Microautoclave

In addition to continuous bench-scale work, CCDC carried out a rather extensive laboratory program involving the use of the microautoclave reactor. The program developed tests to compare the activities of different solvents. These tests quickly evaluated a solvent so that the performance under coal liquefaction conditions could be predicted. The tests are now used at the Wilsonville SRC Pilot Plant as a means of determining when stable operation has been achieved. 

The microautoclave solvent activity tests measure coal conversion in a small batch reactor under carefully controlled conditions. The tests are described as Kinetic, Equilibrium and SRT. The Kinetic and Equilibrium Tests measure coal conversion to tetrahydrofuran solubles at conditions where conversion should be monotonically related to hydrogen transfer. The Kinetic Test is performed at 399°C for 10 minutes at an 8 to 1 solvent to coal ratio. The combination of high solvent ratio and low time provide a measure of performance at essentially constant solvent composition. The measured conversion is thus related to the rate of hydrogen donation from solvent of roughly a single composition. In contrast, the Equilibrium Test is performed at 399°C for 30 minutes at a 2 to 1 solvent to coal ratio. At these conditions, hydrogen donors can be substantially depleted. Thus performance is related to hydrogen donor... 

Autoclave Results - Solvent Activity Test. The initial microautoclave work was done with tetralin and methylnaphtha-lene, using Indiana V bituminous coal (Table I). Base line data is shown in Figure 4. All three tests, Kinetic, SRT, and Equilibrium, show an increase in coal conversion with an increase in the concentration of tetralin. The Equilibrium Test shows the highest coal conversion of approximately 86 wt% of the MAF coal (based on the solubility in the tetrahydrofuran) at the 50% tetralin concentration. The Kinetic Test shows lower coal conversion. The hydrogen transferred to the coal from the tetralin in the Equilibrium Test at the 50 wt% tetralin feed concentration is approximately 0.5 wt% of the MAF coal. In the Kinetic Test 50 wt% tetralin feed concentration results in a much smaller transfer at the short reaction time of 10 minutes. 

Microautoclave data was also obtained with Wilsonville Batch I solvent utilizing Indiana V coal. Batch I solvent was obtained from Wilsonville in mid-1977. Other batches of recycle solvent were received later. Batch I solvent had inspections most like the Allied 24CA Creosote Oil used for start-up at the Wilsonville Pilot Plant. Succeeding batches of solvent received by CCDC showed substantial differences, presumably due to equilibration at various operating conditions. As the Wilsonville solvent aged and became more coal derived, the solvent aromaticity decreased with an increase in such compounds as indan and related homologs. The decrease in aromaticity has also been verified by NMR. A later solvent (Batch III) also showed an increase in phenolic and a decrease in phenanthrene (anthracene) and hydrogenated phenanthrene (anthracene) type compounds. 

Figure 4. Microautoclave tests, Indiana V coal, Tetralin-methyl naphthalene mixtures (conversion vs. percent Tetralin content)...

Figure 5. Microautoclave tests, Indiana V Coal (conversion at 440°C vs. time). Batch I solvent (O), 8.7% hydrogen solvent 3/1 S/C (0), 8.9% hydrogen solvent 3/1 S/C ([J), 8.0% hydrogen solvent 3/1 S/C (A), 8.0% hydrogen...

MICROAUTOCLAVE DATA-LIGHT PHASE SRC ADD IT ION-INDIANA V COAL... 

Continuous Bench-Scale Experimentation With encouraging results obtained from microautoclave tests, experimentation emphasis moved to the bench-scale unit Here the concept of adding Light SRC to the recycle solvent on a continuous basis was tested Earlier work (j>) performed on short contact time coal liquefaction showed Indiana V coal to be out-of-solvent balance Also the operability of the continuous bench-scale SRT unit was highly dependent upon the quality of the solvent ... 

Table III shows the results of operating the SRT unit in the hydrogen donor mode (catalytically hydrogenated solvent) with and without the addition of Light SRC to the distillate solvent Batch I solvent was used in Run 9 A blend of Batch VI solvent and Light SRC, 70/30 weight ratio, were catalytically hydrogenated as the feed to Runs 1 and 3 The hydrogen donor capability of the solvents were measured by the Equilibrium microautoclave tests These bench-scale SRT results are rather extraordinary in respect to increased distillate yields and improvement in unit operability with addition of Light SRC In Table III the integrated yields refer to the combination of liquefaction, CSD, and catalytic hydrogenation of the solvent ...

Aspects of coal liquefaction have been much researched, particularly with the re-emeigence of interest caused by the oil crisis in the 1970 s. The type of reactors used in the studies has been various, ranging from small bomb type microautoclaves through larger autoclaves and bench-scale reactors to larger scale pilot or demonstration plants. The use of differently sized and designed high pressure equipment for liquefaction studies further complicates an already complex system and allows only limited comparison of results. 

Reaction of Hydrogenated Products with Sulphur. These experiments were conducted in a 10 cm capacity tube-tuype microautoclave (manufactured by Baskerville Scientific Ltd) fitted with a 0-10 bar Schaevitz pressure tranducer linked to a digital read-out. The microautoclave sat in its own elearical heater and its temperature was controlled by a thermocouple linked to a read-out. The pressure of H2S was monitored and once it became... 

Chemical test using sulphur as an hydrogen acceptor Sulphur will readily accept donatable hydrogen to produce H2S whose partial pressure will be proportional to the concentration of H-donors. This reaction provides a simple method for monitoring H-donors contents and initial experiments showed that only small amounts of sulphur and the hydrogen donor compound were needed for the reaction. The method was calibrated using 0.5 g of sulphur with various amounts of 9,10 dihydrophenanthrene (H2) which were reacted at 275 C in a 10 cm3 microautoclave. Plots of pressure vs. time (Figure 3) indicates that an equilibrium pressure was reached in 30 mins or less. 

Tests on the activity of LP-produced Fe-based nanopowders for liquefaction of a sub-bituminous coal under high (688 K, 1 h of reaction) and low (658 K, 0.25 h of reaction) severity conditions have been reported.38 The catalysts tested were Fe7C3 (92 m2 g 1 (BET), particle size = 17 nm (XRD))and Fe XS (42 m2 g 1 (BET), particle size = 14 nm (XRD).38 For comparison, a commercial superfine iron oxide catalyst (SFIO, supplied by Mach I, Inc.) whose major phase has been identified in one study as y-Fe20339 (surface area = 195 m2 g 1 (BET), particle diameter = 3 nm (XRD)) and in other study as the ferrihydrite40 was also evaluated under similar conditions. The coal liquefaction experiments were carried out in 50 cm3 horizontal microautoclave reactors loaded with 3 g of sub bituminous Black Thunder coal and 5 g of tetralin used as hydrogen donor. Catalyst loadings of 0.7% and 1.4% of as-received coal... 

Dr. Denis Doizi of CEA presented about the HIx Vapour Liquid Equilibrium (VLE) measurement. A collection of accurate thermodynamic data for the HIx section is critical for robust modelling of the S-I process. CEA has developed experimental techniques to obtain such data at the high temperatures and pressures expected in a full-scale plant. A tantalum microautoclave was used to collect data, with FTIR spectrometry used to analyse HI and H20 concentrations. UV-visible spectroscopy was used for... 

The high-pressure device is a microautoclave made of tantalum and located in a thermo-regulated oven as shown in Figure 2. It is a closed reactor with a constant volume of 140 cm3. The total expected pressure is about 80 bars for a temperature close to 280°C. Tantalum has been chosen as the reference material for the internal part of the reactor in order to avoid corrosion from the products under study. 

Figure 5. Layout of a microautoclave with the swinging capillary stirrer.

Catalyst screening tests were conducted in 40-mL microautoclave reactors. The liquefaction conditions were the following temperature, 425°C reaction pressure, 1000 psig H2 (pressure at room temperature) residence time, 1 hour and solvenVcoal, 2/1. The coal used was Illinois No. 6 hvBb from the Burning Star Mine, properties of the coal used are summarized in Table I. 

The vehicle used was tetrahydronaphthalene (tetralin). Rapid heat-up rates were obtained by immersing the microautoclave in a preheated fluidized sand bath at 425°C. The microautoclave reached reaction temperature in 1-2 minutes. Slow heat-up rates were obtained by immersing the microautolcave in the fluidized sand bath at room temperature and gradually heating the sand bath to reaction... 

Microautoclave — Illinois No. 6 Coal, Tetralln, Solvent/Coal = 2, 425"C, 1 hr. 

Micro bomb tubes are used for reactions in a homogeneous phase at pressures up to 15-20 atm. Microautoclaves fitted with a heating mantle and temperature control are also available for small quantities when placed in a shaker, these can be used also for reaction of heterogeneous phases. Reactions of a few milligrams of material can be carried out in thick-walled capillaries under high pressure. 

AC catalysts were compared with the C0M0/AI2O3 catalyst under identical conditions. The experiments were conducted in a microautoclave at 2.9 MPa of H2 between 573 and 653 K. Rate constants were determined for the network... 

A microautoclave MAS NMR rotor was developed enabling in situ monitoring of solid-liquid-gas reactions at high temperatures and pressures. It is used in a kinetic and mechanistic study of the reactions of cyclohexanol on zeolite. The NMR spectra show that dehydration of C-cyclohexanol that occurs with a proposed mechanism. ... 

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