Vulnerability to natural disasters in Serbia: spatial and temporal comparison

The frequency of natural disasters and the extent of their consequences at a global level are constantly increasing. This trend is partially caused by increased population vulnerability, which implies the degree of population vulnerability due to high magnitude natural processes. This paper presents an analysis of vulnerability to natural disaster in Serbia in the second half of the twentieth and the early twenty-first century. Vulnerability changes were traced on the basis of demographic–economic indicators derived from statistical data for local government units (municipalities) provided by the Statistical Office of the Republic of Serbia. Calculations were performed in the geographical information system environment. The results of the study show that spatial and temporal vulnerability variations are causally correlated with changes in the selected components. Significant rise of vulnerability is related to urban areas, while lower values are characteristic for other areas of Serbia; this is primarily a consequence of different population density

Ni alumina-based catalyst for sorption enhanced reforming - Effect of calcination temperature

Effect of calcination temperature (350 °C – 850 °C) on the physicochemical properties as well as catalytic performance of Ni-based catalyst for the hydrogen production via steam methane reforming (SMR) and sorption enhanced reforming (SER) has been investigated. Catalyst calcined at highest temperature (850 °C) shows formation of NiAl2O4 confirmed by XRD. Consequently, a much higher reduction temperature (875 °C) is required to reduce this Ni aluminate spinel to an active Ni catalyst. Catalyst calcined at highest temperature (850 °C) showed much higher CH4 conversion and H2 production in SMR compared to the catalysts calcined at lower temperatures. In addition, higher CH4 conversion and H2 production was observed for the 15%Ni/alumina_850 catalyst after aging (long exposure to steam and high temperature) compared to commercial reforming catalyst. Finally, a much better stability is observed for the 15%Ni/alumina_850 catalyst compared to the commercial reforming catalyst after 100 SER/regeneration cycles under relevant reaction conditions. The formation of NiAl2O4 during high temperature calcination plays a vital role in the robustness and stability of the Ni-based catalysts and can be useful synthesis procedure for increasing the catalyst lifetime

Palladium-copper bimetallic surfaces as electrocatalysts for the ethanol oxidation in an alkaline medium

Two types of Cu-modified Pd catalysts supported on high area carbon were prepared: Pd nanoparticles modified with a sub-monolayer of underpotentially deposited Cu (Cu@Pd/C) and Pd-Cu alloy nanoparticles (Pd-Cu/C), and examined for the ethanol oxidation reaction (EOR) in alkaline solution. The catalysts were characterized by energy-dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy, as well as cyclic voltammetry. As reference catalysts, Pd/C and Pt/C were used. The electrochemically active surface area of all samples was determined from COads and Cuupd desorption and Pd oxide reduction, and used to assess their intrinsic activity for EOR. Intimate contact of Pd with Cu atoms enhanced its activity, regardless of the type of bimetal catalyst. The atomic Pd:Cu ratio between 2:1 and 4:1 appears to be optimal for high activity. The most active catalyst under the potentiodynamic conditions was Cu@Pd/C with θ(Cu) = 0.21,although Pd-Cu/C was superior during the potentiostatic test. All bimetallic catalysts surpassed Pd/C in mass activity. The EOR activity of Pt/C was higher compared to Pd-based catalysts at low potentials, both in terms of specific and mass activity, but with a significant decline over a 30-min potentiostatic stability test