In situ confinement of ultrasmall Cu nanoparticles within silicalite-1 zeolite for catalytic reforming of methanol to hydrogen

As non-noble metal catalyst, Cu-based catalyst shows promising applying potential in the aqueous-phase reforming of methanol (APRM) due to its high dehydrogenation activity and low CO selectivity, but the poor thermal and hydrothermal stability. Herein, a Cu@S-1 catalyst with ultrasmall-2nm Cu nanoparticles size was synthesized for the first time using one-step in-situ encapsulation strategy. By the confinement effect of the zeolite Silicalite-1 (S-1) micropores, the 1 wt%Cu@S-1 catalyst exhibited absolutely superior thermal stability without using any other promoter, as well as relatively good hydrothermal stability. After 600–700 °C high-temperature treatment, no obvious aggregation of the Cu nanoparticles was found, and superior performance in the steam reforming of methanol (SRM) was maintained after running for 36 h at 300 °C. In the APRM at 210 °C, the 1 wt%Cu@S-1 catalyst showed six-fold higher hydrogen releasing rate (4.26 × 105 μmolH2·gCu−1·h−1) than the impregnated 1 wt%Cu/S-1-im catalyst, meanwhile it exhibited even better performance than the commercial 5%Pd/C catalyst. Compared with the impregnated 1 wt%Cu/S-1-im catalyst, the confinement effect of the internal pores of the S-1 for the Cu nanoparticles in the 1 wt%Cu@S-1 catalyst effectively inhibited aggregation of the Cu particles and Cu leaching in APRM, thus greatly improved the activity and hydrothermal stability.