Straight talk on hydrocracking catalysis

Nicolaas van Dijk, Global Process Technology Manager, Hydroprocessing, Shell Global Solutions International BV.

Q: Shell Global Solutions works closely with Criterion and Zeolyst; how does this bring value to customers?

Van Dijk: One of the key benefits is that, because we develop the solution in close co-operation with Criterion and Zeolyst, we can provide customers with a combined guarantee that covers both the performance of the process hardware and of the catalyst. Most refiners find that extremely reassuring.

Moreover, it means that we can optimise the solution. We do not design a hydrocracker in isolation and then simply add catalysts; we work closely with our counterparts at Criterion and Zeolyst to match the Shell design with the Criterion catalysts and arrive at a design that works and delivers what the customer wants in terms of product quality, yield, capital cost and so on.

Criterion and Shell have global experience of designing catalyst systems for a variety of feedstocks and in all hydrocracking configurations, including dual-service, once-through and two-stage, and its know-how can be extremely beneficial for customers.

Adarme: The hydrocracker at CNOOC’s Huizhou refinery is a good example of this. The refinery is the first plant in the world designed to process 100% heavy, high-acid, naphthenic crude oil. Obviously, processing VGO originating from heavy naphthenic crudes places special demands on catalysts because these oils contain higher levels of harmful contaminants and it can be especially challenging to achieve the desired high distillate quality.

To mitigate this, Shell Global Solutions and Criterion worked closely to configure a catalyst system and optimise it for the design feed, the desired product slate and the process technology. It worked: all the performance guarantees were met. 

Q: Catalyst performance has improved so much in recent years, is it realistic for refiners to expect next-generation catalysts to continue delivering performance enhancements?

Adarme: Yes, I think so. I do not think we are at the end; in fact, I think we are at the beginning of a new era in terms of catalyst development because new research and development techniques are accelerating product development timelines.

The market is frenetic and furious, and new products are being launched all the time. At Criterion, we have developed an extremely broad portfolio. We have invested a lot in research and development to help us design, develop and commercialise better products, quicker.

For instance, we are using enhanced experimentation techniques that enable us to test 16 catalysts simultaneously. We use this for the development of pretreatment and cracking catalysts. It is a very efficient way to develop new catalyst technologies.

Raul Adarme, General Manager, Hydrocracking, Criterion Catalysts & Technologies.

Q: What is Criterion focusing its research and development on to advance the state of the art of hydrocracking catalysis?

Adarme: Well I can only say so much because, of course, much of it is highly confidential. But I can tell you that we are always looking at ways of improving zeolite systems, metal sulphide functions and catalyst shapes, all aimed at increasing product yields and targeting specific product qualities.

Van Dijk: Yes, and there have been some important developments there recently. For instance, Criterion’s new Advanced Trilobe Xtreme technology is a trilobal catalyst extrudate rather than a cylindrical one, which can increase diesel yield by up to 1.5%. This is because over-cracking occurs if the reactants remain inside the catalyst too long, which reduces diesel yield and creates more undesirable products such as naphtha and gas. So a 50,000-bbl/d hydrocracker can produce up to 750 bbl/d more diesel product simply by changing the catalyst shape.  

Adarme: We have had successes with zeolite manufacturing processes as well; we can now manufacture the zeolite powder such that the zeolites are much more selective. Being more selective means that it is not going to over-crack the feed to gas or liquefied petroleum gas, so you get better selectivity for cracking heavy naphtha and producing jet fuel and diesel. It also offers better middle distillate selectivity than our previous-generation zeolites.

And then there is nanotechnology. Advances in nanotechnology have helped us to optimise the active sites, which led to a next-generation CENTERA® catalyst technology for hydrocracking pretreat.

Q: How do CENTERA products compare with previous-generation products?

Adarme: CENTERA offers the flexibility to help increase run length, process more difficult feedstocks or increase throughput for refiners. CENTERA products are providing performance improvements in the start-of-run, weighted-average bed temperature of up to 14°C lower than previous-generation products.

As always though, we advocate tailored rather than off-the-shelf solutions. We offer a range of CENTERA products including the CENTERA DC-3620 product, which is designed for difficult feeds and high catalyst stability, and CENTERA DN-3630, which is very well suited for hydrocracking units processing feeds containing LCO.

CENTERA technology is the culmination of years of in-depth research. It has a strong legacy built on the innovations of the CENTINEL GOLD and ASCENT platforms along with eight years and nearly 300 cycles of commercial operations for customers around the world.

Q: What steps do you take to ensure that your products remain vitally relevant to refiners?

Van Dijk: It is worth noting that Criterion’s research and development is, in part, informed by the operational feedback received from Shell Global Solutions customers. For instance, we provide a lot of feedback to the catalyst researchers about what to develop; we tell them what our clients need.

Adarme: Indeed, Criterion’s research and development programmes are based on the input we get from our customers through our technical service personnel. That input helps us to define what we need to aim for when we are developing next-generation catalysts.
Generally, refiners in the USA are looking for higher heavy naphtha production and ways to reduce hydrogen consumption. In the rest of the world, it is more about maximising diesel. These aims and objectives are reflected in our research and development programmes.

Van Dijk: There is also a distinct trend for new refineries to be designed for full-conversion hydrocracking to maximise diesel yields. That trend has ramped up over the last couple of years, so, in response to market demand, we have been working with the catalyst development teams to develop a new catalyst specifically for the second-stage service. We are in the process of commercialising this catalyst. The early indications are that it will unlock 6–7% more diesel from a two-stage hydrocracker compared with previous products. 

Q: When should a refiner consider commissioning pilot plant tests?

Van Dijk: Pilot plant testing is most relevant when a refiner is in a distinct situation. For instance, we ran a pilot plant test to verify the catalysts selected for Grupa LOTOS’s hydrocracker because the company was breaking new ground with a DAO feed (see Grupa LOTOS article).

The pilot plants are extremely well equipped and provide substantial insights into how a catalyst will perform at a customer’s facility. Over the years, we have gone to great lengths to ensure that these tests are representative for commercial operation. We do not necessarily have to devise a new pilot plant test for each customer, though. We just have to be aware of the different types of operations and feedstocks that they use, and to have data about them.

Adarme: Once we have determined that a pilot plant test will be constructive, we sit with the customer and discuss the parameters that are important to ensure that we measure them. So, we look at yields, activity, selectivity, product properties and so on.

Q: In summary then, what differentiates the Criterion and Zeolyst products from the other hydrocracking catalysts that are on the market?

Adarme: Well, Criterion is a global leader in hydroprocessing catalysts and Zeolyst is the global leader in commercial and speciality zeolites. But, as we said, getting the best out of a unit also requires a deep understanding of the intricacies of the hardware and the process. That is why it is so important, so valuable, that Criterion and Zeolyst technologists work with the Shell Global Solutions process team and the customer.

Van Dijk: The fact we are both affiliated with Shell is hugely important too. It means we can work together on research and development, seamlessly share computer models and pilot plant testing facilities, co-design units, and join forces on unit performance optimisation and troubleshooting. All of this means that customers can not only adopt leading-edge catalysts from a highly experienced licensor, but they also receive a solution that is tailored to meet their specific challenges.