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Dedicated to the Catalysis Society of Japan on the occasion of the 50th anniversary Various powerful in situ spectroscopic methods and their combinations have been developed to clarify and establish relations between catalytic activity and the atomic-scale environment of catalytic active sites, particularly under actual working conditions.[1] As demonstrated recently, the addition of the space-domain into typical time-domain spectroscopy allows a deeper understanding of structural effects on catalytic activity within crystals.[2] Another relevant space domain in heterogeneous catalysis is that along the axial and radial directions in a catalyst bed of a continuous fixed-bed reactor, where prominent concentration and temperature gradients are known to exist.[3] For such integral-type reactors, knowledge of concentration and temperature profiles, as well as of structural changes along the catalyst bed caused by them, is crucial for gaining insight into the governing mechanisms and for improving catalytic performance.Herein, a time-resolved study of NO x storage reduction is presented, with the addition of spatial resolution along the catalyst bed using combined diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and Raman spectroscopy. The combined approach, employing a switch between DRIFTS and Raman spectroscopy within a single setup is known to yield rich chemical information. [4] In this study, simultaneous detections of the two spectroscopic methods within a single setup are achieved which give access to both surface and bulk information because of the greatly different local sensitivity of the two methods. Particular attention is given to the position-dependent dynamic surface and bulk processes along the catalyst bed, and their relation to the overall catalytic activity. NO x storage reduction (NSR) has garnered considerable attention, owing to its NO x reduction capability in oxygenrich atmospheres and its technical potential. Considerable effort has been undertaken in the elucidation of its underlying mechanism.[5] NSR utilizes periodic switching between fuellean (oxidative atmosphere) and fuel-rich (reductive atmosphere) conditions of engines. Generally, chemical processes occurring during the two distinct periods of NSR are summarized as follows: 1) During fuel-lean periods, NO is oxidized to NO 2 over a noble metal component, such as Pt, and stored on an alkali or alkaline-earth metal component of the catalysts, such as Ba (only Ba is mentioned hereafter), in the form of nitrates. 2) During fuel-rich periods, the stored NO x is released and reduced to N 2 over the noble metal, and the Ba component is regenerated for NO x storage. Several storage and reduction mechanisms have been proposed and their relevance is still a matter of active discussion. This ambiguity is, to a large extent, caused by the difficult identification of relevant species by using solely infrared [6,7] or Raman [8] spectroscopy. A variety of Ba species, such as nitrite, nitrate, carbonate, oxide, peroxide, and hydro...

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Chemoselective platinum-catalyzed liquid-phase hydrogenation of aromatic ketones is an important reaction in the production of fine chemicals and pharmaceuticals. A typical example of this class of reactions is the hydrogenation of acetophenone (AP) over a Pt/Al 2 O 3 catalyst. We investigated the adsorption behavior of the different reaction components and their reaction pathways using in situ attenuated total reflection infrared spectroscopy in combination with modulation excitation spectroscopy and phase sensitive detection. AP adsorbed on both Pt and the alumina support. On Pt, AP adsorbed in the η 1 (O) configuration prevailed, whereas on alumina, AP bound to Lewis acid sites was predominant. In the presence of hydrogen, η 1 (O) AP adsorbed on Pt was hydrogenated to the main product, 1-phenylethanol (PE), with high selectivity (82.5%). The produced PE was more strongly adsorbed on the alumina support than on Pt, leading to replacement of AP and accumulation of PE on alumina. Co-adsorption experiments of AP with its products PE, 1-cyclohexylethanol, and ethylbenzene revealed that AP adsorbed in the η 1 (O) configuration was always the prevalent adsorption mode of AP on Pt, which may partly explain the high selectivity to PE observed. Co-adsorption of AP and CO did not significantly affect the adsorption of AP; however, CO adsorption strongly suppressed the adsorption and dissociation of H 2 . The studies revealed a striking difference in the selectivity behavior between the gas-phase and liquid-phase hydrogenation. Although in the gas-phase hydrogenation of AP, a significant effect of decomposition/hydrogenolysis products on the chemoselectivity of AP hydrogenation was reported, these fragmentation reactions were barely observed in the liquid phase.

Malignant peripheral nerve sheath tumor (MPNST) can be difficult to diagnose because it lacks specific immunohistochemical markers. S-100, which is a useful marker of MPNST, has limited diagnostic utility. Recent studies suggest that nestin, which is an intermediate filament protein, is expressed in neuroectodermal stem cells. The diagnostic utility of immunostains for nestin and three other neural markers (S-100, CD56 and protein gene product 9.5 (PGP 9.5)) were evaluated in 35 cases of MPNST and in other spindle cell tumors. All MPNST cases were strongly positive for nestin and had cytoplasmic staining. Stains for S-100, CD56, and PGP 9.5 were positive in fewer cases (17/35, 11/35, and 29/35 cases, respectively), and had less extensive staining. Nestin was negative in 10/10 leiomyomas, and weak nestin expression was seen in 10/10 schwannomas, 3/10 neurofibromas, 2/8 synovial sarcomas, 2/10 liposarcomas, 4/7 carcinosarcomas and 3/7 malignant fibrous histiocytomas. In contrast, strong nestin positivity was seen in 10/10 rhabdomyosarcomas, 15/19 leiomyosarcomas, and 9/9 desmoplastic melanomas. Nestin is more sensitive for MPNST than other neural markers and immunostains for nestin in combination with other markers could be useful in the diagnosis of MPNST.

The adsorption states of N2 and H2 on MgO-supported Ru nanoparticles under conditions close to those of ammonia synthesis (AS; 1 atm, 250 °C) were uncovered by modulation–excitation infrared spectroscopy and density functional theory calculations using a nanoscale Ru particle model. The two most intense N2 adsorption peaks corresponded to the vertical chemisorption of N2 on the nanoparticle’s top and bridge sites, while the remaining peaks were assigned to horizontally adsorbed N2 in view of the site heterogeneity of Ru nanoparticles. Long-term observations showed that vertically adsorbed N2 molecules gradually migrated from the top sites to the bridge sites. Compared to those adsorbed vertically, N2 molecules adsorbed horizontally exhibited a lower dipole moment, an increased NN bond distance, and a decreased NN bond order (i.e., were activated), which was ascribed to enhanced Ru-to-N charge transfer. H2 molecules were preferentially adsorbed horizontally on top sites and then rapidly dissociated to afford strongly surface-bound H atoms and thus block the active sites of Ru nanoparticles. Our results clarify the controversial adsorption/desorption behavior of N2 and H2 on AS catalysts and facilitate their further development.