Selective Oxidation at SABIC Innovative Catalysts and Technologies

Selective Oxidation at SABIC Innovative Catalysts and Technologies 

The paper overviews research carried out at SABIC Company in the last 15-20 years in the field of selective oxidation. Using different approaches, a number of effective catalysts were developed by proposing new or improving existing catalytic systems. On some of them reaction network and kinetics were studied that in combination with reaction engineering allowed elaborate process technology. The most advanced development is ethane direct oxidation to acetic acid which was commercialized at one of the SABIC plants. 

In the early 1990s SABIC management launched a research program on the conversion of low-weight paraffins and olefins to value-added monomers and chemicals. Since that time SABIC researchers have been actively involved in the development and study of catalysts for different selective oxidation reactions. Some of the oxidation reactions and catalyst compositions developed by them are listed in Table 11.1 along with the yields and selectivifies of target products. 

Ethylene conversion to acetic acid can be increased in at least two ways. One is making the catalyst surface more acidic, which will strengthen ethylene adsorption on the surface to give more time for its oxidation to acetic acid. A more acidic surface will also facilitate desorption of acetic acid thus reducing its surface over-oxidation to carbon oxides. This approach has been realized by adding small amounts of P, B and Te to the MoVNb oxide catalyst. Table 11.2 presents the results of adding phosphorus. 

Increasing the amount of phosphorus introduced into the MoVNh oxide catalyst decreased ethane conversion because of lower specific surface areas of P-promoted catalysts. Ethane conversion normalized to the catalyst surface area, as is seen from Table 11.2, did not change much. Selectivity to acetic acid (AA) increased and selectivity to ethylene decreased significantly with the amount of phosphorus in the catalyst, while their combined selectivity stayed roughly unchanged. These results imply that the phosphorus added to the MoVNb oxide catalyst indeed increased conversion of the intermediate ethylene to acetic acid. 

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