Hydrocarbons hydrothermal synthesis

Silicalite membrane useful for separation of n-Hexane and branched hydrocarbon (MP, DMB) at 100 - 300°C. 2 step hydrothermal synthesis (Evolutionary selection mechanism) of zeolite membrane has improved to create perfect zeolite layer. Hexane nano-permporosimetry technique determined pore size range 1 to 20 nm. The instrument was also found to be useful tool to confirm the membrane quality. 

This chapter discusses the synthesis, characterization and applications of a very unique mesoporous material, TUD-1. This amorphous material possesses three-dimensional intercoimecting pores with narrow pore size distribution and excellent thermal and hydrothermal stabilities. The basic material is Si-TUD-1 however, many versions of TUD-1 using different metal variants have been prepared, characterized, and evaluated for a wide variety of hydrocarbon processing applications. Also, zeolitic material can be incorporated into the mesoporous TUD-1 to take the advantage of its mesopores to facilitate the reaction of large molecules, and enhance the mass transfer of reactants, intermediates and products. Examples of preparation and application of many different TUD-1 are described in this chapter. 

Because carbon has a natural affinity for adsorption of heavy hydrocarbon species and polar molecules, CMS membranes need to be used at a sufficiently high temperature to eliminate contribution/interference of the adsorption. In contrast, strong adsorption of heavier molecules may be used to separate those species by adsorption as discussed earlier by the SSF mechanism (Rao and Sircar, 1993b). The SSF carbon membranes typically have pore dimensions much greater than those needed for CMS membranes since the separation is based on the adsorbed species effectively blocking permeation of other components (Fuertes, 2000). Carbon membranes are resistant to contaminants such as H2S and are thermally stable and can be used at higher temperatures compared to the polymeric membranes. For the synthesis gas environment, the hydrothermal stability of carbon in the presence of steam will be a concern limiting its operation temperature. 

Titanium has been introduced into zeolite frameworks in order to prepare catalysts which are both active and selective for oxidation of hydrocarbons with H2O2. Catalysts of this type are suited for fine chemical production, as product waste will be minimized. Starting materials for Ti-modified zeolites were ZSM-5 (TS-1),ZSM-11 (TS-2),ZSM-48 and zeolite beta. Echchahed et al. [66] investigated the synthesis of TS-1 under variation of hydrothermal time and temperature. The change in the UV band with maximum at 208 nm, typical of tetrahedral Ti, which broadens with growing titanium incorporation, is explained by the... 

Hydrothermal carbonization is an effective method and has been extensively studied for the synthesis of carbonaceous material from different organic sources, especially from biomass. Pyrolysis is one of the most promising thermochemical processes for the conversion of biomass mainly into liquid (bio-oil), gaseous (gaseous C1-C4 hydrocarbons), and solid (char) products [167,168]. 

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