Surface barriers as dominant mechanism to transport limitations in hierarchically structured catalysts – Application to the zeolite-catalyzed alkylation of benzene with ethylene

The meso-macropore network of a hierarchically structured zeolite catalyst is numerically optimized to maximize the volume-integrated reaction yield in the ethylation of benzene to produce ethylbenzene over zeolite H-ZSM-5. A hierarchical approach is used at multiple length scales to determine the optimal pore network properties. The maximum volume-integrated reaction yield of the hierarchically structured zeolite catalyst containing meso- and macropores is nearly twice the yield of a zeolite pellet containing only macropores, at the same macroporosity. To bridge the gap between modeling and experiments, a series of physical mixtures of ZSM-5 crystals and mesoporous silica, containing different weight fractions of zeolite is synthesized and used in fixed bed reactor experiments to determine the optimal pellet structure to maximize the conversion of ethylene. Comparison with reactor simulations of the zeolite composites shows that the performance of the zeolite composites might be limited by surface barriers at the external surface of the zeolite crystals, rather than by diffusion limitations within the meso-macropore network of the pellets

Identifying Performance Descriptors in CO2CO_2 Hydrogenation over Iron‐based Catalysts Promoted with Alkali Metals

Alkali metal promoters have been widely employed for preparation of heterogeneous catalysts used in many industrially important reactions. However, the fundamentals of their effects are usually difficult to access. Herein, we unravel mechanistic and kinetic aspects of the role of alkali metals in CO$_2$ hydrogenation over Fe-based catalysts through the state-of-the-art characterization techniques, spatially resolved steady-state and transient kinetic analyses. The promoters affect electronic properties of iron in iron carbides. These carbide characteristics determine catalyst ability to activate H$_2$ , CO and CO$_2$. The Allen scale electronegativity of alkali metal promoter was successfully correlated with the rates of CO$_2$ hydrogenation to higher hydrocarbons and CH$_4$ as well as with the rate constants of individual steps of CO or CO$_2$ activation . The derived knowledge can be valuable for designing and preparation of catalysts applied in other reactions where such promoters are also used

Identifying Performance Descriptors in CO2 Hydrogenation over Iron‐based Catalysts Promoted with Alkali Metals

Alkali metal promoters have been widely employed for preparation of heterogeneous catalysts used in many industrially important reactions. However, the fundamentals of their effects are usually difficult to access. Herein, we unravel mechanistic and kinetic aspects of the role of alkali metals in CO(2) hydrogenation over Fe‐based catalysts through state‐of‐the‐art characterization techniques, spatially resolved steady‐state and transient kinetic analyses. The promoters affect electronic properties of iron in iron carbides. These carbide characteristics determine catalyst ability to activate H(2), CO and CO(2). The Allen scale electronegativity of alkali metal promoter was successfully correlated with the rates of CO(2) hydrogenation to higher hydrocarbons and CH(4) as well as with the rate constants of individual steps of CO or CO(2) activation. The derived knowledge can be valuable for designing and preparing catalysts applied in other reactions where such promoters are also used

The 6th Albanian Congress of Trauma and Emergency Surgery

After a three-year quarantine from the deadliest global pandemic of the last century, ASTES is organizing to gather all health professionals in Tirana, The 6th Albanian Congress of Trauma and Emergency Surgery(ACTES 2022) on 11-12 November 2022, with the topic Trauma & Emergency Surgery and not only...with the aim of providing high quality, the best standards, and the best results, for our patients ...ACTES 2022 is the largest event that ASTES (Albanian Society for Trauma and Emergency Surgery) has organized so far with 230 presentations, and 67 foreign lecturers with enviable geography, making it the largest national and wider scientific event.The scientific program is as strong as ever, thanks to the inclusiveness, where all the participants with a mix of foreign and local lecturers, select the best of the moment in medical science, innovation, and observation.The scientific committee has selected all the presentations so that the participants of each medical discipline will have something to learn, discuss, debate, and agree with updated methods, techniques, and protocols.I hope you will join us on Friday morning, and continue the journey of our two-day event together