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Fabrication of sintering- and carbon-free Ni catalysts for methane dry reforming (MDR), which is attractive to upgrade greenhouse gases CH 4 and CO 2 , is challenging. In this work, we innovatively synthesized Ni-Cu alloy nanoparticles confined by physical encapsulation and chemical metal-support interaction (MSI); the synergism of alloy effect, size effect, MSI, and confinement effect in the catalysts gave high rates of CH 4 and CO 2 of 6.98 and 7.16 mmol/(g Ni s), respectively, at 1023 K for 50 h. The rates were 2-3 times enhanced compared to those in the literature. XRD, TEM, H 2 -TPR, and so forth revealed that the alloy effect, size effect, and MSI of Ni-Cu and CeO 2 enhanced the MDR activity; MSI promoted the ceria surface lattice oxygen mobility and generated more oxygen vacancies, almost completely gasifying carbon deposits; chemical confinement from MSI and physical confinement from SiO 2 nanospheres realized sintering-free alloys and CeO 2 nanoparticles. The synergistic approach provides a universal strategy for sintering- and carbon-free Ni catalyst design for MDR reaction.

In this work, we studied CO 2 reforming with the methane (CRM) reaction over Ni-Cu alloy nanoparticles encapsulated in SiO 2 nanospheres, for which combinational functions of alloy effect, size effect, metal-support interaction, and confinement effect exhibited high performance, good sintering resistance, and trace carbon deposition in CRM. The appropriate Cu-addition catalysts 0.2Cu-Ni@SiO 2 and 0.5Cu-Ni@SiO 2 had smaller NiCu alloy nanoparticles and a stronger metal-support interaction, exhibiting a better performance than the excessive Cu-addition catalysts 1.5Cu-Ni@SiO 2 and 3Cu-Ni@SiO 2 having Cu clusters and a weaker metal-support interaction. The best synergy of alloy effect, size effect, confinement effect, and metal-support interaction in the 0.5Cu-Ni@SiO 2 catalyst contributed to the highest rates of CH 4 and CO 2 in CRM reported so far. This work demonstrates the importance of appropriate Cu addition in Ni-Cu@SiO 2 catalysts, and the synergy for perfectly resolving sintering and carbon deposition in CRM.

Developing high performance catalysts for the low temperature CO 2 reforming with methane (CRM) reaction is a challenge due to the occurrences of metal sintering and carbon deposition. In this study, we synthesized CeO 2 modified Ni@SiO 2 catalysts with excellent properties of sintering-resistance and low carbon deposition for high performance low temperature CRM. The Ni@SiO 2 -CeO 2 catalysts displayed a size effect from tiny Ni nanoparticles to enhance CRM performance and a confinement effect from silica encapsulation to limit Ni sintering and exhibited oxygen storage capacity from ceria to reduce carbon deposition. Performance and characterization results revealed that the Ni@SiO 2 -CeO 2 -W catalyst with smaller ceria size exhibited higher performance and lower carbon deposition than the Ni@SiO 2 -CeO 2 -E catalyst with bigger ceria size, because the smaller ceria nanoparticles activated more CO 2 . This work provided a simple strategy to deposit small sized ceria on the Ni@SiO 2 catalyst surface for the performance enhancement of low temperature CRM.