Pusan National University

About: Pusan National University is a education organization based out in Busan, South Korea. It is known for research contribution in the topics: Population & Catalysis. The organization has 24124 authors who have published 45054 publications receiving 819356 citations. The organization is also known as: Busan National University & Pusan University.

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

Abstract: 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 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 ∼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 (∼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

Digital transformation and the new logics of business process management

Abstract: Business process management (BPM) research emphasises three important logics – modelling (process), infrastructural alignment (infrastructure) and procedural actor (agency) logics. These logics cap...

Cosmological Shock Waves in the Large Scale Structure of the Universe: Non-gravitational Effects

Abstract: Cosmological shock waves result from supersonic flow motions induced by hierarchical clustering of nonlinear structures in the universe. These shocks govern the nature of cosmic plasma through thermalization of gas and acceleration of nonthermal, cosmic-ray (CR) particles. We study the statistics and energetics of shocks formed in cosmological simulations of a concordance $\Lambda$CDM universe, with a special emphasis on the effects of non-gravitational processes such as radiative cooling, photoionization/heating, and galactic superwind feedbacks. Adopting an improved model for gas thermalization and CR acceleration efficiencies based on nonlinear diffusive shock acceleration calculations, we then estimate the gas thermal energy and the CR energy dissipated at shocks through the history of the universe. Since shocks can serve as sites for generation of vorticity, we also examine the vorticity that should have been generated mostly at curved shocks in cosmological simulations. We find that the dynamics and energetics of shocks are governed primarily by the gravity of matter, so other non-gravitational processes do not affect significantly the global energy dissipation and vorticity generation at cosmological shocks. Our results reinforce scenarios in which the intracluster medium and warm-hot intergalactic medium contain energetically significant populations of nonthermal particles and turbulent flow motions.