Catalysts Shell catalyst

Third-generation high yield supported catalysts are also used in processes in which Hquid monomer is polymerized in continuous stirred tank reactors. The Hypol process (Mitsui Petrochemical), utilizes the same supported catalyst technology as the Spheripol process (133). Rexene has converted the hquid monomer process to the newer high yield catalysts. Shell uses its high yield (SHAC) catalysts to produce homopolymers and random copolymers in the Lippshac process (130). 

Apart from the above described core-shell catalysts, it is also possible to coat active phases other than zeolite crystals, like metal nanoparticles, as demonstrated by van der Puil et al. [46]. More examples of applications on the micro level are given in Section 10.5, where microreactors and sensor apphcations are discussed. 

In a recent paper we used the temperature sequence of EXAFS measurements of the reduced catalyst In H2 to determine the temperature dependence of the disorder. (7 ) Comparable data was obtained for Ft metal over the same temperature range. The analysis proceeded by fitting the 1st coordination shell catalyst data to a 2-shell model In which the 1st shell was assumed to be that part of the Ft cluster... 

Two ways to reduce the diffusion length in TBRs are 1) use of smaller catalyst particles, or 2) use of an egg-shell catalyst. The first remedy, however, will increase pressure drop until it becomes unacceptable, and the second reduces the catalyst load in the reaction zone, making the loads of the TBR and the MR comparable. For instance, the volumetric catalyst load for a bed of 1 mm spherical particles with a 0.1 mm thick layer of active material is 0.27. The corresponding load for a monolithic catalyst made from a commercial cordierite structure (square cells, 400 cpsi, wall thickness 0.15 mm), also with a 0.1 mm thick layer of active material, is 0.25. 

Subtle electronic effects were also observed for the Sasol ligands, as in the series X = CN, Ph, OBz, Me a decrease in the rate of reaction was found while the linearity followed the reverse trend the better donor gives the highest linear to branched ratio (4.9, very similar to the best Shell catalyst 170 °C, 85 bar). As the authors remarked, this is not an intrinsic ligand effect on the reaction it is a measure of the amount of phosphine-free catalyst 5 that is present in the equilibrium. Thus the weaker donor ligands give more 5 and thus a higher rate and a lower l b ratio. This was supported by IR and NMR measurements. 

Cargnello, M., et al., Multiwalled carbon nanotubes drive the activity of metal oxide core-shell catalysts in modular nanocomposites. Journal of the American Chemical Society, 2012. 134(28) p. 11760-11766. 

The 10% Ft ML core-shell catalysts were tested in an MEA and gave satisfactory performance with 10 ppm CO in H2 with an electrode loading of 0.018 mg Ft cm-. i A similar surface modification of a Ft core with Ru has been investigated by Crabb et al. They reported that, on reduction, a surface FtRu alloy formed and showed similar CO tolerance to a conventional nanoparticle FtRu alloy. 

Nanowire-Based Three-Dimensional Hierarchical Core/Shell Catalyst Layer... 

Aliphatic polyketones are made from the reaction of olefin monomers and carbon monoxide using a variety of catalysts. Shell commercialized a terpolymer of carbon monoxide, ethylene, and a small amount of propylene in 1996 under the trade name Carilon (structure 4.79). They have a useful range between the Tg (15°C) and (200°C) that corresponds to the general useful range of temperatures for most industrial applications. The presence of polar groups causes the materials to be tough, with the starting materials readily available. 

Figure 6.21. Schematics of currently pursued Pt-based electrocatalyst concepts for the ORR. (A) Pt bulk alloys (B) Pt alloy monolayer catalyst concepts (C) Pt skin catalyst concept (D) De-alloyed Pt core-shell catalyst concept.

To demonstrate the potential available, simulations were carried out for the oxidation of carbon monoxide on a palladium shell catalyst with water desorption from 3A zeolite as a heat sink, based on experimentally validated model parameters for the individual steps (Figure 16). The calculations indicated that the reaction cycle time could be lengthened by a factor of 10, to a total 20 minutes, in comparison to a simple regenerative process with a similar amount of inert material instead of adsorbent in the fixed bed and for the same threshold for temperature deviation from the initial value. 

Data are also presented in this paper which describe the results of a solvent boiling range study when processing SRC-I. A run was also made to establish a thermal baseline wherein the SRC-I was processed over an inert 1/32 inch Shell catalyst support. 

Thermal Baseline Study. PDU Run 2LCF-21 (Thermal Baseline) processed a 70/30 volume percent SRC-I/500°F IBP KC-Oil feed blend over an inert 1/32 inch Shell catalyst support. The inert support was the extrudate base for the modified Shell 324 catalyst and had been calcined at 1100-1150°C. The purpose of this run was to determine the extent of conversion and denitrogenation in the absence of an active catalyst ingredient - nickel and molybdenum (Ni/Mo). 

In this work we present hyperbranched polymers as platforms for catalysts that fall into three major classes, according to their topology and binding mode to the polymeric support (Fig. 2) (i) defined multiple site catalysts (ii) dendritic core-shell catalysts (iii) supramolecular catalyst complexes. 

The catalyst plays a crucial role in technology. Previously, catalysts were based on palladium of 1 to 5 wt% impregnated on silica with alkali metal acetates as activators. Modern catalysts employ as enhancers noble metals, mostly gold. A typical Bayer-type catalyst consists of 0.15-1.5 wt% Pd, 0.2-1.5 wt% Au, 4-10 wt% KOAc on spherical silica particles of 5 mm diameter [14], The reaction is very fast and takes place mainly inside a thin layer on the particle surface (egg-shell catalyst). 

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