PEP Review 85-1-1
Trimellitic Anhydride From m-Xylene
Published: December 1985
Mitsubishi Gas Chemical, in a joint venture with Amoco Chemicals, has constructed a 15,000 metric tons/yr unit in Japan to manufacture trimellitic anhydride from m-xylene. The process developed by MGC reacts m-xylene (contained in a mixed xylene stream) with carbon monoxide in the presence of a boron trifluoride catalyst and hydrogen fluoride solvent to form 2,4-dimethyl benzaldehyde. The 2,4-dimethyl benzaldehyde is isolated, purified, and catalytically oxidized with air in an aqueous medium to form trimellitic acid. In a subsequent step, the trimellitic acid is dehydrated to trimellitic anhydride, which is purified to meet commercial specifications.
In this review, we present a preliminary process design for the new route based on Mitsubishi Gas Chemical patents, along with estimated capital and production costs for a 33 million lb/yr and a 66 million lb/yr trimellitic anhydride unit.
For comparison, we present an updated and modified evaluation of the existing commercial route to trimellitic anhydride, oxidation of pseudocumene, practiced by Amoco, and an updated evaluation of the extraction of pseudocumene from C9-10 aromatics (Process Economics Report No. 66, issued in 1970).
The process appears competitive with the existing commercial route.