In this study, we
have developed a method to predict the steady-state
rate and Cu oxidation state during ethylene oxychlorination from a
reaction rate diagram of the individual steps involved in the catalytic
oxychlorination cycle. The steady state of the redox cycle is represented
by a cross point of the reaction rates of the reduction and oxidation
steps as a function of the Cu2+ in the rate diagram. Transient
kinetics of elementary reactions and steady-state kinetics of the
overall catalytic cycle were investigated in an operando study using
combined mass and UV–vis-NIR spectrophotometry. The catalytic
consequence of the promoters was then evaluated in terms of reduction
and oxidation activity as well as number of active sites, site activity,
and the catalyst oxidation state at steady state. Results revealed
that the neat CuCl2 catalysts operated at low Cu2+ at the steady-state conditions with stoichiometric feed composition,
as a result of relatively low oxidation rate of Cu1+. As
a consequence of a high content of Cu1+, ethylene conversion
and selectivity are low, and the catalyst deactivates rapidly. By
the promotion of the CuCl2 catalyst by K, the reactor operates
at a high Cu2+ concentration with much improved stability
as a result of enhanced oxidation rate, but the catalyst has low activity
due to significantly reduced reduction rate. Therefore, the rate diagram
has been applied as a tool for a rational design of the CuCl2-based oxychlorination catalysts, and Ce was proposed as the promoter
due to its high promotion to the oxidation and low reactivity with
Cu ions. It was found that the activity of the Ce-promoted catalysts
increased 8 times compared to the neat CuCl2 catalyst and
moreover significantly improved the stability for the oxychlorination
catalyst at steady state, due to the enhancement of both the rates
of the reduction and oxidation. It is anticipated that the methodology
developed here paves the way for a general method for catalyst design
of heterogeneous catalysts where the catalyst undergoes oxidation
state changes, in particular in redox reactions.
Nurses need to be resilient to be able to endure their working conditions, and their moral courage can affect their resilience. This work aimed at studying the relationship between resilience and professional moral courage among nurses working in hospitals. This descriptive cross-sectional study was conducted on 375 nurses working in teaching hospitals in the city of Ardabil in Iran in 2019. Data was collected using the following questionnaires: a demographic questionnaire, Sekerka et al. Moral Courage Scale and Davidson-Connor Resilience Scale. The reliability of the Davidson-Connor Resilience Scale, and Moral Courage Scale were found to be 89% and 85% using the test-retest method. The data were analyzed by Pearson correlation coefficient, t-test, variance analysis, and linear regression using the SPSS software version 24. In participating nurses, mean scores were 6.35±0.5 for total moral courage (favorable) and 79.35±0.35 (moderate) for resilience, respectively. A positive and significant relationship was observed between resilience and professional moral courage (P<0.05, r=0.1). Given the positive and significant relationship between resilience and professional moral courage, nurses require to have the high moral courage to enhance their resilience. Determining factors affecting moral courage and resilience, as well as finding strategies and creating an appropriate moral climate can increase nurses' morally courageous behaviors and resilience.
The energy transition is the pathway to transform the global economy away from its current dependence on fossil fuels towards net zero carbon emissions. This requires the rapid and large-scale deployment of renewable energy. However, most renewables, such as wind and solar, are intermittent and hence generation and demand do not necessarily match. One way to overcome this problem is to use excess renewable power to generate hydrogen by electrolysis, which is used as an energy store, and then consumed in fuel cells, or burnt in generators and boilers on demand, much as is presently done with natural gas, but with zero emissions. Using hydrogen in this way necessitates large-scale storage: the most practical manner to do this is deep underground in salt caverns, or porous rock, as currently implemented for natural gas and carbon dioxide. This paper reviews the concepts, and challenges of underground hydrogen storage. As well as summarizing the state-of-theart, with reference to current and proposed storage projects, suggestions are made for future work and gaps in our current understanding are highlighted. The role of hydrogen in the energy transition and storage methods are described in detail. Hydrogen flow and its fate in the subsurface are reviewed, emphasizing the unique challenges compared to other types of gas storage. In addition, site selection criteria are considered in the light of current field experience.
C(3) or C(3v) symmetric enantiopure syn-tris(norborneno)benzenes with various functional groups were synthesized through Pd-catalyzed cyclotrimerization of enantiopure iodonorbornenes. The generality of Pd-catalyzed cyclotrimerization for syn-tris(norborneno)benzenes were well-demonstrated.
The growing demand for clean energy can be met by improving the recovery of current resources. One of the effective methods in recovering the unswept reserves is chemical flooding. Microemulsion flooding is an alternative for surfactant flooding in a chemical-enhanced oil recovery method and can entirely sweep the remaining oil in porous media. The efficiency of microemulsion flooding is guaranteed through phase behavior analysis and customization regarding the actual field conditions. Reviewing the literature, there is a lack of experience that compared the macroscopic and microscopic efficiency of microemulsion flooding, especially in low viscous oil reservoirs. In the current study, one-quarter five-spot glass micromodel was implemented for investigating the effect of different parameters on microemulsion efficiency, including surfactant types, injection rate, and micromodel pattern. Image analysis techniques were applied to represent the phase saturations throughout the microemulsion flooding tests. The results confirm the appropriate efficiency of microemulsion flooding in improving the ultimate recovery. LABS microemulsion has the highest efficiency, and the increment of the injection rate has an adverse effect on oil recovery. According to the pore structure’s tests, it seems that permeability has little impact on recovery. The results of this study can be used in enhanced oil recovery designs in low-viscosity oil fields. It shows the impact of crucial parameters in microemulsion flooding.
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