Albert S. Hirschon

Ruthenium promoted hydrodenitrogenation catalysts

Abstract The promotion of a commercial CoMo hydrotreating catalyst with an active amine transalkylation catalyst, Ru 3 (CO) 12 , was investigated. The resulting catalyst, RuCoMo, exhibited enhanced HDN activity on quinoline and gave a 5-fold increase in selectivity to aromatic hydrocarbon products. Unlike bulk ruthenium, the ruthenium promoted catalyst was sulfur tolerant.

The effect of carbon additives on the mesophase induction period of Athabasca bitumen

Abstract The ability of solid carbonaceous material to retard the formation of coke during thermal cracking and hydrocracking of heavy hydrocarbons is well known. In this study, we used in-situ microscopy (hot-stage) to obtain additional mechanistic information on whether fine coke and fullerene soot particles retard the growth of mesophase during thermal cracking of Athabasca bitumen, thus reducing the possibility of fouling in preheaters and furnaces. The findings from this study could also have application in other non-catalytic thermal processes such as visbreaking and coking. In the absence of additives in the Athabasca bitumen feed, the formation of mesophase occurred after 61 and 67 min (measured from room temperature) at reaction temperatures of 450°C and 440°C, respectively. The addition of solid coke (ca. 5 wt.%) from a commercial delayed coking operation shortened the mesophase formation time to almost 45–50 min under similar conditions. The coke, having surface area of only 1.65 m 2 /g, resulted in enhanced bitumen fluidity and large-textured mesophase. These observations were rationalized based on the ability of delayed coker coke to release hydrocarbons into the bulk fluid during thermal cracking. Light hydrocarbons released from coke may have changed the solvating power of the liquid phase in bitumen and promoted phase separation, resulting in a shorter induction period. In contrast, adding small amounts of fine fullerene soot (ca. 1 and 5 wt.%) delayed the appearance of mesophase significantly under similar conditions. The ability of fullerene soot to physically absorb the mesophase precursors into its pore structure led to an increase in the apparent viscosity of the bulk phase, which is known to reduce mesophase size and prolong the induction period. Consistent with this, the induction period was prolonged an additional 10 min when the soot surface area was increased from 152 to 208 m 2 /g. The increase in induction period is significant with respect to reaction times and suggests that these fullerene soot materials could be effective in allowing for increased severity and liquid products yield from visbreaking, with less likelihood of fouling in the preheater tubes and furnace walls.

Hydrothermal treatment and the oxygen functionalities in Wyodak coal

The effects of hydrothermal treatment (liquid water) at 350 °C on Argonne-supplied Wyodak coal previously ‘dried’ at 60 °C under 1 torr for 18 h were studied. Control experiments were conducted in the absence of added water, and with n-undecane replacing water. All runs were conducted in batch reactors with quartz liners for periods of 30 min or 5 h with added N2 (500 psi cold), and product workups and all manipulations were conducted in an N2 glove bag. A tar representing 5–7% of the starting coal was deposited on the quartz walls solely for hydrothermal conditions. In all cases the coal lost oxygen, the O-losses being in the order: undecane < no added water (30 min) = added water (30 min) = no added water (5 h) < added water (5 h). Thermal gravimetric and field ionization mass spectrometer (f.i.m.s.) analyses (ambient to 500 °C at 2.5 °C min−1) showed little difference between the experiments with undecane and those with no added water. By contrast, hydrothermal treatment yielded a volatiles fraction that was at the same time more volatile and had a greater weight average molecular weight. Phenol, catechol, and their C1-, C2-, and C3-derivatives were the two most prominent families in the f.i.m.s.-volatiles spectra, and the f.i.m.s. responses showed that under added water conditions the catechols response was increased. With undecane in place of water, the precursors to the f.i.m.s.-volatile arenols engaged primarily in regressive chemistry. The exhaustive (5 h) hydrothermal treatment resulted in virtual elimination of both phenol and catechol signals, demonstrating extensive hydrolysis of the coal structure. The results are consistent with a scheme in which water promotes the production of the tar, removing it from the coal matrix. The organic medium, on the other hand, suppresses the diffusion of thermally generated fragments, and they become irreversibly reincorporated. The O-losses are due primarily to CO2- and H2O-evolution. The data suggest that the latter is largely due specifically to catechol dehydroxylation.

Chemistry of hydrogen sulphide under coal liquefaction conditions: 1. Modelling hydrogen transfer catalysis

Abstract The work reported here represents initial attempts to develop a complete kinetic and mechanistic understanding of the reaction chemistry of H 2 S under coal liquefaction conditions, using both model systems and coal. Hydrogen sulphide was found to promote/catalyse the transfer of hydrogen from tetralin to 2-hydroxyquinoline (2-HOQ). The presence of H 2 S can increase the rate of hydrogen transfer from tetralin to 2-HOQ by a factor of 10 compared with the same reaction run in the absence of H 2 S. The energy of activation for hydrogen transfer was found to decrease by ≈5 kcal mol −1 in the presence of H 2 S. The presence of H 2 S was also found to promote loss of oxygen from 2-HOQ to form small amounts of quinoline. No evidence of CC or CN bond cleavage in 2-HOQ was noted under any of the reaction conditions studied. These results suggest that the presence of H 2 S reduces the temperatures necessary to promote effective hydrogen transfer from tetralin by 50–75 °C. Moreover, they imply that similar effects occur in H 2 S-promoted coal liquefaction.

Highly dispersed coal liquefaction catalysts

Abstract Iron and molybdenum complexes were studied as precursors to high dispersion catalysts for coal liquefaction. The precursors were either organometallic complexes or water-soluble salts and were impregnated into coals of various ranks. The molybdenum catalysts were found to be very effective for conversion of an Illinois no. 6 bituminous coal whereas the iron catalysts were not. In contrast, the iron catalysts were found to be very effective for lignite conversions. A H-donor and a non-donor conversion system were compared, using tetralin and n-hexadecane, respectively. In each case the organometallic precursor gave greater yields of toluene-soluble material, with differences being most dramatic in the hexadecane system. The yields using the organometallic molybdenum presursors in hexadecane were found to be almost as great as those in the tetralin system, indicating that good catalyst precursors do not require donor solvents. The impregnation techniques were evaluated by comparing conversion yields and analysing the products using field ionization mass spectroscopy and FT-i.r.

Extractions and reactions of coals below 100 °C: 4. Oxidations of Illinois No. 6 coal☆

Abstract This paper summarizes efforts to increase the solubilities of coal fractions, with minimum loss of carbon, by oxidations with aqueous NaOCl, oxygen, and nitric acid, at or below 60 °C. The principal products were ‘black acids’, insoluble in water but sparingly soluble in dilute aqueous base; small proportions of colourless, water-soluble acids were also obtained. The best yields of black acids (60–80% on carbon and the lowest losses of carbon (10 to 20%) varied little with the oxidizing agents used. The H C ratios of black acids obtained with nitric acid (~0.6) were lower than in the starting materials (0.73), indicating loss of more aliphatic than aromatic material. Oxidations with oxygen and NaOCl at pH 13 indicate that somewhat more aromatic than aliphatic carbon was lost during oxidation. The small residues of undissolved coal had H C ratios ∼0.9. Some of the black acids were fractionated by size-exclusion and high performance liquid chromatography; the methods appear to have considerable potential for investigating coal structure. Fractional precipitation of black acids from water with hydrochloric acid over the pH range 6-4 gave products of only a small range of average compositions. An effort to find diaryl ketone groups in black acids by oxidation with m -chloroperbenzoic acid, and thus evidence of single methylene groups between groups in coal, found no conclusive evidence of such groups, but the method is insensitive.

Catalytic hydrodenitrogenation of an SRC-II coal liquid: Effect of hydrogen sulphide

Abstract The addition of hydrogen sulphide to an SRC-II coal liquid under hydrodenitrogenation conditions resulted in a significant decrease in the nitrogen content of the product. The reaction was run in a batch reactor for 1 h at 400 °C with a presulphided Harshaw CoMo catalyst and at 1200psig (8.39 MPa) initial H 2 S H 2 pressure.

Chemistry of hydrogen sulphide under coal liquefaction conditions: 2. Synergistic effects of H2S and the mixed solvent system tetralin and tetrahydroquinoline on liquefaction of a moderately reactive coal

A preliminary study was undertaken to evaluate the effects of mixed solvents and added H2S on the overall conversions of a moderately reactive coal (Wyodak-2) as defined by tetrahydrofuran solubility. Conversion efficiencies were measured as a function of time and of H2S concentration in the H2S-tetrahydroquinoline (THQ) solvent system. The specific solvent systems studied included tetralin and mixtures of tetralin and THQ, with and without H2S. In all cases, coal conversion was enhanced by the presence of H2S, THQ or both, relative to the use of tetralin alone. Conversion as a function of THQ concentration was also determined. The relative abilities of the various combinations to effect conversion were found to be as follows: tetralin < 5 wt% THQ-tetralin < 3 wt% H2S-tetralin < 10 wt% THQ-tetralin = 20 wt% THQ-tetralin < 3 wt% H2S-20 wt% THQ-tetralin. From these results, it is concluded that both H2S and THQ operate synergistically to provide enhanced yields of high-quality coal liquids. The relations between conversion, H2S concentration and nitrogen incorporation are discussed.

Extractions and reactions of coals below 100 °C: 2. Reactions of the toluene-insoluble, pyridine-soluble fraction of Illinois No. 6 coal

The toluene-insoluble, pyridine-soluble (TIPS) fractions of an Illinois No. 6 coal were investigated as a model for the insoluble portion of coal. Various TIPS fractions had number-average molecular weights (Mn) in pyridine of 9080 to 1380. These fractions were treated with a variety of reagents known to cleave ester and ether bonds. The abilities of these reagents were measured by decrease in Mn of the TIPS products. The order was found to be: ZnCl2> LiI · H2O > pyridine · HI > benzylamine > alcoholic KOH > toluene sulphonic acid. Ester groups were determined from saponification equivalents and the effects of alcoholic KOH. Evidence for ethers came from effects of amines, HI and sodium on the Mn. HI appears to cleave more bonds and more phenyl alkyl and benzyl ether than dialkyl ether bonds.

Extractions and reactions of coals below 100 °C: 3. Comparison of extraction products of Illinois No. 6 coal☆

Abstract Exhaustive extractions of Illinois No. 6 coal at 100 °C show that pyridine extracts about 16% without chemical reaction; benzylamine and ethylenediamine extract ~45%. Reactions of coal extracts and extracted coals with pyridine HI and ZnCl 2 in pyridine and with alcoholic KOH correspond to cleavage of ester groups by benzylamine and KOH and cleavage of both ethers and esters by HI and ZnCl 2 at or below 50 °C, and by the amines in several days at 100 °C. The amine-extracted coals are highly swollen by these solvents and are apparently held together mostly by CC bonds with dangling oxygen and nitrogen functions. Reactions of all the extracts and extracted coals with alcoholic KOH indicate that their average contents of phenol + ester groups are fairly constant. The toluene-insoluble pyridine-soluble (TIPS) portion of the pyridine extract appears to be a good model for other fractions. We estimate that it averages 0.8 ester, 1.2 labile ether, and three phenol groups per 1090 molecular weight or per 70C atoms. These groups account for 64% of the oxygen in the fraction. However, this fraction can be separated into fractions of different O and H/C contents and different molecular weights. Such heterogeneity should be characteristic of all fractions.