Developments in reforming catalysts: A never-ending story

D. Bazer-Bachi, Axens, Salindres, France; M. HUTCHINSON, Axens, Princeton, New Jersey (U.S.); P.-Y. LE GOFF, F. LE PELTIER and C. PIERRE, Axens, Rueil-Malmaison, France

Even in the context of the energy transition—with gasoline demand expected to decline—the catalytic reforming process will continue to be a key process in refineries around the world to produce high-octane gasoline and aromatics. High-octane gasoline will meet the needs of high-compression engines and increase the efficiency of the internal combustion engine fleet. Refiners are also being challenged to process more difficult feedstock (including highly paraffinic bio-naphtha), requiring higher severity and improved catalyst formulations. Additionally, some refiners will have a viable alternative to reduce their Scope 3 emissions by extracting the aromatics produced by catalytic reformers to be used as petrochemical feedstock. Hydrogen (H₂) will also remain an important byproduct used in distillate hydrotreaters, especially as more difficult-to-treat bioprocess diesels are mixed in the pool.

The principle means of obtaining an increase in octane and aromatics is the conversion of paraffins and cycloparaffins (naphthenes) into aromatics (FIG. 1).

To achieve these objectives, specialized multi-functional precious metal catalysts are employed in fixed-bed or moving-bed reactors.¹

This article is divided into two sections: the first recalls the initial work performed in the early 2000s to improve the manufacture of continuous catalytic reforming (CCR) catalysts, while the second section is devoted to recent developments in the fixed-bed and CCR catalysts fields. The objective is to highlight that, even if catalyst development in reforming has been ongoing for more than 60 yr, opportunities can be seized to improve unit profitability.

initIal work on catalyst manufacturing optimiZation

To improve the economics, the key point is to mitigate side reactions such as hydrogenolysis and hydrocracking (FIG. 2). To achieve this target, various additives, also called modifiers, have been used over the past few decades.² A key challenge, however, is the scale-up of the laboratory recipe to industrial scale while ensuring a homogenous distribution of the additives throughout the carrier. The impact of this homogenous distribution is described in literature³ and even patented.⁴

As an example of such developments, a significant amount of work was completed in the early 2000s by the authors’ company on the Pt/Sn catalyst formulation to ensure better distribution of tin and its interaction with platinum. FIG. 3 illustrates the close control of the Pt/Sn ratio throughout the catalyst particle diameter for two catalysts, A and B.

As seen in TABLE 1, an improvement in Pt-Sn metallic phase homogeneity (A vs. B) leads to a substantial enhancement in catalytic performance.⁵

The knowledge acquired in the last 20 yr has been applied to improve and develop new generations of reforming catalysts. The impact is discussed below, first for fixed-bed platinum rhenium formulated catalyst and then for CCR type platinum tin catalysts.

Fixed-bed/cyclic catalyst developments

Optimization of the catalyst manufacturing process. Using a microprobe analysis (FIG. 4), it is possible to obtain a two-dimensional picture of the distribution of modifiers on the catalyst particle—higher concentration areas are represented by large red spots, while a more homogenous distribution appears similar to a starry sky with little red spots. The pictures in FIG. 4 taken of catalyst using different production schemes show how the modifier is added can significantly impact the distribution of the modifier and have a direct impact on unit performance, as seen in the pilot test results in FIG. 5.

At start-of-run conditions, the activity improvement is 4°C–5°C, while the de-activation rate is reduced by almost 25%.

Such improvements, for the same catalytic formation, are achieved with a slightly higher selectivity. In reforming, there is typically a tradeoff between activity and selectivity—the higher the activity, the lower the selectivity—but this is not the case with improvement in the manufacturing process. This definitively supports that a factor of paramount importance is the control of the quality of the modifiers distribution all across the carrier, leading to both improvement in activity and selectivity.

Catalyst manufacturing scale-up and formulation optimization. This progression of catalyst scale-up has also provided new opportunities for formulations that initially lacked activity and stability. Indeed, low-activity and low-stability catalysts have a direct impact on unit profitability, as they reduce either the time-of-stream factor or necessitate a reduction in unit capacity. Therefore, such catalysts, even if selectivity was on the high side, could not find their place on the market.

Following the optimization of the manufacturing scheme, it is now possible—while maintaining the same selectivity (orange squares and blue dots in FIG. 6)—to improve the activity by 10°C and improve the stability by decreasing the deactivation rate by a factor of two.

Compared to platinum/rhenium reforming catalyst without modifier, the optimized manufacturing scheme makes it possible to achieve the same stability with a significant selectivity improvement of ~1.6 wt%.

For the same formulation, the activity and stability improvements (linked to the optimized manufacturing scheme) have led to the development of a new family of reforming catalysts to respond more specifically to each customer’s needs. Given that each unit has specific constraints (activity, stability, specific naphtha diet), a one-size-fits-all approach does not allow the customer to maximize profitability.

Impact on economics. Based on these improvements, comparative economic studies were conducted to determine the economic benefit a customer can expect switching to this new generation catalyst compared to the previous catalyst generation. The study was based on a 40,000-bpd reformer capacity for Cases 1, 2 and 4 and for a 44,000-bpd capacity for Case 3. The product valorizations are given in TABLE 2.

Depending on local unit constraints, these new products enable increased capacity, improved catalyst activity and higher unit profitability.

The added value detailed in TABLE 3 is defined in Eq. 1, where the index i considers H₂, fuel gas, liquefied petroleum gas (LPG) and reformate production:

Added value = ∑⁴_i=1 price_i × flow_i – Cost_Naphtha × flow_naphtha          (1)

CCR catalyst developments. For CCR catalysts, the same optimizations in manufacturing and formulation were applied. First, an optimization of the catalytic formulation showed it was possible to achieve higher selectivity for almost all activity compared to the base catalyst, as shown in FIG. 7 with blue dots and grey triangles, respectively.

Similar to the platinum rhenium catalyst used in fixed-bed reformers, some units have margins in terms of activity where the optimization of the catalyst design is of paramount importance. If the activity debit was initially quite large (green diamonds in FIG. 7) following an adjustment of manufacturing, it is possible to maintain the same selectivity while improving the activity by 5°C (green diamonds and orange squares in FIG. 7).

As with any CCR catalyst change, the propensity for coke production must be considered. For the latest generation catalyst, a slight increase in coke make is projected and should be fully compatible with a unit over-design coke burning capacity—this is particularly true considering the high hydrothermal stability of these catalysts, which allow the regenerator to operate at higher oxygen content at the burning inlet of the regenerator with minimal impact on the surface area loss.

In some cases, units running at lower-than-design severity and non-continuous regenerator operation can take advantage of this slight increase in coke make to resume continuous regenerator operation.

Coke production vs. the Base case for the same operating conditions and time on-stream is shown in TABLE 4.

Based on these improvements, considering the same basis as those of TABLE 2, significant economic benefit can be achieved (TABLE 5).

As shown in FIG. 8, it is ultimately possible to fine-tune catalyst formulation to unit constraints (coke burning capacity and maximum operating temperature).

In addition to these selectivity improvements, the higher H₂ production has a direct impact on CO₂ emissions. Presently, the main source of H₂ comes from steam methane reforming (SMR)—for each ton of pure H₂, 8 t–12 t of CO₂ are produced, leading to the grey hydrogen classification.⁶

TABLE 6 considers a 50,000-bpd reforming unit to demonstrate the CO₂ emissions reduction linked to the reduction of grey hydrogen importation. As a result, for units having the margin for reduced activity, this generation of new catalyst also leads to a reduction in CO₂ emissions.

Takeaways. Historically, reforming catalysts were based on platinum, platinum rhenium or platinum tin on chlorinated alumina.⁷ To increase the selectivity of these catalysts, modifiers are added by certain manufacturers to improve unit profitability by increasing selectivity while sacrificing catalyst activity.⁸ An additional side effect of using these modifiers is a more complex manufacturing scheme. After the optimization of the manufacturing scheme, it is possible to unlock this typical selectivity/activity trend by improving activity and/or selectivity without offsetting the other.

Moreover, these process optimizations make it possible to reconsider the use of some old high-selectivity formulations, which were limited by low stability and low activity. These R&D activities and manufacturing improvements allow the catalyst to be fine-tuned, depending on customer constraints, by moving away from the one-size-fits-all approach. HP

LITERATURE CITED

1. le Goff, P. Y., W. Kostka and J. Ross, Springer Handboook of Petroleum Technology, 2nd Ed., Springer, New York, 2017.
2. Jahel, A. N., V. Moizan-Baslé, C. Chizallet, P. Raybaud, et al., “Effect of indium doping of y-alumina on the stabilization of PtSn alloyed clusters prepared by surface organostannic chemistry,” Journal of Physical Chemistry, 2012.
3. Avenier, P., D. Bazer-Bachi, F. Bazer-Bachi, C. Chizallet, et al., “Catalytic reforming: Methodology and process development for a constant optimisation and performance enhancement,” Oil & Gas Science and Technology, 2016.
4. Cauffriez, H., F. Le Peltier and E. Rosenberg, U.S. Patent No. 6.451.199.
5. le Peltier, F., J. M. Devès, O. Clause, F. Kolenda and N. Brunard, U.S. Patent No. 6.511.593.
6. Katebah, M., M. Al Rawashdeh and P. Linke, “Analysis of hydrogen production costs in steam-methane reforming considering integration with electrolysis and CO₂ capture,” Cleaner Engineering and Technology, October 2022.
7. Antos, G. and A. M. Aitani, Catalytic Naphtha Reforming, 2nd Ed., CRC Press, 2004.
8. Ross, J., J. Lopez and P. Y. le Goff, “Redefining reforming catalyst performance: High selectivity and stability,” Hydrocarbon Processing, September 2012.

DELPHINE BAZER-BACHI is Development and Industrialization Team Manager, Industrial Operations Business Division, for Axens. She began her professional career in 2005 as a Research Engineer at IFPEN. She acquired 10 yr of R&D experience in the field of heterogeneous catalysis, with a focus on inorganic chemistry and carrier shaping applied to various topics such as hydrocracking, biodiesel, separations and reforming. In 2016, she joined Axens as a Development and Industrialization Engineer and is in charge of the development of different catalysts and their industrialization in Axens industrial sites, with a specialization in reforming catalysts and carriers (alumina synthesis, shaping and catalyst formulation). Dr. Bazer-Bachi holds an engineering degree from the École Nationale Supérieure des Industries Chimiques in Nancy (ENSIC) and a PhD (chemical engineering) from Université de Lorraine.

MATTHEW HUTCHINSON is Senior Technology Manager, Gasoline and Petrochemical Technologies, for Axens. He brings more than 25 yr of refining experience to his current role at Axens, where manages the Reforming and Aromatic Technology team. In this role, his group is responsible for process licensing (grassroots and revamps solutions) and technical catalyst support, projections and technical service. Hutchinson has played a key role in the North American reforming support, development of improved reforming internals and implementation of Connect’In, Axens’ digital monitoring solution over the last 7 yr. He graduated from Cornell University with a BS degree in chemical engineering.

PIERRE-YVES LE GOFF is Global Market Manager Reforming and Paraffin Isomerization, Commercial Business Division, Commercial Strategy and Customer Marketing Department, for Axens. He began his professional career in 1995 as a Research Engineer at Rhone Poulenc in France, where he acquired extensive R&D experience in a variety of programs with major emphasis on inorganic synthesis and carrier shaping. He joined Axens in 2000 as a Technical Manager for reforming and naphtha hydrotreating applications. After several years in that position, Dr. le Goff joined the Technology Development and Innovation department, where he was in charge of mainly R&D projects in the field of reforming and aromatics. He was appointed to his current position at the end of 2018, and is now responsible for the strategy and development of technical and commercial departments in connection with R&D. Dr. le Goff holds an engineering degree from the École de Chimie de Mulhouse, an MBA from Université de la Sorbonne in Paris, and a PhD from Université de Haute-Alsace.

FABIENNE LE PELTIER is Product Development Manager, New Development and Transformation Business Division, for Axens. She began her professional career as a Research Engineer at IFPEN in the field of heterogeneous catalysis, specializing in metallic supported catalysts for hydrogenation, dehydrogenation and reforming applications. She joined the Axens Technical Service group in 2001 as Technical Advisor, and created a laboratory network to organize spent catalysts and petroleum products analysis and an analysis database to support technical service engineers in their troubleshooting activities. In 2013, Dr. le Peltier joined the New Development and Transformation Business Division, where she has also been involved in the field of new product development and has set up various characterization methods of catalysts. Dr. le Peltier holds an engineering degree from the École de Chimie de Rennes, and a PhD in petroleum science from the Université de Paris VI.

CHRISTOPHE PIERRE is Reforming Product Line Manager, Gasoline Product Line Technology and Technical Support Business Division, for Axens. He joined Axens in 2002 as a Process Engineer in the engineering department and moved later as Project Manager for reforming and gasoline projects. Pierre joined the technology group in 2007 and was in charge of reforming and isomerization technologies related to gasoline pool problematics. In 2014, he became Technology Team Manager in charge of aromatics proposals, and then gasoline proposals. In 2022, he was appointed as Reforming Product Line Manager in the Gasoline Product Line Technology and Technical Support Business Division. Pierre holds an engineering degree from the École Nationale Supérieure des Industries Chimiques and was post-graduated from IFP school.