Vu Hue-Tong, Goepel Michael, Gläser Roger
Institute of Chemical Technology, Universität Leipzig Linnéstr. 3 04103 Leipzig Germany
RSC Adv. 2021 Jan 29;11(10):5568-5579. doi: 10.1039/d0ra08907a. eCollection 2021 Jan 28.
La cation exchange is shown to improve the hydrothermal stability and catalytic activity of bifunctional zeolite Pt/Y catalysts in the aqueous-phase hydrogenation of levulinic acid (LA) with formic acid (FA) as hydrogen source. La cation exchange of zeolite Y ( / = 16) was conducted both in aqueous solution and in the solid state. The hydrothermal stability of La-containing zeolite Y probed by exposure to the reaction mixture (0.2 mol L LA, 0.6 mol L FA) at 473 K under autogenous pressure for 24 h improves with increasing La content. The material exhibiting the highest La content (0.5 mmol g) is the most stable with a preservation of 25% of the initial specific micropore volume after the hydrothermal treatment, whereas unmodified zeolite Y completely loses its microporosity. A new procedure using DRIFTS is a useful supplementary tool for quantifying the framework degradation of Y-type zeolites after hydrothermal treatment. Bifunctional Pt/Y catalysts after La cation exchange are more active than the parent Y-zeolite for the hydrogenation of LA to γ-valerolactone (GVL), with significant enhancements in LA conversion, , 94% 42%, and GVL yield, , 72% 34%., after 24 h.
结果表明，阳离子交换可提高双功能沸石Pt/Y催化剂在以甲酸（FA）为氢源的水相加氢反应中对乙酰丙酸（LA）的水热稳定性和催化活性。Y型沸石（Si/Al = 16）的La阳离子交换在水溶液和固态中均进行。通过在473 K的自生压力下将含La的Y型沸石暴露于反应混合物（0.2 mol L LA，0.6 mol L FA）中24 h来探测其水热稳定性，结果表明其随La含量的增加而提高。La含量最高（0.5 mmol g）的材料最稳定，水热处理后保留了25%的初始比微孔体积，而未改性的Y型沸石则完全失去了其微孔性。一种使用漫反射红外傅里叶变换光谱（DRIFTS）的新方法是定量水热处理后Y型沸石骨架降解的有用补充工具。La阳离子交换后的双功能Pt/Y催化剂在将LA加氢生成γ-戊内酯（GVL）方面比母体Y型沸石更具活性，24 h后LA转化率显著提高，从42%提高到94%，GVL产率从34%提高到72%。
