Abstract: The NO2 removal performance of Fe-modified H-BEA and H-ZSM-5 has been investigated in detail by means of in situ and operando FTIR spectroscopy. The surface characterization using NO2 and NO as probe molecules revealed important contributions of redox processes involving Fe3+-OH and/or α-oxygen species as well as Fe2+-NO species. In these anhydrous conditions, the NO2 storage performance is mainly due to the disproportion of NO2 leading to NO+ and nitrate species. However, under flow and in the presence of humidity, and thus in more realistic conditions, nitrates and NO+ formation are suppressed. The main mechanism responsible for the wet NO2 removal consists in the formation of both adsorbed nitric acid and gaseous NO. According to the proposed mechanism, a strong positive water-effect is established: the total suppression of NO2 in the presence of humidity together with the formation of NO, which is less toxic than NO2, makes the investigated zeolites promising candidates for efficient materials used in indoor air treatment.

Abstract: Catalytic materials and heterogeneous catalysis Heterogeneous catalysis is behind most of the principles of green chemistry: energy saving processes, atom efficiency, use of renewable feedstock, process intensification, cleaning processes. For that purposes, the design of new catalytic materials is in high demand: materials with mastered and hierarchically ordered porosity, materials allowing catalysis on single site and on stabilized nanosized oxide or metal particles.

Abstract: The synthesis on the gram scale and characterization of a series of flexible functionalized iron terephthalate MIL-53(Fe) type solids are reported. Chemical groups of various polarities, hydrophilicities, and acidities (-Cl, -Br, -CF(3), -CH(3), -NH(2), -OH, -CO(2)H) were introduced through the aromatic linker, to systematically modify the pore surface. X-ray powder diffraction (XRPD), molecular simulations, thermogravimetric analyses, and in situ IR and (57)Fe Mossbauer spectrometries indicate some similarities with the pristine MIL-53(Fe) solid, with the adoption of the narrow pore form for all solids in both the hydrated and dry forms. Combined XRPD and computational structure determinations allow concluding that the geometry of the pore opening is predominantly correlated with the intraframework interactions rather than the steric hindrance of the substituent. Only (MIL-53(Fe)-(CF(3))(2)) exhibits a nitrogen accessible porosity (S(BET) approximately 100 m(2) g(-1)). The adsorption of some liquids leads to pore openings showing some very specific behaviors depending on the guest-MIL-53(Fe) framework interactions, which can be related to the energy difference between the narrow and large pore forms evaluated by molecular simulation.

Abstract: Fe–FER zeolites were characterized by FTIR spectroscopy of adsorbed CO and NO. Two aged samples (Fe–FER-1 and Fe–FER-4 with Fe content of 1.1 and 3.7 wt%, respectively) and one freshly prepared 57Fe rich sample (57Fe–FER, designed for Mössbauer studies and containing 1.5 wt% Fe) were studied. Both CO and NO are adsorbed onto Fe2+ cations and have different sensitivities to their location and/or coordination state. CO adsorption on Fe–FER-1 reveals two kinds of Fe2+ sites with the respective complexes observed at 2195 and 2189 cm−1. The principal carbonyls (2195 cm−1) are easily converted into dicarbonyls (2188 cm−1) at low temperature and high CO equilibrium pressure. NO is less sensitive than CO to the environment of Fe2+ ions and NO adsorption gives rise to a single band at 1878 cm−1. However, careful analysis reveals that this band consists of two closely located components. With the Fe–FER-4 sample a third family of iron sites was detected by CO at 2196 cm−1. These carbonyl species are stepwise converted to di- (not, vert, similar2188 cm−1) and tricarbonyls (not, vert, similar2180 cm−1). With these sites NO forms another nitrosyls clearly detected at 1895 cm−1. The latter are converted with time into polynitrosyls. These new sites are very sensitive to the preliminary treatment and easily change their oxidation state, forming Fe2+/Fe3+ redox couples. The sample preliminary treated with oxygen at 673 K is characterized by Fe3+–OH groups (3674 cm−1) and reactive oxygen that produces carbonates when reacting with CO, and NO+ when interacting with NO. Adsorption of NO on a freshly prepared 57Fe–FER sample confirms the presence of the three distinct Fe2+ sites which is consistent with Mössbauer data. Finally, summarizing all the data, location of the different sites inside the FER structure is proposed. The results obtained are discussed in relation with the catalytic performance of Fe–FER.

Abstract: Two series of (Co)Mo/Al2O3 catalysts were compared: one set was prepared with a constant amount of Mo, and various amounts of Co (from 0 to 4.5%), the second one containing the same amount of metals, but with ethylene diamino tetraacetic acid (EDTA) addition (27wt%). The sulfided catalysts were characterized by IR spectroscopy of adsorbed CO. IR reveals that EDTA leads to a strong increase in the concentration of Co-promoted sites. EDTA has also a significant positive effect on thiophene hydrodesulfurization at atmospheric pressure, and 2,6-dimethylaniline hydrodenitrogenation at high pressure. Combination of spectroscopic and activity data shows that EDTA chiefly increases the amount of promoted sites having lower average intrinsic activities. This decrease in intrinsic activity should be due to a change of the site structure. Two models can be proposed to account for EDTA effect on the site structure such as the formation of type II slabs or that of nitrogeno-sulfide Co-promoted sites, “CoMoSN”.

Abstract: Arrangements associating three aluminium atoms in dealuminated Y zeolites are for the first time detected using a combination of multiple-quantum MAS (MQMAS) and 2D double-quantum homonuclear NMR correlation spectroscopy. From these results, we propose a model describing the enhanced Brd acid sites in dealuminated Y zeolite, consisting in a configuration where framework aluminium pairs are interacting with cationic extra-framework aluminium atoms.

Abstract: This paper reviews some of the aspects of combining in situ/operando infrared spectroscopy and kinetic studies. The strengths and limitations of various methods are discussed based on examples found in the literature and especially taken from the present author. A clear warning is made that qualitative or semi-quantitative analyses can easily result in unimportant surface species being mistaken for true reaction intermediates.

Abstract: Catalysts containing ionic liquid phase immobilised on chitosan are successfully applied to the palladium-catalysed allylation reaction. A strong influence of the conditioning of chitosan not only on the activity and enantioselectivity but also on the recyclability and reusability of the catalyst is demonstrated.

Abstract: The adsorption geometries, energies, and vibrational frequencies of methanol on MgO defective surfaces
have been calculated by periodic DFT simulations. The results are very comparable with those obtained with
water and are also in very good accordance with microcalorimetry and infrared experiments. At low coverage,
the dissociation is observed on all defects involving ions in low coordinations. Over and above the coordination
number of surface ions, the adsorption energy is strongly governed by the surface topology: dissociation on
confined sites gives rise to methoxy groups highly stabilized by bridging two or even three cations. The
occurrence of such very strong sites on MgO powder is confirmed by microcalorimetry. The dissociation
ability depends on the methanol coverage because it modifies the surface relaxation and the network of H
bonds, resulting, for a given defect, in similar adsorption energies for molecular and dissociated species at
high coverage. This explains why there are more strong sites (quantified by microcalorimetry) than dissociating
sites (quantified by infrared).

Abstract: Jump to it! 2D IR pressure-jump spectroscopy of adsorbed CO can be used to assess the accessibility and location of platinum nanoparticles supported on a zeolite and investigate the behavior of Pt atoms after thermal treatment (activation, catalytic reaction, sintering). Different Pt nanoparticle sintering mechanisms were observed in the mesopores and on the external surface of the ZSM-5 support (see picture; HF=high and LF=low frequency).

Abstract: Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) has been employed along with chemical and isotope transients to study the catalytic CO hydrogenation over Co/MgO catalysts in a single fixed-bed reactor at T ) 523 K and ambient pressure conditions (H2/CO ) 3). According to the operando DRIFTS measurements, the catalyst surface contains hydroxyl groups, adsorbed CO, formate, and methylene groups in the steady-state of the reaction. Transient experiments following fast changes in the feed (chemical transient kinetics, CTK) or isotope composition (steady-state isotopic transient kinetic analysis, SSITKA) have been
carried out during DRIFTS and demonstrate that the formate/methylene “seen by DRIFTS” plays no role as imminent intermediates of the ambient pressure Fischer-Tropsch (FT) reaction. The SSITKA experiments (replacing 12CO by 13CO) show that the exchange rate of formate/methylene is significantly lower than that of ethane, which is one of the main reaction products of CO hydrogenation (followed by mass spectrometry). Formate is most probably bound as bidentate μ2-species to MgO or at the Co/MgO interface, while methylene stands for skeleton CH2 in either hydrocarbon or carboxylate.