High Gas Hourly Space Velocity Research Articles

Research on reaction conditions and mechanism for simultaneous removal of NO and Hg0 over Cu[sbnd]Fe modified activated carbon at low temperature

In this study, modified microwave coconut shell activated carbon (CuFe/MCSAC) was used to simultaneously remove NO and Hg0 in the industrial tail gas. The influences of reaction condition were investigated, such as NH3 concentration, O2 content, gas hourly space velocity (GHSV), resistance of SO2 and H2O. Under the optimal reaction conditions (600 ppm NH3, 3% O2 and 30000 h−1 GHSV), CuFe/MCSAC showed high NO conversion rate (86%), high Hg0 conversion rate (61%) and low N2O concentration (81 ppm) at 225 °C. NH3 was conducive to the removal of NO, but it had a competitive adsorption effect for Hg0. O2 promoted oxidation of NO and Hg0, and led to the formation of N2O. Low GHSV had the external diffusion effect, which affected the reaction rate. High GHSV could not provide enough reaction time. H2O and SO2 were not conducive to the selectivity of SCR reaction and oxidation of Hg0.

Thin-felt Al-fiber-structured Pd-Co-MnOx/Al2O3 catalyst with high moisture resistance for high-throughput O3 decomposition

Thin-felt microfibrous-structured Pd-Co-MnOx/Al2O3/Al-fiber catalysts (named Pd-Co-MnOx-Al) with low Pd-loading engineered from micro- to macro-scale are developed for the high-throughput catalytic decomposition of high level gaseous ozone (O3) under humid conditions. The catalysts are obtained by highly dispersing Pd-Co-Mn active components onto the γ-Al2O3 nanosheets endogenously grown on the thin-felt microfibrous structure consisting of 10 vol% 60 μm-Al-fiber and 90 vol% voidage, using impregnation method. This approach effectively and efficiently couples the unique form factor, thin-sheet feature, and high permeability with the high activity, markedly improved stability, and enhanced moisture resistance. The most promising 0.1Pd-Co-MnOx-Al (0.1 wt% Pd, 0.36 Co/Mn molar ratio, Co2O3 + MnO2 loading of 5 wt%) catalyst remains full O3 conversion for at least 4 h at 25 °C for a feed gas containing 1500 ± 45 ppm O3 even at a high relative humidity (RH) of 70%, using a high gas hourly space velocity of 48,000 mL gcat.–1 h–1; the full O3 conversion quickly slides to a flat of ~96% during 4 h testing at 90% RH whereas it is retrievable immediately after switching the feed gas to a dry one. The remarkable improvement of activity, stability and moisture resistance by Pd-doping of Co-MnOx-Al is, in nature, due to the highly improved and stabilized low-valent-Mn related oxygen vacancies (i.e., active sites) and markedly weakened H2O adsorption on the catalyst surface, which are verified by XRD, H2-TPR, O2-TPD, H2O-TPD and XPS measurements.

Cu-Promoted Cobalt Oxide Film Catalyst for Efficient Gas Emissions Abatement

Thin film catalysts have been recently reported as promising catalysts owing to their good catalytic activity and reduced material amount, leading to low-cost efficient catalysts for gaseous emissions control. Here, we report the slight loading of Cu in cobalt spinel using a one-step pulsed-spray evaporation chemical vapor deposition (PSE-CVD) synthesis technique for efficient short-chain volatile organic compounds (VOCs) emissions treatment. Crystalline structure and morphology analyses revealed nano-crystallite sizes and open-like morphology. The catalytic performance was evaluated through the complete oxidation of C3H6, as a short-chain representative model of VOCs, at a high gas hourly space velocity (GHSV). Very good activity was obtained towards the complete abatement of C3H6 at low temperature and no carbon monoxide (CO) was formed during the oxidation process. Slightly-promoted Co3O4 catalyst with Cu introduction resulted in high catalytic activity comparing to the performance of the catalysts in the literature, due to the high dispersion of Cu and high active surface oxygen amount. Moreover, to evaluate the capability of the used catalysts under near realistic reaction conditions, CO2 effect on the catalytic activity was performed and the catalyst exhibited very good results. Thus, the adopted slightly-doping strategy to tailor a high active catalyst at low temperature could establish a very promising route to strongly enhance the activity of such other catalysts towards gas emissions abatement at low temperature.

Effect of support materials and Ni loading on catalytic performance for carbon dioxide reforming of coke oven gas

To investigate the effect of support materials on catalytic performance in carbon dioxide reforming of coke oven gas, Ni-based catalysts supported on various metal oxides with various properties are prepared and evaluated. The support material affects the important properties related to the catalytic performance such as surface area, Ni dispersion, basicity, oxygen storage capacity, and interaction between Ni and support. Among the various catalysts on different metal oxides, Ni/MgOAl2O3 catalyst exhibits the highest CH4 conversion due to its high Ni dispersion, large surface area, and strong basicity. Hence, the Ni loading in the Ni/MgOAl2O3 catalyst is optimized. Ni loading performs the important roles to determine the Ni dispersion, the amount of Ni active sites, and basicity. 15 wt% Ni/MgOAl2O3 catalyst shows the highest catalytic activity even at a high gas hourly space velocity (GHSV) of 1,500,000 h−1, owing to the large amount of Ni active sites which related to Ni loading, Ni dispersion, and reduction degree. To confirm the stability of the 15 wt% Ni/MgOAl2O3 catalyst, catalytic reaction has been carried out for 50 h and noticeable catalytic deactivation is not observed for 50 h.

Effect of W on the acidity and redox performance of the Cu0.02Fe0.2WaTiOx (a = 0.01, 0.02, 0.03) catalysts for NH3-SCR of NO

A series of tungsten-modified Cu0.02Fe0.2TiOx catalysts (Cu0.02Fe0.2WaTiOx; a = 0.01, 0.02, and 0.03) was synthesized by sol-gel method. Their catalytic activities were investigated for the selective catalytic reduction (SCR) of NO with NH3, in the presence/absence of 5 vol.% H2O. The characterization techniques of XRD, BET, Raman, H2-TPR, NH3-TPD, XPS, in situ DRIFTS, and kinetic studies were used to reveal the effect of tungsten modification on the redox and acidity of the Cu0.02Fe0.2WaTiOx catalysts. The relationship among the species composition, acid property, and oxidation-reduction behavior of the Cu0.02Fe0.2WaTiOx catalysts was established. Results demonstrated that a moderate amount of tungsten doping can markedly enhance the specific surface area, improve the abundant Brönsted and Lewis acid sites, and tune the surface species composition, which all benefited high-performance catalysis. Water/sulfur resistance also improved because of the excellent acidity levels. Among the Cu0.02Fe0.2WaTiOx catalysts, Cu0.02Fe0.2W0.02TiOx showed the highest NO conversion, a wide reaction-temperature window (235–520 °C) with >90% NO conversion, high N2 selectivity, and high water/sulfur resistance even in the presence of 5 vol.% H2O. Moreover, Cu0.02Fe0.2W0.02TiOx retained its outstanding catalytic activity under a rather high gas hourly space velocity (GHSV) of 100,000 h−1. In conclusion, the combined effects of redox and sufficient acidities on catalytic activity played key roles in superior SCR performance and water/sulfur durability. Furthermore, the NH3-SCR reaction over Cu0.02Fe0.2W0.02TiOx may follow the Eley–Rideal reaction pathway according to the in situ DRIFTS and kinetic studies results.

Cooperative Catalysis of Nickel and Nickel Oxide for Efficient Reduction of CO2 to CH4

AbstractThe use of CO2 to produce value‐added energy chemicals is a promising means for renewable CO2 transformation in low‐carbon energy system, and CO2 methanation has attracted ever‐increasing interest. Herein, we report that the Ni/MCM‐41 catalyst with prominent cooperative effect of Ni and NiO is efficient for CH4 generation with CO2 conversion of 73.2 % and CH4 selectivity of 91.6 % at 400 °C and high gas hourly space velocity (GHSV) of 90000 mL gcat−1 h−1. Combined methodologies of in situ X‐ray diffraction, diffuse reflectance infrared Fourier transform spectroscopy, and ambient‐pressure X‐ray photoelectron spectroscopy reflect the structural evolvements of Ni/MCM‐41 catalyst, the presence of carbonyl intermediates, the co‐existence of metallic and oxidized Ni species with sufficient molar ratio of Ni0/Ni2+ under working conditions. H2 and CO2 molecules are preferentially adsorbed and chemically activated over Ni0 and Ni2+ species, respectively. The possible four‐step reaction mechanism involved carbonyl pathway and the cleavage of C=O bond from CO2 as the rate‐determining step over the engineered Ni/MCM‐41 catalyst was demonstrated.

High‐Performance Co‐MnOx Composite Oxide Catalyst Structured onto Al‐Fiber Felt for High‐Throughput O3 Decomposition

AbstractA highly active and efficient thin‐felt Al‐fiber‐structured Co‐MnOx composite oxide catalyst (named Co‐MnOx‐Al) with unique form factor and high permeability is developed for high‐throughput catalytic decomposition of gaseous ozone (O3). Thin‐sheet Al‐fiber felt (60 μm diameter; 90 vol % voidage) chips underwent a steam‐only oxidation and calcination for endogenously growing a 0.7‐μm‐thick mesoporous layer of γ‐Al2O3 nanosheets along with the Al‐fiber. Cobalt and manganese were placed onto the ns‐γ‐Al2O3/Al‐fiber chips by incipient wetness co‐impregnation method. The best catalyst is the one with a Co/Mn molar ratio of 0.36 and Co‐Mn loading of 5 wt % after calcining at 500 °C (named Co‐MnOx(0.36)‐Al), being able to achieve full O3 conversion at 25 °C for a feed gas containing 1000±30 ppm O3, using a high gas hourly space velocity of 48000 mL gcat.−1 h−1; full O3 conversion is retained in the absence of moisture till the testing end after 720 min; in case with a relative humidity of 50 %, O3 conversion slides from 88 % of the initial value to a flat of ∼66 % within 90 min. CoOx modification is paramount for improved formation of Mn2+ species while leading to the highest fraction of (Mn2++Mn3+) in total (Mn2++Mn3++Mn4+) and more oxygen vacancies on Co‐MnOx(0.36)‐Al catalyst surface.

Removal of Volatile Organic Compounds Driven by Platinum Supported on Amorphous Phosphated Titanium Oxide

Development of high efficiency catalyst is the key factor to catalytic combustion of volatile organic compounds (VOCs). Herein, amorphous mesoporous phosphated TiO 2 (ATO-P) with high specific surface area supported platinum catalyst was successfully fabricated. P-dopant can increase the surface area (up to 278.9 m2•g-1) of ATO-P, which is 21 times higher than that of pristine TiO 2 , and make the amorphous titanium oxide structure. The supported Pt catalyst with amorphous mesoporous feature shows impressive performance and excellent thermostability for VOCs oxidation. The Pt/ATO-P catalyst exhibits outstanding catalytic efficiency, the T 50 and T 90 (temperatures required for achieving conversions of 50% and 90%) are respectively 130℃ and 140℃, for toluene oxidation under high gas hourly space velocity (GHSV) of 36000 mL•h-1•g-1 and toluene concentration of 10000 mL•m-3. The performance is superior to the reference Pt/TiO 2 and comparable with the state-of-the-art catalysts. These findings can make a significant contribution on the new applications of amorphous mesoporous phosphated materials in VOCs removal. © 2020, Science Press. All right reserved.

Boron nitride wash-coated cordierite monolithic catalyst showing high selectivity and productivity for oxidative dehydrogenation of propane

Hexagonal boron nitride (h-BN) is a burgeoning catalyst for oxidative dehydrogenation of propane (ODHP) with impressive light olefins selectivity, which deserves further study to optimize the heat and mass transfer process with the aim of promoting the potential industrial application since ODHP is a highly exothermic process. Herein, h-BN wash-coated cordierite monolithic catalyst was designed through a chemical vapor deposition method using boron acid and urea as precursors, which was used for ODHP reaction and exhibited a ∼16.8% conversion of propane and 82.1% selectivity towards propylene, with only 3.7% selectivity of CO and no detected CO2, at temperature of 535 ℃ and a high gas hourly space velocity (GHSV) of 576,000 mL/gBNh. The typical structure of h-BN/Cordierite with well-developed straight-channel and short diffusive pathway of the thin wash-coated h-BN layer guarantee the mass transfer process at high GHSV, achieving a high propylene space time yield of 18.6 gC3H6 gBN−1 h−1 and improving the selectivity towards propylene and ethylene by suppressing secondary reactions of deep oxidation. Meanwhile, the high GHSV and excellent thermal conductivity of h-BN contribute to the heat transfer during reactions.

Effect of Cu doping on the SCR activity over the CumCe0.1-mTiOx (m = 0.01, 0.02 and 0.03) catalysts

A series of Ce0.1TiOx, Cu0.1Ox and CumCe0.1-mTiOx (m = 0.01, 0.02, 0.03) catalysts are prepared via a sol-gel method for the selective catalytic reduction (SCR) of NO with NH3. The samples are mainly characterized by X-ray diffraction (XRD), Raman, H2-TPR, NH3-TPD, separated NO/NH3 oxidation, X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to investigate the properties of the catalysts. Among the CumCe0.1-mTiOx (m = 0.01, 0.02, 0.03) catalysts, Cu0.01Ce0.09TiOx displays much better catalytic activity in the range of 170 °C–425 °C (> 90% NO conversion), N2 selectivity and resistance of SO2 and H2O even at high gas hourly space velocity. The XPS results verify that the introduction of Cu leads to a copper species enrichment environment and the formation of more surface Ce3+ and absorbed oxygen (Oα), which are in favor of the oxidation of NO to NO2, enhancing the activity at low temperature. Furthermore, in situ DRIFTS results confirm that the Langmuir-Hinshelwood (L-H) mechanism is predominant in the NH3-SCR process for the Cu0.01Ce0.09TiOx catalyst at 150 °C.

Fischer\u2013Tropsch synthesis: product distribution, operating conditions, iron catalyst deactivation and catalyst speciation

Laboratory experiments conducted for long time on stream (TOS: 14,350 h) provide information on Fischer–Tropsch synthesis (FTS) that is representative of time scales of industrial operations. Operation conditions that deliver desirable conversion and product distribution were investigated. Low gas hourly space velocity (GHSV) gave the highest conversion of 20.97% with the highest C5+ selectivity achieved was 59.77%, which was obtained at the highest GHSV level. A one-way ANOVA, followed by a post-hoc Bonferroni correction test, indicated a significant difference in response to GHSV with P(T <=t) two-tail values ranging from 1.5 × 10−4 to 2.7 × 10−35. The optimum condition for paraffin production is high pressure and low GHSV: in our experiments, this corresponded to 20.85 bar (abs): 648 h−1. Conversely, olefins production is favored low pressure and low GHSV [1.85 bar (abs): 648 h−1]. C5+ production was favored at high GHSV (2592 h−1) and was very sensitive to GHSV, as the sensitivity to C5+ products dropped sharply when the GHSV decreased to low values (from 1296 to 648 h−1); furthermore, the selectivity to C5+ was found to be independent of pressure. The pressure effect on selectivity is complex and selectivity toward overall gaseous (paraffin + olefin) hydrocarbons and C5+ does not seem to be significantly affected by variations in pressure. Long TOS FTS runs are possible ca. 14,500 h though product distribution trends tend to be changed. The catalyst survived long runs, though the selectivity to FTS became comparatively less favored than WGS with increasing TOS. Our findings may have useful implication for the design of a mobile small-scale biomass/waste to liquid process that would last for period similar to that of an industrial plant.

Performance analysis of a membrane‐based reformer‐combustor reactor for hydrogen generation

Hydrogen is mostly produced in conventional steam methane reforming plants. In this work, we proposed a membrane-based reformer-combustor reactor (MRCR) for hydrogen generation in order to improve heat recovery and overall thermal efficiency. The proposed configuration will also reduce the complexity in existing steam methane reforming (SMR) plants. The proposed MRCR comprises combustion zone, hydrogen permeate zone, and SMR zone. A computational fluid dynamics model was developed using ANSYS-Fluent software to simulate and analyze the performance of the proposed MRCR. Results show that high hydrogen yields were observed at high reformer pressures (RPs) and low gas hourly space velocities (GHSVs). Furthermore, by increasing the steam to methane ratio and addition of excess air in the combustion side, the hydrogen yield from the MRCR decreases. This is attributed to the reduction in the effective temperature of the hydrogen membrane. High RP, low GHSV, and low steam to methane ratio that increased the hydrogen yield also decreased carbon monoxide (CO) emissions. For an increased RP from 1 to 10 bar, the CO emission decreased by about 99%. The reduction in CO emission at high RP would be attributed to the effect of water gas shift reaction in the MRCR. Results of the extensive parametric study presented in this work can be used to determine the operating conditions based on tradeoffs between hydrogen yield (mole H2/mole CH4), hydrogen production rate (kg of H2/h), allowable CO emissions, and exhaust gas temperature for other applications such as gas turbine.

A New Insight into Active Cu2+ Species Properties in One‐Pot Synthesized Cu‐SSZ‐13 Catalysts for NOx Reduction by NH3

AbstractThe Cu‐SSZ‐13 catalysts with different copper content are prepared by one‐pot method and changing the mole ratio of Cu‐tetraethylenepentamine/Al2O3. Cu‐SSZ‐13 catalyst with 3.25 wt.% Cu exhibits excellent catalytic activity (operation temperature window of 145–490 °C), adaptability to high GHSV (gas hourly space velocity) and hydrothermal stability in NH3‐SCR reaction. The results of XRD Rietveld refinement coupled with H2‐TPR and EPR show that three active Cu2+ species (Cu1, Cu2 and Cu3) locate in various sites in the CHA (chabazite) structure and play different action in NH3‐SCR reaction. Cu1 species situated close to an eight‐membered‐ring play a crucial role in the low temperature activity for its optimum reduction ability. While Cu3 species located in the center of the hexagonal prism are the most stable and its content basically remains unchanged after SO2 pretreatment, which contributes to the excellent SO2 resistance.

Dual Roles of Nano-Sulfide in Efficient Removal of Elemental Mercury from Coal Combustion Flue Gas within a Wide Temperature Range.

Nanostructured zinc sulfide (Nano-ZnS) has been demonstrated to be an efficient adsorbent for removal of elemental mercury (Hg0). However, the Hg0 removal performance deteriorates once the flue gas temperature deviates from the optimal temperature of 180 °C. In this study, ultraviolet (UV) light, which is generally generated through corona discharge in electrostatic precipitators (ESPs), was adopted to enhance Hg0 removal by Nano-ZnS. With the UV irradiation, Nano-ZnS exhibited excellent performance in Hg0 removal within a much wide temperature range from room temperature to 240 °C. A Hg0 removal efficiency of 99% was achieved at 60 °C even under extremely adverse conditions, that is, gas flow with an extremely high gas hourly space velocity but without hydrogen chloride. At low temperatures, Hg0 was mainly oxidized by superoxide radicals (•O2-) and hydroxyl radicals (•OH) generated by UV photostimulation to form mercuric oxide (HgO). At high temperatures, most Hg0 was immobilized as mercuric sulfide (HgS), as both the enhanced chemisorption and the accelerated transformation of HgO to HgS facilitated the formation of HgS. Compared with commercial activated carbon, injection of Nano-ZnS can utilize the UV in ESPs to warrant a higher Hg0 removal efficiency within a much wider temperature range.

Hydrothermal Stability of CeO2-WO3-ZrO2 Mixed Oxides for Selective Catalytic Reduction of NOx by NH3.

CeO2-WO3-ZrO2 mixed oxides were prepared by the homogeneous precipitation method for the selective catalytic reduction of NOx with NH3 (NH3-SCR). The effects of hydrothermal aging on the catalytic performances of CeO2-WO3-ZrO2 were investigated. The results showed that CeO2-WO3-ZrO2 catalyst exhibited excellent NH3-SCR activity for removal of NOx and hydrothermal stability. After hydrothermal aging at 850 °C for 16 h, the optimum CeO2-WO3-ZrO2 catalyst could still realize 80% NOx conversion at 300-500 °C even under a high gas hourly space velocity of 250 000 h-1. The structural properties, redox ability, surface species, and acidity of fresh and hydrothermally aged CeO2-WO3-ZrO2 catalysts were characterized by N2-physisorption, XRD, Raman, H2-TPR, XPS, NH3-TPD, and in situ DRIFTS. The characterization results showed that decreases of 89% of the surface area and 71% of the NH3 storage capacity as well as new phase formation occurred for the CeO2-WO3-ZrO2 sample after hydrothermal aging at 850 °C for 16 h. The activity of hydrothermally aged CeO2-WO3-ZrO2 was mainly attributed to the retention of redox-acid sites and their interaction due to the formation of Ce-Zr solid solutions and Ce4W9O33.

Biogas dry reforming for syngas production on La promoted hydrotalcite-derived Ni catalysts

Biogas plays a key role in the emerging renewable energy market, and biogas utilization attracts increasing attention in the renewable energy industry. As biogas consists mainly of CH4 and CO2, one of the most suitable processes for its utilization is through dry reforming of methane (DRM) for synthesis gas (syngas) production. In this study, we demonstrate the feasibility of direct biogas reforming for syngas production over promoted hydrotalcite-derived (HT) Ni catalysts. A series of 20Ni-Mg-Al HT-like catalysts with different lanthanum (La) loadings were prepared to study the influence of La-promoter on the activity of the catalysts for biogas reforming through DRM. The catalysts were characterized by N2 physisorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), H2-chemisorption and scanning electron microscopy (SEM). DRM experiments were performed at 600 and 750 °C, at a very high gas hourly space velocity (GHSV) of 240,000 ml/(gcat·h). Furthermore, a comprehensive range of CO2/CH4 ratios was studied at 600 °C to assess the catalyst under different biogas compositions. Methane decomposition reactions together with post-mortem catalyst characterization were also carried out to study the influence of carbon deposition on the deactivation of the catalysts. The catalysts exhibited different behavior under different DRM reaction conditions. The 20Ni-4La catalyst showed the highest activity and stability with the highest one-pass CO2 conversion of 80.8% at 750 °C. The stability of the 20Ni-8La catalyst at different model biogas compositions and very high GHSV demonstrated the feasibility of our La-promoted HT-derived Ni catalysts in direct biogas reforming at a low temperature of 600 °C.

Excellent low temperature NH3-SCR activity over MnaCe0.3TiOx (a = 0.1–0.3) oxides: Influence of Mn addition

A convenient sol-gel method was used to prepare a series of MnaCe0.3TiOx (a = 0.1, 0.2, 0.3) catalysts and applied in selective catalytic reduction with NH3 (NH3-SCR) for NO removal. XRD, BET, Raman, H2-TPR, NH3-TPD, SO2-TPD, XPS and in situ DRIFTS were applied to analyze the texture structure, redox property, acidity and surface properties. The Mn0.1Ce0.3TiOx catalyst exhibited a dramatical performance that 100% NO conversion and above 90% N2 selectivity were obtained between 175 and 400 °C, even under high gas hourly space velocity of 80,000 h−1 and existence of SO2 and H2O. The results can be attributed to that Mn0.1Ce0.3TiOx catalyst possessed the most chemisorbed oxygen and suitable redox property derived from Ce3+ + Mn4+ ↔ Ce4+ + Mn3+ reaction. In situ DRIFTS revealed that the NH3-SCR reaction upon Mn0.1Ce0.3TiOx catalyst took place by L-H and E-R mechanisms below 175 °C while only E-R mechanism above 175 °C.

CVD synthesis of Cu-doped cobalt spinel thin film catalysts for kinetic study of propene oxidation

A series of Co-Cu binary oxides dispersed homogenously on an inert support were prepared by pulsed-spray evaporation chemical vapor deposition for kinetic study of catalytic combustion. The physicochemical properties of the as-prepared samples were comprehensively characterized in terms of structure, morphology and composition. The results disclosed the formation of cubic binary oxides with amorphous surface. With the progressive introduction of copper into the cobalt spinel, the crystallite size tended to increase due to the incorporation of large Cu2+ ionic radius. Co3+, Co2+, Cu2+, lattice and adsorbed oxygen species were confirmed to co-exist at the surfaces of the binary oxides. The obtained samples exhibited excellent performance for C3H6 oxidation with a high gas hourly space velocity of 150,000 mL·g−1·h−1. The light-off curves shifted towards lower temperature with more Cu incorporation, which was linked to the increase in Co3+/Co2+, and the rearrangement and synergetic effects of Co, Cu and lattice oxygen. The reaction rate increases linearly with the increase in C3H6 concentration by following r=1.12*[C3H6]0.27, without reaching kinetic limitation stage. Moreover, an attractive durability of the binary oxides was observed in the C3H6 oxidation during 50 h. This work provides an inspiration and attractive strategy to develop efficient Co-Cu binary oxides for catalytic applications.

Promoting effect of Au on Pd/TiO2 catalyst for the selective catalytic reduction of NOx by H2

Au promoted Pd/TiO2 catalysts with different Pd loading were investigated for the selective catalytic reduction of NOx by hydrogen (H2-SCR). The results showed that 1%Pd-0.5%Au/TiO2 catalyst exhibited the highest NOx conversion and N2 selectivity, as well as a wide activity temperature window. Moreover, the 1%Pd-0.5%Au/TiO2 catalyst offered remarkable resistance to high gas hourly space velocity (GHSV). XRD, XPS and TEM results illustrated that the excellent H2-SCR performance of 1%Pd-0.5%Au/TiO2 catalyst was closely related to the formed PdAu alloy and the higher dispersion of active sites compared with 1%Pd/TiO2. In-situ DRIFTS results revealed that more and new adsorbed nitrogen oxides species, as well as more adsorbed NH3 and NH4+ active species generated over 1%Pd-0.5%Au/TiO2 catalyst, thus accelerating the ability to active H2 atom and the subsequent reaction with adsorbed nitrogen oxides species.

Inductive Effect Boosting Catalytic Performance of Advanced Fe1–xVxOδ Catalysts in Low-Temperature NH3 Selective Catalytic Reduction: Insight into the Structure, Interaction, and Mechanisms

A series of vanadium doped Fe2O3 catalysts were synthesized using the homogeneous precipitation method and subjected to laboratory evaluation for selective catalytic reduction of NOx with NH3 (NH3-SCR). The best Fe0.75V0.25Oδ catalyst with a Fe/V mole ratio of 3/1 exhibited superior catalytic performance, achieving 100% NOx conversion at 200 °C over a wide temperature window from 175 to 400 °C, believed to be the best Fe-based low-temperature NH3-SCR catalyst identified to date. The Fe0.75V0.25Oδ catalyst also showed prominent resistance to high gas hourly space velocity (GHSV; 200 000 h–1) and strong durability to SO2 and H2O. Doping of V was shown to remarkably boost the catalytic activity, due to enhancement of the redox ability and surface acidity. XRD, Raman, and morphology results revealed that the incorporation of V had led to the formation of amorphous FeVO4 and Fe2O3. Coupling XPS and UV–vis diffuse reflectance spectra (DRS) results with DFT, it was discovered that the electron inductive effect b...