Extended Data Fig. 9: Large-scale experiments achieved using a gradient porosity carbon felt reactor.

a, To expand the design and applicability of the graded-pore reactor, a reaction apparatus was constructed using commercially available carbon felt materials. b, Similar to the previously constructed 3D-printed reactor, three different porosity carbon felts were placed inside a quartz tube in the pyrolysis reaction zones, with porosities of 94.0%, 91.3%, and 66.4% in Zones 1, 2, and 3, respectively. In the lower part of Zone 1, 20 g of LDPE feedstock was wrapped in carbon felt. The reaction apparatus was connected to an inert carrier gas flow (200 sccm) and power input (80–100 V), with a programmable controller preset to a pulsed heating cycle of 110 ms heating and 990 ms cooling. The inert carrier gas introduced at the bottom of the reaction tube drives the LDPE feedstock through the pyrolysis reactor. After passing through the reactor, the pyrolysis products are collected by a condenser immersed in a dry ice-ethanol bath. Meanwhile, any portion of the liquid hydrocarbon products that remained inside the pyrolysis reactor (that is, did not exit with the carrier gas) were also collected. This process was repeated 10 times to convert a total of 200 g of feedstock.