Coal liquefaction Bergius process

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. 

The first direct coal liquefaction process was developed and patented by Bergius from Germany in 1913 and, therefore, is often referred to as the Bergius process. The world s first industrial-scale direct coal liquefaction plant was built in Leuna, Germany, in 1927 with an annual fuel production of 10,0001. By 1939, Germany built 12 direct coal liquefaction plants with a combined annual fuel production of about 4.23 million metric tons, which supplied about 70% of the aviation fuel and 50% of the transportation fuel for German troops during World War II. 

The Germans used coal liquefaction on a commercial scale from 1930 to the end of the second World War. They found that a catalyst could enhance liquid yields and help remove heteroatoms. The Bergius process used an iron oxide-aluminum catalyst at a 2-3% by coal weight concentration. 

In recent years, it has been realized that mineral matter plays an important role in coal liquefaction (9-11), similar to the role of the added catalyst in the Bergius process. Several experimental techniques have been used to study the effects of minerals on coal liquefaction and to identify the specific catalytic phase (12). Most studies (12-14) strongly imply that the iron sulfides are the roost active species, and the other minerals appear to have little effect on enhancement of liquid yield or quality. 

Methods of coal liquefaction have been available since the beginning of the twentieth century but the cost has initiated searches for more effective new processes. For example, in the Bergius process for direct coal liquefaction, the coal is treated with hydrogen under pressure at 450°C (840°F) in the presence of a solvent and an iron oxide catalyst. The activity of this catalyst is low, however, because the solid iron oxide cannot enter the macromolecular network structure of the insoluble coal. Semianthracite coal, which only contains a small amount of volatile components, cannot be converted by this process. 

The Bergius process (Storch, 1945), like the Pott-Broche process, is more of historical interest than current commercial interest but it was a process that literally paved the way for the development of catalytic liquefaction of coal. 

There are two types of processes available for coal liquefaction, namely direct conversion of coal with hydrogen, invented by Friedrich Bergius in 1913, and coal extraction with hydrogenating solvents, first tested in a pilot plant by Alfred Pott and Hans Broche in 1935. The products from both processes can be further hydrogenated in a second stage to obtain fuels. 

Direct Liquefaction Process in which coal is subjected to hydrogenation under high pressure and at a high temperature, thereby converting it directly into a synthetic liquid fuel also known as the Bergius process. 

Neither the idea nor the practice of producing oil from coal is new. As early as 1819, Charles Macintosh distilled naphtha from coal for the purpose of waterproofing textiles. However, the major breakthroughs in coal liquefaction did not occur until the period between the early 1900 s, when the two processes long used as the starting points for producing oil from coal—the Bergius and Fischer-Tropsch methods— were developed. 

Matthias Pier (1882-1965), a German chemist, worked with Emil Fischer and Walter Nernst during his studies. After WWI, he joined BASF and worked on ammonia and methanol synthesis. After BASF had purchased the patent on coal liquefaction from Bergius in 1925, he developed this process further. He found better and sulfur-resistant catalysts and increased the yield of fuels by arranging the process in two steps, liquid-phase hydrogenation and gas-phase hydrotreating of the intermediate product. Thus, the process is therefore mostly known as the Bergius-Pier process. 

The first process was studied by Berthelot in 1867 and was further developed in Germany by Bergius in 1910. The early Bergius process involved the reaction of H2 under atmospheric pressure with pulverized coal suspended in an oil heated to about 450°C in the presence of a catalyst such as stannous formate or Mo. The liquid oil product is separated from the solid residue and processed as ordinary crude oil. Modem developments in this coal liquefaction approach include (1) Exxon Donner Solvent (EDS) process, (2) the HRI H-Coal process, and (3) the Gulf Solvent Refined Coal SRC-II process. The major improvement of these processes over the Bergius process is in the catalyst used, allowing for milder reaction conditions. 

Bergins (1) A coal liquefaction process (also called hydroliquefaction) invented in Germany in 1913 by F. Bergius and subsequently developed by IG Farbenindustrie. The inventor, together with C. Bosch, was awarded the Nobel Prize for chemistry for this invention in 1931. A pilot plant was operated at Rheinau near... 

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