Heteropolyacid supported on Zr-Beta zeolite as an active catalyst for one-pot transformation of furfural to γ-valerolactone

• Published in: Applied catalysis. B, Environmental Environmental, 2019-02, Vol.241, p.588-597
• Main Authors: Winoto, Haryo Pandu, Fikri, Zuhroni Ali, Ha, Jeong-Myeong, Park, Young-Kwon, Lee, Hyunjoo, Suh, Dong Jin, Jae, Jungho
• Format: Article
• Language: English
• Subjects: Acidity; Acids; Aluminum; Ammonia; Anchoring; Bifunctional catalyst; Biomass; Catalysis; Catalysts; Chemical synthesis; Conversion; Fourier transforms; Furans; Furfural; Heteropolyacid; Hydrogen storage; Hydrogenation; Infrared spectroscopy; Ion exchange; Levulinic acid; Lewis acid; Organic chemicals; Organic chemistry; Pesticides; Propanol; Pyridines; Thermal stability; X ray photoelectron spectroscopy; Zeolites; Zirconium; Zr-Beta zeolite; γ-Valerolactone
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2018.09.031

[Display omitted] •Heteropolytungstae (HPW)-loaded Zr-Beta is synthesized via a simple post-synthesis method.•The method consists of dealumination of Al-Beta followed by sequential incorporation of Zr and HPW.•HPW/Zr-Beta zeolite possesses both isolated Lewis and Brønsted acid sites.•Transfer hydrogenation and ring-opening reactions is effectively combined using a single catalyst.•One-pot cascade conversion of furfural to GVL with a high yield (∼70%) is achieved. A novel bifunctional catalyst that enables an efficient one-pot conversion of furfural into γ-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 BrØnsted 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 BrØnsted 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 BrØnsted acidity. Especially, HPW loaded Zr-Beta demonstrated a remarkable GVL yield of ∼70% at 433 K after 24 h due to its high thermal stability and stronger BrØnsted acidity, and its activity far surpasses that of the conventional Sn-Al-Beta zeolite (∼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 BrØnsted acid sites within a single catalyst, thereby allowing the selective cascade catalysis for the cost-effective production of high-value chemicals.