Dry reforming of methane (DRM) converts CH 4 and CO 2 into syngas, but Ni catalysts are limited by inefficient active site utilization and deactivation. Ni/ZrO 2 catalysts with bulk Ni loadings of 0.89, 2.78, 4.92, and 9.66 wt%, as determined by ICP-OES, were prepared by impregnation to clarify how Ni loading affects structure, reducibility, catalytic performance, and deactivation. Increasing Ni loading enlarged the NiO crystallite size from 5.2 to 30.4 nm and the metallic Ni crystallite size from 8.6 to 28.2 nm, while decreasing Ni dispersion from 10.4% to 4.1%. Although total H 2 consumption increased from 15.2 to 121.1 mmol·g − 1 , the reduction degree decreased from 100% to 74%, indicating that higher Ni content did not proportionally increase accessible metallic Ni sites. The 10NZ catalyst exhibited the highest initial CH 4 and CO 2 conversions but underwent the most severe deactivation. By contrast, 5NZ provided the best balance between apparent activity and stability under the tested conditions. Postreaction characterization showed that Ni crystallite growth and carbon deposition became more pronounced at high Ni loading. These results demonstrate that DRM performance depends on balancing total Ni content, active site utilization, and resistance to deactivation.
Yang et al. (Wed,) studied this question.