NH3 Selective Catalytic Reduction Research Articles

Preparation of Mn/TiO2 catalysts using recovered manganese from spent alkaline batteries for low-temperature NH3-SCR

Black mass (BM) from spent alkaline Zn-MnO2 batteries was used for the first time as a Mn source in the preparation of Mn/TiO2 catalysts for low-temperature NH3-selective catalytic reduction (SCR) of NOx. To recover Mn species and eliminate alkali and Zn species, BM powder underwent DI-water washing, followed by carbothermal reduction. The resulting slags were further dissolved in HNO3, loaded onto TiO2 particles with ball milling, and then subjected to calcination. Nearly 100% of Zn species were removed from the BM via carbothermal reduction at 950 °C for 4 h with 5.0 wt% activated carbon. The resulting catalyst, derived from the treated BM, achieved similar NOx conversion (97%) as the catalyst prepared using a reagent-grade Mn chemical at 160 °C but a higher NOx-to-N2 conversion rate at 78%. The promoted N2 selectivity was attributed to a high Mn4+/Ti ratio and the presence of impurities from BM, such as Fe3+ ions, which enhanced oxidation ability of the catalyst. Conversely, insufficient removal of Zn or carbon additives in the slags led to a decreased Mn concentration, an increased proportion of Mn2+/Mn3+ species, increased surface OH groups, and reduced oxidation ability on the surface, thus reducing NOx conversion and N2 selectivity.

Effect of vanadium and tungsten loading order on the denitration performance of F-doped V2O5-WO3/TiO2 catalysts.

F-doped V2O5-WO3/TiO2 catalyst has been confirmed to have excellent denitration activity at low temperatures. Since the V2O5-WO3/TiO2 catalyst is a structure-sensitive catalyst, the loading order of V2O5 and WO3 may affect its denitration performance. In this paper, a series of F-doped V2O5-WO3/TiO2 catalysts with different V2O5 and WO3 loading orders were synthesized to investigate the effect of denitration performance at low temperatures. It was found that the loading orders led to significant gaps in denitration performance in the range of 120-240 °C. The results indicated loading WO3 first better utilized the oxygen vacancies on the TiF carrier promoting the generation of reduced vanadium species. In addition, loading WO3 first facilitated the dispersion of V2O5 thus enhanced the NH3 adsorption capacity of VWTiF. In situ DRIFT verified the rapid reaction between NO2, nitrate, and nitrite species and adsorbed NH3 over the VWTiF, confirming that the NH3 selective catalytic reduction (NH3-SCR) reaction over VWTiF at 240 °C proceeded by the Langmuir-Hinshelwood (L-H) mechanism. This research established the constitutive relationship between the loading order of V2O5 and WO3 and the denitration performance of the F-doped VWTi catalyst providing insights into the catalyst design process.

Preparation of low-oxygen Ti–Al alloy by sustainable recovery of spent SCR catalyst

The wide spread application of NH3-selective catalytic reduction (NH3-SCR) process has led to the accumulation of large amounts of spent SCR catalyst. In this study, Al reduction–electromagnetic directional crystallization was used to recycle Ti, W, and V from spent SCR catalyst to prepare W- and V- containing TiAl alloys. The effects of the slag composition, reaction time, and amount of reductant added on the recovery ratios were investigated. The maximum recovery ratios of 94.16 %, 81.85 %, and 98.14 % for Ti, W, and V, respectively, were achieved at a reaction time of 60 min, addition of 45 wt.% Al, and CaO / Al2O3 ratio of 2 / 3. Furthermore, directional crystallization was performed on Ti–Al alloy under different atmospheres (99.99 % Ar or 90 % Ar + 10 % H2 gas) to investigate their effects on deoxygenation. 90 % Ar + 10 % H2 gas could effectively remove O from the Ti–Al alloys. Si and P impurities were enriched at the bottom of the alloy and Fe impurities at the top. The Ca and Mg impurities contents are approximately 50 and 10 ppmw, respectively, and S was removed difficultly. The total impurities content of the resulting W- and V- containing TiAl alloys were less than 1.85 %. The entire process is low-carbon and environmentally friendly.

Insight into the Alkali Resistance Mechanism of FeMoTiOx Catalysts for NH3 Selective Catalytic Reduction of NO: Self-Defense Effects of MoOx for Alkali Capture.

The deactivation of selective catalytic reduction (SCR) catalysts caused by alkali metal poisoning remains an insurmountable challenge. In this study, we examined the impact of Na poisoning on the performance of Fe and Mo co-doped TiO2 (FeaMobTiOx) catalysts in the SCR reaction and revealed the related alkali resistance mechanism. On the obtained Fe1Mo2.6TiOx catalyst, the synergistic catalytic effect of uniformly dispersed FeOx and MoOx species leads to remarkable catalytic activity, with over 90% NO conversion achieved in a wide temperature range of 210-410 °C. During the Na poisoning process, Na ions predominantly adsorb on the MoOx species, which exhibit stronger alkali resistance, effectively safeguarding the FeOx species. This preferential adsorption minimizes the negative effect of Na poisoning on Fe1Mo2.6TiOx. Moreover, Na poisoning has little influence on the Eley-Rideal reaction pathway involving adsorbed NHx reacting with gaseous NOx. After Na poisoning, the Lewis acid sites were deteriorated, while the abundant Brønsted acid sites ensured sufficient NHx adsorption. As a benefit from the self-defense effects of active MoOx species for alkali capture, FeaMobTiOx exhibits exceptional alkali resistance in the SCR reaction. This research provides valuable insights for the design of highly efficient and alkali-resistant SCR catalysts.

Enhancing resistance to CaO&PbO poisoning of CeO2/TiO2 NH3-SCR catalyst via hybrid with SO42−/ZrO2: Dual functions of SO42−/ZrO2

Catalyst deactivation caused by the co-poisoning of alkaline earth metals (CaO) and heavy metals (PbO) is still a problem in the NH3 selective catalytic reduction (SCR) of NOx in flue gas. In this work, a hybrid catalyst (Hybrid-CT) was being synthesized by grinding CeO2/TiO2 (CT) catalyst and SO42−/ZrO2 to evaluate the poisoning tolerance. It shown that Hybrid-CT exhibited a higher tolerance against CaO&PbO poisoning compared with CT. Under the co-poisoning of 2.5 wt% CaO and 2.5 wt% PbO, the NOx conversion of Hybrid-CT catalyst could approach to 100 % at 350 °C. Whereas, the NOx conversion of CT was only 66.3 % under the same condition. A series of characterizations suggested that the SO42−/ZrO2 could inhibit the CaO&PbO poisoning. Once the CaO&PbO present on the surface of Hybrid-CT catalyst, SO42− could convert CaO&PbO into CaSO4&PbSO4 with less toxic, which could protect the redox site and acid site of the CeO2/TiO2. Furthermore, the ZrO2 released from SO42−/ZrO2 could serve as a promoter, enhancing the acid performance of CeO2/TiO2 catalysts. Moreover, SO42−/ZrO2 could also reduce the passive effect of CaO&PbO on nitrate oxide. This work provides a simple and novel way to improve the resistance to CaO&PbO of Ce-based SCR catalysts.

Puffy hierarchical nanonet structured multifunctional membranes for NO degradation and ultrafine dust filtration

Multifunctional nanofibrous catalytic membranes are used for comprehensive treatment of fine particulate matter (PM) and toxic gaseous contaminants. However, the need for high purification efficiency with low resistance presents a unique challenge. Herein, a method of optimizing the morphology of manganese oxide (MnOx) on Zr-TiO2 (TZ) nanofiber membranes was developed to remove ultrafine PM and nitric oxide (NO) efficiently with relatively low pressure drops. After tailoring the hydrothermal solution properties, the MnO2 ultrafine nanowires (≈22 nm) and Mn3O4 nano-octahedra assembled with scaffold nanofibers formed dual-network structures with high gas permeabilities, superior redox properties, and abundant surface acidities. The resultant M2TZ (2-MnOx/Zr-TiO2) catalytic membranes exhibited exceptional NH3 selective catalytic reduction (NH3-SCR) activity (T90 = 215 °C) with a gas hourly space velocity of 75,000 h−1, as well as outstanding SO2 and H2O tolerance and long-term stability. Meanwhile, owing to the puffy hierarchical nanonet structure, the M2TZ catalytic membranes also show a high filtration efficiency of 99.99% for PM0.3 removal with a low air resistance of 125 Pa, high air permeability of 1259 m3 m−2 h−1 kPa−1, and satisfactory PM capture at 300 °C. This work may shed light on the design of advanced multifunctional membranes for air pollutant purification.

Effect of NO2 on N2 O production and NOx emission reduction in NH3 Selective Catalytic Reduction.

With the introduction of increasingly strict emission regulations, reducing nitrogen oxide (NOx ) emissions and nitrous oxide (N2 O) production from diesel engines have become the focus of research. At high temperature, the reaction of NO2 in the catalyst generates the intermediate product NH4 NO3 , which first crystallizes below 300 °C. These crystals tend to block the pores and inhibit the reaction. Subsequently, N2 O is produced through the decomposition of NH4 NO3 , leading to additional pollution. Therefore, the concentration of NO2 has a direct impact on both the NOx conversion efficiency and the generation of N2 O, requiring consideration of the optimal proportion of NO2 in SCR. Considering these two factors, it is concluded that the optimal amount of NO2 varies with temperature. To improve the NOx conversion rate of the Cu-SSZ-13 catalyst at low temperatures and reduce N2 O generation, the optimal NO2 ratio of the Cu-SSZ-13 catalyst under various operating conditions is studied using numerical simulations. As the temperature rises, the optimal NO2 /NOx ratio first increases and then decreases. Under the optimal NO2 /NOx ratio, the NOx conversion rate significantly increases, while N2 O generation decreases considerably. The optimal NO2 /NOx ratio also provides suggestions for the optimization of the DOC-DPF-DCR system.

Synergistic effect of oxygen-containing and nitrogen-containing groups on promoting low-temperature denitration over non-metallic carbon-based catalyst

Oxygen-containing and nitrogen-containing groups on the surface of non-metallic carbon-based catalysts have been regarded as active sites for NH3 selective catalytic reduction (NH3-SCR) of nitrogen oxides (NOx) at low temperature. In this study, series of AC-xO-yN catalysts were prepared via grafting oxygen-containing and/or nitrogen-containing groups on active carbon (AC). The activity test results showed that the denitration efficiency of AC-5O-0 N and AC-0O-4 N catalyst were only 20 and 44 % at a temperature of 120 °C and a GHSV of 4500 h−1, respectively, while the activity of the AC-5O-4 N catalysts reached 97 % at the same condition, indicating that the oxygen-containing and nitrogen-containing groups exhibited a superior synergistic effect in facilitating the low-temperature NH3-SCR denitration reaction. Characterization results revealed that the oxygen-containing groups (mainly carboxyl and lactone groups) contribute to NH3 adsorption and activation, while the nitrogen-containing groups (especially pyridine nitrogen groups) could promote NO adsorption and oxidation. The co-existence of oxygen-containing and nitrogen-containing groups can synergistically advance the low-temperature NH3-SCR denitration reaction on the surface of the AC catalyst via a fast SCR route. This work might provide insight into designing and preparing non-metallic carbon-based catalysts with high denitration performance.

Inhibition of Cu-SSZ-13 for NH3 Selective Catalytic Reduction by K/Na Poisoning

Inhibition of Cu-SSZ-13 for NH3 Selective Catalytic Reduction by K/Na Poisoning

Highly dispersed V2O5-WO3 in modified morphology of flower-like TiO2 for NH3-selective catalytic reduction over wide temperatures

NOX, a first-class carcinogen, and secondary particulate matter are produced in Various industrial processes form stationary sources such as steel mills and thermal power plants. Selective catalytic reduction is a method of repeatedly exposing used as V2O5-WO3/TiO2 to high temperatures by used NH3 reduction agent to N2 and H2O. Consequently, the catalytic performance decreases during the aggregation of transition metal and support, and industries need catalysts that react in a wide temperature range. In this study, flower-type TiO2 (FL-Ti) that changes the morphology of TiO2 was synthesized through hydrothermal method, anatase TiO2 with a similar specific surface area to commercial TiO2 was synthesized, and the dispersibility of transition metals was increased. Synthesis was conducted by changing the ratio of commercial TiO2 to FL-Ti to increase economic efficiency and reduce aggregation of transition metal and TiO2, thus resulting in their high dispersion. The presence of Ti3+ in FL-Ti increased the hydroxyl group owing to increased Ti-O bonds and the V4+ ratio, which positively influenced the catalyst at low temperatures. The catalyst with added FL-Ti reacted with the Eley-Rideal mechanism. Additionally, NOX conversion and N2 selectivity were approximately 93–99% at temperatures ranging from 250–420 ℃.

Conversion of NOx over Aluminosilicate Cu-CHA Zeolite Catalysts Synthesized Free of Organic Structure-Directing Agents

Cu-CHA zeolites have proven to be effective for NOx reduction, but a drawback in using CHA zeolites is the cost associated with using expensive organic structure-directing agents. To overcome this drawback, we are reporting here the synthesis of Cu-CHA zeolite catalysts in both their NH4-form as well as K-form that do not require the use of organic structure-directing agents. After comprehensive characterization by XRF, XRD, 27Al NMR spectroscopy, FE-SEM, SEM/EDS, N2-adsorption/desorption, NH3-TPD, H2-TPR, and XPS, the zeolite catalysts were tested for NOx conversion by NH3-selective catalytic reduction (NH3-SCR). Cu-NH4-CHA zeolite catalysts exhibited remarkable activity and thermal stability over a wide temperature window, outperforming their counterpart K-forms. Among the NH4-forms of CHA zeolite catalysts, the 0.1 M Cu-NH4-CHA showed the best catalytic performance, achieving 50% NOx conversion at a temperature as low as 192 °C, and reaching full conversion of NOx at 261 °C. These Cu-based CHA zeolite catalysts are promising thanks to their environmentally friendly synthesis and offer the opportunity of maximizing DeNOx strategies in applications for NOx pollution abatement.

Mechanistic Insight into the Promotion of the Low-Temperature NH3-SCR Activity over NiMnFeOx LDO Catalysts: A Combined Experimental and DFT Study.

Mn-based catalysts have attracted much attention in the field of the low-temperature NH3 selective catalytic reduction (NH3-SCR) of NO. However, their poor SO2 resistance, low N2 selectivity, and narrow operation window limit the industrial application of Mn-based oxide catalysts. In this work, NiMnFeOx catalysts were prepared by the layered double hydroxide (LDH)-derived oxide method, and the optimized Ni0.5Mn0.5Fe0.5Ox catalyst had the best denitration activity, excellent N2 selectivity, a wider active temperature range (100-250 °C), higher thermal stability, and better H2O and/or SO2 resistance. A transient reaction revealed that Ni0.5Mn0.5Fe0.5Ox inhibited the NH3 + O2 + NOx pathway to generate N2O, which may be the main reason for its improved N2 selectivity. Combining experimental measurements and density functional theory (DFT) calculations, we elucidated at the atomic level that sulfated NiMnFeOx (111) induces the adjustment of the acidity/basicity of up and down spins and the ligand field reconfiguration of the Mn sites, which improves the overall reactivity of NiMnFeOx catalysts. This work provides atomic-level insights into the promotion of NH3-SCR activity by NiMnFeOx composite oxides, which are important for the practical design of future low-temperature SCR technologies.

Low temperature NH3 selective catalytic reduction of NOx over CeOx-biochar catalyst prepared by air oxidation

A highly efficient CeOx-BC0.6 (BC: biochar. 0.6: mass ratio of Ce/(BC + Ce)) catalyst was prepared by air oxidation for low temperature NH3 selective catalytic reduction of NOx. The catalytic performance, characterization and reaction mechanism of the CeOx-BC0.6 were investigated. The results showed that NOx conversion and N2 selectivity of CeOx-BC0.6 catalyst obtained by calcining in air were above 90 % at 150–300 °C and 100,000 h−1. The surface oxygen groups, acid sites and oxygen vacancies were generated by air oxidation treatment, which promoted the adsorption and activation of reactants. NH3 and NOx were adsorbed on the catalyst surface in the form of NH4+, NH3+, nitrite and nitrate adspecies. The redox cycles of ketonic carbonyl/phenol (CO/C–OH) pairs and Ce4+/Ce3+ pairs were responsible for the activation of NH3 and NOx. NH2NO and NH4NO2 were the main active intermediates. The reaction of NH3 selective catalytic reduction of NOx over CeOx-BC0.6 mainly followed Eley-Rideal mechanism. These results will promote the understanding of mechanism of NH3 selective catalytic reduction of NOx for biochar-based catalyst prepared by air oxidation.

Gas-expanded pore MOF derived Sm/MnOx catalysts enable ultralow-temperature selective catalytic reduction of NOx

Employing physical manipulation in macroscopic manner to achieve fine-tuning of solid mutiple-component interface and then improving of corresponding catalytic efficiency was still highly desirable but challengeable topic in design of advanced heterogeneous catalysts. Herein, a physical CO2 gas-intermediate pore-expanding strategy was deliberately integrated in the preparation of Mn-MOF precursor to facilitate the incorporation of Sm, which was employed to obtain derived Sm/MnOx catalyst with fine-tuned catalytic interface for NH3-Selective Catalytic Reduction (NH3-SCR) of NOx. Based on in-situ DRIFT analyses, DFT calculations was integrated to image that more sites exposed on the compact Sm-O-Mn interface would greatly lower the adsorption energies (Eads) for reactant and reaction intermediate. On such fine-tuned Sm-O-Mn interface, a distinct catalytic performance for NH3-SCR of NOx with 95% conversion was achieved at ultra-low temperature of 50 °C, which could be ranged in the best level compared to literature reports.

Time-resolved in situ/operando infrared spectroscopy of Cu-supported zeolite X catalyst during NH3–SCR of NO: A modulated excitation study

Zeolite X was used as support of copper catalyst (Cu/X) for selective catalytic reduction (SCR) of nitrogen oxide (NO) with ammonia (NH3). Modulated excitation in situ/operando infrared (IR) spectroscopy and phase-sensitive detection (PSD) were applied to study the reaction intermediates that formed on the Cu/X during transient experiments. Changing the gas concentration to periodically create unsteady conditions enabled the selective extraction of the dynamic species that were directly involved in the reaction. The IR results showed that only Lewis acid sites (LX) existed on zeolite X,and Brønsted acid sites (B) and extra Lewis acid sites (LCu) were generated after Cu loading. The transient experiment results indicated that the SCR reactions on Cu/X obeys the Eley − Rideal (E − R) mechanism, in which NH3 is first adsorbed on the LX and LCu sites (LX–NH3, LCu–NH3) and then moved to the B sites (B–NH3), where it reacted with gas-phase NO to form NH2NO intermediate, which finally decomposed into N2 and H2O. Moreover, it is found that the NH3 adsorbed on LCu and B sites exhibits stronger reactivity than that on the LX sites.

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.

A novel high activity MnXFe3−XO4 spinel catalyst for selective catalytic reduction of NO using NH3 prepared by a short process from natural minerals for low-temperature sintering flue gas: Effect of X value on catalytic mechanism

The process of smelting and purifying the catalyst precursor salt from minerals is extremely complex, which directly leads to high catalyst costs and serious secondary pollution. In order to achieve energy saving and emission reduction in the catalyst preparation process, in-situ synthesis of catalyst materials from natural minerals is a new research direction. In this study, we firstly explored the optimal X value of MnXFe3-XO4 for the NH3 selective catalytic reduction of NO (NH3-SCR) reaction, i.e., the Mn, Fe ratio, and then prepared a novel highly active mineral-based pure phase MnXFe3-XO4 spinel NH3-SCR catalyst by natural ferromanganese ore fines with iron-red fines (Fe2O3) allotment through in situ solid-phase synthesis and magnetic separation methods according to this ratio. The results show that the X value of 1.5 (Mn1.5Fe1.5O4) is the best for NH3-SCR reaction. Mn1.5Fe1.5O4 nano-particles (201 nm) has nearly 100 % NO conversion (with 5 % H2O(g)) at 125–300 °C. The combination of characterizations and density functional theory (DFT) calculation shows that the catalytic process of Eley-Rideal (E-R) dehydrogenation is enhanced at both the active site Mn site and Fe site, which is a key factor in the acceleration of the NH3-SCR reaction with increasing X value at the MnXFe3-XO4 surface.

Insight into the construction of multi-cavity micro-mesoporous SSZ-13: Dissolution, Al backfilling and framework reconstruction

The alkali leaching post-treatment method is a simple, economical and general route for introducing mesopores into SSZ-13, while the existing studies have rarely addressed the Al behavior between solution and zeolites framework during the alkali treatment. In this paper, a series of multi-cavity micro-mesoporous SSZ-13 were successfully prepared by using the alkali leaching post-treatment method at various treatment time. Extensive characterization illustrated that Al backfilling and zeolite framework reconstruction also existed during the NaOH treatment, besides the destruction of the zeolite framework due to the dissolution of Si and Al at the beginning of the reaction, and Al was preferentially backfilled into eight-membered ring (8 MR) to repair the zeolite framework and then filled into six-membered ring (6 MR) to reconstruct the zeolite framework. Concurrently, the amount of Brønsted acid (B acid) showed a decreasing-increasing-stabilizing trend during the progress. The catalytic activity and hydrothermal stability tests confirmed that multi-cavity micro-mesoporous SSZ-13 showed excellent catalytic activity for NH3 selective catalytic reduction (NH3-SCR) and good hydrothermal stability. This study provided basic guidance for the optimal design of the post-treatment alkali leaching route, which was highly significant for the development of hierarchically porous zeolites.

Deactivation induced by metal sulfate over MnCeOx catalyst in NH3-SCR reaction at low temperature

Sulfate adsorption is one of the factors that cause the poisoning of catalyst in the low-temperature NH3 selective catalytic reduction reaction (NH3-SCR). In this paper, by controlling the co-adsorption time of SO2 and O2 at 150 °C, a range of sulfated MnCeOx catalysts with different contents of metal sulfate species were prepared to reveal the influence of metal sulfate species content on the catalytic performances and reaction mechanisms at low temperature. The catalytic activity below 250 °C rapidly decreases with increasing metal sulfate species content. The results of characterizations shed light on the reduction of specific surface area, Mn4+ and Ce3+ content, and redox ability of MnCeOx owing to the formation of metal sulfate species. Further experiments reveal that metal sulfate species preferentially absorb on MnOx domains rather than on CeO2 domains, and the adsorbed metal sulfate species can suppress the Eley-Rideal and the Langmuir–Hinshelwood reaction mechanisms over the sulfated MnCeOx. All the above results are detrimental to the activity of sulfated MnCeOx in the low-temperature NH3-SCR reaction.

Boosting Water-Resistance Ability on a PTFE Modified Ti-OMS-2 Catalyst for Low-Temperature NH3-SCR Reaction

Manganese-based catalysts are considered as ideal alternative catalysts for NH3 selective catalytic reduction of NOx due to their excellent denitrification performance, but their weak water resistance limits industrial applications. To improve the water resistance of low-temperature Mn-based catalysts in the NH3-SCR reaction, a Ti-OMS-2 (titanium-manganese oxide octahedral molecular sieve) catalyst was prepared by the hydrothermal method, and polytetrafluoroethylene (PTFE) powder was methodically introduced on the catalyst surface by the impregnation method. Importantly, the introduction of PTFE on the Ti-OMS-2 catalyst surface could effectively inhibit the adsorption of water molecules and reduce the probability of active species being consumed. Thus, it showed better catalytic activity and water resistance. The activity of the Ti-OMS-2-20%-PTFE catalyst could reach more than 80% when water vapor was introduced at 180 °C. More importantly, the Ti-OMS-2-20%-PTFE catalyst did not readily bind the active species (Mn4+ and Oads) and maintained the adsorption and activation of NH3 species. Moreover, it was easy for PTFE to form a weak surface hydrophobic layer on the Ti-OMS-2 catalyst surface that could effectively inhibit water toxicity. Therefore, this work provided a reasonable idea and experimental accumulation for the industrial application of Mn-based catalysts.