Migration of Cl in the process for pyrolysis of corn straw and the influence of catalysis for dechlorination of bio-oil

Corn straw can be converted to bio-oil through pyrolysis. However, the application of bio-oil is severely restricted due to the high contents of oxygen and chlorine. The high level of oxygen in bio-oil reduces the heating value, and the chlorine makes bio-oil corrosive. In this work, the migration of Cl in the pyrolysis process was investigated, and eight catalysts were screened for dechlorination of bio-oil, with a lab-scale fixed-bed reactor. The results showed that with the increase of pyrolysis temperature, the amount of Cl that transferred into bio-oil was much less than that in gas or in char, and the amount of total-Cl in bio-oil increased monotonously with increasing temperature, indicating that a low temperature was preferable for obtaining a bio-oil with low content of Cl. Among the eight tested catalysts of δ-Al 2 O 3 , γ-Al 2 O 3 , acidified-α-Al 2 O 3 , acidified-γ-Al 2 O 3 , ZnO, MgO, SAPO-34, and ZSM-5, the two materials of MgO and ZnO were judged as the optimal catalysts for dechlorination. Graphical abstract