Effect of Active Metal Supported on SiO2 for Selective Hydrogen Production from the Glycerol Steam Reforming Reaction

The performance of nickel, cobalt, and copper supported on silica as catalysts was evaluated for the glycerol steam reforming (GSR) reaction. The samples were characterized by nitrogen-porosimetry according to Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), and inductively coupled plasma atomic emission spectroscopy (ICP-AES), while the deposited carbon on the catalytic surface was measured with a CHN-analyzer. Catalysts were studied in order to investigate the effect of the reaction temperature on (i) glycerol total conversion, (ii) glycerol conversion to gaseous products, (iii) hydrogen selectivity and yield, (iv) selectivity of gaseous products, and (v) selectivity of liquid products. The results showed that the Ni based on silica (Ni/Si) catalyst was more active and produced less liquid effluents than the catalysts that used an active metal such as Co or Cu. Moreover, the H2 yield from the Ni/Si catalyst was very close to the theoretical maximum predicted by thermodynamics, and the CO2 production was favoured in comparison to CO production, which is important for use in fuel cells

The effect of WO3 modification of ZrO2 support on the Ni-catalyzed dry reforming of biogas reaction for syngas production

Summarization: The time-on-stream catalytic performance and stability of 8 wt. % Ni catalyst supported on two commercially available catalytic supports, ZrO2 and 15 wt.% WO3-ZrO2, was investigated under the biogas dry reforming reaction for syngas production, at 750°C and a biogas quality equal to CH4/CO2 = 1.5, that represents a common concentration of real biogas. A number of analytical techniques such as N2 adsorption/desorption (BET method), XRD, H2-TPR, NH3- and CO2-TPD, SEM, ICP, thermal analysis (TGA/DTG) and Raman spectroscopy were used in order to determine textural, structural and other physicochemical properties of the catalytic materials, and the type of carbon deposited on the catalytic surface of spent samples. These techniques were used in an attempt to understand better the effects of WO3-induced modifications on the catalyst morphology, physicochemical properties and catalytic performance. Although Ni dispersion and reducibility characteristics were found superior on the modified Ni/WZr sample than that on Ni/Zr, its dry reforming of methane (DRM) performance was inferior a result attributed to the enhanced acidity and complete loss of the basicity recorded on this catalyst, an effect that competes and finally overshadows the benefits of the other superior properties. Raman studies revealed that the degree of graphitization decreases with the insertion of WO3 in the crystalline structure of the ZrO2 support, as the ID/IG peak intensity ratio is 1.03 for the Ni/Zr and 1.29 for the Ni/WZr catalyst.Presented on: Frontiers in Environmental Scienc

A comparative study of the H2-assisted selective catalytic reduction of nitric oxide by propene over noble metal (Pt, Pd, Ir)/γ-Al2O3 catalysts

Summarization: The impact of H2 as additional reducing agent on the SCR of NO with C3H6 in excess oxygen, was comparatively explored over low noble metal loading (0.5 wt%), Pt/γ-Al2O3, Pd/γ-Al2O3, Ir/γ-Al2O3 catalysts. To gain insight into the role of H2, the reactions NO + C3H6 + O2 (R#1), NO + C3H6 + O2 + H2 (R#2), NO + H2 + O2 (R#3) were employed. In respect to propene oxidation, the Pd > Pt > Ir sequence was obtained under R#1, since they exhibit complete conversion at 220, 250, 325 °C, respectively; all metals exhibit moderate deNOx performances (XNO, <40%). H2 co-presence (R#2) promotes both the NO and C3H6 conversions, which is valid in the whole temperature interval investigated (50-400 °C), being more substantial for Pt/γ-Al2O3 and Ir/γ-Al2O3, less beneficial for Pd/γ-Al2O3. A two-maxima feature is obtained on XNO pattern (at ∼100 and ∼230 °C) of Pt and Pd during R#2. The low temperature maximum-attributed to NO reduction by H2-is substantially more pronounced on Pt than Pd, offering XNO ∼90% and SN2 ∼85%; the high temperature maximum-attributed to NO reduction by C3H6-is higher by ∼15% on both Pt and Pd, in respect to the values obtained during R#1, while SN2 remained unaffected. Different XNO pattern with one maximum is obtained over Ir, implying a synergistic interaction between H2 and C3H6. This synergy is accompanied by a substantial widening of the NO reduction window toward lower temperatures and a considerable increase on both XNO,max and SN2 (from XNO ∼30% with SN2 ∼55% during R#1 to XNO ∼70% with SN2 ∼95% during R#2). The specific features of all reactions and metals employed are comparatively discussed.Presented on: Journal of Environmental Chemical Engineerin