Influence of post-synthetic modifications on the composition, acidity and textural properties of ZSM-22 zeolite

[EN] In this work, an extensive investigation of the preparation of a large body of desilicated ZSM-22 zeolites and their basic characterization is presented. We investigate the effects of the properties of the starting zeolite, and we employ mixtures of NaOH with CTAB or TBAOH as well as subsequent acid washings to create mesoporous zeolites. Scanning and transmission electron microscopy and nitrogen adsorption revealed that the cristal morphology of the starting zeolite appears to be the dominant parameter which influences the mesopore generation. Mesopores were effectively created within the rod-like commercial crystallites, whereas the thinner dimensions of the needle-shaped particles of the lab-made zeolite represent an obstacle for an intra-mesopore creation. The alkaline, surfactant-assisted or combined NaOH/TBAOH desilication methods resulted in mesopores with different shape and size from the commercial zeolite. The sequential acid washing generally resulted in increased micropore volume with respect to the desilicated samples. Elemental analysis showed that extra-framework Al species were generated upon the desilication treatments, which are eventually removed by the acid treatment. The acidity studied by FTIR demonstrated that this occurs without a marked modification of the Brønsted acidity, whereas the concentration of surface silanol hydroxyl groups is increased. The comparison between the total Al concentration and the amount of Al in acidic sites quantified by pyridine adsorption shows that the acidity was recovered after the acid washing and suggests that original non-acidic Al species in the starting materials may have a role in the formation of both Lewis and extra-framework species upon desilication.This publication is a part of the inGAP Centre of research-based Innovation, which receives financial support from the Norwegian Research Council under contract no. 174893. F.R and M.T.N thank to MINECO for financial support through projects MAT2015-71842-P and SEV-2012-0267. All the authors thank the Electron Microscopy Service of the Universitat Politecnica de Valencia.Del Campo Huertas, P.; Beato, P.; Rey Garcia, F.; Navarro, MT.; Olsbye, U.; Lillerud, K.; Svelle, S. (2018). Influence of post-synthetic modifications on the composition, acidity and textural properties of ZSM-22 zeolite. Catalysis Today. 299:120-134. https://doi.org/10.1016/j.cattod.2017.04.042S12013429

Propene Production by Butene Cracking. Descriptors for Zeolite Catalysts

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Catalysis, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acscatal.0c02799[EN] Among the possible on-purpose technologies for propene production, direct conversion of butene-rich fractions to propene represents an attractive alternative to conventional routes such as steam cracking or fluid catalytic cracking. Here, we present an approach for designing an efficient ZSM-5-based catalyst for the selective cracking of butenes to propene by properly balancing diffusional and compositional effects. Instead of the large coffin-shaped ZSM-5 crystallites with very high Si/Al ratios generally reported, the optimal catalyst in terms of propene selectivity and catalyst life was found to be a ZSM-5 zeolite with a squared morphology, submicron-sized crystals (0.8 x 0.3 x 1.0 mu m), and a Si/Al molar ratio of around 300. For this crystal conformation, the short dimensions of both sinusoidal and straight channels facilitate propene diffusion and reduce its consumption in consecutive reactions, limiting the formation of C5+ oligomers and aromatics and maximizing propene selectivity. Coffin-type ZSM-5 crystals, with higher diffusional restrictions than square-shaped crystals, show faster catalyst deactivation than the latter, independently of the crystal size and Al content. However, among the ZSM-5 zeolite crystallites with a coffin morphology, the one presenting intergrowths on the (010) face, with a larger proportion of sinusoidal channels, shows a lower aromatic selectivity and deactivation rate, whereas the other two, with straight channels open to the clean (010) faces, favor the formation of aromatics by direct cyclization-dehydrogenation of oligomeric intermediates.This work has been supported by Saudi Aramco, by the Spanish Government-MICINN through "Severo Ochoa" (SEV-2016-0683) and RTI2018-101033-B-I00, and by Generalitat Valenciana (AICO/2019/060). We thank the Electron Microscopy Service of the UPV for their help in sample characterization.Del Campo Huertas, P.; Navarro Villalba, MT.; Shaikh, SK.; Khokhar, MD.; Aljumah, F.; Martínez, C.; Corma Canós, A. (2020). Propene Production by Butene Cracking. Descriptors for Zeolite Catalysts. ACS Catalysis. 10(20):11878-11891. https://doi.org/10.1021/acscatal.0c02799S11878118911020Agency, I. E. 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Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study

PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Improvement of the methanol-to-hydrocarbons catalytic performance for one-dimensional zeolites obtained by post-synthetic modifications

The relatively short lifetime of unidimensional 10-ring zeolite catalysts in the methanol to hydrocarbons reaction is improved by a factor of ~20 by introducing mesoporosity in the zeolites via sequential desilication and acid post-synthetic treatments. The catalytic selective production of high quality low-aromatics gasoline precursors is improved. By using two morphologically distinct starting ZSM-22 samples and three desilication methods, the study concludes that the conditions of the treatment need to be adjusted depending on the properties of the starting material in order to produce more efficient MTH catalysts. Particularly, the parent zeolite morphology is the most influential parameter for the mesopore generation. The influence of the starting material on the change in the catalyst properties (composition, acidity, porosity) is also reflected in the catalytic improvement, which is explained based on a more efficient use of the hierarchical catalyst crystal, allowing longer operation of the alkene cycle during MTH. Operando XRD experiments provided insights into the ZSM-22 deactivation mechanism as a function of the applied post-synthetic method and co-feeding experiments

Planta de obtención de biodiesel y biogasolina a partir de aceites vegetales con capacidad de 50.000 ton-año en Castellón

Consulta en la Biblioteca ETSI Industriales (8929)[ES] Hoy en día, debido al agotamiento de las fuentes combustibles derivadas del petróleo (se estima en 50 años las reservas probadas de petróleo mundial), la humanidad es cada vez más consciente de que las fuentes de energía alternativa, como los biocombustibles, son cada vez más importantes. Por otra parte, las preocupaciones sobre el calentamiento global causado por las emisiones de gases del efecto invernadero de fuentes de energía fósiles, están aumentando el interés en esta energía sostenible que pueda sustituir a los combustibles fósiles. Se ha comenzado a implementar nuevas medidas para disminuir las notorias emisiones de gases contaminantes, siendo una alternativa en desarrollo el biodiésel obtenido por craqueo catalítico de aceites vegetales. Este tipo de combustible puede ser empleado sin mayores modificaciones en motores diesel y posee gran cantidad de ventajas frente a éste último. Es por esto por lo que se trata de continuar con el desarrollo e investigación de la tecnología FCC, principalmente a nivel europeo en países como Austria y Alemania. El producto obtenido de FCC formará parte en un porcentaje en mezcla con productos de refinería. En el presente proyecto se diseña una planta de obtención de biocombustibles a partir de aceites vegetales y aceites vegetales usados, cuyas características no son aptas para el consumo humano, mediante el proceso de craqueo catalítico fluidizado FCC. La planta es anexa a la BP Oil España Refinería de Castellón S.A.U., de la que se reciben algunos servicios necesarios para la misma El FCC es un proceso de conversión empleado en refinerías de petróleo. La aplicación de esta tecnología permite obtener una gasolina de alta calidad a partir de fuentes renovables, así como subproductos útiles. En la realización del proyecto se describen el proceso y el equipo necesario para la planta FCC. Se tienen en cuenta los factores más importantes de dicha tecnología, tales como la caracterización y calidad del producto obtenido, y los costes involucrados en el proceso y la construcción de la planta, así como el estudio de seguridad y salud. Además, se enfatiza en los aspectos medioambientales que involucran la producción de biocombustibles, como las emisiones de N2O y NOx por parte de fertilizantes, la influencia en la biodiversidad, fuentes del suelo y seguridad alimentaria.Campo Huertas, PD. (2012). Planta de obtención de biodiesel y biogasolina a partir de aceites vegetales con capacidad de 50.000 ton-año en Castellón. http://hdl.handle.net/10251/29126

Activation and conversion of alkanes in the confined space of zeolite-type materials

[EN] Microporous zeolite-type materials, with crystalline porous structures formed by well-defined channels and cages of molecular dimensions, have been widely employed as heterogeneous catalysts since the early 1960s, due to their wide variety of framework topologies, compositional flexibility and hydrothermal stability. The possible selection of the microporous structure and of the elements located in framework and extraframework positions enables the design of highly selective catalysts with well-defined active sites of acidic, basic or redox character, opening the path to their application in a wide range of catalytic processes. This versatility and high catalytic efficiency is the key factor enabling their use in the activation and conversion of different alkanes, ranging from methane to long chain n-paraffins. Alkanes are highly stable molecules, but their abundance and low cost have been two main driving forces for the development of processes directed to their upgrading over the last 50 years. However, the availability of advanced characterization tools combined with molecular modelling has enabled a more fundamental approach to the activation and conversion of alkanes, with most of the recent research being focused on the functionalization of methane and light alkanes, where their selective transformation at reasonable conversions remains, even nowadays, an important challenge. In this review, we will cover the use of microporous zeolite-type materials as components of mono- and bifunctional catalysts in the catalytic activation and conversion of C-1(+) alkanes under non-oxidative or oxidative conditions. In each case, the alkane activation will be approached from a fundamental perspective, with the aim of understanding, at the molecular level, the role of the active sites involved in the activation and transformation of the different molecules and the contribution of shape-selective or confinement effects imposed by the microporous structure.This work has been supported by the Spanish Government-MICINN through "Severo Ochoa" (SEV-2016-0683) and RTI2018-101033-B-I00, and by Generalitat Valenciana (AICO/2019/060).Del Campo Huertas, P.; Martínez, C.; Corma Canós, A. (2021). Activation and conversion of alkanes in the confined space of zeolite-type materials. Chemical Society Reviews. 50(15):8511-8595. https://doi.org/10.1039/d0cs01459aS85118595501

Preoperative nasopharyngeal swab testing and postoperative pulmonary complications in patients undergoing elective surgery during the SARS-CoV-2 pandemic.

BACKGROUND: Surgical services are preparing to scale up in areas affected by COVID-19. This study aimed to evaluate the association between preoperative SARS-CoV-2 testing and postoperative pulmonary complications in patients undergoing elective cancer surgery. METHODS: This international cohort study included adult patients undergoing elective surgery for cancer in areas affected by SARS-CoV-2 up to 19 April 2020. Patients suspected of SARS-CoV-2 infection before operation were excluded. The primary outcome measure was postoperative pulmonary complications at 30 days after surgery. Preoperative testing strategies were adjusted for confounding using mixed-effects models. RESULTS: Of 8784 patients (432 hospitals, 53 countries), 2303 patients (26.2 per cent) underwent preoperative testing: 1458 (16.6 per cent) had a swab test, 521 (5.9 per cent) CT only, and 324 (3.7 per cent) swab and CT. Pulmonary complications occurred in 3.9 per cent, whereas SARS-CoV-2 infection was confirmed in 2.6 per cent. After risk adjustment, having at least one negative preoperative nasopharyngeal swab test (adjusted odds ratio 0.68, 95 per cent confidence interval 0.68 to 0.98; P = 0.040) was associated with a lower rate of pulmonary complications. Swab testing was beneficial before major surgery and in areas with a high 14-day SARS-CoV-2 case notification rate, but not before minor surgery or in low-risk areas. To prevent one pulmonary complication, the number needed to swab test before major or minor surgery was 18 and 48 respectively in high-risk areas, and 73 and 387 in low-risk areas. CONCLUSION: Preoperative nasopharyngeal swab testing was beneficial before major surgery and in high SARS-CoV-2 risk areas. There was no proven benefit of swab testing before minor surgery in low-risk areas

Delaying surgery for patients with a previous SARS-CoV-2 infection

Not availabl