Supercritical water applications

This can be used for the decomposition of chemical weapons. Another application is that the supercritical water is a special reaction medium to synthesize the new advanced materials and medicines. There appeared several reviews on the chemistry and application of supercritical water [62-66]. 

Superheated and supercritical water are used in several applications. Supercritical water is most often used in the destruction of organic wastes, including some chemical warfare agents, as an alternative to incineration (Katritzky et al., 1996 Sherman et al., 1998). Recent reports describe the use of both forms as a solvent and as a reactant in synthetic chemistry (Katritzky et al., 1996 An et al., 1997). Some of the reactions investigated include metal-mediated alkyne cyclizations, Pd-catalyzed al-kene arylations, aldol reactions, the Fischer indole synthesis, and hydrolysis reactions. Waterborne coatings and the destruction of wastes in supercritical water are fully... 

Supercritical Water Oxidation (SCWO). Application to industrial wastewater treatment... 

R.W. Shaw and N. Dahmen, Destruction of Toxic Organic Materials using Supercritical Water, Supercritical Fluid Fundamentals and Applications, E. Kiran Ed., 425 NATO ASI, Blackie Academic (2000). 

P.C. Dell Orco, E.F. Gloyna, S. Buelow, Oxidation Processes in the Separation of Solids from Supercritical Water, Supercritical Fluids Engineering Science, Fundamentals and applications, ACS Symposium Series, 514, (1993), 314. 

Initial studies of phenol SCWO Involved in extensive SCWO study Investigated the unique features of supercritical water in terms of density, dielectric constant, viscosity, diffusivity, electric conductance, and solvating ability Treatment of hazardous organic compounds Application of SCWO to the decomposition of sludges Found that sludge readily decomposes at near-critical water conditions with 02 or H202 as an oxidant in a batch or continuous flow reactor Treatment of sludges... 

Fahing et al. [176] studied the effect of the addition of modifiers such as methanol and water on the SCFE of organic solutes from soils and clays. Hawthorne et al. [177] compared the application of sub- and supercritical water in the extraction of organics from soil, and found that both were effective extractants. 

The cost of transporting wood chips by truck and by pipeline as a water slurry was determined. In a practical application of field delivery by truck of biomass to a pipeline inlet, the pipeline will only be economical at large capacity (>0.5 million dry t/yr for a one-way pipeline, and >1.25 million dry t/yr for a two-way pipeline that returns the carrier fluid to the pipeline inlet), and at medium to long distances (>75 km [one-way] and >470 km [two-way] at a capacity of 2 million dry t/yr). Mixed hardwood and softwood chips in western Canada rise in moisture level from about 50% to 67% when transported in water the loss in lower heating value (LHV) would preclude the use of water slurry pipelines for direct combustion applications. The same chips, when transported in a heavy gas oil, take up as much as 50% oil by weight and result in a fuel that is >30% oil on mass basis and is about two-thirds oil on a thermal basis. Uptake of water by straw during slurry transport is so extreme that it has effectively no LHV. Pipeline-delivered biomass could be used in processes that do not produce contained water as a vapor, such as supercritical water gasification. 

In addition to these cost elements, transport of biomass for a direct combustion application by water creates a prohibitive drop in the LHV of the fuel because of absorbed water. These issues limit the application of pipeline transport of biomass to large applications that use oil as a carrier medium, or that supply a process for which the heat content of the fuel is not degraded by the requirement to remove absorbed water as vapor, such as a supercritical water gasification process. 

Another important bulk chemical that could be derived from glycerol is acrylic acid (Craciun et al., 2005 Shima and Takahashi, 2006 Dubois et al., 2006). Shima and Takahashi (2006) reported a complete process for acrylic acid production involving the steps of glycerol dehydration in a gas phase followed by the application of a gas phase oxidation reaction to a gaseous reaction product formed by the dehydration reaction. Dehydration of glycerol could lead to commercially viable production of acrolein, which is an important and versatile intermediate for the production of acrylic acid esters, superabsorber polymers or detergents (Ott et al., 2006). Sub- and supercritical water have been applied by Ott et al. (2006) as the reaction media for glycerol dehydration, but the conversion and acrolein selectivities that have been achieved so far are not satisfactory for an economical process. 

Supercritical Water Oxidation Meeting. Achievements and Challengers in Commercial Applications. Aug 14-15, 2001, Arlington, VA. 

---