Hydrogenation of Double Bond - from Sitosterol to Sitostanol

Palladium is known to be a metal that works catalytically in the system. Various supports can be used for Pd, such as active carbon, mesoporous materials, and polymers. All of them deactivate in the sitosterol hydrogenation, most probably because of sulfur and phosphorus impurities present in the raw material, which originates from the tall oil production, a side process of chemical pulping. 

The sitosterol hydrogenation and deactivation kinetics was determined in a shaking constant-pressure batch reactor by using the new type of synthetic support material (mesoporous carbon Sibunit) for palladium (4wt% Pd) [55]. 

Preliminary kinetic studies revealed that the catalyst deactivated it was difficult to achieve a complete conversion of the substrate (sitosterol) in a batch experiment, but the conversion approached a limiting value, depending on the amount of catalyst added. By the addition of higher amounts of the catalyst, higher conversions were obtained even so the standard plots of the substrate conversion versus the mass 

The rates of the elementary steps can be formulated in a conventional manner, and the quasi-steady state hypothesis is applied to the adsorbed substrate (A ). The 

A detailed mathematical treatment gave the following models for the main substrate (A) and product (R)  

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