Novel SSZ-39 zeolite-based Ru catalysts were synthesized by impregnation on as-synthesized metallic and protonated SSZ-39 and a one-pot synthesis strategy. The study focused on the influence of the SSZ-39 zeolite characteristics and catalyst preparation method type toward levulinic acid (LA) selective conversion to γ-valerolactone (GVL) under relatively mild reaction conditions (150 °C, 4 h and 2 MPa of H with HO and THF as solvents). Catalysts exhibited excellent catalytic efficiency (100 % LA conversion and 98.3 % GVL selectivity) and remarkable hydrothermal stability. The results revealed a correlation between excellent catalytic activity and the structural features of the synthesized catalysts, predominantly dependent on their appropriate surface acidity (strong Lewis acid sites) and enhanced electronic interaction between Ru species and SSZ-39. The one-pot method promoted the formation of mesopores besides the zeolitic micropores present in SSZ-39; therefore, the catalyst prepared by the one-pot method (Ru/SSZ-39) showed purer SSZ-39 crystallites and a slightly larger catalytic surface area of 439 m/g than the original zeolite surface area of 424 m/g. In addition, the original zeolite crystals retained their morphology as spherical aggregates and remained unaffected by Ru impregnation on the metallic or protonated support during the synthesis of Ru/Na-SSZ-39 and Ru/H-SSZ-39 catalysts, respectively. Notably, it has been demonstrated that SSZ-39 zeolite effectively acts as a support for the preparation of Ru catalyst in biomass conversion reactions. Moreover, the reused catalyst exhibited consistent activity over six cycles, maintaining its structural framework without significant loss in activity.

中文翻译：

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SSZ-39 沸石基 Ru 催化剂用于乙酰丙酸选择性加氢制备 γ-戊内酯：合成方法和沸石酸度的影响

通过浸渍合成的金属质子化 SSZ-39 和一锅法合成策略合成了新型 SSZ-39 沸石基 Ru 催化剂。研究重点是SSZ-39沸石特性和催化剂制备方法类型对在相对温和的反应条件（150℃、4小时和2MPa的H2条件下）乙酰丙酸（LA）选择性转化为γ-戊内酯（GVL）的影响。以 H2O 和 THF 为溶剂）。催化剂表现出优异的催化效率（100% LA 转化率和 98.3% GVL 选择性）和卓越的水热稳定性。结果揭示了优异的催化活性与合成催化剂的结构特征之间的相关性，主要取决于其适当的表面酸度（强路易斯酸位点）以及Ru物质和SSZ-39之间增强的电子相互作用。一锅法促进了SSZ-39中除沸石微孔之外的中孔的形成；因此，通过一锅法制备的催化剂(Ru/SSZ-39)表现出更纯的SSZ-39微晶和比原始沸石表面积424 m/g稍大的催化表面积439 m/g。此外，在Ru/Na-SSZ-39和Ru/H-SSZ-39催化剂的合成过程中，原始沸石晶体保留了球形聚集体的形态，并且不受金属或质子化载体上Ru浸渍的影响。值得注意的是，已经证明SSZ-39沸石可以有效地作为生物质转化反应中Ru催化剂制备的载体。此外，重复使用的催化剂在六个循环中表现出一致的活性，保持其结构框架而没有显着的活性损失。