Accu® Sphere Catalyst Carrier: Size Uniformity and Formulation Adaptability Gains Commercial Acceptance (Article)
July 3, 2019
Saint-Gobain NorPro introduced the Accu® spheres brand in 2018 to address demands for small diameter (typically less than 3 mm) spherical catalyst carriers. They are effective in several commercial applications for both fixed and moving bed reactors, showcasing an inherent ability to remove contaminants and coking. This attribute is exceptionally well suited for applications where catalyst regeneration is required, including catalytic biofuel applications.
Accu sphere catalyst carriers
The size of Accu spheres is optimized to balance pressure drop and external surface area, while porosity and internal surface areas are tailored to suit a specific catalyst and chemical reaction. They are produced with a narrow size distribution and feature unprecedented size uniformity, providing high geometric surface area, uniform packing and even flow distribution. These highly adaptable spherical catalyst carriers are also available in multiple formulations, compositions and properties in a range of sizes from 0.3 mm to over 4 mm, drawing interest from chemical, petrochemical, refinery and biofuels markets.
Accu spheres’ key attributes:
- Narrow size distribution
- Excellent control to average particle size
- Tailored porosity and internal surface area
- Multiple formulations available including: alumina, silica, titania, zirconia, zeolites and mixed oxides
- A gradient of chemistries within each particle is possible
Case study No. 1: Illustrating size control
Saint-Gobain NorPro produces Accu spheres using a unique manufacturing process that yields excellent control over average particle size. Their process ensures excellent repeatability and particle size distribution has an average absolute error of just 1.5%, with a span of less than 15% between D10 and D90.
The narrow size distribution and unprecedented size uniformity of Accu spheres complements Saint-Gobain’s traditional mono-sized spherical catalyst carrier, Unispheres® carriers, which are considered highly mono-sized themselves. Unispheres carriers are available in a range of sizes from 1.6 mm to 8 mm. However, at the smaller diameter sizes, Unispheres carriers yield and size control are reduced. In contrast, 1.6 mm Accu spheres maintain a mean diameter within 0.8%, while the mean diameter of Unispheres carriers can be up to 6.7% of its target value.
| Technology | UniSpheres® | Accu® Spheres |
|---|---|---|
| Target median diameter (mm) | 1.6 | 1.6 |
| N, BET surface area (m2/g) | 248 | 279 |
| Hg intrusion volume (cm/g) | 0.89 | 0.82 |
| Average pore diameter (a) | 94 | 93 |
| F.P.C.S. (lb) | 3.5 | 3.7 |
| PSD CamSizer, D10 (µm) | 1152 | 1479 |
| PSD CamSizer, D50 (µm) | 1493 | 1587 |
| PSD CamSizer, D90 (µm) | 1700 | 1705 |
| Deviation from target D50 (%) | 6.7 | 0.8 |
| Span (D90 -D10) / D50 (%) | 36.7 | 4.2 |
| Accu spheres provide for narrow size distribution and unprecedented size uniformity. | ||
Case study No. 2: Economic benefits of a gradient of chemistries
Saint-Gobain NorPro has a unique ability for producing Accu spheres with a gradient of chemistries and has introduced the concept to reduce the high cost associated with some higher-performance catalyst carrier materials such as zirconia or high purity silica. Accu spheres can be produced with a controlled and varied chemistry from the surface through to its core.
These novel core and shell particles are new in the industry and Saint-Gobain NorPro has the expertise to prepare these spherical support particles in several different chemistries. In the examples below, the first figure showcases a 350 micron dense alumina core accompanied by a 100 micron silica coating. The second figure depicts variance in zirconia content with element mapping completed by energy-dispersive X-ray spectroscopy. In both instances, the higher-cost media is distributed across the outside of the spherical catalyst carrier where the physical properties of the higher cost media are most influential to process parameters.
Few vendors make comparable-sized spheres in large quantities, and those that do are typically limited in size or by material composition. Saint-Gobain NorPro Accu spheres are developed and prototyped for the intended application, with custom samples available upon request.
The company’s unique, customer-driven proficiency is supported by a 50- to 100-ton per year development plant. They can tailor porosity and produce a range of sphere sizes in large quantities, in multiple compositions, with varying properties and chemistries.
Saint-Gobain NorPro also has extensive experience in material science and raw material characterization. They can provide catalyst carrier media in a wide range of refractory metal oxides inclusive of alumina, rare-earth metal oxides, zirconia and titania, and typically function as a one-stop turnkey solutions provider. In fact, nearly 90% of sales are comprised of a custom proprietary catalyst carrier co-developed with customers for a specific application.
Saint-Gobain NorPro Accu spheres are commercially available and these new micro-sized catalyst carrier spheres meet the industry's ever-growing demands. They are ideal for slurry or moving bed reactors where coking and constant catalyst generation are required and have wide employment in chemical, petrochemical, refinery and the rapidly growing biofuels markets.