Bench-scale feasibility studies

Foster Wheeler Corporation s efforts toward full commercialization of this process are extended in the framework of a three phase program of process research and bench-scale feasibility studies, pilot plant operation, and large scale demonstration. Only the conclusions directly pertaining to the process are discussed here. A detailed discussion of the mechanism and kinetics of this rather involved system is beyond the scope of this paper and will be reported at a later date. 

Research and Bench-Scale Feasibility Studies. The reaction between carbon and sulfur dioxide at elevated temperatures is well known and has been used for numerous processes. For example, sulfur was produced at Trail, British Columbia from 1935 to 1943 by blowing sulfur dioxide and oxygen into the bottom of a coke-fired reduction furnace. Coke was charged at the top and ash was removed on a rotary grate at the bottom of the furnace. The hot zone of the furnace was kept at 1300°C to maintain rapid reaction rates and smooth operation. Sufficient sulfur dioxide was added to the gas to react with the carbon monoxide and carbon oxysulfide contained in the reduction furnace off-gas. Coal was con-... 

The next step towards successful development of the SF extraction process is to move from small-scale investigations to bench scale feasibility studies. Bench-scale data will provide information to evaluate process design issues and to establish the utility of this technology. Key conqwnents of this technology that must be evaluated are (a) ligand solubility in SC COj. (b) metal ion extraction into SC CO2, (c) metal chelate solubility in SC CO2, and (d) metal ion recovery from a metal-laden SC CO2 phase. Hie overall goal of the SFE process is the concentration of the contaminants, as depicted in Hgure 6. 

The hydrogenation of enamides and enol acetates without acid function is often more demanding, and at present is not applied widely. Besides a bench-scale application by Roche with a Ru-biphep catalyst [55], two examples are of interest a pilot process for a cyclic enol acetate by Roche [55], and a feasibility study by Bristol-Myers Squibb [56], both using Rh-DuPhos catalysts (Fig. 37.11). In the latter case, despite very good ee-values, a chiral pool route was finally chosen. Chiral Quests Rh-f-KetalPhos (see Fig. 37.9) has been shown to hydrogenate a variety of substituted aryl enamide model substrates at r.t., 1 bar, with very promising catalyst performance (ee 98-99%, TON 10000) [47]. 

The Bench Scale Investigations of the sulfur-iodine cycle include a system which was planned to study the cycle under continuous operation conditions and a smaller unit, the Closed Loop Cycle Demonstrator, aimed at a simple demonstration of the feasibility of the cycle in a closed loop using recycled materials. 

The SO2 recovery process is being studied in both bench-scale and fiuid-bed pilot equipment (1,2,3). Initial feasibility tests were conducted in small fixed-bed reactors to determine the most effective carbon for SO2 removal and to evolve the regeneration sequence for minimum carbon loss. Continuous operation of the various process steps was evaluated under simulated conditions in fiuidized-bed pilot equipment. 

Process studies on fluoride volatility method have been carried out for the purpose of evaluating feasibility for the reprocessing of FBR fuels (33). Process concept investigated is shown in Figure 9. It aimed at a simple and advanced process for continuous operation. Experiments are mainly made on the fluorination and purification using bench-scale fluid-beds and traps. 

A bench-scale test facility for hydrogen production using the thermochemical iodine-sulfur (IS) process has been established at JAERI to verify the hydrogen production, to study the conditions for the reactions, and to gain experience for a large-scale plant [74]. The three reactions (see appendix A.2.3.) are performed in separate sections of the apparatus, the Bunsen reaction and the sulfuric acid decomposition at the same time to avoid SO2 storage (see Fig. 4-8). The process requires temperatures of 800 to 900 °C. Its feasibility was successfully demonstrated in a glass, quartz, and teflon lab-scale apparatus. In the course of six cycles completed, the total amounts of H2 and O2 produced were 16.4 1 and 9.9 1, respectively. The thermal efficiency achieved, however, was much smaller than the theoretical one of 47 - 50 % [44]. In late 1997, the continuous operation of the IS process cycle as a closed loop over 48 h resulted in the production of 44.8 1 of H2 [75]. 

A bench-scale process was reported by Merck [114] for the hydrogenation of an ot,p-unsaturated ester (Fig. 17) for the synthesis of a D2 (DP) receptor antagonist and operated on a 5-kg scale. The potential of Ir/P N catalysts was demonstrated in a feasibility study by DSM in collaboration with Pfaltz [115] for the hydrogenation of y-tocotrienyl carried out with the pyridinyl phosphinite depicted in Fig. 16. The hydrogenation of the two prochiral C=C bonds occurs with excellent stereoselectivity to give almost exclusively the (R,R,R) product. The existing stereogenic center does not influence the reaction. 

Remediation of TNT-contaminated soil by R chrysosporium has also been observed (30, 82). In a bench scale (1.0-2.0 kg soil) feasibility study (82), TNT was degraded from 200 and 2,000 mg/kg (Fig. 10) to nondetectable levels within 14 and 100 days, respectively. In another microcosm, the TNT concentration was reduced from 10,000 to 3,500 mg/kg in 100 days. The principal metabolites were the isomeric aminodinitrotoluenes, which reached maximum concentrations of 35, 280 and 2,600 mg/kg on days 14, 35 and 55 for the 200, 2,000 and 10,000 mg/kg microcosms. These metabolites decreased to less than 10 mg/kg by day 28 in the 200 mg/kg microcosms and to 80 and 1,000 mg/kg by day 100 in the 2,000 and 10,000 mg/kg microcosms, respectively. The ultimate fate of the TNT in the microcosms was not explored. Because the microcosms were open systems, no radioactive labeling was possible. However, Fernando et al. (30) observed that in soil contaminated with 10,000 mg/kg TNT approximately 20% of the TNT was converted to CO2 within 90 days. They reported that 11.5% of the radioactivity was bound to a soil-corn cob-fungal matrix. 

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