Quality of ethylene glycol produced from coal
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Why is the ethylene glycol produced via the coal chemical route (that is, ethylene glycol obtained through the hydrogenation of dimethyl oxalate) inferior to that produced via the petroleum route in terms of both color intensity and impurity content? How to improve?
Is the poor performance of the refining unit causing excessive impurities and poor color intensity?
The reason might be simple: from the outset, the quality standards for the product were based on those of petroleum ethylene glycol, and the equipment was likely designed with those standards in mind as well. For example, the impurities in petroleum-based ethylene glycol are 1, 2, 3, and 4, and there are corresponding equipment and technologies available to remove them. In contrast, the impurities in coal-based ethylene glycol are a, b, c, d, and e; since the raw materials and production processes are completely different, the equipment or methods used for petroleum-based ethylene glycol are not applicable in this case. It is recommended that you review the entire synthesis process, conduct a theoretical analysis of possible impurities, and then perform a full chromatographic analysis on the crude product before purification, in order to identify all the impurities present. This should be done for a set of samples rather than just one batch, so as to determine whether there is any correlation between these impurities and fluctuations in the process parameters. With such data, it will be possible to assess whether the current purification equipment is effective. The above are my estimates; they may not be accurate and are for reference only.