Search

Herein, the pyrolysis of low-density polyethylene (LDPE) scrap in the presence of a H-ZSM-11 zeolite was conducted as an effort to valorize plastic waste to fuel-range chemicals. The LDPE-derived pyrolytic gas was composed of low-molecular-weight aliphatic hydrocarbons (e.g., methane, ethane, propane, ethylene, and propylene) and hydrogen. An increase in pyrolysis temperature led to increasing the gaseous hydrocarbon yields for the pyrolysis of LDPE. Using the H-ZSM-11 catalyst in the pyrolysis of LDPE greatly enhanced the content of propylene in the pyrolytic gas because of promoted dehydrogenation of propane formed during the pyrolysis. Apart from the light aliphatic hydrocarbons, jet fuel-, diesel-, and motor oil-range hydrocarbons were found in the pyrolytic liquid for the non-catalytic and catalytic pyrolysis. The change in pyrolysis temperature for the catalytic pyrolysis affected the hydrocarbon compositions of the pyrolytic liquid more materially than for the non-catalytic pyrolysis. This study experimentally showed that H-ZSM-11 can be effective at producing fuel-range hydrocarbons from LDPE waste through pyrolysis. The results would contribute to the development of waste valorization process via plastic upcycling.

Lignin directly derived from lignocellulosic biomass has been named a promising source of platform chemicals for the production of bio-based polymers. This review discusses potentially relevant routes to produce renewable aromatic aldehydes (e.g., syringaldehyde and vanillin) from lignin feedstocks (pre-isolated lignin or lignocellulose) that are used to synthesize a range of bio-based polymers. To do this, the processes to make aromatic aldehydes from lignin with their highest available yields are first presented. After that, the routes from such aldehydes to different polymers are explored. Challenges and perspectives of the production the lignin-derived renewable chemicals and polymers are also highlighted.

In this work, we used pyrolysis to treat teabag waste (TBW). Changes in the pyrolysis temperature affected the composition and yield of the products. For example, more non-condensable gases and less char were produced with an increase in the pyrolysis temperature. Pyrolysis conducted under a nitrogen environment yielded caprolactam at temperatures between 400 and 700 &deg, C. An increase in the pyrolysis temperature from 400 to 500 &deg, C increased the caprolactam yield from 3.1 to 6.2 wt.%. At 700 &deg, C, the yield decreased to 4.6 wt.%. The highest caprolactam yield (i.e., 6.2 wt.% at 500 &deg, C) was equivalent to 59.2 wt.% on the basis of the weight of the non-biomass part of the TBW. The pyrolytic products other than caprolactam (e.g., combustible gases, pyrolytic liquid, and char) can function as fuels to supply energy during pyrolysis in order to increase and maintain the temperature. The higher heating values (HHVs) of the combustible gases and pyrolytic liquid produced at 500 &deg, C were 7.7 and 8.3 MJ kg&minus, 1, respectively. The HHV of the char produced at 500 &deg, C was 23 MJ kg&minus, 1, which is comparable to the HHV of coal. This work will help to develop effective pyrolysis processes to valorize everyday waste by recovering value-added chemicals such as polymer monomers and by producing alternative fuels.