By – Mark Lapinski, Steve Metro, and Kurt Vanden Bussche
With over 250 licensed UOP CCR Platforming units and 600 fixed bed type Platforming units, UOP has been the leader in reforming technology development since 1948. In step with numerous process, equipment, and control innovations, UOP has also developed many catalysts that push production limits and further maximize profitability for our customers. UOP catalysts have been designed to provide both high activity and high yields of reformate, hydrogen, and aromatics for motor fuel and aromatic applications. Specifically formulated high-yield catalysts offer an extra boost to higher yields, while higher density catalysts offer the highest activity with the ability to overcome catalyst pinning constraints. The high density catalysts enable processing more naphtha in the unit, increasing aromatic and/or C5+ production.
Development of New CCR Catalysts
CCR Platforming catalysts are bi-functional catalysts that contain both acid and metal functions. The acid function is provided by chloride on the alumina base, while the metal function is provided by Pt that is attenuated by Sn. The addition of other promoters offers improvements in yield selectivity by reducing undesirable cracking and promoting dehydrocyclization reactions. UOP has researched the addition of promoters extensively over the years and has concluded that the selection of a promoter for a commercial CCR reforming unit is dependent on (1) the impact on the performance including yields, activity, stability and coke make; (2) its effect on promoter to function correctly and consistently through many oxidation and reduction cycles; and (3) its ability to maintain other catalyst properties such as chloride retention. UOP is pleased to have developed a new high yield promoted catalyst: R-254. This new product leverages the proven success of UOP’s high yield R-274 CCR Platforming catalyst, commercialized in 2001, with over 15 loads in operation. R-254 catalyst retains the high yield and selectivity advantage of R-274 with a significant improvement in activity. This has been accomplished by modifying the manufacturing technique, while maintaining the same proven promoter technology.
Another new high yield catalyst has been formulated using UOP’s proprietary high activity, high density alumina base. The new R-284 catalyst employs the same density, metals and chloride levels as UOP R-264 CCR Platforming catalyst, but also contains the yield-enhancing promoter. For existing reforming units, the higher density of the R-284 catalyst can aid in processing high throughputs if constrained by catalyst pinning. For new CCR Platforming units,the performance and properties of the R-284 catalyst make it an ideal candidate to produce maximum aromatic and xylene yields for petrochemical production. UOP’s recent catalyst developments are illustrated in Figure 1.
R-254 Catalyst Case Study
Since the introduction of UOP’s R-254 catalyst in 2010, ten have applied this technology in commercial CCR Platforming units. The case study presented below summarizes the first application of UOP’s R-254 catalyst at the National Cooperative Refinery Association (NCRA) refinery in McPherson, Kansas, USA (presented at the American Fuel and Petrochemical Manufacturers Annual Meeting, March 11-13, 2012, San Diego, CA, USA). NCRA’s reformer is a UOP-designed CCR Platforming unit with an atmospheric regenerator with a three stacked reactor configuration. Originally a fixed-bed unit, the reformer was revamped by UOP to a continuous unit in 1992 and was loaded with UOP R-34 catalyst. In 2000, NCRA became the first user of UOP R-234 catalyst and in 2010, NCRA considered their next catalyst reload.
In general, there can be several factors that determine the timing of a CCR catalyst reload such as alumina phase damage due to high temperature excursions, metal poisoning from feed contaminants and end of life surface area. Other drivers for a reload include aligning the catalyst changeout with a scheduled unit turnaround and unit economics that justify replacing the current catalyst with a new generation CCR catalyst that increases the activity, selectivity, or throughput.
At NCRA, signs of decreasing catalyst activity and selectivity, specifically decreased H2 production, signaled the need for the catalyst reload. The loss of H2 was problematic since the reformer is the main source of hydrogen in the refinery. Chloride retention was low, requiring increased chloride injection. This led to salting issues in the stabilizer and a much higher reload frequency of the Cl treaters. The loss of performance and Cl issues were linked to CCR catalyst thermal damage, metals poisoning and the surface area level after 10+ years of operation in the unit. During NCRA’s reload assessment, they also considered UOP’s new R-254 catalyst. Based on improved yields of hydrogen, NCRA elected to load the new R-254 catalyst. The decision was influenced by (1) adequate heater capacity, (2) good experience with UOP as a licensor and as the first user of the R-234 catalyst, (3) UOP guarantees, (4) on-site UOP technical support, and (5) pilot plant testing of new and existing catalysts.
R-254 Loading and Performance
NCRA loaded the R-254 catalyst using UOP’s proven and proprietary “On-the-Fly” (OTF) reload procedure. The procedure allows uninterrupted processing of feed while the new catalyst is loaded and the old catalyst is unloaded. The changeout was conducted in February 2011 without any loss in unit throughput. The entire loading process lasted about one week.
NCRA monitored the catalyst selectivity, activity, coke make, chloride retention and fines make. Table 1 shows the results observed by NCRA for first six month period after the R-254 reload. The largest benefit was the increase in hydrogen ofabout 250 scf/b which allowed the steam methane reformer to be turned down significantly. Based on NCRA’s reformer feed rate in 2011 and an estimated cost of producing H2 at the steam methane reformer, a savings of $8,500 USD/day was realized ($3.1 MM USD/yr). Compared with the cost of the new catalyst load, a payback period of less than one year was realized. An important profitability factor included no loss in the production of reformate and hydrogen during the catalyst change out utilizing UOP’s proven OTF reload procedure.
Summary of observed commercial results at NCRA as a result of the catalyst change out from R-234 to R-254 catalyst. Data is for first 6 months of operation after the reload
|EOR R-234||SOR R-254||Change|
|C5+ Yield||75-76 LV%||76-77 LV%||1-2 LV% Increase|
|Chloride Injection||Base||20-50% Less||Decrease|
As shown in Table 1, the catalyst activity improved compared to the previous R-234 catalyst. NCRA reported that when operating with the R-254 catalyst at constant unit throughput at the same temperature, the reformate octane increased by 1+ RON. The higher activity of the R-254 catalyst was in part the result of the diminished condition of the 11-year-old catalyst. Operations with the new catalyst also resulted in a decline in the chloride injection rate by 20-50%. This led to longer life for the downstream Cl treaters and elimination of the salting issues in the stabilizer.
Additional information on the case study cited here can be obtained from the American Fuel and Petrochemical Manufacturers Annual Meeting paper from NCRA, March 11-13, 2012, San Diego, CA, USA. Please contact your UOP representative or the AFPM for a copy. A variety of catalysts including UOP’s R-234, R-264 and the new high-yield R-254 and R-284 catalysts are available for providing then best yield, activity and coke performance based upon unit objectives. Please contact your UOP Sales account manager for more details on how these new products could improve your profitability.