NO reduction by hydrocarbons and oxygenated compounds in O2 excess over a Pt/Al2O3 catalyst

Abstract

A 1% Pt/Al2O3 catalyst was prepared by wet impregnation of a -alumina with an aqueous solution of Pt(NH3)2(NO2)2. Metal particle sizes were centered around 20 nm. Twenty-seven reducers (12 hydrocarbons and 15 oxygenated compounds) were tested in NO reduction in O2 excess while keeping the same experimental conditions (inlet gas: 5%O2 and 5% H2O; space velocity: 14100 h -1 ; same temperature program from 150 to 600°C). To compare the reducers between them, two criteria were used: (i) the catalyst behavior at the maximum NOx conversion, and (ii) the efficiencies in NOx conversion and N2, N2O, NO2 production taking into account the temperature integrated performances of the reducers between 150 and 600°C. Among the hydrocarbons tested, cyclic C6 compounds show the highest efficiency in NOx conversion while, among the oxygenated compounds, diols and particularly butane-diols are the most efficient reducers. However, the selectivity to N2 is extremely dependent on the structure of the molecule. For instance, cyclohexadiene is very selective to N2 while aromatics are not. Moreover, the position of the two OH groups in diols can largely control the selectivity: butane-1,3-diol is very selective to N2 while butane-1,4-diol produces a great amount of N2O.

Study of SBA-15 supported catalysts for toluene and NO removal: the effect of promoters (Co, Ni, Mn, Ce)

“…It can be explained that toluene possessed a side chain compared to benzene. Other researchers have drawn similar conclusions [48,49].…”

NO x reduction by ethanol on Pd/zeolites-effect of oxygen

“…The weak acid sites of HZSM5 account 2.8% (Table 2) and are located at 294°C, desorbing 1.4 lmol/mg of pyridine, which is attributed to Lewis acids sites, in accordance with Li et al [13]. Requejo et al [18] studied the acidic properties of zeolites with different Si/Al ratios, using TPD of NH 3 and IR of pyridine.…”

“…At 200°C, the dominant pathway for ethanol oxidation is reaction with NO 2 , producing ethyl nitrite, which decomposes into a number of products, including N 2 O, which is stable under reaction conditions. Finally, NO reduction by oxygenated compounds was studied over Pt/Al 2 O 3 catalyst [13], which showed that primary alcohols are good reducers; however, for 50% conversion the temperature T 50°C was the less active under all other oxygenated reducers.…”

“…Some studies are reported in the literature for NO x reduction with ethanol as reductant agent [6][7][8][9][10][11][12][13]. Mello et al [6] studied the PdO-MoO 3 catalysts supported on Al 2 O 3 in this reaction and oxygenated compounds.…”

A Study of NO+CO Reaction over Various Supported Catalysts in the Presence of O2and H2O

“…For the catalytic reduction of NO x , reducing agents such as carbon monoxide (CO), hydrogen (H 2 ), ammonia (NH 3 ), urea ((NH 2 ) 2 CO) and different hydrocarbons are usually being employed. 1,2 Many supports such as alumina, titania, zirconia, ceria were usually used for dispersing the active phase for the elimination of nitrogen oxide. It is well known that supports play an important role in determining the nature and number of active sites, and consequently in the activity of the catalysts.…”