Impact of layered and delaminated zeolites on catalytic fast pyrolysis of microalgae using fixed-bed reactor and PY-GC/MS

Abstract

The aim of this work is to exploit the pyrolysis characteristics of microalgae Botryococcus braunii (BB) with a medium pore framework zeolite (MCM-22) and its delaminated counterpart with a higher external surface area zeolite (ITQ-2) using pyrolysis-gas-chromatography-mass-spectrometry (Py-GC/MS) and a fixed-bed reactor. The study evaluates the effect of synthesized zeolites that possess different pore size, shape and acidity on promoting deoxygenation reactions and producing aromatic compounds during the pyrolysis of microalgae. Further, the role of the shape of zeolites (layered & delaminated) for carbohydrate, protein and lipid-derived compounds formation is discussed. The Py-GC/MS results showed that the aromatic compounds (area%) was significantly higher (35.17 %) for delaminated & (28.76 %) for layered zeolites than non-catalytic pyrolysis (17.85%) at the catalyst/biomass ratio of 10.1. The increase in catalyst/biomass ratio from 3 to 10 at 550 °C has increased the aromatics (90.66 % for ITQ-2 & 75.25 %) for MCM-22 zeolites. In addition, ITQ-2 zeolite produced 20.47% higher aromatics than MCM-22 zeolites which is attributed to the thinner delaminated structure of ITQ-2 that makes reactants more accessible to the catalytic site and accelerate the deoxygenation reactions.