Glyoxal Oxidation Method of Oxalic Acid
Glyoxal has strong reducibility, so it can be rapidly oxidized to oxalic acid under the action of strong oxidizing nitric acid. Due to factors such as raw material supply, price, and technology, this method has poor market competitiveness and has not been industrialized.
In addition, there are other synthetic methods for oxalic acid:
(1) Carbon dioxide preparation method: Carbon dioxide is first reduced to the intermediate
CO2
and then converted into other organic substances. Oxalic acid is obtained by irradiating various carbon dioxide systems with electrochemical methods and γ-rays, sunlight, or high-pressure mercury lamps.
(2) Alkali melting method using cellulose-rich materials: A mixture of cellulose-rich materials (such as waste wood, chaff, etc.) and inorganic strong alkali is co-melted at 513–558 K to generate more than 50% oxalate. The oxalate crystals are precipitated by crystallization, and then sulfuric acid is used to obtain the finished oxalic acid. This method has a simple process for preparing oxalic acid, but the single-pass conversion rate is low (less than 35%), alkali consumption is high, and environmental pollution is severe.
(3) Coal raw material production method: Prepared from various peats as raw materials. For example, oxalic acid is produced from peat of the genera Sphagnum and Polytrichum via nitric acid oxidation. The reaction is carried out at 343 K for 8–9 hours, with a yield of up to 95%. When raw materials such as coal tar are used to produce oxalic acid, the yield also reaches 51%.

Shandong Pulisi Chemical Co., Ltd. – Oxalic Acid (Ethanedioic Acid) Specialist