Catalytic Mechanism and Efficiency of Methane Oxidation by Hg(II) in Sulfuric Acid and Comparison to Radical Initiated Conditions

Abstract

Table of Contents SMD solvated (U)M06/def2-TZVPPD//(U)M06/cc-pwCVDZ-PP[aug-cc-pVDZ] xyz coordinates and energies (hartree) …………..

Pathways of Methane Transformation over Copper‐Exchanged Mordenite as Revealed by In Situ NMR and IR Spectroscopy

“…Thec ommon areas of research include methane dry reforming, [6,7] non-oxidative aromatization, [8,9] and, more recently, direct oxidation to methanol. [10][11][12][13] Thel atter direction has attracted considerable attention in the last decade after it was discovered that copper-exchanged zeolites are able to activate methane. [14][15][16][17] To utilize this unique feature for practical applications,achemical looping approach was suggested, implying cyclic exposure of the material, possessing redox properties,toanoxidant and to methane at different temperatures with the subsequent extraction of the oxidation products,t ypically by using water.…”

“…[14][15][16][17][18][19] Thea ctivation of copper-containing materials is carried out at above 673 K, while the reaction with methane and desorption of methanol requires lower temperatures to avoid over-oxidation. [10][11][12][13] Numerous copper-exchanged zeolites,i ncluding CuMFI, [14][15][16][17][18] CuMOR, [19][20][21][22][23][24][25][26] CuFAU, [27] CuMAZ, [28,29] and CuCHA, [30][31][32][33][34] were tested and revealed different methanol yields and selectivity per cycle.T he research targeting the achievement of the highest methanol productivity allowed to obtain the methanol productivity close to the theoretical limit. [35] However,i nm ost cases,i td oes not exceed % 100-150 mmol g À1 ,t hus accounting for % 0.2-0.3 mol(MeOH) mol À1 (Cu).…”

Pathways of Methane Transformation over Copper‐Exchanged Mordenite as Revealed by In Situ NMR and IR Spectroscopy

“…However, methane is the least active of all the alkanes, and its selective transformation to the desired product is challenging. The common areas of research include methane dry reforming, non‐oxidative aromatization, and, more recently, direct oxidation to methanol . The latter direction has attracted considerable attention in the last decade after it was discovered that copper‐exchanged zeolites are able to activate methane .…”

“…To utilize this unique feature for practical applications, a chemical looping approach was suggested, implying cyclic exposure of the material, possessing redox properties, to an oxidant and to methane at different temperatures with the subsequent extraction of the oxidation products, typically by using water . The activation of copper‐containing materials is carried out at above 673 K, while the reaction with methane and desorption of methanol requires lower temperatures to avoid over‐oxidation …”

Catalytic Methane Monofunctionalization by an Electrogenerated High-Valent Pd Intermediate

“… 13 This oxidant is attractive because it can be regenerated via aerobic combustion over a V 2 O 5 catalyst, 17 but the SO 3 /SO 2 couple possesses an even lower redox potential, E ° = 0.86 V ( Tables S14 and S15 ), further reducing the driving force for catalyst reoxidation. This low driving force, combined with the kinetic sluggishness of S–O bond cleavage, 18 , 19 makes catalyst reoxidation rate-limiting in nearly all methane functionalization cycles that employ SO 3 . 18 , 20 Clearly, practical methane functionalization schemes require the development of alternative approaches that provide for rapid catalyst reoxidation with a tunable driving force.…”