Research on the co catalytic pyrolysis of sludge and LDPE to produce aromatic hydrocarbons: providing a new path for the synergistic resource utilization of waste plastics and organic solid waste

Research Overview: According to the study published in Industrial Crops and Products, Volume 253, Part 3, November 2026, authors Kaisong Hu, Ting Luo, Yunpu Wang, and others proposed a technical route for co catalytic pyrolysis of sludge and low-density polyethylene (LDPE) to produce aromatic hydrocarbons. The catalyst used was a Ni/HZSM-5 composite catalyst (Ni) supported on biochar/ HZSM-5@biochar ）. This study focuses on the synergistic transformation of two typical solid wastes – municipal sludge and polyolefin waste plastics, which belong to the cross direction of waste resource utilization and chemical recycling of polymer materials.

Technical route and material background

LDPE is one of the main resin varieties for agricultural covering materials such as agricultural film and greenhouse film.

. Agricultural film often contains soil, moisture, and organic impurities after use, making it difficult to recycle. Traditional mechanical recycling has limited selectivity for mixed and aged materials. Catalytic pyrolysis can break down long chains of polyolefins and further aromatize them to obtain light aromatic hydrocarbons such as benzene, toluene, and xylene, which are basic chemical raw materials. This study mixed sludge with LDPE and utilized the organic and inorganic components in the sludge to participate in the reaction. At the same time, the hydrogenation/dehydrogenation activity of Ni component and the selective acidity of HZSM-5 molecular sieve were utilized to complete aromatization. The biochar carrier played a role in dispersing the active components and adsorbing them.

Association with the field of agricultural materials

From the perspective of agricultural materials, the value of this research mainly lies in the final treatment of agricultural film waste.

. Agricultural film and greenhouse film undergo long-term UV irradiation and thermal oxidative aging in the field, resulting in molecular chain breakage and carbonyl formation, making it difficult to directly reprocess after performance degradation. If it can be converted into aromatic hydrocarbons through catalytic pyrolysis during the recycling stage, it can provide a chemical recycling path for closed-loop recycling of agricultural films. At the same time, the commonly used light stabilizers, HALS (hindered amine light stabilizers), and antioxidants in agricultural film formulations delay the aging process and extend the service life of agricultural films; As a carrier for light stabilizers and antioxidants, weather resistant masterbatch determines the dispersion state and migration behavior of additives in the film. The more reasonable the design of the additive system, the longer the service life of the agricultural film, the more controllable the aging degree, and the relatively more stable the composition of the material flow entering the chemical recycling process.

Insights for the Polymer Additive Industry

This study suggests that agricultural film recycling should not only focus on mechanical regeneration, but also on the adaptability of chemical recycling routes to raw materials.

. For additive companies, this means two aspects of information: first, the formulation design ofweather resistant masterbatchandlight stabilizers,antioxidants,HALS, which not only meets the requirements of weather resistance, but also considers the impact on subsequent recycling processes; The second approach is the synergistic treatment of sludge and waste plastics, which provides a disposal possibility for agricultural films containing impurities that does not rely on high-purity sorting. It should be noted that this study is a laboratory scale catalytic pyrolysis research and has not yet involved engineering validation of actual recycled materials from agricultural films. Further work is needed to promote its conclusions to industrialization.

Research Information

• Journal: Industrial Crops and Products, Volume 253, Part 3
• Publication Date: November 2026
• Author: Kaisong Hu, Ting Luo, Yunpu Wang, Haiwei Jiang, Jiabo Wu, Yuhang Hu, Qi Wang, Jingsong Ke, Jiaheng Luo, Kewen Xu, Jiayi Xue, Wenguang Zhou, Liangliang Fan
• Catalyst: Ni/ HZSM-5@biochar
• Raw materials: sludge and LDPE
• Target products: aromatics

Information source:Co-upcycling of sludge and LDPE to aromatics via catalytic pyrolysis over Ni/ HZSM-5@biochar ， Organized by Herun Chemical.