The sulfur issue in C4 used for MTBE
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Is the sulfur content in the C4 feedstock used in MTBE production the same as that in the residual C4? Do your plants collect such data? Shouldn’t the total sulfur content in the C4 be transferred to the MTBE product? The total sulfur content in the residual C4 is lower than that in the feedstock
It is beyond doubt that most of the sulfur in C4 is transferred to the MTBE product. The sulfur content in C4 before etherification is around 10–30 ppm, while the sulfur content in MTBE products can exceed 100 ppm at its highest levels
Could anyone provide the test data? Carbon tetrathiide content in the MTBE feed, carbon tetrathiide content remaining in MTBE, and total sulfur content in MTBE
In the pre-ether C4 fraction, the sulfides are mainly disulfides and thiols. The majority of the dithiethers transfer to MTBE, the thiol portion goes to M, and the remaining sulfur ends up in the carbon tetraether. Dithiethers have high boiling points; during the sampling and analysis of C4 compounds, some of these dithiethers liquefy and adhere to the inner walls of the sampling bags, resulting in analysis values for the total sulfur content in C4 compounds that are lower than the actual values. In the ether-derived C4 compounds, thiols are the predominant components, and this effect is relatively minor. Therefore, although most of the sulfur in the carbon tetra group before the ether ends up in M, the total sulfur content in the carbon tetra group after the ether and that before it appear to be similar based on the analysis data.
A sulfur balance needs to be established. Methanethiol in the n-C4 fraction of the general feedstock will partially convert to methyl tert-butyl ether during etherification, while the disulfides mostly end up in MTBE.