A New Bioinspired Perchlorate Reduction Catalyst with Significantly Enhanced Stability via Rational Tuning of Rhenium Coordination Chemistry and Heterogeneous Reaction Pathway

Jinyong Liu; Mengwei Han; Dimao Wu; Xi Chen; Jong Kwon Choe; Charles J. Werth; Timothy J. Strathmann

doi:10.1021/acs.est.6b00886

A New Bioinspired Perchlorate Reduction Catalyst with Significantly Enhanced Stability via Rational Tuning of Rhenium Coordination Chemistry and Heterogeneous Reaction Pathway

Jinyong Liu^*
, Mengwei Han
, Dimao Wu
, Xi Chen
, Jong Kwon Choe
, Charles J. Werth
, Timothy J. Strathmann

^*Corresponding author for this work

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

27 Citations (Scopus)

20 Downloads (CityUHK Scholars)

Abstract

Rapid reduction of aqueous ClO₄^- to Cl^- by H₂ has been realized by a heterogeneous Re(hoz)₂-Pd/C catalyst integrating Re(O)(hoz)₂Cl complex (hoz = oxazolinyl-phenolato bidentate ligand) and Pd nanoparticles on carbon support, but ClO_x^- intermediates formed during reactions with concentrated ClO₄^- promote irreversible Re complex decomposition and catalyst deactivation. The original catalyst design mimics the microbial ClO₄^- reductase, which integrates Mo(MGD)₂ complex (MGD = molybdopterin guanine dinucleotide) for oxygen atom transfer (OAT). Perchlorate-reducing microorganisms employ a separate enzyme, chlorite dismutase, to prevent accumulation of the destructive ClO₂^- intermediate. The structural intricacy of MGD ligand and the two-enzyme mechanism for microbial ClO₄^- reduction inspired us to improve catalyst stability by rationally tuning Re ligand structure and adding a ClO_x^- scavenger. Two new Re complexes, Re(O)(htz)₂Cl and Re(O)(hoz)(htz)Cl (htz = thiazolinyl-phenolato bidentate ligand), significantly mitigate Re complex decomposition by slightly lowering the OAT activity when immobilized in Pd/C. Further stability enhancement is then obtained by switching the nanoparticles from Pd to Rh, which exhibits high reactivity with ClO_x^- intermediates and thus prevents their deactivating reaction with the Re complex. Compared to Re(hoz)₂-Pd/C, the new Re(hoz)(htz)-Rh/C catalyst exhibits similar ClO₄^- reduction activity but superior stability, evidenced by a decrease of Re leaching from 37% to 0.25% and stability of surface Re speciation following the treatment of a concentrated "challenge" solution containing 1000 ppm of ClO₄^-. This work demonstrates the pivotal roles of coordination chemistry control and tuning of individual catalyst components for achieving both high activity and stability in environmental catalyst applications. © 2016 American Chemical Society.

Original language	English
Pages (from-to)	5874-5881
Journal	Environmental Science and Technology
Volume	50
Issue number	11
DOIs	https://doi.org/10.1021/acs.est.6b00886
Publication status	Published - 7 Jun 2016
Externally published	Yes

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@article{906d2a1e04da4085a148622ca069119c,

title = "A New Bioinspired Perchlorate Reduction Catalyst with Significantly Enhanced Stability via Rational Tuning of Rhenium Coordination Chemistry and Heterogeneous Reaction Pathway",

abstract = "Rapid reduction of aqueous ClO4- to Cl- by H2 has been realized by a heterogeneous Re(hoz)2-Pd/C catalyst integrating Re(O)(hoz)2Cl complex (hoz = oxazolinyl-phenolato bidentate ligand) and Pd nanoparticles on carbon support, but ClOx- intermediates formed during reactions with concentrated ClO4- promote irreversible Re complex decomposition and catalyst deactivation. The original catalyst design mimics the microbial ClO4- reductase, which integrates Mo(MGD)2 complex (MGD = molybdopterin guanine dinucleotide) for oxygen atom transfer (OAT). Perchlorate-reducing microorganisms employ a separate enzyme, chlorite dismutase, to prevent accumulation of the destructive ClO2- intermediate. The structural intricacy of MGD ligand and the two-enzyme mechanism for microbial ClO4- reduction inspired us to improve catalyst stability by rationally tuning Re ligand structure and adding a ClOx- scavenger. Two new Re complexes, Re(O)(htz)2Cl and Re(O)(hoz)(htz)Cl (htz = thiazolinyl-phenolato bidentate ligand), significantly mitigate Re complex decomposition by slightly lowering the OAT activity when immobilized in Pd/C. Further stability enhancement is then obtained by switching the nanoparticles from Pd to Rh, which exhibits high reactivity with ClOx- intermediates and thus prevents their deactivating reaction with the Re complex. Compared to Re(hoz)2-Pd/C, the new Re(hoz)(htz)-Rh/C catalyst exhibits similar ClO4- reduction activity but superior stability, evidenced by a decrease of Re leaching from 37\% to 0.25\% and stability of surface Re speciation following the treatment of a concentrated {"}challenge{"} solution containing 1000 ppm of ClO4-. This work demonstrates the pivotal roles of coordination chemistry control and tuning of individual catalyst components for achieving both high activity and stability in environmental catalyst applications. {\textcopyright} 2016 American Chemical Society.",

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A New Bioinspired Perchlorate Reduction Catalyst with Significantly Enhanced Stability via Rational Tuning of Rhenium Coordination Chemistry and Heterogeneous Reaction Pathway. / Liu, Jinyong; Han, Mengwei; Wu, Dimao et al.
In: Environmental Science and Technology, Vol. 50, No. 11, 07.06.2016, p. 5874-5881.

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

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T1 - A New Bioinspired Perchlorate Reduction Catalyst with Significantly Enhanced Stability via Rational Tuning of Rhenium Coordination Chemistry and Heterogeneous Reaction Pathway

AU - Liu, Jinyong

AU - Han, Mengwei

AU - Wu, Dimao

AU - Chen, Xi

AU - Choe, Jong Kwon

AU - Werth, Charles J.

AU - Strathmann, Timothy J.

N1 - Publication details (e.g. title, author(s), publication statuses and dates) are captured on an “AS IS” and “AS AVAILABLE” basis at the time of record harvesting from the data source. Suggestions for further amendments or supplementary information can be sent to [email protected].

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N2 - Rapid reduction of aqueous ClO4- to Cl- by H2 has been realized by a heterogeneous Re(hoz)2-Pd/C catalyst integrating Re(O)(hoz)2Cl complex (hoz = oxazolinyl-phenolato bidentate ligand) and Pd nanoparticles on carbon support, but ClOx- intermediates formed during reactions with concentrated ClO4- promote irreversible Re complex decomposition and catalyst deactivation. The original catalyst design mimics the microbial ClO4- reductase, which integrates Mo(MGD)2 complex (MGD = molybdopterin guanine dinucleotide) for oxygen atom transfer (OAT). Perchlorate-reducing microorganisms employ a separate enzyme, chlorite dismutase, to prevent accumulation of the destructive ClO2- intermediate. The structural intricacy of MGD ligand and the two-enzyme mechanism for microbial ClO4- reduction inspired us to improve catalyst stability by rationally tuning Re ligand structure and adding a ClOx- scavenger. Two new Re complexes, Re(O)(htz)2Cl and Re(O)(hoz)(htz)Cl (htz = thiazolinyl-phenolato bidentate ligand), significantly mitigate Re complex decomposition by slightly lowering the OAT activity when immobilized in Pd/C. Further stability enhancement is then obtained by switching the nanoparticles from Pd to Rh, which exhibits high reactivity with ClOx- intermediates and thus prevents their deactivating reaction with the Re complex. Compared to Re(hoz)2-Pd/C, the new Re(hoz)(htz)-Rh/C catalyst exhibits similar ClO4- reduction activity but superior stability, evidenced by a decrease of Re leaching from 37% to 0.25% and stability of surface Re speciation following the treatment of a concentrated "challenge" solution containing 1000 ppm of ClO4-. This work demonstrates the pivotal roles of coordination chemistry control and tuning of individual catalyst components for achieving both high activity and stability in environmental catalyst applications. © 2016 American Chemical Society.

AB - Rapid reduction of aqueous ClO4- to Cl- by H2 has been realized by a heterogeneous Re(hoz)2-Pd/C catalyst integrating Re(O)(hoz)2Cl complex (hoz = oxazolinyl-phenolato bidentate ligand) and Pd nanoparticles on carbon support, but ClOx- intermediates formed during reactions with concentrated ClO4- promote irreversible Re complex decomposition and catalyst deactivation. The original catalyst design mimics the microbial ClO4- reductase, which integrates Mo(MGD)2 complex (MGD = molybdopterin guanine dinucleotide) for oxygen atom transfer (OAT). Perchlorate-reducing microorganisms employ a separate enzyme, chlorite dismutase, to prevent accumulation of the destructive ClO2- intermediate. The structural intricacy of MGD ligand and the two-enzyme mechanism for microbial ClO4- reduction inspired us to improve catalyst stability by rationally tuning Re ligand structure and adding a ClOx- scavenger. Two new Re complexes, Re(O)(htz)2Cl and Re(O)(hoz)(htz)Cl (htz = thiazolinyl-phenolato bidentate ligand), significantly mitigate Re complex decomposition by slightly lowering the OAT activity when immobilized in Pd/C. Further stability enhancement is then obtained by switching the nanoparticles from Pd to Rh, which exhibits high reactivity with ClOx- intermediates and thus prevents their deactivating reaction with the Re complex. Compared to Re(hoz)2-Pd/C, the new Re(hoz)(htz)-Rh/C catalyst exhibits similar ClO4- reduction activity but superior stability, evidenced by a decrease of Re leaching from 37% to 0.25% and stability of surface Re speciation following the treatment of a concentrated "challenge" solution containing 1000 ppm of ClO4-. This work demonstrates the pivotal roles of coordination chemistry control and tuning of individual catalyst components for achieving both high activity and stability in environmental catalyst applications. © 2016 American Chemical Society.

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JO - Environmental Science and Technology

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ER -

A New Bioinspired Perchlorate Reduction Catalyst with Significantly Enhanced Stability via Rational Tuning of Rhenium Coordination Chemistry and Heterogeneous Reaction Pathway

Abstract

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