Nanocatalysts from Ionic Liquid Precursors for CO2 Valorisation to Hydrocarbons

The conversion of CO2 into lower olefins (C3-C5) is a highly desirable process as a sustainable production route. Thereby, the use of hydrogen from renewable energies and the conversion of CO2 into lower olefins via Fischer-Tropsch synthesis (FTS) offers an attractive route for efficient utilisation of biogas as a renewable feedstock to replace petroleum for the synthesis of key building-block chemicals. Lower olefins, i.e., ethylene, propylene and butene (C2-C4) are key building blocks in the current chemical industry. Iron-based catalysts are of interest due to their ability to catalyse both FTS and Reverse Water Gas Shift (RGS). These are also of interest as they are able to produce high olefin hydrocarbons. The main reason for the iron catalyst effectiveness in such process is its formation of iron carbides (χ-Fe5C2) formed after reaction gas treatment. It has also been reported that the iron catalysts require alkali metal promotion in order to obtain desired activity and selectivity. The further upgrading to gasoline range hydrocarbons can be done by having zeolites in close proximity to the iron catalysts. It has been proposed that the zeolites crack lower chain olefins, and able to facilitate chain growth.However, for such catalysts, controlling the size and the particle distribution remains a major challenge. Thus, in order to obtain monodispersed catalysts, a novel approach is developed, utilising ionic liquids which can dissolve precursors while itself containing dense and tuneable network of hydrogen bonds. Such synthetic methods have been demonstrated by Wang et al. Nanoparticles produced through this method have been shown to produce higher surface areas. We report here on a novel methodology for the controlled synthesis of a Na–Fe3O4/HZSM-5 multifunctional catalyst for the direct hydrogenation of CO2 to gasoline. The catalytic testing under industrially relevant conditions resulted in improved selectivity to C5–C11 as well as low CH4 and CO2 selectivity. Furthermore, the product composition can be tuned by the zeolite properties (i.e. Si/Al ratio, H form, alkaline exchange) and by the choice of ionic liquid in the synthetic method. This study provides a new pathway for the synthesis of nanocatalysts for the production of liquid fuels by utilising CO2 and H2

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Function, structure and reactivity relationships in knoevenagel condensation reactions

A Knoevenagel condensation reaction between ethyl cyanoacetate and benzaldehyde catalysed by Mg and Ba impregnated oxide matrices (SiO₂, Al₂O₃, Fe2O3, and ZnO). The role of the support nature in the Knoevenagel condensation activity is considered, comparing the reaction rates. The intrinsic activity of the catalysts was compared by normalising the reaction rates to the specific surface area, and relating with the partial charges of the metal and oxide species, based on the Sanderson electronegativity calculations. Results show that a general correlation can be seen with the activity and the partial charges of the species providing some insight towards acid-base site relationships. ZnO however is to be considered differently as it does not follow the correlation

Base catalysed transesterification processes using magnesium and barium oxide composites

Oil is a finite resource and there are concerns that it may peak in the near future. For this reason, it is important to investigate alternative fuel resources. Of these resources, biodiesel in particular will be examined. Biodiesel production processes requires the use of liquid bases to initiate the reaction, but they cannot be reused. By-product in the form of soap is usually seen when liquid bases are used, reducing the quality of the biodiesel. Steps are taken to remove both the base and unwanted products from the reaction mixture, but see a reduced biodiesel product and added expenditures. The steps can be avoided by using a stable solid catalyst. Our catalyst consists of a magnesium and barium oxide composite. For physical characterization, SEM, FT-IR and XRD was performed. Alkalinity characterization was performed with CO2-TPD. The catalyst was used in a biodiesel production analogue, with ethyl acetate and methanol at 60˚C and under inert atmosphere. Reaction samples were withdrawn periodically and analysed using gas chromatography. Leaching tests were performed to confirm the catalyst resistance to leaching. Results show the catalyst produced product conversions of 30% in the initial 6 hours, and increased to 88% at 24 hours. The catalyst also showed no signs of leaching. The success of the catalyst demonstrates potential for biodiesel production. Kinetic studies should be made in order to observe the optimal conditions the catalyst operates under. This can be followed up with reactions firstly with pure triglycerides, followed by reaction with vegetable oils

Oxidative coupling and hydroxylation of phenol over transition metal and acidic zeolites: insights into catalyst function

Reaction of phenol with hydrogen peroxide over H-MFI, Fe-MFI, H-BEA, Fe-BEA and TS-1 zeolite catalysts was investigated. Over H-BEA, biphenyl product was observed. It is suggested, that the larger pore size of H-BEA facilitates coupling of two phenol molecules. Two distinct reaction mechanisms are proposed for acid and redox catalysts

In A Mechanistic Insight of n-Butanol Oxidation Reaction over Ruthenium Catalysts Using in Situ FTIR and XPS Techniques

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Insight into Composition and Intermediate Evolutions of Copper-Based Catalysts during Gas-Phase CO2 Electroreduction to Multicarbon Oxygenates

Conversion of CO2 to valuable chemicals driven by renewable electricity via electrocatalytic reduction processes is of great significance for achieving carbon neutrality. Copper-based materials distinguish themselves from other electrocatalysts for their unique capability to produce multicarbon compounds in CO2 electroreduction. However, the intrinsic active composition and C&ndash;C coupling mechanism of copper-based catalysts are still ambiguous. This is largely due to the absence of appropriate in situ approaches to monitor the complicated processes of CO2 electroreduction. Here, we adopted operando spectroscopy techniques, including Raman and infrared, to investigate the evolution of compositions and intermediates during gas-phase CO2 electroreduction on Cu foam, Cu2O nanowire and CuO nanowire catalysts. Although all the three copper-based catalysts possessed the activity of electroreducing gas-phase CO2 to multicarbon oxygenates, Cu2O nanowires showed the much superior performance with a 71.9% Faradaic efficiency of acetaldehyde. Operando Raman spectra manifested that the cuprous oxide remained stable during the whole gas-phase CO2 electroreduction, and operando diffuse reflectance infrared Fourier transform spectroscopy (DRFITS) results provide direct evidences of key intermediates and their evolutions for producing multicarbon oxygenates, in consistence with the density functional theory calculations

Engineering plasticization resistant gas separation membranes using metal–organic nanocapsules

Membrane technologies hold great potential for industrial gas separation. Nevertheless, plasticization, a common phenomenon that is responsible for the loss of gas pair selectivity and the decrease of membrane lifespan, is one of the top challenges withholding the deployment of advanced membrane materials in realistic applications. Here, we report a highly generalizable approach, that utilizes PgC(5)Cu, a copper metal–organic nanocapsule (MONC) containing 24 open metal sites (OMSs) as a multi-dentate node to coordinatively crosslink polymers. By adding merely 1–3 wt% of PgC(5)Cu, a wide range of carbonyl group-containing polymers can be effectively crosslinked. Through rigorous dissolution tests, molecular dynamic simulations, and in situ FT-IR spectroscopy, we qualitatively and quantitatively unveiled the coordinative binding nature at the polymer–MONC interface. As a result, we produced a series of composite membranes showing near complete plasticization resistance to CO(2), C(2)H(4), and C(2)H(6) under high pressure with no loss of mechanical and gas transport properties

A designed organic-zeolite hybrid acid-base catalyst

An organic–zeolite hybrid catalyst was synthesised via solid-state impregnation of the zeolite with an amount of melamine corresponding to 20 mol% of the aluminium content. A high density of basic sites is formed in the zeolite. From infrared spectroscopy and TGA measurements we infer that melaminium cations are formed in the zeolite which are highly thermally stable. IR spectroscopic and TGA measurements showed the presence of melaminium after pre-treatment in vacuum at 450°C. The catalyst exhibited activity in the Knoevenagel condensation reaction between benzaldehyde and ethyl cyanoacetate which is suggested to be promoted by the presence of acid and base sites. The catalyst activity was compared with other known base catalysts including hydrotalcites and magnesium oxide on alumina support