Jaroslav Machek

Kinetics and mechanism of the KOH — catalyzed methanolysis of rapeseed oil for biodiesel production

The reaction of rapeseed oil with methanol catalyzed by KOH is described by a model consisting of two sequences of consecutive competitive reactions. The first sequence expresses the methanolysis of rapeseed oil to methyl esters (biodiesel) whereas the second sequence describes the always present side reaction-saponification of glycerides and methyl esters by KOH. The proposed chemical model is described (after rational simplifications) by a system of differential kinetic equations which are solved numerically by two independent computing methods. The thus obtained theoretical kinetic and equilibrium results are compared numerically and/or graphically with the experimental parameters. The latter were obtained by the determination of the relevant components in the actual reaction mixture by analytical methods. According to the experimental results, the proposed reaction scheme is fulfilled with the probability of ca. 78%. The optimal average rate constants and equilibrium constants of individual reaction steps of the discussed scheme are introduced. The limitations of the proposed reaction model are discussed.

Biodiesel fuel from rapeseed oil, methanol, and KOH. Analytical methods in research and production

The enumeration of the analytical methods used in the production of biodiesel from rapeseed oil and methanol catalyzed by KOH and published till 1997 is given. Some of our original methods for individual or simultaneous determination of the main components in the reaction mixture are described. All these methods can be also used to analyse the non-equilibrium complex and heterogencous mixture.

Mechanism of selective oxidation of methanol over stannic oxide-molybdenum oxide catalyst

The mechanism of the selective oxidation of methanol on Sn-Mo oxide catalyst with molar ratio Mo/(Mo + Sn) = 0.3 is investigated. The interaction of methanol and its oxidation products (i.e. formaldehyde and methyl formate) is studied by FT-IR spectroscopy. The data are interpreted on the basis of a reaction mechanism which contains 10 elementary steps. The behaviors of the surface species (methoxy, formate and dioxymethylene groups) are compared with those monitored on other systems and the catalyst requirements for the title reaction are discussed.

Sorption of Acetic and Propionic Acids and Propanal on a Molybdenum-Vanadium Oxide Catalyst

It has been found by gas chromatography that the equilibrium adsorption of propanal, propionic and acetic acids on molybdenum-vanadium oxide catalyst can be described by the Langmuir adsorption isotherm. The existence of carboxylates on the catalyst surface has been proved by IR spectroscopy.