Iridium(O) nanoparticles dispersed in zeolite framework: A highly active and long-lived green nanocatalyst for-the hydrogenation of neat aromatics at room temperature

Zahmakıran, Mehmet
Özkar, Saim
The complete hydrogenation of aromatic molecules is one of the key transformation employed in the synthetic and petroleum chemistry. Described herein is a new catalytic nanomaterial for the hydrogenation of neat aromatics under mild conditions. A novel nanocatalyst, consisting of iridium(O) nanoparticles stabilized by zeolite with EAU framework could reproducibly been prepared from the reduction of iridium(III)-exchanged zeolite in an aqueous sodium borohydride solution at room temperature and characterized by ICP-MS, P-XRD, HRTEM, XPS, N-2-Ads.-Des., and P(C6H11)(3) poisoning. The results reveal the formation of iridium(O) nanoparticles of 5.8 +/- 2.1 nm size dispersed on the external surface along with iridium(O) nanolclusters in cavities of zeolite-Y whereby the host matrix remains intact. The resulting iridium(O) nanoparticles were employed as heterogeneous catalyst in the hydrogenation of various aromatic substrates (benzene, toluene, o-xylene and mesitylene) in the solvent-free systems at room temperature and 3 bar initial Hy pressure. They are highly active catalyst in the hydrogenation of neat aromatics, such as they can completely hydrogenate benzene to cyclohexane with an initial turnover frequency value of TOE= 3215 h(-1). Moreover, they show high durability against to leaching and sintering throughout the catalytic runs, which make them reusable catalyst. More importantly, testing the catalytic lifetime of our iridium(O) nanoparticles showed that they provide previously unprecedented total turnover number of TO = 197,000 over 92 h before deactivation in the hydrogenation of benzene at room temperature and 3 bar initial H-2 pressure.


Iridium(0) nanocluster, acid-assisted catalysis of neat acetone hydrogenation at room temperature: Exceptional activity, catalyst lifetime, and selectivity at complete conversion
Özkar, Saim (American Chemical Society (ACS), 2005-04-06)
Acetone hydrogenation catalysis is important in applications such as heat pumps and fuel cells or in fulfilling the sizable demand for the product of selective acetone hydrogenation, 2-propanol. Reported herein is the discovery of a superior acetone hydrogenation catalyst- superior in terms of activity at low temperature, selectivity at complete conversion, and total catalyst lifetime. The new catalyst system consists of lr(0)(n) nanoclusters plus HCI easily and reproducibly formed from commercially availab...
Ruthenium(0) nanoclusters stabilized by zeolite framework as superb catalyst for the hydrogenation of neat benzene under mild conditions: Additional studies including cation site occupancy, catalytic activity, lifetime, reusability and poisoning
Zahmakiran, Mehmet; Kodaira, Tetsuya; Özkar, Saim (Elsevier BV, 2010-06-07)
The hydrogenation of arenes is an ubiquitous chemical transformation used in both the petrochemical and specialty industry and important for the generation of clean diesel fuels. In a recent communication (M. Zahmakiran, S. Ozkar, Langmuir 24 (2008) 7065) we have reported the preliminary results for the unprecedented catalytic activity of zeolite framework stabilized ruthenium(0) nanoclusters in the hydrogenation of neat benzene (TOF approximate to 1040 mol benzene/mol Ru.h) under mild conditions (22 degree...
Intrazeolite cobalt(0) nanoclusters as low-cost and reusable catalyst for hydrogen generation from the hydrolysis of sodium borohydride
Rakap, Murat; Özkar, Saim (Elsevier BV, 2009-09-07)
Intrazeolite cobalt(0) nanoclusters were prepared by ion-exchange of Co2+ ions with the extraframework Na+ ions in the zeolite-Y followed by the reduction of Co2+ ions in the supercages of zeolite-Y with sodium borohydride at room temperature. The intrazeolite cobalt(0) nanoclusters were isolated as solid materials and characterized by ICP-OES, XRD, HRTEM, SEM, XPS, Raman spectroscopy and N-2 adsorption technique. The catalytic activities of intrazeolite cobalt(0) nanoclusters in the hydrolysis reaction of ...
Rhodium(0) nanoparticles supported on nanosilica: Highly active and long lived catalyst in hydrogen generation from the methanolysis of ammonia borane
Ozhava, Derya; Özkar, Saim (Elsevier BV, 2016-02-01)
Nanosilica stabilized rhodium(0) nanoparticles (Rh(0)/nanoSiO(2)), in situ formed from the reduction of rhodium(II) octanoate impregnated on the surface of nanosilica, are active catalyst in hydrogen generation from the methanolysis of ammonia borane at room temperature. Monitoring the hydrogen evolution enables us to follow the kinetics of nanoparticles formation. The resulting sigmoidal kinetic curves are analyzed by using the 2-step mechanism of the slow, continuous nucleation and autocatalytic surface g...
Hydroxyapatite supported ruthenium(0) nanoparticles catalyst in hydrolytic dehydrogenation of ammonia borane: Insight to the nanoparticles formation and hydrogen evolution kinetics
Akbayrak, Serdar; Erdek, Pelin; Özkar, Saim (Elsevier BV, 2013-10-01)
When a solution of ammonia borane is added to the suspension of ruthenium(III) ions supported on hydroxyapatite, both reduction of ruthenium(III) to ruthenium(0) nanoparticles and hydrogen release from the hydrolysis of ammonia borane occur concomitantly at room temperature. Using the hydrogen evolution from the hydrolysis of ammonia borane as reporter reaction provides valuable insights to the formation kinetics of ruthenium(0) nanoparticles. Thus, the rate constants for the slow nucleation and autocatalyt...
Citation Formats
Y. TONBUL, M. Zahmakıran, and S. Özkar, “Iridium(O) nanoparticles dispersed in zeolite framework: A highly active and long-lived green nanocatalyst for-the hydrogenation of neat aromatics at room temperature,” APPLIED CATALYSIS B-ENVIRONMENTAL, pp. 466–472, 2014, Accessed: 00, 2020. [Online]. Available: