Christine W. Curtis

Thermal and catalytic coprocessing of waste tires with coal

Thermal and catalytic coprocessing of waste tires and coal was performed using waste tires from two sources and coals of three different ranks. Bituminous coals yielded higher conversions than either subbituminous coal or lignite when coprocessed with waste tire. In this study waste tires from tire buffing processes were used. One of these materials provided by Rouse Rubber represented the typical composition of most automotive tires while the other material supplied by Uniroyal contained a substantial amount of mineral fillers because the material obtained from buffing the white lettering on the sidewall of the tire. Each of these waste tires when used as a solvent in coprocessing had different solvent qualities; the Rouse waste tire was typically a much better solvent for coal than Uniroyal waste tire. Catalytic coprocessing of waste tires with coal using slurry phase hydrogenation catalysts increased total and coal conversions compared to thermal reactions. Addition of carbon black to the coprocessing system had minimal effect on the conversion or product distributions, while the addition of the heat-treated residue from the liquefied waste tires resulted in enhanced conversion and hexane solubles production from coprocessing systems. The mineral-rich Uniroyal residue was more active than the carbon black-rich Rouse residue. Combining the residues with slurry phase hydrogenation catalysts enhanced their activity even further.

Thermal and catalytic coprocessing of Illinois No. 6. coal with model and commingled waste plastics

Abstract Coprocessing of waste plastics with coal was investigated at reaction conditions typical of direct liquefaction using slurry phase Mo and Fe hydrogenation catalysts. Reactions were performed with individual model polymers including polyisoprene, polystyrene, and high and low density polyethylene (HDPE, LDPE), and with coal alone in the presence and absence of a hydrogen donor solvent and catalysts at 400 °C and of an initial H 2 pressure of 5.6 MPa. Polyisoprene and polystyrene liquefied readily at these conditions; however, neither HDPE nor LDPE liquefied much with these catalysts or conditions. The conversion to THF solubles and product distributions from coprocessing reactions with coal and each polymer performed at the same reaction conditions were compared to those obtained with individual polymers. The coprocessing reactions with polyisoprene and polystyrene yielded thermal and catalytic conversions in the range of 62.3 to 95.5% while the coprocessing reactions with HDPE or LDPE yielded low conversion in the range of 20.2 to 43.2%. Catalytic reactions using carbon black, minerals, and fluid catalytic cracking catalysts were performed with HDPE and LDPE to evaluate their effect on conversion. After pretreatment, the fluid catalytic cracking catalysts showed activity for converting LDPE at 440 °C with an initial H 2 pressure of 5.6 MPa. Subsequent coprocessing reactions of LDPE and coal and commingled plastics and coal were performed with four fluid catalytic cracking catalysts and a zeolite HZSM-5. HZSM-5 was the most effective catalyst for converting both coprocessing systems although more gaseous products were produced than with the fluid catalytic cracking catalysts. The coprocessing reactions with commingled plastics, which consisted primarily of HDPE with some polypropylene, and coal yielded less conversion and less hexane-soluble materials than the LDPE coprocessing system.

Effects of solvent composition on coprocessing coal with petroleum residua

Abstract The effect of solvent composition on coprocessing of coal and petroleum solvents is examined under a variety of reaction conditions. The effects of solvent modification procedures on enhancing methylene chloride/methanol (MeCl/MeOH) soluble coal conversion and pentane soluble oil production are studied. Solvent modification procedures performed prior to coprocessing reactions include pentane deasphalting, catalytic hydrotreatment, H-donor addition, and blending of coal-derived liquids with petroleum solvents. Oil production and coal conversion were variously affected by the different solvent modifications. Prior hydrotreatment of petroleum solvents generally enhanced coal conversion, as did H-donor addition. The presence of a hydrotreating catalyst exerted a leveling effect on the effects of solvent modification. Blending of coal liquids and petroleum solvents resulted in complex and not readily predictable interaction. Solvents yielding the highest MeCl/MeOH soluble coal conversion were not generally the optimal solvents for pentane soluble oil production.

Pyrite-catalysed coal liquefaction using quinoline/tetrahydroquinoline as an H-donor system

Abstract Pyrite catalyses the hydrogenation of the N-containing ring in quinoline (Q) to form the active H-donor, 1,2,3,4-tetrahydroquinoline, (THQ). THQ is shown to dissolve coal readily at 325 °C, a temperature lower than that commonly used in most liquefaction processes. Pyrite is effective for maintaining the H-donor capacity of the solvent by hydrogenating the Q formed after H-donation, thereby providing the high THQ/Q required for sustained operation. Qualitative observations suggest that some source of hydrogen, either molecular or donor, must be present to prevent retrogressive reactions of coal fragments.

Coal solvolysis in a series of model compound systems

Abstract A series of 23 model donor solvents was used to rank their efficacy for the dissolution of Western Kentucky No. 9 14 coal. The transfer of hydrogen from the solvent to the coal fragments, as measured by coal conversion, was examined at three levels of available hydrogen. The hydrogen donors are ranked according to their ability to convert coal to THF-solubles. Aromatic analogs of the model donors showed little ability to convert coal to THF-solubles. Factors which influence hydrogen donation include the presence of heteroatoms or substituents both internal and external to the aromatic or hydroaromatic rings, the degree of hydrogenation, the aromaticity or non-aromaticity of the hydroaromatics, and the presence of five-membered rings. A relation between heats of formation and hydrogen donor ability is shown for hydroaromatics within two ring or three ring homologous series. A model hydrogen acceptor, benzophenone, is also used to rank model donors. No correlation exists in the ranking of hydrogen donors by the model acceptor used in this work and in other experimental studies and that obtained by conversion of Western Kentucky coal at typical liquefaction conditions.

ADSORPTION OF ASPHALT FUNCTIONALITIES AND OXIDIZED ASPHALTS ON AGGREGATE SURFACES

ABSTRACT The adsorption of asphalt functionalities and asphalt oxidized to different degrees on real and model aggregates has been investigated. The functionalities used were: nitrogen-base, phenolic, carboxylic acid, ester, ketone, sulfoxide, and polynuclear aromatic. Adsorption isotherms of these functionalities on porous silica showed different affinity rankings dependent upon concentration. The competitive affinity ranking of the asphalt functionalities on dried silica was obtained as phenylsulfoxide > qulnoline > phenol > benzoic acid > benzophenone > benzylbenzoate > pyrene. The sensitivity to moist silica surface of the four most strongly adsorbed compounds was: qulnoline > benzoic acid > phenol > phenylsulfoxide. Asphalts oxidized to different degrees were adsorbed on different aggregates. On silica and alumina, the oxidized asphalts with viscosities of 32,000 and 126,000 poise were adsorbed less than AC-20. On limestone and sandstone, the adsorption of AC-20 and oxidized asphalts was concentratio...

Contribution of transferable hydrogen to coal conversion

Abstract The contribution of transferable hydrogen in coal-derived solvents to coal conversion was investigated in a two-step process. Initially, the amount of transferable hydrogen in the coal-derived solvents was analysed by spectroscopic methods and by catalytic dehydrogenation. The spectroscopic methods included carbon magnetic resonance, proton magnetic resonance and a combination of the two. Three of the methods gave nearly equivalent quantities for the amount of transferable hydrogen present in the complex coal-derived liquids. Coal conversion determined in each of the coal-derived solvents was correlated to the amount of transferable hydrogen present. The contribution of transferable hydrogen is a significant factor in coal dissolution and the presence of saturates and hexane-insoluble compounds in these solvents may have a detrimental effect on coal dissolution.

Spectroscopic investigations of solvent-refined coal fractions

Abstract The chemical characteristics of Amax solvent-refined coal are investigated on a molecular size and component basis. Gel permeation chromatography (g.p.c.) is used to characterize the tetrahydrofuran-soluble portion of the SRC and to obtain the molecular size distributions, and is also used as a preanalysis step, in which fractions are obtained according to elution time. The THF-soluble portion of the SRC has elution times comparable to asphaltene plus oil. The resultant g.p.c. eluent is divided into six fractions, three of which have molecular sizes and elution times comparable to asphaltene alone, two to oil, and one to asphaltene plus oil. These observations are confirmed by chemical ionization and electron impact mass spectrometry. Various analytical techniques are used to establish further the composition of the fractions, including: infrared spectrometry, elemental analysis, flourescence excitation and emission spectrometry, high-pressure liquid chromatography and gas chromatography.

Catalytic coprocessing of LDPE with coal and petroleum resid using different catalysts

Abstract Catalytic coprocessing of low density polyethylene (LDPE) with coal and heavy petroleum resid was investigated using four different catalysts that included both hydrotreating and hydrocracking catalysts. Reaction systems that were evaluated included LDPE alone; LDPE with coal; and LDPE, coal, and resid. The catalysts used were NiMo/Al2O3, a hydrotreating catalyst with some hydrocracking activity, and the hydrocracking catalysts Zeolyst 753, NiMo/zeolite, and HZSM-5. These catalysts were reacted individually or in combinations of 10 wt.% of each hydrocracking catalyst in NiMo/Al2O3. The catalytic reactions were performed at two temperatures, 400 and 430°C, using 1 wt.% of each catalyst or a combination of catalysts on a total feed basis. The effects of the different catalysts on the reaction products were measured in terms of solvent fractionation and total boiling point distribution. Reactions at the higher reaction temperature of 430°C resulted in substantially higher conversion and production of lighter products than the reactions at 400°C. The LDPE reaction system was sensitive to the catalyst type, and yielded increased conversion and lighter products when Zeolyst 753 and NiMo/zeolite were used. By contrast, the conversion and product slate obtained from the LDPE and coal systems were low and showed no effect due to the different types of catalyst. Introduction of resid to the LDPE/coal system increased the reactivity of the system and allowed the catalysts to have a larger effect. The hydrocracking catalysts were the most active in producing more conversion and hexane soluble material. Comparison of the effect of increasing the reaction time up to 5 h with 1 wt.% catalyst loading to the effect of increasing the catalyst loading from 1 wt.% to 10 wt.% for a reaction time of 1 h showed that increased reaction time was much more effective than catalyst loading in converting the solid LDPE to liquid reaction products.

The reactivity of different coal and residuum combinations in coprocessing

Abstract This investigation evaluated the reactions of a variety of different coal and residuum combinations in coprocessing and the types of reaction products achieved. The coals ranged in rank from bituminous to lignite while the residua ranged from those with high asphaltene and metal contents to those which were waxy and had low metal contents. Catalytic coprocessing reaction conditions of 425°C and 60 minutes were selected on the basis of the largest differences observed in the products achieved with two quite different combinations. Coprocessing reaction products from the different combinations were compared and showed that substantial upgrading occurred with all combinations regardless of coal rank or residuum type. Lower rank lignite and subbituminous coals produced higher levels of hexane soluble materials regardless of the residuum used. Deashed Elkhorn coal showed less upgrading than Elkhorn under equivalent conditions. Residuum properties of metal content, Ramsbottom carbon, specific gravity and sulfur content appeared to be related to the production of different products from coprocessing. Lignite and subbituminous coal yielded a higher contribution of coal-derived material to be hexane soluble product fraction and a lower contribution to the asphaltene fraction than did the bituminous coals. Most of the heavier fractions were produced from coal regardless of the coal and residuum combination used.