Incipient wetness

The much more stable MIL-lOO(Cr) lattice can also be impregnated with Pd(acac)2 via incipient wetness impregnation the loaded catalyst is active for the hydrogenation of styrene and the hydrogenation of acetylene and acetylene-ethene mixtures to ethane [58]. MIL-lOl(Cr) has been loaded with Pd using a complex multistep procedure involving an addition of ethylene diamine on the open Cr sites of the framework. The Pd-loaded MIL-lOl(Cr) is an active heterogeneous Heck catalyst for the reaction of acrylic acid with iodobenzene [73]. 

Fig. 5 Comparison of nitrobenzene conversion and aniline selectivity as a function of reaction time for the incipient wetness catalyst [20]...

A 20 wt% of Co/TiOa was prepared by the incipient wetness impregnation. A designed amoimt of cobalt nitrate [Co(N03) 6H20] was dissolved in deionized water and then impregnated onto TiOj containing various ratios of rutileianatase obtained from above. The catalyst precursor was dried at 110°C for 12 h and calcined in air at 500°C for 4 h. 

A 5 wt.% CoOx/Ti02 catalyst was prepared via an incipient wetness technique in which an aqueous solution of Co(N03)2 6H20 (Aldrich, 99.999%) was impregnated onto a shaped Ti02 (Milleimium Chemicals, commercially designated as DT51D, 30/40 mesh), as described in detail elsewhere [6]. Other supported metal oxide catalysts, such as FeOx, CuO, and NiOx, were obtained in a fashion similar to that used for preparing the CoO, catalyst. 

Figure 2 schematically presents a synthetic strategy for the preparation of the structured catalyst with ME-derived palladium nanoparticles. After the particles formation in a reverse ME [23], the hydrocarbon is evaporated and methanol is added to dissolve a surfactant and flocculate nanoparticles, which are subsequently isolated by centrifugation. Flocculated nanoparticles are redispersed in water by ultrasound giving macroscopically homogeneous solution. This can be used for the incipient wetness impregnation of the support. By varying a water-to-surfactant ratio in the initial ME, catalysts with size-controlled monodispersed nanoparticles may be obtained. 

Catalysts were prepared on various supports. One example was a Calgon 120% CTC coconut carbon. The impregnation volume of metal solution was calculated using the measured incipient wetness of the support 0.85 cc liquid per gram of carbon for the... 

More information on the nature of active sites was obtained using some model catalysts obtained by incipient wetness impregnation of a commercial silica (Si-1803 with surface area = 300 nP g ). A preliminary test performed using the support (Table 39.6) showed a very low selectivity to MDB, with the preferential formation 2-EMP, indicating that acid sites alone are not able to promote the cyclization of the intermediate. 

It was prepared by incipient wetness impregnation using Co(N03)2, 6H20, 99.9%, as cobalt precursor. Silica Aerosil 380 was purchased from Degussa. The sample was then dried at 573 K (300°C) and subsequently calcined at 773 K (500°C) under synthetic air. The quantity of cobalt introduced was 2wt.%. 

Catalysts - A commercial Raney nickel (RNi-C) and a laboratory Raney nickel (RNi-L) were used in this study. RNi-C was supplied in an aqueous suspension (pH < 10.5, A1 < 7 wt %, particle size 0.012-0.128 mm). Prior to the activity test, RNi-C catalyst (2 g wet, 1.4 g dry, aqueous suspension) was washed three times with ethanol (20 ml) and twice with cyclohexane (CH) (20 mL) in order to remove water from the catalyst. RCN was then exchanged for the cyclohexane and the catalyst sample was introduced into the reactor as a suspension in the substrate. RNi-L catalyst was prepared from a 50 % Ni-50 % A1 alloy (0.045-0.1 mm in size) by treatment with NaOH which dissolved most of the Al. This catalyst was stored in passivated and dried form. Prior to the activity test, the catalyst (0.3 g) was treated in H2 at 250 °C for 2 h and then introduced to the reactor under CH. Raney cobalt (RCo), a commercial product, was treated likewise. Alumina supported Ru, Rh, Pd and Pt catalysts (powder) containing 5 wt. % of metal were purchased from Engelhard in reduced form. Prior to the activity test, catalyst (1.5 g) was treated in H2 at 250 °C for 2 h and then introduced to the reactor under solvent. 10 % Ni and 10 % Co/y-Al203 (200 m2/g) catalysts were prepared by incipient wetness impregnation using nitrate precursors. After drying the samples were calcined and reduced at 500 °C for 2 h and were then introduced to the reactor under CH. 

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