Reduction of NO by CO using Pd-CeTb and Pd-CeZr catalysts supported on SiO2 and La2O3-Al2O3

The catalytic activity of Pd catalysts supported on Ce_0.73Tb_0.27O_x/SiO₂, Ce_0.6Zr_0.4O_x/SiO₂, Ce_0.73Tb_0.27O_x/La₂O₃-Al₂O₃ and Ce_0.6Zr_0.4O_x/La₂O₃-Al₂O₃ was studied using the reduction of NO by CO. The catalysts were characterized by X-ray fluorescence, surface area, X-ray diffraction, temperature-programmed reduction, CO chemisorption and oxygen storage capacity. Temperature-programmed reduction results indicated that Tb or Zr incorporation improves the reducibility and oxygen storage capacity. CO chemisorption data suggested the presence of large PdO particles due to the low CO/Pd ratio. No significant differences were obtained in light off temperatures (T_{Light off}) for all Pd catalysts and the most active was 1.5%Pd/Ce_0.6Zr_0.4O_x/SiO₂.     

Promoting effect of vanadium on catalytic activity of Pt/Ce–Zr–O diesel oxidation catalysts

A series of Pt–V/Ce–Zr–O diesel oxidation catalysts was prepared using the impregnation method. The catalytic activity and sulfur resistance of Pt–V/Ce–Zr–O were investigated in the presence of simulated diesel exhaust. The effect of vanadium on the structure and redox properties of the catalysts was also investigated using the Brunauer–Emmett–Teller method,X-ray diffraction, H2temperature-programmed reduction, CO temperature-programmed desorption, X-ray photoelectron spectroscopy, and Energy Dispersive Spectroscopy. Results showed that the Pt particles were well dispersed on the Ce–Zr–O carrier through the vanadium isolation effect, which significantly improved the oxidation activity toward CO and hydrocarbons. An electron-withdrawing phenomenon occurred from V to Pt, resulting in an increase in the metallic nature of platinum, which was beneficial to hydrocarbon molecular activation.     

A comparative investigation of NdSrCu_(1-x) Co_x O_(4-δ) and Sm_(1.8) Ce_(0.2) Cu_(1-x) Co_x O_(4-δ) (x:0–0.4) for NO decomposition

A series of single-phase T-structured NdSrCu 1-x Co x O 4-δ with oxygen vacancies and T -structured Sm 1.8 Ce 0.2 Cu 1-x Co x O 4-δ (x: 0–0.4) with oxygen excess were prepared using ultrasound-assisted citric acid complexing method, and characterized by means of techniques such as thermogravimetric analysis and NO temperature-programmed desorption (NO-TPD). The catalytic activities of these materials were evaluated for the decomposition of NO. It was found that the NdSrCu 1-x Co x O 4-δ catalysts were of oxygen vacancies whereas the Sm 1.8 Ce 0.2 Cu 1-x Co x O 4-δ ones possessed excessive oxygen (i.e., over-stoichiometric oxygen); with a rise in Co doping level, the oxygen vacancy density of NdSrCu 1-x Co x O 4-δ decreased while the over-stoichiometric oxygen amount of Sm 1.8 Ce 0.2 Cu 1-x Co x O 4-δ increased. The NO-TPD results revealed that NO could be activated much easier over the oxygen-deficient perovskite-like oxides than over the oxygen-excessive perovskite-like oxides, with the NdSrCuO 3.702 catalyst showing the best efficiency in activating NO molecules. Under the conditions of 1.0% NO/helium, 2800 hr -1 , and 600–900°C, the catalytic activity of NO decomposition followed the order of NdSrCuO 3.702 NdSrCu 0.8 Co 0.2 O 3.736 NdSrCu 0.6 Co 0.4 O 3.789 Sm 1.8 Ce 0.2 Cu 0.6 Co 0.4 O 4.187 Sm 1.8 Ce 0.2 Cu 0.8 Co 0.2 O 4.104 Sm 1.8 Ce 0.2 CuO 4.045 , in concord with the sequence of decreasing oxygen vacancy or oxygen excess density. Based on the results, we concluded that the higher oxygen vacancy density and the stronger Cu 3+ /Cu 2+ redox ability of NdSrCu 1-x Co x O 4-δ account for the easier activation of NO and consequently improve the catalytic activity of NO decomposition over the catalysts.     

Effect of lanthanum loading on nanosized CeO2-ZnO solid catalysts supported on cordierite for diesel soot oxidation

We report the application of a solid lanthanum–ceria–zinc catalyst in the catalytic regeneration of diesel particulate filters(DPF) in diesel engines.We synthesized a CeO_2–ZnO–La_2O_3(Ce–Zn–La) mixed oxide by a lactic acid-mediated sol–gel method,which efficiently coated cordierite substrates for soot capture and combustion.We studied the effects of La loading on the physicochemical and catalytic properties of Ce–Zn mixed oxide during lowtemperature soot combustion processes.We characterized the synthesized catalysts by X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR),N2 adsorption,Raman spectroscopy,oxygen storage capacity(OSC),and scanning and transmission electron microscopy(SEM and TEM).Thermogravimetric and differential thermal analysis(TGA/DTA)confirmed that the catalysts effectively reduced the soot oxidation temperature.The ternary Ce–Zn–La mixed oxide catalyst with Ce/Zn/La atomic ratio of 2:1:0.5 had the highest catalytic activity and promoted soot oxidation at temperatures below 390°C.This indicated that the large number of oxygen vacancies in the catalyst structure generated oxygen species at low temperatures.Raman spectroscopy measurements revealed the presence of oxygen vacancies and lattice defects in Ce–Zn–La samples,which were key parameters concerning the stability and redox properties of the prepared catalysts.     

Mo-modified Pd/Al2O3 catalysts for benzene catalytic combustion

Mo-modified Pd/Al2O3catalysts were prepared by an impregnation method and tested for the catalytic combustion of benzene. The catalysts were characterized by N2 isothermal adsorption, X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, temperatureprogrammed desorption of NH3（NH3-TPD）, H2temperature-programmed reduction（H2-TPR）, and high-angle annular dark-field scanning transmission electron microscopy（HAADF-STEM）. The results showed that the addition of Mo effectively improved the activity and stability of the Pd/Al2O3catalyst by increasing the dispersion of Pd active components, changing the partial oxidation state of palladium and increasing the oxygen species concentration on the surface of catalyst. In the case of the Pd-Mo/Al2O3catalyst,benzene conversion of 90% was obtained at temperatures as low as 190°C, which was 45°C lower than that for similar performance with the Pd/Al2O3catalyst. Moreover, the 1.0% Pd-5% Mo/Al2O3catalyst was more active than the 2.0% Pd/Al2O3catalyst. It was concluded that Pd and Mo have a synergistic effect in benzene catalytic combustion.     

Effects of synthesis methods on the performance of Pt + Rh/Ce0.6Zr0.4O2 three-way catalysts

The 0.7 wt% Pt + 0.3 wt% Rh/Ce0.6Zr0.4O2 catalysts were fabricated via different methods, including ultrasonic-assisted membrane reduction(UAMR) co-precipitation, UAMR separation precipitation, co-impregnation, and sequential impregnation. The catalysts were physico-chemically characterized by N2 adsorption, XRD, TEM, and H2-TPR techniques, and evaluated for three-way catalytic activities with simulated automobile exhaust. UAMR co-precipitation- and UAMR separation precipitationprepared catalysts exhibited a high surface area and metal dispersion, wide λ window and excellent conversion for NOx reduction under lean conditions. Both fresh and aged catalysts from UAMRprecipitation showed the high surface areas of ca. 60–67 m2/g and 18–22 m2/g, respectively, high metal dispersion of 41%–55%, and small active particle diameters of 2.1–2.7 nm. When these catalysts were aged, the catalysts prepared by the UAMR method exhibited a wider working window(Δλ = 0.284–0.287) than impregnated ones(Δλ = 0.065–0.115) as well as excellent three-way catalytic performance, and showed lower T50(169.C) and T90(195.C) for NO reduction than the aged catalysts from impregnation processes, which were at 265 and 309.C, respectively. This implied that the UAMR-separation precipitation has important potential for industrial applications to improve catalytic performance and thermal stability. The fresh and aged 0.7 wt% Pt + 0.3 wt% Rh/Ce0:6Zr0:4O2 catalysts prepared by the UAMR-separation precipitation method exhibited better catalytic performance than the corresponding catalysts prepared by conventional impregnation routes.     

Effect of Ce doping of TiO2 support on NH3-SCR activity over V2O5-WO3/CeO2-TiO2 catalyst

CeO2–TiO2composite supports with different Ce/Ti molar ratios were prepared by a homogeneous precipitation method, and V2O5–WO3/CeO2–TiO2catalysts for the selective catalytic reduction（SCR） of NOx with NH3 were prepared by an incipient-wetness impregnation method. These catalysts were characterized by means of BET, XRD, UV–Vis,Raman and XPS techniques. The results showed that the catalytic activity of V2O5–WO3/TiO2 was greatly enhanced by Ce doping（molar ratio of Ce/Ti = 1/10） in the TiO2 support.The catalysts that were predominantly anatase TiO2 showed better catalytic performance than the catalysts that were predominantly fluorite CeO2. The Ce additive could enhance the surface adsorbed oxygen and accelerate the SCR reaction. The effects of O2 concentration, ratio of NH3/NO, space velocity and SO2 on the catalytic activity were also investigated. The presence of oxygen played an important role in NO reduction. The optimal ratio of NH3/NO was 1/1 and the catalyst had good resistance to SO2 poisoning.     

Effect of different reduction methods on Pd/Al2O3 for o-xylene oxidation at low temperature

Pd/Al₂O₃ was pretreated by CO, H₂ and NaBH₄ reduction, respectively. The reduced catalysts were tested for o-xylene oxidation and characterized by power X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and temperature-programmed decomposition of palladium hydride (TPDH). The characterizations indicate the pretreatments lead to distinct Pd particle sizes and amount of surface activated oxygen species, which are responsible for the catalytic performance. Compared with H₂ and NaBH₄ reduction methods, CO reduction shows a strong interaction between Pd and Al₂O₃ with smaller Pd particle size and more surface activated oxygen. It exhibited excellent catalytic performance, complete oxidation of 50 ppmV o-xylene at 85°C with a WHSV of 60,000 mL/(g∙hr).     

Iron-doped Mn-Ce/TiO2 catalyst for low temperature selective catalytic reduction of NO with NH3

The catalysts of iron-doped Mn-Ce/TiO 2(Fe-Mn-Ce/TiO 2) prepared by sol-gel method were investigated for low temperature selective catalytic reduction(SCR) of NO with NH 3.It was found that the NO conversion over Fe-Mn-Ce/TiO 2 was obviously improved after iron doping compared with that over Mn-Ce/TiO 2.Fe-Mn-Ce/TiO 2 with the molar ratio of Fe/Ti = 0.1 exhibited the highest activity.The results showed that 96.8% NO conversion was obtained over Fe(0.1)-Mn-Ce/TiO 2 at 180°C at a space velocity of 50,000 hr 1.Fe-Mn-Ce/TiO 2 exhibited much higher resistance to H 2 O and SO 2 than that of Mn-Ce/TiO 2.The properties of the catalysts were characterized using X-ray diffraction(XRD),N 2 adsorption,temperature programmed desorption(NH 3-TPD and NOx-TPD),and Xray photoelectron spectroscopy(XPS) techniques.BET,NH3-TPD and NOx-TPD results showed that the specific surface area and NH3 and NOx adsorption capacity of the catalysts increased with iron doping.It was known from XPS analysis that iron valence state on the surface of the catalysts were in Fe3+ state.The doping of iron enhanced the dispersion and oxidation state of Mn and Ce on the surface of the catalysts.The oxygen concentrations on the surface of the catalysts were found to increase after iron doping.Fe-Mn-Ce/TiO2 represented a promising catalyst for low temperature SCR of NO with NH3 in the presence of H2 O and SO2.     

A comparative investigation of NdSrCu1-xCoxO4-σ and Sm1:8Ce0:2Cu1-xCoxO4-σ(x: 0-0.4) for NO decomposition

A series of single-phase T-structured NdSrCu1??xCoxO4?? with oxygen vacancies and T0-structured Sm1:8Ce0:2Cu1??xCoxO4?? (x: 0–0.4) with oxygen excess were prepared using ultrasound-assisted citric acid complexing method, and characterized by means of techniques such as thermogravimetric analysis and NO temperature-programmed desorption (NO-TPD). The catalytic activities of these materials were evaluated for the decomposition of NO. It was found that the NdSrCu1??xCoxO4?? catalysts were of oxygen vacancies whereas the Sm1:8Ce0:2Cu1??xCoxO4?? ones possessed excessive oxygen (i.e., over-stoichiometric oxygen); with a rise in Co doping level, the oxygen vacancy density of NdSrCu1??xCoxO4?? decreased while the over-stoichiometric oxygen amount of Sm1:8Ce0:2Cu1??xCoxO4?? increased. The NO-TPD results revealed that NO could be activated much easier over the oxygen-deficient perovskite-like oxides than over the oxygen-excessive perovskite-like oxides, with the NdSrCuO3:702 catalyst showing the best e ciency in activating NO molecules. Under the conditions of 1.0% NO/helium, 2800 hr??1, and 600–900°C, the catalytic activity of NO decomposition followed the order of NdSrCuO3:702 > NdSrCu0:8Co0:2O3:736 > NdSrCu0:6Co0:4O3:789 > Sm1:8Ce0:2Cu0:6Co0:4O4:187 > Sm1:8Ce0:2Cu0:8Co0:2O4:104 > Sm1:8Ce0:2CuO4:045, in concord with the sequence of decreasing oxygen vacancy or oxygen excess density. Based on the results, we concluded that the higher oxygen vacancy density and the stronger Cu3+/Cu2+ redox ability of NdSrCu1??xCoxO4?? account for the easier activation of NO and consequently improve the catalytic activity of NO decomposition over the catalysts.     

Synergistic effect of palladium and oxygen vacancies in the Pd/perovskite catalysts synthesized by the spc method

A series of oxygen-deficient perovskite-supported palladium catalysts were prepared by the “solid phase crystallization“(spc) ethod and investigated with XRD, TPR, TPD, TEM, XPS, BET analysis and CO oxidation. It was found that Pd/perovskite catalysts ynthesized by the spc method were more active for CO oxidation than the calcined LaCoo.95 Pdo.05 03, where Pd dispersed in the solid olution. H2-reducing treatment in the spc method could yield not only high-dispersed fine Pd particles on the perovskite surface but also xygen-deficient structure. In these perovskite-supported Pd catalysts, oxygen vacancies adsorbed, activated and supplied oxygen to the ctive Pd sites, where the oxidation occurred with adsorbed CO. The high activities were due to the cooperative action of Pd and oxygen acancies.     

Highly selective catalytic reduction of NOxby MnOx–CeO2–Al2O3 catalysts prepared by self-propagating high-temperature synthesis

We first present preparation of MnOx–CeO_2–Al_2O_3 catalysts with varying Mn contents through a self-propagating high-temperature synthesis(SHS) method, and studied the application of these catalysts to the selective catalytic reduction of NOxwith NH3(NH_3-SCR).Using the catalyst with 18 wt.% Mn(18 MnCe1Al2), 100% NO conversion was achieved at 200°C and a gas hourly space velocity of 15384 hr-1, and the high-efficiency SCR temperature window, where NO conversion is greater than 90%, was widened to a temperature range of 150–300°C. 18 MnCe1Al2 showed great resistance to SO_2(100 ppm)and H_2O(5%) at 200°C. The catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller(BET) analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and H_2 temperature programmed reduction. The characterization results showed that the surface atomic concentration of Mn increased with increasing Mn content, which led to synergism between Mn and Ce and improved the activity in the SCR reaction. 18 MnCe1Al2 has an extensive pore structure,with a BET surface area of approximately 135.4 m~2/g, a pore volume of approximately 0.16 cm~3/g, and an average pore diameter of approximately 4.6 nm. The SCR reaction on 18 MnCe1Al2 mainly followed the Eley-Rideal mechanism. The performances of the MnOx–CeO_2–Al_2O_3 catalysts were good, and because of the simplicity of the preparation process,the SHS method is applicable to their industrial-scale manufacture.     

A novel four-way combining catalysts for simultaneous removal of exhaust pollutants from diesel engine

A novel four-way combining catalysts containing double layers was applied to simultaneously remove four kinds of exhaust pollutants(NOx,CO,HC and PM) emitted from diesel engine.The four-way catalysts were characterized using scanning electron microscope(SEM) and Ultraviolet visible diffuse reflectance spectroscopy(UV-Vis DRS).Their catalytic performances were evaluated by temperature-programmed reaction technology.The double layer catalysts could effectively remove the four main pollutants.The highest catalytic activity was given by the two-layered catalysts of La0.6K0.4CoO3/Al2O3 and W/HZSM-5.Under the simulated exhaust gases conditions,the peak temperature of the soot combustion was 421°C,the maximal conversion of NO to N2 was 74%,the temperature of the HC total conversion was 357°C,and the maximum conversion ratio of CO was 99%.     

VxMn(4 − x)Mo3Ce3/Ti catalysts for selective catalytic reduction of NO by NH3

A series of vanadium based catalysts(VxMn(4-x)Mo3Ce3/Ti) with different vanadium(x wt.%) and manganese((4-x) wt.%) contents have been prepared by the wet impregnation method and investigated for selective catalytic reduction(SCR) of NO_x by NH_3 in the presence of 8 vol.% H_2O and 500 ppm V SO_2.The physicochemical characteristics of the catalysts were thoroughly characterized.The SCR of NO_x by NH_3(NH_3-SCR) activity, especially the low-temperature activity, significantly increased with increasing V_2O_5 content in the catalyst until the V_2O_5 content reached 1.5 wt.%, which corresponds well with the redox properties of the catalyst.All of the metal oxides were well dispersed and strongly interacted with each other on the catalyst surface.V mainly exists in the V~(5+)state in the catalysts.The strong synergistic effect between the vanadium and cerium species led to formation of more Ce~(3+)species, and that between the vanadium and manganese species contributed to formation of more manganese species with low valences.All of the catalysts exhibited strong acidity, while the redox properties determined the NH_3-SCR activity, especially the low-temperature activity.H_2O and SO_2 had severe inhibiting effects on the activity of V1.5Mn2.5Mo3Ce3/Ti.However, good H_2O and SO_2 resistance and high NO_x conversion by V1.5Mn2.5Mo3Ce3/Ti could be achieved in the presence of SO_2 and almost no decline was observed in a long-term test at 275℃ for 168 hr in the presence of SO_2 and H_2O, which can be attributed to the sulfate species formed on the catalyst surface.     

Effect of CeO2 and Al2O3 on the activity of Pd/Co_3O_4/cordierite catalyst in the three-way catalysis reactions (CO/NO/CnHm)

The present article studies the effect of CeO₂ and Al₂O₃ on the activity of Pd/Co₃O₄/cordierite catalyst in conversion of NO, CO, C_nH_m. The catalysts were characterized by temperature programmed reduction with hydrogen, X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. It is shown that the effect of CeO₂ on the properties of Pd/Co₃O₄/cordierite catalyst depends on preparation method. The catalyst obtained by co-deposition of cerium and cobalt oxides has higher activity in CO oxidation (CO + O₂ and CO + NO) and total hexane oxidation (C₆H₁₄ + O₂). Such phenomenon is probably caused by more than stoichiometric amount of formed oxygen vacancies, an increase in both mobility of surface oxygen and dispersity of components in the catalytic composition. It is demonstrated that CeO₂ addition promotes the SO₂ resistance of Pd/Co₃O₄/cordierite. The second support decreases the activity of Pd/Co₃O₄/cordierite catalyst in the reactions of CO and C₆H₁₄ with oxygen because of CoAl₂O₄ formation.     

Effects of Ce on catalytic combustion of methane over Pd-Pt/Al2O3 catalyst

Activity and stability of 1%Pd-0.2%Pt/Al₂O₃ and 1%Pd-0.2%Pt/0.6%Ce/Al₂O₃ catalysts prepared by impregnation method for catalytic combustion of methane in air were investigated. The catalysts before and after reaction were characterized by BET, CO chemisorption, XRD and XPS techniques. Results showed that the presence of Ce significantly increased the activity and thermal stability of the Pd-Pt/Al₂O₃ catalyst towards methane combustion, which could be attributed to more highly-dispersed active PdO particles over the Pd-Pt/Ce/Al₂O₃ catalyst surface as well as the retarded sintering of PdO and the maintained oxidized state of surface Pd during the combustion process in the presence of Ce.     

Effects of metal and acidic sites on the reaction by-products of butyl acetate oxidation over palladium-based catalysts

Catalytic oxidation is widely used in pollution control technology to remove volatile organic compounds. In this study, Pd/ZSM-5 catalysts with different Pd contents and acidic sites were prepared via the impregnation method. All the catalysts were characterized by means of N2 adsorption- desorption, X-ray fluorescence （XRF）, HE temperature programmed reduction （H2-TPR）, and NH3 temperature programmed desorption （NH3-TPD）. Their catalytic performance was investigated in the oxidation of butyl acetate experiments. The by-products of the reaction were collected in thermal desorption tubes and identified by gas chromatography/mass spectrometry. It was found that the increase of Pd content slightly changed the catalytic activity of butyl acetate oxidation according to the yield of CO2 achieved at 90%, but decreased the cracking by-products, whereas the enhancement of strong acidity over Pd-based catalysts enriched the by-product species. The butyl acetate oxidation process involves a series of reaction steps including protolysis, dehydrogenation, dehydration, cracking, and isomerization. Generally, butyl acetate was cracked to acetic acid and 2- methylpropene and the latter was an intermediate of the other by-products, and the oxidation routes of typical by-products were proposed. Trace amounts of 3-methylpentane, hexane, 2-methylpentane, pentane, and 2-methylbutane originated from iso4merization and protolysis reactions.     

Au − Pd/mesoporous Fe2O3: Highly active photocatalysts for the visible-light-driven degradation of acetone

Three-dimensionally ordered mesoporous Fe_2O_3(meso-Fe_2O_3) and its supported Au, Pd,and Au-Pd alloy(xA uP dy/meso-Fe_2O_3; x = 0.08–0.72 wt.%; Pd/Au molar ratio(y) = 1.48–1.85)photocatalysts have been prepared via the KIT-6-templating and polyvinyl alcohol-protected reduction routes, respectively. Physical properties of the samples were characterized, and their photocatalytic activities were evaluated for the photocatalytic oxidation of acetone in the presence of a small amount of H_2O_2 under visible-light illumination. It was found that the meso-Fe_2O_3 was rhombohedral in crystal structure. The as-obtained samples displayed a high surface area of 111.0–140.8 m~2/g and a bandgap energy of 1.98–2.12 eV. The Au, Pd and/or Au–Pd alloy nanoparticles(NPs) with a size of 3–4 nm were uniformly dispersed on the surface of the meso-Fe_2O_3 support. The 0.72 wt.% AuP d1.48/meso-Fe_2O_3 sample performed the best in the presence of 0.06 mol/L H_2O_2 aqueous solution, showing a 100% acetone conversion within4 hr of visible-light illumination. It was concluded that the good performance of 0.72 wt.%AuPd_(1.48)/meso-Fe_2O_3 for photocatalytic acetone oxidation was associated with its ordered mesoporous structure, high adsorbed oxygen species concentration, plasmonic resonance effect between AuPd_(1.48) NPs and meso-Fe_2O_3, and effective separation of the photogenerated charge carriers. In addition, the introduction of H_2O_2 and the involvement of the photo-Fenton process also played important roles in enhancing the photocatalytic activity of 0.72 wt.%AuPd_(1.48)/meso-Fe_2O_3.     

NH3-SCR denitration catalyst performance over vanadium-titanium with the addition of Ce and Sb

Selective catalytic reduction technology using NH3 as a reducing agent(NH3-SCR) is an effective control method to remove nitrogen oxides. TiO2-supported vanadium oxide catalysts with different levels of Ce and Sb modification were prepared by an impregnation method and were characterized by X-ray diffractometer(XRD), Brunauer–Emmett–Teller(BET), Transmission electron microscopy(TEM), Fourier transform infrared spectroscopy(FT-IR), UV–Vis diffuse reflectance spectroscopy(UV–Vis DRS), Raman and Hydrogen temperature-programmed reduction(H2-TPR). The catalytic activities of V5 CexS by/TiO2 catalysts for denitration were investigated in a fixed bed flow microreactor. The results showed that cerium, vanadium and antimony oxide as the active components were well dispersed on TiO2, and the catalysts exhibited a large number of d–d electronic transitions, which were helpful to strengthen SCR reactivity. The V5 CexS by/TiO2 catalysts exhibited a good low temperature NH3-SCR catalytic activity. In the temperature range of 210 to 400℃, the V5 CexS by/TiO2 catalysts gave NO conversion rates above 90%. For the best V5Ce35Sb2/TiO2 catalyst, at a reaction temperature of 210℃, the NO conversion rate had already reached 90%. The catalysts had different catalytic activity with different Ce loadings. With the increase of Ce loading, the NO conversion rate also increased.     

Integrated CO2 capture and reduction catalysis:Role of γ-Al2O3 support,unique state of potassium and synergy with copper

Carbon dioxide capture and reduction (CCR) process emerges as an efficient catalytic strategy for CO₂ capture and conversion to valuable chemicals.K-promoted Cu/Al₂O₃ catalysts exhibited promising CO₂ capture efficiency and highly selective conversion to syngas(CO+H₂).The dynamic nature of the Cu-K system at reaction conditions complicates the identification of the catalytically active phase and surface sites.The present work aims at more pr...