Carbon formation solid phase catalyst

Metal-catalyzed cross-couplings are key transformations for carbon-carbon bond formation. The applicability of continuous-flow systems to this important reaction type has been shown by a Heck reaction carried out in a stainless steel microreactor system (Snyder et al. 2005). A solution of phenyliodide 5 and ethyl acrylate 6 was passed through a solid-phase cartridge reactor loaded with 10% palladium on charcoal (Scheme 2). The process was conducted with a residence time of 30 min at 130°C, giving the desired ethyl cinnamate 7 in 95% isolated yield. The batch process resulted in 100% conversion after 30 min at 140°C using a preconditioned catalyst. 

Modification of porous inorganic materials by carbon makes it possible to obtain porous carboniferous composites with high thermal and chemical stability and strength. To introduce carbon into pores, both gas phase pyrolysis and carbonization through thermochemical solid-phase reactions are employed. The formation of carbon structures depends on carbonization conditions process rate, precursor concentration, presence of catalyst, etc. [1-3]. Phenolic resins, polyimides, carbohydrates, condensed aromatic compounds are most widely used as polymeric and organic precursors[4-6]. 

Since the renaissance of solid-phase organic chemistry in 1992, carbon-carbon bond formation reactions on solid support have probably been the best studied reactions. Many different facets of the Suzuki, Heck and Stille reactions have been evaluated. The influence of linkers, catalyst, solvents, microwave, polymer-bound aryl halides or polymer-bound arylboronic acids (or stannanes) have been studied in detail. 

Due to slow kinetics, the conventional heterogeneous catalysis of the dehydrogenation of decalin in the solid-gas phase is performed at temperatures of more than 400 °C, which might result in the formation of by-products or carbonaceous deposit on the catalyst in addition to thermal energy loss. In a recent study, an attempt was made to apply the so-called liquid-film concept to hydrogen evolution from decalin with carbon-supported platinum-based catalysts under reactive distillation conditions in order to obtain high electric power suflficient for PEMFC vehicle operations in the temperature range 200-300°C [236]. 

Depending on the H2S/CH4 ratio, hydrogen sulfide reforming occurs at a temperature higher than 850°C. At these temperatures, the elemental sulfur produced is in the vapor phase and cannot cause deactivation of metal sulfide-based catalysts. However, the formation of solid carbon can be harmful for the catalysts. To avoid coking effect, the molar ratio of H2S/CH4 must be greater than 4. As indicated by thermodynamic analyses [21], a higher H2S/CH4 ratio can reduce carbon formation to zero at lower temperatures. 

The olefin metathesis reaction has been proven to be an extremely useful tool for carbon-carbon bond formation in organic synthesis. Owing to the prevalence of this reaction in the synthetic organic literature, it is not surprising that it has been translated to the solid phase. Several metathesis catalysts, for example, A-C, have been developed and employed on the solid support for various applications (Figure 6.1)." Moreover, in several examples, the solid support affords a mechanism for the differentiation of the olefins, allowing the rapid removal of undesirable side products. 

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