Flash Vacuum Pyrolysis of Low Density Polyethylene in a Free-Fall Reactor

Abstract

Polyethylene (PE) is the principal component of postconsumer plastic wastes. It is important to develop chemical techniques to decompose PE with a view to recycling and production of compounds that are valuable as fuel or industrial raw materials. The most common reactors in polymer pyrolysis are fluidized-bed types. Free-fall reactors do not suffer the disadvantages of fluidized beds related to inert gas employment. This flash pyrolysis study has shown that low density polyethylene (LDPE) can be continuously degraded in a free-fall reactor under vacuum to give a product quality superior to other methods. The total conversion (i.e., the sum of liquid and gas yield) is 43% at 8758C when the feed is 150-75 mm LDPE particles. Over 99% of the gaseous product is C 1 to C 4 , the ethylene monomer exceeding 64%. The bulk of the liquid product is paraffinic;

Flash pyrolysis of Silopi asphaltite in a free-fall reactor under vacuum

“…However, there are other works containing different raw materials such as coal, polymer and biomass. Karaduman et al [20] reported for pyrolysis of LDPE that both the liquid and gas yield produced in the free-fall reactor increased with temperature raising from 750 to 875 8C. The liquid and gas yield produced at a temperature of 750 8C, particle sizes of 150-75 mm and feed rate of 2 g min À1 were found as 6 and 37 wt.%, respectively.…”

“…The temperature profile of the reactor was determined previously [20] and it was observed that the reactor is operated isothermally between 400 and 1000 mm sections.…”

“…Free-fall reactors operating under vacuum, have no disadvantages such as extra heating for inert gas feed and diluting of gaseous products, have the benefit of both sweeping fixed-bed reactor and fluidized-bed reactor. Flash pyrolysis of hydrocarbon materials as coal [14], biomass [15][16][17][18] and plastics wastes [19,20] can be carried out in free-fall reactors. Flash pyrolysis of low-density polyethylene (LDPE) in free-fall reactor under vacuum was worked by Karaduman et al [20] and reported that the free-fall reactors did not suffer the disadvantages of fluidized beds related to inert gas employment.…”

“…Flash pyrolysis of hydrocarbon materials as coal [14], biomass [15][16][17][18] and plastics wastes [19,20] can be carried out in free-fall reactors. Flash pyrolysis of low-density polyethylene (LDPE) in free-fall reactor under vacuum was worked by Karaduman et al [20] and reported that the free-fall reactors did not suffer the disadvantages of fluidized beds related to inert gas employment. In addition, it has been shown that LDPE can be continuously degraded in a free-fall reactor under vacuum to give a product quality superior to other methods.…”

Effects of hydrogen-donating solvents on the thermal degradation of HDPE

“…These methods include gasification [3], hydrogenation [4], thermal and catalytic cracking [5,6], as well as the use of plastic wastes as a coke substitute in the steel industry. Among these methods, thermal cracking has been studied extensively [7][8][9][10][11]. The thermal degradation of polyolefins produces a mixture of hydrocarbons that is formed by gas (C 1 -C 4 ), liquid (C 5 -C 18 ) and waxy (C 18 -C 70 ) fractions.…”