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Rapid Polyolefin Hydrogenolysis by a Single-Site Organo-Tantalum Catalyst on a Super-Acidic Support: Structure and Mechanism |
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| Authors: | Dr. Qingheng Lai Alexander H. Mason Amol Agarwal Wilson C. Edenfield Xinrui Zhang Dr. Takeshi Kobayashi Prof. Yosi Kratish Prof. Tobin J. Marks |
| Affiliation: | 1. Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL-60208-3113 USA Contribution: Conceptualization (equal), Data curation (equal), Formal analysis (equal), Investigation (lead), Methodology (lead), Writing - original draft (lead), Writing - review & editing (equal);2. Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL-60208-3113 USA Contribution: Data curation (equal), Formal analysis (equal), Writing - review & editing (equal);3. Department of Materials Science & Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL-60208-3113 USA Contribution: Data curation (equal), Formal analysis (equal), Writing - review & editing (equal);4. Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL-60208-3113 USA;5. Department of Materials Science & Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL-60208-3113 USA Contribution: Data curation (equal), Writing - review & editing (equal);6. U.S. DOE Ames National Laboratory, IOWA State University, Ames, IA50011-3020 USA |
| Abstract: | The novel electrophilic organo-tantalum catalyst AlS/TaNpx ( 1 ) (Np=neopentyl) is prepared by chemisorption of the alkylidene Np3Ta=CHtBu onto highly Brønsted acidic sulfated alumina (AlS). The proposed catalyst structure is supported by EXAFS, XANES, ICP, DRIFTS, elemental analysis, and SSNMR measurements and is in good agreement with DFT analysis. Catalyst 1 is highly effective for the hydrogenolysis of diverse linear and branched hydrocarbons, ranging from C2 to polyolefins. To the best of our knowledge, 1 exhibits one of the highest polyolefin hydrogenolysis activities (9,800 (CH2 units) ⋅ mol(Ta)−1 ⋅ h−1 at 200 °C/17 atm H2) reported to date in the peer-reviewed literature. Unlike the AlS/ZrNp2 analog, the Ta catalyst is more thermally stable and offers multiple potential C−C bond activation pathways. For hydrogenolysis, AlS/TaNpx is effective for a wide variety of pre- and post-consumer polyolefin plastics and is not significantly deactivated by standard polyolefin additives at typical industrial concentrations. |
| Keywords: | Chemical Recycling Hydrogenolysis Polyolefins Sulfated Alumina Tantalum |