Ethane selective reduction

Hydrogenation. Acetylene can be hydrogenated to ethylene and ethane. The reduction of acetylene occurs in an ammoniacal solution of chromous chloride (20) or in a solution of chromous salts in H2SO4 (20). The selective catalytic hydrogenation of acetylene to ethylene, which proceeds... 

It was found, that also Ru and Os colloids can act as catalysts for the photoreduction of carbon dioxide to methane [94, 95]. [Ru(bpy)3]2+ plays a role of a photosensitizer, triethanolamine (TEOA) works as an electron donor, while bipyridinium electron relays (R2+) mediate the electron transfer process. The production of hydrogen, methane, and small amounts of ethylene may be observed in such a system (Figure 21.1). Excited [Ru(bpy)3]2+ is oxidized by bipyridinium salts, whereas formed [Ru(bpy)3]3+ is reduced back to [Ru(bpy)3]2+ by TEOA. The reduced bipyridinium salt R + reduces hydrogen and C02 in the presence of metal colloids. Recombination of surface-bound H atoms competes with a multi-electron C02 reduction. More selective reduction of C02 to CH4, ethylene, and ethane was obtained using ruthenium(II)-trisbipyrazine, [Ru(bpz)3]2+/TEOA/Ru colloid system. The elimination of hydrogen evolution is thought to be caused by a kinetic barrier towards H2 evolution in the presence of [Ru(bpz)3]2+ and noble metal catalysts [96]. 

The electroreduction of CO2 using a Cu cathode leads preferentially to methane and ethane [584, 585]. The selectivity is dependent on the cationic species as well as on the HCOs" concentration [586]. Hydrogen evolution prevails over CO2 reduction in a Li+ electrolyte, whereas CO2 reduction proceeds favorably in Na+, K+, and Cs+ solutions [587-589]. 

Burch, R. and Scire, S. Selective catalytic reduction of nitric oxide with ethane and methane on some metal exchanged ZSM-5 zeolites. Appl. Catal, B Environmental,... 

Whilst many studies of metal-coated Ti02 powders and colloids for the reduction of C02 have been reported [135], Ti02 alone seems ineffective for C02 reduction. Adachi et al. was able to reduce C02 to methane, ethane, and ethylene in aqueous solution using Cu-loaded Ti02 powders [136]. Likewise, others were able to produce methanol almost selectively with both Rh- and W03-doped Ti02 powders. The... 

Ethene and ethane account for 80% of the mass of the hydrocarbons identified as products. Trace amounts of methane and acetylene are also produced (Orth and Gillham, 1996). The reduction of PCE forms cis-1,2-dichloroethylene (DCE), frans-l,2-DCE, 1,1-DCE, vinyl chloride, ethylene, dichloroacetylene, acetylene, ethene, ethane, chloroacetylene, methane, and several alkenes ranging from C3 to C6. The trace amounts of dichloro-ethylene and vinyl chloride formed during the reduction of PCE and TCE are further reduced (Burris et al., 1995). Reaction rates vary with substrate, chemical, and microbiological conditions. Selected f1/2 values are provided in Table 13.3. 

These observations are consistent with those of other UV-vis experiments (Puurunen and Weckhuysen, 2002 Puurunen et al., 2001). Raman spectroscopy of a working alumina-supported vanadia catalyst, showed that the surface population ratio of polymeric-to-isolated vanadia species decreased during reduction (as indicated by a relative loss in intensity of the 1009-cm 1 band relative to that of the 1017-cm 1 band), whereas the total activity and selectivity in propane ODF1 essentially remained unaffected (Garcia-Cortez and Banares, 2002). This result suggested that the active sites for ODH of propane and of ethane on alumina-supported vanadia should be isolated surface vanadia sites, whereas other arrangements of vanadium sites such as polymeric species did not seem to be crucial. 

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