High-Performance Mn-Al-O Catalyst on Reticulated Foam Materials for Environmentally Friendly Catalytic Combustion

MnOx supported on alumina and La2O3-modified alumina have been prepared and characterized as methane combustion catalysts. X-ray diffraction (XRD) analysis has revealed the significant low-temperature interaction between MnOx and alumina, resulting in a solid solution Mn-La-γ*-Al2O3 and a hexaaluminate formation upon thermal treatment at 900-1000 ºC and 1300 ºC, respectively. Mn-Al-O and Mn-La-Al-O catalysts washcoated on highly porous reticulated foam materials (RFM) have been prepared by two methods, such as: 1) a wet impregnation of a washcoating alumina layer on RFM by Mn and La nitrate solutions, 2) a dip coating of RFM into Mn-La-Al-containing suspension. The chemical compositions of RFM were cordierite, Ni, and NiCr-alloy. The catalytic activity of washcoated RFM in the methane combustion has been compared with one of granulated catalysts. The influence of alumina form (γ-Al2O3, (γ+χ)-Al2O3, α-Al2O3), manganese loading (5 and 10 wt.%), modifying agent (La2O3) on catalytic activity have been studied. Catalytic performances of Mn-Al-O and Mn-La-Al-O catalysts washcoated on RFM and pretreated in methane-containing atmosphere at 1100 ºC have been investigated. The Mn-Al-O catalyst modified by La2O3 and supported on RFM have been tested in a prototype catalytic water heating boiler and demonstrated a considerable reduction in the emissions of NOx and CO compared to the conventional household boilers. The washcoating of the Mn-La-Al-O catalyst over surface of RFM provides a substantial reduction of toxic  emissions during the catalytic fuel combustion. While an optimal foam structure and composition of the RFM provide improved heat and mass transfer properties of the catalyst in fuel combustion

Direct Catalytic Reduction of SO2 by CH4 over Fe-Mn Catalysts Prepared by Granulation of Ferromanganese Nodules

The chemical, textural, structural and strength properties of ferromanganese nodules and granulated Fe-Mn catalysts containing such nodules were studied. It was found that the granulated catalysts have a developed pore structure, which is close to that of the starting material, and surpass the starting material in strength parameters. The catalysts were tested in desulfurization by methane at a stoichiometric ratio SO2/CH4 = 2. The testing showed that Fe-Mn catalysts with the oxide or sulfide form of active components are active in desulfurization by methane and can selectively reduce SO2 with a conversion above 80%

New Gas-Phase Catalytic Oxidative Processes for Desulfurization of Diesel Fuel

An effective gas-phase oxidative desulfurization (ODS) process was proposed. The process was studied in a laboratory reactor with a proprietary catalyst at 300-400 ºС and ambient pressure with model fuels represented by thiophene, dibenzothiophene(DBT) and 4,6-dimethyldibenzothiophene (DMDBT) dissolved in octane, isooctane or toluene. The reactivity of different sulfur containing molecules in ODS was shown to increase in the sequence: thiophene<DBT<DMDBT. The main sulfur containing product of oxidation of these compounds was SO2. During the gas-phase ODS both processes of sulfur species oxidation and processes of their adsorption were observed and studied. Based on the conducted studies, different ODS process designs comprising its integration with adsorption and regeneration processes and with conventional hydrodesulfurization (HDS) process were proposed. One scheme is based on alternating regimes of ODS and catalyst regeneration in two reactors: sulfur is removed from organic feedstock by oxidation and adsorption in one reactor while simultaneous regeneration of the catalyst that has accumulated sulfur compounds takes place in another reactor. Two other schemes are based on joint use of ODS and HDS. The conventional HDS process is most effective for removal of low-boiling sulfur containing compounds reactive with respect to hydrogen, while removal of refractory sulfur compounds, such as DMDBT is more easily achieved by gas phase ODS. Thus the combination of these processes is expected to be most efficient for deep desulfurization of diesel fuel

Catalytic Synthesis of Thiophene from Dialkyl Disulfides and n -Butane

A modern industrial process for hydrocarbon feedstock cleaning of mercaptans is their oxidation to dialkyl disulfides with molecular oxygen in an alkaline medium in the presence of phthalocyanine catalysts [1 − 4]. The following main reactions relevant to this treatment for the removal of mercaptans occur in the material: 2 RSNa + 0.5 O 2 + H 2 O RSSR + 2 NaOH . As follows from this scheme, a byproduct of the process is a mixture of organic dialkyl disulfides RSSR, the so-called disulfide oil (DSO), a waste whose disposal from demercaptanization units is still an unresolved problem. To date, the disulfide oil has not found qualified application and is practically undisposable; meanwhile, its storage creates a safety hazard. Thus, the stock of DSO produced all over the world continuously grows. Therefore, the problem of the utilization of the disulfide oil via its processing into chemicals that are in demand is of great importance. One of the possible ways of coping with the problem is the conversion of DSO into thiophene, a compound used for the synthesis of a range of valuable drugs for human and veterinary medicine, as well as chemicals for agriculture (herbicides and pesticides) At present, according to In this work, we studied the feasibility of thiophene synthesis from organic dialkyl disulfides (disulfide oil) and n -butane using a modified magnesia-chromia-alumina catalyst. EXPERIMENTAL Feedstock components used in laboratory studies of thiophene synthesis were dimethyl disulfide containing a 99.57 wt % base substance; a mixture of organic dialkyl disulfides (disulfide oil) from the propanebutane demercaptanization unit (Orenburg gas processing plant) with dimethyl disulfide, methyl ethyl disulfide, and diethyl disulfide contents of 69.69, 24.54, and 3.15 wt %, respectively; and a grade B n -butane cut (TU (Technical Specifications) 0272-026-00151638-99) which contained 88.0 wt % n -butane (OAO Nizhnekamskneftekhim). A special catalytic system containing chromium and magnesium oxides as an active component and potassium and/or lanthanum oxides as a promoter of the general formula , where t lies in the range 5 wt %; x , y , and z are at most 3.2, 2, and 10 wt %, respectively; and the value of n ranges within 0-1, was designed for the thiophene Abstract -A promising new method for thiophene synthesis on the basis of dialkyl disulfides (byproduct of demercaptanization of hydrocarbon feedstocks) catalyzed by a modified magnesia-chromia-alumina catalyst was developed

Atomic Structure of Pd-, Pt-, and PdPt-Based Catalysts of Total Oxidation of Methane: In Situ EXAFS Study

In this study, 3%Pd/Al2O3, 3%Pt/Al2O3 and bimetallic (1%Pd + 2%Pt)/Al2O3 catalysts were examined in the total oxidation of methane in a temperature range of 150&ndash;400 &deg;C. The evolution of the active component under the reaction conditions was studied by transmission electron microscopy and in situ extended X-ray absorption fine structure (EXAFS) spectroscopy. It was found that the platinum and bimetallic palladium-platinum catalysts are more stable against sintering than the palladium catalysts. For all the catalysts, the active component forms a &ldquo;core-shell&rdquo; structure in which the metallic core is covered by an oxide shell. The &ldquo;core-shell&rdquo; structure for the platinum and bimetallic palladium-platinum catalysts is stable in the temperature range of 150&ndash;400 &deg;C. However, in the case of the palladium catalysts the metallic core undergoes the reversible oxidation at temperatures above 300 &deg;C and reduced to the metallic state with the decrease in the reaction temperature. The scheme of the active component evolution during the oxidation of methane is proposed and discussed

Application of POSS nanotechnology for preparation of efficient Ni catalysts for hydrogen production

\u3cp\u3ePOSS (polyhedral oligomeric silsesquioxanes) nanotechnology was applied for preparation of efficient Ni catalysts for hydrogen production through autothermal reforming of methane (ATR of CH\u3csub\u3e4\u3c/sub\u3e). The novel metal-POSS precursor [Nickel (II) ‒ HeptaisobutylPOSS (C\u3csub\u3e4\u3c/sub\u3eH\u3csub\u3e9\u3c/sub\u3e)\u3csub\u3e7\u3c/sub\u3eSi\u3csub\u3e7\u3c/sub\u3eO\u3csub\u3e9\u3c/sub\u3e(OH)O\u3csub\u3e2\u3c/sub\u3eNi] of Ni nanoparticles was introduced into Ce\u3csub\u3e0.5\u3c/sub\u3eZr\u3csub\u3e0.5\u3c/sub\u3eO\u3csub\u3e2\u3c/sub\u3e support with following calcination and reduction stages of activation. The peculiarity of the genesis of Ni/SiO\u3csub\u3e2\u3c/sub\u3e/Ce\u3csub\u3e0.5\u3c/sub\u3eZr\u3csub\u3e0.5\u3c/sub\u3eO\u3csub\u3e2\u3c/sub\u3e nanomaterials and their characteristics versus deposition mode were studied by X-ray fluorescence spectroscopy, thermal analysis, N\u3csub\u3e2\u3c/sub\u3e adsorption, X-ray diffraction, high-resolution transmission electron microscopy and H2 temperature-programmed reduction. The two kinds of supported Ni-containing particles were observed: highly dispersed Ni forms (1‒2 nm) and large Ni-containing particles (up to 50‒100 nm in size). It was demonstrated that the textural, structural, red-ox and, consequently, catalytic properties of ex-Ni-POSS catalysts depend on the deposition mode. The increase of a portion of difficultly reduced Ni\u3csup\u3e2+\u3c/sup\u3e species is found upon application of intermediate calcination during Ni-POSS deposition that has detrimental effect on the activity of catalyst in ATR of CH4. The Ni/SiO\u3csub\u3e2\u3c/sub\u3e/Ce\u3csub\u3e0.5\u3c/sub\u3eZr\u3csub\u3e0.5\u3c/sub\u3eO\u3csub\u3e2\u3c/sub\u3e catalyst prepared by one-step Ni-POSS deposition exhibits the highest H\u3csub\u3e2\u3c/sub\u3e yield ‒ 80% at T = 800 °C.\u3c/p\u3

Application of POSS nanotechnology for preparation of efficient Ni catalysts for hydrogen production

POSS (polyhedral oligomeric silsesquioxanes) nanotechnology was applied for preparation of efficient Ni catalysts for hydrogen production through autothermal reforming of methane (ATR of CH4). The novel metal-POSS precursor [Nickel (II) ‒ HeptaisobutylPOSS (C4H9)7Si7O9(OH)O2Ni] of Ni nanoparticles was introduced into Ce0.5Zr0.5O2 support with following calcination and reduction stages of activation. The peculiarity of the genesis of Ni/SiO2/Ce0.5Zr0.5O2 nanomaterials and their characteristics versus deposition mode were studied by X-ray fluorescence spectroscopy, thermal analysis, N2 adsorption, X-ray diffraction, high-resolution transmission electron microscopy and H2 temperature-programmed reduction. The two kinds of supported Ni-containing particles were observed: highly dispersed Ni forms (1‒2 nm) and large Ni-containing particles (up to 50‒100 nm in size). It was demonstrated that the textural, structural, red-ox and, consequently, catalytic properties of ex-Ni-POSS catalysts depend on the deposition mode. The increase of a portion of difficultly reduced Ni2+ species is found upon application of intermediate calcination during Ni-POSS deposition that has detrimental effect on the activity of catalyst in ATR of CH4. The Ni/SiO2/Ce0.5Zr0.5O2 catalyst prepared by one-step Ni-POSS deposition exhibits the highest H2 yield ‒ 80% at T = 800 °C