### Advanced Catal y st T echnol ogy and Appl i c ati o ns for Hi gher Qual i t y Fuel s and L ubes
J. S. Beck, T. F. Degnan, M. C. Kerby, and D. O. Marler

ExxonMobil Process Research Laboratories 1545 Route 22 East Annandale, New Jersey 08801

Introduction Cataly sts are among our most powerful tools for creating value while m eeting the challenges of the petroleum and petrochemical industries [1]

. ExxonMobil has c ontinued its long standing tradition of apply i ng industry

- leading cataly s t technology to enable the conversion of complex molecules in crude oil selectively and efficiently into valuable products needed in fuels, lubricants, and chemicals. The merger of Exxon and Mobil brought together a unique sy nergy of m e tal oxide and zeolite cataly s is expertise and ExxonMobil continues to be an industry pacesetter in the broad application of cataly s t technology

. An overview of our active m a terials platform s will be reviewed. Em phasis will be given to how zeolitic, m e soporous, and m e tal oxide cataly s ts are discovered, develope d, and com m e rcially im plem ented to m a nufacture higher quality fuels and lubricants within ExxonMobil. Only through a fundamental understanding of how cataly s ts behave at the molecular level, can innovations in new cataly s t platform s continue. In order to accelerate the pace of cataly s t innovation, ExxonMobil is exploiting the use of high throughput experim e ntation (HTE) to more rapidly discove r and im plem ent new cataly s t technologies that are critical for future advances. To this end, ExxonMobil Research and Engineering Company and Sy my x Technologies, Inc. have entered into a mu lti-y ear technology alliance focused on using HTE to enhan ce downs treamand chem icals R&D activities.

ExxonMobil Cataly st Platforms and Applications Other than a few purely therm a l proces s e s , cataly s ts are us ed in alm o s tall refining and chem ical proces s e s

. Cataly s t s accelerate reactions and lower energy require ments while also improving value by selectively making the desired pr oducts. We continue to design a broad array of cataly s t platfo rm s ranging from s h ape s e lective zeolites to produce world class lubricants, to high activity m e tal oxide cataly s ts to manufacture low sulfur transportation fuels. ExxonMobil’s capability spans across the entire cataly s t pipeline from the discovery of new cataly s ts to commercial implementation. A strong fundame ntal science base drives the discovery of new cataly s t sy stems. Through our internal knowledge of desired hy drocarbon transformations, we can match the molecule size and conversion needs to cataly s t design. In the development phase, the m o st viable cataly s t is selected and a process initiated to find a cos t effective preparation route for the cataly s t of choice. W e then s e t a path to s cale-up the cataly s t, which could include internal manufacture or joint work with a cataly s t vendor. Finally
, we
com m e rcialize the cataly s t with the objective to apply it as broadly as possible across our refinery circu it. This feedback loop provides critical performance information about the performance of the cataly s t and allows us to further identify and develop next generation cataly s t s y s t em s

.

Z e olite Catalysts. Zeolites are an im portant class of m o lecular

s i eves and are us ed to collect, s e parate, and trans f orma wide range of organic m o lecules [2]

. They are cry s talline alum inosilicate fram e works com pos ed of tetrahedral s ilica and alum inum atom s linked by oxy gen atoms, which can be sy nthesized into a variety of pore sizes and shapes. Zeolite discovery is a com p lex science. Com ponents such as silica, alum ina, and an organic tem p lating agent, which provides the s h ape of the m a terial, are com b ined in a controlled pH and tem p erature environm ent to form the cry s talline product. The organic template is then removed through calcination. This leaves behind the cry s talline zeolite fram e work with a pore size that matches the organic temp late. A significant number of experim e nts (100’s-1000’s) are require d to ‘m ap’ the sy nthesis space. Zeolites can be uni-dim ensional or mu lti-dim e nsional and exist in a wide as s o rtm e nt of m o lecular s i zes , s h apes , and inters ecting channels (Figure 1). Unique combinations of pore size, shape, and dim e nsionality can provide a wealth of new zeolites. ExxonMobil has sy nthesized well over 50 unique zeolite structures.

Z S M- 23 ( M TT) 1- D i m e n s i onal 10R 4. 5 x5

. 2 ( Å ) ZS M-3 5 (FE R ) 2

- D i me nsi ona l 10 R 4. 2 x 5

. 4 ( Å ) 8R 3. 5 x 4

. 8 ( Å ) In te r s ec tin g 10 R- 8R MC M- 68 3

- D i m e nsi ona l 12 R 6. 5 x 6

. 8 ( Å ) 10 R 5. 1 x 5

. 5 ( Å ) In te rs ec t i ng 12 R- (2) 1 0 R Figure 1. Zeolites can be form ed in a variety of m o lecular sizes and

s h apes

.
W ith this array of zeolitic m a terials, it is possible to tailor the cataly s t to performthe des i red reacti ons at high rates and selectivity

. The ability to m a tch the size of the m o lecule to the size of the zeolite or molecular sieve is called “shape selectivity ” in which ExxonMobil is a leader (F igure 2).

Zeol i t e Y

ZS M

- 5 Po r e Si z e Å

40 60 80 10 0

5 10 20

G aso l i n e G a so i l R esi d s 10 0Å

1 00Å Po r e S i z e ( 20- 100+ Å ) Ads o r p t i on , S e pa r a t i o n C a t a l y t i c C onver si on of L a r g e M o l ecu l e s ZS M 5
- MC 4 1 M-

MC - 4 1

M

Figure 2. Us e of s h ape s e lectivity to des i gn cataly s t pores for selective conversion of molecular ty pes.
Today
, the shape selectivity concept is the basis for ~20 commercial processes with annua l hy drocarbon throughput in excess of 70 m illion m e tric tons per y ear. For exam ple, cataly tic cracking, a key refinery process used to produce gasoline and diesel utilizes zeolite-Y, which selectively cracks heavier vacuum gas oil

m o lecules. ZSM-5, a sm aller pore zeolite, can be added as a cocataly s t to the cat-cracker to prom ote the s e lective form ation of propy lene, a valuable chemical product. Another opportunity for exploiting shape selectivity concepts lies in the m odification of

m e soporous m o lecular sieves for reaction or separation of larger molecules. Researchers have functionalized the pores of MCM-41 to

s e lectively ads o rb low concentrations of m e tals s u ch as Hg and Ag while excluding other metals [3, 4]

. The zeolitic cry s tal is formulated into a finished cataly s t through the addition of various com ponents such as binders (e.g. silica, alum ina, zirconia, titania), m odifiers, m e tals and m e tal oxides (e.g.



### Prepr. Pap.-Am. Chem. Soc., Div. Fuel Chem. 2004 , 49 ( 2 ), 507Pt, Pd, Ni, Co, Mo). These compone nts can be added to optimize the finished cataly s t’s acidity , m e tals activity , porosity , and phy sical integrity

. One key application of shape selectivity is ExxonMobil’s selective cataly s ts dewaxing tec hnology . Dewaxing rearranges the

s t ructure of prim arily s t raight chain m o lecules to ens u re they have the correct flow properties at the des i red tem p eratures . The M S DW

2 cataly s t technology is a m e diumpore zeolite which applies shape selectivity
, proper control of acidity , and a m e tal driven hy drogenation-dehy drogenation functi on to selectively convert or ‘dewax’ the s t raight chain m o lecules to a s lightly branched

m o lecules as it enters the zeolite pore. More bulky or branched

m o lecules
, which already have beneficial lubricant properties
, are excluded from entering the zeolite pore. Thus, this cataly s t technology only works on the molecules that need to be converted.

Metal Oxide Catalysts . Another important class of cataly tic materials that are widely used in the refining industry are metal oxides

. Thes e m a terials
, which ar e ty pically mixtures of CoMo or NiMo oxides on silica-alumina suppor ts, are primarily used in key refinery processes called hy droproce ssing. This technology uses the cataly tic addition of hy drogen to selectively remove sulfur and nitrogen from various refinery streams to produce low sulfur gasoline and diesel. More hy drogen intens ive hy droprocessing applications can also reduce other components su ch as olefins and aromatics. The prime contributor to sulfur in the gasoline pool is from the cat-cracking unit. W h ile it is possible to hy drotreat the sulfur to very low levels, cat naphtha also cont ains a considerable amount of valuable olefins, which are high in octane. Thus, the challenge is to selectively rem ove sulfur while m i ni mizing the saturation of olefins. This is particularly an issue for higher sulfur cat naphthas. ExxonMobil’s SCANfining technology [5] utilizes a proprietary CoMo cataly s t, jointly developed with Akzo Nobel, to selectively reduce the cat naphtha sulfur while minimizing the saturation of high octane olefins (Figure 3).

Figure 3. ExxonMobil’s SCANfining technology selectively removes sulfur while minimizing octane loss.

The CoM o s y s t emis characterized by high m e tals dis p ers i on with special attention given to the support-metal interactions. SCANfining II , is even m o re selective particularly for higher sulfur cat naphthas. SCANfining has been rapidly com m e rcialized and will be used in 30 units worldwide to manufacture low sulfur gasoline. A new generation of ultra-high activity cataly s ts for nitrogen and sulfur rem oval was recently discovered by ExxonMobil and jointly developed with Akzo Nobel. This cataly s t sy stem called NEBUL A TM is unique in that it is a bulk mixed metal oxide, which maximizes the number of active s ites per volume of cataly s t [6]

. NEBUL A TM has shown very high hy drodesulfurization and hy drodenitrogenation activities com p ared to conventional cataly s ts (F igure 4). This perform ance advantage enables the refiner to produce ultra low sulfur diesel in existing units. NEBUL A TM has been com m e rcialized in a num ber of distillate hy drotreating and hy drocracking applications.

0 100 200 300 400 500 600 700 800 900

1950 1955 1960 1965 1970 197 5 1980 1985 1990 1995 2000 2005
Y earHDSActivity N e bul a

C o M o Al u m i n a

Figure 4. NEBUL A TM cataly s t technology represents a step change in Hy droprocessing cataly s ts.

Fu tu re Ad van ces in Catalys i s Cataly sis will continue to play a crucial role in the petroleum and petrochem i cal industries. Fuel and lube com positions are expected to evolve in response to environmental legislation and advanced engine design. In a ddition, petroleumfeedstocks will becom e heavier and sourer with tim e. This will require future cataly s ts, which are higher in activity and selectivity , m o re poison tolerant and stable for longer periods. ExxonMobil is com m itted to accelerate the pace of innovation and delivery through the use of HTE. ExxonMobil and Sy my x Technologies, a leader in the development and application of highspeed m a terials research m e thods, have form ed a technology alliance focused on the application of HTE technology across ExxonMobil' s downstream and chemical portfo lio. Im plem entation of HTE

m e thods will enhance ExxonMobil’s core com p etency in cataly s t research and developm ent. This alliance includes high throughput cataly s t sy nthesis, characterization, and evaluation tools coupled with an informatics platform to more rapidly discover and implement future cataly s t s y s t em s

.
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. E

. ; Dwy er , F. G. Shape Selective Catalysis in I ndustrial A pplications
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, New Yor k
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(4 ) Fen g , X., Frywell, G.E., Wan g , L.Q., Kim
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, 923 (5 ) Riley, K. L.; Kauf m a n, J. L.; Zaczepin ski, S.; Desai, P. H.; Mayo, S. W. Akzo Nobel Catalyst Symposium, Vol. G-3
, 1998, 1. (6) Meijburg G.,Brevoord E., Plantenga F., May o S., Inoue Y., Fujita K., Lewis W., Sap r e A., NEBULATM for Hydrocracker Pretreat Operations
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### Prepr. Pap.-Am. Chem. Soc., Div. Fuel Chem. 2004 , 49 ( 2 ), 508