Jan-2025

Hydrocracking a wider variety of feedstocks while reducing energy costs (NARTC 2025)

Refinery hydrocracking projects are expected to grow significantly through 2025, with worldwide capacity projected to reach almost 15 million bpd.

Rene Gonzalez
Editor, PTQ

Article Summary

Several large-scale hydrocracking units are under development or planned, as refiners use these units to crack aromatic ring compounds into gasoline, diesel, and jet fuel.

Other refiners are planning to leverage hydrocracking to produce petrochemical feedstocks such as naphtha, increase opportunities for processing bio-based feedstocks to produce renewable diesel (RD) and sustainable aviation fuel (SAF), as well as process plastic waste-derived pyoils to polyolefins.

The industry has a mandate to expand hydrocracking capabilities to capture margin upcycles. The hydrocracking of macromolecular polyolefins (like polyethylene, polypropylene, and styrene) capable of monetising new feedstock sources, such as plastic waste to value-added chemicals, on a practical scale, will be discussed in PTQ throughout 2025 (see Figure 1).

Catalyst trends
Hydrocracking catalyst development is driven by evolving feedstock challenges, stricter environmental regulations, and the growing need for higher conversion efficiencies and quality products, such as F76 Naval Distillate Fuel, which meet MIL-DTL-16884 specifications (free of impurities like heavy metals and sulphur compounds that could harm engines).

Against this backdrop, key trends in hydrocracking catalysts include advanced zeolites, bimetallic and multimetallic catalysts, feedstock flexibility, and integration of nanotechnology. Zeolites with tailored pore structures enhance selectivity for specific product ranges (for example, maximising middle distillates free of impurities like heavy metals and sulphur compounds).

Additional efforts are focused on zeolites with improved hydrothermal stability to withstand high temperatures and feedstock water content, such as with biomass. Zeolites like ZSM-5 and beta-zeolites can be modified to optimise performance under various process conditions. While bimetallic combinations (like Ni-Mo, Ni-W, and Co-Mo) are well established for hydrogenation activity and sulphur removal, customised catalysts with tunable metal loadings are being developed to handle diverse feedstocks.

Nanotechnology is used to create supports with uniform pore size and high surface area, leading to improved catalyst dispersion and activity Metal nanoparticles are employed for their superior catalytic properties compared to bulk materials.

A longer catalyst lifespan has always been an important objective, as it reduces coking and metal fouling, for example, leading to extended catalyst life and reduced downtime. In parallel, better regeneration methods are being implemented to restore catalyst activity effectively.

Petrochemical integration
Refineries are optimising hydrocracking units to produce naphtha and other feedstocks for petrochemical processes, such as for ethylene crackers and aromatics production. For example, research around hydrocracking of macromolecular polyolefins to accelerate the upcycling of plastic wastes to value-added fuels and chemicals on a practical scale is ongoing. However, the industry may face higher investment challenges as sceptics argue that between now and 2050, plastics in landfills are expected to grow almost 2.5 times higher than plastics recycling.

Digitalisation and optimisation
Refineries are increasingly adopting AI, machine learning, and real-time monitoring to optimise hydrocracking operations, enhance catalyst performance, and minimise energy consumption. AI algorithms analyse real-time operational data to optimise critical variables like temperature, pressure, and hydrogen-to-hydrocarbon ratios, ensuring maximum yield and efficiency.

Predictive models help identify optimal operating conditions for feedstocks with varying properties, while machine learning (ML) models monitor equipment health, such as reactors and compressors, to predict failures or maintenance needs before they occur. AI models analyse the properties of crude oil and other feedstocks to predict their performance in the hydrocracking process, enabling better feedstock blending and selection strategies. Additionally, AI-driven simulations predict the yield of desired products, such as diesel, jet fuel, or naphtha, based on feedstock and operating conditions.

AI can also assist in designing new catalysts by simulating molecular interactions. AI models help refineries minimise energy consumption by identifying inefficiencies in heat exchangers and other systems. Integration with digital twin models allows real-time energy tracking and optimisation.

Biomass and co-pyrolysis
Hydrocracking of pyrolysis oil derived from plastic waste has been extensively studied for its potential to produce high-value products, such as gasoline, diesel, and chemicals. A few notable insights from the hydrocracking of pyrolysis oils have benefited from innovations in reactor designs, like fluidised beds or conical spouted beds, improving scalability and efficiency. This allows for better conversion of mixed or contaminated waste plastics into usable hydrocarbons. Additionally, acid scavengers like calcium oxide can be used during processing to address issues such as chlorine content in the feedstock.

Combining biomass with plastic waste in pyrolysis processes and subsequent hydrocracking can improve the overall yield and quality of the output. This method leverages the carbon-rich content of both feedstocks to produce valuable liquid hydrocarbons and hydrogen, which can further reduce dependency on fossil fuels. These studies suggest that hydrocracking of pyrolysis oil is at the precipice of promising pathways for converting waste materials into highvalue fuels and chemicals, but not without significant challenges.

A few of these challenges include the high oxygen content of biomass-based feedstocks, often in the form of organic acids, alcohols, and aldehydes. These compounds can create acidic environments that corrode hydrocracking reactors, pipelines, and other processing equipment. Acidic corrosion can lead to pitting, loss of material integrity, and critical component failures, especially when high temperatures and pressures exacerbate the effects.

Pyoils and other biomass-based feedstocks contain significant amounts of water. When processed at high temperatures, water can enhance hydrolytic reactions and lead to corrosion of carbon steel and even stainless steel components. Biomass feedstocks may include chlorine from biomass or residual salts. Chlorine and sulphur compounds can form hydrochloric and sulphuric acids during processing, leading to severe corrosion. These impurities require feedstock pretreatment, such as washing or catalytic upgrading, to reduce corrosive agents prior to hydrocracking.

Overlapping concerns
The common denominator among the wider variety of unconventional feeds under consideration is their hydrogen intensity and improved energy efficiency. Catalyst poisoning and fouling have always been a big concern with any type of hydroprocessing operation. Metal contaminants and particulates in biomass feedstocks can poison hydrocracking catalysts, leading to inefficiencies.

Some contaminants also deposit on reactor walls, creating hotspots and localised corrosion, requiring frequent catalyst regeneration or replacement and advanced filtration systems. In summary, it is anticipated that hydrocracking will provide promising pathways for sustainable fuel production and high-margin petrochemical feedstocks. However, it is essential to address these bespoke challenges to ensure operational reliability and longevity.

This short article originally appeared in the 2025 NARTC Newspaper, which you can VIEW HERE