Production of syngas by methane dry reforming over the catalyst ZNi_1‐xCe_x: effects of catalyst calcination and reduction temperature

Abstract

BACKGROUND: A 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.RESULTS: A series of catalysts, Ni 1-x Ce x , 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 CH 4 and CO 2 percent conversion. The catalyst 40Ni 0.75 Ce 0 . 25 /Al 2 O 3 calcined at 700 °C possessed a high conversion of CO 2 and CH 4 . The reduced catalyst (40Ni 0.75 Ce 0.25 /Al 2 O 3 ) 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 (% CO 2 Conversion dropped: 100% to 94%) than for the calcined catalyst (% CO 2 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).CONCLUSION: The calcined catalyst, 40Ni 0.75 Ce 0.25 /Al 2 O 3 -700 °C, was very active with high methane (91%) and CO 2 (94%) conversions; also, the reduced catalyst was active and possessed high methane (88%) and CO 2 (100%) conversions at low reaction temperatures. Overall, the calcined catalyst was comparatively more stable than the reduced catalyst.

Dry reforming of HCs (methane, ethane, and propane) over a 40Ni0.75(Ce1−xFex)0.25/Al2O3 catalyst: a comparative study

“…The phase serves to inhibit the adherence of coke to the catalyst surface, thereby preventing undesirable coke deposition during the catalytic process. 30 Ceria's oxygen storage capacity enhances CO 2 adsorption on the catalyst, resulting in higher conversion compared to hydrocarbons (HCs). 31 Compared to FeCe 2 O 4 , the NiO–CeO 2 catalyst exhibits significantly improved catalytic activity, excellent stability, and reduces the coke formation.…”