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Refining Developments
52
ENHANCED PHYSICAL PROPERTIES
CCR moving bed catalysts also require careful attention to the physical properties to ensure mechanical strength and surface-area stability over many regeneration cycles, which is indicative of catalyst life and chlorine retention.
Accelerated aging tests have been performed on the new Quad-metallic catalyst to compare surface area retention to con-
ventional Pt-Sn bimetallic catalyst. FIG. 11 shows the surface area
decline over time following such test protocols. A conventional Pt/Sn catalyst reaches its end-of-life surface area (approximate-
ly 140 m2/g) relatively quickly, whereas the new Quad catalyst
retains a higher surface area in the range of 160 m2/g. Higher
surface area is associated with improved regeneration (Pt redis- persion) and better chloride (C1) retention. As a consequence, the new Quad catalysts will exhibit longer life, reduced salt de- posit in downstream units, and lower chloride content in the hydrogen-rich gas, resulting in longer chloride trap life.
Put in quantitative terms, the better surface area retention and intrinsically higher chloride retention resulting from a new quad catalyst with a proprietary promoter system results in 30% lower chloride injection over the life of the catalyst vs. standard Pt/Sn.
The mechanical properties of the catalyst are also impor- tant in CCR applications. Unlike fixed-bed catalysts, which are mainly concerned about crush strength to endure the static load forces within a fixed bed, CCR catalysts are spherical and designed to resist the dynamic forces from slow movement in the catalyst beds to pneumatic lifting between reactor and re- generator. These forces lead to particle attrition and fines pro- duction. Although the fines or broken pieces of the catalyst are captured within the system, they can lead to fouling of screens and increase pressure drop.
Highly developed CCR catalysts are more robust to ensure extended service over 7–9 years. New formulations are subject- ed to large-scale circulating test units to accurately represent commercial conditions and the forces leading to attrition. The new carrier and multi-promoted catalyst systems have proven to be as robust as previous-generation catalysts with an excel- lent track record of low particle attrition.
NOTES
As a licensor of catalytic reforming and aromatics chain technologies, and supplier of catalysts for these units, Axens is focused on continuous improvement in both process technology and catalyst development. The recent acquisition of the Criterion catalytic reforming catalyst business in 2011, including production facilities and know-how, provided a unique opportunity to compare, contrast and build upon two different approaches to reforming catalyst development and pro- duction. New proprietary formulations and production techniques have emerged from this union resulting in breakthrough catalysts for both fixed-bed and moving- bed CCR units that provide superior selectivity without compromising activ- ity and stability. Re-engineered fixed-bed catalysts are under development and on-track for release in 2013. These new products promise the benefits of higher selectivity and reduced cost through promoter selection and loading optimization.
PIERRE-YVES LE GOFF is Axens’ senior technical manager for reforming catalysts and project leader for catalyst development. Dr. Le Goff started his career as a research engineer at Rhodia, where he specialized in catalyst support design and process development. Dr. Le Goff holds an engineering degree from the École de Chimie de Mulhouse, an MBA from Université de la Sorbonne in Paris, and a PhD from Université de Haute-Alsace.
JAY ROSS is a senior technology and marketing manager for Axens covering the field of transportation fuels including FCC, catalytic reforming, isomerization and biodiesel production. He has over 30 years of experience in the refining and petrochemical industry including process engineering design, R&D, licensing and technical assistance. Mr. Ross is a graduate from Princeton University with a degree in chemical engineering.
JOSEPH LOPEZ is a development and industrialization engineer in Axens’ production plant of adsorbents and catalysts in Salindres, France. He is responsible for the development and scale-up of reforming supports and catalysts. He started his professional career as a research engineer at Rhodia working mainly in the field of
heterogeneous and homogeneous catalysis. Dr. Lopez holds an engineering degree from the Ecole Nationale Supérieure de Chimie de Montpellier and a PhD in catalysis from the Université Claude Bernard of Lyon.
Quad ≈ 20 m2/g Bi-metallic 120 140 160 180 200 220 0 100 200 300 400 Time
Specific surface area, m
2/g
Bi-metallic Quad-metallic
FIG. 11. Catalyst surface area aging test, quad metallic vs. bimetallic Pt-Sn.