چكيده به لاتين
One of the efficient methods for syngas production is the tri-reforming of methane process, which is recognized as an environmentally friendly technology due to its utilization of two greenhouse gases, methane and carbon dioxide. In this process, nickel-based catalysts are widely used.
In this study, mesoporous activated carbon with a high specific surface area (673 m²/g) was employed as the catalyst support. To enhance its structural properties, surface modification with HNO₃ was performed. Nickel catalysts with different weight percentages (7.5%, 10%, and 12.5%) were synthesized using the wet impregnation method on modified activated carbon. The effect of nickel content and calcination temperature on the structural characteristics and catalytic performance was investigated separately. The catalysts were analyzed using H₂-TPR, XRD, and BET techniques.
The results showed that all catalysts had high specific surface areas (521.51 to 599.64 m²/g), mesoporous structures, and pore size distributions ranging from 2.17 to 2.35 nm. Reactor experiments indicated that increasing the nickel content from 5% to 10% improved the catalytic efficiency. The 10%Ni/AC catalyst exhibited superior performance at 750°C, achieving 87.2% methane conversion and 80.3% carbon dioxide conversion with a feed composition of CH₄:CO₂:H₂O:O₂ = 1:0.75:0.75:0.2:0.4. After 5 hours of reaction, the methane conversion loss was only 3.0%.
In the second part of the study, the effect of metal oxides (SrO, La₂O₃, MgO, and ZrO₂) as promoters alongside activated carbon was investigated. Among these promoters, the ZrO₂-containing catalyst exhibited the best performance. Additionally, increasing the Zirconium oxide (ZrO₂) content up to 7 wt% led to a 7% increase in methane conversion at 750°C. Under the same conditions (CH₄:CO₂:H₂O:O₂ = 1:0.75:0.75:0.2:0.4), methane and carbon dioxide conversions reached 92.2% and 80.3%, respectively, while the catalyst demonstrated high thermal stability, with only 0.5% loss in methane conversion.
In both sections of the study, the effects of feed ratio, reduction temperature, and GHSV on catalyst performance were evaluated. Furthermore, the calcination temperature was independently analyzed concerning the structural properties and catalytic activity of the catalysts.
