Kinetics of the Water Gas Shift over a Cu-based Catalyst for Pyrolysis Vapor Upgrading
Ross Houstona, Nicole Labbéb and Nourredine Abdoulmouminea,b
aBiosystems Engineering and Soil Science Department, University of Tennessee, Knoxville, TN 37996
bCenter for Renewable Carbon, University of Tennessee, Knoxville, TN 37996
Abstract
Biomass pyrolysis vapors have limited applications due chiefly to its high oxygen content. While many approaches are explored to reduce oxygen content in these vapors, hydrodeoxygenation has emerged as the most effective method to minimize carbon loss by removing oxygen as water. The goal of this study is to investigate hydrogen production for deoxygenation via the water gas shift reaction using carbon monoxide (CO), one of the major non-condensable gases of pyrolysis and steam, a by-product of hydrodeoxygenation.
Prior to the catalytic experiments, the Cu-based catalyst was characterized by physisorption for surface area and pore volume and elemental composition. Water gas shift experiments were carried out over the size reduced catalyst (0.425-0.600 mm) on a bench-scale catalytic packed bed reactor (PBR) in a CO-lean environment (70 vol. % water, 20 vol. % He, and 10 vol. % CO). The experimental temperatures varied from 150°C to 400°C at 50°C interval and three different weight hourly space velocities (1221, 2036 and 6107 cm3/g-min). A full-factorial experiment with three replicates was developed, and the conversion of CO was analyzed using a gas chromatograph (GC) equipped with a thermal conductive detector (TCD).
The surface area and pore volume of the catalyst were 62.174 m2/g and 0.218 cm3/g, respectively and its elemental composition is as follows: 50% copper oxide, 25% zinc oxide, <25% aluminum oxide, and a balance of graphite. Preliminary results show that CO conversion increases with increasing temperature and catalyst weight to maximum CO conversion of 85-90 % at 300°C and 350°C.
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