Hydrogenation solvents

Fig. 24. Molecular structure of [ N3P3(NC6Hn)6 2(thf)4Li12] (hydrogens, solvent molecule, and two cyclohexyl groups are omitted for clarity).

Figure 6. Influence of digestion time on the extraction yield and yield of filter cake. Digestion Annesley coal/hydrogenated solvent prepared at 430°C (— —), yield of filter cake (------------------), extraction yield.

Table III shows that hydrogenated and unhydrogenated SRC recycle solvents were equally effective for the conversion of a western subbituminous coal at low reaction severity. At higher severity but at times shorter than 10 minutes, significantly higher conversions were achieved only with the hydrogenated solvents which could donate more hydrogen.

Four variables were studied in the part of the experimental program which examined the first step of the proposed two-step process. The variables were reaction temperature (413-454 C), solvent to coal ratio (2 1 and 3 1), residence time (0-5 minutes), and pressure (300-1800 psi nitrogen). Four experiments were done to simulate the second step, in which hydrogenated solvent and molecular hydrogen would be used to lower the sulfur content of the product. These experiments were done at 441 C for 2 minutes, with and without molecular hydrogen and recycle solvent containing 25 weight percent Tetralin. 

A blend of Wilsonville recycle solvent (75 weight percent) and 1,2,3,4-tetrahydronaphthalene (25 weight percent) was prepared for use as the solvent in experiments simulating the second process step, which would use hydrogenated solvent. Analyses and distillation data for this solvent are also given in Table 2. Tetralin boils below 232 C and was collected in the light oil distillation fraction during product workup. 

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...

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 ...

Addition of dry catalyst to 98% formic acid used as a hydrogenation solvent can be extremely hazardous, because hydrogen is released by decomposition of the acid. Addition of acid to the water-wetted catalyst is safer. 

Due to the possiole influence of sodium hydroxide on the reaction oehaviour, a special care must De taken for catalyst washing (ref.6). When the reaction takes place in an alcohol the metallic powder is washed three times with distilled water, three times with absolute methanol and three times with the alcohol. If cyclohexane is the hydrogenation solvent, the operation is followed by an additional step in toluene. 

The selective hydrogenation of the olefinic double bond in the acetylated carbohydrate C-nitroolefins, using palladium black as catalyst, depends to a marked degree on the solvent employed. In absolute ethanol a sharp decrease in the rate of hydrogen absorption usually occurs when the double bond has been saturated. This decrease in rate is not sharply defined in 95 percent ethanol and is not detectable when absolute ethyl acetate is employed as the hydrogenation solvent. 

Comparison of the low hydrogen solvent (92-03-035) with the heptane soluble fraction from a SCT liquefaction which employed the low hydrogen solvent by vpc indicates that the heptane solubles closely resemble the starting solvent. 

The reaction conditions and product analyses of the hexane solubles for SCT liquefaction of Belle Ayr coal in high and low hydrogen solvents are shown in Tables 3 and 4 respectively. 

Examination of gas samples taken prior to the injection of coal from our SCT runs with Monterey coal and with low hydrogen solvent indicate that as the severity of the conditions to which the solvent is exposed increases, the amount of paraffins and olefins (C - C5) increases (Figure 6). A gas make of 3.6% was formed in the run of highest severity. 

In thermal coal solvation, a reaction occurs between dissolved hydrogen (or hydrogenated solvent) and the fragmented coal molecules to produce a host of products. 

Mercury(II) salts form addition compounds with olefins, particularly in the presence of active-hydrogen solvents such as alcohols. Although a... 

Generally, solvents exert a greater effect upon competitive reactions than upon the individual reaction rates when corrected for the solubility of hydrogen.Solvents which are strongly nucleophilic, such as amines, compete for active sites, and benzene slows the hydrogenation of alkenes, particularly on Pd. -2 ... 

Fig. 2 Schematic picture of a set of contrast variation experiments (A) hydrogenous hydrophobe and head group, deuterated solvent (drop contrast) (B) deuterated hydrophobe hydrogenous head group and deuterated solvent, (shell contrast) and (C) deuterated hydrophobe and hydrogenous head group and hydrogenous solvent (core contrast).

Hydrogenation solvent. Trifluoroacetic acid appears to be the best solvent for the platinum-catalyzed hydrogenation of ketones. The rate in this solvent is approximately three times the rate in acetic acid. A relatively high concentration of the ketone should be used, since the reactions are slow in dilute solution. The alcohol is frequently obtained as the ether. 

Hydrogenation solvent. The acid is preferred as solvent for hydrogenation (Pt or Rh) of pterines, since complete and selective hydrogenation of the pyrazine ring of pterine, its N-methylated derivative, and of folic acid is effected in short time. ... 

The direct liquefaction of coal is a process that involves the interaction between coal, hydrogen, solvent, and catalysts. 

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