Pyridine solubles conversion

Working co-operatively with others, we have found some indication that certain alilphatic linkages between aromatic nucleii are involved in the rapid dissolution of coal. The absolute aliphatic hydrogen content as determined by P. Solomon using FTIR (22) shows a very good linear relationship with conversion of coal in 3 minutes to pyridine soluble materials (Figure 14a). 

Table I compares the conditions and results of this operation to those for conventional SRC for Illinois 6 coal. At the short residence time, the coal conversion determined by pyridine solubility is 89% compared to 95% at conventional SRC conditions. The hydrogen consumption and production of light gases are reduced significantly at short residence time, while the SRC yield is increased.

We have discovered that ZnC, in combination with methanol, constitutes an active liquid-phase catalytic medium for conversion of coal to pyridine-soluble material. There are several possible explanations for this effect improved contact between coal and melt higher activity of the ZnCl2 in the methanol medium methylation of cleaved bonds resulting in reduced char formation and extraction of the reaction products leaving the coal more accessible. 

Results showing the effectiveness of the A1- and A2-dialins in coal liquefaction relative to control solvents, naphthalene, Decalin, and fetralin, are presented in Tables 3.1 and 3.2. In both these tables, each row provides the conversion of the coal sample to each of hexane-, benzene-, and pyridine-solubles (plus gases) by the indicated solvent. Table 3.1 contains data derived at a temperature of 400 C and a reaction time of 0.5 hr. Among the control solvents, it can be seen that the naphthalene... 

Primary Conversions and Influence of Mobile Phase Yields for the various H-donor and non-donor solvent extractions of Linby coal at 400% are summarised in Table III the conversions for the THF-extracted coal include the extracted material. Surprisingly, pre-extraction with THF significantly increases primary conversions in the polynuclear aromatic compounds (PACs) investigated. These findings appear to be contrary to those of other liquefaction (16) and pyrolysis (17) studies where prior removal of chloroform-extractable material significantly reduced conversions. However, Rincon and Cruz (18) have reported recently that pre-swelling coals in THF increases conversions for both anthracene oil and tetralin. The fact that Point of Ayr (87% dmmf C) coal yielded over 80% pyridine-solubles in pyrene (C.E. Snape, unpublished data) without pre-extraction is consistent with the earlier results of Qarke et al (19) for anthracene oil extraction where UK coals... 

Conversions to pyridine-solubles for non-THF-extracted Linby coal were much greater with naphthalene than with phenanthrene and pyrene (Table m, pre-soaking at 250% has little effect on conversions) and, even after THF extraction, naphthalene conversions are comparable to those of pyrene. 

Although Neavel obtained high yields of pyridine-solubles with naphthalene at short contact times for some US bituminous coals (201. conversions were much lower after longer extraction times. This trend is not evident for Linby coal... 

Figure 1. Conversion of THF-extracted Linby coal with naphthalene at 400 C. Pyridine-solubles and THF-solubles.

Further evidence of the importance of the physical nature of the solvent is found in the work of Belssing and Ross (6) who correlated the coal conversion (pyridine solubles) with the Hildebrand solubility parameter, 6, which they defined as... 

Summary of Experiments. Fifteen coal liquefaction experiments were done using two coals and two solvents supplied by Mobil Research and Development Corporation. Each coal-solvent combination was tried at conditions designed to give conversions to pyridine solubles of about 65 and 80 percent of MAF coal. 

TABLE III. RELATIONSHIP BETWEEN REACTION TIME, TEMPERATURE, REACTION SEVERITY AND CONVERSION OF WYODAK COAL TO PYRIDINE SOLUBLES... 

Reaction Time, min Temp, °F (°C) % MAF Coal Conversion to Pyridine Solubles Reaction Severity. Rg(x 10-10)... 

Product Workup Procedures, A sample of the products was continuously extracted with THF and then with pyridine. Pyridine insolubles were analyzed for ash and conversions of MAF coal to pyridine solubles were calculated on the basis of the ash analyses and the mass recoveries. A mass recovery balance was calculated for each experiment. The mass recoveries averaged 97.8 percent. The mass and ash based conversions diverged by an average of only 2.7 percent. 

MAF Coal Conversions to Pyridine Solubles. MAF coal conversions, based on ash analyses, are shown for each coal-solvent combination in Figure 3. Subbituminous coal is converted more slowly, resulting in lower conversions at identical reaction severities than bituminous coal. Maximum conversions are higher with bituminous coal, approaching 90 percent on an MAF basis for the Monterey coal compared to about 75 percent for Wyodak coal. 

Figure 3. Comparison of conversion of MAF Wyodak (—035 solvent (A/ —0/9 solvent (0)) and Monterey (—035 solvent (O) —019 solvent ( Z )) coals to pyridine solubles (based on ash analysis)...

MAF conversions to pyridine solubles from short contact time coal liquefaction are dependent on the coal type, solvent source, and reaction severity. As reaction severity increases conversions approach a maximum value with a hydrogen-enriched solvent but go through a maximum and decline with a hydrogen-depleted... 

Figure 1 shows the relationship between conversion, defined as gas + pyridine soluble liquids, and Rs derived at two different maximum temperatures. It can be seen that the conversions obtained at similar severities are the same (within experimental error). This is true even though all of these data involved rather extreme time-temperature fluctuations. Within limits a certain reaction severity can be obtained either at lower temperature (800°F) for longer time (6 min.) or at higher temperature for shorter time. 

Conversion is defined as the sum of the products that distill below 400°C and the pyridine-soluble fraction of the 400+ C material. Thus in the example given, 91 — 64 = 27% represents water and volatile products, a minor 400 C fraction, and manipulation losses. The balance of 9% is ash and insoluble material. 

For these coals, addition of pyrite enhanced oil yields v conversion of asphaltenes and preasphaltenes, but did not affect the overall conversion of the coal to pyridine-solubles. Addition of pyrite to bituminous coals deficient in pyritic sulfur or iron increased oil yields to levels comparable to coals with naturally high concentrations of pyrite. For Ayrshire coal (Indiana VI) with 1.1% pyritic sulfur, the oil yield was 31%. Addition of 2.7% pyrite (based on coal) increased the oil yield to 50%. 

Addition of 5.2% pyrite resulted in an increase in oil yield to 54% and a corresponding increase in conversion to pyridine solubles from 91% (without added pyrite) to 96%. 

For a Texas (Big Brown) lignite, SRC-II processing was possible without catalyst addition and resulted in an oil yield of 50% and a conversion (pyridine solubles) of 95.9%. When 2.9% pyrite was added, the oil yield increased to 61% and the... 

The above forced flow procedure was employed to determine trace element content in six additional pyridine soluble SRC s. Each SRC differs from another in either raw coal source, conversion severity (i.e. pressure-temperature), added Na2C03 content or method of residue removal. Table III outlines the various processing parameters and the assigned run number. The measured elemental concentrations are listed in Table IV. 

When coal is heated in a slurrying vehicle, it is liquefied at 400°C-500°C (750°F-930°F). Though the reaction mechanism involving conversion of coal to oil is very complex, it appears that the interaction of coal with solvent at the initial stage of the reactions plays the vital role to determine the sequential conversion of coal substances—first to a pyridine-soluble solid and thereafter to benzene-soluble liquid hydrocarbons and low-boiling products. Thus the isolation and identification of the products of coal-solvent interactions to yield pyridine-soluble matter may provide information regarding the suitability of the coal for liquefaction. 

The conversion of a carbonyl compound by ammonium polysulphide solution into an amide with the same number of carbon atoms is known as the Willgerodt reaction. The procedure has been improved by the addition of about 40 per cent, of dioxan or of pyridine to increase the mutual solubility of the ketone and aqueous ammonium polysulphide the requisite temperature is lowered to about and the yield is generally better. 

Chain-Growth Associative Thickeners. Preparation of hydrophobically modified, water-soluble polymer in aqueous media by a chain-growth mechanism presents a unique challenge in that the hydrophobically modified monomers are surface active and form micelles (50). Although the initiation and propagation occurs primarily in the aqueous phase, when the propagating radical enters the micelle the hydrophobically modified monomers then polymerize in blocks. In addition, the hydrophobically modified monomer possesses a different reactivity ratio (42) than the unmodified monomer, and the composition of the polymer chain therefore varies considerably with conversion (57). The most extensively studied monomer of this class has been acrylamide, but there have been others such as the modification of PVAlc. Pyridine (58) was one of the first chain-growth polymers to be hydrophobically modified. This modification is a post-polymerization alkylation reaction and produces a random distribution of hydrophobic units. 

Dipyridiue-chromium(VI) oxide2 was introduced as an oxidant for the conversion of acid-sensitive alcohols to carbonyl compounds by Poos, Arth, Beyler, and Sarett.3 The complex, dispersed in pyridine, smoothly converts secondary alcohols to ketones, but oxidations of primary alcohols to aldehydes are capricious.4 In 1968, Collins, Hess, and Frank found that anhydrous dipyridine-chromium(VI) oxide is moderately soluble in chlorinated hydrocarbons and chose dichloro-methane as the solvent.5 By this modification, primary and secondary alcohols were oxidized to aldehydes and ketones in yields of 87-98%. Subsequently Dauben, Lorber, and Fullerton showed that dichloro-methane solutions of the complex are also useful for accomplishing allylic oxidations.6... 

The product workup consisted of continuously extracting the filter cake with tetrahydrofuran (THF) and combining the THF and filtrate to make up a sample for distillation. In some experiments the THF extracted filter cake was extracted with pyridine and the pyridine extract was included in the liquid products. Extraction with pyridine increased coal conversion to soluble products by an average of 1.6 weight percent. The hot filtrate-THF-pyridine extract was distilled. Distillation cuts were made to give the following fractions, THF (b.p. <100 C), light oil (b.p. 100-232 C), solvent (b.p. 232-482), and SRC (distillation residue, b.p. >482 C). 

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