R. Nickolov

Oxidized carbon as a support of copper oxide catalysts for methanol decomposition to hydrogen and carbon monoxide

Abstract Copper oxide supported on oxidized activated carbon is investigated as a catalyst for methanol decomposition to H2 and CO. The influence of the medium of the precursor deposition on the state of the active phase is observed. The role of the chemical nature of the support in the formation of catalytic active complex is discussed.

Copper oxide supported on carbon modified alumina as catalyst for reduction of NO with CO.

Carbon-modified alumina-supported copper oxide catalysts have been investigated. The samples have been prepared by modified incipient techniques. The gamma-Al(2)O(3)-supported carbon phase permits sufficient modification of the chemical nature of the support surface in the region of low carbon contents without changing the specific surface area and the mesoporous character of the samples as compared to those of initial gamma-Al(2)O(3). In addition, the surface oxygen groups of the carbon phase, similar to the hydroxyl groups of the alumina surface, affect the formation and type of copper oxide phase. It has been established that the catalysts investigated have high activity in the reduction of NO with CO, the highest activity belonging to the Cu17AC/AL catalyst, which contains the largest amount of carbon. This sample is also active with respect to the direct decomposition of NO.

NOVEL APPLICATION OF DEPLETED FULLERENE SOOT (DFS) AS SUPPORT OF CATALYSTS FOR LOW-TEMPERATURE REDUCTION OF NO WITH CO

Depleted fullerene soot (DFS) with fullerene residue content of about 2.2-3.2% are investigated in order to elucidate the possibility for their use as support of catalysts in low-temperature reduction of NO with CO. Bimetalic copper-cobalt and copper-manganese oxides supported on DFS are prepared. All samples are characterized by chemical analysis, XRD, SEM, IR spectroscopy, XPS, nitrogen adsorption measurements. The two DFS supported bimetallic catalysts manifest a high activity towards the reduction of NO with CO at temperatures below 150 degrees C, the CuCo/DFS being the more active one. The peculiarity of the support DFS predetermines the porous texture of the catalysts. The occurrence of a specific metal-support interaction favors the formation of the mixed oxide spinels CuCo2O4 and Cu1.5 Mn1.5 O4 that are responsible for the enhanced activity.

Effect of Chromium on Copper Containing Activated Carbon Catalysts for Methanol Decomposition

The decomposition of methanol was studied on Cu or Cu-Cr catalysts supportedon activated carbon, prepared by active phases decomposition from theirammonium solutions. Catalytic active centers with a complex character,consisting of copper ions in different oxidation state, were found to be present.They determine the high activity and selectivity of the catalysts.

Determination of nitrogen structures on activated carbon surfaces by a chemical method

Abstract A method is proposed for determination of surface compounds containing nitrogen incorporated into activated carbon and other carbon adsorbents. The method is based on the redox reaction between hydrochloric acid and the surface compounds. Materials obtained by treating activated carbon with concentrated nitric acid or hydrogen peroxide as well as by passing nitric oxide through the carbon and by thermal treatment of samples pretreated with nitric acid were investigated. It was established that the redox reaction on which the method is based proceeds only in the presence of surface groups containing both nitrogen and oxygen. I.r. spectroscopy and XPS showed that organic nitrates and nitrate complexes containing NO 3 − can be determined by the method.

Ftir spectroscopic study of NH3 and no adsorption on alumina-supported manganese oxide catalyst

Adsorption and coadsorption of NH3 and NO on alumina-supported manganese oxide catalyst prepared from manganese formate precursor has been studied by means of FTIR spectroscopy.

Porous Texture of CuO Prepared from Copper Oxalate Precursor

The porous texture of CuO obtained from CuC2O4 • 0.5H2O as a precursor, as well as the interconnection between the texture of the initial oxalate and that of the copper oxide obtained, has been studied by physisorption, XRD, XPS and SEM methods. The dimensions of the particle aggregates and the crystalline particles were altered as a consequence of the thermal decomposition of CuC2O4 • 0.5H2O to CuO, and this led to an increase of ca. 1.5-times in the specific surface of the CuO obtained relative to that of the initial substance. The comparatively non-uniform sizes of the intra-aggregate mesopores in CuC2O4 • 0.5H2O were transformed into considerably smaller intra-aggregate mesopores in CuO. A finite increase in the volume of the intra-crystallite pores in CuO was also observed, although this did not change the average size of the intra-crystallite pores in the oxide obtained nor the character of the pore-size distribution with respect to the starting material. In addition, as a result of the thermal decomposition of CuC2O4 • 0.5H2O, the mesoporosity of the prepared oxide also developed. However, the CuO component retained the textural type characteristic of the initial CuC2O4 • 0.5H2O.

FTIR spectroscopy of NH3 and NO adsorption on copper-on-alumina catalysts

Adsorption and coadsorption of NH3 and NO on copper-on-alumina catalysts prepared from formate precursors by calcination at 670 and 870 K was studied by means of FTIR spectroscopy. It has been established that the sample prepared at lower temperature exhibits a higher activity with respect to NO reduction with ammonia.

Promoting effect of Zn2+ on active carbon-supported Cu oxide catalysts for no reduction

The effect of Zn2+ on the active copper phase and on the active carbon support of catalysts for nitrogen oxide reduction has been investigated.