Current Catalysis - Volume 9, Issue 2, 2020

We have developed an efficient, novel one-pot multicomponent protocol for the synthesis of hexahydro-4H-indazol-4-onederivatives using β-cyclodextrin as a biomimetic catalyst in an aqueous medium. To the best of our knowledge, the targeted molecules have not been reported in the literature till now. The present method is very effective for our densely functionalized and diversified targeted molecules and includes several advantages like environment benign, cost-effectiveness, short reaction times, high yields and recyclability of the catalyst.

Introduction: Due to energy demand concerns, diesel engines have gained much attraction recently compared to petrol engines because of their higher thermal efficiencies. However, they emit a larger amount of NOx emissions into the atmosphere. Objective: Nitrogen oxides are known as important ambient air pollutants that are responsible for health problems, forest damage, and buildings corrosion. Therefore, using emissions control strategies for diesel engines is required in order to have a cleaner environment. Urea-SCR (selective catalytic reduction of NOxby urea) after-treatment system is considered as one of the most efficient techniques available to reduce engine-out NOx emissions sufficiently. Conclusion: This review article discusses all the methods suggested to diminish nitrogen oxides emissions and then presents a comprehensive survey on developing urea-SCR unit -whether from catalyst development aspect or from injection system modification point of view- in diesel engines to meet strict emissions regulations.

Furan and its derivatives find wide-spread application as pharmaceuticals, pigments, dyes, brighteners, flavour & fragrance compounds and insecticides. They also exhibit antihyperglycemic, analgesic, anti-inflammatory, anti-bacterial, anti-fungal and anti-tumour activities. Silver catalysts are nowadays commonly used in organic synthesis due to the high oxidation potential and versatile nature of silver complexes. In this review, we summarise the recent advances in the synthesis and applications of furan moiety using silver catalysis and covers literature from 2015-2020.

Lack of environmental sustainability is a growing and pivotal matter due to the issues such as disturbances associated with biodiversity pollution and climate change. Pollutants are the major cause of these environmental threats in the atmosphere. At present, nano-based photocatalysts are at the forefront of the author's interest because of their promising potential as a green chemical-based compound, high catalytic activity, suitable and controllable surface area for wastewater treatment. Semiconductor materials on a nano-sized scale have electronic and optical properties depending on their building block size, which plays a vital role in developing smart materials that are well-efficient for simultaneously destroying harmful chemical contaminants from our environment. This makes these materials useful in many possible industrial applications, such as water purification. In this review, we have reported the most significant results contributing to the progress in the area of environmental hazardous pollutant detection and removal focused on water purification especially through photocatalysis to give readers an overview of the present research trends. Moreover, we have analyzed previous studies to indicate key principles of photocatalysis and provide guidelines that can be used to fabricate more efficient photocatalysts.

The influence of air–calcination (500oC for 2h) on the physicochemical properties of natural mordenite and mordenite activated by aqueous solutions of several acids, has been studied through various methods. Calcination does not affect the crystal structure of the samples and their fibrous and pores morphology. In contrast, it causes a drastic decrease in the high Bronsted acidity of the acidactivated samples, which was tentatively attributed to the partial destruction of the very strong Al– (OH)–Si acid sites. The influence of calcination on the texture is different depending on the acidic solution used for mordenite activation. The high specific surface area and the moderate acidity obtained after calcination of the sample activated by HCl render this material quite attractive support for the development of nickel supported catalysts for green diesel production.

Background: Hydrogen peroxide is normally formed during the metabolic pathway of the body. It is a toxic compound for vital cells, which can oxidize many macromolecules and cause damage in cells. Catalase can degrade H2O2 in cells and prevent cell injury. Cimetidine is a histamine H2 receptor blocker which decreases the release of stomach acid and is used for gastrointestinal diseases. Cimetidine inhibited catalase by mixed inhibition. Objective: In this study, the effect of temperature on the binding of cimetidine to human erythrocyte catalase was investigated and kinetic factors of the binding were determined. Results: Dixon plot confirmed the mixed type of inhibition and determined the Ki of the drug. The maximum activity of the enzyme was observed at 30°C. Arrhenius plot demonstrated that the activation energy of the enzyme reaction in the absence and presence of cimetidine was about 4.7 and 8.13 kJ/mol, respectively. The temperature coefficient (Q3040) was determined as about 1.11 and 1.09 in the absence and presence of cimetidine. Conclusion: Cimetidine was able to increase the activation energy of the reaction of catalase, which confirmed the inhibition of the enzyme based on the kinetic results.

Background: Increased environmental protection concerns urge more effort to develop new catalysts for the abetment of greenhouse gases. N2O is known as a powerful greenhouse gas. The literature review revealed that various catalysts have been developed for the direct decomposition of N2O. Special attention was given to the cobalt-based spinel oxides. However, there is a lack of information about the performance of the cadmium promoted spinels for N2O abetment. Objective: This paper addresses the nitrous oxide direct decomposition over a novel series of Cd- Co catalysts. Method: These catalysts, with Cd/(Cd + Co) ratios 0.00-0.333, were prepared with the aid of the co-precipitation route, which is followed by calcination at 500 °C. Characterization of these catalysts was performed employing TGA-DTA, XRD, FTIR, N2O adsorption/desorption, and atomic absorption spectrophotometry. Results: Phase analysis revealed the absence of a solid-state interaction between CdO and Co3O4. However, it was found that increasing the Cd/(Cd + Co) ratio is associated with continuous enhancement of the N2O decomposition activity. The activity was correlated with the presence of catalyst's redox couples. Moreover, the role of the Cd presence in improving the activity was discussed. Finally, the activity performance change accompanying the calcination temperature raise was also investigated. Conclusions: Presence of cadmium has a positive effect on the N2O decomposition performance of Co3O4. Activity increased continuously with Cd/(Cd + Co) ratio increase over the examined range 0.083–0.333 structural, textural, and electronic roles of cadmium were proposed.