Removal of impurities from raw materials

In the process of producing 1,4-butanediol via the hydrogenation of dimethyl maleate, certain purity requirements are imposed on the raw material dimethyl maleate. The impurities that need to be removed mainly include: 1. Acidic impurities: These are removed through methods such as neutralization or alkaline washing. 2. Moisture: It is necessary to ensure that the moisture content in the raw materials is low; molecular sieves or other desiccants can typically be used for removal. 3. Impure dimethyl maleate isomers: There are two isomers of dimethyl maleate, with the cis isomer having higher activity; therefore, certain methods (such as extraction using boiling water solutions) are required to remove these isomers in order to ensure high selectivity and yield in the reaction. If these impurities are not effectively removed, they can cause catalyst deactivation and inefficient reactions, thereby affecting the yield and quality of the product. -

If this dimethyl maleate is prepared by reacting cycloanhydride with methanol, and p-toluenesulfonic acid is used as the catalyst. So, for dimethyl maleate as a raw material in downstream hydrogenation processes, are there any requirements regarding its p-toluenesulfonic acid content?

P-toluenesulfonic acid is commonly used as a catalyst in the reaction of maleic anhydride with methanol to produce dimethyl maleate. As a raw material for downstream hydrogenation processes, the finished dimethyl maleate generally requires a low content of p-toluenesulfonic acid, and its purity needs to be improved through methods such as impurity removal. p-Toluenesulfonic acid is a strong acid catalyst; if an excessive amount of it remains in the hydrogenation reaction, it can lead to catalyst deactivation and affect the selectivity of the products, thereby reducing yield and quality. Therefore, in actual production, it is generally required that the content of p-toluenesulfonic acid in the dimethyl maleate product be kept at a low level, in order to ensure the efficient progress of the downstream hydrogenation reaction. -

Okay, I understand. So what are the desulfurization catalysts actually used in industrial operations nowadays? It is said to be a modified activated carbon adsorption desulfurizer. It is generally required that the content of p-toluenesulfonic acid in dimethyl maleate after purification be less than 5 mg/M3. As for the lifespan of the desulfurization agent and whether it can be reused, etc., that’s unknown. May I ask: do you have any practical information on industrial applications in this area? If there are any, please send me a message. We want to improve the performance of this desulfurizer in order to extend its lifespan or the cycle during which it can be reused. I wonder if it’s possible? :handshake