Impact of the Experimental Parameters on Catalytic Activity When Preparing Polymer Protected Bimetallic Nanoparticle Catalysts on Activated Carbon.

Autor: Paris CB; Cardiff Catalysis Institute (CCI), School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K., Howe AG; Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore, Blk E2, #05-01, 9 Engineering Drive 1, 119077 Singapore., Lewis RJ; Cardiff Catalysis Institute (CCI), School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K.; Max Planck Centre for Fundamental Heterogeneous Catalysis (FUNCAT), Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K., Hewes D; Cardiff Catalysis Institute (CCI), School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K.; Max Planck Centre for Fundamental Heterogeneous Catalysis (FUNCAT), Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K., Morgan DJ; Cardiff Catalysis Institute (CCI), School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K.; HarwellXPS-the EPSRC National Facility for Photoelectron Spectroscopy, Research Complex at Harwell (RCaH), Didcot, Oxon. OX11 0FA, U.K., He Q; Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore, Blk E2, #05-01, 9 Engineering Drive 1, 119077 Singapore., Edwards JK; Cardiff Catalysis Institute (CCI), School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K.
Jazyk: angličtina
Zdroj: ACS catalysis [ACS Catal] 2022 Apr 15; Vol. 12 (8), pp. 4440-4454. Date of Electronic Publication: 2022 Mar 30.
DOI: 10.1021/acscatal.1c05904
Abstrakt: Sol immobilization is used to produce bimetallic catalysts with higher activity to monometallic counterparts for a wide range of environmental and commercial catalytic transformations. Analysis of complementary surface characterization (XPS, Boehm's titration, and zeta potential measurements) was used to elucidate alterations in the surface functionality of two activated carbon supports during acid exposure. When considered in parallel to the experimentally determined electrostatic and conformational changes of the polymer surrounding the nanoparticles, an electrostatic model is proposed describing polymer protected nanoparticle deposition with several polymer-carbon support examples described. Consideration of the electrostatic interactions ensures full deposition of the polymer protected nanoparticles and at the same time influences the structure of the bimetallic nanoparticle immobilized on the support. The normalized activity of AuPd catalysts prepared with 133 ppm H 2 SO 4 has a much higher activity for the direct synthesis of hydrogen peroxide compared to catalysts prepared in the absence of acid. Detailed characterization by XPS indicates that the surface becomes enriched in Au in the Au-Pd samples prepared with acid, suggesting an improved dispersion of smaller bimetallic nanoparticles, rich in Au, that are known to be highly active for the direct synthesis reaction. Subsequent microscopy measurements confirmed this hypothesis, with the acid addition catalysts having a mean particle size ∼2 nm smaller than the zero acid counterparts. The addition of acid did not result in a morphology change, and random alloyed bimetallic AuPd nanoparticles were observed in catalysts prepared by sol immobilization in the presence and absence of acid. This work shows that the deposition of polymer protected AuPd nanoparticles onto activated carbon is heavily influenced by the acid addition step in the sol immobilization process. The physicochemical properties of both the polymer and the activated carbon support should be considered when designing a bimetallic nanoparticle catalyst by sol immobilization to ensure the optimum performance of the final catalyst.
Competing Interests: The authors declare no competing financial interest.
(© 2022 The Authors. Published by American Chemical Society.)
Databáze: MEDLINE
Externí odkaz: