Microporous and Mesoporous Materials 166 (2013) 161166Contents lists available at SciVerse ScienceDirect

Microporous and Mesoporous Materials

journal homepage: www.elsevier .com/locate /micromesoBEA zeolite nanocrystals dispersed over alumina for n-hexadecanehydroisomerization

N. Batalha a,b, S. Morisset a, L. Pinard a,, I. Maupin a, J.L. Lemberton a, F. Lemos b, Y. Pouilloux aa Laboratoire de Catalyse en Chimie Organique, UMR 6503 CNRS, Universit de Poitiers, 40 avenue du Recteur Pineau, 86022 Poitiers Cedex, Franceb Institute for Biotechnology and Bioengineering (IBB), Centre for Biological and Chemical Engineering, Instituto Superior Tcnico, Universidade Tcnica de Lisboa,Av. Rovisco Pais, 1049-001 Lisboa, Portugal

a r t i c l e i n f oArticle history:Available online 3 May 2012

Keywords:BEA aggregationDiffusion limitationsNanocrystalsHydroisomerizationComposite materials1387-1811/$ - see front matter 2012 Published byhttp://dx.doi.org/10.1016/j.micromeso.2012.04.041

Corresponding author. Tel.: +33 (0)5 49 45 39 05E-mail address: ludovic.pinard@univ-poitiers.fr (L.a b s t r a c t

The direct synthesis of BEA nanocrystals was performed on an a-Al2O3 surface, in order to avoid the typ-ical aggregation of the zeolite, which causes diffusion limitations. Two different composite samples, withdifferent zeolite loadings were synthesized and compared with a pure BEA nanocrystals sample (similarsynthesis gel composition). The characterizations showed that both the BEA zeolite sample and the zeo-lite nanocrystals on the composite samples had similar textural and acidic properties. However, throughTEM and SEM characterizations it was possible to confirm not only the smaller occurrence of zeoliteaggregates on the composite samples, but also the existence of completely isolated BEA nanocrystals,indicating the success of the synthesis procedure.The catalytic test results of n-hexadecane hydroisomerization, at 220 C and 30 bar, showed a positive

effect of the decrease in nanocrystal agglomeration on both activity and isomers selectivity. The compos-ite catalysts were 3.5 times more active than the pure zeolite sample and the maximum isomers yieldincreased from 35 to 80 wt.%.

2012 Published by Elsevier Inc.1. Introduction

The FischerTropsch waxes composed, mainly, of linear paraf-fins must be upgraded for liquid fuel or lubricant base oil applica-tions [1,2]. The catalytic dewaxing process, through skeletalisomerization of the paraffins, reduces the pour points, enhancingthe low temperature properties of diesel and lubricating oils [3].The skeletal branching of n-alkanes is achieved using bifunctionalcatalysts containing both metallic sites, for the dehydrogenationand hydrogenation reactions, and acidic sites for the isomerization(and cracking) reactions [3]. Zeolites loaded with platinum or pal-ladium have been widely used for this purpose [4,5]. The olefinsformed from the paraffins through dehydrogenation on the metal-lic sites are protonated on the acidic sites into an alkylcarbeniumion. This ion undergoes skeletal rearrangement and eventually,cracking through b-scission [6,7]. The later is favored as thebranching degree of the carbon chain increases. Consequently, highisomers selectivity is directly linked to low cracking rates.

When the hydrogenating function is highly active, the activityand selectivity will depend on the number, the strength and thelocation of the acidic function [810]. Therefore, a decrease in acid-ity will lessen not only cracking but also the global activity, sinceElsevier Inc.

; fax: +33 (0)5 49 45 37 79.Pinard).the acid step is rate limiting. The zeolite pore structure can alsomodify the activity and the selectivity of the bifunctional catalyst[1,5,1114]. If the geometry and the dimensions of the zeolitespores are such that cracking is suppressed by molecular shape-selectivity, the yield in isomerization is improved substantially[1,5,15]. For instance, PtHZSM-22 (10 MR zeolite, TON frameworkstructure) is very selective for the production of monobranchedisomers [1517]. Indeed, since the reaction intermediates are toobulky to be formed within the ZSM-22 channels the reaction onlytakes place at the pore entrance (pore mouth catalysis) limitingthe formation of monobranched isomers [1517]. Nonetheless,the consequence of this small penetration is a rather low activityof the catalyst [18]. The molecular shape-selectivity obtained withthe ZSM-22 zeolite is lost on similar pore size zeolites with two- orthree-dimensional pore systems, i.e. ZSM-5 and MCM-22. On thesesupports the reaction occurs inside the zeolite channels resultingin high cracking yields. Indeed, the reaction intermediates areblocked inside the channels where they crack after multi-isomeri-zation steps [19]. In order to avoid this phenomenon, Christensenet al. introduced, through disilication, a complementary mesopor-ous system in ZSM-5 zeolites reducing the isomers residence timeinside the zeolite framework and, consequently, limiting cracking[20]. As a result, better acid site accessibility and rapid isomersdesorption outside the zeolite crystal improved both hydroisomer-ization activity and selectivity.

http://dx.doi.org/10.1016/j.micromeso.2012.04.041mailto:ludovic.pinard@univ-poitiers.frhttp://dx.doi.org/10.1016/j.micromeso.2012.04.041http://www.sciencedirect.com/science/journal/13871811http://www.elsevier.com/locate/micromeso

162 N. Batalha et al. /Microporous and Mesoporous Materials 166 (2013) 161166Soualah et al. have shown that PtHBEA (12MR, BEA frameworkstructure) was more active and more selective for the hydroiso-merization of long n-alkanes (n-C14, n-C16) than catalysts basedon MCM-22 or ZSM-5 zeolites [19]. This was explained by a rapiddiffusion of the reactant and reaction intermediates inside thelarge channels of the BEA zeolite. Yet, the PtHBEA catalyst yieldedsignificant amounts of cracked products due to rather strong pro-tonic acidity. Thus, decreasing the zeolite acidity would decreasethe cracking reactions rate. This was confirmed by Merabti et al.,using partially sodium exchanged BEA zeolites, which showed anisomerization selectivity similar to that of ZSM-22 [18]. Nonethe-less, this was achieved with a 75% loss of the BEA zeolite activity,even if the PtNaHBEA (0:7 gn-C16 g

1cat g

1) catalyst remained twotimes more active than PtHZSM-22 (0:3 gn-C16 g

1cat g

1).Like for the ZSM-5 zeolite, the reduction of the isomers resi-

dence time inside the BEA zeolite crystal would positively enhancethe selectivity towards isomerization. Moreover, this approachwould not cause an activity loss. Zeolite nanocrystals are oftenused for this purpose [2124]. However, the BEA nanocrystallitesaggregate into micrometric clusters, more than 1 lm, creating anintercrystalline disordered porous system, which alters the molec-ular diffusion [25,26]. Lima et al. showed that the diffusivity valuesof n-alkanes obtained from zeolite BEA nanocrystals were extre-mely low when compared to those of zeolites with similar poreaperture, e.g. FAU [26]. The authors suggested a possible influenceof extracrystallite diffusion. Thus, in order to improve the catalyticproperties, it is essential to avoid the BEA crystallite agglomerationin order to minimize the isomers residence time inside the zeolitecatalyst. This can be obtained by the direct BEA zeolite germinationon a support, such as alumina [27]. Lovallo et al. have shown thatin the case of nanocrystal zeolites (99.9% purity) was carriedout in a fixed-bed stainless steel reactor under the following

N. Batalha et al. /Microporous and Mesoporous Materials 166 (2013) 161166 163conditions: temperature 220 C; total pressure 30 bar; H2/n-C16molar ratio 20; and WHSV (weight hourly space velocity) between2 and 100 h1. WHSV was changed by modifying the reactant flowrates in order to obtain different conversion values. The reactionproducts were analyzed online by GC equipped with a 50 mCPSil-5 capillary column from Chrompack, with hydrogen as car-rier gas (13 psi) and a FID detector. To avoid product condensationproblems it was necessary to dilute n-C16 in an inert solvent. n-Hexane (Aldrich, >99.9% purity) was chosen as solvent and the feedcomposition was 10 mol.% n-C16 and 90 mol.% n-C6. During reac-tion, none of the catalysts presented deactivation. Before reactionall the catalysts were reduced under hydrogen flow at 450 C for6 h.3. Results and discussion

The samples resulting from the direct synthesis of BEA nano-crystals over an a-Al2O3 surface (HL and LL catalysts) will be com-pared to a pure BEA catalyst in terms of textural, morphologicaland acidic properties. Likewise, the catalytic performances of thesesamples will be evaluated through the n-C16 hydroisomerization.

3.1. Textural and morphological properties

The X-ray diffractograms (XRD) of a-Al2O3, BEA, HL and LL cat-alysts are shown on Fig. 1. The a-Al2O3 and BEA samples presentthe typical patterns of the corresponding phases. On the otherhand, the HL and LL catalyst XRD patterns showed the presenceof both a-Al2O3 and BEA phases. No traces of other compounds,such as c- or h-Al2O3, were observed. Concerning the BEA zeolitephase, a broad peak in the range of 6.58.5 2h indicated the pres-ence of the two isomorphs. The BEA zeolite crystal sizes were cal-culated through the Scherrer equation using the most intense peak,22.4 2h (Miller index 302). The BEA crystallites changed from30 nm on the BEA to 43 nm on both composite catalysts. Finally,through the catalysts XRD patterns it was possible to estimatethe zeolite content on the coated catalysts, by using the X-ray massattenuation coefficient of the pure BEA zeolite and of a-Al2O3. Thezeolite content on the LL and the HL samples was, respectively, 13and 40 wt.%. The zeolite loading observed on the HL was threetimes higher than on the LL and, thus, in accordance with the pro-portion of alumina introduced upon zeolite synthesis, e.g. threetimes lower for the HL sample.

The textural properties of the samples deriving from the N2adsorption are reported in Table 1. The isotherms of all the sampleswere quite similar to those of purely microporous materials, with aplateau from very low relative pressure values (Fig. 2). The meso-pore volume created by the intercrystalline voids was quite low,only 0.08 cm3 g1, which indicated that the nanocrystallites werestrongly agglomerated and that the ultra-micropore volume was5 15 25 35 452

BEA

HL

LL

-Al2O3

Fig. 1. XDR patterns of the samples.equal to the micropore volume. On the other hand, the N2 adsorp-tion results indicated that there was no significant change in thezeolite and alumina textural properties between the pure and com-posite samples, since when considering a zeolite basis the HL andLL samples presented characteristics similar to those of the purezeolite. Likewise, the pore size distribution of the BEA, HL and LLsamples were similar (Fig. 3). Thus, the catalysts textural proper-ties obtained through N2 adsorption confirmed the assumptionmade for the zeolite composition estimation, which consideredthat there was no change in the zeolite nor in the alumina struc-tures between the pure and composite samples, which therefore,supported the composite catalysts zeolite compositions.

Scanning electronic microscopy (SEM) showed differences be-tween the samples textures. As expected according to literature[26], the SEM image of the bare BEA zeolite (Fig. 4A) showed ahigh agglomeration of the zeolite crystals which, despite ofhaving a nanometric size, formed 2.4 lm average size sphericalclusters. On the other hand, on the HL sample, which contained40 wt.% zeolite, the alumina surface was completely coveredwith agglomerated BEA crystallites (Fig. 4B). By opposition, onthe LL sample (13 wt.% of zeolite) only a few BEA clusters couldbe observed (Fig. 4C). Nevertheless, the alumina surface wasfully covered by zeolite crystals, as shown by the Si elementmapping performed on the catalyst surface (Fig. 5), suggestingthe presence of BEA nanocrystals attached to the aluminasurface.

Fig. 6 shows the TEM micrographs of the two composite sam-ples and of the pure BEA sample. The later consisted on BEA nano-crystallites, which, as expected, were strongly agglomerated(Fig. 6A). Moreover, the strong aggregation was already suggestedby the low mesopore volume measured through N2 adsorption.Likewise, the nanometric size of the BEA crystals was in accordancewith the 30 nm determined by XRD. On the composite samples, theoccurrence of isolated nanocrystals could be observed. However, itwas more frequent on the LL sample. The crystallite shapes werecubic, and the crystal sizes were similar to those determined byXRD (43 nm). Moreover, lattice fringes and sharp edges can be seenin Fig. 6B and C, indicating a high degree of crystallinity. The TEMimages also showed that the alumina matrix in contact with thezeolite crystal suffered a restructuration in order to match the zeo-lite pattern. This suggests not only the alumina partial degradationby the zeolite synthesis gel, but also explains why the zeolite crys-tals remained attached to the alumina surface after the ultrasoundtreatment.

3.2. Acidic and metallic properties

The three samples were also characterized by FT-IR spectros-copy, in order to obtain further insight on their acidic and struc-tural properties (Table 2). The framework Si/Al ratios, estimatedfrom the zeolite structure bands (4501250 cm1) [33], wererather low for a BEA zeolite, e.g. 1113 (Table 2). In the OH regionof IR spectra, the BEA zeolite presented four bands (Fig. 7). Themost intense band, at 3740 cm1, corresponded to the externaland internal silanol groups [35] and was, consequently, in agree-ment with the small crystallite size of the zeolite (30 nm). Thethree other less intense bands were ascribed, respectively, to bridg-ing OH groups (3608 cm1) [35], to hydroxylated monomeric andpolymeric extraframework Al (EFAL) species (3663 cm1) [35,36]and to hydroxylated monomeric EFAL species and framework de-fects with Lewis acidity (3782 cm1) [37]. These bands were alsopresent both on the HL and LL catalysts (Fig. 7), and their intensi-ties (normalized at the zeolite content) were close to those of thezeolite alone. Nonetheless, the appearance of one additional bandat 3510 cm1 (Fig. 7) was observed on the composite samples. Thisband, not typical of the BEA zeolite or any alumina phase, was

Table 1Textural properties of BEA, a-Al2O3 and composite catalysts.

Catalyst Zeolite loadinga (wt.%) Crystal sizeb (nm) SBET (m2/gcat) Sext (m2/gcat) Vmesopore (cm3/gcat) Vmicroc (cm3/gcat) VUltra-microd (cm3/gcat)

BEA 100 30 671 56 0.08 0.26 0.262HL 40 43 270 (666*) 21 0.03 0.11 (0.27*) 0.11 (0.26*)LL 13 43 92 (663*) 8 0.01 0.04 (0.28*) 0.04 (0.27*)a-Al2O3 0 94 6 5 0.01 0 0

a Estimated from the XRD pattern.b Calculated through the Scherrer equation.c Obtained from the DubininRaduskevitch method.d Obtained from the t-plot method.

* per gzeolite.

0

50

100

150

200

250

300

350

400

0 0.2 0.4 0.6 0.8 1

Vad

s(c

m3 .

g-1 )

Relative pressure

BEAHLLL

Fig. 2. Nitrogen adsorption isotherms of the samples.

0

0.005

0.01

0.015

0.02

0 2 4 6 8 10

Por

e vo

lum

e (c

m3 .

g-1 )

Pore radius (nm)

BEAHLLL

Fig. 3. Pore size distribution of the samples.

Fig. 4. SEM images of the samples: (A) BEA zeolite; (B) HL; (C) LL.

164 N. Batalha et al. /Microporous and Mesoporous Materials 166 (2013) 161166ascribed to a hydroxyl group formed on alumina during synthesis.However, the acidic properties of this hydroxyl were weak since nointeraction with pyridine was observed.

On the three catalysts, the number of Brnsted and Lewis acidsites was determined by pyridine desorption at 150 C. When con-sidering the composite catalysts on a zeolite content basis, theBrnsted sites density was in the same range as that of the BEAzeolite, around 600 lmol g1. These rather high values are inagreement with the low Si/Al ratios observed on the samples. Onthe other hand, the number of Lewis acid sites, on a zeolite basis,was 3.5 higher on the LL and HL catalysts than on BEA zeolite. Thissuggests that during the zeolite maturation the high crystallinealumina was partially decomposed by the high pH synthesis gelsolution (pH = 13), which led to the formation of both Lewis acidsites and the new hydroxyls group, observed on the IR spectra.On the HL and LL catalysts, the platinum introduced by ion ex-change was located both on the alumina support and on the zeo-lite, even if, the TEM micrographs showed that the major part ofmetal was located on the zeolite. The average platinum particlesize, however, was similar on all the samples (Table 2).

In conclusion, the acidic and the metallic properties were simi-lar on the HL, LL and BEA bifunctional catalysts. Consequently, themain difference between the samples concerned the agglomera-tion of the zeolite nanocrystals: strong on the BEA, absent on theLL catalyst.

Fig. 5. EDX mapping of the Si element on the LL sample surface.

Fig. 6. TEM images of the samples: (A) BEA zeolite (30,000); (B) HL (120,000);(C) LL (200,000).

34503500355036003650370037503800

Wavenumber (cm-1)

BEA

HL

LL

-Al2O3

Fig. 7. IR spectra of the samples, in the hydroxyl band range (3800 to 3450 cm1).

Table 2Catalyst acidity and platinum particle size.

Catalyst Si/AlFrama

Acidityb (lmol/gcat) Platinum particle average sizec

(nm)Brnsted Lewis

BEA 11 604 286 3.1HL 13 229

(579*)421(1052*)

2.9

LL 11 86(658*)

121(931*)

2.6

a Calculated from the mTOT band at 10801200 cm1 by using the correlationgiven in literature [33].

b Drawn from pyridine adsorption at 150 C followed by FT-IR.c Drawn from transmission electron microscopy.

* per gzeolite.

N. Batalha et al. /Microporous and Mesoporous Materials 166 (2013) 161166 1653.3. n-Hexadecane hydroisomerization

n-Hexadecane hydroisomerization was carried out on the threebifunctional catalysts at 220 C and 30 bar. In all cases, the n-hexa-decane molecules were transformed into isomers (M mono-branched isomers; B multibranched isomers) and crackingproducts. Moreover, all the catalysts were stable, since no deacti-vation was observed under the reaction conditions that were used.The absence of deactivation indicates the presence of a stronghydrogenating function, which avoids the transformation of theolefinic intermediates into coke. Consequently, the catalyst activityis directly connected to the density of the acid sites, since the acidsupport is similar on all catalysts [18]. Thus, as the composite sam-ples possess similar BEA zeolite acidity (around 600 lmol gzeo1),the catalysts activity should be proportional to the zeolite contenton the catalysts. Indeed, the LL catalyst (13 wt.% zeolite) was 3.1times less active than HL catalyst (40 wt.% zeolite) (Table 3). Thepure zeolite catalyst, however, did not follow the tendency andwas 50% less active than the HL catalyst (Table 3). The turnover fre-quency (TOF), i.e. the activity per acid site, of the composite cata-lysts was, as expected, similar (HL-83 h1; LL-72 h1) and high incomparison with the agglomerated BEA catalyst (22 h1). The rela-tive low activity and TOF of the BEA catalyst probably results fromthe BEA nanocrystallite (30 nm) aggregation into clusters (2.4 lm),which could provoke reactant diffusion limitations. Consequently,it is possible to conclude that even though the BEA catalyst is com-posed of nanocrystals, the crystallites aggregation phenomenonapproached the catalyst performance to that of a higher crystal sizeBEA zeolite.

Fig. 8 clearly shows a significant improvement in the isomersyield when using the composite catalysts. The maximum isomersyield improved from 35 to 80 wt.% when comparing the BEA zeo-lite with the LL catalyst. Meanwhile, the HL sample presented anintermediate behavior with a maximum isomers yield of 65 wt.%.Moreover, the M/B molar ratio was lower on the BEA catalyst thanon the LL catalyst, and slightly higher on the LL catalyst than on theHL catalyst (Fig. 9). These results indicate that, when the crystal-lites were isolated from each other as on the LL catalyst, the resi-dence time of the monobranched isomer inside the crystallitewas reduced, limiting their transformation and increasing the iso-mer yield. On the other hand, when the nanocrystallite wereagglomerated, as was the case on the BEA catalyst, the residencetime of the monobranched isomers was longer, which favoredthe formation of multibranched isomers and consequently crack-ing. Similar results were obtained by Win et al. for the benzoyla-tion of anisol [38], where BEA zeolite supported on silicon carbideexhibited high catalytic activity. Moreover, the composite catalystwas extremely stable in comparison with the BEA zeolite. Theauthors have justified the results by the improved product escap-ing rate, which reduced the secondary acid catalyzed condensationreactions, responsible for the carbonaceous species formation in-side the zeolite porosity.

Finally, the reduction of the zeolite agglomeration by perform-ing the direct germination of a BEA zeolite over an alumina surface,

Table 3Catalyst activity.

Catalyst Activity gn-C16 g1cat h

1 TOFa (h1)

BEA 3.0 22HL 4.4 85LL 1.4 72

a Turnover frequency activity per Brnsted acid site.

0

20

40

60

80

100

0 20 40 60 80 100

Isom

eriz

atio

n yi

eld

(wt.

%)

Conversion (%)

BEALLHL

Fig. 8. Isomerization yield as a function of n-hexadecane conversion.

0

0.5

1

1.5

0 20 40 60 80 100

M/B

Conversion (%)

BEALLHL

Fig. 9. Monobranched (M)/multibranched (B) ratio as a function of n-hexadecaneconversion.

166 N. Batalha et al. /Microporous and Mesoporous Materials 166 (2013) 161166not only enhanced the catalyst activity, but also enabled to obtain asubstantial increase in the isomerization selectivity, despite therather high acidity of the BEA zeolite.

4. Conclusion

The direct germination of BEA zeolite nanocrystallites on an a-Al2O3 surface prevented their agglomeration without significantlychanging the acidic and textural properties of the zeolite, as wellas the size of the metallic particles deposited. The composite cata-lysts were more active and more selective for isomerization thanthe BEA sample. These results were attributed to the BEA germina-tion of the zeolite on the a-Al2O3, which increased the ability of thereactant and products to diffuse in and out of the porous system ofthe zeolitic phase. By isolating the nanocrystals, the isomers resi-dence time inside the zeolite framework is reduced, thus avoidingsecondary reactions, including cracking and, consequently increas-ing the yield in monobranched isomers. In conclusion, the reduc-tion in the nanocrystal agglomeration enhanced the diffusionproperties of the BEA zeolite, resulting in high reaction activityand selectivity.

Acknowledgement

Nuno Batalha thanks Fundao para a Cincia e a Tecnologia(FCT) for the financial support (Ref. SFRH/BD/43551/2008).

References

[1] D.A. Bell, B.F. Towler, M. Fan, Coal Gasification and its Applications, first ed.,Elsevier, 2011.

[2] V. Calemma, C. Gambaro, W.O. Parker Jr., R. Carbone, R. Giardino, P. Scorletti,Catal. Today 149 (2010) 4046.

[3] C. Bouchy, G. Hastoy, E. Guillon, J.A. Martens, Oil Gas Sci. Technol. Rev. IFP 64(2009) 91112.

[4] A. Corma, Catal. Lett. 22 (1993) 3352.[5] H. Deldari, Appl. Catal. A 293 (2005) 110.[6] P.B. Weisz, Science 123 (1956) 887888.[7] P.B. Weisz, E.W. Swegler, Science 126 (1957) 3132.[8] F. Alvarez, F.R. Ribeiro, G. Perot, C. Thomazeau, M. Guisnet, J. Catal. 162 (1996)

179189.[9] M. Guisnet, F. Alvarez, G. Gianneto, G. Perot, Catal. Today 1 (1987) 415433.[10] F. Alvarez, G. Gianneto, M. Guisnet, G. Perot, Appl. Catal. 34 (1987) 353365.[11] G. Kinger, H. Vinek, Appl. Catal. A 218 (2001) 139149.[12] P. Raybaud, A. Patrigeon, H. Toulhoat, J. Catal. 197 (2001) 98112.[13] A. Lugstein, A. Jentys, H. Vinek, Appl. Catal. A 176 (1999) 119128.[14] J.K. Lee, H.K. Rhee, Korean J. Chem. Eng. 14 (1997) 451458.[15] M.C. Claude, J.A. Martens, J. Catal. 190 (2000) 3948.[16] W. Souverijns, J.A. Martens, G.F. Froment, P.A. Jacobs, J. Catal. 174 (1998) 177.[17] J.A. Martens, G. Vanbutsele, P.A. Jacobs, J. Denayer, R. Ocakoglu, G. Baron, J.A.

Muoz Arroyo, J. Thybaut, G.B. Marin, Catal. Today 65 (2001) 111116.[18] R. Merabti, L. Pinard, J.L. Lemberton, P. Magnoux, A. Barama, K. Moljord, React.

Kinet. Mech. Cat. 100 (2010) 19.[19] A. Soualah, J.L. Lemberton, L. Pinard, M. Chater, P. Magnoux, K. Moljord, Appl.

Catal. A 336 (2008) 2328.[20] C.H. Christensen, I. Schmidt, C.H. Christensen, Catal. Commun. 5 (2004) 543

546.[21] A. Corma, J. Catal. 216 (2003) 298312.[22] M.V. Landau, L. Vradman, V. Valtchev, J. Lezervant, E. Liubich, M. Talianker, Ind.

Eng. Chem. Res. 42 (2003) 27732782.[23] S.C. Larsen, J. Phys. Chem. C 111 (2007) 1846418474.[24] J. Prez-Ramrez, C.H. Christensen, K. Egeblad, C.H. Christensen, J.C. Groen

Chem, Soc. Rev. 37 (2008) 25302542.[25] M.V. Landau, D. Tavor, O. Regev, M.L. Kaliya, M. Herskowitz, V. Valtchev, S.

Mintova, Chem. Mater. 11 (1999) 20302037.[26] P.L. Lima, C.V. Gonalves, C.L. Cavalcante Jr., D. Cardoso, Micropor. Mesopor.

Mater. 116 (2008) 352357.[27] N. van der Puil, F.M. Dautzenberg, H. van Bekkum, J.C. Jasen, Micropor.

Mesopor. Mater. 27 (1999) 95106.[28] M.C. Lovallo, M. Tsapatsis, in: Advanced Catalysis and Nanostructured

Materials: Modern Synthesis Method, Academic Press, New York, 1996.[29] S. Brunauer, P.H. Emmett, E. Teller, J. Am. Chem. Soc. 60 (1938) 309319.[30] B.C. Lippens, J.H. de Boer, J. Catal. 4 (1965) 319323.[31] J.H. de Boer, B.C. Lippens, B.G. Lisen, B.C.P. Broekhoff, A. van den Heuvel, T.J.

Osinga, J. Interface Sci. 21 (1966) 405414.[32] J. Lynch, F. Raatz, P. Dufresne, Zeolites 7 (1987) 333340.[33] C. Coutanceau, J.M. Da Silva, M.F. Alvarez, F.R. Ribeiro, M. Guisnet, J. Chim.

Phys. 94 (1997) 765781.[34] D. Meloni, S. Laforge, D. Martin, M. Guisnet, E. Rombi, V. Solinas, Appl. Catal. A

215 (2001) 5566.[35] M. Maache, A. Janin, J.C. Lavalley, J.F. Joly, E. Benazzi, Zeolites 13 (1993) 419

426.[36] E. Loeffler, U. Lohse, C. Peuker, G. Oehlmann, L.M. Kustov, V.L. Zholobenko, V.B.

Kazansky, Zeolites 10 (1990) 266271.[37] A. Vimont, F. Thibault-Starzyk, J.C. Lavalley, J. Phys. Chem. B 104 (2000) 286

291.[38] G. Win, Z. El Benichi, C. Pan-Huu, J. Mol. Catal. A 278 (2007) 6471.

BEA zeolite nanocrystals dispersed over alumina for n-hexadecane hydroisomerization1 Introduction2 Experimental2.1 BEA coated alumina synthesis2.2 Physicochemical characterization2.3 Hydroisomerization reaction

3 Results and discussion3.1 Textural and morphological properties3.2 Acidic and metallic properties3.3 n-Hexadecane hydroisomerization

4 ConclusionAcknowledgementReferences