Overview of Photocatalytic Membrane Reactors in Organic Synthesis, Energy Storage and Environmental Applications

Abstract

This paper presents an overview of recent reports on photocatalytic membrane reactors (PMRs) in organic synthesis as well as water and wastewater treatment. A brief introduction to slurry PMRs and the systems equipped with photocatalytic membranes (PMs) is given. The methods of PM production are also presented. Moreover, the process parameters affecting the performance of PMRs are characterized. The applications of PMRs in organic synthesis are discussed, including photocatalytic conversion of CO2, synthesis of KA oil by photocatalytic oxidation, conversion of acetophenone to phenylethanol, synthesis of vanillin and phenol, as well as hydrogen production. Furthermore, the configurations and applications of PMRs for removal of organic contaminants from model solutions, natural water and municipal or industrial wastewater are described. It was concluded that PMRs represent a promising green technology; however, before the application in industry, additional studies are still required. These should be aimed at improvement of process efficiency, mainly by development and application of visible light active photocatalysts and novel membranes resistant to the harsh conditions prevailing in these systems.

Main parameters influencing the design of photocatalytic reactors for wastewater treatment: a mini review

“…Considering the previous observations, it is clear that the choice of radiation source must be made by considering that the energy associated with the radiation emitted by light sources should be equal to or higher than the band gap of the selected photocatalyst. Other important parameters that affect the photoreactor performance are: (i) the mode of operation; (ii) the phases present in the reactor; (iii) the hydrodynamic behavior; and (iv) the composition and the operative conditions of the reacting mixture 55 …”

Process intensification technologies for CO2 capture and conversion – a review

“…The membrane is characterised by high level of compactness, ability to address thermodynamic limitations [156], high contact area [157] owing to drastic reduction in the size of the unit [158] at the expense however of generally high membrane cost. This technology has been employed for carbon capture [159], in photochemical [160,161], electrochemical [162], and thermochemical [82] CO 2 conversion processes aiming to overcome mass transfer resistance and enhance energy efficiency. With multifunctional units such as these membrane-integrated reactors, combining two functions into one unit should reduce the capital cost of the single unit compared to the individual reactor and membrane separation unit [163].…”

Hydrogen Production and Organic Synthesis in Photocatalytic Membrane Reactors: A Review

“…Among the most sustainable methods for hydrogen production, today the water splitting by using solar energy is a very challenging approach. Photocatalytic water splitting is an important pathway for producing hydrogen, which is a promising alternative source of clean and renewable energy [28][29][30][31][32][33]. To achieve high hydrogen conversion efficiency under solar irradiation, various kinds of photocatalysts have been developed through reasonable engineering strategies.…”

“…Membrane reactors technology represents a promising tool for the CO 2 capture and reuse by conversion to valuable products. The reuse of emitted CO 2 as a raw feedstock to promote energy bearing products is attracting considerable attention [33,[53][54][55][56][57].…”

“…Below the state of the art of few papers present in literature in the last years is reported. Considering that traditional industrial processes employed for the synthesis of organic substances are becoming unsustainable in terms of resources and environmental impact, in the last years the application of photocatalytic reactions to organic synthesis has attracted high interest [4,25,33,60,[80][81][82][83]].…”