Co-pyrolysis, where a mixture of two or more different biomasses are subjected to
pyrolysis, has gained attention over the years. Many studies have revealed that it leads to
bio-oil production with desirable properties like reduced moisture content and enhanced
caloric value. In the present study, blends of cedar wood (CW), algal biomass (AB), and
digested sludge (DS) were subjected to co-pyrolysis in presence and absence of the
catalyst ZSM-5. Differential Scanning Calorimetry (DSC) analysis was carried out for 18
different combinations of these biomasses to assess the total activation energy (Ea),
change in enthalpy (ΔH), and change in Gibb’s free energy (ΔG) for these blends. The
lowest value of Ea (87.28 kJ/mol) and ΔH (80.49 kJ/mol) were obtained for the 2:1 wt/wt
catalyst to 1:1:1 wt/wt biomass blend of CW: AB: DS with ΔG value of 207.62 kJ/mol.Statistical analysis of the DSC data resulted in significant response surface
models (RSM) for Ea and ΔH, but could not model ΔG well. Additionally, it has
demonstrated that the catalyst addition to blends reduced the energy requirement for
pyrolysis. Therefore, based on the RSM models for Ea and ΔH, 2:1 wt/wt blend of ZSM–
5 to biomass: 57.14 wt % DS, 4.29 wt % AB and 38.57 wt % CW was chosen as the
optimum combination (OC). The 2:1 wt/wt ZSM–5: biomass blend containing equal
weight fractions of three biomasses produced a bio-oil with the highest aromatic
hydrocarbon yield of 89.38 wt %. The aromatic hydrocarbon content of 83.12 wt % was
obtained in the bio-oil produced from pyrolysis of OC. Naphthalene, anthracene and their
methyl derivatives were the main aromatic hydrocarbons in the bio-oil.ASPEN PLUS simulation of the AB, DS and CW co-pyrolysis system confirmed the findings obtained with the DSC experiments indicating that co-pyrolysis can reduce energy requirement and allowed both mass and energy balance calculations for the process
