistical and kinetic) Select Catalyst Additives Services Logistics Forming the best team Challenges the status quo! Process Define Value addition Risk minimization plan Trial procedures etc. Results Tailored solution Addresses all needs Figure 4 BASF s Catalyst Change Management Process Performance evaluation Operation optimisation Operating data Progress check Process analysis Figure 3 Information flow using BASF s TSS zeolite outer surface, rather than on the active amorphous matrix material. This difference provides the potential for improved selectivities with the reduced coke formation characteristic of zeolite cracking. The formation of coke on the catalyst results in catalyst deactivation due to the blocking of active acid sites Implement Trial procedures Monitoring etc. Improve All aspects of FCC operation Deliver culture change Shifts focus to continuous profit improvement The secondary diffusion pathway of the cracked products to the internal crystalline zeolite surface is also minimised, resulting in less over-cracking (undesirable conversion of gasoline to LPG, dry gas and coke). The net result is higher bottoms upgrading, with lower delta coke (wt% coke yield/cat-tooil), leading to an increased yield of valuable products. It is generally accepted that the dehydrogenation activity of metals can be expressed in terms of equivalent nickel as Ni + V/4 + Fe/10 + 5Cu. Typically, residue feeds contain large amounts of Ni and V, and sometimes Fe, while copper (Cu) levels are usually very low. This relationship shows that it is especially important to mitigate the dehydrogenation effect of feed contaminant Ni. This is done within FCC catalysts by incorporating an active speciality alumina into the matrix to trap the Ni. Equilibrium FCC catalysts have been examined under electron microscopy. From this work, it has been generally observed that V is distributed throughout the particle, and Ni mainly deposits and accumulates on the outer 5-15 micron layer of the e-cat 4,5 when processing resid (see Figures 2a and 2b). Conventional manufacturing techniques, practised by all FCC catalyst suppliers, result in the active speciality alumina being more or less evenly dispersed throughout the particle. This leads to a large proportion of the interior alumina being unavailable to react with the surface-deposited Ni; this interior alumina is essentially wasted. By using BASF s MSRC technology (see Figures 2c and 2d), the spatial distribution of the speciality alumina within the particle is optimised to maximise its efficiency in Ni trapping and this leads to improved catalyst performance. 2 This technology has been incorporated into BASF s Fortress catalyst. Fortress catalyst is a two-stage catalyst based on the MSRC technology. The catalyst outer-stage is based on the DMS technology 3 (see Figure 1), but is enriched with speciality alumina to trap Ni where it enters and deposits on the catalyst surface. The catalyst inner-stage also has the DMS structure (see Figure 1) to allow enhanced diffusion of heavy molecules and selective pre-cracking on the exposed outer zeolite surface, maximising conversion. Using the MSRC technology, these stages are chemically bound together by 134 PTQ Q

4 zeolite and the catalyst particle is manufactured in such a way that all physical properties, including attrition resistance, are similar to other DMS based products (for instance, Flex-Tec catalyst, which is used for targeting conversion maximisation. It cracks severe resid feeds while maintaining high activity with low coke and gas formation). In addition, the improved spatial distribution of the Fortress Ni-trapping alumina offers better performance potential. The features described above that improve Ni and V tolerance have been incorporated into the Fortress catalyst tested in the Collombey refinery RFCC unit. The excellent results achieved by this catalyst and technology are described below. Trial results The typical feed processed by Collombey s RFCC unit is 100% atmospheric residue with moderate-to-high metals content and a high CCR (typically 4-6 wt%). Routine unit data reviews using BASF s Technical Support Service (TSS, see Figure 3), revealed that FCC profitability could be further improved through better feed metals passivation. Trial objectives The trial s objectives were to reduce H 2 production to minimise the amount of H 2 sent to refinery fuel gas, and to control LPG/gasoline selectivity and total LPG+gasoline production at the same delta coke, conversion level and bottoms upgrading performance delivered by the Aegis catalyst. Using BASF s Catalyst Change Management Process (see Figure 4), Fortress catalyst was selected and customised during the trial to improve profitability. This process combines FCC operations review (cold eyes review), state-of-the-art modelling (statistical and kinetic), basic and advanced ACE pilot unit testing, and a proactive risk minimisation plan, to ensure a flawless catalyst change to deliver an improvement in unit profitability (measured in $/bbl). Using TSS (see Figure 3) to standardise the unit data, the average Conversion, wt% Catalyst consumption, kg/mt feed Figure 5 TSS corrected conversion (221 C minus) vs catalyst consumption conversion increased by a remarkable 3-4% at iso-catalyst addition rate (see Figure 5). A reduction in the catalyst consumption was enabled by higher activity retention. At A B Catalyst addition, MT/day E-cat activity FACT, (using wt% FACT), wt% /10/2012 1/11/2012 1/12/2012 1/1/2013 iso-metals in feed, the fresh catalyst consumption was reduced to a record low rate of 4 MT/d (see Figure 6a). During the trial, improvements were also made in the approach to control e-cat 1/10/2012 1/11/2012 1/12/2012 1/1/2013 1/2/2013 1/3/2013 1/4/2013 1/5/2013 1/6/2013 1/7/2013 1/2/2013 1/3/2013 1/4/2013 1/5/2013 1/6/2013 Figure 6 TSS corrected a) catalyst addition rate, b) e-cat activity vs time 1/7/ PTQ Q

5 A B H 2, wt% Coke factor Ni + V / 4 4 / 3 Sb, ppm Ni + V / 4 4 / 3 Sb, ppm Figure 7 ACE unit a) hydrogen yield, b) coke factor vs equivalent Ni BASF Fortress catalyst trial summary Competitor (base) BASF Aegis BASF Fortress High Z/M Optimised Z/M Optimised Z/M Base ZSA Higher ZSA than base Higher ZSA than base Base MSA Higher MSA than base Higher MSA than base %RE = 3.3 %RE = 2.8 %RE = 2.6 Feed-specific gravity Feed rate, bbl/day Catalyst consumption, kg cat/mt feed Dry gas, wt% LPG/gasoline, wt%/wt% LCO/slurry, wt%/wt% Coke, wt% Economics, $/bbl of FCC feed Base Base Base Using TSS to standardise the unit data, the average conversion increased by a remarkable 3-4% at iso-catalyst addition rate trapping speciality alumina is concentrated in the outer-stage, which improves Ni tolerance and performance. Consistent with the lower H 2 yield, Figure 7b shows improved coke selectivity. Dry gas yield was on the lower side (see Table 1) and total LPG+gasoline yields were similar to the previous results with the Aegis catalyst (see Figure 8a). Similar performance was achieved by optimising the catalyst formulation (zeolite surface area, matrix surface area, rare earth level on zeolite and so on). However, bottoms upgrading to LCO was significantly increased using Fortress catalyst, compared to the previous unit record that was set by the Aegis catalyst. 1 The increase in the LCO/slurry ratio at higher conversion was 12-15% (see Figure 8b). Collombey refinery did not observe any problems with attrition resistance. In Fortress catalyst, the stages are chemically bound together by zeolite in such a way that all physical properties, including attrition resistance, are similar to other DMS based products (for example, Flex-Tec). Table 1 activity within the desired range, with the result that more often the e-cat activity is controlled within the target operating window (see Figure 6b). BASF s Fresh Catalyst Addition Tool was helpful in this regard. At a lower fresh catalyst addition rate, the level of contaminant metals increased on the e-cat. The Ni+V on e-cat increased to ppm. To eliminate the effect of varying feed quality and operating conditions during the trial, an ACE unit was used to assess the improvement in coke selectivity using standardised feed and operating conditions. Figure 7a shows a hydrogen yield reduction even though the Ni level on e-cat increased during the trial. In the Fortress catalyst, the Ni- Economic assessment The increased refinery profitability estimated using typical feed and products values is summarised in Table 1. Conclusions This article has shown how advanced FCC catalysts and valueadded technical service are supporting Collombey refinery. This is all made possible by Collombey s good approach to data 136 PTQ Q

6 A B LPG + gasoline, wt% LCO/slurry, wt%/wt% Conversion, wt% Conversion, wt% Figure 8 TSS corrected a) Total LPG + gasoline yield, b) LCO/slurry ratio vs conversion US), with similar results observed at all locations. Acknowledgements The authors would like to thank Steve Challis of Chalcat Consulting Limited, UK, for chairing numerous cold eyes reviews at site and providing consulting during the BASF catalyst trials. References 1 Jollien Y-A, et al, Use an innovative cracking catalyst to upgrade residue feedstock, Hydrocarbon Processing, Feb 2013, McLean J B, et al, Multi Stage Reaction Catalyst: a breakthrough in FCC catalyst technology, NPRA AM McLean J B, et al, Distributed matrix structures a technology platform for advanced FCC catalyst solutions, NPRA AM Kugler E L, et al, Nickel and vanadium on equilibrium cracking catalyst by imaging secondary ion mass spectrometry, Journal of Catalysis, 109, 1988, 387, 5 Lappas A A, et al, Effect of metals poisoning on FCC products yields: studies in an FCC short contact time pilot plant unit, Catalysis Today, 65, 2001, Xu M, et al, Pathways for Y zeolite destruction: the role of sodium and vanadium, Journal of Catalysis, 207, 2002, sharing and collaboration to form the best team. Combining the refinery s operating expertise and BASF s catalysts and technical support, it was possible to further improve flexibility to upgrade heavy residue with even higher metals content. Fortress catalyst was selected for a trial in This is a two-stage reaction catalyst based on BASF s DMS and MSRC technologies. The outer-stage of the catalyst is enriched with speciality alumina to trap Ni where it enters and accumulates on the catalyst. The improved metals tolerance delivered by this catalyst has increased the profitability of Collombey s RFCC unit by $0.30/ bbl of FCC feed compared to the Aegis catalyst. Thus, this past year, the refinery has improved profitability by approximately $0.70/bbl (Aegis and Fortress). The Fortress catalyst delivered: A 3-4% conversion increase at iso-catalyst addition rate Due to high activity retention, at iso-feed metals, fresh catalyst addition can be reduced to a record low rate of 4 MT/d Bottoms upgrading to LCO was significantly increased. The increase in the LCO/slurry ratio at higher The outer-stage of the catalyst is enriched with speciality alumina to trap Ni where it enters and accumulates on the catalyst conversion was 12-15% Attrition resistance was similar to previously used catalysts. Fortress catalyst is currently in operation at four other refineries (one in the UK and three in the Yves-Alain Jollien is a Process Engineer for Tamoil S.A. Raffinerie de Collombey and is the FCC Unit Process Engineer. With over six years of experience, he holds an MEng degree from the Swiss Federal Institute of Technology Lausanne and later studied for one year at the IFP School near Paris. Jeremy Mayol is a Technical Account Manager, Refining Catalysts for EMEA with BASF Corporation. With over 15 years of experience, he is a recognised technical specialist in FCC unit operation. He has worked for BASF for four years and previously spent 12 years working for INEOS and BP. Vasileios Komvokis is the Technology Manager, Refining Catalysts for EMEA with BASF Corporation. He holds BS and MS degrees in chemistry and a PhD in chemical engineering from Aristotle University, and was a researcher at CPERI and a research Professor at the University of South Carolina. Carl Keeley is the Marketing Manager, Refining Catalysts for EMEA with BASF Corporation. He holds a MEng in chemical engineering and applied chemistry from Aston University, UK, is a professional engineer (CEng) and has over 12 years of experience. Previously, he worked with UOP, BP and Dow. PTQ Q