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1.
Aging Ment Health ; : 1-11, 2024 Apr 26.
Article in English | MEDLINE | ID: mdl-38669147

ABSTRACT

OBJECTIVES: This study aims to review the use of reminiscence interventions in the reduction of loneliness in older adults by categorising the interventions by type, and comparing their effectiveness and methodological quality. METHOD: This is a systematic review following PRISMA guidelines. The search was restricted to studies published in the Cochrane, CINAHL, Web of Science, Psycarticles, Psycinfo, and PubMed databases until December 2022. The inclusion criteria for the studies included in this review were: 1) reminiscence intervention 2) loneliness outcome measure 3) adults over 60 years old 4) experimental, pre-experimental, and quasi-experimental studies. RESULTS: A total of twelve studies were eligible for inclusion. Only nine studies included a control group, and seven of those report significant effectiveness in reducing loneliness levels. The most popular type of intervention is simple reminiscence and life review, and in-group format. The interventions to date have been very heterogeneous, and the methodological quality of the existing literature is moderate to weak. CONCLUSION: While reminiscence interventions hold some promise for reducing loneliness levels among older adults, future methodologically rigorous research is required, and standardised protocols need to be developed for application, with the specific aim of reducing levels of loneliness among older adults.

2.
Environ Sci Pollut Res Int ; 31(22): 32766-32783, 2024 May.
Article in English | MEDLINE | ID: mdl-38662292

ABSTRACT

In this study, the effect of the cell density of monolithic catalysts was investigated and further mathematically modeled on cordierite supports used in CO2 methanation. Commercial cordierite monoliths with 200, 400, and 500 cpsi cell densities were coated by immersion into an ethanolic suspension of Ni/CeO2 active phase. SEM-EDS analysis confirmed that, owing to the low porosity of cordierite (surface area < 1 m2 g-1), the Ni/CeO2 diffusion into the walls was limited, especially in the case of low and intermediate cell density monoliths; thus, active phase was predominantly loaded onto the channels' external surface. Nevertheless, despite the larger exposed surface area in the monolith with high cell density, which would allow for better distribution and accessibility of Ni/CeO2, its higher macro-pore volume resulted in some introduction of the active phase into the walls. As a result, the catalytic evaluation showed that it was more influenced by increments in volumetric flow rates. The low cell density monolith displayed diffusional control at flow rates below 500 mL min-1. In contrast, intermediate and high cell density monoliths presented this behavior up to 300 mL min-1. These findings suggest that the interaction reactants-catalyst is considerably more affected by a forced non-uniform flow when increasing the injection rate. This condition reduced the transport of reactants and products within the catalyst channels and, in turn, increased the minimum temperature required for the reaction. Moreover, a slight diminution of selectivity to CH4 was observed and ascribed to the possible formation of hot spots that activate the reverse water-gas shift reaction. Finally, a mathematical model based on fundamental momentum and mass transfer equations coupled with the kinetics of CO2 methanation was successfully derived and solved to analyze the fluid dynamics of the monolithic support. The results showed a radial profile with maximum fluid velocity located at the center of the channel. A reactive zone close to the inlet was obtained, and maximum methane production (4.5 mol m-3) throughout the monolith was attained at 350 °C. Then, linear streamlines of the chemical species were developed along the channel.


Subject(s)
Carbon Dioxide , Cerium , Nickel , Catalysis , Nickel/chemistry , Carbon Dioxide/chemistry , Cerium/chemistry , Methane , Models, Theoretical
3.
Front Surg ; 11: 1352698, 2024.
Article in English | MEDLINE | ID: mdl-38322410

ABSTRACT

Introduction: Long survivors after childhood cancer are increasing thanks to oncological improvements. Their quality of life and fertility-sparing should be considered in the early phases of each oncological pathway. Cryopreservation of ovarian tissue removed before starting gonadotoxic therapies is the only fertility sparing procedure available for prepubertal children affected by cancer and it does not affect the timing of the start of the treatment. Materials and methods: The present study shows the surgical and clinical outcomes following laparoscopic ovarian tissue collection (LOTC) for a total of 311 patients aged between 0 and 17 years old from four different European Centers. Results: Only two major complications were reported according to the Clavien Dindo classification (0.6%). Discussion: LOTC can be considered a safe procedure.

4.
Eur J Pediatr ; 183(2): 915-927, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38047962

ABSTRACT

The objective of this study is to provide practical recommendations on the management of pediatric patients with immune-mediated rheumatic diseases receiving immunosuppressive therapies. The recommendations specifically address the cases of surgery, fever, and opportunistic infections (varicella, herpes-zoster, tuberculosis, invasive fungal disease). A qualitative approach was applied. A narrative literature review was performed via Medline. Primary searches were conducted using MeSH terms and free text to identify publications on infections and vaccinations in pediatric patients with immune-mediated rheumatic diseases receiving immunosuppressive therapies. The results were presented and discussed in a nominal group meeting, comprising a committee of 12 pediatric rheumatologists from the Infection Prevention and Treatment Working Group of the Spanish Society of Pediatric Rheumatology. Several recommendations were generated. A consensus procedure was implemented via a Delphi process; this was extended to members of the Spanish Society of Pediatric Rheumatology and Spanish Society of Pediatric Infectious Disease of the Spanish Association of Pediatrics. Participants produced a score ranging from 0 (totally disagree) to 10 (totally agree). Agreement was defined as a vote ≥ 7 by at least 70% of participants. The literature review included more than 400 articles. Overall, 63 recommendations (19 on surgery, fever, and opportunistic infections) were generated and voted by 59 pediatric rheumatologists and other pediatric specialists. Agreement was reached for all 63 recommendations. The recommendations on special situations cover management in cases of surgery, fever, and opportunistic infections (varicella, herpes-zoster, tuberculosis, and invasive fungal disease).  Conclusions: Hereby, we provided consensus and updated of recommendations about the management of special situations such as surgery, fever, and opportunistic in children with immune-mediated rheumatic diseases receiving immunosuppressive therapies. Several of the recommendations depend largely on clinical judgement and specific balance between risk and benefit for each individual and situation. To assess this risk, the clinician should have knowledge of the drugs, the patient's previous situation as well as the current infectious disease, in addition to experience. What is Known: • Infectious diseases and related complications are a major cause of morbidity and mortality in patients with immune-mediated rheumatic diseases. • Information on how to manage the treatment in situations of fever, opportunistic infections, and surgery in children is limited, and guidelines for action are often extrapolated from adults. What is New: • In the absence of strong evidence, a literature review and a Delphi survey were conducted to establish a series of expert recommendations that could support the clinical practice, providing a practical and simple day-to-day approach to be used by pediatric rheumatologists.


Subject(s)
Chickenpox , Communicable Diseases , Herpes Zoster , Mycoses , Opportunistic Infections , Rheumatic Diseases , Tuberculosis , Child , Humans , Chickenpox/diagnosis , Chickenpox/prevention & control , Communicable Diseases/complications , Herpes Zoster/complications , Immunosuppression Therapy/adverse effects , Mycoses/complications , Opportunistic Infections/diagnosis , Opportunistic Infections/prevention & control , Opportunistic Infections/complications , Rheumatic Diseases/complications , Rheumatic Diseases/drug therapy , Tuberculosis/complications , Vaccination/adverse effects
7.
Life Sci ; 332: 122106, 2023 Nov 01.
Article in English | MEDLINE | ID: mdl-37730108

ABSTRACT

Cancers and cardiovascular diseases are the top two causes of death in the United States. Over the past decades, novel therapies have slowed the cancer mortality rate, yet cardiac failures have risen due to the toxicity of cancer treatments. The mechanisms behind this relationship are poorly understood and it is crucial that we properly treat patients at risk of developing cardiac failure in response to cancer treatments. Currently, we rely on early-stage biomarkers of inflammation and angiogenesis to detect cardiotoxicity before it becomes irreversible. Identification of such biomarkers allows healthcare professionals to decrease the adverse effects of cancer therapies. Angiogenesis and inflammation have a systemic influence on the heart and vasculature following cancer therapy. In the field of cardio-oncology, there has been a recent emphasis on gender and racial disparities in cardiotoxicity and the impact of these disparities on disease outcomes, but there is a scarcity of data on how cardiotoxicity varies across diverse populations. Here, we will discuss how current markers of angiogenesis and inflammation induced by cancer therapy are related to disparities in cardiovascular health.


Subject(s)
Antineoplastic Agents , Heart Failure , Neoplasms , Humans , Cardiotoxicity/etiology , Cardiotoxicity/drug therapy , Antineoplastic Agents/therapeutic use , Neoplasms/therapy , Heart Failure/drug therapy , Inflammation/drug therapy , Biomarkers
8.
Eur J Pediatr ; 182(9): 4271-4284, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37439850

ABSTRACT

This study aims to provide practical recommendations on prophylaxis for infection in pediatric patients with immune-mediated rheumatic diseases receiving/scheduled to receive immunosuppressive therapy. A qualitative approach was applied. A narrative literature review was performed via Medline. Primary searches were conducted using MeSH terms and free text to identify articles that analyzed data on infections and vaccinations in pediatric patients with immune-mediated rheumatic diseases receiving immunosuppressive therapy. The results were presented and discussed in a nominal group meeting comprising a committee of 12 pediatric rheumatologists from the Prevention and Treatment of Infections Working Group of the Spanish Society of Pediatric Rheumatology. Several recommendations were generated. A consensus procedure was implemented via a Delphi process that was extended to members of the Spanish Society of Pediatric Rheumatology and the Vaccine Advisory Committee of the Spanish Association of Pediatrics. Participants produced a score ranging from 0 (completely disagree) to 10 (completely agree). Agreement was considered to have been reached if at least 70% of participants voted ≥ 7. The literature review included more than 400 articles. Overall, 63 recommendations were generated (23 on infection prophylaxis) and voted by 59 pediatric rheumatologists and other pediatric specialists, all of whom achieved the pre-established level of agreement. The recommendations on prophylaxis of infection cover vaccination and prophylaxis against varicella zoster virus, tuberculosis, Pneumocystis jiroveccii, and invasive fungal infections in pediatric patients with immune-mediated rheumatic diseases receiving/scheduled to receive immunosuppressive therapy.  Conclusion: Based on current evidence and a Delphi process, we provided consensus and updated recommendations on prophylaxis and treatment of infections to guide those caring for pediatric rheumatology patients. What is Known: •Data largely derived from adults find that infectious diseases and related complications are a major cause of morbidity and mortality in patients with immune-mediated rheumatic diseases. •It is crucial to be aware of the preventive measures that should be implemented to prevent these infections in children, although most guidelines are often extrapolated from adult cases. What is New: •In the absence of evidence, a literature review and a Delphi survey were conducted to establish a series of expert recommendations that could prove useful in clinical practice, providing a practical and simple day-to-day approach to be used by pediatric rheumatologists. •The recommendations focus on tuberculosis, herpes zoster virus, fungal infections, and Pneumocystis jirovecii.

9.
Am J Dermatopathol ; 45(8): e61-e63, 2023 Aug 01.
Article in English | MEDLINE | ID: mdl-37378474

ABSTRACT

ABSTRACT: Self-healing juvenile cutaneous mucinosis is a rare entity, characterized by the presence of subcutaneous nodules together with frequent nonspecific systemic symptoms, which occurs in the pediatric age and characteristically resolves spontaneously. Although the diagnostic criteria do not require a biopsy to be performed, it is frequently performed, and an abundant dermal mucin deposition will be observed together with other features such as fibroblastic proliferation. Although the prognosis is benign, follow-up is required for the eventual development of a rheumatologic disease.We present 2 clinical cases, describing the clinical findings and their histopathologic correlation. Comparatively, the outcome in both cases was different: in one case, the mucinosis resolved without any related event in the follow-up, and in the other case, the resolution was accompanied by the subsequent development of idiopathic juvenile arthritis.


Subject(s)
Arthritis, Juvenile , Mucinoses , Skin Diseases , Humans , Child , Mucinoses/pathology , Biopsy , Mucins
10.
Eur J Trauma Emerg Surg ; 49(4): 1969-1979, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37000193

ABSTRACT

PURPOSE: Substance misuse has long been recognized as a major predisposing risk factor for traumatic injury. However, there still exists no clear scientific consensus regarding the impact of drug use on patient outcomes. Therefore, this study aims to evaluate the demographic profile, hospital-course factors, and outcomes of trauma patients based on their toxicology. METHODS: This is a non-concurrent cohort study of 3709 patients treated at the Puerto Rico Trauma Hospital during 2002-2018. The sample was divided into four groups according to their toxicology status. Statistical techniques used included Pearson's chi-square test, Spearman correlation, and negative binomial and logistic regressions. RESULTS: Admission rates for marijuana (rho = 0.87) and marijuana and cocaine positive (rho = 0.68) patients increased. Positive toxicology patients underwent surgery more often than negative testing patients (marijuana: 68.7%, cocaine: 65.6%, marijuana & cocaine: 69.8%, negative: 57.0%). Among patients with non-penetrating injuries, a positive toxicology for cocaine or marijuana was linked to a 48% and 42% increased adjusted risk of complications, 37% and 27% longer TICU LOS, and 32% and 18% longer hospital LOS, respectively. CONCLUSION: Our results show an association between positive toxicology for either marijuana, cocaine, or both with higher need for surgery. Additionally, our results show an increase in complications, TICU LOS, and hospital LOS among non-penetrating trauma patients testing positive for marijuana or cocaine. Therefore, this study provides valuable information on the clinical profile of patients with positive toxicology, suggesting they might benefit from more aggressive management.


Subject(s)
Cannabis , Cocaine , Wounds and Injuries , Humans , Cannabis/adverse effects , Cocaine/adverse effects , Cohort Studies , Risk Factors , Substance-Related Disorders/complications , Wounds and Injuries/complications , Wounds and Injuries/physiopathology
11.
Talanta ; 253: 123829, 2023 Feb 01.
Article in English | MEDLINE | ID: mdl-36087410

ABSTRACT

Thermal Extraction-Desorption (TED) using a thermobalance coupled to a gas chromatograph (GC) with mass spectrometer (MS) detector is an extended method for polymers identification in complex matrixes. A new TED-GC/MS method for microplastics identification is developed in this study, where the whole filter with solids collected from water is thermal treated in a furnace, instead of using a small portion in a Thermogravimetric analysis (TGA) device, avoiding sample handling. Pyrolyzing the whole filter in a tubular furnace has advantages with respect to the standard procedure of using a TGA with a small crucible in TED-GC/MS. The main advantage is the easy manipulation of the sample, since the filter does not have to be manipulated to extract the sample or cut some portions, avoiding sample losses during handling and ensuring that inhomogeneity on the filter surface is not a problem. Furthermore, there are no limitations on the weight of the sample beyond the adsorbent's ability to trap decomposition compounds without becoming saturated, so high intensity signals can be obtained in order to avoid confuse signals with noise, false negatives or values so close of the quantification limit.


Subject(s)
Microplastics , Water , Gas Chromatography-Mass Spectrometry , Plastics
13.
Eur J Pediatr ; 181(6): 2343-2354, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35258699

ABSTRACT

This study provides practical recommendations on infection screening in pediatric patients with immune-mediated rheumatic diseases and immunosuppressive therapies. For this reason, a qualitative approach was applied. A narrative literature review was performed via Medline. Primary searches were conducted using Mesh and free texts to identify articles that analyzed data on infections and vaccinations in pediatric patients with immune-mediated rheumatic diseases and immunosuppressive therapies. The results were presented and discussed in a nominal group meeting, comprising a committee of 12 pediatric rheumatologists from the infections prevention and treatment working group of the Spanish Society of Pediatric Rheumatology. Several recommendations were generated. A consensus procedure was implemented via a Delphi process that was extended to members of the Spanish Society of Pediatric Rheumatology and Vaccine Advisory Committee of the Spanish Association of Pediatrics. Participants to the process produced a score ranging from 0 = totally disagree to 10 = totally agree. Agreement was considered if at least 70% of participants voted ≥ 7. The literature review included more than 400 articles. Overall, 63 recommendations were generated (21 on infection screening) voted by 59 pediatric rheumatologists and other pediatric specialists, all of them achieving the pre-established agreement level. The recommendations on screening cover all the procedures (serology, assessment of risk factors, and other clinical activities) connected with the screening for infections including tuberculosis; hepatitis A, B, and C viruses; measles; mumps; rubella; diphtheria; and other infections. Conclusion: Screening for infections is an essential part of risk management in pediatric patients with immune-mediated rheumatic diseases and immunosuppressive therapies. What is Known: • Infectious diseases and related complications are a major cause of morbidity and mortality in patients with immune-mediated rheumatic diseases. • At present, practical information on infectious prophylaxis in children with rheumatic diseases is limited, and often extrapolated from children with cancer. What is New: • In the absence of evidence, a literature review and a Delphi survey were conducted to establish a series of expert recommendations that would be useful in clinical practice, providing a practical and simple day-to-day approach to be used by pediatric rheumatologists.


Subject(s)
Pediatrics , Rheumatic Diseases , Rheumatology , Child , Humans , Immunosuppression Therapy , Rheumatic Diseases/complications , Rheumatic Diseases/drug therapy , Vaccination
14.
Pediatr Pulmonol ; 57(1): 253-263, 2022 01.
Article in English | MEDLINE | ID: mdl-34633153

ABSTRACT

OBJECTIVES: To describe the etiology of community-acquired pneumonia (CAP) in hospitalized children in Spain and analyze the predictors of the etiology. HYPOTHESIS: The different etiological groups of pediatric CAP are associated with different clinical, radiographic, and analytical data. DESIGN: Observational, multicenter, and prospective study. PATIENT SELECTION: This study included children aged 1 month to 17 years with CAP, who were hospitalized between April 2012 and May 2019. METHODS: An extensive microbiological workup was performed. The clinical, radiographic, and analytical parameters were analyzed for three etiological groups. RESULTS: Among the 495 children included, at least one causative pathogen was identified in 262 (52.9%): pathogenic viruses in 155/262 (59.2%); atypical bacteria (AB), mainly Mycoplasma pneumonia, in 84/262 (32.1%); and typical bacteria (TyB) in 40/262 (15.3%). Consolidation was observed in 89/138 (64.5%) patients with viral CAP, 74/84 (88.1%) with CAP caused by AB, and 40/40 (100%) with CAP caused by TyB. Para-pneumonic pleural effusion (PPE) was observed in 112/495 (22.6%) patients, of which 61/112 (54.5%) presented a likely causative pathogen: viruses in 12/61 (19.7%); AB in 23/61 (37.7%); and TyB in 26/61 (42.6%). Viral etiology was significantly frequent in young patients and in those with low oxygen saturation, wheezing, no consolidation, and high lymphocyte counts. CAP patients with AB as the etiological agent had a significantly longer and less serious course as compared to those with other causative pathogens. CONCLUSIONS: Viruses and M. pneumoniae are the main causes of pediatric CAP in Spain. Wheezing, young age, and no consolidation on radiographs are indicative of viral etiology. Viruses and AB can also cause PPE. Since only a few cases can be directly attributed to TyB, the indications for antibiotics must be carefully considered in each patient.


Subject(s)
Community-Acquired Infections , Pneumonia, Mycoplasma , Viruses , Child , Community-Acquired Infections/epidemiology , Humans , Mycoplasma pneumoniae , Oxygen Saturation , Pneumonia, Mycoplasma/complications , Pneumonia, Mycoplasma/epidemiology , Prospective Studies , Spain/epidemiology
15.
Clin Rehabil ; 36(1): 4-14, 2022 Jan.
Article in English | MEDLINE | ID: mdl-34407619

ABSTRACT

OBJECTIVE: This systematic review and meta-analysis investigates the effects of strength training program in children and adolescents with cerebral palsy to improve function, activity, and participation. DATA SOURCES: Five electronic databases (MEDLINE-Pubmed, Cochrane Library, PEDro, CINAHL, and SPORTDiscus) were systematically searched for full-text articles published from inception to 30 June 2021. REVIEW METHODS: Randomized controlled trials were included, who compared: (i) child population with spastic cerebral palsy population between 0 and 22 years; (ii) studies in which a muscle strength training program was performed and included dosing information; (iii) studies comparing strength training with other physical therapy technique(s) or untreated control group. Studies with similar outcomes were pooled by calculating standardized mean differences. Risk of bias was assessed with Cochrane Collaboration's tool for assessing the risk of bias and PROSPERO's registration number ID: CRD42020193535. RESULTS: Twenty-seven studies, comprising 847 participants with spastic cerebral palsy. The meta-analyses demonstrated significant standardized mean differences in favor of strength training program compared to other physical therapy technique(s) or untreated control group(s) for muscle strength at the knee flexors, at the knee extensor, at the plantarflexors, maximum resistance, balance, gait speed, GMFM (global, D and E dimension) and spasticity. CONCLUSION: A strength training program has positive functional and activity effects on muscle strength, balance, gait speed, or gross motor function without increasing spasticity for children and adolescents with cerebral palsy in Gross Motor Function Classification System levels I, II, and III when adequate dosage and specific principles are utilized.


Subject(s)
Cerebral Palsy , Resistance Training , Adolescent , Child , Humans , Muscle Strength , Muscles , Walking Speed
16.
Pediatr Infect Dis J ; 41(1): 31-36, 2022 01 01.
Article in English | MEDLINE | ID: mdl-34524234

ABSTRACT

BACKGROUND: Establishing the etiology of community-acquired pneumonia (CAP) in children at admission is challenging. Most of the admitted children with CAP receive antibiotics. We aimed to build and validate a diagnostic tool combining clinical, analytical and radiographic features to differentiate viral from bacterial CAP, and among bacterial CAP, typical from atypical bacteria. METHODS: Design-observational, multi-center, prospective cohort study was conducted in 2 phases. Settings: 24 secondary and tertiary hospitals in Spain. Patients-A total of 495 consecutive hospitalized children between 1 month and 16 years of age with CAP were enrolled. Interventions-A score with 2 sequential steps was built (training set, 70% patients, and validation set 30%). Step 1 differentiates between viral and bacterial CAP and step 2 between typical and atypical bacterial CAP. Optimal cutoff points were selected to maximize specificity setting a high sensitivity (80%). Weights of each variable were calculated with a multivariable logistic regression. Main outcome measures-Viral or bacterial etiology. RESULTS: In total, 262 (53%) children (median age: 2 years, 52.3% male) had an etiologic diagnosis. In step 1, bacterial CAPs were classified with a sensitivity = 97%, a specificity = 48%, and a ROC's area under the curve = 0.81. If a patient with CAP was classified as bacterial, he/she was assessed with step 2. Typical bacteria were classified with a sensitivity = 100%, a specificity = 64% and area under the curve = 0.90. We implemented the score into a mobile app named Pneumonia Etiology Predictor, freely available at usual app stores, that provides the probability of each etiology. CONCLUSIONS: This 2-steps tool can facilitate the physician's decision to prescribe antibiotics without compromising patient safety.


Subject(s)
Community-Acquired Infections/diagnosis , Community-Acquired Infections/etiology , Mobile Applications/standards , Pneumonia, Bacterial/diagnosis , Pneumonia, Viral/diagnosis , Adolescent , Child , Child, Preschool , Community-Acquired Infections/microbiology , Community-Acquired Infections/virology , Female , Humans , Infant , Logistic Models , Male , Pneumonia, Bacterial/diagnostic imaging , Pneumonia, Viral/diagnostic imaging , Prospective Studies , Radiography/methods , Radiography/standards
17.
J Phys Chem C Nanomater Interfaces ; 125(46): 25533-25544, 2021 Nov 25.
Article in English | MEDLINE | ID: mdl-34868445

ABSTRACT

This study addresses the yet unresolved CO2 methanation mechanism on a Ru/CeO2 catalyst by means of near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) complemented with periodic density functional theory (DFT) calculations. NAP-XPS results show that the switch from H2 to CO2 + H2 mixture oxidizes both the Ru and CeO2 phases at low temperatures, which is explained by the CO2 adsorption modes assessed by means of DFT on each representative surface. CO2 adsorption on Ru is dissociative and moderately endergonic, leading to polybonded Ru-carbonyl groups whose hydrogenation is the rate-determining step in the overall process. Unlike on Ru metal, CO2 can be strongly adsorbed as carbonates on ceria surface oxygen sites or on the reduced ceria at oxygen vacancies as carboxylates (CO2 -δ), resulting in the reoxidation of ceria. Carboxylates can then evolve as CO, which is released either via direct splitting at relatively low temperatures or through stable formate species at higher temperatures. DRIFTS confirm the great stability of formates, whose depletion relates with CO2 conversion in the reaction cell, while carbonates remain on the surface up to higher temperatures. CO generation on ceria serves as an additional reservoir of Ru-carbonyls, cooperating to the overall CO2 methanation process. Altogether, this study highlights the noninnocent role of the ceria support in the performance of Ru/CeO2 toward CO2 methanation.

18.
J Phys Chem C Nanomater Interfaces ; 125(22): 12038-12049, 2021 Jun 10.
Article in English | MEDLINE | ID: mdl-34630817

ABSTRACT

CO2 methanation has been studied with Pr-doped Ru/CeO2 catalysts, and a dual effect of Pr has been observed. For low Pr content (i.e., 3 wt %) a positive effect in oxygen mobility prevails, while for high Pr doping (i.e., 25 wt %) a negative effect in the Ru-CeO2 interaction is more relevant. Isotopic experiments evidenced that Pr hinders the dissociation of CO2, which takes place at the Ru-CeO2 interface. However, once the temperature is high enough (200 °C), Pr improves the oxygen mobility in the CeO2 support, and this enhances CO2 dissociation because the oxygen atoms left are delivered faster to the support sink and the dissociation sites at the interface are cleaned up faster. In situ Raman spectroscopy experiments confirmed that Pr improves the creation of oxygen vacancies on the ceria lattice but hinders their reoxidation by CO2, and both opposite effects reach an optimum balance for 3 wt % Pr doping. In addition, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments showed that Pr doping, regardless of the amount, decreases the population of surface carbon species created on the catalysts surface upon CO2 chemisorption under methanation reaction conditions, affecting both productive reaction intermediates (formates and carbonyls) and unproductive carbonates.

19.
ACS Sustain Chem Eng ; 9(18): 6329-6336, 2021 May 10.
Article in English | MEDLINE | ID: mdl-34567850

ABSTRACT

Cryptomelane is an abundant mineral manganese oxide with unique physicochemical features. This work investigates the real capabilities of cryptomelane as an oxidation catalyst. In particular, the preferential CO oxidation (CO-PROX), has been studied as a simple reaction model. When doped with copper, the cryptomelane-based material has revealed a great potential, displaying a comparable activity to the high-performance CuO/CeO2. Despite stability concerns that compromise the primary catalyst reusability, CuO/cryptomelane is particularly robust in the presence of CO2 and H2O, typical components of realistic CO-PROX streams. The CO-PROX reaction mechanism has been assessed by means of isotopic oxygen pulse experiments. Altogether, CuO/CeO2 shows a greater oxygen lability, which facilitates lattice oxygen enrolment in the CO-PROX mechanism. In the case of CuO/cryptomelane, in spite of its lower oxygen mobility, the intrinsic structural water co-assists as active oxygen species involved in CO-PROX. Thus, the presence of moisture in the reaction stream turns out to be beneficial for the stability of the cryptomelane structure, besides aiding into the active oxygen restitution in the catalyst. Overall, this study proves that CuO/cryptomelane is a promising competitor to CuO/CeO2 in CO-PROX technology, whose implementation can bring the CO-PROX technology and H2 purification processes a more sustainable nature.

20.
Materials (Basel) ; 14(17)2021 Sep 02.
Article in English | MEDLINE | ID: mdl-34501105

ABSTRACT

Honeycomb monoliths are the preferred supports in many industrial heterogeneous catalysis reactions, but current extrusion synthesis only allows obtaining parallel channels. Here, we demonstrate that 3D printing opens new design possibilities that outperform conventional catalysts. High performance carbon integral monoliths have been prepared with a complex network of interconnected channels and have been tested for carbon dioxide hydrogenation to methane after loading a Ni/CeO2 active phase. CO2 methanation rate is enhanced by 25% at 300 °C because the novel design forces turbulent flow into the channels network. The methodology and monoliths developed can be applied to other heterogeneous catalysis reactions, and open new synthesis options based on 3D printing to manufacture tailored heterogeneous catalysts.

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