Rapeseed iodine value

Significant differences in fuel standards also exist among different countries (2, 14-18 Table 1). In the European Union (EU), member countries have adopted a standard requiring an iodine value of less than 115 (15, 16), 120 (14), or 125 (18). This iodine value reflects the upper extreme iodine value of canola (low erucic acid rapeseed) oil. The American Society for Testing Measures (ASTM) and Italian National Standards Body (UNI) standards do not include iodine value (2, 17) and thus allow higher iodine value oils such as soy and sunflower. 

Some new rare-earth based oxide catalysts are used to partially hydrogenated the rapeseed oil. The binary oxide Ce-Ni-O presents a good selectivity in the partial hydrogenation but a large extent of Z/E isomerization. The ratio of the iodine value (IV) variation over the pourpoint (PP) variation is lower than one. The introduction of aluminium in the catalyst formulae leads to a signiHcant decrease in the pourpoint variation due to the quasi-elimination of the Z/E isomerization. The oils obtained are more resistant to oxidation. 

Figure 1 Rapeseed oil hydrotreatment on Ce-Ni-O (Ni/Ce = 2). Iodine value versus the reaction temperature.

Rapeseed oil hydrotreatment. Ratio of the iodine value variation A(/V) over the )ourpoint variation A (P P) on rare-earth oxide based catalysts. ... 

Figure 6 Rapeseed oil hydrotreatment. Iodine value Vs the pourpoint.

Figure 7 Oxidation enthalpy values (DSC experiments) versus the iodine value of partially hydrogenated rapeseed oil.

Because of the presence of highly unsaturated fatty acids (as indicated by a high iodine value IV = 117) the rapeseed oil shows poor stability. It must be partially hydrogenated to increase this stability. The rapeseed oil conversion and the product distribution both depend on the Ni/Ce ratio of the mixed Ni-Ce-oxides and on the temperature. These catalwts appear more selective than Ni alone but lead to an important Z/E isomerization which gives rise to a drastic increase in the pourpoint value, llie use of a temaiy oxide (Ce-Ni-Al) allows a decrease in the extent of the Z/E isomerization. The results depend on the relative amount of each metal and the isomerization can be almost totally eliminated. Moreover, from some DSC experiments under an oxidative atmosphere, it appears that the resistance to oxidation can be improved, even at relatively high temperatures. 

The development of low-erucic acid rapeseed edible oil cultivars began after the identification of the discussed genetic sources of low erucic acid in both rapeseed species. Generic breeding objectives were still to develop locally adapted rapeseed cultivars with improved productivity and seed quality. Selection in both species was for maturity, seed yield, uniformity, lodging resistance, oil content, and iodine value in the oil. Seed quality improvement now included seed oil containing less than 5% erucic acid. 

On a pilot scale, epoxidation of both rapeseed mefliyl esters (RME) and higholeic sunflower methyl esters (HOSME) generally yields 85-90%. Epoxidized RME have oxirane values ranging from 4.5 to 5.2 and iodine values ranging from 5 to 1.7. Epoxidized HOSME have oxirane values ranging from 4.5 to 5 and iodine values ranging from of 1.7 to 0. The fatty acid compositions of expoxidized methyl esters determined by GC are given in Table 5. 

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