The publication of this new process in 1902 not only attracted a number of imitators to the scene, but also aroused the interest of the chemical industry in pure nitrogen. Nitrogen compounds (calcium cyanamide, ammonia) were gaining increasing importance as fertilizers.
In a modified rectification process, the team in Höllriegelskreuth achieved nitrogen purification as well in 1903. Linde sold the first such plant to an Italian customer in 1905. And by 1910 the team, under the direction of Friedrich Linde and Rudolf Wucherer, had developed a "two-column apparatus," which delivered pure oxygen and pure nitrogen at the same time, at a low cost.
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The Linde plant facilities in Höllriegelskreuth in 1909 (top) and 1929
(bottom). |
Further uses for rectification
Another interesting field of research came about with the emerging demand by the incandescent light industry for inert gases to fill electric light bulbs. Argon in particular was successfully extracted using a modified separation process starting in 1912.
In 1906, the rectification experts also started working in a study cooperative with Prof. Adolf Frank and Heinrich Caro on separating water gas into its constituent parts hydrogen, carbon monoxide, carbon dioxide, nitrogen and methane.
After extensive research trials in 1909 and 1910, the Höllriegelskreuth team succeeded in producing pure hydrogen. The members of the study cooperative joined together to form a company to take advantage of the "Linde-Frank-Caro process," with exclusive sales rights going to Linde. One early plant with an hourly yield of 2,000 cubic meters of hydrogen and 700 cubic meters of nitrogen was sold to the Badische Anilin- und Sodafabrik (BASF) for the synthetic production of ammonia. Other plants were ordered by margarine factories for hydrogenation.
Experience with water gas separation led in the 1920s to coke gas separation at low temperatures into its valuable components of hydrogen, nitrogen, methane and ethylene, in which rectification played a major role.
The knowledge needed for the complex coke gas separation process finally came from the principle for producing from natural gas and oil - a major prerequisite for the production of plastics after the Second World War.