Coal For Liquefaction Research Articles

Building methodology for evaluating the effects of direct coal liquefaction using coal structure-chemical index

As a semi-theoretical and semi-empirical method, structure-chemical index has classified the utilization of coals with different coalification degrees and petrographic constituents in Russia. In this work, the formulas of structure-chemical index were simplified to building methodology for evaluating the utilization of coals in direct coal liquefaction (DCL). Nineteen coals from Xinjiang, China, were characterized by ultimate analysis and thermal gravimetric analysis, and the corresponding DCL products were evaluated. After the calculation of structure-chemical index, 12 coals fall into the liquefaction zone, and exhibit higher H/C ratios and faster pyrolysis rates, which are helpful to coal liquefaction reaction. Therefore, the conversion rates and oil yields are more than 85.0% and 65.0%, respectively, for coals in the liquefaction zone, and less than 80.0% and 50.0% for coals out of the zone.

A new technological classification of low-rank coal on the basis of Polish deposits

Proposed technological classification of low-rank coal has two stages. First part, presented in graphic form, sets the rank of coal, grade of coal and its petrographic character. In order to assess the rank and distinguish various subcategories of low-rank coal, random reflectance of ulminite B/collotelinite has been applied. Simplified petrographic composition of humic coal allowed – on the basis of the content of macerals from huminite group (vitrinite – for bright brown coal) – to distinguish subcategories of low rank coal. Ash content of coal recalculated to dry basis determines – in proposed first stage of the classification – the grade of coal. Second stage of technological classification is presented as codification system, while it distinguishes following types of low rank coal: energetic coal (type 21), coal for gasification (type 22) as well as coal for liquefaction (type 23). Coal types are defined through chemical, technological and petrographic criteria. Every single type of low-rank coal has its own unique technological code, consisting of main and supplementary parameters. Main code allows to determine the possibility of its use in certain technologies, while supplementary code precisely characterizes the parameters important for those applications. Technological quality of tested coal has been presented with use of code number, which digits have been set on the basis of division into classes within tested parameters.

Evaluation of four kinds of promising Chinese coals for liquefaction

Evaluation of four kinds of promising Chinese coals for liquefaction

97/00871 Effects of surface-active agents on molybdenum adsorption onto coal for liquefaction

This study focuses on the synthesis of NiMo-based catalysts in both bulk and coated forms, using ion-exchangeable silica-doped hydrous titanium oxide (HTO:Si) supports. These catalysts were evaluated and compared against commercial NiMo-based catalysts (Amocat 1C and Shell 324) with respect to the hydrogenation of pyrene and the hydrodesulfurization/hydrodenitrogenation of coal-derived liquids. For pyrene hydrogenation, both bulk and supported (coated) NiMo/HTO:Si catalysts performed better than commercial benchmark catalysts on either a catalyst weight or an active metals basis. For both hydrodesulfurization and hydrodenitrogenation of coal-derived liquids in a trickle-bed reactor, the supported and bulk forms of the NiMo/HTO:Si catalysts nearly equalled the overall performance of the commercial catalysts at 3.45, 6.89 and 10.3 MPa and were superior on a total active metals basis. Extensive catalyst characterization was performed to explain the enhanced activity of the NiMo/HTO:Si materials.

97/00906 Improvement of coal for liquefaction

97/00906 Improvement of coal for liquefaction

97/00205 Explosive pretreatment of coal for liquefaction by the use of aqueous solvent mixture

97/00205 Explosive pretreatment of coal for liquefaction by the use of aqueous solvent mixture

96/03481 Characterization of coals for liquefaction using image analysis

96/03481 Characterization of coals for liquefaction using image analysis

水素消費特性に基づいた石炭の反応性および液化反応機構

Reaction mechanism of coal liquefaction and coal reactivity of 10 different coals for liquefaction were examined with an excess amount of tetralin at 723K under 10MPa of nitrogen gas atmosphere. The amount of naphthalene formed from tetralin during coal liquefaction was measured by FID-GC for the determination of hydrogen consumptions of coals.Coal was considered consisting of three different reactive components, I0, C1 and C2 defined from their hydrogenation characteristics. The component I0 was inherently inert in the present reaction condition. The component C1 formed consecutively oils and gases via preashaltenes and asphaltenes with consuming hydrogen. On the other hand, the component C2 formed oils and gases directly without consuming external hydrogen from the solvent and the gas phase.Hydrogen consumptions for various coals were predicted by the initial content of C1 in original coals within negligible small error. The amount of hydrogen consumed for formation of preaphaltenes and asphaltenes was not as predominant as that for oil formation involving gases formed. These results, furthermore, showed that reaction selectivities between intermolecular hydrogen of tetralin and gaseous hydrogen were different even in the same reaction condition, i.e. temperature and pressure. It was suggested that the difference among chemical structures of solvent having transferable hydrogen affected an efficient hydrogen utilization in coal liquefaction and that the role of hydrogen donor solvent might be enhanced by hydrogenation of aromatic ring during heating in the presence of catalyst.

Comments on the reactivity of low-rank coals in liquefaction

This communication discusses the subject of the relative reactivities of low-rank and bituminous coals in liquefaction. Accounts given by several researchers have provided seemingly contradictory results. An explanation is presented to reconcile these opposing views.

Coals for Synthetic-Fuel production

The authors review the quality requirements of coals for liquid fuels production. In the USSR the most suitable coals are found in the Kansk-Achinsk and Kuznetsk Basins. Tables show the chemical and maceral compositions of brown and sub-bituminous coals from a number of regions of the USSR, as well as the reserves of these coals. The coalfields are classified into 4 groups according to the suitability of their coals for liquefaction.

Reactivity of hydrolysed coals in liquefaction

A hvA bituminous, a subbituminous and a lignite coal have been hydrolysed by 20–30% aqueous caustic solution at 100–300 °C and total pressure from ambient to 8.3 MPa (1200 psi). Reactivity of these pretreated coals toward liquefaction has been examined. The conversion to benzene-soluble material (BS) and oil increases, and the preasphaltene and char residue decreases after pretreatment. Improvement in the conversion to the BS fraction is only marginal for the pretreated bituminous coal, but substantial for the low-rank coals. For the subbituminous coal, the liquefaction reactivity (conversion to BS) increases with the severity of hydrolysis pretreatment. Analyses of chemical compositions, 1H n.m.r. nuclei distributions and hydroxyl concentrations of the acid-insoluble hydrolysis coal extracts indicate that both O and S are enriched in the extracts with half of the oxygen atoms being in hydroxyl forms. The hydroxyl concentrations of the extracts (acid-insoluble) are ≈2 to 3 times higher than their parent coals. Coal activation by this alkali pretreatment is explained by the hydrolytic attacks on ether C–O linkages, and the removal of some constituents rich in oxygen functional groups which are responsible for poor liquefaction behaviour.