Knowledge and social capacity building for sustainable urban transformation

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Propylene/Nitrogen Separation in a By-Stream of the Polypropylene Production: From Pilot Test and Model Validation to Industrial Scale Process Design and Optimization

Two industrial-scale pressure swing adsorption (PSA) processes were designed and optimized by simulations: recovery of only nitrogen and recovery of both nitrogen and propylene from a polypropylene manufacture purge gas stream. MIL-100­(Fe) granulates were used as adsorbent. The mathematical model employed in the simulations was verified by a PSA experiment. The effect of several operating parameters on the performance of the proposed PSA processes was investigated. For the nitrogen recovery, a 5-step 2-column PSA process produced a nitrogen stream of 95.4% purity with recovery of 85.2%, productivity of 6.0 mol N₂/kg adsorbent/h, and power consumption of 156 Wh/kgN₂. Nitrogen and propylene with 96.2% and 97.6% purity, respectively, were obtained from the 6-step 3-column nitrogen and propylene recovery PSA process. The nitrogen and propylene recoveries obtained are 98.4% and 91.0%, respectively. The nitrogen and propylene productivities were estimated as 4.61 and 1.83 mol product/kg adsorbent/h and the power consumption as 383 Wh/kgN₂

Syngas Purification by Porous Amino-Functionalized Titanium Terephthalate MIL-125

The adsorption equilibrium of carbon dioxide (CO₂), carbon monoxide (CO), nitrogen (N₂), methane (CH₄), and hydrogen (H₂) was studied at 303, 323, and 343 K and pressures up to 7 bar in titanium-based metal–organic framework (MOF) granulates, amino-functionalized titanium terephthalate MIL-125­(Ti)_NH₂. The affinity of the different adsorbates toward the adsorbent presented the following order: CO₂ > CH₄ > CO > N₂ > H₂, from the most adsorbed to the least adsorbed component. Subsequently, adsorption kinetics and multicomponent adsorption equilibrium were studied by means of single, binary, and ternary breakthrough curves at 323 K and 4.5 bar with different feed mixtures. Both studies are complementary and aim the syngas purification for two different applications, hydrogen production and H₂/CO composition adjustment, to be used as feed in the Fischer–Tropsch processes. The isosteric heats were calculated from the adsorption equilibrium isotherms and are 21.9 kJ mol^–1 for CO₂, 14.6 kJ mol^–1 for CH₄, 13.4 kJ mol^–1 for CO, and 11.7 kJ mol^–1 for N₂. In the overall pressure and temperature range, the adsorption equilibrium isotherms were well-regressed against the Langmuir model. The multicomponent breakthrough experimental results allowed for validation of the adsorption equilibrium predicted by the multicomponent extension of the Langmuir isotherm and validation of the fixed-bed mathematical model. To conclude, two pressure swing adsorption (PSA) cycles were designed and performed experimentally, one for hydrogen purification from a 30/70% CO₂/H₂ mixture (hydrogen purity was 100% with a recovery of 23.5%) and a second PSA cycle to obtain a light product with a H₂/CO ratio between 2.2 and 2.4 to feed to Fischer–Tropsch processes. The experimental cycle produced a light stream with a H₂/CO ratio of 2.3 and a CO₂-enriched stream with 86.6% purity as a heavy product. The CO₂ recovery was 93.5%

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18-49, 50-69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population.The aim of this study was to inform vaccination prioritization by modelling the impact of vaccination on elective inpatient surgery. The study found that patients aged at least 70 years needing elective surgery should be prioritized alongside other high-risk groups during early vaccination programmes. Once vaccines are rolled out to younger populations, prioritizing surgical patients is advantageous