Effects of Reactor Configuration on the Yield of Solid Carbon from Pyrolysis of Low-Density Polyethylene

Abstract

The formation of solid carbons by LDPE pyrolysis has been studied in three different reactors: a batch feed reactor with slow heating (BFRSH), a batch feed reactor with fast heating (BFRFH), and a semicontinuous feed reactor with fast heating (SFRFH). The yield to solid carbons was low in the batch reactors with slow and fast heating (<3%) even when LDPE was copyrolyzed with polystyrene, lignin, and other additives. The yield increased to values between 15 and 52% when a semicontinuous feed reactor with fast heating was employed, which can be attributed to a longer residence time of primary pyrolysis products and higher extents of condensation reactions. Using a quartz reactor in the semicontinuous feed reaction system produced solid carbons with a homogeneous morphology of monodisperse spherules in high yields (15-43%) at temperatures of 750 and 850 °C. A Hastelloy reactor used in the same configuration produced higher yields of solid carbons (33-52%) because of wall catalysis, but the solid carbons obtained included metal alloy particles.

Hydrodechlorination activity of catalysts based on nitrogen-doped carbons from low-density polyethylene

“…Thus, a carbon black structure is formed by successive deposition. Comparison with the carbons obtained only from LDPE [30] indicates that the insertion of nitrogen atoms does not affect to the morphology. Fig.…”

“…The solid carbons obtained by pyrolysis of LDPE as the only starting material are virtually free from nitrogen [30], therefore, the presence of nitrogen in the solid carbons obtained during the co-pyrolysis with nitrogen precursors can be interpreted as the result of doping. Table 1 shows the nitrogen content as obtained from elemental analysis of selected samples.…”

“…This effect can be observed in the experiments carried out at different time elapsing between feeding pulses. As that time increases, a slower displacement of the gas pyrolysis products takes place, thus increasing the residence time and the corresponding carbon yield [30]. In these conditions, the condensation reactions allowing the incorporation of nitrogen in the carbon structure are also promoted.…”

Effect of structural ordering of the carbon support on the behavior of Pd catalysts in aqueous-phase hydrodechlorination

“…Homemade graphitized supports (CB2800 and CBPE2600) were prepared from a commercial carbon black (CB; Alfa Aesar, 100 % acetylene) and from a carbon blacklike material obtained from pyrolysis of low-density polyethylene (CBPE), as described elsewhere [19,20]. Both CB and CBPE supports were heat-treated at temperatures of 2800 and 2600 o C, respectively, during 30 min under He flow.…”

Cracking of Durene over HY and H Zeolites

“…The third step is the pyrolysis of hydrocarbon (e.g. low-density polyethylene) in a quartz semi continuous feed reactor with fast heating to obtain solid carbons [4,5]. In recent years, the thermal decomposition of hydrocarbon fuel in hypersonic aircrafts is also a research hotspot, because hydrocarbon fuel is required not only for the propulsive power but also as a coolant with high cooling capacity due to its endothermic pyrolysis reaction at high temperature [6][7][8].…”