Catalyst impregnated activated carbons

Benzene hydroxylation to Phenol with Iron impregnated Activated carbon Catalysts... 

To study the effect of solvents, reactions carried out with acetonitrile ( benzene acetonitrile = 1 4.65, 1 6.58 mole ratio), and acetone (benzene acetone = 1 6.58 mole ratio) as solvents on 5.0 wt% iron impregnated activated carbon catalyst and the results were compared. The results are... 

The preparation of iron impregnated activated carbon as catalysts and the catalytic performance of these catalysts were studied in benzene hydroxylation with hydrogen peroxide as oxidant. 5.0Fe/AC catalyst containing 5.0 wt% iron on activated carbon yielded about 16% phenol. The addition of Sn on 5.0Fe/AC catalyst led to the enhancement of selectivity towards phenol. 

Catalysts from active carbon promoted with mixed Ni-Co- oxides are investigated [8], These catalysts are produced by heat-treatment of active carbon impregnated with solution containing Co-and Ni-acetates. The concentration of the used Co and Ni- solutions is varied in order to optimise the content of the mixed Co-Ni oxides in the catalyst. 

Activated carbon when used can work as a reducing agent, as a catalyst, and as an adsorbent. When used as a catalyst, the activated carbons are impregnated with metals that can reduce the temperature required for the reduction of the oxides of nitrogen to nitrogen. The reduction in temperature could be 600 to 700°C for an imcatalyzed reaction to as low as 300°C for a catalyzed reaction. Copper is one of the metals which, when impregnated on the surface of carbon, can significantly... 

In industrial applications activated carbons are used as supports for precious metal and metal oxide catalysts. These catalysts can be prepared by adsorption from solution, impregnation, precipitation and other techniques as gas phase deposition [4]. The most common way of preparation is adsorption and impregnation by bringing the activated carbon in contact with a solution of the desired metal compound or with a solution of a metal precursor, in most times a complex salt. Then the impregnated activated carbon is dried. Reduction is carried out when the metal precursor has to be transformed in the metal. Important quality criteria are ... 

RuCls 3H2O is the most common ruthenium compound containing chlorine with stable properties. It easily dissolves in water and is cheaper than other ruthenium compounds. In the past, the ruthenium catalysts were prepared by impregnation with RuCIs as the precursor and water as solvent. However, the chlorine of remnant after reduction can poison the ruthenium catalysts when a metal oxide is adopted as a support. The poison effect of chlorine is not so obvious for ruthenimn catalysts with activated carbon as support. ... 

Molecular sieves have also found application for desulfurization of natural-gas feed to ammonia plants. Removal of all types of sulfur compounds ahead of these plants is desirable because sulfur acts as a temporary poi.son to steam-hydrocarbon reforming catalysts and a permanent poison to expensive low-temperature shift conversion catalysts. An installation employing a standard dual bed adsorption system has been described by Lee and Collins (1968). The authors also describe comparative tests of a molecular sieve and a commercial grade of impregnated activated carbon in a dual-bed mobile pilot unit. The test results indicated that the molecular sieve could treat 2 to 4 times as much gas per unit volume of adsorbent as the carbon. The commercial plant consistently provided gas to the primary reformer containing less than 0.3 ppm (vol) peak total sulfur from a feed gas averaging about 0.6 ppm... 

Some natural gases have also been found to contain mercury, which is a reformer catalyst poison when present in sufftciendy large amounts. Activated carbon beds impregnated with sulfur have been found to be effective in removing this metal. 

Iron impregnated on activated carbon was used as catalyst for the direct synthesis of phenol from benzene. The effect of Sn addition to the catalyst was studied. The prepared catalysts were characterized by BET, SEM and XRD analysis. The catalyst 5.0Fe/AC showed good activity in the conversion of benzene and addition of Sn seemed to improve the selectivity of phenol in the reaction. 

Nitrogen adsorption experiments showed a typical t)q5e I isotherm for activated carbon catalysts. For iron impregnated catalysts the specific surface area decreased fix>m 1088 m /g (0.5 wt% Fe ) to 1020 m /g (5.0 wt% Fe). No agglomerization of metal tin or tin oxide was observed from the SEM image of 5Fe-0.5Sn/AC catalyst (Fig. 1). In Fig. 2 iron oxides on the catalyst surface can be seen from the X-Ray diffractions. The peaks of tin or tin oxide cannot be investigated because the quantity of loaded tin is very small and the dispersion of tin particle is high on the support surface. 

In another study, it was shown that the activity of hydrochlorination catalysts made by impregnation of activated carbon with tetrachloroaureate is due to the adsorption of [AuCy anions on the activated carbon [423]. Similar studies, dealing with the adsorption of aurocyanide, [Au(CN)2] , onto activated carbon, have revealed that aurocyanide does not convert to metallic gold up to temperature of about 240°C [424, 425]... 

Be careful to keep track of which side is the active side of the catalyst impregnated carbon cloth. The active side has more of the carbon-platinum binder powder and is smoother. 

Pyrolyzed catalysts obtained by heat treatment in Argon of active carbon impregnated with solution of the compound Co-tetramethoxyphenylporphirine (CoTMPP) are studied [9], Air gas-diffusion electrodes with this catalyst show low polarisation in a wide interval of current densities (up to 100 mA/cm2) and stable long-term performance. These catalysts are more suitable for use in magnesium-air cells operating at high current drains, but unfortunately their price is comparatively high. 

Various carbon-based catalysts were tested in the investigated air gas-diffusion electrodes pure active carbon [6], active carbon promoted with silver [7] or with both silver and nickel. Catalysts prepared by pyrolysis of active carbon impregnated with a solution of the compound Co-tetramethoxyphenylporphyrine (CoTMPP) are also studied [8],... 

The study of catalysts produced by heat treatment in argon of active carbon impregnated with the compound C-tetramcthoxyphcnyiporphyrine (CoTMPP) is of great interest. The polarization curves of air electrodes with... 

Before preparing these carbon-supported Pt-based catalysts, a support pretreatment toward granular activated carbon with an aqueous solution of NaOH (pH 14) was carried out by immersing for 24 h to promote the anion exchange between the ligand chloride of impregnated metal precursers (K2PtCl4) and the aqueous hydroxide ion (OH ) inside the micropores of the activated carbon [33]. 

The feasibility of carbon-supported nickel-based catalysts as the alternative to the platinum catalyst is studied in this chapter. Carbon-supported nickel (Ni/C, 10 wt-metal% [12]), ruthenium (Ru/C, 10 wt-metal% [12]), and nickel-ruthenium composite (Ni-Ru/C, 10 wt-metal%, mixed molar ratio of Ni/Ru 0.25,1,4, 8, and 16 [12]) catalysts were prepared similarly by the impregnation method. Granular powders of the activated carbon without the base pretreatment were stirred with the NiCl2, RuC13, and NiCl2-RuCl3 aqueous solutions at room temperature for 24 h, respectively. Reduction and washing were carried out in the same way as done for the Pt/C catalyst. Finally, these nickel-based catalysts were evacuated at 70°C for 10 h. 

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