TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Catalyst: The second catalyst comprises platinum (Pt) of at least 75 (preferably at least 85, especially at least 95) wt.% on cerium oxide (CeO2). The first and the second catalysts are present in a first reactor, being the same reactor. The first catalyst is an acidic catalyst comprising tungsten oxide (WO3) supported on zirconium oxide (ZrO2). The second catalyst is catalyst catalyzing de-carbonylation reactions, but to a very limited extent water-gas-shift (WGS) reactions, such as a catalyst comprising PdZCeO2 as the catalyzing specie.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: In method (M1), the second catalyst catalyzes de-carbonylation reactions, where the second catalyst is selected from catalysts catalyzing water-gas-shift (WGS), hydrogenation and de-carbonylation reactions (preferably hydrogenation reactions). The third catalyst catalyzes de-hydration reactions. The method (M1) further involves: providing hydrogen in stoichiometric excess with regard to glycerol; the glycerol is provided as mixture with water, where the concentration of glycerol in the mixture of glycerol and water is 1-75 (preferably 10-50, especially 15-30) wt.%. The mixture of glycerol and water is provided in gas phase, where the conversion of glycerol to acrolein and the conversion of acrolein to the hydrocarbon are performed in gas phase. The conversion ratio of glycerol is more than 80 (preferably more than 90, especially more than 95, particularly more than 99)%. The glycerol in the mixture of glycerol and water is produced by algae and/or microorganisms, where the glycerol is diluted before conversion to acrolein by recycling some of the steam and/or water produced in various reaction(s) of the method. The temperature of the glycerol/water-mixture, when provided is 100-600 (preferably 200-400, especially 250-350) degrees C. The glycerol is converted to acrolein at a pressure of 0.1-100 (preferably 1-40, especially 2-10) bar. The pressure at which glycerol is converted to acrolein and acrolein to ethane is 3.5-4.5 bar. SPECIFIC COMPOUNDS - Preparation of 4 compounds are specified as the hydrocarbon i.e. ethane (Ia); ethene; propane; propene.    EXAMPLE - Production of ethane was carried out as follows: In the first layer a first catalyst (56 g) consisting tungsten oxide (WO3) (10 wt.%) supported on zirconium oxide (ZrO2) in grains of the size 20-30 mesh, was used. On top of this, another layer with a second catalyst (15 g) consisting platinum (Pt) (4 wt.%) on CeO2 was applied as grains of the size 20-30 mesh. The inlet liquid stream consisted glycerol (20 wt.%) in water fed to the preheater. A gas stream of 400 ml/minute of hydrogen was also fed to the pre-heater. The liquid stream was preheated and evaporated, to 300 degrees C, prior entering the first reactor. The inlet of reactor was held at 320 degrees C and a pressure of 4 bar gauge was applied over the reactors. The outlet stream was cooled down in the condenser 10 and the water was condensed in a chiller. The liquid stream was collected in a sample vessel, while the gas stream was collected in a Tedlar gas bag.