Heteropolyacid supported on Zr-Beta zeolite as an active catalyst for one-pot transformation of furfural to γ-valerolactone
Heteropolyacid supported on Zr-Beta zeolite as an active catalyst for one-pot transformation of furfural to γ-valerolactone
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DOI：
10.1016/j.apcatb.2018.09.031
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发表时间：
2019-02-01
影响因子：
22.1
通讯作者：
Jae, Jungho
中科院分区：
文献类型：
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作者：
Winoto, Haryo Pandu;Fikri, Zuhroni Ali;Jae, Jungho
通过在Zr-Beta沸石上锚定杂多酸（HPA），研制了一种新型双功能催化剂，使糠醛一锅高效转化为γ -戊内酯（GVL）。催化剂由al - β脱铝、通过固态离子交换将Zr掺入β骨架、HPA浸渍等后合成工艺制备。以zr - β为路易斯酸催化剂，以2-丙醇为供氢体，催化糠醛和乙酰丙酸/酯的转移加氢反应。为了解决zr - β不能催化呋喃水解开环生成GVL的问题，在zr - β上引入磷钨酸（HPW）和硅钨酸（HSiW）作为Bronsted酸位。利用XRD、UV-vis、XPS、氨的TPD和吸附吡啶的FT-IR光谱对催化剂进行表征，表明HPA/Zr-Beta具有分离的Lewis和Bronsted酸位点。当它们用于一锅级联转化糠醛时，HPA/Zr-Beta对GVL的初始活性是Zr-Beta的2-3倍，这是由于添加的Bronsted酸度促进了呋喃水解开环的增强。特别是，由于高热稳定性和较强的Bronsted酸性，负载HPW的Zr-Beta沸石在433 K后24 h的GVL产率达到了70%左右，其活性远远超过了传统的Sn-Al-Beta沸石（40%左右）。总的来说，本研究表明，将HPA掺入Lewis酸Sn-或Zr-Beta沸石中是一种有效的策略，可以在单一催化剂中产生分离的Lewis和Bronsted酸位点，从而实现选择性级联催化，从而经济高效地生产高价值化学品。
A novel bifunctional catalyst that enables an efficient one-pot conversion of furfural into gamma-valerolactone (GVL) has been developed by anchoring heteropolyacid (HPA) on Zr-Beta zeolite. The catalysts were prepared by a post-synthesis procedure, which consists of the dealumination of Al-Beta, incorporation of Zr into the beta framework through solid-state ion-exchange and impregnation of the HPA. Zr-Beta is used as a Lewis acid catalyst to catalyze the transfer hydrogenation of furfural and levulinic acid/ester using 2-propanol as a hydrogen donor. To deal with the inability of Zr-Beta to catalyze the hydrolytic ring-opening of furans toward GVL, phosphotungstic acid (HPW) and silicotungstic acid (HSiW) were introduced to the Zr-Beta as Bronsted acid sites. The characterization of the catalysts using XRD, UV-vis and XPS as well as TPD of ammonia and FT-IR spectroscopy of the adsorbed pyridine revealed that the HPA/Zr-Beta possesses both isolated Lewis and Bronsted acid sites. When they were applied to the one-pot cascade conversion of furfural, the initial activity of the HPA/Zr-Beta toward GVL production were 2-3 times greater than that for Zr-Beta due to the enhanced hydrolytic ring-opening of the furans promoted by the added Bronsted acidity. Especially, HPW loaded Zr-Beta demonstrated a remarkable GVL yield of similar to 70% at 433 K after 24 h due to its high thermal stability and stronger Bronsted acidity, and its activity far surpasses that of the conventional Sn-Al-Beta zeolite (similar to 40%). Overall, this study demonstrates that an incorporation of HPA into Lewis acid Sn- or Zr-Beta zeolites is an effective strategy to create isolated Lewis and Bronsted acid sites within a single catalyst, thereby allowing the selective cascade catalysis for the cost-effective production of high-value chemicals.