Lean-NOx reduction catalysis by metal-complex impregnated molecular sieves – Effect of ligands and metals

Paul, Partha P.; Heimrich, Martin J.; Miller, Michael A.

doi:10.1016/s0920-5861(98)00077-7

Cited by 7 publications

(3 citation statements)

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“…Copper is a metal known to show redox properties, and ions of copper have been introduced to mesoporous silica by means of ion exchange, impregnation, and grafting. [16][17][18][19] It has been reported that Cu-containing mesoporous silica can be synthesized directly by mixing copper complexes with a suitable organofunctional silicon alkoxide. 20,21 But it is difficult to introduce the divalent metal into the framework of tetravalent silicon without destroying the mesoporous structures, and indeed, the amount of copper that could be retained in a mesoporous silica framework is usually small.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, it is necessary to incorporate metal in the silicate framework to create active sites for catalytic interaction; metals such as Al, Ti, Cr, V, Sn, Co, Pd, Fe, Ga, Zr, and Mn have been respectively incorporated successfully in the mesoporous structures. ,− It has been demonstrated that transition metals can be incorporated in MCM-41 while retaining the uniform pore size of the mesoporous material. Copper is a metal known to show redox properties, and ions of copper have been introduced to mesoporous silica by means of ion exchange, impregnation, and grafting. − It has been reported that Cu-containing mesoporous silica can be synthesized directly by mixing copper complexes with a suitable organofunctional silicon alkoxide. , But it is difficult to introduce the divalent metal into the framework of tetravalent silicon without destroying the mesoporous structures, and indeed, the amount of copper that could be retained in a mesoporous silica framework is usually small. Wang et al reported that a copper amount of above 3.02 wt % would result in the collapse of the ordered mesoporous framework of MCM-41 .…”

Section: Introductionmentioning

confidence: 99%

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Novel Coassembly Route to Cu−SiO₂ MCM-41-like Mesoporous Materials

et al. 2004

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A series of mesostructured Cu-SiO2 composites have been synthesized with sodium metasilicate (Na2SiO3) and cuprammonia nitrate (Cu(NH3)4(NO3)2) respectively used as Si and Cu sources. The synthetic procedures were conducted at room temperature, and cetyltrimethylammonia bromide was used as a template. Under our experimental conditions, ordered mesoporous Cu-SiO2 composites could be obtained with a copper content up to 16.8 wt %. Average pore diameters (2.80-3.15 nm), wall thickness (1.30-2.20 nm), and specific surface area (1020-690 m2/g) are found to vary linearly with copper content (0-16.8 wt %). Results of thermal gravimetry-differential thermal analysis reveal the collapse temperature of the order structure starts at approximately 1250 K for mesoporous Cu-SiO2 with 16.8 wt % copper content. As indicated by the outcomes of inductively coupled plasma and X-ray photoelectron spectroscopy studies, copper is mainly incorporated inside the pore wall rather than embedded on the wall surface. Copper species strongly interact with silica, and calcination at high temperatures cannot cause phase separation between silica and copper oxide. Cu status in mesoporous Cu-SiO2 composites is similar to that in copper silicate in neighboring structures. Based on the results, a S+ I- I+ I- mechanism is proposed in which copper entities are surrounded by silicon species during synthesis of the mesostructured composite.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Novel Coassembly Route to Cu−SiO₂ MCM-41-like Mesoporous Materials

et al. 2004

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“…A bench-scale fixed-bed catalytic reactor system, as shown in Figure S3, was installed to investigate the removal efficiencies of SO 2 and NO by the SCDD process using H 2 S g as the reducing agent. 4 Å molecular sieves, which are widely used catalysts for the Claus process and SCR, , were used to catalyze H 2 S-SCDD. One gram of 4 Å molecular sieves (Na 12 [(AlO 2 ) 12 (SiO 2 ) 12 ]· x H 2 O, 20–40 mesh, Aladdin, Shanghai) was packed in the middle of a quartz tube reactor (1 cm in diameter, 35 cm in length).…”

Section: Materials and Methodsmentioning

confidence: 99%

Biological Sulfur Reduction To Generate H₂S As a Reducing Agent To Achieve Simultaneous Catalytic Removal of SO₂ and NO and Sulfur Recovery from Flue Gas

Sun

Zhou

et al. 2018

Environ. Sci. Technol.

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The conventional flue gas treatment technologies require high capital investments and chemical costs, which limit their application in industrial sectors. This study developed a sulfur-cycling technology to integrate sulfide production by biological sulfur reduction and simultaneous catalytic desulfurization and denitrification with HS (HS-SCDD) for flue gas treatment and sulfur recovery. In a packed bed reactor, high-rate sulfide production (1.63 ± 0.16 kg S/m-d) from biological sulfur reduction was achieved using organics in wastewater as electron donors at pH around 5.8. 93% of sulfide in wastewater was stripped out as HS, which can be a low-cost reducing agent in the HS-SCDD process. Over 90% of both SO and NO were removed by the HS-SCDD process under the test conditions, resulting in the formation of sulfur. 88% of the input S (HS and SO) were recovered as octasulfur with high purity. Besides partial recycling to produce biogenic sulfide, excessive sulfur can be obtained as a sellable product. The integrated sulfur-cycling technology is a chemical-saving and even profitable solution to the flue gas treatment in industrial sectors with wastewater available.

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