NO-CH4-SCR Over Core-Shell MnH-Zeolite Composites

Abstract

Selective catalytic reduction of NO with methane (NO-CH4-SCR) in the presence of excess oxygen was investigated over the synthesized MnH-ZZs-n zeolite composite catalysts with FAU (as core) and BEA (as shell) topologies. XRD, SEM, and NH3-TPD technologies were employed to characterize the catalysts. It is found that the topological structure of the zeolite affected the catalytic properties and H2O/SO2 tolerances considerably. MnH-ZZs-n catalysts exhibited much higher NO-CH4-SCR activity than the physical mixture catalysts with comparable relative mass content of Y and Beta zeolites, particularly the ratio of Y and Beta at the range of 0.2–0.5 than the MnH-Beta catalysts with single topology. NH3-TPD results showed that one new type of strong acidic sites formed in H-ZZs-n and remained in MnH-ZZs-n resulted from the interaction between the Lewis and Brönsted acid sites under a particular environment. The special zeolite-zeolite structure with ion-exchanged Mn ions in the core-shell zeolite composite catalysts contributed to the novel NO-CH4-SCR properties.

Catalytic Glucose Conversion over Zeolitic Stannosilicates: A Comparative Study of Structural Properties

“…The pattern of Sn-MWW(3D) well matched with the typical 3D MWW structure, especially at 7.2, 7.9, 9.9, and 26.1° of 2θ corresponding to (100), (101), (102), and (301) reflections, respectively, with no impurities. In contrast, there was almost no characteristic X-ray peaks for the MWW structure in Sn-MWW(2D), which probably indicates the successful transformation of 3D to 2D MWW layers as reported in previous studies. , In addition, the XRD pattern of Sn-Beta(IT) exhibited the representative characteristic peaks of the Beta structure, i.e., 2θ = 7.8 and 22.47° corresponding to (101) and (302) reflections, respectively, without any impurities . This result indicates the complete interzeolite transformation of MWW into Beta.…”

“…28,29 In addition, the XRD pattern of Sn-Beta(IT) exhibited the representative characteristic peaks of the Beta structure, i.e., 2θ = 7.8 and 22.47°c orresponding to (101) and (302) reflections, respectively, without any impurities. 30 This result indicates the complete interzeolite transformation of MWW into Beta. Also, Sn-Beta(TD) showed characteristic peaks of the Beta structure, indicating that structural collapse did not occur during the dealumination and top-down Sn insertion of commercial Beta zeolite.…”

Exploring the Synthesis of Mesoporous In/H-β-NC Catalysts by Desilication Using CTAB Combined with NaOH and Its Application in CH4–SCR of NO

“…One gram of H-β zeolites was added to different volumes of 0.4 M NaOH solution (2, 4, 6, 8, and 10 mL) with 0.5 g of CTAB. The mixture was magnetically stirred for 20 min and then transferred to a reaction kettle for different etching times (3,6,9, and 12 h) under 85 °C. After cooling to room temperature, the mixture was filtered and washed until the pH value was about 7.…”

“…Over the past decade, CH 4 –SCR has gradually become a promising NO x removal technology because of the low cost and easier availability of CH 4 and avoidance of corrosion problems . Among many CH 4 –SCR catalysts, zeolites achieved the loading of various metals or nonmetals due to its rich pore structure and good hydrothermal stability and ion exchange level, so as to maintain high efficiency. , However, the catalysts need to resist poisoning of water vapor and SO 2 in real applications, and the cost of materials for the production of zeolite catalysts should be reduced as much as possible in the full-scale SCR reactors. In order to maintain the catalytic activity in unfavorable environments, lots of research has studied catalysts loaded with monometals, metal oxides, nonprecious metals or bimetals, etc.…”

Synthesis and Characterization of a Core-Shell Copolymer with Different Glass Transition Temperatures

“…Specifically, they can enhance the stability of crystal structures [62] and the responsiveness of sensors [63]. In addition, they increase the reaction activity of composite catalysts [64], have contributed to greener syntheses using natural plant products [65] and can also be very useful in magnetic applications [66]. It should be mentioned that core-shell polymers could play a significant role in effectively designing new multifunctional active materials for battery cells [67].…”