Two stages catalytic pyrolysis of olive oil waste

Abstract

A study of the pyrolysis of a waste from the extraction of olive oil has been carried out. The work objective was to characterize the char, tar and gaseous phases generated in the process for their possible utilization in energy generation. On the other hand, the influence of a set of variables has been studied, including the efficacy of the dolomite as catalyst. Finally, as previous step to the design of industrial installations, a kinetic study of the process (catalyzed and uncatalyzed), based in the generation of the principal gases, has been carried out. In the uncatalyzed process only the influence of temperature (400–900 °C) was studied. In the catalytic process, the influence of temperature (500–800 °C) and mass of catalyst (0–100 g) was studied. Also, the dolomite effectiveness as catalyst was evaluated. For this motive, consecutive experiments, without reactivating dolomite, were carried out (0–6 runs), and the yields of solids, liquids and gases were determined. An increase in reaction temperature leads to a decrease in char and tar yield and to an increase in the gas phase yield. When the catalyst is present and when the mass of the same is increased, an important decrease in the tar yield and a high increase in the gas phase yield are produced. This increment in the yield of gases is very significant in the case of hydrogen. In addition, the catalyst is very stable. Your activity remains constant during six consecutive pyrolysis experiments, without need to carry out the reactivation of the same. In the kinetic study carried out, it has been considered that the gases are formed through parallel independent first-order reactions, with different activation energy. For uncatalyzed experiments, the experimental data, once adjusted to the model, provided activation energies of 77.8, 38.6, 70.5 and 16.9 kJ mol − 1 and the Arrhenius pre-exponential factors of 210.1, 9.9, 775.3 and 0.43 min − 1 for H 2, CO, CH 4, and CO 2, respectively. For catalyzed experiments (following the same sequence) the activation energies were 15.6, 16.5, 12.7 and 23.3 kJ mol − 1 and the Arrhenius pre-exponential factors 3.8, 1.4, 4.3 and 3.5 min − 1 .