Biomass conversion to hydrocarbon fuels using the MixAlcoä process at a pilot-plant scale Sebastian Taco Vasquez*, John Dunkleman, Swades K. Chaudhuri, Austin Bond, Mark T. Holtzapple Texas A&M University, Department of Chemical Engineering, College Station, TX 77843, United States article info Article history: Received 3 September 2013 Received in revised form 8 January 2014 Accepted 9 January 2014 Available online 31 January 2014 Keywords: MixAlcoä Biofuel Jet fuel Fermentation Carboxylate platform abstract Texas A&M University has built a MixAlcoä pilot plant that converts biomass to hydro- carbons (i.e., jet fuel, gasoline) using the following steps: fermentation, descumming, dewatering, thermal ketonization, distillation, hydrogenation, and oligomerization. This study describes the pilot plant and reports results from an 11-month production campaign. The focus was to produce sufficient jet fuel to be tested by the U.S. military. Because the scale was relatively small, energy-saving features were not included in the pilot plant. Further, the equipment was operated in a manner to maximize productivity even if yields were low. During the production campaign, a total of 6.015 Mg of shredded paper and 120 kg of chicken manure (dry basis) were fermented to produce 126.5 m 3 of fermentation broth with an average concentration of 12.5 kg m 3 . A total of 1582 kg of carboxylate salts were converted to 587 L of raw ketones, which were distilled and hydrogenated to 470 L of mixed alcohols ranging from C3 to C12. These alcohols, plus 300 L of alcohols made by an industrial partner (Terrabon, Inc.) were shipped to an independent contractor (General Electric) and transformed to jet fuel (w100 L) and gasoline (w100 L) byproduct. Published by Elsevier Ltd. 1. Introduction High global demand for fuels and the depletion of fossil fuels have motivated research into renewable fuels. Lignocellulosic biomass is one of the most abundant and sustainable feedstocks that can be converted to liquid hydrocarbon fuels [1]. The carboxylate platform produces liquid hydrocarbons from carboxylate intermediates [2e5]. The MixAlcoä process is a version of the carboxylate platform that does not require sterilization to obtain fuels. Fig. 1 illustrates each step in the MixAlcoä process. First, during the fermentation, the biomass is converted to raw fermentation broth (RFB), an aqueous mixture of carboxylate salts (C2eC7), nutrients, microorganisms, and impurities. In the descumming step, RFB is treated with lime followed by CO 2 , which precipitates cal- cium carbonate and eliminates many of the impurities. The descummed RFB is concentrated by evaporation, and the carboxylate salts are crystallized. In a batch reactor [6], the salts are thermochemically transformed into raw ketones, which are distilled and then hydrogenated to mixed alcohols [7]. In a plug-flow reactor, the mixed alcohols are dehydrated and oligomerized using a zeolite catalyst. This paper presents results from pilot-scale production of hydrocarbons using the MixAlcoä process. The pilot plant operated from February to December 2010. The emphasis was to produce 100 L of jet fuel for military testing; yield and effi- ciency were secondary considerations. * Corresponding author. E-mail addresses: sebrisco@hotmail.com, sebrisco@gmail.com (S. Taco Vasquez). Available online at www.sciencedirect.com ScienceDirect http://www.elsevier.com/locate/biombioe biomass and bioenergy 62 (2014) 138 e148 0961-9534/$ e see front matter Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.biombioe.2014.01.005