Photocatalytic reduction of CO 2 with H 2 O over graphene oxide-supported oxygen-rich TiO 2 hybrid photocatalyst under visible light irradiation: Process and kinetic studies

Tan, Lling‐Lling; Ong, Wee‐Jun; Chai, Siang‐Piao; Mohamed, Abdul Rahman

doi:10.1016/j.cej.2016.09.050

Cited by 141 publications

(70 citation statements)

References 77 publications

(84 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…CO 2 is a relatively inert species that must be activated before it can react. Activation can be accomplished by photocatalysis, electrochemistry, raising the gas to high temperature, or using low temperature plasma, which is a partially ionized gas. Of these activation methods, plasma has a combination of desirable traits that stands out from the others: high‐energy efficiency (up to 90%), high reaction rates at the laboratory scale (approximately 1 t m −3 hr −1 ), and the possibility of low background gas temperature for compatibility with temperature‐sensitive molecules.…”

Section: Introductionmentioning

confidence: 99%

Superlocal chemical reaction equilibrium in low temperature plasma

Üner

Thimsen

2020

AIChE Journal

View full text Add to dashboard Cite

Low temperature plasmas (LTP) are a unique class of open-driven systems in which chemical reactions are unpredictable using established concepts. The terminal state of chemical reactions in LTP, termed the superlocal equilibrium state, is hypothesized to be defined by a proposed set of state variables. Using a LTP reactor wherein the state variables have been measured, it is shown that CO 2 spontaneously splits and the effluent speciation is independent of the influent speciation if the state variables are held constant and the residence time is long. CO 2 conversion at long residence times, which is expected to be nominally zero from equilibrium thermodynamics, can be as high as 70% in the LTP. The employed low pressure plasma reactor (P = 10 mbar) had a similar volume, productivity, and energy efficiency compared to an atmospheric pressure dielectric barrier discharge reactor, thanks to reaction rates that were three orders of magnitude faster. K E Y W O R D SCO 2 splitting, low-pressure reactor, low-temperature plasma, plasma chemistry, superlocal equilibrium 1 | INTRODUCTION A major challenge currently facing chemical engineering is the development of processes to transform CO 2 into platform chemicals from which valuable materials can be synthesized, with the goal of removing the greenhouse gas from the atmosphere. CO 2 is a relatively inert species that must be activated before it can react. Activation can be accomplished by photocatalysis, 1-3 electrochemistry, 4-7 raising the gas to high temperature, 8 or using low temperature plasma, [9][10][11] which is a partially ionized gas. Of these activation methods, plasma has a combination of desirable traits that stands out from the others: high-energy efficiency 12 (up to 90%), high reaction rates at the laboratory scale (approximately 1 t m −3 hr −1 ), and the possibility of low background gas temperature for compatibility with temperature-sensitive molecules. The synthesis of platform chemicals from CO 2 will likely require sophisticated reaction engineering. A major challenge preventing engineering of reactions between CO 2 and other molecules such as CH 4 or H 2 O in low temperature plasma is that one cannot make the local equilibrium assumption, 13 and consequently, practical methods to predict the direction and maximum extent of chemical reactions have not been forthcoming.The concept of thermodynamic equilibrium is generally used to predict the direction of chemical reactions and theoretical maxima for conversion and yield. In flow systems, which are intrinsically not at equilibrium, 14 the local equilibrium assumption 15 is often used for process modeling. One aspect of the local equilibrium assumption is that at given location in space, one can describe a single temperature, which is defined as T = ∂U ∂S À Á x , where U is internal energy, S is entropy, and the partial derivative is taken at constant work displacement x. Nonequilibrium systems can then be modeled using temperature gradients and the associated heat fluxes. 16 Such approaches for modeli...

show abstract

Section: Introductionmentioning

confidence: 99%

Superlocal chemical reaction equilibrium in low temperature plasma

Üner

Thimsen

2020

AIChE Journal

View full text Add to dashboard Cite

show abstract

“…The technologies used to reduce the CO 2 concentration are energy consuming and expensive [36–37]. In recent years, semiconductor-based visible-light-induced photocatalytic reduction of CO 2 has emerged as an attractive and viable approach for not only decreasing the concentration of atmospheric CO 2 but also producing energy fuels such as CH 4 [53].…”

Section: Reviewmentioning

confidence: 99%

“…This process involves: (i) generation of renewable energy such as H 2 and O 2 by photoelectrochemical water splitting [30–32], (ii) photocatalytic CO 2 conversion [33–37], (iii) photocatalytic nitrogen (N 2 ) fixation [38], (iv) selective organic transformation for the ﬁne chemical synthesis [39–42] and (v) photodegradation of pollutants [43–49]. Semiconductor-based photocatalysis proceeds through following three steps: (1) absorption of light; (2) separation and transport of charge carriers; and (3) redox reactions on the surface of the semiconductor.…”

Section: Introductionmentioning

confidence: 99%

Cr(VI) remediation from aqueous environment through modified-TiO₂-mediated photocatalytic reduction

Acharya

Naik

Parida

2018

Beilstein J. Nanotechnol.

102

View full text Add to dashboard Cite

Cr(VI) exhibits cytotoxic, mutagenic and carcinogenic properties; hence, effluents containing Cr(VI) from various industrial processes pose threat to aquatic life and downstream users. Various treatment techniques, such as chemical reduction, ion exchange, bacterial degradation, adsorption and photocatalysis, have been exploited for remediation of Cr(VI) from wastewater. Among these, photocatalysis has recently gained considerable attention. The applications of photocatalysis, such as water splitting, CO2 reduction, pollutant degradation, organic transformation reactions, N2 fixation, etc., towards solving the energy crisis and environmental issues are briefly discussed in the Introduction of this review. The advantages of TiO2 as a photocatalyst and the importance of its modification for photocatalytic reduction of Cr(VI) has also been addressed. In this review, the photocatalytic activity of TiO2 after modification with carbon-based advanced materials, metal oxides, metal sulfides and noble metals towards reduction of Cr(VI) was evaluated and compared with that of bare TiO2. The photoactivity of dye-sensitized TiO2 for reduction of Cr(VI) was also discussed. The mechanism for enhanced photocatalytic activity was highlighted and attributed to the resultant properties, namely, effective separation of photoinduced charge carriers, extension of the light absorption range and intensity, increase of the surface active sites, and higher photostability. Advantages and limitations for photoreduction of Cr(VI) over modified TiO2 are depicted in the Conclusion. The various challenges that restrict the technology from practical applications in remediation of Cr(VI) from wastewater were addressed in the Conclusion section as well. The future perspectives of the field presented in this review are focused on the development of whole-solar-spectrum responsive, TiO2-coupled photocatalysts which provide efficient photocatalytic reduction of Cr(VI) along with their good recoverability and recyclability.

show abstract

“…Therefore it is possible to obtain similar results minimising the primary energy input. [73,74], while Tan and co-workers reported a miximum 3.14 μmol gcat −1 after eight hour reactions with graphene oxide-modified TiO2 [75], and Ola and Maroto-Valer reached 4.87 μmol gcat −1 by means of a V-TiO2 photocatalyst [76]. Compared to cited works, reaction conditions here are considerably milder, particularly in terms of irradiance; in fact, they are in cited paper irradiance ranges from 500 to 3000 W•m −2 , whilst here irradiance is 50 W•m −2 .…”

Section: On the Reactor Designmentioning

confidence: 99%

Sustainable Carbon Dioxide Photoreduction by a Cooperative Effect of Reactor Design and Titania Metal Promotion

et al. 2018

View full text Add to dashboard Cite

An effective process based on the photocatalytic reduction of CO 2 to face on the one hand, the crucial problem of environmental pollution, and, on the other hand, to propose an efficient way to product clean and sustainable energy sources has been developed in this work. Particular attention has been paid to the sustainability of the process by using a green reductant (water) and TiO 2 as a photocatalyst under very mild operative conditions (room temperature and atmospheric pressure). It was shown that the efficiency in carbon dioxide photoreduction is strictly related to the process parameters and to the catalyst features. In order to formulate a versatile and high performing catalyst, TiO 2 was modified by oxide or metal species. Copper (in the oxide CuO form) or gold (as nanoparticles) were employed as promoting metal. Both photocatalytic activity and selectivity displayed by CuO-TiO 2 and Au-TiO 2 were compared, and it was found that the nature of the promoter (either Au or CuO) shifts the selectivity of the process towards two strategic products: CH 4 or H 2 . The catalytic results were discussed in depth and correlated with the physicochemical features of the photocatalysts.

show abstract

Photocatalytic reduction of CO 2 with H 2 O over graphene oxide-supported oxygen-rich TiO 2 hybrid photocatalyst under visible light irradiation: Process and kinetic studies

Cited by 141 publications

References 77 publications

Superlocal chemical reaction equilibrium in low temperature plasma

Superlocal chemical reaction equilibrium in low temperature plasma

Cr(VI) remediation from aqueous environment through modified-TiO₂-mediated photocatalytic reduction

Sustainable Carbon Dioxide Photoreduction by a Cooperative Effect of Reactor Design and Titania Metal Promotion

Contact Info

Product

Resources

About

Photocatalytic reduction of CO 2 with H 2 O over graphene oxide-supported oxygen-rich TiO 2 hybrid photocatalyst under visible light irradiation: Process and kinetic studies

Cited by 141 publications

References 77 publications

Superlocal chemical reaction equilibrium in low temperature plasma

Superlocal chemical reaction equilibrium in low temperature plasma

Cr(VI) remediation from aqueous environment through modified-TiO2-mediated photocatalytic reduction

Sustainable Carbon Dioxide Photoreduction by a Cooperative Effect of Reactor Design and Titania Metal Promotion

Contact Info

Product

Resources

About

Cr(VI) remediation from aqueous environment through modified-TiO₂-mediated photocatalytic reduction