Arthur R. Tarrer

High-temperature liquefaction of waste plastics

Abstract High-temperature liquefaction of commingled post-consumer plastics obtained from the American Plastics Council was studied. The liquefaction reaction was carried out in a tubing bomb micro-reactor with operating temperatures of ∼500°C, hydrogen pressures of ∼790kkPa cold and reaction times of 0–30 min. These high temperatures were used to reduce the residence time required for liquefaction. Reactions were carried out in the absence of catalysts. Total conversion and conversions to asphaltenes, oil, gas and coke were monitored. Total conversion as high as 100% was achieved. Gas yields up to 70% and oil yields as high as 60% were obtained. The kinetics of liquefaction of these waste materials was studied. Maximum yield of liquid product was obtained at ∼500°C and ∼5–10 min reaction time.

INVESTIGATION OF THE EFFECT OF AGGREGATE PRETREATMENT WITH ANTISTRIPPING AGENTS ON THE ASPHALT-AGGREGATE BOND

ABSTRACT Addition of Chemical antistripping agents (ASA)to asphalt has inherent disadvantages such as reduction of the effectiveness of ASA in hot asphalt and formation of relatively weak bond with the aggregate surface. To circumvent such problems, a novel approach of aggregate pretreatment with ASA was investigated in this study. The aggregate was pretreated with aqueous emulsions/solutions of different organic surface modifiers. The effectiveness of this aggregate pretreatment procedure was evaluated to ascertain the asphalt-aggregate bond strength using the boiling water test. Boiling water test was selected for its rapidity and simplicity. The

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.

Kinetic model development for single-stage coal coprocessing with petroleum waste

Abstract Coal coprocessing with waste petroleum materials achieves the dual purpose of upgrading both the coal and the waste materials economically. The kinetics of coal coprocessing with petroleum waste has been studied experimentally and modeled mathematically. A combined parallel and series reaction scheme was assumed for the coal liquefaction. Experiments were carried out in a tubing bomb microreactor at temperatures of 375 to 425°C, at reaction times of 15–120 min, with 10% coal loading and with 1250 psig pressure. Coal conversions as high as 98% were obtained during coprocessing. More than 70% conversion to oil is achieved at high temperatures and grease loadings. The effect of temperature and grease loading on coal liquefaction were also studied. A rigorous parameter estimation technique was employed to determine the parameters involved in the model. The model predictions are good for experimental conditions other than those used to determine the model parameters. Higher conversion and higher rate of liquefaction obtained during coprocessing were explained from the obtained kinetic rate parameter values.

X-Ray Fluorescence Analysis of Trace Elements in Coal and Solvent Refined Coal

Publisher Summary This chapter describes the research that was undertaken to ascertain the ability of energy dispersive X-ray fluorescence (EDXRF) analysis to determine trace element content of solvent refined coal (SRC). Rapid simultaneous quantitative analysis of a large number of elements is possible with EDXRF. In this research, around 17–20 elements were quantitatively analyzed in both raw feed coal and product SRC from the Wilsonville SRC Pilot Plant, Wilsonville, Alabama. It has been known that EDXRF is capable of analyzing coal and SRCs for elemental content. These analyses provide simultaneous results for several important elements, namely, sulfur, iron, and calcium, in addition to percent ash and liquefaction yield. These analyses presently take well over 2 hr per sample to complete, but by using EDXRF, this time can be reduced to about 1 hr per sample. EDXRF has an added feature in that it may be automated, leading to even shorter analysis times per sample. Thus, EDXRF can be concluded to be an effective tool that can provide very accurate and rapid analyses of trace elements in coals and SRC product.

Selectivity improvement in the solvent refined coal process 1. Detailed first-stage reaction studies: Coal mineral catalysis

Abstract The influence of various coal mineral additives on coal liquefaction, hydrogenation and desulfurization was studied. The specific minerals studied include SRC-residue, Kerr-McGee residue, SRC-residue ash, Kerr-McGee residue ash, hematite-1 (commercial grade ore), hematite-2 (reagent grade), magnetite, coal ash, and reduced iron. Comparisons were made of the effect of these mineral additives on hydrogen consumption, desulfurization, and selectivity for desulfurization over hydrogenation. The effect of oxidation temperature on the surface area and desulfurization activity of the oxidized residues was evaluated.

Selectivity improvement in the SRC process

Abstract The selectivity for hydrodesulfurization over hydrogenation has been examined in a new short residence time catalytic two-stage SRC process, which has the potential of producing a low-sulfur solid SRC product to meet the newly proposed EPA new point source emission standards (NPSES). In the first stage of the process, residence time and hydrogen consumption are minimized through the use of an inexpensive mineral catalyst (SRC residue ash) that has been treated under a combustion environment to improve its selectivity for hydrodesulfurization over hydrogenation. The second stage of the process involves hydrotreating the filtered liquid product with a commercial Co-Mo-Al catalyst, before splitting into a solid SRC and solvent recycle by distillation. Several process variables — such as type of coal, catalyst, temperature, hydrogen partial pressure, and reaction time — have been examined to provide information on hydrogen consumption, product distribution, sulfur removal, SRC yield and solvent quality. The results show that the ash of SRC residue can be used to selectively catalyze desulfurization over hydrogenation in SRC processing. Selectivity for desulfurization in two stage hydrodesulfurization of coal is improved by using high reaction temperatures, short residence times, the ash of SRC residue as a first stage catalyst, and Co-Mo-Al as a second stage catalyst. Two stage catalytic SRC processing is more selective for hydrodesulfurization than catalytic or non-catalytic single stage SRC processing.

Identification of clay minerals in coal by selective cation saturation

Abstract The accurate identification of clay minerals in coal is important because of their high relative abudance and because they give an indication of the environment of coal deposition. In addition, there is evidence that clay minerals may act catalytically in several coal liquefaction processes. Current methods used for identification of clay minerals in coal are shown to be subject to errors because the method of separation of the clay fraction leaves the clay partially or totally saturated with sodium. The sodium-saturated clay makes identification of smectite, vermiculite, and interstratified clay minerals very difficult, especially where one or more co-exist in the clay fraction. A method based upon selective cation saturation with potassium and magnesium is shown to allow identification of several additional clay species in the low-temperature ash of coal not detectable using the sodium-saturated clay.

Selectivity improvement in the solvent refined coal process 2. Detailed second-stage reaction studies: Hydrotreating of coal liquids

Abstract A two-stage process has been investigated for the production of a low-sulfur solid SRC-I type boiler fuel with a minimum consumption of costly hydrogen. The process employs a coal mineral with scavenging action in the first stage dissolver, followed by second stage hydrotreating of the dissolver effluent. This paper reports a detailed investigation of second-stage hydrotreating conditions designed to optimize the process with respect to maximum sulfur removal with minimum hydrogen consumption. The process variable space is experimentally mapped and modeled using appropriate reaction kinetic expressions. This model is then used to select optimum conditions for operation of the second-stage hydrotreating process for the production of a low-sulfur solid SRC product with minimum hydrogen consumption.