Thermal Degradation of Polystyrene by Lewis Acids in Solution

Abstract

The degradation of polystyrene in various Lewis acids [aluminum chloride, ferric chloride, boron triflouride etherate, and tin(IV) chloride] at different temperatures (75-125°C) has been studied in this work. The evolution of the molecular weight distribution (MWD) has been modeled using continuous distribution kinetics with a stoichiometric kernel for random chain scission. The degradation rate was the highest in the presence of aluminum chloride. The reactions were also carried out at different aluminum chloride concentrations, and the degradation rate was proportional to the fourth power of the Lewis acid concentration. The activation energy of polystyrene degradation in the presence of aluminum chloride, determined from the temperature dependence of the degradation rate coefficient, was 7.7 kcal/mol.

Thermal degradation of polystyrene in the presence of hydrogen by catalyst in solution

“…A similar trend is also observed for catalyst loading and higher catalyst loading favors degradation. A similar observation was also noticed by Karmore and Madras [26] using Lewis acid as a catalyst. The best-fit equation corresponding to Fig.…”

“…An Arrhenius plot (Fig. 10) is made with correlation coefficient 0.928 to determine the frequency factor and the activation energy of PS degradation based on true thermal degradation rate constants and found to be 0.8065 h À1 and 11.753 kcal mol À1 , respectively, which are comparable with the reported values [23,26,29,30].…”

“…Zhu [25] observed that degradation of PS was enhanced by the use of concentrated solution of phosphoric acid, sulfuric acid and zeolite. Karmore and Madras carried out thermal degradation of PS by Lewis acid catalyst (e.g., aluminum chloride, AlCl 3 ; ferric chloride, FeCl 3 ; stannic chloride, SnCl 4 and boron tri fluoride, BF 3 ) using chlorobenzene solvent at 75e125 C [26] and p-toluene sulfonic acid at 150e170 C using o-dichlorobenzene solvent [27]. Madras et al [28,29] and Sterling et al [30] used mineral oil at 275e350 C to carry out PS thermolysis to a moderate conversion.…”

Tertiary recycling of waste polystyrene using magnesium impregnated catalysts into valuable products

“…Heterogeneous catalysts have the advantage of non-corrosive nature, easily separating from liquid products, low disposal problems with higher activity and selectivity resulting environmental friendly setup [5]. Various heterogeneous catalysts used for the degradation of PS are basic catalysts like CaO, ZnO, Cr 2 O 4 , Fe 2 O 3 , HgO, SnO, PbO, and MnO [6] and acid catalysts like zeolites, FCC, MCM-41, FeCl 3 , AlCl 3 , SnCl 4 [7,8].…”

“…The extensive use of acidic bulk catalysts like AlCl 3 and SnCl 4 and acidic mesoporous catalyst like ZSM-5, Al 2 O 3 and MCM-41 etc., and as well as acidic supported and/or modified catalysts [7,8,14,[18][19][20] in the field of PS degradation invited our attraction to investigate acidic catalysts supported over acidic supports. Currently, MgCl 2 is the most common type of precursor and/or supporting material for different reactions, which are reported to be extremely active [21], therefore, for the said purpose MgCl 2 was selected as precursor active center.…”