The structure sensitivity of a liquid-phase 1-hexyne hydrogenation was studied using monodispersed nonsupported Pd nanoparticles of 6, 8, 11, 13, and 14 nm diameter. The particles were prepared via a reverse microemulsion water/AOT/isooctane. The size was varied by the water-to-surfactant ratio. A 15-fold TOF increase was observed with increase of the particle diameter from 11 to 14 nm. For particles above 14 nm, TOF approached the value of the Pd black catalyst. It was observed that the selectivity toward 1-hexene did not vary with the particle size and was 96.5% at the conversion of 1-hexyne of 85%. The byproduct distribution was characterized by the ratio of selectivities to 2-hexenes/n-hexane and decreased 5-fold with particle diameter from 6 to 11 nm but remained constant for bigger particles. The experimental results indicate a predominance of a "geometric" nature of the size effect observed during selective 1-hexyne hydrogenation, suggesting that an ensemble of neighboring Pd surface atoms constitutes the active center responsible for hydrogenation.

The catalytic hydrogenation of nitrite in water to nitrogen over Pd-supported on different woven fibrous materials is studied.Low porosity carbon fibers, low porosity D-type glass fibers and composite (glass covered by ␥-aluminia) fibers are used.The dispersion of Pd is compared for different supports at various Pd-loadings and correlated with the catalytic activity. The ammonia as an undesired by-product was also observed and the main parameters suppressing its formation are discussed. A reactor concept based on woven fibrous catalysts is suggested and the main design parameters for the technical application are estimated.

Interaction of N2O at low temperatures (473-603 K) with Fe-ZSM-5 zeolites (Fe, 0.01-2.1 wt %) activated by steaming and/or thermal treatment in He at 1323 K was studied by the transient response method and temperature-programmed desorption (TPD). Diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) of NO adsorbed at room temperature as a probe molecule indicated heterogeneity of surface Fe(II) sites. The most intensive bands were found at 1878 and 1891 cm(-1), characteristic of two types mononitrosyl species assigned to Fe2+(NO) involved in bi- and oligonuclear species. Fast loading of atomic oxygen from N2O on the surface and slower formation of adsorbed NO species were observed. The initial rate of adsorbed NO formation was linearly dependent on the concentration of active Fe sites assigned to bi- and oligonuclear species, evolving oxygen in the TPD at around 630-670 K. The maximal coverage of a zeolite surface by NO was estimated from the TPD of NO at approximately 700 K. This allowed the simulation of the dynamics of the adsorbed NO formation at 523 K, which was consistent with the experiments. The adsorbed NO facilitated the atomic oxygen recombination/desorption, the rate determining step during N2O decomposition to O2 and N2, taking place at temperatures > or =563 K.

The use of glass fibers in the form of woven cloth (GFC), as a new type of catalytic support, was studied for the reduction of aqueous nitrate solutions using a Pd/Cu-GFC catalyst. The activity (per gram Pd) and selectivity to nitrogen were found to be comparable with those found for Pd-Cu catalysts supported on the other carriers. The maximal initial removal activity was found for a catalyst with a Pd/(Pd + Cu) ratio of 0.81. The corresponding activity was 0.7 mmol min −1 (g Pd ) −1 , and the selectivity was 97 mol% at 25 • C and pH 6.5 for initial nitrate concentration of 100 mg l −1 . The selectivity to nitrogen declined at high conversions of nitrate and high pH.

A novel concept of a recycle loop reactor is developed with structured filamentous catalysts integrated as trays in a staged bubble column. The reactor can be operated in batch or continuous mode. Woven fabrics of activated carbon fibres (ACF) were used as support for the Pd catalyst.The loop reactor was tested in the 2-butyne-1,4-diol hydrogenation showing selectivity up to 97% towards 2-butene-1,4-diol at conversions up to 80%. The reactor behaviour was described quantitatively assuming an ideally mixed reactor and Langmuir-Hinshelwood kinetics with weak hydrogen adsorption.Catalyst reuse was demonstrated in multiple runs over a period of 6 months with more than 375 h on stream.