Glucose-derived carbon/carbon nanotube (CNT) hybrid materials were prepared by hydrothermal carbonization of glucose in the presence of CNTs and subsequent carbonization, physical activation, or ...chemical activation. The proportion of CNTs added during the hydrothermal polymerization of glucose was varied to ascertain the optimum dose to maximize the performance of the carbon hybrids in supercapacitor applications. Both the thermal treatment applied and the addition of CNTs lead to changes in the textural and chemical properties of the activated carbons. It was observed that samples bearing CNTs exhibit higher number of nucleation centers for glucose oligomers to polymerize, and consequently, the behavior of the hydrothermal carbon toward activation differs according to the activating agent employed. Moreover, the initial chemical speciation dominated by acidic groups shifts to more basic functionalities (quinones and carbonyl groups) with the addition of CNTs. The effect of the different physicochemical properties of the prepared carbons on their electrochemical behavior was evaluated. The addition of 2 wt % of CNTs and subsequent chemical activation leads to electrode materials yielding 206 F g–1 and 78% of capacitance retention up to 0.8 V and 20 A g–1 and high rate cyclability (97% after 5000 cycles). The outstanding performance is ascribed to the high surface area, narrow mesopores, and phenol/carbonyl surface functionalities, which enhance molecular diffusion, the amount of stored energy, and electronic transportation, respectively.
A facile and eco-friendly approach using in situ-generated 4-benzenediazonium sulfonate (BDS) was applied to prepare highly functionalized carbon nanotubes (CNTs). The effectiveness of this ...functionalization was additionally enhanced by a green and short-time ball milling process applied beforehand. The obtained BDS-modified CNTs presented significant activity in glycerol etherification, producing tert-butyl glycerol ethers, which are considered promising fuel additives. Excellent results of ~56% glycerol conversion and ~10% yield of higher-substituted tert-butyl glycerol ethers were obtained within just 1 h of reaction at 120 °C using a low catalyst loading of only 2.5 wt.%. Furthermore, the sulfonated CNTs were reusable over several reaction cycles, with only a minor decrease in activity. Additionally, the sample activity could be restored by a simple regeneration approach. Finally, a clear correlation was found between the content of -SO
H groups on the surface of CNTs and the catalytic performances of these materials in glycerol etherification. Improved interaction between functionalized ball-milled CNTs and the reactants was also suggested to positively affect the activity of these catalysts in the tested process.
Different lanthanide (Ln)-doped cerium oxides (Ce0.5Ln0.5O1.75, where Ln: Gd, La, Pr, Nd, Sm) were loaded with Cu (20 wt. %) and used as catalysts for the oxidation of ethyl acetate (EtOAc), a common ...volatile organic compound (VOC). For comparison, both Cu-free (Ce-Ln) and supported Cu (Cu/Ce-Ln) samples were characterized by N₂ adsorption at -196 °C, scanning/transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and temperature programmed reduction in H₂. The following activity sequence, in terms of EtOAc conversion, was found for bare supports: CeO₂ ≈ Ce0.5Pr0.5O1.75 > Ce0.5Sm0.5O1.75 > Ce0.5Gd0.5O1.75 > Ce0.5Nd0.5O1.75 > Ce0.5La0.5O1.75. Cu addition improved the catalytic performance, without affecting the activity order. The best catalytic performance was obtained for Cu/CeO₂ and Cu/Ce0.5Pr0.5O1.75 samples, both achieving complete EtOAc conversion below ca. 290 °C. A strong correlation was revealed between the catalytic performance and the redox properties of the samples, in terms of reducibility and lattice oxygen availability. Νo particular correlation between the VOC oxidation performance and textural characteristics was found. The obtained results can be explained in terms of a Mars-van Krevelen type redox mechanism involving the participation of weakly bound (easily reduced) lattice oxygen and its consequent replenishment by gas phase oxygen.
Health tourism is recognised as a growing industry. Therefore, sustainable development in health tourism is crucial not only for the well-being of patients but also for destinations and communities. ...In this sense, sustainable development in health tourism aims to develop solutions related to the environmental, social, and economic challenges faced by the country and the tourism sector. After the COVID-19 pandemic, health tourism has become popular, and despite the increase in research related to the theme, the existing literature is still relatively fragmented and lacks a comprehensive view. This study addresses this gap by investigating sustainable development in health tourism through a systematic literature review. Ninety-three articles were collected from the Web of Science database. After subjecting them to bibliometric analysis, it is possible to examine the topic’s current state of the art. This research permits the systematisation of the existing literature into five areas: (1) stakeholders of sustainable tourism, (2) impact of COVID-19, (3) health tourism, (4) challenges and opportunities, and (5) sustainability values. This research provides significant contributions to the field of sustainable development in health tourism. Firstly, it sheds light on aspects that previous literature has examined, offering valuable insights into the drivers of sustainable development in health tourism, thus enriching our comprehension of the subject. Additionally, the article delineates a prospective research agenda, suggesting various directions that can lay the foundation for upcoming inquiries and the development of pertinent theories for assessing the impact of sustainable development in health tourism.
•P-doped carbon xerogels (CX_P) are effective in fructose dehydration to HMF in water.•Thermal treatments tune the surface chemistry of CX_P.•An excellent yield of 73.3% was obtained in the green ...H2O-CO2 system.•Selectivity to HMF was correlated with the total amount of O-functionalities.•High concentration of thermally stable O- functionalities improved HMF yield.
Dehydration of fructose to 5-hydroxymethylfurfural (HMF) is a critical step in the cost-effective cascade conversion of biomass-feedstocks to advanced biofuels, fuel additives, biopolymers, and biochemicals. In this work, the surface chemistry of phosphorus-doped carbon xerogels (CX_P) was studied to identify the ways to boost their catalytic performance in the eco-friendly production of HMF. An excellent HMF yield of 73.3% from dehydration of fructose was obtained in just 2 h in the H2O-CO2 reaction system, using CX_P thermally treated in air. This was achieved by controlling the amount and type of active sites on the catalyst surface and by modifying of the reaction atmosphere. The best-performing catalyst exhibited Brønsted acids in the form of P-OH in proximity to high amounts of thermally stable oxygen functionalities such as phenol, carbonyl, and lactone, which were vital for obtaining a high yield of HMF. A positive correlation was obtained between the selectivity towards HMF and the total amount of oxygen present in the bulk of the catalysts. The oxygen groups improved selectivity towards HMF by hindering its further adsorption and degradation. In addition, the selectivity to HMF was dependnt on the ratio between O-functionalities and PO phosphates together with COP species. We finally demonstrated a superior green catalytic system to promote fructose dehydration to HMF under green conditions using pure water under a CO2 atmosphere.
Calcium-hydroxyapatite and calcium-fluoroapatite loaded with different amounts of nickel were synthesized and characterized by several techniques including scanning electron microscopy, temperature ...programmed reduction (TPR), UV–visible–NIR and XPS spectroscopy. Three types of nickel species were detected in the two series of catalysts (i) Ni
2+ ions exchanged with Ca
2+ ions of the apatite framework. This Ni
2+/Ca
2+ exchange seems to be restricted to nickel loadings inferior to 1
wt% Ni, (ii) small particles of NiO exhibiting strong interactions with the carriers (for
x
>
1
wt% Ni) and (iii) large particles of NiO which appear at high loadings. The distribution of the nickel between these three hosting sites depends on the nature of the apatite. For instance the amount of exchanged Ni
2+ ions in Ni(1)/CaHAp is twice more important than in Ni(1)/CaFAp.
The Ni(
x)/CaHAp and Ni(
x)/CaFAp catalysts were tested in methane dry reforming with CO
2. Methane conversion at 600
°C, increases with the nickel loading up to
x
=
4 where the activity is around the thermodynamic equilibrium (78%) and H
2/CO ratio close to 1. These results were confirmed by the investigation of the catalysts activity versus the temperature. Carbon deposition on the catalysts was found to also increase with nickel loading but without provoking any significant decay of the activity after 4
h on stream. The encouraging results achieved were attributed to the synergy between the basic properties of the apatites, their aptitude to chemisorb CO
2 and the catalytic features of the supported nickel.
Ni(
x)/CaHAP and Ni(
x)/CaFAP were prepared and characterized using electron microscopy, TPR, UV–visible–NIR and XPS spectroscopy. Three species of nickel were identified and their distribution in the catalysts varied with the nature of the apatite. At all temperatures, the catalysts performance in methane dry reforming, was managed by thermodynamics and appeared as good as that of Mg–Ni/Al
2O
3.
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Purpose
Companies need to innovate to remain in the market and be competitive. Thus, success will depend on your internal resources and the external sources of knowledge used. The cooperation between ...univerity and industry (U–I) allows companies to access resources that, in general, they do not have, allowing them to achieve innovation, competitive advantages, and competitiveness. The purpose of this study is to understand the determinants that influence U–I cooperation in creating knowledge and innovation.
Design/methodology/approach
This study analyzes the determinants considered essential for companies to establish cooperation processes with universities. The research uses the last community innovation survey data set, data from 14 countries, and 28,743 observations. The method uses logistic regression.
Findings
The results confirm that the company's size, the innovative capacities associated with R&D, exportation and public funds are essential and significant determinants for the cooperation with universities. On the other hand, the acquisition of machinery and training programs are not a critical factor in establishing cooperation with universities that are not in the same country. The analysis considered companies cooperation with universities of the same country, from the European Union (EU) or other countries outside EU.
Originality/value
In addition to providing substantial theoretical contributions on the subject, this research also provides more information about the importance of U–I cooperation, allowing to characterize companies interested in developing U–I cooperation.
Environmental issues urge for the substitution of petrochemical-based raw materials with more environmentally friendly sources. The biggest advantages of PLA over non-biodegradable plastics are that ...it can be produced from natural sources (e.g., corn or sugarcane), and at the end of its lifetime it can be returned to the soil by being composted with microorganisms. PLA can easily substitute petroleum-based plastics in a wide range of applications in many commodity products, such as disposable tableware, packaging, films, and agricultural twines, partially contributing to limiting plastic waste accumulation. Unfortunately, the complete replacement of fossil fuel-based plastics such as polyethylene (PE) or poly(ethylene terephthalate) (PET) by PLA is hindered by its higher cost, and, more importantly, slower degradation as compared to other degradable polymers. Thus, to make PLA more commercially attractive, ways to accelerate its degradation are actively sought. Many good reviews deal with PLA production, applications, and degradation but only in the medical or pharmaceutical field. In this respect, the present review will focus on controlled PLA degradation and biodegradation in technical applications. The work will include the main degradation mechanisms of PLA, such as its biodegradation in water, soil, and compost, in addition to thermal- and photo-degradation. The topic is of particular interest to academia and industry, mainly because the wider application of PLA is mostly dependent on discovering effective ways of accelerating its biodegradation rate at the end of its service life without compromising its properties.
Porous carbon materials can be used in catalysis either as catalysts or supports. The most relevant literature on this topic is reviewed, emphasizing the methods used for tuning the surface chemistry ...and textural properties of the carbon materials, in order to design improved catalysts.
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