Study on products characteristics from catalytic fast pyrolysis of biomass based on the effects of modified biochars

Abstract Biochar was produced from peanut shells pyrolysis and then modified by HCl and MnCl2, and the effects of modified biochars on the pyrolysis products characteristics were investigated. The catalytic effect of the biochar prepared at 650 °C is more suitable, and the products under 650 °C have lower acid content and higher phenol content than that under other temperatures. It was found that the modification effect of low concentration of MnCl2 was not obvious, which manifested as a higher phenol content under the catalysis of the HCl modified biochar. Then, different concentrations of MnCl2 were adopted and the highest phenol yield was obtained at 1.5 mol/L, which was higher than that of direct pyrolysis, about 78.9%. Besides, its acid yield was also the lowest, and the reduction was about 37.5%. The phenol products were analyzed under different concentrations of MnCl2 modified biochar and the results showed that the selectivity of alkylated phenol substances was greatly improved. When MnCl2 is 0.8 mol/L, the CO2 content was lowest, while the H2 content was highest, the increment was up to about 92.8% compared with that of direct pyrolysis. Therefore, the co-modified biochar with HCl and MnCl2 can better promote lignin cracking and generate more phenols.