Contemporaneous Removal of SO₂ and NO from Flue Gas Using a Regenerable Copper-on-Alumina Sorbent—Catalyst

Abstract

The kinetics and reaction mechanism of SO 2 oxidation-sorption (DeSOx) and simultaneous reduction of NO by NH 3 /O 2 (DeNOx) on copper oxide on alumina are presented with reference to the development of this system for the application to a dry technology for the removal of SO 2 and NO from flue gas based on a regenerable sorbent-catalyst. The DeSOx reaction kinetics and differences for fresh and for stabilized samples and the influence of pellet diameter and support porosity characteristics on the efficiency of SO 2 capture are reported. Aspects of the nature of the active copper sites and differences between fresh and stabilized samples, regenerability of sulphated samples and behavior of copper-on-alumina in the conversion of NO to N 2 by NH 3 /O 2 during the simultaneous capture of SO 2 are also discussed.The worldwide trend toward lower levels of pollutant emissions from power generating plants has spurred significant interest in the development of new less costly technologies capable of reducing emissions of SO2 (DeSOx) and NOx (DeNOx). State-of-the-art power plants employ individual unit operations for SO2 and NOx control. Wet or dry flue gas desulphurization (FGD) systems can achieve 70 to 90% SO2 removal, depending on process design, fuel characteristics and emission regulations, and selective catalytic reduction (SCR) systems are also achieving more than 80% NO reduction. A process design integrating SO2 and NOx removal in a single unit operation offers the potential for reducing the cost of environmental control; such a design, however, should adhere to the following requirements:• minimum waste production or the formation of valuable by-products• rnirtimization of energy use, especially in the cooling or reheating of flue gas, i.e. the technology must operate at the same temperature as that of the flue gas after the first economizer (around 350°C)

Reductive Regeneration of Sulfated CuO/Al2O3 Catalyst−Sorbents in Hydrogen, Methane, and Steam

“…, from the reduction of copper sulfide (Cu 2 S or CuS) or aluminum sulfate species (McCrea et al, 1970;Centi et al, 1990Centi et al, , 1994.…”

“…The formation of Cu 2 S was predicted by Dautzenberg et al (1971), Princiotta et al (1979), and more recently by Kiel et al (1992) while McCrea et al (1970) and Centi et al (1990) proposed that CuS forms during reduction of the sulfated catalyst-sorbent with H 2 . In addition, H 2 S formation is also a possibility at temperatures above 500 °C, from the reduction of copper sulfide (Cu 2 S or CuS) or aluminum sulfate species (McCrea et al, 1970;Centi et al, 1990Centi et al, , 1994.…”

Ammonia Adsorption and Oxidation on Cu/Mg/Al Mixed Oxide Catalysts Prepared via Hydrotalcite-Type Precursors

“…CuO−Al 2 O 3 powders have also been proposed as regenerable adsorbant catalysts for the DeSO x −DeNO x processes where SO 2 and SO 3 are adsorbed in the form of sulfates and NO x are simultaneously reduced by ammonia. , …”

Selective Catalytic Reduction of NO by Ammonia over Raney-Ni Supported Cu-ZSM-5 I. Catalyst Activity and Stability

“…Some more hours in a feed containing both H 2 O and SO 2 result in some loss of high-temperature activity in dry feed as compared to the fresh catalyst (Panel B), but the deactivation in the lowtemperature region is much more dramatic. These results arise most likely from the different roles that copper oxide clusters and particles play in the SCR with hydrocarbons or ammonia: With hydrocarbons, CuO is completely unselective [18,19] while oxide clusters, as in CuO/Al 2 O 3 , are known to catalyse the SCR with ammonia even while being converted into sulphate by SO 2 from the feed [20,21]. The effect of the durability experiment on the SCR activity under dry conditions is quite different with the intergrown composite (Fig.…”