DOI: 10.1002/cssc.201301242

Gasoline from Biomass through Refinery-FriendlyCarbohydrate-Based Bio-Oil Produced by KetalizationNuno Batalha,[a] Alessandra V. da Silva,[a] Matheus O. de Souza,[a] Bruna M. C. da Costa,[a]

Elisa S. Gomes,[a] Thiago C. Silva,[a] Thalita G. Barros,[a] Maria L. A. GonÅalves,[a]

Elina B. Caram¼o,[b] Luciana R. M. dos Santos,[c] Marlon B. B. Almeida,[c] Rodrigo O. M. A.de Souza,[a] Yiu L. Lam,[c] Nak�dia M. F. Carvalho,[d] Leandro S. M. Miranda,[a] andMarcelo M. Pereira*[a]

Introduction

Currently, renewable energy accounts for approximately 12 %of the world primary energy sources.[1] In contrast, less than0.1 % of the CO2 produced by anthropogenic means is recy-cled.[2] The inclusion of cleaner energetic matrices as well asa strict emission control can potentially minimize environmen-tal impact. However, it seems naive to believe that an environ-mental equilibrium will be reached without a severe change inthe consumption pattern and ways of production.

Biomass is the oldest source for energy generation, and theidea to produce chemicals and fuels from wood and fruits hadalready been proposed at the beginning of the last century.[3]

However, the feasibility to co-process the lignocellulose-de-rived compounds by using the refinery hardware that alreadyexists was proposed more recently.[4] Among several strategiesto introduce second-generation biomass into the refineries,[5]

pyrolysis or fast pyrolysis[6] has been generally accepted asa primary process to perform this transformation. Despite thesimple hardware and flexibility for loading different biomasssources, large quantities of several undesirable co-productssuch as char and polyaromatic compounds are formed rapidlyas a result of dehydrogenation and dehydration reactionsduring the thermoconversion process. Pyrolysis or fast pyroly-sis provides a dark-colored liquid, which contains highly oxy-genated compounds that are highly acidic, unstable, and im-miscible in hydrocarbons.[6a] To overcome these difficulties andimprove the bio-oil properties that hinder bio-oil introductioninto refinery, two main strategies have been proposed. In thehydrodeoxygenation process (HDO), bio-oil is treated usinga combination of hydrogenation/hydrotreatment at moderatetemperatures, for example, 200–300 8C, and moderate to highpressure, for example, 50–300 bar.[7] Alternatively, the catalyticpyrolysis oil (CPO) process is performed in the presence ofa catalyst at around 500 8C at atmospheric pressure.[4a, 8] Theformer uses large amounts of hydrogen to reduce the oxygencontent in the final bio-oil and decrease coke formation,[7, 9]

which results in an improvement of the bio-oil stability andmiscibility with hydrocarbons.[10] Following this strategy, severalchemical commodities were obtained by the catalytic upgrad-ing of hydrotreated bio-oil over conventional acid catalysts.[4c]

The introduction of biomass-derived compounds as an alterna-tive feed into the refinery structure that already exists can po-tentially converge energy uses with ecological sustainability.Herein, we present an approach to produce a bio-oil based oncarbohydrate-derived isopropylidene ketals obtained by reac-tion with acetone under acidic conditions directly fromsecond-generation biomass. The obtained bio-oil showeda greater chemical inertness and miscibility with gasoil than

typical bio-oil from fast pyrolysis. Catalytic upgrading of thebio-oil over zeolites (USY and Beta) yielded gasoline witha high octane number. Moreover, the co-processing of gasoiland bio-oil improved the gasoline yield and quality comparedto pure gasoil and also reduced the amount of oxygenatedcompounds and coke compared with pure bio-oil, which dem-onstrates a synergistic effect.

[a] Dr. N. Batalha, A. V. da Silva, M. O. d. . Souza, B. M. C. da Costa,E. S. Gomes, T. C. Silva, Dr. T. G. Barros, Dr. M. L. A. GonÅalves,Prof. R. O. M. A. d. . Souza, Prof. L. S. M. Miranda, Prof. M. M. PereiraInstituto de Qu�micaUniversidade Federal do Rio de JaneiroCentro de TecnologiaCidade Universit�riaRio de Janeiro 21949-909 RJ (Brazil)E-mail : maciel@iq.ufrj.br

[b] Prof. E. B. Caram¼oInstituto de Qu�micaUniversidade Federal de Rio Grande do SulAv. Bento GonÅalves 9500Porto Alegre, RS CEP 91501-970 and INCT EA (Energia Ambiente) (Brazil)

[c] L. R. M. d. . Santos, M. B. B. Almeida, Dr. Y. L. LamCentro de Pesquisas e Desenvolvimento Leopoldo A. Miguez deMello (Cenpes)Pesquisa e Desenvolvimento do Abastecimento, Tecnologia em FCCPetrobras, Ilha do Fund¼oAv. Hor�cio Macedo 950, Rio de Janeiro, 21941-598 RJ (Brazil)

[d] Prof. N. M. F. CarvalhoInstituto de Qu�micaUniversidade do Estado do Rio de JaneiroMaracan¼, Rio de Janeiro, 20550-013, RJ (Brazil)

Supporting Information for this article is available on the WWW underhttp://dx.doi.org/10.1002/cssc.201301242.

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By contrast, the CPO process avoids hydrogen consumptionand enhances the bio-oil quality for subsequent co-processingin the fluid catalytic cracking (FCC) unit, but a lower yield of or-ganic compounds is obtained compared to that from HDO.Moreover, further upgrading is often required to reduce theamount of oxygenated compounds.[8b] Despite the largeamount of work focused on bio-oil introduction into the refin-ery, it is clear that the thermoconversion of biomass introducesseveral drawbacks to the bio-oil properties and precludes itsuse in the refinery. Additionally, at high temperatures the sugarfraction (derived from cellulose and hemicellulose) of bio-oil isresponsible for charring and the formation of undesirable com-pounds.[7]

An alternative to the aforementioned processes is the acid-catalyzed hydrolysis of biomass,[11] which combined with se-quential reduction and organic transformation, for example,aldol condensation, is able to produce hydrocarbons in therange of gasoline and diesel.[12] Despite the originality of theseintegrated processes, most of them occur in the presence ofwater, which may hamper their implementation in a conven-tional oil refinery, and consequently, their application ona short/medium-term basis.

The acidic treatment of biomass produces carbohydrate-s,[11a, 13] which are poorly soluble in conventional gasoil feedsused in the refinery. However, carbohydrates with appropriatefunctionalization such as ketals can be envisioned as simplederivatives to overcome this problem[14] as this class of com-pounds is easily obtained,[15] stable under moderate thermalconditions, soluble in organic solvents, and can be reversed togive back the parent carbohydrate in the presence of waterand acids.[14] Moreover, ketalization has already been appliedto wood, with the aim to obtain glucose for further fermenta-tion.[16] These features make carbohydrate ketals eligible inter-mediates for the introduction of biomass into an oil refinerythrough a co-processing concept.

Herein, to address these questions, we present a new ap-proach for the conversion of carbohydrate into fuel by usinga regular refinery installation. We show clearly that througha biomass transformation, the carbohydrate was transformedlargely into fuels by a two-step process: bio-oil production byhydrolysis–ketalization reactions of biomass followed by cata-lytic upgrading (Figure 1). It is important to point out that thisapproach should be first applied to the biomass to promotecellulose and hemicellulose conversion into fuel and thenother complementary thermoconversion processes could beapplied to convert the biomass residue.[17]

Results and Discussion

From biomass to bio-oil

In carbohydrate chemistry, the synthesis of the respectiveketals is performed by the reaction of the desired carbohydratein the presence of both a carbonyl reagent and acid catalyst.In the case of isopropylidene ketals, the carbohydrate is react-ed with acetone and sulfuric acid.[14] This method was taken asa starting point to study the reaction conditions that enabled

us to obtain the desired ketals directly from sugarcane bag-asse.

However, it was observed immediately that the ketalizationconditions if used with sugarcane bagasse instead of a purecarbohydrate sample at room temperature were not adequateand no carbohydrate-derived isopropylidene ketals were ob-served. If the suspension of bagasse in acetone and sulfuricacid was heated to reflux, a dark-brown oil, rich in the desiredisopropylidene ketals, was produced. The effectiveness of thisone-pot process (biomass hydrolysis and carbohydrate ketaliza-tion) was measured by the weight difference between theoriginal bagasse and the solid residue recovered at the end ofthe reaction (bagasse conversion) as well as the amount ofbio-oil produced. The presence of the desired isopropylideneketals in the bio-oils was confirmed through the coinjection ofthe respective bio-oil with commercial or synthesized stand-ards of 1:2-5:6-di-O-isopropylidene-a-d-glucofuranose (DG),2,3:4,5-di-O-isopropilidene-b-d-fructopyranose (DF), and1,2:3,5-di-O-isopropilidene-b-d-xylofuranose (DX). Their frag-mentation patterns in the mass spectra were used to identifyother C5- and C6-derived carbohydrate ketals in GC–MS andGC � GC–TOF-MS chromatograms.

According to the biomass characterization presented inTable 1, the carbohydrate fraction represents 78.6 wt % of thetotal biomass composition, which represents the upper limitfor the biomass conversion in this work. The bagasse conver-sion, ratio of bio-oil/bagasse conversion [wt %/wt %], percent-age of acetone consumed in bio-oil formation, and the distri-bution per classes of compounds (estimated by GC–MS orGC � GC–TOF-MS, Tables S1–S6) for bio-oil obtained under dif-ferent experimental conditions are shown in Table 2.

The main compounds observed in the bio-oils are presentedin Table 3. In the GC–MS or GC � GC–TOF-MS analyses DX wasidentified as the major component of the bio-oils, except forBO4. DG was also identified as an important component. Otherisopropylidene ketals of pentoses (C5) and hexoses (C6) werealso observed in all of the bio-oils.

Figure 1. Steps to transform biomass into fuels. 1) Second-generation bio-mass treatment with acid and ketone to afford a bio-oil with unique charac-teristics (higher stability and miscibility in hydrocarbons), composed mainlyof ketal-type compounds, for instance, DG, DX, and DF. 2) Catalytic upgrad-ing of bio-oil and gasoil on a laboratory scale over conventional acid zeolitesto produce a high yield of gasoline with partial ketone recovery and a similaramount of coke compared to the cracking of pure gasoil.

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The results presented in Tables 2 and 3 show clearly that thereaction conditions have a profound impact on the primarycomposition of the bio-oil. The increase of the reaction tem-perature with a concomitant decrease in the amount of acidled to an increase in biomass conversion, as observed for BO5and BO6. In these oils, DX and DG were identified as the majorcomponents. Under these conditions, the acetone condensa-tion products were minimized, however, furan-derived prod-ucts were detected at 120 8C, which suggests a limiting tem-perature for the stability of the carbohydrates and/or ketals inthe presence of acids such as sulfuric acid.

Despite the semiquantitative nature of the analysis, it isbeyond any doubt that in all studied cases, high amounts ofproducts derived from the ketalization of the sugarcane bio-mass carbohydrates can be observed, which confirms theirone-pot extraction.

These results indicate that acetone has indeed protected thecarbohydrates from acid-catalyzed dehydration under the con-ditions employed for B01–B05 and, hence, improved both thechemical stability and bio-oil–gasoil miscibility (Figure S12)with minor amounts of furfural derivatives except for bio-oil

BO6. Notably, in addition to DX, DG, and DF, a huge diversityof isopropylidene ketal compounds as well as more complexproducts were observed (Figure S11).

The presence of ketals can also be inferred from the 1H NMRspectra of the bio-oils (Figure S1–S6). The formation of isopro-pylidene ketals as the major carbohydrate-derived product canbe observed from the signals at d= 3.5–4.5 ppm from H2–H6 ofthe carbohydrate ketal skeleton and at d= 5.8 ppm from H1

from the anomeric hydrogen atom of a-furanose ketals (xyloseand glucose). However, a large amount of acetone condensa-tion products, such as 2,6-dimethyl-2,5-heptadien-4-one (d=

6.2 ppm), were also observed for BO1, but not for BO2–BO6.13C NMR spectra corroborate the above analysis, in which sig-nals between d= 50–80 ppm correspond to the C2–C6 carbonatoms of the carbohydrate skeleton and the ketal carbonatoms are observed at d= 90–113 ppm.

The thermogravimetric (TG) analysis of sugarcane bagasseand the residual bagasse obtained after bio-oil preparation isshown in Figure 2 and the corresponding results in Table 4,which includes temperature ranges for biomass fractions (dif-ferential thermogravimetric (DTG) analysis results) and theweight loss for each fraction (extracted from TG results). Pris-tine biomass showed peaks ascribed to extractives, hemicellu-lose, cellulose, and lignin represented by the regions A, B, C,and D, respectively.[18] The DTG profile of residual bagasse dif-fers significantly from that of the pristine biomass. Firstly, therelative area of lignin (which shows a broad range of tempera-ture decomposition, centered around 430 8C) in the residualbagasses was higher than that observed in the sugarcane bag-asse, yet both BO5 and BO6 bagasse showed a higher ligninamount compared with BO1. These findings are in accordancewith the bio-oil yields presented in Table 2 and show clearlythat the ketalization process extracted the carbohydrate frac-tion of the biomass, which implies the high lignin amount inthe residual bagasse. If we consider that C5 isopropylideneketals are important components of the bio-oil, it is possiblethat highly modified cellulose is present in the residual bag-asse. For instance, the cellulose peak, which typically decom-

Table 1. Sugarcane bagasse composition.

Constituent Content [%]

humidity 10.2ash 0.9cellulose 40.0hemicellulose 33.4lignin 7.1fats 1.7protein 1.5carbohydrates 5.2carbon 43.9hydrogen 7.1nitrogen 0.3oxygen[a] 48.7

[a] Oxygen content determined by subtraction.

Table 2. Representative bio-oils obtained from sugarcane bagasse reaction with acetone under acidic conditions.

Bio-oil Experimental conditions Conversion Bio-oil/bagasse[a] Acetone Bio-oil composition[b] [wt %][%] [wt/wt] conv.[c] [%] C5

ketalsC6

ketalscondensedproducts[d]

furan others

BO1 heated to reflux (65 8C)in acetone/cyclohexane, H2SO4

37 (50)[e] 1.4 31 30 10 13 5 42

BO2 reaction under microwave irradiationin acetone, H2SO4

20 (27)[e] 1.5 33 39 43 7 2 8

BO3 reaction under microwave irradiationin acetone/cyclohexane, H2SO4

21 (28)[e] 1.5 33 39 48 4 3 6

BO4 aqueous hydrolysis in 0.1 m HCl followed byreaction in acetone heated to reflux

44 (59)[e] 0.4 n.d. 31 59 8 – 2

BO5 reaction at 90 8C and 4 barin acetone, H2SO4

54 (72)[e] 1.1 n.d. 53 25 4 1 17

BO6 reaction at 120 8C and 11 barin acetone, H2SO4

44 (59)[e] 1.1 n.d. 18 26 15 16 25

[a] Converted bagasse. [b] GC–MS and GC � GC–TOF-MS. [c] Estimated consumed acetone = {massoil�[massbagasse(initial)�massbagasse(final)]}massoil. [d] Ace-tone-condensed products. [e] Based on the total amount of carbohydrate present in the bagasse (Table 1).

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poses at around 360 8C in pristine biomass, appears as twopeaks in the residual BO5 and BO6 bagasses, a broad peak atthe same temperature and another one displaced to lowertemperatures (around 250 8C; peak C’ in Figure 2). However, re-sidual BO1 bagasse showed fractions that decomposed atlower temperatures, but it is not possible to relate these tem-peratures directly to the biomass composition. The BO1 bag-asse was largely affected by the reaction conditions, oncea greater amount of sulfuric acid was used. Notably, the residu-al bagasse did not suffer ketalization, which was judged fromthe solid-state 13C NMR spectrum of the residual bagasse (notshown).

To achieve success in the abovementioned reactions, somewater is necessary to induce the hydrolysis of the hemicellu-lose and cellulose present in the bagasse. However, the diiso-propylidene ketals formed are unstable in the presence of

both water and acidic media, which makes the amount ofwater present a key variable. In the cases presented in Table 2,solvents were used as received and the biomass was not driedbefore use. This is a possible explanation for the fact thatsome of the carbohydrates released from the bagasse under-went the reverse ketalization reaction and were not incorporat-ed into the bio-oil, particularly in the case of BO5 and BO6, inwhich the ratio of the weight of bio-oil to the weight of con-verted bagasse were lower than that of BO1–BO3.

In conclusion, the proof of concept of the direct synthesis ofcarbohydrate isopropylidene ketals from sugarcane biomasswas demonstrated unambiguously by semiquantitative chro-matographic and spectroscopic analysis of the one-pot (BO1,BO2, BO3, BO5, and BO6) and two-step (BO4) reaction of thebiomass with acetone. A detailed quantitative analysis of suchbio-oils is still necessary to determine the exact amounts of

Table 3. Main compounds observed in bio-oils.

Compound Formula Structure Bio-oil

1,2-O-isopropylidene-a-d-xylofuranose C8H14O5 BO1, BO2, BO3, B05, BO6

2,3:4,5-di-O-isopropylidene-b-d-fructopyranose C12H20O6 BO2, BO3, BO4

1,2:5,6-di-O-isopropylidene-a-d-glucofuranose C12H20O6 BO1, BO2, BO3, BO4, BO5, BO6

1,2:3,5-di-O-isopropylidene-a-d-xylofuranose C11H18O5 BO1, BO2, BO3, BO4, BO5, B06

1,2:3,5-di-O-isopropylidene-b-l-arabinopyranose C11H18O5 BO1, BO3, BO5, BO6

1,2-O-isopropylidene-d-glucofuranose C9H16O6 BO3

2,6-dimethyl-2,5-heptadien-4-one C8H14O1 BO1

1,1,3,6,8-pentamethyl-1,2-dihydronaphthalene C15H20 BO1

1,6-Anhydro-3,4-O-isopropylidene-2-O-methyl-b-d-galactopyranose C10H16O5 BO1, B05, BO6

2-methyl-2-nonen-4-one C10H18O1 BO1

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the C5- and C6-derived ketals and is in progress. Moreover, bio-mass conversion and the type of bio-oil are affected stronglyby different reaction conditions. Further additional work forthe optimization of several parameters, for instance, theamount of acid, type of acid, reaction conditions, and amountof water is required.

From bio-oil to fuels

The catalytic cracking of pristine bio-oil (BO1) and gasoil aswell as 20 % bio-oil (BO1)/gasoil mixture was performed overthree different zeolites, Beta, USY, and ZSM-5 (propertiesshown in Table 5). These zeolites were chosen based on theircommon use in refinery processes.[19] Both USY and Beta zeo-lites were effective in the conversion of the feeds, whereasZSM-5 was much less effective (Table S7).

As a result of the small scaleof the catalytic test, the amountof gas was not determined accu-rately; only the gas compositionwas analyzed. Yet from the de-termination of the amount ofliquid and coke, it is clear thata large amount of gas wasformed for all feeds. The prod-ucts were analyzed in terms ofthe yields of the fractions ob-tained typically from the crack-ing of gasoil—gasoline, lightcycle oil (LCO), heavy com-pounds, and coke—as well as interms of the classes of com-pounds (aromatics, oxygenates,paraffins, etc.) for each carbonnumber (detailed characteriza-tion is presented in Tables S8–S17).

The products both in terms of fractions and classes of com-pounds differed significantly for each zeolite tested. For allfeeds, neat gasoil, neat bio-oil, or a mixture, Beta zeolite gavethe largest diversity of products and a larger amount of polyar-omatic compounds (Figure S16, Tables S10 and S12). Converse-ly, USY enhanced the gasoline fraction. These differences in thecatalyst performances reveal the importance of the crystallinestructure and acidity of the zeolites, which reinforces that BO1was upgraded catalytically and that thermal degradations didnot occur significantly. Among the zeolites studied, USY showsthe most promising results with respect to fuel production.The results for product distribution as well as the type of com-pounds in gasoline and LCO that were obtained with this zeo-lite are presented in Figure 3 for BO1, BO2, and DG mixtureswith gasoil.

Firstly, experimental yields for each fraction in 20 % BO1/gasoil and 40 % BO1/gasoil model mixtures were compared toweighted values (in terms of wt %) of pristine BO1 and gasoil.These values are shown as horizontal bars in Figure 3 A. Thegasoline yield increased remarkably, whereas the yields of LCO,heavy compounds, and coke decreased. These results are clear

Figure 2. TG analysis of pristine sugarcane bagasse as well as residual bagasse after BO1, BO5, and BO6 produc-tion. DTG analysis is presented on the left, and the weight loss for the biomass fraction is shown on the right.

Table 4. Thermogravimetric (TG) analysis of sugarcane bagasse and resid-ual bagasse obtained after bio-oil preparation.

Sample Peak Tpeak

[8C]Weight loss[%]

Residue[%]

C’ 246 19.5BO6 C 361 10.1 22.1

D 453 44C’ 252 24.7

BO5 C 358 8.1 15.1D 427 48.7

C’’’ 149 11.7C’’ 185 6.7

BO1 C’ 241 3.8 32.5C 360 3.6D 422 34.7A 219 8.3

sugarcane bagasse B 308 40.3 13.2C 360 25.5D 427 7.7

Table 5. Properties of USY, ZSM-5, and Beta zeolites used in the catalyticupgrade tests.

Property ZeoliteUSY ZSM-5 Beta

Si/Al [SAR] 13 41 17BET surface area [m2 g�1] 605 410 740micropore volume [cm3 g�1] 0.24 0.12 0.30n-hexane activity [mmol gcat

�1 min�1][a] 2.45 2.20 1.80

[a] Catalyst activity in n-hexane cracking (compared at conversion�10 %for all catalysts). Catalytic test conditions: 500 8C, 1 bar, 11 % v/v of n-hexane in N2, flow of N2 30 mL min�1.

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evidence that gasoil improves the bio-oil conversion into gaso-line.

Secondly, the selectivities of different classes of compoundsin the gasoline and LCO fractions are presented in the piegraphs in Figure 3 B and 3 C. The gasoline fraction of BO1, pureor in a mixture with gasoil, is composed mainly of monoaro-matics (from 7–10 atoms), the amount of which increased withthe bio-oil proportion in the mixture, whereas the amount ofparaffins and naphthenes decreased. Pure BO1 showed a lowgasoline yield albeit with a high selectivity for aromatic com-pounds. The yields of the aromatic compounds as a functionof feed composition are compared in Figure 3 D, which showsthat the BO1/gasoil mixtures gave the highest yields in aromat-ics. Therefore, gasoline with a higher octane number was ob-served. In contrast to gasoline yield, a lower amount of theLCO fraction was obtained from the co-processing of 20 and40 % BO1/gasoil mixtures compared with the weighed amountof product from independent processing. The LCO obtained by

co-processing was composed of50 % diaromatics, which is similarto that obtained with puregasoil but much higher thanthat obtained with pure bio-oil.Notably, in these LCO fractions,paraffins and olefins decreasedcompared with that from pris-tine gasoil. This is similar to thatobserved in the gasoline frac-tion.

The selectivity of oxygenatedcompounds in gasoline was rela-tively high from pristine BO1(14.6 %). However, during BO1co-processing, except acetone,no oxygenated compounds weredetected. Likewise, the crackingof neat BO1 yielded a largeamount of oxygenated com-pounds in the LCO fraction witha yield of 9.7 wt % of the liquidfraction. The selectivity of oxy-genated compounds for themixtures 40 % BO1 and 20 %BO1 were 1.2 and 0.6 wt %, re-spectively. If we consider that nooxygenated compound shouldbe derived from the pristinegasoil, the weighted values ofthese oxygenates would be 3.9and 1.9 wt %, respectively (Ta-bles S11–S14). Hence, the co-processing resulted in threetimes less oxygenated species,which once again reveals thebenefits of the process. Briefly,co-processing led not only tohigher gasoline yields but also

to a product with improved quality and octane number.To demonstrate that the above results of the co-processing

of the ketalized bio-oil with gasoil is of a general nature, otherfeeds were co-processed with gasoil in 20/80 wt % mixtures.They included BO2 (which contained ketal compounds of C5

and C6 carbohydrates and a lower amount of ketone conden-sation products) and DG (used as a reference). A gasoline frac-tion slightly lower and an LCO fraction two to three timeshigher than those observed for pure gasoil as well as a largeramount of coke is shown in Figure 3 A. Once again, we ob-served that a large amount of monoaromatic compounds wasformed in the gasoline fraction during co-processing anda great decrease in oxygenates in both the gasoline and LCOfractions (Figure 3 B and 3 C). Furthermore, the acetone incor-porated as isopropylidene was partially recovered. For in-stance, the catalytic cracking of 20 %BO1 resulted in 4 wt %acetone in the gasoline fraction. Thus, if we consider that31 wt % of acetone is converted into products in BO1, we can

Figure 3. Catalytic cracking of pristine gasoil, pristine bio-oil, bio-oil/gasoil, and DG/gasoil over USY: A) fractionsand B) and C) class of compounds. The fractions obtained were gasoline (boiling point up to 216 8C), LCO (boilingpoint between 216 and 343 8C), and heavy oil (remaining liquid compounds). During co-processing, gasoline wasthe main fraction, and the amount of coke was similar to that of pristine gasoil. Experimental yields for the mix-tures were compared to weighted values from pristine BO1 and gasoil (these values, indicated by the horizontalbar, were calculated by weighting the results of individual feed, bio-oil, and gasoil in terms of the amount [wt %]of each of these feeds in the mixture). From this it can be observed that the yields of gasoline were higher andthat of LCO, heavy oil, and coke were lower than the weighted yields. Gasoline and LCO compositions are repre-sented according to the different compound classes (pie graphs). D) The co-processing of bio-oil and gasoil led tothe enrichment of the gasoline fraction in aromatic compounds and a slight decrease in paraffin and naphthenes.Aromatic species with seven, eight, and nine carbons atoms were observed. Such compounds in gasoline en-hanced the octane number from 86 in pristine gasoil to 91, 90, and 121, in BO1(20 %)+gasoil, BO1(40 %)+gasoil,and BO1, respectively. After the co-processing, oxygenated compounds were not observed in gasoline and weremainly distributed in the LCO fraction.

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estimate that an overall amount of 25 wt % of acetone was re-covered. In the other examples, the acetone recovery was ofthe same order of magnitude but lower. Therefore, the isopro-pylidene moiety of the compounds was incorporated into theproducts. This point will be further discussed in this manu-script.

The decrease of oxygenated compounds in the liquid phasewas accompanied by an increase of CO2 in the gas phase(Table 6). The amounts of CO2 produced from 20 % BO1/gasoilcracking over Beta, USY, and ZSM-5 zeolites increased by eight,two, and five times, respectively, from that expected from theamount of BO1 and gasoil. Besides CO and CO2, the gas prod-ucts contain hydrogen, a large amount of methane, and hydro-carbons from two to six carbons atoms (detailed gas composi-tions are presented in Tables S18–S20).

Finally, the regeneration profiles of spent USY in O2/He(Figure 4 and Table 7) showed that, regardless of the presenceof bio-oil, all coke was burnt in the typical temperature rangefor FCC catalyst regeneration. Moreover, the coke formed frombio-oil upgrading over USY was regenerated at a lower tem-perature than that from pristine gasoil. This indicates clearlythat the spent catalysts used for bio-oil upgrade can be regen-erated properly in a regular FCC unit.[20]

Insights for ketal compound transformation into aromaticsover USY

To gain a better understandingof the catalytic upgrading of bio-mass to fuels, one should obtaininformation of how the carbohy-drate skeleton and isopropyli-dene carbon atoms were incor-porated into the fuel. Hence 13Cisotopically labeled model com-pounds (99 % 13C), that is, DGwas used as the reactant.

The selectivities for the cata-lytic upgrading of DG with USYare presented in Table 8, and51.7 % conversion of DG was ob-served. Toluene, xylene, and tri-methylbenzene were the mainproducts, diaromatic compoundssuch as naphthalene wereformed in a minor amount.Hence, the formation of aromat-ics from this model compound isdemonstrated clearly.

Next, the 13C isotopic abun-dance for acetone, toluene,xylene, and naphthalene, ob-tained after the catalytic trans-formation of 13C-labeled DG atC-1 over Beta, USY, and ZSM-5zeolites is shown in Table 9. Allaromatic compounds showed

higher 13C isotopic abundance in comparison to the naturalisotopic distribution. In all cases, the abundance is above 0.3,which indicates a large contribution of the glucose ring to theformation of aromatics. Among the catalysts tested, USYshowed the highest increase in the amount of labeled carbonin toluene, xylene, and naphthalene of five-, 14-, and 15-fold,respectively, compared with that of the parent.

By contrast, no detectable difference in the isotopic distribu-tion for acetone (m/z = 58) was observed, which indicates that

Table 6. CO and CO2 yield in the BO1, gasoil, and BO1/gasoil catalyticcracking experiments over Beta, USY, and ZSM-5 zeolites. The amount ofeach product in 20 %BO1/gasoil is compared with their amount in pureBO1.[a]

Zeolite Feed Yield [wt/wt]CO CO2

Betagasoil 0.0 0.0

BO1(20 %) 0.3 (0.7) 8.1 (1.0)BO1 3.7 4.9

USYgasoil 0.0 0.0

BO1(20 %) 0.9 (1.0) 1.6 (0.7)BO1 5.0 3.7

ZSM-5gasoil 0.0 0.0

BO1(20 %) 0.0 (0.3) 1.7 (0.3)BO1 1.3 1.7

[a] Values inside parentheses represent the expected yields if the bio-oilCO and CO2 formation rate was the same if mixed with gasoil or pure.

Figure 4. Spent catalyst regeneration under an O2/He atmosphere. A) CO (m/z = 28) profile (USY); B) CO2 (m/z = 44) profile (USY); C) CO (m/z = 28) profile (BEA); D) CO2 (m/z = 44); E) Temperature range of CO and CO2 forma-tion and their relative proportions on the USY and Beta. CO and CO2 are released for pristine BO1 at lower tem-peratures than that on pristine gasoil, therefore, USY is regenerated easily after bio-oil upgrading. From the aboveresults some points can be emphasized, spent USY used in both pure and bio-oil/gasoil mixture can be regenerat-ed under regular conditions. The fact that both the CO and CO2 profiles for 20 %BO1 are intermediary to those ob-served on pristine bio-oil and gasoil suggests that the formed coke on the spent catalyst is originated from bothbio-oil and gasoil and reinforces the idea that this class of ketal compounds is more “stable” or “chemically inert”than that of bio-oil obtained by fast pyrolysis. Finally, E) shows a higher CO/CO2 ratio for pure BO1 or BO1/gasoilmixture than that of pure gasoil for USY, which is consistent with the higher amount of oxygen in the coke fromthe bio-oil cracking.

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carbon migration from glucose to isopropylidene to releaseacetone did not take place.

The catalytic upgrading of 13C-labeled DG at all six glucosecarbon atoms over USY is shown in Figure 5. The mass spec-trum of naphthalene was enriched remarkably in 13C comparedto that of the reference mass spectrum, which implies that thecarbon atoms present in naphthalene come mainly from theglucose skeleton. In the case of the mass spectrum of xylene,the incorporation of 13C was analyzed by investigation of the[M+�15] fragment (as a result of the loss of a methyl radical,CCH3). 13C atoms were more abundant than 12C atoms, buta more complex picture was presented, which indicates thatxylene was formed from the contribution of both isopropyli-dene and glucose carbon atoms. Trimethylbenzene showeda similar behavior (Figure S17). The case of acetone is present-ed in Figure S18.

Outlook

The conversion of carbohydrates into fuel by usinga regular refinery installation can largely mitigate CO2

emission. In practical terms, a significant amount ofgasoline and LCO from the co-processing comesfrom the bio-oil. A conservative estimation of theamount of bio-oil converted to gasoline is given inthe Supporting Information (materials and methods,green gasoline estimation). The amount of biomassin the bio-oil that is transformed into gasoline (ex-

cluding acetone) for 20 % BO1, 40 % BO1, and 20 % BO2 mix-tures with gasoil were 17.8, 27.2, and 19.7 wt %, respectively.

The biomass conversion into fuel by using regular refineryinstallation was achieved by a two-step process: bio-oil pro-duction by hydrolysis–ketalization reactions of biomass fol-lowed by catalytic upgrading.

From a more fundamental consideration, the initial testsusing mixtures of the new type of bio-oil and gasoil suggestedstrongly that a bimolecular reaction between the hydrocarbonsand bio-oil compounds takes place. The presence of hydrocar-bons enhances the deoxygenation of bio-oil and decreasescoke formation compared to pure bio-oil upgrading. The newbio-oil helps to improve gasoline yield and quality (to givea higher octane number) compared to the processing of puregasoil. Probably, hydrogen transfer reactions,[21] which largelydominate hydrocarbon chemistry, also take place between bio-oil and hydrocarbon compounds; another clear advantage ofthis co-process over CPO and HDO. Hydrocarbon chemistryover acid catalysts is governed by bimolecular reactions,[22] and

Table 7. Temperature ranges of the regeneration profiles of spent USY in O2/He andCO/CO2 ratios.

Feed USY BetaCO/CO2 Trange [8C] CO/CO2 Trange [8C]ratio CO[a] CO2

[a] ratio CO[a] CO2[a]

gasoil 1.2 459–750 417–759 1.4 427–727 392–737BO1(20 %) + gasoil 2.0 437–717 380–727 1.2 425–726 373–734BO1 2.0 408–655 361–660 1.7 412–712 371–725

[a] Initial and final temperature were determined at the moment that CO and CO2

emissions were at a maximum of 5 %.

Table 8. Products of the catalytic upgrade of the 13C-labeled DG atcarbon 1 over USY. Both the recovered ketone and the solvent used toextract the products were not considered.

Compound Selectivity [%]

toluene 19.4xylene 12.1furan 3.9furfural 0.2trimethylbenzene 8.71,4:3,6-dianhydro-a-d-glucopyranose 2.2naphthalene 2.5methylnaphthalene 1.7dimethylnaphthalene 1.01,2:5,6-di-O-isopropylidene-a-d-glucofuranose 48.3

Table 9. Isotopic ratio m/z of the products that result from the catalyticupgrade of the 13C-labeled DG at carbon 1 over zeolites.

Zeolite Productacetone(m/z=59, 58)

toluene(m/z=93, 92)

xylene(m/z=107, 106)

naphthalene(m/z=129, 130)

reference 0.04 0.08 0.04 0.13Beta 0.05 0.39 0.35 1.48USY 0.06 0.42 0.55 1.95ZSM-5 0.05 0.31 0.44 1.53

Figure 5. Catalytic upgrade of 13C-labeled DG at all glucose carbon atomsover USY. The distribution of naphthalene, xylene, and toluene as a functionof the number of labeled carbon atoms incorporated (mass spectrum, fullbars) and their natural isotopic distribution (mass spectrum, empty bars).High proportions of 13C were observed in both products, 82 % of naphtha-lene was composed of molecules with more than six 13C atoms, both xyleneand toluene also revealed a greater proportion of 13C than 12C.

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the existence of this interaction between ketal or other oxy-genated compounds present in bio-oil and hydrocarbons canaffect their chemistry and open enormous opportunities in thefield of heterogeneous catalysis. Similar to that observed in thedesign of oil refinery, in which the process and catalysts aretailor-made as a function of oil feed and desired products, theabove results reinforce that ketal compounds are promisingfor selective conversion into fuel in the refinery by a properchoice of catalyst and process.

Finally, the approach to transform biomass into a bio-oil byusing a combination of mild-temperature conditions in thepresence of chemical reactants can contribute to shorten ourlong path to obtain cleaner fuels and a sustainable energymatrix.

Conclusions

Second-generation biomass was transformed into a bio-oil richin carbohydrate isopropylidene ketals. The biomass conversionand the bio-oil composition were influenced greatly by the re-action conditions. The isopropylidene-derived compounds en-hance the chemical stability of the bio-oil and the miscibility ofbio-oil into gasoil. Therefore, mixtures of bio-oil and gasoil canbe readily used in refinery processes.

The co-processing of gasoil and bio-oils enhanced bio-oilconversion and yielded gasoline with a high octane number.The spent catalyst can be regenerated under the typical condi-tions of a fluid catalytic cracking process.

Finally, catalytic upgrading of 13C-labeled 1:2-5:6-di-O-isopro-pylidene-a-d-glucofuranose showed that a large amount ofcarbon derived from the glucose unit of 1:2-5:6-di-O-isopropy-lidene-a-d-glucofuranose was distributed in the aromatic prod-ucts. This result is a definitive proof of concept that the carbonatoms from the carbohydrate are indeed incorporated intogasoline.

Experimental Section

Detailed materials and methods, bio-oil preparation and characteri-zation, catalytic upgrading, and product analysis are described inthe Supporting Information.

Methods

1H (200 MHz) and 13C NMR (50 MHz) solution spectra were acquiredin CDCl3, [D6]acetone, or CD3OD by using a Bruker spectrometer.Chemical shifts are referenced to the solvent peaks. GC–MS analy-sis of bio-oils was conducted by using an Agilent 6890 gas chro-matograph equipped with a DB5 ms column. BO3 and BO3 werealso analyzed by GC � GC–TOF-MS by using an Agilent 6890 gaschromatograph equipped with SPB-1 and BPX50 capillary columns.Gasoline product distribution and acetone quantification weremeasured by GC with flame ionization detection (FID) by using anAgilent 6890 gas chromatograph equipped with a PONA column.LCO distribution was calculated by GC � GC–FID by using an Agi-lent 6890 gas chromatograph equipped with a DB5 ms column. Mi-croGC analysis was performed by using an Agilent 490 MicroGCwith three channels: MS5 A, PPU, and Al2O3/KCl columns. TG analy-

sis was performed by using a Netzsch STA449 Jupiter (bagasse) ora Netzsch T6209 F1 Iris instrument.

Bio-oil preparation

BO1 and BO3 were obtained from the reaction of sugarcane bag-asse (500 mg), acetone (4 mL), cyclohexane (6 mL), and sulfuricacid (0.4 mL) heated under reflux at 65 8C for 2 h or under micro-wave radiation at 100 W and 55 8C for 30 min. In the case of BO2,pure acetone (10 mL) was used as the solvent under microwave ir-radiation (30 min, 100 W, 55 8C). BO4 was obtained in a two-stepprocedure: bagasse was subjected to hydrolysis in aqueous HCl(0.1 m) with heating to reflux for 1 h followed by reaction of thehydrolysate (60 mg) with acetone (1.2 mL) and sulfuric acid (48 mL).BO5 was obtained at 90 8C from sugarcane bagasse (500 mg), ace-tone (10 mL), and sulfuric acid (0.04 mL) under microwave irradia-tion by using a silicon carbide vessel with a final pressure of 4 bar.BO6 was obtained at 120 8C under the same conditions used forBO5 with a final pressure of 11 bar. For all bio-oils, with the excep-tion of BO4, after the reaction, the residual bagasse was collectedby filtration, washed with acetone, and dried over silica gel. The or-ganic phase was neutralized with solid NaOH and NaHCO3 (pH 7),and the formed salts were removed by filtration. The organicphase was then dried over anhydrous Na2SO4, filtered, and the sol-vent removed. In the case of BO4, after the hydrolysis reaction, thebagasse was collected by filtration, neutralized with basic resin, thesolids removed again by filtration, the aqueous phase lyophilized,and the residue submitted to the acetalization step at RT accordingto the procedure for BO1. The reaction solvent was recovered bydistillation and analyzed by GC–MS, which showed the integrity ofacetone and cyclohexane under the reaction conditions.

In all cases the residual bagasse was characterized by TG analysisand the bio-oils by GC–MS or GC � GC–TOF-MS and 1H and13C NMR spectroscopy. The bio-oil miscibility and stability in typicalFCC gasoil were tested at different bio-oil concentrations: 40, 20,and 15 % (w/w) using BO1 and 15 % (w/w) using BO2 in a test tubeat RT at 200 rpm for 30 min. The gasoil/bio-oil mixtures were thenleft to stand and the test tube was photographed at differenttimes.

Catalytic upgrade

The labeled DG and gasoil/bio-oil mixtures were catalytically up-graded over USY, Beta, and ZSM-5 zeolites. The cracking of labeledDG was performed under a nitrogen flow of 60 mL min�1 over15 min, and the final reaction temperature was 480 8C. The nominalzeolite/DG proportions used were 80:40 mg. The reaction productswere condensed with liquid nitrogen, extracted with dichlorome-thane, and analyzed by GC–MS.

The catalytic cracking of gasoil, its mixture with BO1, BO2, and DGand pure BO1 was performed using a nominal zeolite/oil propor-tion of 2:1 g (values for each test are presented in the SupportingInformation). The reaction was performed under a nitrogen flow of60 mL min�1 over 15 min, and the final reaction temperature was525 8C. The products were condensed at �196 8C and warmed toRT. The liquid fraction was analyzed by GC � GC–FID and GC–FID.The coke amount was determined by thermogravimetry, and thegaseous products were analyzed by microGC. The regeneration ofthe spent catalysts was studied under CO2, O2, and He atmos-pheres.

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Spent catalyst regeneration

The coked catalysts that result from the catalytic cracking reactionsdescribed above were submitted to regeneration under O2 (5 %) ina He atmosphere. The catalyst regeneration took place in a quartzreactor under a gas flow of 60 mL min�1. In each case, 100 mg ofthe coked catalyst was used. The reaction temperature rangedfrom RT to 1000 8C at 10 8C min�1. The effluent gases were moni-tored by using an on-line Mass Spectrometer MKS model Microvi-sion Plus. m/z values of 2 (H2), 4 (He), 16 (O/CH4), 18 (H2O), 28 (CO),30 (C2H6), 32 (O2), and 44 (CO2) were followed during the regenera-tion. Only coked Beta and USY catalysts were tested.

Acknowledgements

To Petrobras for supporting this project under contracts(4600338530 and 4600250882). To Oliveira B.G. for helping in TGanalysis. To Salgueiro F. and Saimon J.G. for technical assistance.M.M.P, N.M.F.C, R.O.M.A.S, and L.S.M.M gratefully acknowledgeO. A. C. Antunes (in memoriam) for his ideas on science as wellas for his partnership and commitment to friends and students.

Keywords: biomass · carbohydrates · cracking · hydrolysis ·isotopic labeling

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Received: November 19, 2013

Revised: February 5, 2014

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FULL PAPERS

N. Batalha, A. V. da Silva, M. O. d. . Souza,B. M. C. da Costa, E. S. Gomes, T. C. Silva,T. G. Barros, M. L. A. GonÅalves,E. B. Caram¼o, L. R. M. d. . Santos,M. B. B. Almeida, R. O. M. A. d. . Souza,Y. L. Lam, N. M. F. Carvalho,L. S. M. Miranda, M. M. Pereira*

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Gasoline from Biomass throughRefinery-Friendly Carbohydrate-BasedBio-Oil Produced by Ketalization

Refinery refinement: The conversion ofbiomass into fuel by using a regular re-finery installation can largely mitigateCO2 emissions. This goal is achieved bya two-step process: biomass is trans-formed into a carbohydrate-based bio-oil produced by hydrolysis–ketalizationreactions, then a gasoline with a highoctane number is produced by catalyticupgrading.

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