Ru/hierarchical HZSM-5 zeolite as efficient bi-functional adsorbent/catalyst for bulky aromatic VOCs elimination

This study focused on the elimination of bulky aromatic VOCs by adsorption/combustion in humid conditions using Ru/hierarchical HZSM-5 zeolites as adsorbent and catalyst. Compared with Ru/conventional HZSM-5 zeolite, Ru/hierarchical HZSM-5 showed increased external surface and mesoporous volume, shortened diffusion length and enhanced low-temperature reducibility. Adsorption experiments demonstrated that Ru/hierarchical HZSM-5 zeolite was a very efficient adsorbent for the removal of bulky aromatic VOCs. In addition, the catalytic activity of as-prepared composite in VOCs combustion showed good correlations with their textural characteristics. The value of turnover frequency (r(ToF)) of Ru/hierarchical HZSM-5 was about twice, three and four times to that of Ru/conventional HZSM-5 toward toluene, o-xylene and TMB combustion, respectively, which indicated Ru/hierarchical HZSM-5 zeolites had more significant performance for catalyzing combustion of bulkier molecule. More importantly, Ru/hierarchical HZSM-5 showed the efficient bi-functional performance during the adsorption/combustion cycling process for bulky aromatic VOCs. In addition, the good carbon balance has been kept for each cycle without the production of secondary pollutants. (C) 2017 Elsevier Inc. All rights reserved.