Deoxygenation of triglycerides over Co and Mo sulfides supported on a series of mesoporous molecular sieves (MCM-41) with varying Si/Al ratio has been investigated in this contribution. The catalysts were tested in a flow reactor at reaction temperatures 300 and 320°C, hydrogen pressures 2-11 MPa and space velocities 1-4 h -1 using refined rapeseed oil as a feedstock. Incorporation of Al into the framework of MCM-41 led to an increase of both conversion of triglycerides and selectivity to hydrocarbons, namely n-heptadecane and n-octadecane. However, the conversion of triglycerides was lower than that achieved over alumina supported CoMo. Moreover, the rather high selectivity to oxygenated products, as compared with alumina supports, has made possible a detailed description of the reaction intermediates and their dependence on the reaction conditions.
The role of the type of acid site (Broensted vs. Lewis) on the activity and selectivity of molecular sieve catalysts was investigated in ferrocene and toluene acylation. H-, Zn-, Fe-, Al- and La-forms of zeolite Beta, USY and mesoporous molecular sieves (Al)MCM-41, (Al)SBA-15 were tested. It was observed that addition of metal cations acting as Lewis acid sites can increase the acidity of various molecular sieve catalysts. No general relationship between the type of cation and conversion of individual substrate was found. While the highest activity in ferrocene acylation was observed after addition of Zn, in the case of toluene acylation Al-forms of catalysts were the most active. The results indicate that the acid strength of cationic Lewis sites controls their activity in acylation reactions.
Acylation of ferrocene and toluene with linear, branched and aromatic anhydrides and chlorides of different chain length was investigated over zeolite Beta with Si/Al ratio 12.5. It was found that the conversion of ferrocene increased from acetic to butyric anhydride/chloride and then decreased with further increasing of chain length. The selectivity to 1-acylferrocene was in all cases 100%. In the case of toluene acylation, the conversions of acylating agent increased with the chain length of acylating agent up to hexanoic derivatives then the conversion of acylating agent was almost constant. The selectivity to p-isomer in toluene acylation increased with the chain length. The lowest conversions in both cases were achieved with benzoic anhydride and benzoyl chloride.
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