Hydrocracking of kraft lignin (Indulin-AT) and of model compounds p-ethylguaiacol and dehydrodihydrodiisoeugenol (DDDI) was studied with tetralin äs hydrogen donor in the temperature ränge 375 to 400° C. It was found that aliphatic oxygen functions reacted most rapidly. The aromatic methoxyl groups underwent either methyl-oxygen or ring-oxygen cleavage forming catechol and phenol groups, respectively. The former process is more prevalent at higher temperatures. Side-chain cleavages resulted in the general lowering of molecular weight and formation of monomeric phenols. Careful analysis of the latter products suggested that these cleavages occurred mostly between the aand ß-carbon atoms but cleavages between the aromatic ring and the -carbon also occurred. Upon prolonged hydrocracking, guaiacols and catechols disappeared while a mixture of phenol, cresols and ethyl phenols was relatively resistant towards further conversions.

Thermal Degradation of Kraft Lignin in Tetralin

Pretreatment of coal by reaction with subcritical steam enhances its performance in direct liquefaction. Illinois No. 6 coal, first reacted with 51 atm of steam for 15 min at 340 °C, was liquefied ...

Improvement of coal direct liquefaction by steam pretreatment

Publisher Summary This chapter discusses the conversions of bituminous coals in water systems and several aspects of the process, including the kinetics and mechanism of the conversions. The mineral matter in coals includes abundant quantities of silica, several aluminosilicates, pyrite (FeS2) as the major sulfide, and smaller quantities of oxides and carbonates. Conversion in H2/H2O systems is very sensitive to the mineral content of the coal, with the conversion falling in the absence of the mineral material. FeS2, a major component in coal mineral matter, can be very reactive under hydrothermal conditions. The effectiveness of the CO/water system in conversion has been discussed in the chapter. The increase in the level of ultimate coal conversion upon switching to D2O as the medium shows that the interplay of subtle kinetic features of the reducing system can substantially affect the convertibility of a given coal.

Coal Conversion in Carbon Monoxide–Water Systems

In this paper, we describe the development of a laboratory-scale delayed coker and present results of an investigation on the recovered liquid from the coking of decant oil and decant oil/coal mixtures. Using quantitative gas chromatography/mass spectroscopy (GC/MS) and {sup 1}H and {sup 13}C NMR, a study was made of the chemical composition of the distillate liquids isolated from the overheads collected during the coking and co-coking process. {sup 1}H and {sup 13}C NMR analyses of combined liquids from coking and co-coking did not show any substantial differences. These NMR results of coking and co-coking liquids agree with those of GC/MS. In these studies, it was observed that co-coking with coal resulted in a decrease in the paraffins contents of the liquid. The percentage of cycloparaffins, indenes, naphthalenes, and tetralins did not change significantly. In contrast, alkyl benzenes and polycyclic aromatic hydrocarbons in the distillate were higher in the co-coking experiments which may have resulted from the distillation of thermally cracked coal macromolecules and the contribution of these molecules to the overall liquid composition. 40 refs., 3 figs., 13 tabs.

Delayed coking of decant oil and coal in a laboratory-scale coking unit

Application of Kalman filter to determination of coal liquefaction mechanisms using discrete time models

We would like to emphasize the importance of asphaltols in the initial stages of coal liquefaction Their propensity toward char formation at temperatures comparable to liquefaction temperatures, their high degree of functionality, and the fact that they are the predominant, primary products of coal liquefaction, indicate that much valuable information critical in SRC process control and design could be obtained by a more thorough understanding of their chemistry and structure

Asphaltols: keys to coal liquefaction

The development of improved liquefaction technology requires a thorough understanding of the chemistry and mechanisms involved in converting coals to liquid fuels. The primary objectives of EPRI Project 410-1 were to develop such fundamental understanding of the thermal solvent refining of coal. This report constitutes the final report of a four year study. It consists of three volumes. The first volume contains a critical review of the chemistry and basic limitations of today's developing liquefaction processes; an overall summary of the significance of the results of the four-year project to present-day processes; and a detailed review of the last 1 1/2 years of the project. The second volume contains the bulk of the experimental work in the last 1 1/2 years of the project as well as a literature review of specific topics. Volume III contains the pertinent Appendices. Throughout this report, emphasis is placed on the initial phases of coal liquefaction with special attention to the chemical functionality, structure and properties of the initial products of coal. This chemistry is related to the basic constraints imposed on commercial processes such as achievable reaction times, temperatures, pressures, and production and chemical constitution of recycle solvents which are required for coalmore » conversion. In the critical review of limitations of present-day technology, we attempt to integrate the understanding of the chemistry developed and suggest possible means to improve these processes.« less

Nature and origin of asphaltenes in processed coals. Final report. [Especially of initial phases and products]

This report presents the results of the first year of a two-year effort aimed at obtaining a fundamental understanding of the chemical nature and structure of solubilized coals and the kinetics and mechanisms by which these liquefaction products are formed from various coals under solvent refinishing (SRC) conditions. Coal liquefaction was studied under somewhat mild reaction conditions and at very low conversions, as well as under conditions typical of SRC pilot plant operations in order to be able to follow the solubilization process more closely. A much more detailed investigation of the skeletal structures and chemical functionality of products was pursued than has previously been performed. (GRA)

The nature and origin of asphaltenes in processed coals. Annual report

Studies have been undertaken to develop a fundamental understanding of the chemistry and structure of coal and coal products and the mechanisms involved in the conversion of coal to soluble products under typical solvent refining conditions Illinois, Kentucky, and Wyoming coals were investigated Reactions were conducted in stirred autoclaves at contact times from 025 to 420 min using synthetic recycle solvents Reaction variables included particle size, coal preparation method, temperature, atmosphere, and solvent composition Products were characterized in detail utilizing newly developed liquid chromatographic methods Fractions were further characterized by wet chemical, polarographic, and a variety of spectroscopic techniques, and skeletal structures of SRC's and parent coals were derived The chemistry of typical recycle solvents was studied Systematic changes which occur during the transformation of coal into soluble and upgraded products were studied in detail Compositional changes monitored included aromatic contents and skeletal structure, and changes in functionality, molecular weight, and elemental composition Elucidation of the kinetics and mechanisms of functionality changes was aided by an extensive study of the chemistry of isolated SRC fractions and of model compounds under liquefaction conditions

Nature and origin of asphaltenes in processed coals: the chemistry and mechanisms of coal conversion to clean fuel. Annual report, March 1976--February 1977

Several significant new methods of study were developed. These included a novel fractionation procedure for the separation of soluble coal products into discrete chemical classes. With this chemical description of the Solvent Refined Coal (SRC) products, fundamental understanding of the mechanisms involved in coal conversion can be achieved and a chemical basis for process optimization may possibly be found. Procedures were also developed which allowed the study of the transformation of coal to soluble form under the conditions of pressure and temperature common to SRC processing, but at very short times (as short as 15 to 30 sec.). A synthetic solvent developed and used in this project is composed of a minimum number of known low boiling compounds that reflect the chemistry of actual recycle solvents. This solvent was easily separated and distinguished from coal products and, because of its simplicity, the chemistry of solvent-solvent and solvent-coal interactions could also be determined. The key findings of this work using these new tools are described in detail.

M. Farcasiu

Papers

Asphaltols: keys to coal liquefaction

Nature and origin of asphaltenes in processed coals. Final report. [Especially of initial phases and products]

The nature and origin of asphaltenes in processed coals. Annual report

Nature and origin of asphaltenes in processed coals: the chemistry and mechanisms of coal conversion to clean fuel. Annual report, March 1976--February 1977

Nature and origin of asphaltenes in processed coals. Annual report. [55 references]