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Title: Aqueous phase hydrogenation of phenol catalyzed by Pd and PdAg on ZrO 2

The impact of particle size of ZrO 2-supported Pd and of alloying with Ag was explored for hydrogenation of phenol in aqueous phase. Kinetic assessments were performed in a batch reactor, on monometallic Pd/ZrO 2 samples with different Pd loadings (0.5%, 1% and 2%), as well as on a 1% PdAg/ZrO 2 sample. The catalytic activity normalized to accessible Pd (turnover frequency, TOF) increased with the particle size of Pd. Reaction orders in phenol and H 2 and lower activation energies suggest that smaller particles bind the reacting substrates more strongly, leading to higher surface coverages by phenol. But, surprisingly, smaller Pd particles exhibited lower TOFs. The lower activity of the small Pd particles is attributed to lower activation entropies for the strongly bound species. Furthermore, the presence of Ag increased the catalyst activity by decreasing the apparent energy of activation and increasing the coverages of phenol and H 2, without negatively affecting the activation entropy.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [3]
  1. Federal Univ. of Uberlandia (Brazil). School of Chemical Engineering
  2. National Inst. of Technology, Rio de Janeiro (Brazil). Division Catalysis and Chemical Processes
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis
Publication Date:
Report Number(s):
PNNL-SA-125711
Journal ID: ISSN 0926-860X; PII: S0926860X17303757
Grant/Contract Number:
AC05-76RL01830; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Applied Catalysis. A, General
Additional Journal Information:
Journal Volume: 548; Journal ID: ISSN 0926-860X
Publisher:
Elsevier
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1390560