Zeolite-supported Cobalt Research Articles

Zeolite-supported cobalt catalysts derived from natural diatomite with high catalytic activity for catalyzing NaBH4 hydrolysis

Zeolite-supported cobalt catalysts derived from natural diatomite with high catalytic activity for catalyzing NaBH4 hydrolysis

Fabrication of zeolite-supported cobalt ferrite (CoFe2O4/ H-zsm-5) catalyst for the synthesis of 4-(9-(4-substituted)-1,2,3,4,5,6,7,8-octahydro-3,3,6,6-tetramethyl-1,8-dioxoacridin-10(9H)-yl)benzoic acid derivatives in semi aqueous condition

A cobalt ferrite (CoFe2O4/H-ZSM-5) catalyst supported by zeolite has been studied as a multicomponent reaction for making dioxoacridin-10(9H)-ylbenzoic acid derivatives in semi-aqueous conditions. This reaction offers a cost-effective and simple operational strategy and provides different substrates. Scope and various functional groups are well tolerated under optimized reaction conditions. Firstly, the catalyst was characterized using FT-IR, XRD, BET, XPS, TGA, and SEM techniques. The study determined the optimal operating conditions for achieving an efficient synthesis of target organic compounds. The optimized conditions for the synthesis of model compounds (4a) with a yield of 96 % were achieved through a reaction time of 40 min, a catalyst amount of 10 mol%, a temperature of 90 °C, and a solvent of 6/4 of the ethanol and water mixture. All of the characterization measurements confirmed that the catalyst's stability remained unaltered even after four consecutive cycles of the synthesis of model compounds. Furthermore, the reusability feature cuts costs and lessens environmental effects, making it an appealing option for practical applications. The findings emphasize this approach's enormous potential for sustainable chemical synthesis, opening the path for future advances in the sector. In addition, an experiment was set up to look into the thermodynamic and kinetic properties of compound (4a) when it was heated to between 343.15 and 373.15 K with the help of a catalyst. The current investigation has shown that the reaction favors thermodynamics rather than kinetic control.

Selective catalytic reduction of NO with CH4 over cobalt-exchanged cage-based, small-pore zeolites with different framework structures

Selective catalytic reduction of NO with CH4 (CH4-SCR) has been studied over divalent cobalt ions exchanged into four cage-based, small-pore zeolites with different framework topologies, i.e., Co-CHA, Co-RTH, Co-UFI, and Co-LTA with similar Si/Al and Co/Al ratios (10–11 and 0.44 – 0.49, respectively). The catalytic results obtained are compared with those of Co-ferrierite, one of the most active catalysts for this reaction. While the CH4-SCR activity of all zeolite-supported cobalt catalysts decreases under wet conditions, the activity of Co−CHA is least affected by water vapor, thereby outperforming Co-ferrierite. More interestingly, a decrease in Si/Al ratio of its support from 10 to 6 gave a NO conversion to N2 of 90 % at 773 K under wet conditions. The overall characterization results of this study demonstrate that both the framework topology and composition of zeolite supports are critical factors determining the intrazeolitic Co2+ ion locations and thus their CH4-SCR activity.

Trace mono-atomically dispersed rhodium on zeolite-supported cobalt catalyst for the efficient methane oxidation

The partial oxidation of methane is a promising method for the efficient production of syngas. To implement this process using common stainless steel reactors, an inexpensive catalyst that functions at 650 °C or below is necessary. However, base metal catalysts typically require much higher temperatures, and they are deactivated by re-oxidation and coke formation. Here we report that modification of a zeolite-supported 3 wt% cobalt catalyst with a trace amount of mono-atomically dispersed rhodium (0.005 wt%) dramatically improves catalytic performance and durability. Cobalt/mordenite is nearly inactive due to the oxidation of cobalt, but the catalyst modified with rhodium continuously gives 85–86% methane conversion and 90–91% CO selectivity with an H2/CO ratio of 2.0 without serious coking at 650 °C. During the reaction, mono-atomically dispersed rhodium converts cobalt oxide to Co0 active species via hydrogen spillover. Use of the zeolite support is key to the high catalytic performance.

Direct 2-Alkylation of Azoles with Ethers on Zeolite-Supported Cobalt

Key words cobalt catalysis - C–H functional-ization - azoles - ethers

Removal of Phenol Using Sulphate Radicals Activated by Natural Zeolite-Supported Cobalt Catalysts

Two Co oxide catalysts supported on natural zeolites from Indonesia (INZ) and Australia (ANZ) were prepared and used to activate peroxymonosulphate for degradation of aqueous phenol. The two catalysts were characterized by several techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS) and N2 adsorption. It was found that Co/INZ and Co/ANZ are effective in activation of peroxymonosulphate to produce sulphate radicals for phenol degradation. Co/INZ and Co/ANZ could remove phenol up to 100 and 70 %, respectively, at the conditions of 25 ppm phenol (500 mL), 0.2 g catalyst, 1 g oxone and 25 °C. Several parameters such as amount of catalyst loading, phenol concentration, oxidant concentration and temperature were found to be the key factors influencing phenol degradation. A pseudo first order would fit to phenol degradation kinetics, and the activation energies on Co/INZ and Co/ANZ were obtained as 52.4 and 61.3 kJ/mol, respectively.

Effect of the Mesostructuration of the Beta Zeolite Support on the Properties of Cobalt Catalysts for Fischer–Tropsch Synthesis

The effect of mesostructuration of beta zeolite and of metal loading on the properties of cobalt-based catalysts for Fischer–Tropsch synthesis was studied in this work. The most active catalyst was the mesostructured beta zeolite-supported cobalt (10%), which also showed a low selectivity to methane and the lowest olefin/paraffin ratio.

Characterization of highly dispersed cobalt sulfide catalysts by X-ray absorption fine structure and magnetic properties

Zeolite-supported cobalt sulfide catalysts, CoS/NaY and CoS/USY-H, were prepared using Co(CO) 3NO as a precursor. A SiO 2-supported cobalt sulfide catalyst was prepared by an impregnation method for comparison. The prepared catalysts were characterized by magnetic properties and XAFS. The cobalt sulfides in CoS/NaY are paramagnetic and can be characterized as intrazeolite dinuclear species with antiferromagnetic interactions between the Co atoms, in contrast to the cobalt sulfides in CoS/SiO 2, in which 95% of Co is Co 9S 8 and 5% is paramagnetic with a very small amount of ferromagnetic species. The structure of the cobalt sulfides in CoS/USY-H depends on the treatment after the sulfidation. Ultra-highly dispersed cobalt sulfide species initially formed during the sulfidation are transformed to highly dispersed Co 9S 8-like particles and eventually to ion-exchanged Co 2+ cations as the evacuation temperature and duration are increased. The catalytic activity of the cobalt sulfide catalysts was measured for the hydrodesulfurization of thiophene. The results suggest a synergy generation between cobalt sulfides and surface hydroxyl groups.

Zeolite-supported cobalt catalysts for the conversion of synthesis gas to hydrocarbon products

Three differently prepared cobalt/ZSM-5 catalysts were investigated with respect to physical and chemical properties and to activity and selectivity for conversion of synthesis gas. The catalyst preparations consisted of the following: (1) direct decomposition of C/sub 5/H/sub 5/Co(CO)/sub 2/ on ZSM-5, (2) impregnation of ZSM-5 with an aqueous solution of cobalt nitrate, and (3) physical admixture of precipitated cobalt oxide with ZSM-5. At about 3 wt % cobalt loading, the first catalyst showed higher dispersion, higher (H/sub 2/ + CO) conversion, and about 10 times higher yield of gasoline-range hydrocarbons (g/h) than the catalyst prepared by the other two methods. Some H/sub 2/ and CO chemisorption studies and magnetization measurements were conducted to measure the average particle diameter. Infrared studies of chemisorbed pyridine of these samples indicate that ion exchange of Co/sup 2 +/ for acidic protons occurs in organometallic-impregnated and aqueous solution-impregnated catalysts. 18 references, 6 figures, 4 tables.