Pasting oil

Gustin, DM, Rodvold KA, Sosman JA et al. 2004. Single-does pharmakinetic study of lycopene delivered in a well-defined food-based lycopene delivery system (tomato pasted-oil mixture) in healthy adult male subjects. Cancer Epidemiol Biomarkers Prev 13(5) 850-860. 

Many studies on direct liquefaction of coal have been carried out since the 1910 s, and the effects of kinds of coal, pasting oil and catalyst, moisture, ash, temperature, hydrogen pressure, stirring and heating-up rate of paste on coal conversion, asphaltene and oil yields have been also investigated by many workers. However, few kinetic studies on their effects to reaction rate have been reported. 

In this paper the effects of kinds of coal, pasting oil, catalyst and reaction temperature on coal liquefaction are illustrated, and a few kinetic models for catalytic liquefaction of five coals carried out in an autoclave reactor are proposed. 

The reaction rate, oil yield are affected by kinds of pasting oil and ratio of coal to pasting oil. 

Paste (oil paste) is an ointment containing more than 10% pulverized constituents. 

When the reaction was complete (claimed to be as short a time as one-half hour in some cases), the reaction mixture was removed from the autoclave, and solids were removed by filtering. The liquid product was then distilled. A yield of about 44% of monophenols based on the lignin was obtained with an additional 20-24% of heavy oils, suitable for use as recycling pasting oils. The rest of the lignin was lost as light oil, gas, and water. The monophenol fraction was composed of phenol, 0-cresol, p-cresol, p-ethylphenol and />-propylphenol. 

The apparent yields of monophenol ranged from 15% at 370°C. to 44% at 430°C. Neither the phenol nor the green lignin tar used for pasting oil could be completely recovered, and losses of 20-30% of the pasting oil were noted. Large, pitchy, nondistillable residues were obtained. In addition to the monophenols previously determined by the Noguchi Institute, we confirmed the presence of 0-ethylphenol, 0-w-propyl-phenol, 2,4-xylenol and 2,6-xylenol. 

After learning that we could achieve the same results as the Japanese by using stabilized lignin tar as the pasting oil, we made a number of miscellaneous hydrogenation runs. The results of some of these are shown in Table II. 

To eliminate the high pressure resulting from the excessive water, we studied the use of dried SWL solids in several experiments. It was never possible completely to recover pasting oil when the dried solids were used. At 380°C. the paste oil was nearly recovered, but the monophenol yield was low. At 428°C., the paste oil recovery was lower, and the monophenol yield was higher. In one experiment the dried solids were extracted with liquid ammonia so that carbohydrate material would be removed from the calcium lignin sulfonate. Approximately 10% of the solids were removed... 

The possible use of pasting oils other than stabilized lignin tar was studied, and we learned a considerable amount about the stability of some of the monophenol products of the hydrogenation. We concluded that meta and para isomers are more stable than ortho isomers and should be the favored configuration as the result of repeated hydrogenations. The results of some of these experiments are shown in Table III. 

Neutral oils, obtained by extracting the monophenol cut with caustic, were tried as paste oil. These gave monophenols and must have contained phenyl ethers which cleaved upon hydrogenation. 

As the result of many experiments, we concluded that a 55% concentrate of desugared, spent liquor was the best lignin starting material, based on cheapness and paste oil recovery. We also concluded that light oils (containing many hydrocarbons, etc. such as cyclohexane and benzene),... 

A paste oil of the estimated composition was made up and used in hydrogenation. The total salable monophenols (b.p., 180°-205°C.) yield from this was found to be 8.5%, and a stabilized lignin tar yield from the second hydrogenator was 19% of the net organic of the lignin. In addition to the yield data, we fractionally distilled the combined monophenol cuts from the continuous runs. The m->p-cresol peak from the gas chromatograph was analyzed by IR spectroscopy and found to be 45% w-cresol and 55% p-cresol, which meant that no pure p-cresol could be obtained by fractional crystallization of the meta, para mixture. From the fractional distillation we found we could obtain most of the monophenols indicated in the gas chromatographic analysis. 

When one-step desulfonated lignin and low pressure were used with a paste oil of 13% phenol and 87% lignin tar, the meta-para ratio was only 12 88. 

As the result of these experiments, using 12-15% phenol (this amount could usually be completely recovered or else the makeup was small) in the pasting oil was adopted as a standard procedure. One experiment using sodium phenoxide as the strongest ortho-para directing substance, was not successful owing to the condensation of the phenoxide with lignin. 

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