Denitration Catalyst Research Articles

Microwave Catalytic Conversion of SO 2 and NO x over Cu/zeolite

Abstract: Microwave catalytic technology is a promising technology for flue gas treatment. Cu/zeolite was used as catalyst for microwave catalytic desulfurization and denitrification and for microwave catalytic reduction of SO 2 and NOx with ammonium bicarbonate (NH 4 HCO 3 ) as a reducing agent. Microwave catalytic desulfurization and denitrification efficiency achieved 76.1 and 81.8% separately. The reaction efficiency of microwave catalytic reduction of SO 2 and NO x could be up to 99.8 and 92.8% respectively. The physico-chemical properties of Cu/zeolite catalysts were characterized by X-ray diffraction analysis (XRD), Brunauer-Emmett-Teller measurements (BET), X-ray photoelectron spectrum analysis (XPS), scanning electron microscopy (SEM).The XPS results indicate that sulfide (SO4 2- ), element sulfur (S 0 ) and NH 4 + species exist on the catalyst surface after the reaction. Microwave catalytic SO 2 and NO x removal follows Langmuir — Hinshelwood(L-H) kinetics. Key words: Simultaneous desulfurization & denitrification; Microwave catalytic technology; Cu/zeolite; Characterization

Simultaneous Desulfurization and Denitrification by Microwave Catalytic over FeCoCu/Zeolite 5A Catalyst

FeCoCu/zeolite 5A was used as a catalyst for microwave catalytic desulfurization and denitrification and for microwave catalytic reduction of SO2 and NOx with ammonium bicarbonate ( NH4 HCO3 ) as a reducing agent. Microwave catalytic desulfurization and denitrification efficiency attained 99.5 and 86.1%, respectively. The reaction efficiencies of microwave catalytic reduction of SO2 and NOx could be up to 95.8 and 95.1% separately; the optimal microwave power and empty bed residence time on microwave catalytic reduction of SO2 and NOx simultaneously are 280 W and 0.358 s, respectively. Microwave accentuates catalytic reduction treatment, and microwave addition can increase the SO2 and NOx removal efficiency. The microwave catalytic SO2 and NOx removal follows the Langmuir-Hinshelwood model.

Novel Pd-Cu/bacterial cellulose nanofibers: Preparation and excellent performance in catalytic denitrification

In this work, we describe a novel facile method to prepare long one-dimensional hybrid nanofibers by using hydrated bacterial cellulose nanofibers (BCF) as template. Palladium-copper nanoparticles were prepared in BCF by immersing BCF in a mixture solution of PdCl 2 and CuCl 2 in water and followed reduction of absorbed metallic ion inside of BCF to the metallic Pd-Cu nanoparticles using potassium borohydride. The bare BCF and the composites were characterized by a range of analytical techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results reveal that the Pd-Cu nanoparticles were homogeneously precipitated on the BCF surface. The Pd-Cu/BCF was used as a catalyst for water denitrification, which showed that it has high catalytic activity.

NO 2− adsorption onto denitration catalysts

The performance of denitration catalysts is usually evaluated according to the concentrations of NO 3 −, NO 2 − and NH 4 + ions. Catalytic conversion is conventionally calculated from the decrease of NO 3 − and NO 2 − in the reaction solution. In this study, batch experiments were performed by contacting NO 2 − with Pt/Al 2O 3 under the presence or absence of H 2 flow. Significant amounts of NO 2 − in the reaction solution disappeared even in the absence of H 2, i.e., under conditions where reduction did not occur. This phenomenon is explained by NO 2 − adsorption onto Al 2O 3. The equilibrium amount of adsorbed NO 2 − showed a linear decrease with the increase of Pt particles. The adsorption of NO 2 − onto Al 2O 3 should be considered when the performance of denitration catalysts is evaluated. In addition, utilizing the high adsorption capacity of Al 2O 3 for NO 2 − may realize its potential as a scavenger for the removal of NO 2 − ions in waste water.

Bi modified Pd/SnO2 catalysts for water denitration

A Pd/SnO2 catalyst was doped with low concentrations of Bi in order to induce selective poisoning of sites on the Pd surface in order to test a hypothesis that specific surface sites are responsible for ammonium formation during the catalytic hydrogenation of nitrates from drinking water. Initial addition of low levels of Bi appeared to selectively titrate high-energy surface Pd atoms located in the high index planes of the Pd crystallites. Addition of Bi had little effect on catalyst activity but modified selectivity profiles of nitrite and ammonium formation.

Characterization by Mössbauer spectroscopy of trimetallic Pd–Sn–Au/Al2O3 and Pd–Sn–Au/SiO2 catalysts for denitration of drinking water

The reduction of nitrate using a catalytic process is one of the most interesting ways to solve the problem of drinking water pollution by this compound. The key parameter of this technique is the selectivity toward nitrogen formation. Palladium/tin-based bimetallic catalysts are well suited for this purpose, but the selectivity of these catalysts is not high enough for a direct application of this process. In the present study, alumina- and silica-supported catalysts were prepared by successive deposition of tin and gold onto palladium particles by using controlled surface reaction. The characterization of trimetallic Pd–Sn–Au catalyst evidenced that trimetallic catalysts supported on silica present a palladium/tin/gold phase. The catalytic test showed that this type of catalyst is very active and selective in nitrate and nitrite reduction. Moreover, the addition of gold improves the stability and the selectivity toward nitrogen formation of the catalyst compared to the parent Pd–Sn catalyst.

等方超高圧成形により粒子間マクロ細孔を除去したメソポーラスシリカ成形体の脱硝触媒特性

等方超高圧成形により粒子間マクロ細孔を除去したメソポーラスシリカ成形体の脱硝触媒特性

Denitration catalysts for diesel exhaust gases

Denitration catalysts for diesel exhaust gases

高温脱硫剤型脱窒触媒の開発

高温脱硫剤型脱窒触媒の開発