Catalytic cascade reactions are strongly desired as a potential means of combining multistep reactions into a single catalytic reactor. Appropriate catalysts composed of multi-reactive sites to catalyze cascade reactions in a sequential fashion are central to such efforts. Here, we demonstrate a bifunctional zeolite catalyst with close proximity of Brønsted and Lewis acid sites through the synthesis of a mesoporous ZrO₂[Al]MFI nanosponge (NS). The unique mesopores of the MFI-NS allow the confinement of zirconium oxide clusters (Lewis acid sites, LA) within the few-unit-cell-thin MFI aluminosilicate zeolite wall (Brønsted acid sites, BA). Such a structure is clearly distinct from the conventional MFI zeolite, where the agglomeration of zirconium oxide clusters onto the external surface area within the crystal bulk is not possible, resulting in segregated BA and LA sites on the internal and external zeolite, respectively. By bringing the BA and LA within ZrO₂[Al]MFI-NS 30, we uncovered a more efficient catalytic route for the conversion of furfural (100% within 2 h) to γ-valerolactone (GVL) (83%). This route is only evident when the long molecular diffusion path, in the most extreme case of physically mixed ZrO₂-(LA) and Al-zeolites (BA) (45% of GVL yield), is eliminated. Unlike the bifunctional ZrO₂–Al-beta (GVL yield of 75%), where the BA concentration is greatly compromised at the expense of LA formation, we also show that the ZrO₂[Al]MFI-NS is able to maintain a high density and good stability of both types of acids.

中文翻译：

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具有可调 Lewis-Brønsted 酸位的氧化锆负载介孔 MFI 沸石的级联反应工程：以糠醛一锅法转化为 γ-戊内酯为例

强烈希望催化级联反应作为将多步反应组合到单个催化反应器中的潜在手段。由多反应位点组成的适当催化剂以连续方式催化级联反应是此类努力的核心。_{在这里，我们通过合成介孔 ZrO 2}展示了一种与布朗斯台德和路易斯酸位点非常接近的双功能沸石催化剂。[Al]MFI 纳米海绵 (NS)。MFI-NS 的独特中孔允许将氧化锆簇（路易斯酸位点，LA）限制在少数单元细胞薄的 MFI 铝硅酸盐沸石壁（布朗斯台德酸位点，BA）内。这种结构明显不同于传统的 MFI 沸石，在传统的 MFI 沸石中，氧化锆簇不可能聚集到晶体本体的外表面区域，从而导致内部和外部沸石上分别出现分离的 BA 和 LA 位点。通过将 BA 和 LA 引入 ZrO ₂ [Al]MFI-NS 30，我们发现了一种更有效的催化途径，可将糠醛（2 小时内 100%）转化为 γ-戊内酯（GVL）（83%）。这条路线只有在分子扩散路径长时才明显，在物理混合 ZrO _{2的最极端情况下}-(LA) 和铝沸石 (BA)（GVL 产率的 45%）被淘汰。与双功能 ZrO ₂ -Al-β（GVL 产率 75%）不同，其中 BA 浓度以 LA 形成为代价大大降低，我们还表明 ZrO ₂ [Al]MFI-NS 能够保持高两种酸的密度和良好的稳定性。