The importance of catalyst grading is often underestimated when evaluating the overall efficiency of a hydroprocessing unit. If you only focus on the main bulk catalysts, you may miss out on the multiple operating benefits that a well-designed grading solution can provide.

All hydroprocessing feedstocks are different, each with its own unique profile of inorganic particulates and dissolved contaminants. As opportunity crudes and heavier feedstocks become more economically viable, the oil fractions you refine begin to pose new kinds of challenges.

That’s why it is essential to have the catalyst grading solution individually configured for your particular feedstock specifications and operating conditions. This will help you:

• Trap solid particles and other contaminants present in the feedstock
• Filter out catalyst poisons and metal corrosion debris
• Convert coke precursors

so you are able to:

• Ensure the most efficient hydrogenation activity
• Minimize pressure drop build-up
• Reduce downtime and revenue loss
• Achieve significant savings on catalyst replacement

Creating the best catalyst grading solution for your specific operating conditions requires access to a wide range of grading products. Topsoe supplies the industry’s widest range of sizes, shapes, and variety of inert grading solutions and active grading solutions. These differ in pore sizes, pore volumes, surface areas, activities, and affinity for specific catalyst poisons. This means we can design the perfect match for your specific feedstock – or even blends of feeds.

40 years of specialist grading have given Topsoe experts key know-how about why pressure drop occurs in refinery hydroprocessing reactors and exactly what causes the problem, when, why and how.

Based on a unique combination of on-site practical understanding as well as intensive, cutting-edge research, Topsoe has developed a comprehensive range of catalyst grading solutions to prevent and manage fouling before it stops production at your refinery.

Using grading materials of different shapes, sizes and specifications to create the required filtering effect in the reactor loading enables you to trap the largest inorganic feedstock contaminants in the upper layers and the smaller particles in the lower layers.

Topsoe grading products are designed with different void fractions and void sizes. The volume of each catalyst layer is configured to hold back the different sizes of inorganic particulates and reaction products in the graded bed system throughout the hydroprocessing cycle.

Some feedstocks contain corrosion products and other solid particles that don’t get held back by feed filters.

TK-26 TopTrap™ is an inert grading material specially designed to pick up iron scale and other inorganic contaminants. It is a macroporous material that features a large internal pore volume and void fraction that pick up even very small particles.

Sometimes the amounts of corrosion products and other contaminants are disproportionately high, and the grading required to deal with them without skimming would take up almost the whole the reactor. In such cases, the best solution is usually a scale catcher installation designed to prolong run length by preventing premature plugging of the catalyst bed below.

Such scale catchers put any unused space in the top of the reactor vessel to effective use, providing the feed with enough time to settle, while slowly overflowing onto the distribution tray(s) below. Topsoe scale catchers are a well-documented success in hydroprocessing reactors worldwide.

Catalyst milling sometimes occurs in hydroprocessing reactors, particularly in naphtha units, when the gas rate is high, and there is no gas-liquid distributor. It is also seen in units in which the inlet diffuse is poorly designed.

Topsoe provides the TK-15 catalyst to help you avoid such problems. This features a special shape and high density to ensure an effective hold-down function as well as a high void fraction.