Study on SO₂-Absorption Behavior of Composite Materials for DeSO_xFilter From Diesel Exhaust

Abstract

4DENOSO Corporation, Kariya city, Aichi Prefecture, Japan NO x emitted from diesel engines is one of the major air pollutants in most countries. To reduce NO x emission, NO x storage/reduction (NSR) catalysts have been developed for diesel systems. The catalyst for NSR is strongly poisoned with sulfur. This paper reports the synthesis of Na-doped CaCO 3 as a new material for SO 2 adsorption. Measurements of the desulfurization breakthrough characteristics using monolith washcoated Na-doped CaCO 3 were investigated at 450 • C. The Na-doped CaCO 3 absorbed ∼77.6-90.6 mg -SO 2 /g -material of SO 2 at 450 • C (where CaCO 3 is 8 mg -SO 2 /g -material ). Investigation of the source of the improved sulfur absorption capacity of the Na-doped CaCO 3 relative to the parent material via x-ray diffraction (XRD) and scanning electron microscopy-energy-dispersive x-ray spectroscopy (SEM-EDX) analyses revealed that the new material forms a composite partially composed of Na 2 Ca(CO 3 ) 2 . The enhanced SO 2 absorption capacity derived from the formation of composite materials is demonstrated herein. SO 2 contained in the exhaust gas is absorbed at a lower temperature than with previously reported systems. In order to elucidate the SO 2 absorption mechanism of the composite materials, further studies and synthesis of materials with greater absorption capacity are required.

Enhanced SO2 Capture Performance of MnO2 by Doping with Alkali Metal Ions for Diesel Emission Control

“…The low-temperature sulfate activation of the alkali metals doped MnO 2 depends on the oxidation of SO 2 [11]. The sulfate reactivity of the oxygen species was investigated by means of H 2 -TPR analysis.…”

“…It is found that the formed K 2 SO 4 was quite stable in the range between 180 °C and 550 °C. Osaka et al described the synthesis of Na‐doped CaCO 3 as a new material for SO 2 adsorption, and the sulfur absorption capacity of Na‐doped CaCO 3 was improved compared with fresh CaCO 3 . These studies discussed only the effects of SO x sorption of the potassium or sodium‐based sorbents; however, the SO 2 removal performance of lithium‐based MnO 2 sorbents is not mentioned.…”

Density functional theory studies on ortho-position adsorption of SO3 at step sites of a CaO surface with SO2 and CO2

“…It is well known that alkali metal oxides and alkaline-earth metal oxides present in coal fly ash partially capture acidic gaseous sulfur oxides, which are present in the flue gas [7,13,14]. However, to achieve sufficient solidification, alkaline sorbents are additionally being sprayed into the furnace or into the flue gas, such as CaO, MgO, Na 2 CO 3 , Ca (OH) 2 and Mg(OH) 2 [15][16][17][18][19][20][21]. Among the sorbents mentioned above, calcium-based sorbents are the most commonly used because they are affordable, easy to obtain and can remove SO 3 with a high efficiency (above 80%) [17,21].…”

Development of SO₂ Absorption Materials Having Low Temperature Activity by Base Adducted Complex Method

“…In this study, the amorphous citric acid complex method is focused on as a physically modification of CaCO 3 [4]. Then, base adducted complex method is focused on the chemically modification of CaCO 3 [5]. CaCO 3 having more low temperature activation is proposed by combining both method.…”