Reactions heterogeneous hydrogenation catalyst

The SRC-II process, shown in Figure 2, was developed in order to minimise the production of soHds from the SRC-I coal processing scheme. The principal variation of the SRC-II process relative to SRC-I was incorporation of a recycle loop for the heavy ends of the primary Hquefaction process. It was quickly realized that minerals which were concentrated in this recycle stream served as heterogeneous hydrogenation catalysts which aided in the distillate production reactions. In particular, pyrrhotites, non stoichiometric iron sulfides, produced by reduction of iron pyrite were identified as being... 

A heterogeneous hydrogenation catalyst enabling the reduction of acetone to propane was prepared from the cluster [Os3Ni(//-H)3Cp(CO)9] supported on Chro-mosorb-P and thermally treated under A multi-step reaction pattern was... 

Arene Hydrogenation Although heterogeneous hydrogenation catalysts such as Rh/C readily reduce arenes, none of the homogeneous catalysts discussed up to now are effective for this reaction. A few homogeneous catalysts have been found, however, of which (Ti -allyl)Co P(OMe)3 3 is the best known. When benzene is reduced with this catalyst using Dj, the all-cis isomer of is obtained, and no propane or propane is formed. This... 

Nevertheless, care should be taken if high amounts of sulfur are present in the reaction mixture because sulfur may lead to trouble in the workup. Thus, sulfur compounds may be carried into the hydrogenation reactors together with the aldehydes and poison the heterogeneous hydrogenation catalysts. 

Heterogeneous hydrogenation catalysts typically involve finely divided platinum, palladium, nickel, or rhodium deposited on the surface of powdered carbon (charcoal). Hydrogen gas introduced into the atmosphere of the reaction vessel adsorbs to the metal by a chemical reaction where unpaired electrons on the surface of the metal pair with the electrons of hydrogen (Fig. 7.10a) and bind the hydrogen to the surface. The collision of an alkene with the surface bearing adsorbed hydrogen causes adsorption of the alkene as... 

Diisopropjibenzenes (DIPB) are readily obtained via Eriedel-Crafts alkylation of benzene or cumene by propylene. This reaction inhquid phase has not evolved drastically since 1980 with the exception of the large variety of heterogeneous acid catalysts that are now being used, mainly zeoHtes, type HZSM-12, giving a para/meta ratio = 0.7 (4). In fact, propylene can also be replaced by isopropyl alcohol coming from the hydrogenation of acetone that... 

The most common heterogeneous catalytic reaction is hydrogenation. Most laboratory hydrogenations are done on liquid or solid substrates and usually in solution with a slurried catalyst. Therefore the most common batch reactor is a stirred vessel, usually a stirred autoclave (see Figure 2.1.1 for a typical example). In this system a gaseous compound, like hydrogen, must react at elevated pressure to accelerate the process. 

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]. 

A brief summary of current and potential processes is given in Table 8.1. As shown in the table, most of the reactions are hydrolysis, hydrogenolysis, hydration, hydrogenation, oxidation, and isomerization reactions, where catalysis plays a key role. Particularly, the role of heterogeneous catalysts has increased in this connection in recent years therefore, this chapter concerns mostly the application of heterogeneous solid catalysts in the transformation of biomass. An extensive review of various chemicals originating from nature is provided by Maki-Arvela et al. [33]. 

Enichem made one of the most important steps forward in the development of general heterogeneous oxidation catalysts in the early 1990s with the commercialization of titanium silicate (TS-1) catalysts. TS-1 has a structure similar to ZSM-5 in which the aluminium has been replaced by titanium it is prepared by reaction of tetraethylorthosilicate and tetra-ethylorthotitanate in the presence of an organic base such as tetrapropy-lammonium hydroxide. This catalyst is especially useful for oxidation reactions using hydrogen peroxide (Scheme 4.11), from which the only byproduct is water, clean production of hydroquinone being one of the possibilities. 

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