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

Abstract

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–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 (500–800 °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 °C reaction temperature. The increase of reaction temperatures from 500 °C to 800 °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 °C and above. Similarly, the time on stream tests, obtained at a 700 °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 °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.

The influence of Ni stability, redox, and lattice oxygen capacity on catalytic hydrogen production via methane dry reforming in innovative metal oxide systems

“…In addition, this structure allows for numerous substitutions at the B site (Ni) by the cations Mg, Al, Mn, Fe, Co, Fe, Cu, Zn, Ce, Rh, and Ru, as well as at the A site (La) by the following cations Ca, Ba, Sr, Ce, and Pr 7,12,14–40 . Substitution of A site ions with those of a lower oxidation state can affect the stability in a reducing environment and the movement of oxygen ion vacancies.…”

Effect of Ni-Co Addition on Pd Promoted Al2o3 Catalysts for Dry Reforming of Methane

“…relatively inert and often leads to catalyst deactivation by blocking active sites on the surface. Depending on the Raman shift values, the carbon formed in DRM is classified as defective carbon or amorphous carbon (D-band:1360 cm − 1 ) and graphitic carbon (G-band: 1590 cm − 1 )[31,37]. Additionally, the intensity ratio of the Dband (I D ) to Gband (I G ) provides the defective nature of the carbon, if the I D /I G ratio is high, then the carbon deposited on the catalyst surface is highly defective carbon.The order of defective carbon (I D /I G ) on the spent catalyst is varied depending on the bi-metallic compositions and is calculated to be 2.24, 1.34, 2.05, 1.47, and 0.91 for 5 Ni, 3.75 Ni -1.25 Co, 2.5 Ni -2.5 Co, 1.25 Ni -3.75 Co and 5 Co catalysts respectively.…”