Main content area

The pyrolysis of coffee paper cup waste samples using non-isothermal thermo-analytical techniques. The use of combined kinetic and statistical analysis in the interpretation of mechanistic features of the process

Janković, Bojan
Energy conversion and management 2014 v.85 pp. 33-49
activation energy, chemical bonding, chemical species, crosslinking, depolymerization, energy, liquids, models, nitrogen, paper, pyrolysis, statistical analysis, temperature, wastes
Pyrolysis process of coffee paper cup samples was investigated in a flow stream of nitrogen at different heating rates (10, 20, 30 and 40°Cmin⁻¹), using thermo-analytical techniques. It was found that second pyrolysis stage can be described by Šesták–Berggren (SB) autocatalytic model, with mechanism function f(α)=α⁰.⁰¹¹(1−α)¹.⁴⁵⁹. Based on analysis of SB kinetic exponents (designated by M and N), it was found that second pyrolysis stage is mainly controlled by chemical process, involving reactions with reaction-order (n) higher than unity. Applying specific statistical analysis, in order to obtain precise distribution of reactivity, the discrete (binomial) distribution has shown that there are two important areas of current distribution for corresponding energy outcomes, within the apparent activation energy as random variable. The first “concentration” area of energy outcomes corresponds to start of chain end depolymerization reaction forming levoglucosan at high enough temperature region, while second “concentration” area of energy outcomes includes occurrence of macro-radicals in liquid phase propagate with radical addition on unsaturated C–C bonds, with cross-linking and formation of small chemical species. It was found that further elevating of temperature (above 340°C), will leads to fact that rate of tar-forming reactions increases and formation of char decreases.