Nitrosylic complexes in Ag(I)–ZSM-5: a comparison with Cu(I)–ZSM-5

Bordiga, Silvia; Lamberti, Carlo; Palomino, Gemma Turnes; Geobaldo, Francesco; Arduino, D; Zecchina, Adriano

doi:10.1016/s1387-1811(99)00017-7

Cited by 25 publications

(23 citation statements)

References 30 publications

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“…[75][76][77][78] All these species were typically present on the surface of Cu due to the oxidizing ability of Cu during SCR reactions that produced these species in the presence of NH 3 , NO, or a mixture of both, and contributed to the deactivation of the surface. 56,57,79 This data agree with those obtained from gas phase studies with regard to the lower amount of NH 3 production and the presence of NO 2 in the gas phase spectra. The peak at 2206 cm -1 in Figure 6b corresponds to the NCO asymmetric stretch for adsorbed HNCO that formed from urea decomposition.…”

Section: R a F Tsupporting

confidence: 88%

Mechanistic studies on the conversion of NO gas on urea-iron and copper metal organic frameworks at low temperature conditions: in situ infrared spectroscopy and Monte Carlo investigations

2021

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Nitrogen oxides (NOx) emissions from high temperature combustion processes under fuel-lean conditions continue to be a challenge for the energy industry. Selective catalytic reduction (SCR) has been possible with metal oxides and zeolites. There is still the need to identify catalytic materials that are efficient in reducing NOx to environmentally benign nitrogen gas at temperatures lower than 200°C. Metal-organic frameworks (MOFs) emerged as a class of highly porous materials with unique physical and chemical properties. This study is motivated by the lack of systematic investigations on SCR using MOFs under industrially-relevant conditions. Here, we investigate the extent of NO conversion with two commercially-available MOFs; Basolite F300 (Fe-BTC) and HKUST-1 (Cu-BTC), mixed with solid urea as a source for the reductant, ammonia gas. For comparison, experiments were also conducted using cobalt ferrite (CoFe2O4) as a non-porous counterpart to relate its reactivity to those obtained from MOFs. Fourier-transform infrared spectroscopy (FTIR) was utilized to identify gas and surface species the temperature range 115 -180°C. Computational analysis was performed using Monte Carlo (MC) simulations to quantify adsorption energies of different surface species. The results show that the rate of ammonia production from the in situ solid urea decomposition was higher using CoFe2O4 than Fe-BTC and Cu-BTC, and that there is very limited conversion of NO on the mixed solid urea-MOF systems due to site blocking. The main conclusions from this study is that MOFs have limited abilities in converting NO under low temperature conditions, and that surface regeneration requires additional experimental steps.

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Section: R a F Tsupporting

confidence: 88%

Mechanistic studies on the conversion of NO gas on urea-iron and copper metal organic frameworks at low temperature conditions: in situ infrared spectroscopy and Monte Carlo investigations

2021

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“…On the contrary, it is worth noting the large deviation of the points corresponding to Cr 2+ species grafted on silica, 488 a system where covalent contributions play a certain role in both Cr 2+ Á Á ÁCO and Cr 2+ Á Á ÁH 2 interactions. Investigated systems are as follows: Li + -, Na + -and K + -FER, 490 Na + -and K + -ETS-10, 382 Cu + -ZSM-5, 378,385 Cu + -Y, 384 Cu + -b, 161 Cu + -SSZ-13, 161 Ag + -ZSM-5, 334,335 and Fe 2+ -ZSM-5, 249 and, for comparison, TiO 2 , 491 ZrO 2 , 491 MgO, 39 NiO, 492 a-Fe 2 O 3 , 21 Cu 2 O/SiO 2 , 423 NaCl, 493 CuCl/g-Al 2 O 3 , 431 Cr 2+ /SiO 2 , 488 and CPO-27-Ni. 11b.…”

Section: Charge-balancing Extraframework Cationsmentioning

confidence: 99%

“…11b. Investigated systems are as follows: Li + -, Na + -and K + -FER, 490 Na + -and K + -ETS-10, 382 Cu + -ZSM-5, 378,385 Cu + -Y, 384 Cu + -b, 161 Cu + -SSZ-13, 161 Ag + -ZSM-5, 334,335 and Fe 2+ -ZSM-5, 249 and, for comparison, TiO 2 , 491 ZrO 2 , 491 MgO, 39 NiO, 492 a-Fe 2 O 3 , 21 Cu 2 O/SiO 2 , 423 NaCl, 493 CuCl/g-Al 2 O 3 , 431 Cr 2+ /SiO 2 , 488 and CPO-27-Ni. 494,495 A linear dependence has been obtained for ñ(CO) vs. ñ(NO) data collected for alkali-metal-exchanged ferrierite (red squares in Fig.…”

Section: Charge-balancing Extraframework Cationsmentioning

confidence: 99%

Probing zeolites by vibrational spectroscopies

et al. 2015

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This review addresses the most relevant aspects of vibrational spectroscopies (IR, Raman and INS) applied to zeolites and zeotype materials. Surface Brønsted and Lewis acidity and surface basicity are treated in detail. The role of probe molecules and the relevance of tuning both the proton affinity and the steric hindrance of the probe to fully understand and map the complex site population present inside microporous materials are critically discussed. A detailed description of the methods needed to precisely determine the IR absorption coefficients is given, making IR a quantitative technique. The thermodynamic parameters of the adsorption process that can be extracted from a variable-temperature IR study are described. Finally, cutting-edge space- and time-resolved experiments are reviewed. All aspects are discussed by reporting relevant examples. When available, the theoretical literature related to the reviewed experimental results is reported to support the interpretation of the vibrational spectra on an atomic level.

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“…In the figure the experimental results where both probes have been used on the same samples are reported. Investigated samples are: Na + -and K + -ETS-10, 79 TiO 2 , 506 ZrO 2 , 506 MgO, 14 NaCl, 182 Cu + -ZSM-5, 208,215 Cu + -Y, 213 Ag + -ZSM-5 235,507 and Cr 2+ /SiO 2 , 16 Fe 2+ ZSM-5, 87 NiO, 10 CPO-27-Ni, 268,508 a-Fe 2 O 3 , 99 Cu 2 O/SiO 2 , 226 CuCl/g-Al 2 O 3 . 391 A very good linear dependence has been obtained for the data collected on alkali-metal exchanged ferrierite (red squares), where the anionic environment is exactly the same for the three investigated cations.…”

Section: Nitric Oxide 41 General Consideration On the Metal-no Intera...mentioning

confidence: 99%

“…The interaction of NO with Ag + in Ag + -ZSM-5 is weak, as indicated by the reversible character and the small shift of ñ(NO) with respect to NO gas frequency. 236,507 The positive shift Dñ(NO) = +8 cm À1 is indicative of an interaction with prevailing electrostatic character and weak contribution of d-p overlap forces. Among all d-metals summarized in Fig.…”

Section: Interaction Of No With Ni 2+ Centersmentioning

confidence: 99%

Probing the surfaces of heterogeneous catalysts by in situ IR spectroscopy

et al. 2010

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This critical review describes the reactivity of heterogeneous catalysts from the point of view of four simple, but essential for Chemistry, molecules (namely dihydrogen, carbon monoxide, nitrogen monoxide and ethylene) that are considered as probes or as reactants in combination with "in situ" controlled temperature and pressure Infrared spectroscopy. The fundamental properties of H(2), CO, NO and C(2)H(4) are shortly described in order to justify their different behaviour in respect of isolated sites in different environments, extended surfaces, clusters, crystalline or amorphous materials. The description is given by considering some "key studies" and trying to evidence similarities and differences among surfaces and probes (572 references).

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Nitrosylic complexes in Ag(I)–ZSM-5: a comparison with Cu(I)–ZSM-5

Cited by 25 publications

References 30 publications

Mechanistic studies on the conversion of NO gas on urea-iron and copper metal organic frameworks at low temperature conditions: in situ infrared spectroscopy and Monte Carlo investigations

Mechanistic studies on the conversion of NO gas on urea-iron and copper metal organic frameworks at low temperature conditions: in situ infrared spectroscopy and Monte Carlo investigations

Probing zeolites by vibrational spectroscopies

Probing the surfaces of heterogeneous catalysts by in situ IR spectroscopy

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