No abstract

Beyond the catalytic activity of nanocatalysts, the support with architectural design and explicit boundary could also promote the overall performance through improving the diffusion process, highlighting additional support for the morphology-dependent activity. To delineate this, herein, a novel mazelike-reactor framework, namely multi-voids mesoporous silica sphere (MVmSiO 2 ), is carved through a top-down approach by endowing core-shell porosity premade Stöber SiO 2 spheres. The precisely-engineered MVmSiO 2 with peripheral one-dimensional pores in the shell and interconnecting compartmented voids in the core region is simulated to prove combined hierarchical and structural superiority over its analogous counterparts. Supported with CuZn-based alloys, mazelike MVmSiO 2 nanoreactor experimentally demonstrated its expected workability in model gas-phase CO 2 hydrogenation reaction where enhanced CO 2 activity, good methanol yield, and more importantly, a prolonged stable performance are realized. While tuning the nanoreactor composition besides morphology optimization could further increase the catalytic performance, it is accentuated that the morphological architecture of support further boosts the reaction performance apart from comprehensive compositional optimization. In addition to the found morphological restraints and size-confinement effects imposed by MVmSiO 2 , active sites of catalysts are also investigated by exploring the size difference of the confined CuZn alloy nanoparticles in CO 2 hydrogenation employing both in-situ experimental characterizations and density functional theory calculations.

Hydrogenation of CO2 to MeOH is one of the most promising technologies in mitigating the emissions of CO2 and tackling the challenge of climate change. In this work, we present a synthetic protocol for preparing a Cu–ZnO-based heterogeneous catalyst supported by siliceous nanowire networks from a single solid precursor with a tunable composition. The resulting Si–Cu–Zn catalysts were evaluated with the MeOH synthesis from the CO2 hydrogenation reaction operated at moderate conditions (30 barg and 200–280 °C). A specific MeOH yield of 402 mgMeOH·gCu –1·h–1 and a MeOH selectivity of 51% were obtained at 240 °C. Such a performance was attributed to several structural and compositional merits, granted through the attentively engineered synthetic procedures. Small Cu nanoparticle (NP) size was achieved and maintained by the high dispersion of Cu to the atomic level in the precatalyst and the incorporation of ZnO as a structural promoter. Moreover, the desirable Cu–ZnO synergistic effect can be further attained from the strong metal–support interaction (SMSI) between the Cu NPs and the partially reduced ZnO phase. Lastly, the robust siliceous nanowire networks provided decent spatial confinement to contain the growth of Cu NPs while offering high accessibility with the macroscopic porous morphology. The catalyst exhibited stable performance over a week’s long stability test while keeping its structural integrity intact. Overall, this study may offer an alternative design and synthesis strategy for the well-received Cu–ZnO system to approach its high performance in CO2 hydrogenation.