Coal hydroliquefaction

The use of a deuterium tracer in this research makes it possible to obtain new information regarding the reactions involved in the formation of these compounds. Since reactions of this type result in a loss of hydrogen donor capability of the solvent, research in this area is important to improve the efficiency of coal hydroliquefaction and the recycleability of the solvent. 

The results have shown that spinning/falling basket autoclaves can be used effectively for gathering data on coal hydroliquefaction, a single contact being representative of steady state conditions. As with other types of reactors for coal liquefaction, the catalysts were deactivated to a constant activity but the rate of deactivation was much more rapid in tiie autoclaves. 

The results have shown that, for the hydrogenation of the aromatic compounds providing a large proportion of the H-donors in recycle solvents, the extent of cracking (apart from acenaphthylene and diboizothiophene) was relatively small at 400 C. Consequently, at this temperature for a run time of 2 h with catalysts normally applied to coal hydroliquefaction, loss... 

The conversion of polar asphaltenes (lumped with non-eluted asphaltenes) as a function of process severity, expressed by hydrogen content in the liquid product, is shown in Figure 7. Amocat IB and HDS-1443 show a significantly high conversion of polar asphaltenes at a given process severity. It is worth noting that Amocat IB and HDS-1442, the Co-Mo version of HDS-1443, have been found to be active catalysts for coal hydroliquefaction (4). 

Lemberton, J.L. and M. Guisnet, Phenanthrene Hydroconversion as a Potential Test Reaction for the Hydrogenation and Cracking Properties of Coal Hydroliquefaction Catalysts., Appl. Catal., 13,181-192,1984. 

A question of considerable interest in coal hydroliquefaction chemistry is the amount and nature of "organically bound metals in the coal. One reason for this interest is the observation that when supported metal direct conversion catalysts are used in liquefaction reactors, a primary mode of deactivation is metals deposition Q, 2). In particular, recent work at the Pittsburgh Energy Technology Center (PETC) (4,5) and elsewhere (3) has indicated very high levels of titanium deposition on supported Co Mo catalysts used in the fixed bed continuous reactor system. It has been suggested that the culprits in such deposition are soluble metal species (6 9) The analyses of a Western Kentucky (Homestead) hvBb feed coal and of material deposited between the catalyst pellets in the fixed bed reactor at PETC (4) are shown in Table I. 

Scheme B. Treatment with anhydrous HC1 was applied to the entire filtered liquid product of coal hydroliquefaction diluted with an equal volume of n-hexane.

Scheme C. The entire filtered liquid product of coal hydroliquefaction was mixed with an equal volume of n-hexane to obtain a precipitate of n — Ce insolubles. It is worth noting that, at this point, further treatment of the raffinate with dry HC1 to precipitate the remaining basic nitrogen compounds gave essentially the same overall weight of precipitate as Scheme B.

These coal liquids originally were intended to serve as boiler fuels. The sulfur content may be sufficiently low to qaulify them as replacement for high-sulfur coal, and bring sulfur dioxide emissions within acceptable limits. However, for large boilers, such as major base load power plants, pollution control via coal hydroliquefaction probably is not competitive with stack gas scrubbing (I). 

To determine potential raw material impacts on brown coal hydroliquefaction, the 15 lithotypes were converted into liquid products using various techniques (18) ... 

Hydrogenation conditions were 1-2 g model ether, initial hydrogen pressure 6 MPa, reaction time 1 hour with catalyst loadings similar to those used for coal hydroliquefaction studies. Further details are outlined elsewhere (2,5). 

Different types of other coal liquefaction processes have been also developed to convert coals to liqnid hydrocarbon fnels. These include high-temperature solvent extraction processes in which no catalyst is added. The solvent is usually a hydroaromatic hydrogen donor, whereas molecnlar hydrogen is added as a secondary source of hydrogen. Similar but catalytic liquefaction processes use zinc chloride and other catalysts, usually under forceful conditions (375-425°C, 100-200 atm). In our own research, superacidic HF-BFo-induced hydroliquefaction of coals, which involves depolymerization-ionic hydrogenation, was found to be highly effective at relatively modest temperatnres (150-170°C). 

Relationship Between Coal Characteristics and Its Reactivity on Hydroliquefaction... 

It is well known that the characteristics of coal differ widely according to the age of the coal formation as well as to the location of coal, etc. And the reactivity during hydroliquefaction depends on the characteristics of coals. This relationship will he a guidance to select and develop coal mines. Many parameters to indicate the reactivity of coal have heen proposed (l, 2, 2). Among these parameters, carhon content, volatile matter content, value of H/C atomic ratio, reactive macerals content, etc. are reported to he relatively closely related parameters to coal reactivity. However, these relations are usually found only in limited reaction conditions. Therefore, attempts to find better parameters still continue. 

Analytical data on coals used in this study are presented in Tables 2 and 3. Hydroliquefaction data on coals used in this study are summarized in Tables k and 5 ... 

Table k. Reaction conditions and results of hydroliquefaction on coals used in the study of the wide range... 

It is well known that coal reactivity depends on the solvent, the conditions of hydroliquefaction, and the composition of the coal. Different extracting solvent results in different conversion, but it can be considered that the different conversion shows a similar tendency to coal reactivity. Thus, it is desirable that the parameter representing coal reactivity shows essentially the same tendency, despite the conditions of hydroliquefaction. Accordingly comparison of parameters was carried out, using some previously reported results (2, 3). 

As stated before, volatile carbon % is considered to be one of the most important parameters of hydroliquefaction. Also a fairly good linear relationship between the volatile carbon % in coal and low temperature tar yield from coal is found in Morwell brown coals, based on the data from the State Electricity Commission of Victoria (SECV) in Australia, as shown in Fig.9 Therefore, the low temperature tar yield is also estimated to be an important parameter. In addition, the color tone of brown coal (lithotypes) is shown in this figure. From this figure, it is observed that both volatile carbon % and low temperature tar yield are in a fairly good relation to the color tone of brown coal. Thus, as proposed by the Australian researchers, the color tone of brown coal is considered to be an important parameter. 

Figure 8.3. Gas-Liquid Fluidized Bed C"Ebullating" Reactor for Hydroliquefaction of Coal CKampiner, in Winnacker-Kuehler, Chemische Technolagie 52, 19723. ...

Correlation of Coal Properties with Hydroliquefaction Reactivity A Brief Review... 

Since the earliest days of coal liquefaction processing and research, the need for correlations of coal properties with coal reactivity under direct hydroliquefaction conditions has been recognized by coal scientists. This article traces the history of reactivity correlations from the earliest work of Bergius through the classic work at the Bruceton Bureau of Mines during the 1940 s to the most recent advances in this subject. Particular emphasis in this review is placed on an examination of the contributions of Professor Peter Given and his co-workers. Reactivity methodologies and techniques for correlation are presented and critically evaluated for utility and applicability as predictive tools. 

Hydroliquefaction of Coal Liquids in Spinning and Falling Basket Autoclaves... 

Fresh and used catalysts (CoMo, NiMo, ZnMo and ZnW) were used in hydroliquefaction experiments with batches of Point of Ayr coal liquid. One series of experiments was carried out at 400 C for 2 h with all four of the catalysts using five repeat contacts. A second series used only CoMo over three repeat contacts considered variations in reaction time and... 

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