Effects of modifier (Gd, Sc, La) addition on the stability of low Ni content catalyst for dry reforming of model biogas

Biogas consists of a larger part of methane and a smaller part of carbon dioxide. Reforming biogas is highly desirable due to the direct conversion of the two components, yet not possible due to the current state of catalyst development. For such dry reforming of methane-rich gases (CH4/CO2 = 2) we now present catalysts with low Ni loading (2.5 wt%) modified with Gd, Sc, or La. The best catalyst reaches 49% CH4 conversion and 95% CO2 conversion at 750 degrees C. The La-modification only shows limited influence on coking and protection against catalyst deactivation although this catalyst exposed highest basicity. On the other side, Sc- and especially Gd-modified catalysts exposed stronger metal-support interaction and thus enhanced stabilization of fine Ni particles during the reaction, which is critical to preserve high performance in CH4-rich DRM. This suppressed carbon deposition and the growth of structured carbon as evidenced by STEM images and TPO of spent catalysts. In this way, exceptionally high specific H2 productivity (94 l/(gcat.h)) compared to literature was obtained on Gdmodified catalyst, and, most noteworthy, after extending the time on stream from 8 to 100 h the amount of deposited coke increased only from 3 to 4 wt%.

Automated summary

This study achieved efficient reforming of biogas using low Ni loading catalysts modified with Gd, Sc, or La. Sc and Gd modifications showed enhanced stability and resistance to coking in DRM reactions with methane-rich gases. Gd-modified catalysts demonstrated minimal increase in coke deposition even after extended operation time.