Gasification of Glycerol Over Ni/γ-Al2O3 For Hydrogen Production: Tailoring Catalytic Properties to Control Deactivation

BACKGROUNDA nickel‐based catalyst is active in the dry reforming of methane. However, the nickel‐metal particles' sintering at high reaction temperatures and the rapid catalyst deactivation due to coke deposition are still significant issues.RESULTSA series of catalysts, Ni1‐xCex, was prepared by the sol–gel technique and the synthesized catalysts were used for the methane dry reforming reaction considering various parameters, such as the ceria to nickel ratio, total loading, catalyst calcination, and reduction temperature. The addition of ceria to nickel increased the CH4 and CO2 percent conversion. The catalyst 40Ni0.75Ce0.25/Al2O3 calcined at 700 °C possessed a high conversion of CO2 and CH4. The reduced catalyst (40Ni0.75Ce0.25/Al2O3) showed better catalytic activity than the calcined catalyst. However, the reduced catalyst's performance declined due to coke deposition. The calcined catalyst was more stable than the reduced catalyst. The time‐on‐stream study (up to 16 h) reflected that the percent conversion and yield dropped more sharply for the reduced catalyst (% CO2 Conversion dropped: 100% to 94%) than for the calcined catalyst (% CO2 conversion dropped: 94% to 93%). The accumulation of ceria and support (alumina) increased the catalyst surface area, which improved the overall activity and stability of the catalyst. Scanning Electron Microscopy (SEM) and Raman spectroscopy analyses detected the formation of Multi Walled ‐ Carbon Nanotubes (MW‐CNT) on the used catalyst. They also show the formation of a smaller diameter of MW‐CNT (60–70 nm) over the calcined catalyst than the reduced catalyst (80–139 nm).CONCLUSIONThe calcined catalyst, 40Ni0.75Ce0.25/Al2O3–700 °C, was very active with high methane (91%) and CO2 (94%) conversions; also, the reduced catalyst was active and possessed high methane (88%) and CO2 (100%) conversions at low reaction temperatures. Overall, the calcined catalyst was comparatively more stable than the reduced catalyst. © 2022 Society of Chemical Industry (SCI).

Nanosized barium titanate powders were synthesized by a hydrothermal method. The effect of titania precursors on the phase transition of BaTiO3 with respect to Ba/Ti ratio, reaction temperature, reaction time, and calcination temperature was investigated. The synthesized materials were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. BaTiO3 in pure cubic phase with spherical morphology was observed with a lower calcination temperature, Ba/Ti ratio, reaction temperature, and time. Increase in the tetragonal phase was ascertained in treatments at higher reaction temperature with a longer reaction time. The lattice hydroxyl release is believed to be the reason for tetragonality at high reaction and calcination temperatures. To prepare tetragonal BaTiO3 using HClO4-TiO2, the optimum synthesis conditions viz., Ba/Ti ratio, reaction temperature, and reaction time, are 1.2, 160 °C, and 3 h, respectively, at a calcination temperature of 1150 °C. The reaction time and reaction temperature for the cubic−tetragonal phase transformation of BaTiO3 shifted toward shorter reaction time and lower reaction temperature when TiO2 was synthesized by hydrolysis using HClO4 as the acid catalyst.

Carbon nanotubes (CNTs) were synthesized in the temperature range of 500–700°C over cobalt (Co)- and molybdenum (Mo)-impregnated CaCO3 catalysts using acetylene gas. The effects of Co-Mo/CaCO3 catalyst's calcination temperature and Co/Mo weight ratio on the carbon deposition rate were investigated. The synthesized CNTs were multiwalled nanotubes with variable outer diameters. They exhibited Type II isotherm, and their surface areas were in the range of 24.8–89.9 m2/g. It was concluded that the Co/Mo ratio in the catalyst played an important role in the structure of carbon, Co was more active than Mo for the CNT growth, and the carbon deposition rate increased with an increase in the initial acetylene composition in argon, Co/Mo ratio, and the reaction and calcination temperatures. The highest carbon deposition rate was produced at a reaction temperature of 700°C over the Co-Mo/CaCO3 catalyst synthesized at a Co/Mo ratio of 6 and a calcination temperature of 750°C.

Influence of calcination temperature on the evolution of Fe species over Fe-SSZ-13 catalyst for the NH3-SCR of NO

Structural and Surface Properties of CuO-ZnO-Cr2O3 Catalysts and Their Relationship with Selectivity to Higher Alcohol Synthesis

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Supported bimetallic gold-palladium (AuPd) nanomaterials have been extensively studied as highly active and selective nanocatalysts for oxidation reactions. For long-term viability, optimizing synthesis and reaction parameters is essential for utilizing noble-based materials once they are expensive to produce on a large scale. For that reason, using a performance-focused strategy like a multivariate experimental design is an optimal solution for simultaneously investigating the effects of different parameters and implementing such materials in business activities. Therefore, herein, we report a systematic multivariate optimization of model AuPd/SiO2 nanocatalysts for selective benzyl alcohol oxidation in solvent-free sustainable conditions, which allows for the evaluation of the impact of the material synthesis and reaction conditions on the process and optimization of reaction and calcination temperatures. Our multivariate analysis shows that the calcination temperature has considerably impacted the structural properties of gold nanoparticles; still, these changes did not produce a pronounced effect on the material’s catalytic properties. On the other hand, the physical variables of reaction time and temperature had a more significant influence on both conversion and selectivity. An 18% conversion of benzyl alcohol with a benzaldehyde selectivity of 93% was achieved under a 562 ◦C catalyst calcination temperature, 100 ◦C reaction temperature, and 4 h of reaction time.

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Oxidation of NO over cobalt oxide supported on mesoporous silica