IsoTherming® Lube & Wax Hydrotreating Technology*


• Lower total capital investments
• Lower operating utilities
• Longer catalyst life
• Higher catalyst efficiency which results in smaller reactors and less catalyst volume resulting in less cost to the refiner
• More isothermal reactor operation which results in better yields and less light ends make
• When added to an existing hydrotreater increased hydrotreating capacity over current operations and longer catalyst life in existing reactor

The IsoTherming® technology developed by Process Dynamics was first commercialized in 2004 in a western U.S. refinery. The first application was making Ultra Low Sulfur Diesel (ULSD) from a feed stream contain 60% straight run diesel and 40% LCO. This unit has now been in successful operation for over 12 years. Together with DuPont, twenty-two IsoTherming® technology hydrotreating/hydrocracking units have been placed into operation worldwide.
This technology uses a novel approach to introduce hydrogen into the hydrotreating reactor that allows much higher catalyst efficiency than conventional hydrotreating reactors. The IsoTherming® technology hydrotreating reactors operate in a liquid full mode in lieu of a trickle bed mode. Reaction rates in typical hydrotreaters are limited by mass transfer of the hydrogen from the vapor phase into the liquid where the reaction occurs. The IsoTherming® technology hydrotreating process has removed the mass transfer limitation and operates in a kinetically limiting mode since hydrogen is delivered to the reactor in the liquid phase as soluble hydrogen. Complete catalyst wetting is constantly achieved.

Many of the reactions that take place in hydroprocessing are exothermic and as a result heat is generated in the reactor. In conventional reactor systems, this requires high volumes of recycle gas to quench as well as multiple catalyst beds. In the IsoTherming® technology process, treated oil is recycled back to the inlet of the IsoTherming® technology reactor. This recycle stream is used to deliver more hydrogen to the reactor but also acts as a heat sink and results in a more isothermal reactor operation resulting in less light ends make.

One of the biggest problems with hydroprocessing is catalyst coking. Cracking often takes place on the surface of the catalyst. If the amount of hydrogen available is not sufficient, cracking can lead to coke formation and deactivate the catalyst. In the IsoTherming® technology process, coking is dramatically reduced because there is always enough hydrogen available already in liquid solution. This will lead to a much longer catalyst life. Catalyst life of 4 years has been achieved in many of the current hydrocracking operating units. The process is designed to use conventional, off-the-shelf catalysts.

Since the hydrogen is delivered to the IsoTherming® technology reactor in the liquid phase no recycle gas system is required resulting in a dramatic reduction in capital cost. Hydrogen is delivered to the IsoTherming® technology reactor by recycling hydrotreated product which acts as an inert hydrogen carrier. Comparing the horsepower of the IsoTherming® technology recycle pump to the horsepower of the recycle compressor which is no longer needed results in substantial utility savings as well.

The technology can be installed as a grass roots unit or in a pretreat configuration. If there is an existing hydrotreater, an IsoTherming® technology reactor can be installed as a simple pre-treat reactor ahead of the existing conventional reactor(s). The pre-treat reactor does most of the hydrodesulfurization leaving less work for the existing conventional reactor, which now operates in a polishing mode. The mass transfer limitation of the conventional trickle bed reactor is no longer a constraint due to the fact the IsoTherming® technology reactor has already transferred the bulk of the hydrogen to the oil. Because of this, catalyst deactivation due to coking in the conventional reactor is drastically reduced.

The capacity of an existing unit can typically be increased substantially by adding an IsoTherming® technology reactor ahead of the existing trickle bed reactor. Expanding an existing unit in this fashion is less than 50% of the cost of expanding the trickle bed system already in operation.


The first commercial application of IsoTherming® technology has been in continuous operation since 2004. Together with DuPont, IsoTherming® technology has been licensed in more than 20 applications around the world, and has been applied to ULSD, kerosene hydrotreating, mild hydrocracking, waxes, and lubes. Existing IsoTherming® technology units range in size from 5,000-78,500 barrels per day of feed.

*The trademark IsoTherming® is licensed from DuPont.