Catalysts for Heterogeneous Photocatalysis. Part 2. Methods for Synthesis (original) (raw)

Heterogeneous photocatalysis from fundamentals to possible applications

Catalysis Today, 2017

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HETEROGENEOUS PHOTOCATALYSIS - A REVIEW

A variety of conventional methods are available to meet our present energy demands. But as the world is witnessing tremendous developments in all areas of life, as such the conventional methods are no longer sufficient to meet our ever growing demands. A dvanced oxidation processes (AOP) render great future for energy conversion and environmental issues like fuel generation, air and water detoxification, environmental cleanup etc. In view of the utilization of solar energy and AOPs, many applications like photovoltaic cells, solar cells, fuel production, organic synthesis, photo catalysis and many more has been studied in the last few decades. Out of these many applications of solar energy, this review paper focuses on Heterogeneous Photo catalysis. In this review, draw backs of conventional treatment methods, Advantages of AOPs in contrast to conventional methods, basic principle, working mechanism and applications of photocatalysis are discussed.

Heterogeneous photocatalytic organic synthesis: state-of-the-art and future perspectives

Green Chemistry, 2016

Heterogeneous photocatalytic systems have the potential to provide a green organic synthesis route for a number of industrially important chemicals. Issues remain with lack of selectivity. In this paper, a review is presented on achievements in this field. Parallels are drawn between systems optimised for heterogeneous photocatalytic organic degradation and heterogeneous catalytic organic synthesis. There is much fundamental knowledge that is still missing in this field of research. Parameters that can be manipulated are reaction solvent, pH, photon energy, chosen photocatalyst and its specific properties, and perhaps the use of more than one photocatalyst. Screening of photocatalysts for specific reactions and adapting the reaction conditions may achieve the best selectivity. Unlike the popular case of photocatalysts for organic degradation, the photocatalysts for organic synthesis should be highly customised on a case-by-case basis. Attention should be given to photocatalysts with the potential to be activated by the visible light spectrum, in order to achieve cost effectiveness of the heterogeneous photocatalytic organic synthesis.

Advances in selective conversions by heterogeneous photocatalysis

Chemical …, 2010

Selective photocatalytic conversions are offering an alternative green route for replacing environmentally hazardous processes with safe and energy efficient routes. This paper reports the most recent advances in the application of heterogeneous photocatalysis to synthesize valuable compounds by selective oxidation and reduction.

ChemInform Abstract: The Past, Present and Future of Heterogeneous Catalysis

ChemInform, 2012

This review highlights key catalytic discoveries and the main industrial catalytic processes over the last 300 years that involved commodities, fine chemicals, petrochemicals, petroleum transformation for fuels and energy supply, emission control, and so forth. In the past, discoveries have often followed events such as wars or embargos, whereas the current driving forces of studies, researches and then discoveries aim at a better understanding of catalytic processes, at reducing the costs of raw materials and processes, at developing new catalytic materials and at addressing environmental issues. This review focuses on the history of many catalytic industrial processes, environmental issues, catalytic materials, especially their expected catalytic properties, on catalyst characterisation by physical methods and development of in situ conditions, i.e., characterisation under actual working conditions with reactants and products analyzed on-line. Emphasis is also placed on high selectivity in catalytic reactions and the major challenges for the future, such as environmental issues, energy supply, pollution control for vehicles and industrial plants, air/VOCs/water purification, hydrogen sources and carbon dioxide storage/up grading, transformation of biomass as a promising source of raw materials, and catalytic water splitting perspectives. This review is a survey of heterogeneous catalysis and is not comprehensive but leads to the conclusion that, although many catalysts and catalytic processes have already been discovered and developed over the past century, many opportunities nevertheless exist for new developments, new processes and new catalytic materials. It follows that substantial challenges exist for the younger generation of researchers and engineers, as emphasized at the end of the manuscript.

Photocatalysis—A Special Issue on a Unique Hybrid Area of Catalysis

Catalysts, 2012

Where is photocatalysis situated in the broad field of catalysis? Photocatalysis is a term that combines the basic notion of a catalyst as a material that enhances the rate as a reaction approaches equilibrium without being consumed with the notion that the reaction is accelerated by photons, which of course are consumed. Thus, it is a hybrid concept. As with other areas of catalysis, it has its heterogeneous and its homogeneous dimensions with the former dominating the research literature. Nevertheless, the homogeneous opportunities should not be overlooked. A typical example of a homogeneous case can be found with a dye photocatalyst having two oxidation states where one state can achieve an electron transfer after excitation by light, where that reaction is not feasible from the ground state. If the resulting oxidation state is thermally or photochemically unstable, a catalytic cycle can be completed. Some non-dye examples of homogeneous photocatalysts include soluble ions with multiple oxidation states, including at least one readily excitable by light, such as the polyoxometallates of tungsten or Fenton's reagent. Although photochemists prefer the term "sensitizer", excited states that transfer energy to a molecule that then reacts can be viewed as photocatalysts.