Supports Norit

The catalyst was prepared by impregnation of the powdered activated carbon support, Norit SX Ultra, (surface area 1200 m g ) with sufficient palladium nitrate to produce a metal loading of 3 %. The resulting suspension was dried and calcined at 423 K for 3 hours. The dispersion of the catalyst was... 

Platinum catalysts were prepared by ion-exchange of activated charcoal. A powdered support was used for batch experiments (CECA SOS) and a granular form (Norit Rox 0.8) was employed in the continuous reactor. Oxidised sites on the surface of the support were created by treatment with aqueous sodium hypochlorite (3%) and ion-exchange of the associated protons with Pt(NH3)42+ ions was performed as described previously [13,14]. The palladium catalyst mentioned in section 3.1 was prepared by impregnation, as described in [8]. Bimetallic PtBi/C catalysts were prepared by two methods (1) bismuth was deposited onto a platinum catalyst, previously prepared by the exchange method outlined above, using the surface redox reaction ... 

The carbon support used was a Norit activated carbon (RX3 extra) having a surface area of 1190 m2.g 1 and a pore volume of 1.0 cm3.g . The Co/C catalyst (4.1 wt% Co) was prepared by pore volume impregnation with an aqueous solution of cobalt nitrate (Merck p.a.) followed by drying in air at 383 K (16 h). The promoted catalyst (1.5 wt% Co, 7.7 wt% Mo) was prepared in a special way to ensure a maximum amount of the Co-Mo-S phase (11). Mossbauer spectroscopy of this promoted catalyst clearly showed that only the Co-Mo-S phase was present after sulfiding (11) and furthermore that this Co-Mo-S is probably a Co-Mo-S type II phase, meaning a minor influence of active phase-support interaction (11,12). The catalytic activity of the sulfided catalysts was determined by a thiophene HDS measurement at 673 K and atmospheric pressure, as described elsewhere (10). The thiophene HDS reaction rate constant kHDg per mol Co present (approximated as a first order reaction) was found to be 17 10 s 1 for Co/C and 61 10 3s 1 for Co-Mo/C. 

The activated carbons used as supports were ROX-0.8 and GF-45 (from Norit), and ROX-N and GF-N (obtained from ROX-0.8 and GF-45 by oxidation with HNO3 35%). Characterization of these carbons is reported in a previous publication [15]. 

Carbon-supported (Activated carbon SXplus supplied by NORIT, Sbet = 750 m2.g-l, particle size 0.2-0.1mm) bimetallic and monometallic catalysts were prepared by deposition from a suspension of carboxylate particles in n-heptane chosen as inert organic solvent. Precursors used for the incorporation of the metals were either, palladium(II) acetate (ACROS) and bismuth(lll) oxoacetate, Bi0(02CCH3) (synthesized as described elsewhere [8]), or diammine(pyrazine-2,3-dicarboxylato-N,0)palladium(II) [12] and tris(monohydrogenopyrazine-2,3-dicarboxylato)bismuth(III) (noted Bi(2,3-pzdcH>3) [13]. 

An activated carbon supplied by NORIT was used as support. It corresponds to the trade name PKDA 10X30 (Sbet = 550 m2.g-l) and is noted hereafter Cq. Its selected particle size is in the range 0.1-0.05 mm. 

Van Wingerden and co-workers " obtained the EXAFS spectra around the Co K edge for 5,10,15,20-tetra-(p-chloro-phenyl)porphyrinatocobalt(III) supported on Norit BRX and heated in nitrogen to various temperatures up to 850° C. This study was geared to an understanding of the enhanced catalytic effect towards oxygen reduction that accompanies heat treatment. 

The support used was an activated carbon supplied by NORIT (SX+, 50-100 pm). It was oxidised by nitric acid as follows 6 g of SX+ was stirred in boiling 2.5 mol/L HNO3 (150 mL) during 24 h. After treatment, the carbon was removed by filtration and washed with distilled water on a Soxhlet extractor for 24 h, then dried under vacuum at 50°C for 4 h [5]. 

The authors acknowledge financial support fi-om the Belgian National Fund for Scientific Research (F.N.R.S., Brussels). They also wish to thank Didier Desmecht for the realization of some catalytic tests and for technical assistance, and the NORIT company for supplying the carbon support. 

Fuente et al. [27] compared two activated carbons of Norit with similar oxygen content and p/f but different pore volumes (i.e., 0.522 mL/g vs. 0.393 mL/g). Loading these supports with either H2PtCl6 or [Pt(NH3)4]Cl2 resulted in 1 wt% Pt on the high-pore-volume support, with a dispersion of 35% irrespective of the precursor. The low-pore-volume material resulted in metal loading of about... 

Cabot Norit Activated Carbon Euro Support Catalysts Kortegracht 26 3811 KH Amersfoort The Netherlands... 

Fig. 23 Ethylbenzene formation with different Pd supported catalysts. Filled square represents Pd MOF-5 (1 wt%), open circle represents Pd/Norit A (1 wt%) and open triangle represents Pd/C (purchased from Aldrich, wt%[51]. Reproduced with permission ofThe Royal Society of Chemistry...

Most of the examples of metal MOFs and metaloxides MOFs discussed up to now have been synthesized in order to obtain novel kinds of supported nanoparticles with potentially advantageous properties for applications in catalysis. The catalytic properties of the composite materials Pd MOF-5 and Cu MOF-5 were among the first to be tested. The Pd MOF-5 composite that was obtained by the gas phase loading/photolysis synthetic protocol (35.6 wt% Pd) showed moderate activity in catalysis of hydrogenation of cyclooctene [59], The Pd MOF-5 (1 wt%) synthesized by the incipient wemess technique from [PdCacac) ] was tested as catalyst in hydrogenation of styrene, 1-octene and c/x-cyclooctene, and exhibited a shghtly higher catalytic activity than Pd supported on activated carbon (Pd/Norit A Fig. 23) [51]. 

The process is carried out in the gas phase at a temperatures above 160°C. The reaction is exothermic, so heat control in the production process is important. Vinylacetate is used as intermediate in a large number of production processes. The catalysts can be produced by impregnation of an activated carbon with zinc acetate, followed by drying. The zinc concentration is in the order of 11 up to 13%. The optimal activated carbon support is a high steam activated and acid washed 3 or 4 mm extrudate like the NORIT RX 3 EXTRA or NORIT RX 4 EXTRA. Important characteristics of the impregnated carbon are ... 

The main catalyst FeCls reacts with the alcohol forming FezOs, which lowers the activity. CuCk is used as co-catalyst and regenerates the main catalyst. HF regenerates the co-catalyst. For this application relatively low steam activated extrudates are applied as support. The NORIT R 2 or RB 2 as mentioned in Figure 3 have the desired porosity. 

Other new developments are the conversion of waste CFC-12 (CCI2F2) into high added value product CH2F2 (HFC-32) [19,20]. Also other CFC s can be converted according to the same reaction mechanism For this conversion a Pd supported catalyst is used. As support a very pure steam activated carbon with a relatively low activation degree is selected. Washed NORIT RB 2 fulfill the requirements. 

The mesoporous carbon xerogel support (X25) was submitted to an oxidative treatment using HNO3 in order to increase the amonnt of oxygenated surface functions. Such treatments were previously studied using a microporous activated carbon (SX+) supplied by NORIT (Sbet 920 m. g ) [2],... 

The authors wish to thank the PAIINANOMAT, and FNRS for financial support and the NORIT firm for supplying the SX+ carbon. 

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