Catalytic pyrolysis and bio-products upgrading derived from Chlorella vulgaris over its biochar and activated biochar-supported Fe catalysts

Abstract

Catalytic and non-catalytic pyrolysis of Chlorella vulgaris microalgae was studied and the temperature, as the primary variable, was assessed to optimize the process. By changing the temperature from 450–850 °C, the highest performance of 58.51 % was achieved in terms of energy recovery (ER) at the optimal temperature of 650 °C. Although known as a useless pyrolysis by-product, the remaining biochar was used as catalyst support to further improve the process efficiency. For this purpose, iron in various concentrations of 2.5, 5.0, and 10.0 wt% was used to impregnate the pristine and KOH-activated biochar. Due to the unique chemical and morphological characteristics of activated carbon, the metallic active sites were loaded more successfully. All catalysts were precisely examined via FT-IR, XRD, FESEM, BET and ICP-OES. Moreover, elemental analysis, GC, GC–MS, and TGA methods were used to investigate the bio-products characterization. Accordingly, in catalytic experiments, the energy recovery factor of biochar based catalyst (CBC), and activated biochar based catalyst (CAC) was increased from 58.51 % (optimum ER in non-catalytic) to 64.46 % and 71.58 %, respectively.