Ammonia Selective Catalytic Reduction Research Articles

Simple preparation of V2O5-WO3/TiO2/SiC catalytic membrane with highly efficient dust removal and NO reduction

Simplifing the preparation process is an efficient method to reduce process energy consumption and product costs. In this work, a one-step vacuum impregnation technology was developed for the preparation of V2O5-WO3/TiO2 catalyst modified SiC (VWTi/SiC) catalytic membranes. In comparison to VWTi/SiC (II) catalytic membrane prepared by the traditional two-step method, the VWTi/SiC (I-X) catalytic membrane prepared via one-step vacuum impregnation technology demonstrate significant advantages in terms of energy saving and consumption reduction. Owing to the strongest activation ability for O2 and NH3 induced by high V4+ species and strong V-W interaction, the optimal VWTi/SiC (I-500) can achieve 90 % ammonia selective catalytic reduction (NH3-SCR) denitrition efficiency at the temperature range from 200 °C to 350 °C, presenting a much higher NH3-SCR activity than VWTi/SiC (II-500). The evaluation of sulfur resistance, long-term stability and dust filtration performance proposed that VWTi/SiC (I-500) demonstrated excellent sulfur resistance and outstanding long-term stability and excellent dust filtration performance (particle interception rate exceeds 99.9 % for typical 2.5 μm silicon dioxide particles) at various condition. Therefore, the VWTi/SiC catalytic membrane prepared by one-step vacuum impregnation method holds great promise and development potential for high-temperature flue gas purification.

Hydrothermal Aging Enhances Nitrogen Oxide Reduction over Iron-Exchanged Zeolites at 150 °C.

Ammonia selective catalytic reduction (NH3-SCR) over copper- and iron-exchanged zeolites is a state-of-the-art technology for removal of nitrogen oxides (NOx, NO, and NO2) from exhaust emissions but suffers from poor low-temperature (i.e., 150 °C) activity. Here we show that hydrothermal aging of Fe-beta, Fe-ZSM-5, and Fe-ferrierite at 650 °C or higher leads to a remarkable increase in NOx conversion from ∼30 to ∼80% under fast NH3-SCR conditions at 150 °C. The practical relevance of this finding becomes more evident as an aged Fe-beta/fresh Cu-SSZ-13 composite catalyst exhibits ∼90% conversion. We propose that a neutral heteronuclear bis-μ-oxo ironaluminum dimer might be created within iron zeolites during hydrothermal aging and catalyze ammonium nitrate reduction by NO at 150 °C. Density functional theory calculations reveal that the activation free energy (125 versus 147 kJ mol-1) for the reaction of NO with adsorbed NO3- species, the rate-determining step of ammonium nitrate reduction, is considerably lower on the bis-μ-oxo ironaluminum site than on the well-known mononuclear iron-oxo cation site, thus greatly enhancing the overall SCR activity.

TEAOH-assisted cost-effective preparation of SSZ-13 using L zeolite as Al source

Developing an economical and high-efficiency synthesis pathway of SSZ-13 zeolite is of great significance for the ammonia selective catalytic reduction of nitrogen oxides (NH3-SCR of NOx) reactions. Herein, SSZ-13 zeolite were synthesized using L zeolite as the aluminum source in the presence of a mixed structure directing agent (SDA) composed of N,N,N, trimethtyl-1-adamantammonium hydroxide (TMAdaOH) and tetraethylammonium hydroxide (TEAOH). This synthesis strategy aims to accelerate the crystallization rate through interzeolite transformation, while less expensive TEAOH can play a cooperative structure-directing role, thus reducing the consumption of expensive TMAdaOH template. The results showed that pure SSZ-13 zeolites with high crystallinity can be obtained from L zeolite within 12 h at 160 ℃ under low TMAdaOH/SiO2 ratio of 0.05 (too low to carry out the synthesis on its own in the current synthesis system) in the presence of TEAOH. Moreover, the crystallization mechanism was also investigated by XRD, FT-IR, SEM and TG-DTG techniques. It was proposed that the crystallization of SSZ-13 occurs through the formation of SSZ-13 nuclei under the direction of TMAdaOH and promotion of TEAOH, subsequently TMAdaOH was incorporated in the framework to further induce the crystal growth of SSZ-13. Especially, the zeolite crystal size can be modulated by the amount of TEAOH added. In addition, After Cu2+ exchange, the obtained Cu-SSZ-13 sample exhibits superior catalysis performance in the NH3-SCR of NOx reaction, and the NOx conversion rate remained over 90 % across a broad range from 200 to 600 °C, demonstrating its significant application potentials in NOx removal from diesel vehicle exhausts.

Novel insights for simultaneous NOx and CO Removal: Cu+-Sm3+-Ov-Ti4+ asymmetric active site promoting NH3-SCR coupled with CO oxidation reaction

Ammonia selective catalytic reduction (NH3-SCR) coupled with CO oxidation is a promising approach for simultaneous removal of NOx and CO. However, finding a bifunctional catalyst that can effectively facilitate both reactions remains a significant challenge. This study investigates the enhancing effect of Cu+-Sm3+-Ov-Ti4+ asymmetric active sites on the oxidation reaction of NH3-SCR coupled with CO oxidation. The traditional Cu/TiO2 catalyst can achieve a maximum NOx conversion of 75 % at 225 °C, while the CuSmOTi catalyst can achieve 100 % NOx conversion at 200 °C. The successful construction of the asymmetric active site leads to an increase in Cu+ content, producing abundant oxygen vacancies, accelerating the redox cycle in the reaction process, and improving the adsorption capacity of CO. Additionally, compared with the 8.4 % Cu dispersion on the Cu/TiO2 catalyst, the Cu dispersion on the SmCuOTi catalyst is as high as 75.0 %, which improves the reduction performance of the catalyst. A large number of Lewis acid sites optimize the activation and adsorption of the catalyst to the reactants. In-situ DRIFTS analysis indicates that the NH3-SCR reaction on the CuSmOTi catalyst primarily follows the (E-R) mechanism, while CO oxidation follows the (MvK) mechanism. Moreover, the formation of a significant number of amide intermediates during the reaction process enhances the N2 selectivity. These findings present a novel concept of utilizing asymmetric active sites in NH3-SCR coupled with CO oxidation reactions, provides valuable insights for achieving the complete removal of nitrogen oxides and carbon monoxide in the case of “0″ by-products.

The discrepancy of NH3 oxidation mechanism between SAPO-34 and Cu/SAPO-34.

The difference of NH3 oxidation mechanism over SAPO-34 and Cu-SAPO-34 was studied. XRD (X-ray diffraction), SEM (scanning electron microscopy) and H2-TPR (H2-temperature programmed desorption) were conducted to estimate the Cu species distribution. The quantity of individual Cu2+ ions escalated with the elevation of silicon content in the Cu/SAPO-34 catalysts, leading to an enhancement in the activity of the NH3-SCR (ammonia-selective catalytic reduction) process. This augmentation in activity can be attributed to the increased presence of isolated Cu2+ species, which are pivotal in facilitating the catalytic reaction. In addition, the kinetic test of NH3 oxidation indicated that the CuO species were the active sites for NH3 oxidation. Specifically, the strong structural Brønsted acid sites were the NH3 oxidation active sites over the SAPO-34 support, and the NH3 reacted with the O2 on the Brønsted acid sites to produce the NO mainly. While the NH3 oxidation mechanism over Cu/SAPO-34 consisted of two steps: firstly, NH3 reacted with O2 on CuO sites or residual Brønsted acid sites to form NO as the product; subsequently, the generated NO was reduced by NH3 into N2 on isolated Cu2+ sites. Simultaneously, the isolated Cu2+ sites might demonstrate a significant function in the NH3 oxidation process to form N2. The identification of active sites and corresponding mechanism could deepen the understanding of excellent performance of NH3-SCR over the Cu/SAPO-34 catalyst at high temperature.

Oxalic acid-mediated regeneration strategy and mechanism of phosphorus poisoned CeO2/TiO2 catalysts for selective catalytic reduction of NOx with NH3

The development of the regeneration strategies can extend the service life of deactivated catalysts and improve resource efficiency. In this work, an acid treatment method was proposed to regenerate the P-poisoned CeO2/TiO2 (PCeTi) catalyst for ammonia selective catalytic reduction (NH3-SCR) of NOx. Catalytic activity test results showed that acid treatment could achieve the efficient regeneration of PCeTi catalyst, the regenerated PCeTi mediated with oxalic acid (PCeTi-OA) catalyst showed a 90% mineralization temperature (T90) of 236 °C (T90 for fresh CeTi was 232 °C) and retained the promotional effect of P species at the high temperature (>350 °C). The characterization results showed that most of the P species on the PCeTi catalyst were removed after regeneration, which restored the majority of the original Ce-O active structure, thereby promoting the Ce4+/Ce3+ redox cycling and inducing the formation of new oxygen vacancies. At the same time, the residual P-O structures and new oxygen vacancies could provide a large amount of acid sites, which was favorable for the adsorption and activation of NH3. The recovered redox properties and the increased surface acidity of the PCeTi-OA catalyst were responsible for its recovered low temperature activity and superior high temperature activity, respectively.

Synthesis of MnO(OH) nanorods via hydrothermal method as efficient low-temperature SCR catalysts

We conducted a hydrothermal reaction using lactic acid as a reducing agent and potassium permanganate. This reaction successfully produced MnO(OH) with a one-dimensional nanorod structure, and its XRD spectrum perfectly matched the standard reference. Despite the excellent low-temperature ammonia selective catalytic reduction (NH3-SCR) performance observed in manganese-based catalysts, there was no reported performance data for any type of MnOOH in NH3-SCR prior to our research. Our test results now reveal that MnO(OH) nanorods, synthesized using this method, consistently maintain an impressive 98.8 % NO conversion rate even at the low temperature of 80 °C. This finding is of significant importance for the advancement of low-temperature NH3-SCR catalysts.

Catalytic properties of CeO2/TiO2 synthesized by different methods towards the organic dye photodegradation and NH3 selected catalytic removal of NOx

In this work, three synthesis methods including photo-chemical, precipitation and hydrothermal were applied for synthesizing CeO2/TiO2 catalysts, and the catalytic performance including photodegradation degrees for organic pollutant and ammonia selective catalytic reduction (NH3-SCR) for NO removal were investigated. It was found that the photo-chemical synthesized CeO2-TiO2-PC exhibited the best photodegradation ability for methylene blue (MB), which had the degradation ratio of 91.21% and was approximately 23.92% higher than that with the matrix of rutile TiO2. The formed Ce-Ti heterojunction enhanced the separation of e −/h + and further promoted the photocatalytic properties. Moreover, the CeO2-TiO2-PC, and the CeO2-TiO2-P which synthesized by the precipitation method showed better NH3-SCR properties than that of hydrothermal synthesized CeO2-TiO2-H below 300 °C, while the CeO2-TiO2-H owned an outstanding NH3-SCR performance above 300 °C. The difference on the NH3-SCR properties may be major attributed to the acid sites, pore structures and surface areas on the surface of different catalysts.

Monitoring ammonia slip from large-scale selective catalytic reduction (SCR) systems in combined heat and power generation applications with field effect gas sensors

Abstract. Following tightened regulations, selective catalytic reduction (SCR) of nitrogen oxides (NOx) by ammonia (NH3) has over the last couple of decades found wider adoption as a means of reducing NOx emissions from e.g. power production and district heating plants. As in the SCR process NH3 injected into the flue gas reacts with and reduces NOx to nitrogen (N2) and water (H2O) on the surface of a specific catalyst, the NH3 injection has to be dynamically adjusted to match both instant and long-term variations in flue gas nitrogen oxide concentration in order to minimize NOx and NH3 emissions. One possibility of realizing such NH3 dosing control would be the real-time monitoring and feedback of downstream flue gas NOx and NH3 concentrations to the NH3 injection control unit. In this study the sensing characteristics and performance of SiC-based Metal Oxide Semiconductor Field Effect Transistor (MOSFET) sensors with a structurally tailored gas-sensitive gate contact of iridium (Ir) for in situ NH3 monitoring downstream from the SCR catalyst in a combined heat and power (CHP) plant have therefore been investigated and evaluated. The sensor's NH3 sensitivity and selectivity as well as the cross-sensitivity to common flue gas components – oxygen (O2), water vapour (H2O), nitric oxide (NO), nitrogen dioxide (NO2), carbon monoxide (CO), and a model hydrocarbon, ethene (C2H4) – were thereby investigated for relevant concentration ranges under controlled conditions in the laboratory. While, at the prescribed sensor operation temperature of 300 ∘C, the influence of H2O, CO, and C2H4 on the sensor's NH3 concentration reading could be regarded as practically insignificant, a moderate cross-sensitivity was observed between NH3 and NO2 and, to a lesser extent, between NH3 / NO and NH3 / O2. As the NOx concentration downstream from the SCR catalyst under normal SCR and power plant operation is expected to be considerably smaller than the NH3 concentration whenever any appreciable ammonia slip occurs, the observed NH3 / NOx cross-sensitivities may, however, be of less practical significance for ammonia monitoring in real flue gases downstream from the SCR catalyst. Furthermore, if required, the small influence of O2 concentration variations on the sensor reading may also be compensated for by utilizing the signal from a commercially available oxygen sensor. Judging from in situ measurements performed in a combined heat and power plant, the structurally tailored Ir gate field effect sensors also exhibit good NH3 sensitivity over the relevant 0–40 ppm range when directly exposed to real flue gases, offering an accuracy of ±3 ppm as well as low sensor signal drift, the latter most likely to further improve with regular zero-point calibration and thereby make the Ir gate MOSFET ammonia sensor a promising alternative for cost-efficient real-time ammonia slip monitoring or SCR system control in heat and/or power production plants.

Inhibiting effect of C3H6 on the performance of Cu-SSZ-13 catalysts for NH3 selective catalytic reduction

Hydrocarbons (HCs) have been found to be a potential source of catalyst poisoning in ammonia selective catalytic reduction (NH3-SCR) of NOx. As one of the predominant constituents of hydrocarbons, propene (C3H6) was selected to investigate its inhibitory effect on Cu-SSZ-13 catalysts utilized in the NH3-SCR reaction. The results of standard SCR tests mixing C3H6 and NH3 showed that the NH3-SCR activity of Cu-SSZ-13 catalysts was inhibited in the range of 150–650 °C with the introduction of C3H6 and the NOx conversion was lowest in the presence of 2000 ppm C3H6. The competitive adsorption and NH3 oxidation activity were extensively studied. It was found that NH3 and C3H6 could both be stored on Brønsted acid sites and Cu sites. The introduction of C3H6 during NH3-TPD experiments caused an increase of weakly adsorbed NH3 on the weak Lewis acid sites and a decrease of adsorbed NH3 on the strong Lewis acid sites and Brønsted acid sites, confirming the existence of the competitive adsorption between NH3 and C3H6. Based on TPO experiments, C3H6 enhanced the NH3 oxidation activities in the temperature range of 250–650 °C, and coke deposition might be generated on the catalysts, causing the decline of NOx conversion during NH3-SCR with C3H6.

Revealing the crystal-plane effects of CuO during the NH3-SCR over CuO/TiO2 catalysts

Copper-based (Cu-based) catalysts have garnered significant attention for their potential in ammonia-selective catalytic reduction (NH3-SCR) of nitrogen oxides (NOx). However, the widespread industrial application of Cu cation-exchanged chabazite catalysts has been hindered by poor hydrothermal stability, expensive raw materials, and complicated preparation. As a result, copper oxide-based (CuO-based) catalysts have emerged as ideal candidates due to their low cost and facile preparation. Nevertheless, the performance of NH3-SCR catalysts is a significantly influenced by the crystal plane effect, which has been scarcely investigated in Cu oxide-based NH3-SCR catalysts. In this study, CuO with exposed {001} and {111} facets were synthesized and combined with titanium dioxide (TiO2) support to construct CuO/TiO2 composite NH3-SCR catalysts. These catalysts displayed divergent NOx removal performance due to the crystal-plane effects of CuO. Specifically, the proportion of Cu+ and surface-adsorbed oxygen (Oα) in CuO(111)/TiO2 catalyst was higher than that of CuO(001)/TiO2 catalyst, which could facilitate the NH3-SCR reactions. The NH3-TPD, NO-TPD, and DFT calculations demonstrated the better NH3 and NO adsorption capability of CuO(111)/TiO2 catalyst than that of CuO(001)/TiO2 catalyst. Furthermore, the more -NH2 and nitrate species in CuO(111)/TiO2 catalyst resulted in better NOx removal efficiency than CuO(001)/TiO2 catalyst. This study provides fundamental insights on the crystal-plane effect of CuO, which is critical for optimizing Cu oxide-based NH3-SCR catalysts.

Low-silica Cu-CHA Zeolite Enriched with Al Pairs Transcribed from Silicoaluminophosphate Seed: Synthesis and Ammonia Selective Catalytic Reduction Performance.

Cu-exchanged low-silica CHA zeolites (Si/Al ≤ 4) synthesized without organic templates are promising candidate catalysts for ammonia selective catalytic reduction of nitrogen oxides (NH3-SCR), but their practical application is restricted due to the low hydrothermal stability. Here, inspired by the transcription from duplex DNA to RNA, we synthesized Al pairs enriched low-silica CHA zeolite (CHA-SPAEI, Si/Al = 3.7) by using silicoaluminophosphate (SAPO) featured by strict alternation of -Al-O-P(Si)-O-Al-O- tetrahedra as seed. The proportion of Al pairs in CHA-SPAEI is 78%, which is much higher than that in the conventional low-silica CHA (CHA-LS, 52%). After hydrothermal ageing at 800 °C for 6 h, Cu-exchanged CHA-SPAEI shows NO conversion above 90% within 225-500 °C under a gas hourly space velocity of 200,000 h-1, which is much better than that of Cu-exchanged CHA-LS. The spatial close proximity of Al pairs in CHA-SPAEI is confirmed by the 27Al double-quantum single-quantum two-dimensional NMR analyses. The strict -P(Si)-O-Al-O-P(Si)-O- sequence in the fragments from the dissolution of SAPO seed promotes the Al pairs with the -Al-O-Si-O-Al-O- sequence via a transcription process. The utilization of aluminophosphate-based zeolites as seeds opens up a new avenue for the regulation of the Al distribution in zeolites.

Low‐silica Cu‐CHA Zeolite Enriched with Al Pairs Transcribed from Silicoaluminophosphate Seed: Synthesis and Ammonia Selective Catalytic Reduction Performance

AbstractCu‐exchanged low‐silica CHA zeolites (Si/Al≤4) synthesized without organic templates are promising candidate catalysts for ammonia selective catalytic reduction of nitrogen oxides (NH3‐SCR), but their practical application is restricted due to the low hydrothermal stability. Here, inspired by the transcription from duplex DNA to RNA, we synthesized Al pairs enriched low‐silica CHA zeolite (CHA‐SPAEI, Si/Al=3.7) by using silicoaluminophosphate (SAPO) featured by strict alternation of −Al−O−P(Si)−O−Al−O− tetrahedra as seed. The proportion of Al pairs in CHA−SPAEI is 78 %, which is much higher than that in the conventional low‐silica CHA (CHA‐LS, 52 %). After hydrothermal ageing at 800 °C for 6 h, Cu‐exchanged CHA‐SPAEI shows NO conversion above 90 % within 225–500 °C under a gas hourly space velocity of 200,000 h−1, which is much better than that of Cu‐exchanged CHA‐LS. The spatial close proximity of Al pairs in CHA‐SPAEI is confirmed by the 27Al double‐quantum single‐quantum two‐dimensional NMR analyses. The strict −P(Si)−O−Al−O−P(Si)−O‐ sequence in the fragments from the dissolution of SAPO seed promotes the Al pairs with the −Al−O−Si−O−Al−O− sequence via a transcription process. The utilization of aluminophosphate‐based zeolites as seeds opens up a new avenue for the regulation of the Al distribution in zeolites.

Comparision of NH3−SCR Activity over Cu‐Ce‐La/MCM‐49 and Cu‐Ce‐La/MCM‐22 Zeolites

AbstractThe addition of La onto Cu‐Ce modified MWW type zeolite (MCM‐49 and MCM‐22) catalysts were synthesized by ion exchange process and the effect of different support (MCM‐49 and MCM‐22) on the activity was also discussed for ammonia selective catalytic reduction of NOx (NH3−SCR). The addition of La can significantly improve the catalytic performance of Cu‐Ce/MCM‐49. Furthermore, the addition of La can also facilitate electron transfer by the cycle of oxidation of Cu2++Ce3+→Cu++Ce4+ for Cu‐Ce‐La/MCM‐49. The electron transfer is beneficial to “FAST SCR” in that it can promote the conversion of NO to NO2, thus improving denitrification performance. Moreover, La can also provide the excellent surface acidity, which is favorable for the generation of oxygen vacancies. Compared with Cu‐Ce‐La/MCM‐22, Cu‐Ce‐La/MCM‐49 catalyst exhibited better SCR activity within 200–450 °C on account of the good redox performance and the more Ce3+ content. In addition, Ce3+ can generate oxygen vacancies, thereby enhancing the catalytic performance. More than anything, Cu‐Ce‐La/MCM‐49 has excellent sulfur tolerance.

Amorphous FeOx–Mn0.1Oy catalyst with rich oxygen vacancies for ammonia selective catalytic reduction of nitrogen oxide at low temperatures

Amorphous materials have garnered extensive research interest in heterogeneous catalysis because of their high surface area and interconnected micro/mesopores. In this study, an amorphous metal oxides (FeOx-Mn0.1Oy) with large surface areas, sufficient oxygen vacancies, excellent redox properties is prepared for the ammonia selective catalytic reduction (NH3-SCR) of NOx. Benefits from the large surface area, this catalyst possess higher adsorption and activation ability for O2 and NO which further enhanced the catalytic activity at low temperatures (90–240 °C). The incorporation of Mn into FeOx species inhibits the crystallization of hematite, further resulting in an increase of the surface area and surface acid sites in the as-prepared catalyst. Furthermore, the number of oxygen vacancies increases by the incorporation of manganese, which reduces the apparent activation energy of hematite and enhances the redox property of the amorphous FeOx–MnOy catalyst. The reaction mechanism of this catalyst also has been proposed based on the result of in situ DRIFTs experiment results.

Facile one-pot synthesis of Fe-UZM-35 catalysts for ammonia selective catalytic reduction

Owing to the narrow crystallization field, the synthesis of the large-pore zeolite UZM-35 with MSE topology starting from amorphous reagents in the presence of dimethyldipropylammonium ions as an organic structure-directing agent is often non-reproducible. Here we report the synthesis of UZM-35 via an interzeolite conversion route using USY zeolites, as the sole source of Al and Si, and a small amount of previously synthesized UZM-35 as seed crystals. We also present the one-pot synthesis of Fe-UZM-35 with the best low-temperature NH3-SCR activity among the iron-exchanged zeolites reported so far. These synthesis routes showed high reproducibility, together with considerably faster crystallization kinetics (≤1.5 vs 7 days) compared to conventional UZM-35 synthesis. When the Fe loading level was properly adjusted, the NH3-SCR activity of one-pot-synthesized Fe-UZM-35 was found to be essentially the same as that of post-synthetically exchanged Fe-UZM-35 due to the similarity in the nature of their iron active sites.

Manganese-based catalysts supported on carbon xerogels for the selective catalytic reduction of NOx using a hollow fibre-based reactor

As a more compact, affordable and efficient alternative to traditional catalytic converters, catalytic hollow fibre-based reactors have significant potential in addressing the high nitrogen oxides (NOx) emission associated with the combustion of green ammonia. In this work, the performance of a series of manganese (Mn)-based catalysts supported on three different carbon xerogels during the ammonia-selective catalytic reduction (NH3-SCR) reaction was investigated in a packed bed reactor configuration under typical vehicle exhaust gas conditions. The best catalyst candidate Mn-CX, which was associated with the highest NO conversion (i.e. 24% at 225 °C) and highest nitrogen selectivity (i.e. 85% at 225 °C), was deposited in a 7-channelled hollow fibre substrate via a combined sol-gel and incipient wetness impregnation method. At 225 °C and 1 atm, the performance of the hollow fibre-based reactor was enhanced by a factor of four compared to the packed bed reactor (i.e. rO2= 3300 molO2∙m−3∙h−1∙gcat−1 and rO2= 810 molO2∙m−3∙h−1∙gcat−1). The superior performance of the hollow fibre-based reactor is attributable to the unique morphology of the hollow fibre substrate, which lends itself to minimised mass transfer limitations. The markedly improved performance of the hollow fibre-based reactor underlines its potential as a technically and economically feasible solution to mitigate the high NOx emissions associated with ammonia combustion. The identification of the catalytic hollow fibre-based reactor as a viable exhaust gas after-treatment technology for green ammonia-fuelled engines, addresses a significant barrier facing the adoption of green ammonia as a carbon-free, future fuel, thereby facilitating the transition to a decarbonised transport sector.

Characteristics analysis of hybrid ZSM-5 zeolite catalyst with nano La2Zr2O7 for ammonia-selective catalytic reduction (NH3-SCR) of NOx

The characteristical effects of ZSM-5 by doping La2Zr2O7 nanoparticle was investigated based on the application of ammonia-selective catalytic reduction (NH3-SCR). The hybrid ZSM-5 zeolite catalyst was synthesized by the Ion exchange and wet impregnation method to develop Cu-ZSM-5 and 5%, 10%, & 15% of La2Zr2O7 based Cu-ZSM-5. The characterization of hybrid catalyst was analysed by XRD, SEM, XPS, BET, FT-IR, & UVVis. From the analysis of the characteristics, La2Zr2O7 doped Cu-ZSM-5 hybrid zeolite catalyst exhibits excellent properties towards the application of ammonia-selective catalytic reduction (NH3-SCR) for the reduction of oxides of nitrogen to achieve EURO VI norms

Efficient one-pot synthesis of Cu-SAPO-34 catalysts for NH3-SCR of NOx

Cu-SAPO-34 shows high catalytic performance in ammonia selective catalytic reduction (NH3-SCR) of nitrogen oxides (NOx). Complex synthesis methods and environmental pollution limited the development of Cu-SAPO-34. Therefore, a new method for preparing Cu-SAPO-34 catalysts is proposed. A series of novel Cu-SAPO-34 catalysts have been synthesized by one-pot hydrothermal method. Aluminum phosphate was used as phosphorus and aluminum source to form the initial gel with the complex formed by Cu species and tetraethylenepentamine (TEPA). The novel Cu-SAPO-34 catalysts with different Cu content were prepared and characterized by XRD, UV–vis spectrum, H2-TPR, NH3-TPD and XPS. It is considered that there are Cu2+ species in the novel Cu-SAPO-34 catalysts and its proportion were analyzed. The three Cu-SAPO-34 catalysts with different Cu content have different NH3-SCR catalytic activity. And compared with conventional Cu-SAPO-34 catalyst with phosphoric acid as phosphorus source, one-pot synthesized Cu-SAPO-34 catalysts with different Cu content have more excellent NH3-SCR catalytic activity at high temperature.

Investigation of CNT and Zn doped Cu-SSZ-13 zeolite catalyst for ammonia selective catalytic reduction activity of NOx

Hybrid Cu-SSZ-13 zeolite catalyst are prepared and analyzed for NH3-SCR activity with different topologies in the present investigation. Cu-SSZ-13 was synthesized by ionexchange method, and hybrid Cu-SSZ-13 was synthesized by wet-impregnation method with three different molar ratios between Znx-CNTy as 1:5, 1:10, & 1:15 and maintained as 1:5 mass ratio between Znx-CNTy/Cu-SSZ-13 hybrid zeolite catalysts. The catalytic activity measured at a temperature window of 100˚C to 550˚C concludes hybrid Zn1- CNT10/Cu-SSZ-13 catalyst exhibits high NH3-SCR performance (100%) at a temperature of 180˚C to 475˚C and by anti-sulfur activity, it exhibits 80% NOx at 300˚C for 8hrs in the presence of SO2 gas in feed aid that addition of Zn species and CNTs influence Cu-SSZ13 in NH3-SCR activity finding them to be a better catalyst for NOx reduction.