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Photocatalytic CO2 conversion to hydrocarbon products is an appealing strategy for solving the escalating problem of energy scarcity and global warming. Although there has been much research to date, most of it has been aimed at increasing yields rather than product selectivity. However, regulating product selectivity is vital to achieve controlled hydrocarbon products. Particularly, the C2+ products have a higher added value than C1 products (e.g., methane, carbon monoxide, methanol), so it makes more economic sense to increase the selectivity of C2+ products. This review provides a concise overview of the latest developments in the photocatalytic conversion of CO2 into multi-carbon compounds. The available literature has been organized according to the primary factors that determine the selectivity of C2+ products, including vacancy engineering, co-catalyst loading, doping engineering, and surface plasmon resonance effect. Plausible conjectures concerning methods to enhance the selectivity of C2+ products have been presented, with a focus on synthesizing the existing empirical knowledge derived from theoretical and experimental data. [ABSTRACT FROM AUTHOR]

The power sector has been the industry that generates the most carbon emissions in China, with its share of emissions reaching 50% at its peak, causing serious environmental problems. Therefore, the power sector is the core and key part to achieve the overall national goal of reducing emissions. In this study, the Undesirable-SBM (Slack-Based Measure) model was used to assess the carbon emission efficiency of the thermal power sector in China by province in the period from 2010 to 2019. Further, the index decomposition is carried out based on the construction of the global carbon emission efficiency index in conjunction with the Malmquist index, and the causes and sensitivities of carbon emission efficiency changes are explored by technical efficiency changes and technical progress changes. Finally, the spatial correlation of carbon emission efficiency in thermal power industry is diagnosed by combining Moran index. The results show that the overall average carbon emission efficiency of China's provincial thermal power industry is low, with some regional differences, showing a decreasing order of east-west and central regions, and the carbon emission efficiency of thermal power industry has significant spatial correlation between regions, with positive spillover effects on neighboring provinces, and strengthening over time. The carbon emission efficiency itself is lower in the central and western regions, and it is easier to achieve a larger improvement, and the positive impact of technological changes on efficiency changes is stronger. Therefore, inter-regional technical cooperation can help improve carbon efficiency. [ABSTRACT FROM AUTHOR]

Effectively harnessing solar energy for the conversion of CO2 into valuable chemical energy presents a viable solution to address energy scarcity and climate change concerns. Nonetheless, the limited light absorption and sluggish charge kinetics significantly hinder the photoreduction of CO2. In this study, we employed a facile sol–gel method combined with wetness impregnation to synthesize Cu-doped TiO2 coated with NiOx nanoparticles. Various characterizations verified the successful incorporation of Cu ions into the TiO2 crystal lattice and the formation of NiOx co-catalysts within the composites. The optimal performance attained with CTN-0.5 demonstrates an output of 11.85 μmol h−1 g−1 for CO and 9.51 μmol h−1 g−1 for CH4, which represent a 4.4-fold and 15.6-fold increase, respectively, compared to those achieved with pure TiO2. The induced Cu defect band broadens the light absorption by decreasing the conduction band edge of TiO2, while NiOx upshifts the valence band of TiO2 because of the interaction of valence orbitals. Light irradiation EPR and FTIR tests suggest that the collaboration of CuOx and NiOx promotes the formation of oxygen vacancies/defects and a rapid charge transfer pathway, thereby provides numerous active sites and electrons to enhance CO2 photoreduction performance. [ABSTRACT FROM AUTHOR]

In this research, a ternary Cu-CuTCPP/Cu2O/CoAl-LDH composite with a dual Z-scheme heterostructure was fabricated based on a Cu2O photocatalyst and applied in photocatalytic CO2 reduction. The physicochemical properties of the prepared catalysts and the possible reaction mechanism in CO2 reduction were analyzed and studied by various characterization methods. The activity of CO2 reduction significantly increased, especially forming C2 products. The optimal yield of C2H4 and C2H6 reached 1.56 and 1.92 μmol g−1 h−1 respectively, which was 14.45 and 17.45 times that from using the Cu2O monomer. In addition, the selectivity of C2 products reached 37.4%. The satisfactory C2 yield was mainly due to the fact that Cu1+δ2(COO)3 nodes in Cu-CuTCPP contained adjacent Cu sites, which effectively promoted the C–C coupling reaction. Moreover, the dual Z-scheme heterojunction stimulated the separation of photogenerated electron–hole pairs and diminished the recombination rate. This work contributes to the development of novel photocatalysts with a dual Z-scheme heterojunction and facilitates the generation of valuable C2 products. [ABSTRACT FROM AUTHOR]

Energy shortage and global warming caused by the extensive use of fossil fuels are urgent problems to be solved at present. Photoreduction of CO2 is considered to be a feasible solution. The ternary composite catalyst g‐C3N4/Ti3C2/MoSe2 was synthesized by hydrothermal method, and its physical and chemical properties were studied by an array of characterization and tests. In addition, the photocatalytic performance of this series of catalysts under full spectrum irradiation was also tested. It is found that the CTM‐5 sample has the best photocatalytic activity, and the yields of CO and CH4 are 29.87 and 17.94 μmol g−1 h−1, respectively. This can be ascribed to the favorable optical absorption performance of the composite catalyst in the full spectrum and the establishment of S‐scheme charge transfer channel. The formation of heterojunctions can effectively promote charge transfer. The addition of Ti3C2 materials provides plentiful active sites for CO2 reaction, and its superior electrical conductivity is also favorable for the migration of photogenerated electrons. [ABSTRACT FROM AUTHOR]

The photocatalytic reduction of CO2 to hydrocarbons is expected to simultaneously alleviate the energy crisis and greenhouse effect. Herein, the ternary BiOCl/C/Cu2O catalysts with different mass ratios were compounded using a simple hydrothermal method, revealing better photocatalytic activity than the monomer. In the absence of sacrificial agents and photosensitizers, 25% BiOCl/C/Cu2O showed optimal photocatalytic performance. The CO and CH4 yields over 25% BiOCl/C/Cu2O reached 26.77 and 9.86 μmol g−1 h−1, which is 2.9 and 8.7 times higher than that of the pristine Cu2O, respectively. The ameliorative activity can be attributed to the construction of the Z-scheme heterostructure and carbon layer, which are conducive to the transfer and separation of photogenerated carriers. This study offers valuable references for the design and investigation of a Z-scheme heterojunction using a carbon layer as an electron transfer medium. [ABSTRACT FROM AUTHOR]

Herein, the origin and evolution mechanism of N2O formation over the MnFeOx spherical catalyst were investigated in detail, accompanied by a comparison analysis of pristine MnOx and FeOx catalysts. The results showed that the MnFeOx catalyst possessed higher catalytic activity but poorer N2 selectivity than the sole oxide catalysts, and the N2O concentration could even reach 300 ppm over 175 °C. Further activation tests under separate NH3/NO oxidation conditions revealed the N2O accumulation of the MnFeOx catalyst that was primarily derived from the NSCR pathway below 150 °C and then gradually turned to NH3 over-oxidation with temperature. The coupling of Mn and Fe cations induced electron migration and released more Mn4+ and Os, contributing to the upgraded redox capacity, which served as the inherent motivation of high activity but poor N2 selectivity over the MnFeOx catalyst. For the NH3 over-oxidation pathway, both gaseous O and catalyst oxygen acted as the oxidizers, and the double –NH2/NH species with the assistance of O was deemed as the restricted step for N2O generation. For the NSCR pathway, the byproduct N2O was generated through both E–R and L–H mechanisms, and the former contributed to more N2O. In addition, the kinetic analysis further verified the obtained conclusions. Finally, a possible mechanism model of N2O origins over the MnFeOx catalyst was proposed. [ABSTRACT FROM AUTHOR]

In recent years, heterojunction materials bonded by interlayer van der Waals forces have grown into a very large family. These van der Waals heterostructures have promising applications in photocatalysis due to their suitable energy band structures and optical properties. In this paper, the latest research progress on van der Waals heterojunction materials in photocatalytic systems is reviewed, including the photocatalytic theories and the basic principles of heterojunctions in photocatalysis. The construction, design, and photocatalytic properties and applications of van der Waals heterostructures are described in detail. The prospects and challenges of van der Waals heterojunctions in photocatalytic applications in the future are also presented. This review is intended to offer enlightening guidance for the efficient use of solar energy systems, efficient photocatalysis and early industrialization in the future. [ABSTRACT FROM AUTHOR]

Selective catalytic reduction with NH3 (NH3-SCR) was the most efficient approach to mitigate the emission of nitrogen oxides (NOx). Although the conventional manganese oxide-based catalyst had gradually become a kind of principal catalyst for the low-temperature NH3-SCR reaction, there were still numerous defects. The growing demands for extensive operation temperature scope, strong SO2 tolerance, and excellent catalytic activity had boosted the development of novel manganese oxide-based catalysts. In this review, three forms of manganese oxide-based catalysts were introduced in detail, including single manganese oxide catalysts, composite manganese oxide-based catalysts, and supported manganese oxide-based catalysts. The surface acidity and redox properties of manganese oxide-based catalysts could be strengthened by optimizing the preparation methods, exposing specific crystal planes, and constructing multiple active centers and sacrificial sites, which improved the SCR performance and anti-poisoning properties of catalysts. Secondly, we briefly summarized the NH3-SCR reaction mechanism of manganese oxide-based catalysts, including the Eley–Rideal (E–R) mechanism and the Langmuir–Hinshelwood (L–H) mechanism. Finally, several overtures were proposed for the future research directions of manganese oxide-based catalysts for NH3-SCR reaction, hoping to narrow the gap between the novel manganese oxide-based catalysts and the actual demands and realize commercialized application in the nearest future. [ABSTRACT FROM AUTHOR]

Graphite carbon nitride (g‐C3N4), as a non‐metallic photocatalyst, possesses special band structure, excellent stability and unique surface properties, which has become a focus of attention for photocatalytic application. However, pure g‐C3N4 is subject to the limit of visible light response, small specific surface area and rapid recombination of photogenerated carriers, which leads to its low photocatalytic efficiency. Due to the unique electronic structure, various quantum dots (QDs) can be applied to modify g‐C3N4 to improve the photocatalytic activity. Thus, we highlight these QDs modified g‐C3N4‐based composites by emphasizing their synthesis, their physicochemical properties as well as their photocatalytic applications in CO2 reduction, hydrogen production and pollutants degradation in this review. At last, critical summaries and some perspectives on the challenges and directions in this research field are also presented. [ABSTRACT FROM AUTHOR]

Promoting the separation of photogenerated electron–hole pairs and enhancing the charge carrier transfer are critical in photocatalysis. In our work, a ball-flower-like NiS/Zn3In2S6/g-C3N4 photocatalyst fabricated by a hydrothermal method exhibited superior performance for photocatalytic water splitting. The optimized 2.0% NiS/Zn3In2S6/g-C3N4 rivaled noble metal based Pt/g-C3N4 and showed an apparent quantum efficiency (AQE) of 24.3% at 420 nm, with a H2 yield of 4.135 mmol g−1 h−1, which was 30.4 and 9.51 times that of pure g-C3N4 and binary Zn3In2S6/g-C3N4 composites, respectively. The experimental and characterization results suggested that the heterojunction formed between Zn3In2S6/g-C3N4 and the decorating NiS co-catalyst cooperatively suppressed the electron–hole recombination and facilitated the charge carrier transfer, thus resulting in significant improvement of the H2 evolution performance. Moreover, the increased specific surface area and the enhanced visible-light absorption also contributed to superior water splitting performance. The prepared ternary catalytic system with the heterojunction and non-noble metal co-catalyst has great potential as an alternative to noble metals for achieving cost-efficient water splitting systems. [ABSTRACT FROM AUTHOR]

The effect of CaO-MgCO3 additives on the combustion property of semi-coke (SC) was investigated using thermogravimetric analysis. Based on the experimental results, the addition of CaO (Ca/S = 2) on SC could reduce the ignition temperature (about 1.3 °C) and burnout temperature (about 0.99 °C). Besides, the additive of CaO on SC had significantly decreased the emissions of SO2 and NOx. However, the addition of 1 wt% MgCO3 on SC-CaO could promote the burning process and remarkably reduce the ignition temperature (about 10 °C) and burnout temperature (about 8.64 °C). Moreover, the smallest activation energy was available for the combustion of SC-CaO-1 wt% MgCO3. On the other hand, the addition of MgCO3 with different content (0.5 wt%, 1 wt%, 2 wt%, 4 wt%) on SC-CaO could enhance the pore size of CaO, promote the sulfur fixation performance. Comparing with other SC-CaO-MgCO3 samples, the addition of appropriate amount of MgCO3 (1 wt%) could effectively promote the catalytic desulfuration and denitrification of CaO. Therefore, CaO-1 wt% MgCO3 could effectively inhibit SO2 and NOx emission, which had great potential to be an efficient and clean method for the large-scale utilization of semi-coke. [ABSTRACT FROM AUTHOR]

In this study, a remarkable offset deactivation effect of K and P on MnEuOx SCR catalyst has been found. Experimental results showed that the NO conversion over K−P poisoned catalyst was close to 80 % at 250 °C. Several characterization techniques containing NH3‐TPD, XPS, H2‐TPR, XRD and in situ DRIFT were used to reveal the mechanism of the offset effect. The characterization of NH3‐TPD and H2‐TPR suggested that the introduction of P on MnEuOx‐K could improve its surface acidity and redox ability. Moreover, the content of chemisorbed oxygen and Mn4+ were markedly restored under the situation that the toxic elements were coexistent on catalyst surface. The strong interaction between K and P might be the major reason for the offset deactivation effect. More specifically, PO3− species were preferentially bonded with the surface potassium species and released MnO2 active sites poisoned by K. Therefore, the highly active MnO2 sites might be protected and the catalytic activity could be restored. [ABSTRACT FROM AUTHOR]

A series of Sb-doped CeVO 4 samples were synthetized by hydrothermal method and used in selective catalytic reduction of NO with NH 3. Contrasted with other catalysts, Sb 2 CeVO 4 possessed superior NH 3 -SCR activity and excellent SO 2 tolerance. Besides, the characterization results testified that Sb species in Sb 2 CeVO 4 could reduce the crystallization of CeVO 4 , and improve the surface acidity and reducibility. Moreover, the existence of Sb3+ was beneficial to generate more surface adsorbed oxygen species. Based on the in situ DRIFT spectra, more ad-NH 3 and ad-NO x species with higher reactivity were obtainable on Sb 2 CeVO 4 catalyst compared with that on CeVO 4 catalyst, which also contributed to enhancing the SCR activity by Langmuir-Hinshelwood (L-H) mechanism effectively. Image 1 • Sb modification could improve the SCR performance of CeVO 4 catalyst. • Sb3+ was beneficial to generate more surface adsorbed oxygen species. • More active ad-NH 3 and ad-NO x species were available on Sb 2 CeVO 4 catalyst. [ABSTRACT FROM AUTHOR]

Considering the high charge recombination rate, low optical adsorption intensity and limited active sites greatly constrict the solar‐to‐chemical conversion efficiency of polymer carbon nitride. Herein, a facile approach is reported to produce defected polymeric carbon nitride (PCN) with abundant granular bulks with fractured boundaries by thermal reduction treatment in CO atmosphere. The photocatalytic hydrogen evolution over defected PCN exhibits a rate of 3281.2 μmol g−1 h−1, 3.5 times higher than the pristine, which is most possibly ascribed to the following factors. The unique defected and porous structure not only provides higher specific surface area, more exposed active edges, abundant charge separation sites, and active centers for hydrogen generation but also is beneficial to rapid mass and charge transfer, interior diffusing of incident light, and shortening carrier transport length, thus enhancing the optical adsorption and accelerating the photocatalytic reaction kinetics. Furthermore, the electron delocalization at carbon vacancies sites on one hand facilitates the separation rate of electron–hole pairs and prolonged the carrier lifetime; on the other hand, the electronic polarization caused by C atoms loss helps increasing the affinity between catalyst and substrate reactant. Moreover, the higher electron donor density and lower conduction band minimum (CBM) potential further enhance the reduction capacity for H2 evolution. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen evolution can effectively alleviate the troublesome global energy crisis by converting solar energy into the chemical energy of hydrogen. In order to realize efficient hydrogen generation, a variety of semiconductor materials have been extensively investigated, including TiO2, CdS, g‐C3N4, metal‐organic frameworks (MOFs), and others. In recent years, to achieve higher photocatalytic performance and reach the level of large‐scale industrial applications, photocatalysts decorated with transition metal phosphides (TMPs) have shone brightly because of their low cost, stable physical and chemical properties, and substitution for precious metals of TMPs. This Review highlights the preparation methods and properties associated with photocatalysis of TMPs. Moreover, the H2 generation efficiency of photocatalysts loaded with TMPs and the roles of TMPs in catalytic systems are also studied systematically. Apart from being co‐catalysts, several TMPs can also serve as host catalysts to boost the activity of photocatalytic composites. Finally, the development prospects and challenges of TMPs are put forward, which is valuable for future researchers to expand the application of TMPs in photocatalytic directions and to develop more active photocatalytic systems. [ABSTRACT FROM AUTHOR]

The Cu/TiO2 catalysts with the addition of Eu were developed by the sol-gel way for the selective catalytic reduction (SCR) of NOx by NH3. Activity tests revealed that CuEu/TiO2-0.15 catalyst showed the optimal de-NOx performance in a wide temperature range (150–300 °C), along with an admirable SO2 tolerance. According to characterization analysis, the relationship between the NH3-SCR performance and physicochemical characters of samples was explored. The adjunction of Eu on Cu/TiO2 catalyst can contribute to the formation of a large amount of Cu2+, adsorbed oxygen, and acid sites on the catalyst surface. Moreover, the Eu addition on Cu/TiO2 is favorable to the generation of activated NOx and NH3 substances adsorbed on the catalyst surface, which would conduce to the NH3-SCR process by Langmuir-Hinshelwood (L-H) mechanism effectively. [ABSTRACT FROM AUTHOR]

In this study, it was found that the CeVO4-CeO2 nanocomposite possessed remarkably selective catalytic reduction (SCR) performance and wider active temperature scope. And, the promotion principle was explored based on BET, XRD, XPS, H2-temperature-programmed reduction, NH3-temperature-programmed desorption, and in situ diffuse reflectance infrared Fourier transform (DRIFT) techniques. The characterization outcomes manifested that the CeVO4-CeO2 nanocomposite could inhibit its crystallinity and enhance the concentrations of chemisorbed oxygen species and Ce3+, which was advantageous to the SCR process. Moreover, the in situ DRIFT technique manifested that the NH3-SCR reaction over Ce0.75V0.25Oy was enhanced effectively through the mechanism of L-H. [ABSTRACT FROM AUTHOR]

CO pretreatment was found to effectively improve the SCR performance of CeO2, with over 90% at about 300 °C. The larger specific area and the decrease of CeO2 crystallization indicated the modification of the surface structure after CO pretreatment. Abundant Ce3+ species and active oxygen, better reducibility, and the higher surface adsorption capacity were mainly responsible for its enhanced SCR performance. DRIFT analysis revealed the presumed coexistence of two reaction routes that the L-H mechanism was related to the reaction temperature, while the reaction rate of E-R route was almost directly proportional to the NO concentration at a certain temperature, based on the kinetic calculation. In addition, the CO-pretreated CeO2 also exhibited a better poisoning tolerance for SO2 and H2O and excellent thermal stability and circularity. [ABSTRACT FROM AUTHOR]

Some fly ash components such as K could seriously weaken the catalytic performance of SCR catalyst. In this study, the core-shell-structured MnFeOx@TiO 2 catalyst is synthesized by dipping deposition method and used for the NH 3 -SCR reaction. The results show that MnFeOx@TiO 2 catalyst exhibits higher K resistance than MnFeOx/TiO 2 catalyst prepared by impregnation method. And the correlativity between the core-shell morphology and K resistance of MnFeOx@TiO 2 catalyst is studied by TEM, N 2 adsorption, XRD, XPS, TPR, TPD and in situ DRIFT. It can be found that the shell of TiO 2 has a protective effect on the active species in MnFeOx@TiO 2 catalyst. And the core-shell structure of MnFeOx@TiO 2 catalyst can produce more Mn4+ and chemisorbed oxygen species on its surface, improving reducibility and surface acidity. Moreover, the core-shell structure of MnFeOx@TiO 2 catalyst is beneficial to the adsorption of NH 3 and the formation of NO 2 , resulting in the favored SCR reaction via the Eley−Rideal and the Langmuir−Hinshelwood routes. Therefore, MnFeOx@TiO 2 catalyst shows excellent K tolerance. Image 1 • The core-shell structure of MnFeOx@TiO 2 catalyst could protect the active species from the contact with K species. • The morphology of MnFeOx@TiO 2 catalyst is propitious to the conversion from to NO 2. • The SCR process over MnFeOx@TiO 2 catalyst was advanced via both E-R and L-H modes. [ABSTRACT FROM AUTHOR]

TiO 2 supported Ce Mo catalyst (Ce Mo/TiO 2) were employed for the first time to simultaneously oxidize elemental mercury (Hg0) and reduce nitrogen monoxide (NO) under simulated SCR atmosphere. The combination of molybdenum oxides and cerium oxides exhibits obvious synergy for Hg0 oxidation and NO reduction. Ce Mo/TiO 2 -0.3 catalyst exhibited an excellent Hg0 oxidation and NO reduction efficiencies of over 90% at above 250 °C corresponding to gas hourly space velocity (GHSV) of 119,000 h−1 (NO reduction) and 1,190,000 h−1 (Hg0 oxidation). Brunauer-Emmett-Teller (BET) surface area was not the dominating factor affecting the Ce Mo/TiO 2 performance. Well-dispersion of active species, abundant chemisorbed oxygen and large surface oxygen capacity were responsible for its high catalytic activity. The presence of Hg0 exhibited a negligible effect on NO reduction. Low-concentration of NO inhibited the Hg0 oxidation while a relatively high concentration had a promotional effect inversely due to abundant NO 2. NH 3 consumed surface oxygen and competed to adsorb with Hg0 resulting in the deactivation of Hg0 oxidation while an excellent recovery was observed after simultaneous cutting off NH 3 and introduction of O 2. In addition, Ce Mo/TiO 2 -0.3 catalyst also presented an excellent resistance to SO 2 and H 2 O poisoning and a good stability and recyclability. The possible mechanism for simultaneous NO reduction and Hg0 oxidation was proposed for Ce Mo/TiO 2 catalysts. The process of NO reduction and Hg0 oxidation over Ce-Mo/TiO2 catalyst. Image 1 • It is the first time that Ce Mo/TiO 2 catalyst was employed for the research of simultaneous Hg0 oxidation and NO reduction. • Low-concentration of NO inhibited the Hg0 oxidation while a relatively high concentration had a promotional effect. • The presence of Hg0 exhibited a negligible effect on NO reduction. • Ce Mo/TiO 2 -0.3 catalyst had an excellent recovery for NH 3 inhibition and resistance to SO 2 poisoning. [ABSTRACT FROM AUTHOR]

In present study, the poisoning mechanism of Cl on V/TiO 2 catalyst for SCR removal of NOx using NH 3 as the reductant was explored by in situ DRIFT technique. The experimental results revealed that the existence of Cl did not change the SCR reaction mechanism over V/TiO 2 catalyst, which was mainly under the control of both E-R and L-H mechanisms. The deactivation of V/TiO 2 catalyst by Cl was mainly resulted from the inhibited adsorption of NH 3 and NOx species, accompanied by the decrease of the reactivity of adsorbed NH 3 species. Image 1 • The addition of Cl on V/TiO 2 catalyst has an inhibition effect on the adsorption of NH 3 and NOx species. • The reactivity of adsorbed NH 3 species over V/TiO 2 catalyst would decrease after the loading of Cl. • The addition of Cl on V/TiO 2 catalyst does not change the mechanism of NH 3 -SCR reaction over it. [ABSTRACT FROM AUTHOR]

Z-Scheme MoS2/g-C3N4 heterojunction photocatalysts were fabricated using a hydrothermal deposition procedure together with a calcination route, and then applied for CO2 photoreduction. Experimental results indicated that the 10% MoS2/g-C3N4 heterojunction displayed the best photocatalytic performance. Furthermore, the maximum CO yields of 58.59 μmol (g-cat)−1 under 7 h-visible light irradiation was up to 2.94 times that of the unadulterated g-C3N4. The enhanced photocatalytic performance of 10% MoS2/g-C3N4 catalyst was due to the favored visible light response, the efficient separation of photogenerated electron–hole pairs as well as its larger specific surface area. [ABSTRACT FROM AUTHOR]

Mn-TiO2 catalysts were utilized as an ozonation catalyst for the first time to study the simultaneous catalytic ozonation of Hg0 and NO at low flue gas temperatures. BET, SEM-EDS, XRD, XPS, H2-TPR, NOx-TPD and Hg0-TPD were used to characterize the catalysts. The Mn-TiO2 catalyst, in which the molar content of metal Mn was 60%, exhibited the best catalytic activities of Hg0 and NO oxidation, compared with other Mn-TiO2 catalysts. It was found that within the range of experiment, the catalytic ozonation efficiency of Hg0 and NO was higher than that of ozonation or catalytic oxidation. The results also showed that the presence of NO gas inhibited the catalytic ozonation of elemental mercury, and the inhibition was enhanced with the NO inlet concentration, while few elemental mercury molecules did promote the catalytic ozonation of NO. The addition of H2O vapor promoted the catalytic ozonation of Hg0 and NO. In addition, 0.6Mn-TiO2 catalyst demonstrated a good TOS and cyclic stability. The catalytic ozonation of NO and Hg0 on Mn-TiO2 catalyst likely followed the Langmuir-Hinshelwood mechanism, where the hydroxyl radicals reacted with adjacently adsorbed NO molecules and elemental mercury on catalyst surface. [ABSTRACT FROM AUTHOR]

Fe was used as the modifier to improve the performance of CeZr2Ox catalyst for the selective catalytic reduction (SCR) reaction with ammonia. Experimental results revealed that proper Fe species (Fe/Ce molar ratio = 2) could effectively improve the SCR activity of CeZr2Ox, along with the elevated resistance to SO2 and H2O. The characterization results including BET, XRD, H2-TPR and NH3-TPD confirmed that Fe species in Fe2CeZr2Ox catalyst could inhibit the formation of ZrO2 crystals and lead to higher reducibility and surface acidity. In addition, more Ce3+ and surface active oxygen species could be detected on Fe2CeZr2Ox compared with CeZr2Ox. By means of in situ DRIFT technique, it could be deduced that the SCR reaction process over Fe2CeZr2Ox was accelerated mainly through theL-H pathway due to the advanced adsorption of NH3 and NOx species, along with the promoted NO conversion to NO2. Therefore, the modification of CeZrOx catalyst by Fe had a significant stimulation effect on its low-temperature SCR performance. [ABSTRACT FROM AUTHOR]

Potassium has a serious deactivation effect on V/TiO catalyst for selective catalytic reduction of NO with NH. It was found that the doping of Cu can not only enhance the K resistance of V/TiO catalyst, but also enhance the low-temperature SCR activity. Based on the characterization results, it can be concluded that the good redox ability and NH adsorption capacity, and the increase of reduced vanadium species and active oxygen species are the main factors for the good performance of V-Cu/TiO catalyst. [ABSTRACT FROM AUTHOR]

It was well recognized that Pb had a poisoning effect on a SCR catalyst. In this study, the deactivation mechanism of Pb on the Ce/TiO2 catalyst was investigated based on the characterization results of TPD and in situ DRIFT studies. It was found that the addition of Pb on the Ce/TiO2 catalyst not only inhibited the adsorption and activation of NH3 species, but also led to the decrease of the activity of adsorbed NH3 species in the SCR reaction. The adsorption of NOx species and the oxidation of NO by O2 over the Ce/TiO2 catalyst were also suppressed by the addition of Pb, while the reactivity of adsorbed NO2 species did not decrease. Moreover, the results revealed that the NH3-SCR reaction over the Ce/TiO2 catalyst followed both the E–R and L–H mechanisms, while the NH3-SCR reaction over Ce/TiO2-Pb was mainly controlled by the L–H mechanism. The contributions of the L–H mechanism to the SCR reactions over Ce/TiO2 and Ce/TiO2-Pb decreased with increasing reaction temperature. The deactivation of Ce/TiO2-Pb was mainly attributed to the suppressed NH3 adsorption and activation, accompanied by the inhibited NO oxidation and the decrease of Brønsted acid sites. [ABSTRACT FROM AUTHOR]

NO (nitric oxide) is one of the main air pollutants emitted from coal-fired power plants. During the past several decades, capture of NO by liquid phase oxidation and the absorption process has drawn much attention for its advantages of low cost and co-capture of other pollutants. This paper provides a comprehensive review of recent development of liquid phase oxidation and the absorption process for NO capture. The process chemistry, effect of reaction parameters on absorption efficiency, and simultaneous capture with other pollutants in flue gas are critically summarized and reviewed. And the future development of this process is also referred to and discussed in brief. [ABSTRACT FROM AUTHOR]

The absorption of NO in aqueous solutions of KMnO4and H2SO4was carried out in a stirred tank reactor under atmosphere pressure. The results indicated that the absorption process was under a fast pseudo-mth reaction regime. The reaction between NO and aqueous solutions of KMnO4/H2SO4was found to be first-order with respect both to NO and to KMnO4. The addition of H2SO4to KMnO4solutions increased the absorption rate of NO and increasing reaction temperature was also favorable to the absorption of NO. [ABSTRACT FROM AUTHOR]

CeO2–CuO/Al2O3catalysts were prepared by three different methods and their activities for selective catalytic reduction (SCR) of NO with NH3were investigated. As can be seen from the experimental results, the catalyst prepared by the single-step sol–gel (SG) method showed the best SCR activity and resistance to SO2and H2O. In order to investigate the relationship between the preparation method and the performance of SCR catalysts, the catalysts were characterized by using Brunauer–Emmett–Teller, X-ray diffraction, temperature programmed reduction with hydrogen, temperature programmed desorption with ammonia, X-ray photoelectron spectroscopy, Fourier transform infrared and thermo-gravimetric analysis techniques. It was found that the excellent performance of CeO2–CuO/Al2O3catalyst prepared by the single-step SG method should be resulted from its large surface area, low crystallinity, high oxygen storage capacity, high NH3adsorption capacity, high concentration of surface chemisorbed oxygen, weak sulphation process and weak water absorption. [ABSTRACT FROM PUBLISHER]

CeO-CuO catalysts were prepared by citric acid method at different calcination temperatures. The purpose of this study is to investigate the influence of calcination temperature on the catalytic activity of CeO2-CuO catalyst for the selective catalytic reduction of NO with NH3. As can be seen from the results, Ce-Cu(450) is of the best low temperature selective catalytic reduction (SCR) activity among the three catalysts, which may be resulted from its large surface area, good redox ability, strong NH3 adsorption capacity, and high concentration of Cu2+ and active oxygen species on the surface. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 385-389, 2014 [ABSTRACT FROM AUTHOR]