02091nas a2200193 4500008004100000022001400041245010700055210006900162260000800231300001600239490000700255520138000262100002401642700002401666700003101690700002001721700002401741856013201765 2024 eng d a1463-926200aDepolymerization of waste polyethylene to linear alkenes via sequential dehydrogenation and metathesis0 aDepolymerization of waste polyethylene to linear alkenes via seq cOCT a10558-105660 v263 a

Polyethylene (PE) is the most abundantly sourced plastic and significant efforts are needed for its end-of-life management. The deconstruction of PE is an uphill task and requires the breaking of highly stable C-C bonds. Here we demonstrate that PE can be deconstructed to value-added dodecene, along with other long-chain alkenes. The PCP-iridium complex catalyzes the dehydrogenation of commercial and post-consumer polyethylene waste to produce dehydrogenated polyethylene (DHP) with 0.5-1.0% unsaturation. The DHP was subjected to an ethylene cross-metathesis reaction in the presence of suitable catalysts. Through meticulous optimization of reaction parameters, 63% selectivity toward dodecene, with 26% overall yield, was achieved. The practical significance of our method has been demonstrated by subjecting post-consumer plastic waste to dehydrogenation followed by ethylene metathesis to produce dodecene as a major product, together with long-chain alkenes. The PE deconstruction has been confirmed by recording molar mass before and after depolymerization using high-temperature gel permeation chromatography. The existence of dodecene has been unambiguously ascertained using GC, GC-MS, NMR, and IR spectroscopy. Thus, these results demonstrate the conversion of waste PE to value-added dodecene and long-chain alkenes under mild reaction conditions.

1 aKhopade, Kishor, V.1 aRajput, Nikhita, S.1 aRangappa, Raghavendrakumar1 aBarsu, Nagaraju1 aChikkali, Samir, H. uhttps://library.ncl.res.in/content/depolymerization-waste-polyethylene-linear-alkenes-sequential-dehydrogenation-and-metathesis02202nas a2200265 4500008004100000022001400041245011700055210006900172260000800241490000700249520127100256653001701527653003001544653002601574653002301600653002801623100002101651700001601672700003101688700002001719700001701739700002401756700002401780856013201804 2025 eng d a0947-653900aElectrochemical deconstruction of waste polyvinylidene chloride (PVDC) to value-added products in batch and flow0 aElectrochemical deconstruction of waste polyvinylidene chloride  cFEB0 v313 a

Chlorinated polymers have made enormous contributions to materials science and are commercially produced on a large scale. These chlorinated polymers could be recycled as chlorine sources to efficiently produce valuable chlorinated compounds owing to their facile release of HCl. Although the thermal stability of PVDC is low compared to PVC, this can be advantageous in terms of easy and fast dehydrochlorination. Herein, we report an efficient electrochemical chlorination using poly(vinylidene chloride) (PVDC) as a chlorine source that works in an undivided cell and applies to a good number of examples. This method works on commodity polymers such as waste PVDC-PVC pharma blister film, PVDC-PO multilayer food packaging, and compression molded sheets of Ixan PVDC (with heat stabilizer) with similar efficiency. Furthermore, this method also provides the dechlorination of PVDC up to 98 %, leading to unsaturated dechlorinated material. Converting PVDC into more stable unsaturated compounds, the release of harmful chlorine-containing gases during incineration can be minimized. Additionally, this method is not only restricted to batch processes but an electroflow process for PVDC dechlorination and electrosynthesis has also been demonstrated.

10achlorination10aElectrochemical recycling10aElectroflow-synthesis10aGraphitic material10aPolyvinylidene chloride1 aMishra, Subhadip1 aKar, Sourav1 aRangappa, Raghavendrakumar1 aPatil, Prashant1 aKadam, Vijay1 aChikkali, Samir, H.1 aSamanta, Ramesh, C. uhttps://library.ncl.res.in/content/electrochemical-deconstruction-waste-polyvinylidene-chloride-pvdc-value-added-products-batch02171nas a2200241 4500008004100000245011900041210006900160260000800229490000700237520131600244653001901560653002601579653001401605653001401619653001801633100002101651700002401672700002601696700003101722700002401753700002001777856013201797 2025 eng d00aRuthenium-catalyzed deconstruction of polyolefins: a strategy to up-cycle waste polyethylene to value-added alkene0 aRutheniumcatalyzed deconstruction of polyolefins a strategy to u cAPR0 v643 a

Synthesis of value-added products from post-consumer waste polyolefins is fascinating as well as challenging. Here we report ruthenium-catalyzed up-cycling of the polyethylene to long-chain alkene derivatives. The developed methodology mainly involves two steps i.e., dehydrogenation of polyethylene through hydrogen atom transfer and its metathesis using the HG-II catalyst. The dehydrogenation of polyethylene using ruthenium catalysis derived up to 3.38 %, of double bonds; with 90 % of the recovered polyolefin material. The obtained unsaturated polyethylene was subjected to cross-metathesis with ethylene using HG-II catalytic system. This resulted in the synthesis of predominantly dodecene (C12) derivatives, with 58 % selectivity, along with other derivatives of varying chain lengths. The overall reaction produced terminal and internal olefins in the ratio 1:0.8 respectively. The dehydrogenation of polyethylene and its deconstruction was confirmed by NMR spectroscopy, Gel Permeation Chromatography (GPC) and Differential Scanning Calorimetry (DSC). The origin of C12 selectivity has been demonstrated by control experiments. The scope of the methodology was extended to post-consumer waste polyethylene which gave high conversion to value-added dodecene derivatives as a major product.

10aDeconstruction10aHomogeneous catalysis10aruthenium10aUpcycling10aWaste plastic1 aPadhi, Ganeshdev1 aKhopade, Kishor, V.1 aMoyilla, Nageswararao1 aRangappa, Raghavendrakumar1 aChikkali, Samir, H.1 aBarsu, Nagaraju uhttps://library.ncl.res.in/content/ruthenium-catalyzed-deconstruction-polyolefins-strategy-cycle-waste-polyethylene-value-added