Catalysis Today 195 (2012) 106–113 Contents lists available at SciVerse ScienceDirect Catalysis Today j ourna l ho me p ag e: www.elsevier.com/lo cate/cattod Effect of operating conditions on the coke nature and HZSM-5 catalysts deactivation in the transformation of crude bio-oil into hydrocarbons María Ibá ˜ nez, Beatriz Valle, Javier Bilbao, Ana G. Gayubo, Pedro Casta ˜ no ∗ Chemical Engineering Department, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain a r t i c l e i n f o Article history: Received 13 January 2012 Received in revised form 28 March 2012 Accepted 2 April 2012 Available online 26 May 2012 Keywords: Crude bio-oil Methanol Coke Deactivation Zeolite MFI a b s t r a c t A study has been carried out on the effect of operating conditions (bio-oil/methanol ratio in the feed, tem- perature) on the deactivation of HZSM-5 catalysts used in the production of hydrocarbons by catalytic conversion of crude bio-oil continuously fed into a fluidized bed reactor. The bio-oil to be fed into the reactor has previously been subjected to an on-line thermal transformation in which the pyrolytic lignin derivatives have been re-polymerized. The coke deposited on the catalyst has been studied using differ- ent analytical techniques (FTIR spectroscopy, MS/FTIR-TPO, 13 C CP-MAS NMR spectroscopy). The results evidence a direct relationship between coke deposition and deactivation and the concentration of bio- oil oxygenates in the reaction medium. Consequently, bio-oil conversion should be promoted in order to mitigate coke deposition. This is achieved using a HZSM-5 zeolite catalyst with a reduced SiO 2 /Al 2 O 3 ratio and increasing reaction temperature and methanol/bio-oil ratio in the feed. The acidity of the HZSM-5 zeolite also has an influence on the nature of the coke, given that it contributes to increasing coke conden- sation towards polycondensed aromatic structures, although this has a minor effect on bio-oil conversion decrease with time on stream. The results obtained evidence the interest of the initiatives for co-feeding bio-oil with methanol to obtain hydrocarbons. © 2012 Elsevier B.V. All rights reserved. 1. Introduction In order to reduce petroleum dependency, lignocellulosic biomass is a promising renewable source of fuels, hydrocarbons for petrochemical synthesis and hydrogen [1–3]. The flash pyrolysis of biomass allows producing a yield of around 70 wt% of a liquid bio- oil by means of different technologies, which are in an advanced state of technological development and are being implemented on a large scale [4–6]. Bio-oil may be obtained in delocalized rural areas (where the biomass is produced) and transported to a refinery (biorefinery) for its large-scale valorisation using the catalytic processes of modern refineries. Yan and Le Van Mao [7] emphasize the importance of ensuring compatibility in the coupled catalytic transformation of oxygenates and petroleum derivates. The incorporation of bio-oil into refinery units involves the FCC unit [8,9] and studies have been carried out on the catalytic cracking of bio-oil representative oxy- genates, which have been cracked together with n-heptene or with gas oil under similar conditions to those in the FCC [10–13] unit. It should be noted that the cracking route and the deoxygenation of the bio-oil oxygenate components compete for the acid sites on ∗ Corresponding author. Tel.: +34 94 6018435; fax: +34 94 6013500. E-mail address: pedro.castano@ehu.es (P. Casta ˜ no). the surface of the zeolite crystals [11]. Furthermore, the presence of oxygenates, such as guaiacol or phenol, contributes to the for- mation of coke [12]. Part of this coke blocks the pores due to the diffusional limitations of the bulky oxygenated molecules that are adsorbed on the outer surface of the zeolite crystals [13]. Furthermore, Gayubo et al. [14,15] proved that the transfor- mation of bio-oil oxygenated components into hydrocarbons on HZSM-5 zeolite catalysts has great similarities with the transfor- mation of methanol (MeOH) or dimethyl ether (DME). Mentzel and Holm [16] have studied the joint transformation of oxygenates with methanol, confirming the interesting perspective for co-feeding bio-oil into the methanol to hydrocarbon reaction. Gayubo et al. [17] have also found the different role of the bio-oil components in the coke formation, identifying the aldehydes and fenols as the main precursors of this coke, whose deposition is also significant in the catalytic conversion of the bio-oil aqueous fraction [18]. The significant role of bio-oil oxygenated composition in the formation of coke on the HZSM-5 zeolite has been quantified by the effective H/C ratio [19], whose increase favours the formation of aromatics and olefins and attenuates coke formation. The valorisation of crude bio-oil (without prior separation of heavy oxygenated compounds) is essential for an efficient carbon yield in the bio-oil. Nevertheless, this valorization through catalytic processes is curtailed by the problems associated with bio-oil feed- ing, blockage of the catalytic bed and catalyst deactivation, which 0920-5861/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.cattod.2012.04.030