SPE reactor

Fig. 12.2 Plate-and-frame electrolyser schemes (a) undivided cell (b) membrane-divided cell (c) solid polymer electrolyte (SPE) reactor (d) membrane-divided cell with GDE (e) SPE-GDE reactor. Liquid compartments are denoted in grey...

The fundamental principle of SPE reactors is the coupling of the transport of electrical charges, i.e. an electrical current with a transport of ions (cations or anions), through a SPE membrane due to an externally applied (e.g. electrolysis) or internally generated (e.g. fuel cells) electrical potential gradient. For example, in a chlorine/alkaline SPE reactor (Fig. 13.3), the anode and cathode were separated by a cation-SPE membrane (e.g. Nafion 117) forming two compartments, containing the anolyte (e.g. 25 wt% NaCl solution) and the catholyte (e.g. dilute sodium hydroxide), respectively. 

FIGURE 26.20 Schematic diagram of the SPE reactor for edible oil hydrogenation using either water of H2... 

Onder E, Koparal A S and Ogutveren U B (2009), Electrochemical treatment of aqueous oxalic acid solution by using solid polymer electrolyte (SPE) reactor , Chem Eng J, 147,122-129. 

Reaction in a Centrifugal Pump In the reaction between acetic acid and gaseous ketene to make acetic anhydride, the pressure must be kept low (0.2 atm) to prevent polymerization of ketene. A packed tower with low pressure drop could be used but the required volume is very large because of the low pressure. Spes (Chem. Ing. Tech., 38, 963-966 [1966]) selected a centrifugal pump reactor where... 

In NAA the sample is made radioactive by subjecting it to a high dose (days) of thermal neutrons in a reactor. The process is effective for about two-thirds of the elements in the periodic table. The sample is then removed in a lead-shielded container. The radioisotopes formed decay by B emission, y-ray emission, or X-ray emission. The y-ray or X-ray energies are measured by EDS (see Chapter 3) in spe-... 

HPLC methods can be ntilized for the pre-concentration of aromatic amines from polluted waters on silica gel or octadecyl silica (ODS) colnmns [55], The determination is then performed by RP HPLC using ODS packings as the stationary phases and a mixture of methanol, isopropanol, and water as the mobile phase [55], RP HPLC with diode array detector (DAD) methods coupled on-line with a continnons seqnential anaerobic/aerobic reactor system have been employed in wastewaters treatments [56], A continnons monitoring of the possible presence of aromatic amines in azo dyes wastes is based on indncing in the waste, the reaction of a reduction of the dye, followed by HPLC/ UV or HPLC/MS analysis [57-59], The redncing agent solutions are sodium dithionite or tin(II) chloride in an aqneons acidic medinm at 70°C, followed by SPE [58,59], LLE [60,61], or SEE [60-62],... 

In addition to the high-pressure assembly, the modified system incorporates a new real-time data collection system coupled with a PC based computer. Experimental parameters, such as the valve firing sequence and the reactor temperature-control program, can be set from the computer. Reactants are introduced through two high-spe pulse valves or two continuous feed valves that are fed by mass flow controllers. In high-speed transient response experiments, the QMS is set at a particular mass value and the intensity variation as a function of time is obtained. In steady-flow experiments. 

Y. Lu, J. A. Biesenberger, and D. B. Todd, A Backmix Drag-flow Reactor, SPE. ANTEC, Tech. Papers, 51, 27-29 (1993) also Y. Lu, J. A. Biesenberger, and D. B. Todd, Continuous Polymerization in a back-mixed Drag Flow reactor, SPE. ANTEC Tech. Papers, 52, 113-115 (1994). 

Fig. 2 A microwave-assisted fluorous synthesis system, microwave reactor (left), plate-to-plate SPE (middle), and a plate centrifuge unit (right)...

The integration of microwave heating and fluorous technologies has generated a powerful solution to address both the reaction and separation issues in parallel and combinatorial synthesis. With the further development of multimode microwave reactors for plate reactions and F-SPE for plate-to-plate separations, microwave-assisted fluorous synthesis will play an even more important role in compound library synthesis. 

Despite their intrinsic simplicity, the plate-and-frame reactors require accurate selection of the materials, especially when the electrolytic processes are performed in non-aqueous solvents and/or deal with substrates which are currently used as solvents, as in the case of volatile organic chlorides. Special attention should be paid to the selection of the gaskets, for long-term operational stability. Moreover, in the case of the SPE scheme, porous electrodes should be adopted, to allow for optimal contact between electrode, electrolyte and reactants/products. In this case, mass-transfer limitations into the porous structure should be carefully considered. 

The central part of the electrochemical HDH reactor is the use of solid polymer electrolyte (SPE). A typical membrane material belongs to the fully fluorinated polyethene-based family polytetrafluoroethylene (PTFE) (known by the trade name Teflon), shown in Fig. 13.1. 

The reactor can be operated in a batch recycle mode. One of the advantages of SPE HDH technology is that separation and recycling of a supporting electrolyte are unnecessary, which can greatly reduce process cost. 

Figure 13.6 shows the principle of the SPE HDH reactor using a Nation 117 membrane to separate anolyte and catholyte chambers. 

The SPE HDH reactor is flexible in terms of structural materials and functions, e.g. electrode materials could be mesh- or carbon-supported gas diffusion ones the SPE could be a cation or anion exchange membrane (e.g. Nafion 117 or Fu-MATech FT-FKE-S) and the reactor can treat either aqueous or non-aqueous (e.g. a paraffin oil) wastes with or without supporting electrolytes. 

Figure 13.8 shows the effect of cathode catalysts on the HDH of an aqueous saturated PCP solution in the SPE HDH reactor. 

Figure 8 CP (1 ms contact time) and SPE NMR spectra of the coke concentrate f rom FCC catalyst deactivated using n-hexadecane in the fluidised-bed reactor.

Synthesis of pure hydrogen peroxide using solid polymer electrolytes (SPE) could eliminate the need to separate the product from liquid electrolytes (basic or acidic). Designs of the (SPE) fuel cell type of reactor could be investigated for such a process. Tatapudi and Fenton [71, 80] demonstrated the basic feasibility of this process (with or without concurrent anodic ozone evolution). However, new cathode materials and... 

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