(521e) Biochar Catalyst Screening for Enhancing Energy Recovery from Pyrolysis

Bio-oil and pyrolysis gas (py-gas) are two major energy products generated from pyrolysis. Bio-oil is typically corrosive and is a challenge to combust in standard equipment while py-gas is more readily usable for energy recovery. Therefore, biochar was assessed as a cost-efficient catalyst to reduce bio-oil production and increase py-gas production. Biochars derived from six industrial carbonaceous wastes were evaluated for the first time in terms of their catalytic abilities during pyrolysis. Paper mill sludge (p-sludge) biochar was the optimal catalyst based on its high py-gas production and py-gas energy, low catalyst loading, and long catalyst life. The p-sludge biochar catalyst approximately doubled py-gas yield compared to the control test. In addition, p-sludge biochar significantly decreased bio-oil yield (e.g. reduced by 40% at 800°C) and improved bio-oil quality by decomposing heavy hydrocarbons. The bio-oil catalyzed by p-sludge biochar contained fewer organic constituents based on GC-MS and GC-FID analyses. The catalytic activity of p-sludge biochar was stable and the majority of energy inherent to the products shifted from bio-oil to py-gas over four cycles of catalyst use. The p-sludge biochar had a high calcium content (39% dry weight basis of 800°C biochar) which likely played an important role in upgrading pyrolysis products.