Comparison of Reduced and Sulfided CoMo/c-Al 2 O 3 Catalyst on Hydroprocessing of Pretreated Bio-Oil in a Continuous Packed-Bed Reactor Divya R. Parapati, Vamshi K. Guda, Venkata K. Penmetsa, Sathish K. Tanneru, Brian Mitchell, and Philip H. Steele Department of Sustainable Bioproducts, Mississippi State University, Mississippi State, MS 39762; psteele@cfr.msstate.edu (for correspondence) Published online 00 Month 2014 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ep.12072 Pretreated bio-oil was hydroprocessed with conventional sulfided CoMo/g-Al 2 O 3 catalyst in a continuous packed-bed reactor. Hydroprocessing experiments were performed at a temperature of 350 to 400  C, 1500 psig hydrogen pressure, using a hydrogen flow rate of 500 mL/min at a liquid hourly space velocity of 0.2 h 21 . The results from sulfided catalytic experiments were compared with our prior studies on hydro- processing pretreated bio-oil with reduced CoMo/g-Al 2 O 3 cat- alyst. sulfided CoMo/g-Al 2 O 3 catalyst demonstrated higher catalytic activity and resulted in increased hydrocarbon fraction yields. Moreover, the quality of the hydrocarbon fraction, as determined by the acid value, higher heating value, and water content analysis, also improved. Sulfided CoMo/g-Al 2 O 3 catalyst produced a hydrocarbon fraction having a higher heating value of 44.4 MJ/kg, acid value of 0.5 mg KOH/g oil, and a total water content of 0.1%. Use of sulfided catalyst for hydroprocessing pretreated bio-oil decreased the oxygen content from 47.8 wt % in the pre- treated bio-oil to nondetectable limits (0 wt %) in the hydrocarbon fraction. The hydrocarbon fraction was also analyzed by detailed hydrocarbon analysis and simulated distillation. V C 2014 American Institute of Chemical Engineers Environ Prog, 00: 000–000, 2014 Keywords: bio-oil, pretreatment, hydroprocessing, catalysts INTRODUCTION Biomass, due to its carbon value, abundance, and renew- ability, is an attractive resource for the production of fuels as well as value-added chemicals. Lignocellulosic biomass has negligible sulfur, nitrogen, and inorganic content and is also considered CO 2 neutral [1]. Fast pyrolysis of biomass is a thermochemical process performed at 400 to 500  C in the absence of oxygen, produces bio-oil (60–75 wt %), solid char (15–25 wt %), and noncondensable gases (10–20 wt %); product distribution depends on the type of feedstock and process conditions employed [2]. Bio-oil is a complex mix- ture containing numerous oxygenates in the form of a wide range of functional groups, including alcohols, aldehydes, ketones, ethers, esters, acids, and others. These numerous oxygenated compounds result in 45 to 50 wt % oxygen con- tent, water is the most abundant oxygenated compound as it typically ranges between 25 and 30 wt % [2]. Bio-oil is a viscous and highly acidic with a pH typically ranging between 2.5 and 3.0, liquid product with a low heat- ing value (17 MJ/kg). Moreover, the presence of reactive oxygenates make bio-oil thermodynamically unstable and, upon storage, causes phase separation due to polymerization reactions [2–4]. Despite its disadvantages, bio-oils have been tested as boiler fuel for stationary power and heat produc- tion, for chemical extraction, and also tested as engine fuels. However, the oxygenated bio-oils invariably caused engine damage regardless of the engine type tested [5]. Therefore, bio-oil, to be utilized as a transportation fuel, must be upgraded to a stable hydrocarbon liquid [2,6,7]. A number of upgrading methods have been proposed to improve the bio-oil quality, physical and chemical properties, and to produce high-quality fuels from bio-oils. All depend on oxygen removal in one way or another. The upgrading methods include catalytic hydroprocessing [7], esterification [8–10], olefination [11–13], catalytic pyrolysis [14,15], hydro- deoxygenation (HDO) [7,16,17], steam reforming [18,19], decarbonylation, and decarboxylation [20]. Hydrodeoxygena- tion (HDO) has been studied extensively for conversion of bio-oil to liquid hydrocarbons. Elliot et al. developed a two-step hydrotreating process for upgrading of pyrolysis oil which was characterized by a low temperature mild hydrotreating step, performed at a temperature of 270  C and 13.6 MPa pressure to avoid poly- merization of oxygen-containing compounds, catalyst coking, and reactor plugging. This hydrotreating step was then fol- lowed by a higher temperature hydrocracking performed at 400  C and 13.6 MPa pressure to remove oxygen in presence of sulfided (CoMo/g-Al 2 O 3 and NiMo/g-Al 2 O 3 ) catalysts. This process of low temperature hydrotreating followed by hydro- cracking is now widely used by many HDO practioners. Sul- fided CoMo/g-Al 2 O 3 and NiMo/g-Al 2 O 3 catalyst have been studied extensively for HDO, due to their successs in deoxy- genating and cracking of pyrolysis oils [7,21–26]. Pacific Northwest National Laboratory (PNNL) researchers initially performed tests on biomass liquefaction products rather than fast pyrolysis bio-oil and screened 22 catalysts to determine their performance. The PNNL researchers observed that the sulfided forms of the CoMo and NiMo V C 2014 American Institute of Chemical Engineers Environmental Progress & Sustainable Energy (Vol.00, No.00) DOI 10.1002/ep Month 2014 1