Topsoe’s hydroprocessing development

Topsoe has been researching the catalytic mechanisms of hydrotreating since the early 70’s, and in the mid-90’s Topsoe expanded the hydroprocessing portfolio to also include hydrocracking.

Hydroprocessing catalysts

The catalyst is the key to most hydroprocessing applications. HDS and HDN catalysts generally consist of sulfides of Co and Mo or Ni and Mo on a high surface area support such as aluminium oxide. Ten-fold improvements in activity have been achieved since the first hydrotreating catalysts appeared on the market.

Active sites on hydroprocessing catalysts

Topsoe researchers were the first to propose the existence of Type I and Type II CoMoS sites for direct desulfurization, and the first to identify the brim sites for hydrogenation.

Pressure drop control

Topsoe’s graded bed technology was the first to efficiently counter pressure drop build-up in the reactor. The research was based on an understanding of the pressure drop mechanisms which formed the basis of the development of Topsoe’s extensive graded bed catalyst portfolio.

Reactor internals

Topsoe was first to recognize that conventional bubble-cap and chimney type distributors were inadequate to meet the emergent requirements for higher performance in diesel and VGO hydrotreaters in the early 1990’s. This lead through detailed research based on Topsoe’s operating experiences, semi-scale cold flow models and application of the latest in CFD modelling techniques to development of state-of-the-art reactor internals.

ULSD catalyst and technology

Topsoe was a pioneer in ULSD based on a fundamental understanding. Our approach is to combine a fundamental understanding of the catalytic and process aspects with empirical knowledge. Through our detailed understanding of the different reaction routes for sulfur removal, the inhibitors and the deactivation rates for the different reaction routes, Topsoe was the first to revamp and design new hydroprocessing units at low pressure for ULSD production. Improved catalysts are developed through a detailed understanding of the carrier, the surface and the active sites.

Catalyst development

Through detailed understanding of both Type I and Type II CoMoS sites for direct desulfurization, the brim sites for hydrogenation, the understanding of different reaction routes and the inhibitors for each reaction route, Topsoe has developed the BRIM™ catalyst technology.

Coker naphtha

Topsoe has developed a novel coker naphtha technology combining selective di-olefin saturation to control gum formation, with a unique removal of Si through understanding of Si-components in naphtha, Si-removal activity and the influence of Si-deposition on the activity of the hydroprocessing using state of the art catalysts.

Renewable diesel

Based on a detailed understanding of the mechanisms of hydroprocessing different bio-materials, Topsoe researchers have developed catalysts and technology to tackle the issues of high exotherms, fouling, CO/CO2 inhibition and cold flow properties.


Based on a detailed understanding of the acidity and functionality of the zeolite, the nitrogen management and the product properties, Topsoe has developed outstanding hydrocracking catalysts and processes.

The kinetics of ULSD

Our research reveals that the mechanisms involved in the conversion of the most refractive sulfur compounds in diesel differ from those for the more easily removed sulfur compounds. Our research has identified the most refractive sulfur compounds as well as certain nitrogen-containing compounds present in diesel oils that act as inhibitors for the hydroprocessing catalysts. This has led to a detailed understanding of the kinetics of deep HDS of diesel enabling us to choose the right catalyst and operating conditions for a given application and to reduce the overall investment and operating costs associated with production of ultra-low sulfur diesel.

Understanding - the basis for development

Our approach is to combine a fundamental understanding of the catalytic and process aspects with empirical knowledge. Using state-of-the-art analytical techniques such as SEM, TEM, STM, DFT, Raman and IR  and Mössbauer, we achieve a detailed understanding of the carrier, the surface and the active sites, which forms the basis for the development of improved catalysts.

Optimizing process layout

One of Topsoe’s recent focus areas has been the coker naphtha hydrotreating technology. Combining process and catalyst technology, Topsoe has overcome the challenges of silica poisoning and control of the temperature increase from saturation of olefins.

BRIM™ - discovering the edge

Meeting sulfur specification standards

An ever-increasing awareness of the environment has meant an increased focus on environmental standards and an increased demand for Ultra-Low Sulfur Diesel – ULSD. This has entailed steeper requirements for the refining industry and tighter sulfur specification standards. Topsoe’s BRIM™ catalyst was developed for hydrotreating in response to changing sulfur emission standards. 

Catalytic reaction sites

Topsoe has worked to improve the hydroprocessing catalysts used for sulfur removal in the refining industry for decades, over the years bringing ever-improving catalysts to the market: Henrik Topsøe and his team’s discovery of the Type I catalytic reaction site ensured the development of catalysts with a higher density of sites for direct desulfurization, and the later discovery of the Type II reaction site further increased the catalytic activity level. 

The atomic scale

Working side by side top scientists from Denmark’s Technical University and the University of Aarhus, Denmark, Topsoe’s Research and Development used a scanning tunnelling microscope (STM) to observe chemical reactions at atomic level. The aim of the project was to study the nanocrystals of molybdenum disulfide in order to better understand how they work in hydrodesulfurization catalysis (HDS), an essential step in the refining industry’s hydroprocessing. 

“The STM microscope functions like an atomic gramophone which scans the structure of the surfaces. When we studied the pictures, it was quite surprising that the structure catalytically active edges and the BRIM® condition of the small nanocrystals is different to that on larger nanocrystals”, says Research Scientist Stig Helveg. 

The “BRIM® sites”

Topsoe’s researchers discovered that the molybdenum disulfide nanocrystals carried more active catalytic reaction sites close to the edges of the nanocrystals. Therefore researchers named the new catalytic sites “brim sites”.  

Topsoe’s BRIM® technology has generated international interest from researchers and our industrial clients. 

“Through our catalytic development approach and a fruitful collaboration with universities, Topsoe’s BRIM® discoveries have generated a new generation of catalysts which enable our clients to meet sharper environmental standards”, says Henrik Topsøe, Executive Vice President. “Topsoe’s unique approach lies in the ability to transfer our know-how to the production of catalysts with more active brim sites”.