Novel Bio-Oil Hydrodeoxygenation Catalysts Based on Strong Electrostatic Adsorption

Fast pyrolysis of biomass produces an intermediate crude oil (‘bio-oil’) with potential to become fungible transportation fuel. Catalytic hydrodeoxygenation (HDO) has currently gained attention as a technique for bio-oil upgrading, due to its ability to convert highly oxygenated and reactive species to hydrocarbons. Most studies of HDO catalysts are process and not catalyst oriented; noble metal catalysts are typically used in conjunction with common supports, and important variables which affect catalyst performance are often not decoupled during preparation, including catalyst particle size, hydrothermal stability, and precision of bimetallic formations.

We hypothesize that a precisely synthesized combination of bimetallic base metal catalysts can possess requisite activity and selectivity for pyrolysis oil HDO. We studied the hydrotreatment of bio-oil from switchgrass (regular and catalytic fast pyrolysis) in a batch reactor, using a series of active and hydrothermally stable HDO catalysts. Strong electrostatic adsorption was used to prepare single and bimetallic combinations (Pt, Ru, PtRu, Ni, Cu, NiCu) on carbon, mesoporous alumina, and metal-doped SBA-15. Particle size was determined by XRD to fall within 3 – 5 nm with narrow distribution, and in many cases, as small as 1.0 nm. Catalyst stability was determined by examining the support crystal structure before and after reaction. The selectivities of each catalyst toward deoxygenation, hydrogenation, and coke inhibition were compared, and this information was used to identify optimum HDO catalysts.