SYNTHESIS OF HYDROCARBONS AND CHEMICALS FROM CO AND H2
SECTION III
SYNTHESIS OF HIGH MELTING POINT WAXES
SUMMARY
The attached report covers laboratory work carried out by Kaiser-Wilhelm-Institut on the synthesis of high boiling waxes over Ruthenium catalyst. The results have been published in 1940-1941. They are mainly of theoretical interest.
Content.
THE SYNTHESIS OF HIGH MELTING POINT WAXES
1. General Introduction.
The use of Ruthenium as a catalyst for the production of high M.P. wax from CO and H2 was published in 1941 in “Breunnstoff Chemie”. 19.22 P. 226, the monthly magazine published by Kaiser Wilhelm Institut at Muehlheim. Copies of this paper are available in the United States for ready reference. The information obtained on the subject is briefly given in this report.
The process is mostly of theoretical interest and was not carried out beyond the laboratory stage.
A patent application was filed on May 1938 disclosing the use of Ruthenium (and /or catalysts containing Ru) at temperatures from 150 to 280° C and pressures above 30 atm. for the production of solid aliphatic hydrocarbons from CO and H2.
2. Catalyst.
The catalyst is prepared by melting Ruthenium with KNO3 and KOH to give potassium ruthenate which is dissolved in water and boiled under addition of methylalcohol. RuO2 is precipitated, filtered, washed, and dried. The oxide is reduced with synthesis gas (CO:H2=1:2) at 150° C and atmospheric pressure.
The catalyst may however be prepared by different methods. The essential requirement is that Ruthenium be present in as great dispersion as possible. Carriers, such as Kieselguhr may be used, but they have apparently no effect on the synthesis.
3. Operating Conditions.
The yield in hard wax increases with pressure and decreases with temperature. Optimum conditions seem to be 195° C at 150 atm. pressure
Space velocities from 1-2 liter gas/hr/gm Ru are used. The yields given by KWI are 150-160 g/m3 ideal feed gas.
The catalyst is quite susceptible to poisoning by sulphur, but with a pure feed gas, its life is exceedingly long. A two year run was made with one charge without any catalyst regeneration.
It should be noted that I.G. Leuna tried to duplicate the results without success. They obtained a brown product containing only 40% hard wax. The catalyst furthermore lost its activity within a few days. It appears that sulphur containing gas may have been used.
4. The Products
The product is a wide mixture of high boiling waxes. The paraffins are mostly exclusively straight chain hydrocarbons with only a small percent of tertiary carbon atoms.
The waxes were separated by known methods such as extraction at increasing temperatures and different solvents.
Individual waxes with molecular weights of 10,000 were found having a melting point of around 140° C. This seems to be the maximum melting point. Increased mol. weight does not further influence the melting point.
5. Reference.
The following German document is available at the library of the Bureau of Ships in Washington, D.C.