deNO x reduction by methanol over Co/alumina

Abstract

The temperature window of NO x consumption lies between 140 and 500°C. The 0.5 wt%Co/Al 2 O 3 catalyst exhibits a total consumption of NO x between 300 and 350°C at a space velocity of 50 000 h )1 . The presence of acetonitrile and methylnitrite can explain the difference between N 2 formation and NO x consumption at T < 400°C. The Co 2+ , in octahedral site, has been shown to coordinate two NO molecules.

Catalysis Science of Bulk Mixed Oxides

“…In addition to the above physical characterization techniques, the outermost surface of bulk mixed metal oxides can also be chemically probed, since molecules cannot diffuse into the bulk of mixed oxides. Finding the proper molecule for metal oxides has been a challenge, since chemical methods employed for quantitatively determining the number of catalytic active sites on metal catalysts (e.g., chemisorption of CO, H 2 , and O 2 ) have not been found to be feasible with metal oxides. − Methanol, as well as some other small alcohols, has been found to be a “smart” chemical probe molecule that can quantify the number of catalytic active sites, nature of the sites (redox, basic or acidic), oxidation states of the sites, and their chemical reactivity (kinetics and selectivity). − Methanol-IR spectroscopic chemisorption measurements can distinguish among surface methoxy (M-OCH 3 ) species coordinated to different surface cation sites and, thereby, provides direct information about the surface coordination sites and surface composition. ,, Methanol-temperature programmed surface reaction (TPSR) spectroscopy also quantifies the number of catalytic active sites as well as provides information about their chemical and electronic properties (selectivity (redox, basic, or acidic), kinetics, and oxidation states). − …”

DME as Reductant for Continuous Lean Reduction of NO x over ZSM-5 Catalysts

“…According to Park et al a good SCR-catalyst needs three different functions: (i) ability to oxidize NO to NO 2 , (ii) activation of hydrocarbon, and (iii) reduction of NO x to N 2 and oxidation to CO 2 [16]. The ability to oxidize NO to NO 2 (function i) is likely less important for DME-SCR, since NO is oxidized to NO 2 in the gas phase.…”