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 delta-Al2O3, gamma-Al2O3, acidified-alpha-Al2O3, acidified-gamma-Al2O3, ZnO, MgO, SAPO-34, and ZSM-5, the two materials of MgO and ZnO were judged as the optimal catalysts for dechlorination.

Automated summary

This study investigated the migration of chlorine in the pyrolysis process and identified two optimal catalysts for dechlorination of bio-oil. The results suggested that a low temperature is preferable for obtaining bio-oil with low chlorine content.