| Title |
Investigation into the Reaction Pathways and Catalyst Deactivation for Polyethylene Hydrogenolysis over Silica-Supported Cobalt Catalysts |
| ID_Doc |
24897 |
| Authors |
Borkar, SS; Helmer, R; Panicker, S; Shetty, M |
| Title |
Investigation into the Reaction Pathways and Catalyst Deactivation for Polyethylene Hydrogenolysis over Silica-Supported Cobalt Catalysts |
| Year |
2023 |
| Published |
Acs Sustainable Chemistry & Engineering, 11, 27 |
| DOI |
10.1021/acssuschemeng.3c02202 |
| Abstract |
Chemical repurposing has emerged as a promising routeto valorize"end-of-use" plastic waste and mitigate its releaseto the environment. In this work, we applied silica-supported cobalt(5 wt % Co/SiO2) catalysts to produce liquid-range hydrocarbons(C-5-C-30) in the batch phase at 200-300 & DEG;C, 20-40 bar H-2, and 2-36 h with highselectivity and investigated the reaction pathways, the influenceof catalyst phase on the product yields and selectivity, and the catalystdeactivation mechanisms. Reaction conditions were optimized for improvingliquid product yields at 275 & DEG;C, 30 bar H-2, and 8h reaction time, giving a 55% liquid product yield (C-mole basis),comprising 75% of nonsolid products, with gas yields limited to & SIM;19%.By tracking product evolution over time and with varying cobalt surfacedensity, we propose a multipathway mechanism, including a dominant,nonterminal C-C cleavage route on the polymer chain over thecatalyst, which drives the high liquid product selectivity. The catalystalso showed recyclability over four reactions with reduced activityand a shift in yield toward liquid products after the first reaction.It was effectively regenerated by calcination under air at 450 & DEG;C.We combined the reactivity data with powder X-ray diffraction (PXRD),thermogravimetric analysis coupled with mass spectrometry (TGA-MS),and catalyst surface areas via N-2 physisorption of variousfresh, spent, recycled, and regenerated catalysts to attribute thereduced activity and selectivity shift mainly to the presence of arecalcitrant polymer species embedded on the catalyst, comprising10.5-18.5 wt % of the spent catalyst, which obstructs accessto active sites and increases liquid selectivity and overshadows theinfluence of carbonaceous coke or catalyst phase reduction to Co.Moreover, we successfully applied the catalyst to various postconsumerpolyethylene (HDPE and LDPE) samples. These results move the fieldtoward more sustainable and economically viable catalysts for thechemical upcycling of waste plastics. Base metalcobalt-based catalysts sustainably convert wastepolyethylene plastic to liquid fuels. With high recyclability, thesecatalysts show promise toward the transition to a circular plasticeconomy. |
| Author Keywords |
Plastics upcycling; polyolefins; polyethylene; cobalt oxide; base metals; circular economy |
| Index Keywords |
Index Keywords |
| Document Type |
Other |
| Open Access |
Open Access |
| Source |
Science Citation Index Expanded (SCI-EXPANDED) |
| EID |
WOS:001018129900001 |
| WoS Category |
Chemistry, Multidisciplinary; Green & Sustainable Science & Technology; Engineering, Chemical |
| Research Area |
Chemistry; Science & Technology - Other Topics; Engineering |
| PDF |
https://doi.org/10.1021/acssuschemeng.3c02202
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