Catalytic pyrolysis of pine needles using metal functionalized spent adsorbent derived catalysts: Kinetics, thermodynamics and prediction modelling using artificial neural network (ANN) approach

Abstract

The current study was indented towards the evaluation of synergism of spent aluminum hydroxide nanoparticle (AHNP) adsorbent derived catalysts in the degradation of pine (Pinus roxburghii) needles through kinetics and thermodynamics analysis. Distinct kinetic (such as activation energy and pre-exponential factors) and thermodynamic (such as entropy, enthalpy, and Gibbs free energy) parameters were estimated through isoconversional (OFA and KAS) models. The study also aimed to envisage the reaction mechanism for all the distinct processes via Criado z master plots. Results illustrated the significant impact of all the different AHNP-derived catalysts in easing up the biomass degradation process. The KAS method evaluated the average activation energy for non-catalytic degradation as 130.01 kJ/mol, while the values changed to 120.95, 121.69, 125.99, 148.47 and 127.37 kJ/mol for Ni/AO, Fe/AO, Cu/AO, Zn/AO and Mo/AO catalyzed degradation, respectively. Amongst all, nickel (Ni/AO) and iron-doped (Fe/AO) catalysts brought the highest reduction in activation energy owing to the provision of strong acidic sites, high specific surface area, and better metal dispersion; subsequently leading to the increased rate of molecular scission and cracking reactions. Values of pre-exponential factor and thermodynamic parameter also displayed the positive impact of catalysts in terms of lowering down the molecular collisions, enthalpy, and disorderness of the system. Furthermore, artificial neural network (ANN) was also employed for the prediction of the biomass degradation where high regression (∼0.99) as well as low mean squared error (<10−5) illustrated the accurate prediction of complex biomass degradation by the ANN technique. Thus, the waste AHNP-derived catalysts have significant potential to be employed for the catalytic pyrolysis of pine needles together with aiding the cost-competitiveness, environmental sustainability, and renewability of the process.