High selective hydrogenolysis of furfural to 2-methylfuran over a metal oxide-based catalyst is promising and challenging. In this paper, a Zr-modified CoO x (Zr 1 Co 6 -325) catalyst was prepared via a simple co-precipitation/reduction and exhibited superior initial activity and remarkable circular stability during the hydrogenolysis of furfural (FUR) to 2-methylfuran (2-MF). As high as 71.2 % yield of 2-MF was achieved at 170 °C for 2 h and nearly no deactivation was found after five cycles, much better than those of reduced Co 3 O 4 catalyst (Co 3 O 4 -250). Comprehensive studies demonstrated that the over-reduction of the CoO species during the reaction process was the main cause of catalyst deactivation. The introduction of Zr species, on the one hand, inhibited the over-reduction of CoO species during reaction processes, thereby enhancing the circular stability. On the other hand, the introduction of Zr species promoted the activation and dissociation of H 2 and therefore improved the activity. This research unveiled the stabilizing effect of Zr species on CoO, providing guidance for the design of high-stable CoO-based catalysts.
To introduce a hierarchical porous structure into SAPO-34 zeolites and adjust their acid properties and crystalline size, a series of Zr-modified SAPO-34 zeolites (Zrx-SAPO-34 (x = 0.25, 0.50 and 0.75)) with hierarchical porous structure were synthesized by hydrothermal crystallization using palygorskite as a silicon and partial aluminum source, morpholine and tetraethylammonium hydroxide as organic structure directing agents and UiO-66 as a co-template agent. The obtained catalysts were characterized via XRD, SEM, TEM, EDX, N2-adsorption–desorption, NH3-TPD, FTIR, Py-IR, XRF, 29Si MAS NMR and TG analyses. The catalytic performance of Zrx-SAPO-34 in the methanol-to-olefin (MTO) transformation was investigated in a fixed bed reactor. The introduction of a hierarchical porous structure effectively enhanced the diffusion and mass transfer of the reactants/products, prolonging the catalytic lifetime. Additionally, the optimization of the acidity dramatically improved the selectivity for light olefins. Under the reaction conditions wherein the reaction temperature was 400 °C, the feed of WHSV was 2.0 h−1, the mass of the catalyst was 0.5 g and at atmospheric pressure, the Zr0.50-SAPO-34 zeolites exhibited optimum catalytic performance, where the methanol conversion was 100%, the light olefin selectivity was 98.66% and the catalytic lifetime was more than 1500 min.
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