Investigation of the effect of alumina binder addition to Pd/SO42− − ZrO2 Catalysts during sol−gel synthesis

We have incorporated alumina into palladium catalysts supported on sulfated zirconia (Pd/SZ) during sol-gel synthesis for application in a washcoat for NOx emissions control in natural gas-fired lean-burn engines. In situ incorporation of the adhesivity-enhancing binder, alumina, during the sol-gel synthesis of the Pd/SZ catalyst demonstrated significantly improved NOx reduction activity of the previously reported dual-catalyst bed when compared to the conventional ex situ mode of binder addition in a slurry. The effects of alumina addition during sol-gel synthesis of Pd/SZ on the structural, textural, and chemical properties of the resulting catalyst were examined in this study. The evolution of the crystal phase of zirconia during calcination of the Pd/SZ catalyst with the binder incorporated during the sol-gel process was studied using in situ XRD during calcination under air. Comparison of the crystal phase composition of the binder-free and binder-incorporated samples calcined at 700 and 900 degrees C demonstrated a stabilizing effect on the tetragonal zirconia in the presence of alumina or boehmite dopants. N-2 adsorption experiments at 77 K indicated the presence of slit-shaped multimodal hierarchical pores as a result of sol-gel alumina addition. EPR spectra indicated that sol-gel alumina incorporation affected the nature of the Pd species on the resulting catalyst. Al-27 MAS NMR spectroscopy revealed a strong interaction of the alumina binder with the zirconia support. The possible formation of a zirconia-alumina solid solution was suggested and was further examined using laser Raman spectroscopy. The influence of the alumina dopant in the zirconia matrix on the chemical states of Zr, S, O, and Al was investigated using XPS. Ar+-ion-gun sputtering provided valuable insights into the nature of the alumina-support interaction due to in situ alumina incorporation during the sol-gel synthesis of Pd/SZ catalysts

The Volatile Effect of Conflict Risk on Foreign Investment

The opportunities of investment brought along by the global economic integrity might turn into a threat in an instant and undermine the underlying structures of national economies. It is necessary to analyze the conflict risk properly in terms of both portfolio investment and finance strategies. This is an important step to be included in the process of arriving to a rational decision. In that way, the existing investment risks could be priced more efficiently. It is proved on Collier and Starr models that there is a correlation between the conflict risk and unemployment, economic recession, inflation and fiscal discipline. In brief, the breakdown in the economic parameters increases the conflict risk and a progress occurring in the opposite way, decreases that risk. In this study, it is discussed the effects of the conflict risk for foreign investment availabilities. Keywords: Foreign direct investment; volatile effect; conflict risk; investment climate</p

Wash-Coat Development for Lean-Burn Engine-Exhaust Aftertreatment: Incorporation of Binder to Pd Supported on Sulfated Zirconia

As the environmental regulations are getting more stringent, it is of great importance to develop a catalytic aftertreatment system for natural gas-fired lean-burn engines to reduce the emissions of nitrogen oxides (NOx), unburned hydrocarbons (CH4, C2H6, and C3H8) and carbon monoxide efficiently. We have developed a dual-catalyst aftertreatment system which utilizes the hydrocarbons present in the exhaust streams of lean-burn engines for reducing NOxemissions. The dual-catalyst aftertreatment system is a physical mixture composed of a reduction catalyst, palladium supported on sulfated zirconia (Pd/SZ), and an oxidation catalyst, cobalt supported on ceria. Such a catalytic system which utilizes methane in the exhaust stream offers several advantages considering that the emissions of air-pollutant greenhouse gases are controlled in a single unit without a need of injecting and handling an external reducing agent such as ammonia [1-3]. Development of a catalytically active washcoat for monolith cores is essential for the practical use of this dual-catalyst system. However, if the washcoat adheres poorly to the monolith core, the aftertreatment unit will suffer from the irreversible loss of the catalytically active phase. In order to improve the adhesive properties, conventionally, binders are used in a catalyst slurry. In this study, we have aimed to improve the adhesive properties at the molecular level. For this purpose, alumina, as a binder, was incorporated in situ to the sol-gel medium of Pd/SZ prior to the gelation during synthesis. Samples prepared by this novel approach have shown superior differences in terms of catalytic performance than the samples prepared by the conventional method. Addition of binder before gelation to the sol-gel medium also resulted in changes of textural and structural properties of binder-free samples, and adhesive properties of the washcoat as shown by N2 physisorption, in-situ X-ray diffraction (XRD) calcination, 27Al-NMR, laser RAMAN and infrared spectroscopy, scanning electron microscopy (SEM) and ultrasonication, Water and sulfur tolerance as well as hydrothermal stability of the binder-incorporated catalyst will be presented as well

Effect of High Temperature on Swellable Organically Modified Silica (SOMS) and Its Application for Preferential CO Oxidation in H-2 Rich Environment

Transition metal oxide catalysts tend to deactivate in the presence of moisture during hydrogen purification using preferential oxidation (PROX) of carbon monoxide (CO) . Thus, novel water-tolerant catalysts need to be developed. Herein, the evolution of heat treated swellable organically-modified silica (SOMS), a hydrophobic organic-inorganic hybrid material, has been characterized and applied as a catalyst support for PROX under moisture-rich conditions. While the SOMS-supported cobalt manganese oxide was found to be inactive, drastic improvement in CO conversion was observed for heat treated SOMS (HSOMS) supported catalysts. From thermogravimetric analysis and NMR spectroscopy it was found that SOMS retains its structural properties and hydrophobicity up to 400 degrees C. The performance of these catalysts was improved upon using toluene as the impregnation solvent, which enhanced the support wettability and improved active site deposition. The catalyst supported on HSOMS-400 was found to be more water tolerant than a silica-supported catalyst due to Si-O-Si(CH3)(3) groups retained from hexamethyldisilazane (HMDS) derivatization of SOMS

Cortical networks of dynamic scene category representation in the human brain

Humans have an impressive ability to rapidly process global information in natural scenes to infer their category. Yet, it remains unclear whether and how scene categories observed dynamically in the natural world are represented in cerebral cortex beyond few canonical scene-selective areas. To address this question, here we examined the representation of dynamic visual scenes by recording whole-brain blood oxygenation level-dependent (BOLD) responses while subjects viewed natural movies. We fit voxelwise encoding models to estimate tuning for scene categories that reflect statistical ensembles of objects and actions in the natural world. We find that this scene-category model explains a significant portion of the response variance broadly across cerebral cortex. Cluster analysis of scene-category tuning profiles across cortex reveals nine spatially-segregated networks of brain regions consistently across subjects. These networks show heterogeneous tuning for a diverse set of dynamic scene categories related to navigation, human activity, social interaction, civilization, natural environment, non-human animals, motion-energy, and texture, suggesting that the organization of scene category representation is quite complex