Apr-2024

Incorporating new technology and tools for catalyst development

Factors affecting advances in catalyst development benefit from a wide range of expertise.

Rene Gonzalez
Editor, PTQ

Article Summary

Efficient conversion of fossil-based and renewable feedstocks to fuels and petrochemicals compels better performance from downstream catalytic conversion processes. Improving reactor performance equates to improved catalyst capabilities. Close adherence to the following developments plays a key role in developing and applying high-performance catalysts:
• Sustainable catalyst applications
• Zeolite and shape-selective catalysis
• Single-atom catalysts
• Advancements in hydroprocessing catalysts
• Advanced simulation and AI applications.

Sustainability
Compared to refinery operations a generation ago, sustainability is on par with profitability. Some would say it takes precedence. For example, the industry’s dual focus on producing zero-emissions fuels while controlling emissions from major refinery conversion units, such as the fluid catalytic cracking (FCC) unit, demonstrates how sustainability can be achieved over a wider operating window.

Against this backdrop, demonstrated sustainability can also be seen with more effective and environmentally benign catalysts, such as FCC additives with more durable precious metals via support surface morphology. Sustainability strategies play an important role in the elimination of hazardous byproducts ranging from metals contaminants to sulphur-bearing compounds. This calls for continuous addition to a catalyst’s capabilities, such as when upgrading biomass-derived materials.

Much has been discussed on hydrocarbon feedstock pretreatment, such as FCC feed pretreatment. However, catalyst contamination and deactivation with the higher volumes of renewable and biofeeds entering the market are relatively new. For example, with the bioconversion of lignocellulosic feeds, conversion limits with these new feed types can be resolved using pretreatment systems to disintegrate cross-linked fractions of lignocellulosic biomass. Pretreatment can avoid other unexpected challenges when introducing biomass feeds into a hydrotreater and its catalyst. For example, even when co-processing less than 10% biomass through a hydrotreater, problems such as disproportionately large heat releases have been observed.

Zeolite catalysts
The zeolite class of crystalline aluminosilicates continues to play a crucial role in refinery and petrochemical catalysis. Their shape selectivity allows them to discriminate between molecules based on size and shape. This feature is particularly advantageous in the cracking of hydrocarbons, contributing to increased yields of desired products while minimising unwanted byproducts, such as with the alkylation of butylenes over a zeolite catalyst to meet demand expected to reach 670 thousand tonnes by 2035, compared to around 500 thousand tonnes in 2023, according to a ChemAnalyst study. Besides its well-established role as a gasoline octane-enhancing additive, its market value is rapidly extending into areas from solvents to plasticisers, to name a few.

Zeolites’ three-dimensional framework structure of tetrahedral atoms provides high surface area, acidity, and shape selectivity. Improvements in refinery zeolites aim to enhance their catalytic efficiency, selectivity, and stability. Some areas of improvement include enhanced porosity for more efficient accessibility of reactants to active sites and improved overall catalytic activity. Tailoring the pore size and shape of zeolites to match specific hydrocarbon molecules allows for better shape selectivity in catalytic reactions, improving the efficiency of processes such as isomerisation and FCC.

Resid upgrading trends involving the FCC unit benefit from advances in zeolite materials. Just recently, Grace’s FCC Segment Marketing Manager, Dr. Bani Cipriano, said, “One of the trends we see is that the economics of upgrading resid in the FCC are very strong. Our customers are taking advantage of this trend, processing heavier, higher metal laden feeds. Using generic economics, in one trial we estimated use of trademarked PARAGON catalyst resulted in $0.65/bbl of value delivery which translates into $14MM per year for an average size FCC.”

Other important zeolite-based catalyst advances include improved thermal stability and resistance to coke formation. Coke deposition on catalyst surfaces can deactivate them over time, so enhancing stability is crucial for prolonging the catalyst’s lifespan. In parallel, the utilisation of ion exchange methods to modify the zeolite structure can involve incorporating different metal ions or other elements to enhance catalytic properties and improve performance in specific reactions. In addition, introducing mesopores into zeolite structures to enhance mass transfer properties can help mitigate diffusion limitations and improve the catalyst’s performance in large-molecule conversion processes.

Acid sites in zeolites play a crucial role in many refinery processes, and tailoring their strength and distribution can lead to improved catalytic performance while exploring innovative synthesis techniques. These can include microwave-assisted synthesis or template-free methods, to produce zeolites with unique structures and properties that may offer advantages in specific applications. ZSM-5 zeolites are widely used for their catalytic properties in processes such as hydrocracking, isomerisation, and aromatics production.

Despite concerns about the rare earth supply chain, rare earth-modified zeolites improve catalytic performance in various refinery processes while implementing advanced characterisation techniques, such as in situ spectroscopy and microscopy, to gain a deeper understanding of the zeolite-catalysed reactions. Further research and development in the field of zeolite catalysts are ongoing, with the aim of addressing specific challenges in refinery processes and improving overall efficiency. It is advisable to refer to the latest scientific literature, patents, and industry publications for the most up-to-date information on zeolite improvements in the refining sector.

Catalyst pilot plants
Hydroprocessing catalysts focus on improving activity, selectivity, stability, and other factors. For this focus, hydrotreating and hydrocracking technology may benefit from nanostructured catalysts due to their high surface area and reactivity, leading to cleaner fuels and reduced environmental impact. Going as far back as 10 years ago, consideration has been given to the nanostructuring of industrially relevant hydrotreating catalysts as potential hydrogen evolution reactor (HER) electrocatalysts, but additional testing is forthcoming.

The ability to adapt to changing catalyst formulations and testing requirements is essential. Modernised pilot plants should be flexible and easily adjustable to accommodate different types of hydrotreating catalysts and testing conditions. Some aspects of the modernisation of pilot plants for testing hydrotreating catalysts involve advanced reactors, monitoring systems, and analytical tools that provide more accurate and detailed data on catalyst performance.

Modernising pilot plants often involves integrating data analytics tools to process and analyse the vast amount of data generated during testing. Upgrading pilot plants may include improvements to scale-up capabilities, allowing for a more seamless transition from laboratory-scale experiments to larger industrial processes. This is important for ensuring that the catalysts perform consistently across different scales.