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PTQ Annual Catalysis Supplement
Michael Cleveland, Honeywell UOP
Stunning technological advances have occurred since UOP introduced catalysis to the refining industry in 1933. It graduated the science of refining from a series of processes governed by pressure, temperature and time, to one where catalysts could be employed to perform specific functions to break and rearrange molecular bonds to make predetermined products. As catalytic science became more sophisticated, catalysts could be engineered to perform those functions more selectively and efficiently.
By merely coming into contact with a catalyst, hydrocarbon molecules can be induced to break apart, join together, and rearrange themselves into intended new forms. But despite all the achievements in catalytic science in the last 87 years, the industry still has only scratched the surface of what catalysts can do.
Most of the developments in catalysts resulted from the invention of new materials that do not exist naturally. These materials were designed to be manufactured with repeating crystalline structures with advanced properties. For example, acid catalysts were developed with greater acid site density and strength, lower diffusion paths, and other qualities to make them more efficient. Novel metal catalysts featured new nanomaterials, or atomic-level compositions, with superior electronics that gave them new capabilities. All of these developments are the product of highly-developed core competencies in the design of new materials, and the manufacturing expertise to uniformly synthesize them.
While the industry has developed thousands of new materials, including hundreds of new zeolites, a second competency is necessary to scale up production from a few grams in a lab to continuous quantities that may number in the hundreds of metric tons.
Today, much of the development in catalysts focuses on process intensification -- designing catalysts that are more efficient than existing catalysts, or that perform more than one chemical conversions in a single step. This allows them to process more feedstock with fewer and smaller units, requiring less land, steel and energy.
Because catalysts are integral to the process technology, this profoundly improves the economics of refineries and petrochemical plants by reducing their utilities requirements and water use, avoiding production of low-value byproducts, and even allowing them to use a wider range of feedstocks. These processes, enabled by more capable and efficient catalysts, can lower capital requirements and operating costs.
Catalysts also are at the heart of the Refinery of the Future, a framework of asset development and molecule management that helps ensure optimal economic efficiency, profitability and environmental leadership over time. It is an approach to capital investment that is unique to each refinery. Different combinations of technologies are built in carefully timed stages to meet changing market conditions, take advantage of changing feedstocks, and meet evolving regulatory constraints and competitive threats – with the goal of maintaining optimal profitability.
One of the overriding trends in the industry today is the widely forecast peak in global demand for transportation fuels in the mid-2030s, due to the introduction of more fuel-efficient engines and the growing number of vehicles powered by alternative fuels. At the same time, new environmental regulations threaten to strand refining capacity for fuels that do not meet stricter emissions standards.
This has caused many refiners to upgrade their fuels refining capacity while bridging into petrochemicals, where product demand and margins remain strong, due to 4-percent growth in global GDP driven in part by population growth in developing economies.
More efficient processes -- based on more sophisticated catalysts – offer great competitive advantages in terms of operating margins and slate flexibility, with the ability to direct molecules to processes where they can produce the greatest value. The best solutions are catalysts that are designed to operate under these new conditions using existing capital assets. In this sense, they are akin to reprogramming a refinery, in the same way you would install a software upgrade to a computer. The refinery is essentially the same, but now it can do more.
For example, a new catalyst – with some modifications to operating conditions – can change a hydrocracking unit from production of distillate to production of naphtha. With the staged investment of a CCR Platforming unit, the naphtha can be converted into aromatics -- and LPG which, with the addition of a PDH unit, can be the feed for producing olefins.
While existing refineries are investigating these paths, new world-scale refineries already are being built that will convert half or more their feedstock into petrochemicals. In fact, refineries that produce only petrochemicals probably are not far behind.
Where economics favors larger operations, new catalyst designs also make it possible to design larger units with greater capacities. In cases where processes are hydrodynamically limited, a catalyst can be made denser or stronger, or given a more efficient shape or some other property to accommodate greater production capacity, without risking pressure drop, pinning or void blowing.
The design of advanced catalysts today requires advanced characterization techniques, employing electron microscopes to verify the composition of the material and even ensure metals have been properly dispersed. Without the ability to actually inspect what has been created, we can’t know exactly why a new catalyst formulation behaves the way it does.
One of the processes used to selectively convert lower value toluene and C9+ aromatics into benzene and xylene products is the Tatoray process. In this process, toluene is combined with C9 and C10 aromatics and converted to benzene and xylenes in a simple transalkylation reactor system, more than doubling the yield of paraxylene from a given naphtha feedstock.
But to further increase yields of paraxylene from an aromatics complex -- and allow the use of even heavier feeds -- UOP developed the TA-42 catalyst for the Tatoray process. This catalyst employs a true nano-zeolite which is highly stable, active, and selective because the reactions are controlled by mass transfer. The dimensions of the zeolite pores are smaller, giving it more active sites and greater selectivity to the molecules without getting clogged by heavier C9 and C10 aromatics. As a result of its higher activity, yields of paraxylene per unit of energy – and overall processing capacity -- are higher. The ability to scale up this zeolite was made possible by the invention of a new material.
One of the persistent problems with upgrading vacuum residue, or so-called “bottoms,” is the volume of carbon byproduct, or pet coke. Conventional coking converts this residue to naphtha and diesel-range products, but also generate large quantities of low-value coke.
UOP introduced a new slurry upgrading process using MicroCat catalyst. The Uniflex™ MC™ process works by thermal conversion of heavy hydrocarbons in the presence of hydrogen. The stabilized light oil products are used for fuels and as feed for petrochemical manufacturing. Uniflex MC converts more than 95% of its vacuum residue into light vacuum gas oil and distillate which are ideal feeds for an FCC or hydrocracking unit, respectively. These light feeds are more easily converted to distillates and naphtha with less energy intensity than would otherwise be required.
It can easily be integrated into existing refining facilities, and can process even high-sulfur residues and highly aromatic streams such as FCC cycle oils while producing only small amounts of VGO that can be fed to an existing hydrocracker or FCC unit. This is especially consequential as the industry continues to rebalance in the wake of new MARPOL regulations on marine fuels.
UOP also introduced the ULTIMet hydrotreating catalyst, an unsupported VGO pretreat catalyst, to more cost-effectively produce fuels that meet tightening quality specifications. As an unsupported catalyst, it has a higher metals content per unit of volume, making it far more active than a catalyst with an alumina binder. As a result, it improves sulfur and nitrogen removal while raising cetane levels. The catalyst is designed to work in existing units, eliminating the need to build additional reactor space or operate at higher pressures. Utilization benefits from higher feed rates, and there are typically longer periods between catalyst change-outs. For refiners with available hydrogen, an added advantage is the volume swell the ULTIMet process provides.
Because refiners and petrochemical producers are looking for new ways to produce heavy naphtha from diesel and VGO feeds, UOP developed new HC-680/682/685 hydrocracking catalysts that convert VGO, diesel, and light coker gas oil to naphtha, which can be tailored for aromatics production with the new R-364 Platforming catalyst.
Advances in Alkylation
The alkylation process upgrades low-value refinery butanes and olefins to a high-value blend component which helps to offset combinations of gasoline pool vapor pressure, sulfur, octane, aromatic, and olefin content limitations present in today’s gasoline pool.
One of the most significant new catalysts to be introduced in the current period is the ionic liquid catalyst used in the ISOALKY process for production of alkylate. The ionic liquid catalyst is far simpler to handle than conventional liquid acid catalysts. Essentially a salt in liquid state, it is far less corrosive to skin than hydrofluoric or sulfuric acids, eliminating the need for special personal protective equipment required for acid catalysts. Its low vapor pressure allows it to remain a liquid at ambient temperatures, allowing it to drop into a containment basin in the event of a leak, rather than into a vapor cloud. Due to its higher activity and on-site regeneration, far smaller inventories are required for an alkylation unit.
The ISOALKY process produces a higher-octane alkylate – typically 99 RON – allowing more of a lower-octane blend stock to be used to produce 93-octane motor fuels. It operates at lower temperatures than conventional acids and has greater feed flexibility while producing almost no acid soluble oil byproduct. Because it can process C3 to C5 olefins, it eliminates the need for additional reactors to separate these hydrocarbons, and the steel and utilities required to operate them.
A Revolution in Managing Catalysts
Historically, the purchase of a catalyst has been a one-time transaction, where the catalyst provider responds to a customer’s request for proposal with the best possible solution at that time. In the future, catalyst management will become an ongoing transaction based on the achievement of a prescribed outcome where catalyst performance is actively and continuously managed.
The catalyst supplier actively monitors unit performance through connected plant technologies, providing operational recommendations to the customer over the lifecycle of the catalyst. Optimization recommendations are provided proactively and in real time, rather than in periodic health checks, or when a customer suspects performance problems – potentially protecting millions of dollars of production from being lost to underperformance.
While this benefits the customer, it also creates a cost for the catalyst supplier, and this demands a new payment model. Instead of merely purchasing a catalyst and managing its performance, the customer pays on the basis of performance. If the catalyst fails to meet certain performance criteria, the supplier is owed less. But if the catalyst meets – or even exceeds – those criteria, the supplier earns a portion of the additional profit.
Essentially a risk-sharing program, it puts the supplier and the customer on the same side with fully aligned economic incentives. From the supplier’s standpoint, the more successful the customer is, the more the supplier will benefit. Conversely, if the customer suffers, the supplier will suffer equally.
This is a revolutionary paradigm in the refining industry today, but indexing cost to performance is a common model in other industries. Construction projects are guaranteed on-time completion with late financial penalties for delays, shipments of goods are guaranteed for on-time fulfillment also with penalties for late delivery, and investment advisors are compensated on how much their clients profit from their services. In many industries, suppliers are incentivized to reduce costs by sharing a portion of the savings.
This model is most likely to demonstrate recurring economic benefits to the customer over a period of years, as new catalysts are developed and experience with them is gained. It also eliminates periodic capital expense by aligning the cost of the catalyst to production over time. Instead of simply paying for a catalyst, the customer pays only for what the catalyst does.
This model is not for everyone but, perhaps counterintuitively, it is likely to gain traction first with sophisticated operators, or “optimizers” for whom the added benefits and risk sharing are most attractive.
Michael Cleveland is vice president and general manager of Honeywell UOP’s refining catalysts business.