Honeycomb Reactor Washcoated with Mordenite Type Zeolite Catalysts for the Reduction of NO_x by NH₃

Abstract

A low pressure drop reactor was prepared by washcoating Cu ion-exchanged mordenite on a honeycomb. The reactor configuration including reaction conditions was experimentally optimized both for low-pressure drop and for high catalytic activity of the honeycomb reactor. Over 90% of NO conversion was achieved by both Cu ion-exchanged synthetic zeolite (CuHM) and natural zeolite (CuNZA). The pressure drops due to honeycomb reactors were low enough to meet the constraint of the pressure drop (5 in. of H2O) for its application to a utility boiler. A mathematical model based on fluid flow, reaction kinetics, and pressure drop was derived for the design of the reactor, and then the reactor was simulated to examine the effects of operating conditions on NO conversion. Finally, the sulfur tolerance of the honeycomb reactor developed in this work has also been investigated.

High hydrothermal stability of Cu–SAPO-34 catalysts for the NH3-SCR of NOx

“…S3). Zamadics et al [35] reported that EPR signal (g// = 2.381, A = 143 G) in hydrated Cu-SAPO-34 could be assigned to Cu 2+ located in the sixmembered-ring as a complex Cu(O F ) 3 (H 2 O) 3 . The similar EPR signals for Cu-CHA catalysts reported by others [26,37] were also suggested to be this type of species, such as g// = 2.39 with A = 111 G and g// = 2.394 with A = 131 G. Thus, this EPR signal should be due to the isolated Cu 2+ located in the six-membered-ring for hydrated What's more, the copper species distribution changed after hydrothermal aging over Cu 3.44 -SAPO-34 and Cu 5.15 -SAPO-34.…”

“…Reducing NOx emissions is important for the improvement of air quality. The selective catalytic reduction of NOx by NH 3 engines [1]. Due to the unstable operating conditions of diesel engines and periodically increasing the exhaust temperature to replicate diesel particulate filter (DPF) regeneration, excellent catalysts should meet the following essential requirements: good SCR activity over a wide operating temperature window, high selectivity for N 2 , and outstanding hydrothermal stability.…”

“…Copper-based zeolites have been suggested as efficient catalysts for the NH 3 -SCR reaction [2][3][4][5], and Cu-ZSM-5 was proposed to be the most promising [6,7]. However, the structure of the Cu-ZSM-5 catalyst collapsed easily after high temperature hydrothermal aging, leading to a conspicuous decline in NH 3 -SCR activity [8].…”

“…However, the structure of the Cu-ZSM-5 catalyst collapsed easily after high temperature hydrothermal aging, leading to a conspicuous decline in NH 3 -SCR activity [8]. Recently, Cu-CHA catalysts, (Cu supported on microporous zeolites ($0.38 nm pore size)), such as Cu-SSZ-13 and Cu-SAPO-34, have attracted much attention due to their higher NH 3 -SCR activity and better hydrothermal stability compared to large or mesopore Cu-based zeolite catalysts [9,10].…”

ROTACAT: A Rotating Device Containing a Designed Catalyst for Highly Selective Hydroformylation

“…Only very little of ligand A could be loaded on a SiC monolith of 3.5 g. To increase the surface area the SiC monoliths were first wash-coated with a porous silica top-layer of approximately 15 weight percent. [20,21] To this end monoliths were dipped in a colloidal silica solution in water. After the excess of liquid was removed the silica layer was casted at elevated temperature.…”