Ultrasonic Pretreatment of Cowpea Bean Pod with K3PO4: Effect on Bio-Oil Yield and Phenolic Compounds Content

Ultrasonic pretreatment of cowpea bean pod biomass with addition tripotassium phosphate (K3PO4) was used to induce the production bio-oil enriched in phenolic compounds. An ultrasound bath operating at 40 kHz, 154 W power, and constant biomass:K3PO4 ratio 5:1 (m/m) for pretreatments different durations: 0.5, 1.5, 3, 6, 8, 12 h. After pretreatment, pyrolyzed a fixed bed reactor 600 °C, under flow N2 5 mL min-1. The pyrolysis results indicated that use K3PO4 reduced yield, when compared non-catalytic pyrolysis, caused increased devolatilization, increasing gas yield reducing formation biochar. Gas chromatography mass spectrometry (GC-MS) analysis bio-oils led significant increases phenolics contents, as well alteration chemical profile these highest content 8.12% m/m obtained submitted 1.5 h ultrasonic 4.89% untreated biomass.