Catalytic co-pyrolysis of food waste digestate and corn husk with CaO catalyst for upgrading bio-oil

Abstract

Catalytic co-pyrolysis behavior of food waste digestate (FD) and corn husk (CH) with CaO catalysts derived from calcining calcium hydroxide (CH–CaO) and calcium acetate monohydrate (CA-CaO) for upgrading bio-oil was studied. For co-pyrolysis process, the char yield decreased while the bio-oil and non-condensable gas yields increased with the CH/FD mass ratio increased. Compared to co-pyrolysis without catalysts, the relative contents of acids and esters in bio-oil decreased while the phenols increased in the case of catalytic co-pyrolysis. The relative contents of nitrogen-containing compounds (NCCs) increased with the presence of CaO catalysts. When the CH/FD mass ratio was 1/4, the relative content of nitrogen-containing components in bio-oil was 41.42% for co-pyrolysis without CaO catalysts, but increased to 45.10% and 52.03% with CH–CaO and CA-CaO catalysts, respectively. CaO catalysts also reduced the content of CO2 and increased the contents of H2, CO and CH4 in non-condensable gas. Compared to CH–CaO, CA-CaO exhibited better catalytic performance for upgrading bio-oil for the more developed porous structure and more basic sites. Furthermore, a reaction pathway and mechanism of main NCCs formation during co-pyrolysis of FD and CH with CaO catalysts was proposed.