Creating New-Generation Catalysts for CO2 Hydrogenation to Methanol |
7 February 2025, Friday, 10:00am to 10:30am | Speaker: Mr. Maxim Dickieson, PhD Student, Lab of Green Catalysis at NUS |
Venue: Seminar Room 8D-1, Level 8, Temasek Laboratories | Event Organiser Host: Dr. Huang Xin |
ABSTRACT |
In efforts towards establishing a circular carbon economy, CO2 hydrogenation to methanol (CO2-to-MeOH) has received extensive interest from academia and industry. The current industrial catalyst for CO2-to-MeOH is Cu/ZnO/Al2O3; however, this system suffers from catalyst instability owing to moisture induced deactivation, hampering long-term process operation. Consequently, several Cu-free metal oxides have recently emerged as a new class of catalysts owing to the excellent selectivity and stability of these systems, among which a ZnO-ZrO2 solid solution catalyst (ZnZrOx) is undergoing pilot-scale testing. One distinct feature of ZnZrOx is its superior long-term stability, nonetheless, one downside is its lower activity compared to the industrial Cu/ZnO/Al2O3 catalyst. As such, achieving both high activity and long-term stability is a challenging mission for developing next-generation CO2-to-MeOH catalysts. Here, we introduce a strategy to promote a ZnZrOx methanol synthesis catalyst by incorporating hydrogen activation and delivery functions through optimized integration of ZnZrOx and Pd supported on carbon nanotube (Pd/CNT). The CNT in the Pd/CNT + ZnZrOx system delivers hydrogen activated on Pd to a broad area on the ZnZrOx surface, with an enhancement factor of 10 compared to the conventional Pd-promoted ZnZrOx catalyst. In CO2-to-MeOH, Pd/CNT + ZnZrOx exhibits drastically boosted activity—the highest among reported ZnZrOx-based catalysts—and excellent stability over 600 h on stream test, showing potential for practical implementation. What is more, we find that our physical mixing strategy for promoting CO2-to-MeOH catalysts is generalizable, as we present a new-age Cu-based system with state-of-the-art activity and excellent stability in preliminary long-term testing. |
ABOUT THE SPEAKER |
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Transitional Flow Regimes Driven by Shear and Buoyancy Forces |
7 February 2025, Friday, 10:30am to 11:00am | Speaker: Mr. Chan Chi Hin, PhD Student, Department of Aeronautics, Imperial College London |
Venue: Seminar Room 8D-1, Level 8, Temasek Laboratories | Event Organiser Host: Dr. Huang Xin |
ABSTRACT |
This work investigates the transitional flow regimes and their transport properties arising from the interaction between shear and buoyancy forces. While the impact of these forces has been extensively studied in isolation over the past decades - shear-driven turbulent Couette/Poiseuille/pipe flows and buoyancy-driven flows in Rayleigh-Bénard convection, their combined effects remain poorly understood. We aim to address two fundamental questions such as: 1) How does shear influence convection, and 2) can buoyancy promote transition to turbulence? To explore these questions, we consider a Rayleigh-Bénard-Poiseuille (RBP) setup, where the fluid is confined between two infinitely parallel plates, driven by a Poiseuille flow, heated from the bottom and cool from the top. The behaviour of the fluid is controlled by the Reynolds (Re) and Rayleigh (Ra) numbers, representing the relative strength of shear and buoyancy respectively. In the transitional Ra-Re parameter space considered here, the fluid exhibits five distinct flow regimes: 1) Chaotic convection, 2) stationary convection rolls, 3) wavy convection rolls, 4) intermittent convection rolls and 5) turbulence. This talk will present a detailed analysis of these flow regimes, offering insights into the interaction of shear and buoyancy forces. |
ABOUT THE SPEAKER |
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