Highly Selective Syngas/H2 Production via Partial Oxidation of CH4 Using (Ni, Co and Ni–Co)/ZrO2–Al2O3 Catalysts: Influence of Calcination Temperature

In this study, Ni, Co and Ni–Co catalysts supported on binary oxide ZrO2–Al2O3 were synthesized by sol-gel method and characterized by means of various analytical techniques such as XRD, BET, TPR, TPD, TGA, SEM, and TEM. This catalytic system was then tested for syngas respective H2 production via partial oxidation of methane at 700 °C and 800 °C. The influence of calcination temperatures was studied and their impact on catalytic activity and stability was evaluated. It was observed that increasing the calcination temperature from 550 °C to 800 °C and addition of ZrO2 to Al2O3 enhances Ni metal-support interaction. This increases the catalytic activity and sintering resistance. Furthermore, ZrO2 provides higher oxygen storage capacity and stronger Lewis basicity which contributed to coke suppression, eventually leading to a more stable catalyst. It was also observed that, contrary to bimetallic catalysts, monometallic catalysts exhibit higher activity with higher calcination temperature. At the same time, Co and Ni–Co-based catalysts exhibit higher activity than Ni-based catalysts which was not expected. The Co-based catalyst calcined at 800 °C demonstrated excellent stability over 24 h on stream. In general, all catalysts demonstrated high CH4 conversion and exceptionally high selectivity to H2 (~98%) at 700 °C

Influence of Nature Support on Methane and CO2 Conversion in a Dry Reforming Reaction over Nickel-Supported Catalysts

A promising method to reduce global warming has been methane reforming with CO2, as it combines two greenhouse gases to obtain useful products. In this study, Ni-supported catalysts were synthesized using the wet impregnation method to obtain 5%Ni/Al2O3(SA-5239), 5%Ni/Al2O3(SA-6175), 5%Ni/SiO2, 5%Ni/MCM41, and 5%Ni/SBA15. The catalysts were tested in dry reforming of methane at 700 °C, 1 atm, and a space velocity of 39,000 mL/gcat h, to study the interaction of Ni with the supports, and evaluation was based on CH4 and CO2 conversions. 5%Ni/Al2O3(SA-6175) and 5%Ni/SiO2 gave the highest conversion of CH4 (78 and 75%, respectively) and CO2 (84 and 82%, respectively). The catalysts were characterized by some techniques. Ni phases were identified by X-ray diffraction patterns. Brunauer–Emmett–Teller analysis showed different surface areas of the catalysts with the least being 4 m2/g and the highest 668 m2/g belonging to 5%Ni/Al2O3(SA-5239) and 5%Ni/SBA15, respectively. The reduction profiles revealed weak NiO-supports interaction for 5%Ni/Al2O3(SA-5239), 5%Ni/MCM41, and 5%Ni/SBA15; while strong interaction was observed in 5%Ni/Al2O3(SA-6175) and 5%Ni/SiO2. The 5%Ni/Al2O3(SA-6175) and 5%Ni/SiO2 were close with respect to performance; however, the former had a higher amount of carbon deposit, which is mostly graphitic, according to the conducted thermal analysis. Carbon deposits on 5%Ni/SiO2 were mainly atomic in nature

Assessment of Ailanthus altissima seed oil as a potential source for biodiesel production using nickel oxide nanoparticles catalyst

The identification of suitable non-edible plant feedstock is crucial not only to meet energy demands but also to be environmentally friendly. This study aimed to synthesize nickel oxide (NiO) nanoparticles and use these for synthesizing biodiesel from the non-edible feedstock Ailanthus altissima. The confirmation of NiO synthesis and its characteristics were studied using XRD and SEM. The biodiesel synthesis and its physicochemical characteristics were confirmed using GC–MS, NMR, and FT-IR spectroscopies. The fuel characteristics were examined using ASTM standard procedures. The results confirmed that the nanoparticles were crystalline, spherical to cuboidal in shape, and had an average diameter of 24 nm. The suitable set of parameters for the optimum biodiesel yield (95 %) was the oil-to-methanol ratio of 1:24, 25 mg of catalyst, 60 °C temperature, and a reaction time of 90 min. The majority of the fuel's characteristics fell within ASTM D-6751 acceptable ranges. 14 distinct kinds of FAMEs are present, according to the GC–MS results. The FT-IR spectra confirmed the successful synthesis of biodiesel, which displayed significant peaks for several functional groups. 1H NMR and 13C NMR spectrums confirm the conversion of biodiesel synthesis. The environmental friendliness of AAB (Ailanthus altissima biodiesel) and its competitiveness as a feedstock for biodiesel production on a commercial scale are confirmed by its physicochemical properties.<br/

Effect of Pressure on Na0.5La0.5Ni0.3Al0.7O2.5 Perovskite Catalyst for Dry Reforming of CH4

In this paper, a comprehensive study was carried out on the application of perovskite catalyst in dry reforming of CH4. The perovskite catalyst was prepared using a sol&ndash;gel method. The prepared samples were characterized by N2 adsorption/desorption, TPR, XRD, CO2-TPD, TGA, TPO, Raman, and SEM techniques. In addition, the effect of operating pressure, namely, 1 bar, 3 bar, 5 bar, and 7 bar, temperature (500&ndash;800 &deg;C) was evaluated. The characterization results indicated that catalysts operated at 1 bar, gas hourly space velocity of 84000 (mL/g/h) gave the best catalytic performance. CH4 and CO2 conversions of 77 and 80% were obtained at 1 bar and at 700 &deg;C reaction temperature. The increase of reaction temperatures from 500 &deg;C to 800 &deg;C increased the reaction rate and hence the methane and carbon dioxide conversions were increased. A unity ratio of H2/CO was obtained at 1 bar for temperatures 600 &deg;C and above. Similarly, the time on stream tests, obtained at a 700 &deg;C reaction temperature, showed that the best ratio in terms of the closeness of unity and the stable profile could be attained when the pressure was set to 1 bar. The TGA analysis showed the drop of mass due to oxidation of carbon deposits, which started at 500 &deg;C. The catalyst operated at 1 bar produced the least amount of carbon, equivalent to 35% weight loss, while the 3 and 5 bar operated catalysts generated carbon formation, equivalent to 65% weight loss. However, the 7 bar operated catalyst resulted the highest accumulation of carbon formation, equivalent to 83% weight reduction. Hence, the TGA profile indicated the relative carbon deposition on the catalyst, which was dependent of the operated pressure and hence confirmed the suitability operation pressure of 1 bar. The characterizations of the Raman, EDX, TGA, and TPO all presented the formation of carbon