Catalytic reforming of sewage sludge pyrolysis products over the self-derived char

The catalytic pyrolysis of sewage sludge (SS) over the self-derived char was performed in a lab-scale fixed-bed reactor. The effect of char and catalytic temperature on the product distribution and the evolution of organic nitrogen species (ONSs) in bio-oil were analyzed. Results showed that although the bio-oil yield with char reforming was comparable to the no catalyst case, much aliphatic and less ONSs content were found in the bio-oil, indicating that the bio-oil quality was improved with char reforming. The bio-oil and gas yields were almost constant at low reforming temperature (<500 degrees C), while the bio-oil yield reduced slightly and the gas yield increased at high reforming temperature (>500 degrees C). The highest aliphatic (19.78 %) and lowest ONSs (58.30 %) in the bio-oil could be obtained at the reforming temperature of 500 degrees C. Moreover, at 500 degrees C, the highest increment of H-2 and CO could be found, increased by 49.05 % and 25.36 %, respectively. The ash and demin-eralization char (D-char) as a catalyst was conducted to investigate the char reforming mechanism. It was found that the synergistic effect of inherent minerals and specific pore structures in char contributed to the recovery of high-quality bio-oil.

Automated summary

The catalytic pyrolysis of sewage sludge with self-derived char was investigated in this study. The results showed that char reforming improved the quality of bio-oil by increasing the aliphatic content and reducing the organic nitrogen species content. The temperature of reforming had an impact on the yields of bio-oil and gas, with the highest aliphatic content and lowest organic nitrogen species content obtained at 500 degrees C.