One‐Step Esterification of Phosphoric, Phosphonic and Phosphinic Acids with Organosilicates: Phosphorus Chemical Recycling of Sewage Waste

• Published in: Angewandte Chemie International Edition Vol. 64; no. 10; pp. e202416487 - n/a
• Main Authors: Naganawa, Yuki, Sakamoto, Kei, Fujita, Akira, Morimoto, Kazuya, Ratanasak, Manussada, Hasegawa, Jun‐ya, Yoshida, Masaru, Sato, Kazuhiko, Nakajima, Yumiko
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 03.03.2025; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Acids; Antibiotics; Chemical recycling; Chemistry; Chemistry, Multidisciplinary; Direct conversion; Esterification; green sustainable chemistry; Phosphonic acids; Phosphoric acid; Phosphorus; Phosphorus compounds; Physical Sciences; Reagents; Recycling; Science & Technology; Sewage; silicon; Sludge; RESOURCES; ALKYL; BOND FORMATION; RECOVERY; silicon; esterification; green sustainable chemistry; MONOESTERS; PHOSPHATES; chemical recycling; DEHYDRATIVE CONDENSATION; SILICA; P(O)-OH COMPOUNDS; phosphorus; CYCLE
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202416487

Global concerns regarding the depletion and strategic importance of phosphorus resources have increased demand for the recovery and recycling. However, waste‐derived phosphorus compounds, primarily as chemically inert phosphoric acid or its salts, present a challenge to their direct conversion into high‐value chemicals. We aimed to develop an innovative technology that utilizes the large quantities of sewage waste, bypasses the use of white phosphorus, and enables esterification of phosphoric acid to produce widely applicable phosphate triesters. Tetraalkyl orthosilicates emerged as highly effective reagents for the direct triple esterification of 85 % phosphoric acid, as well as the esterification of organophosphinic and phosphonic acids. Furthermore, we achieved esterification of recovered phosphoric acid with tetraalkyl orthosilicate, thus pioneering a recycling pathway from sewage waste to valuable phosphorus chemicals. Experimental and theoretical investigations revealed a novel mechanism, wherein tetraalkyl orthosilicates facilitate multimolecular aggregation to achieve alkyl transfer from tetraalkylorthosilicate to phosphoric acid via multiple proton shuttling. Chemical recycling of phosphoric acid (H3PO4) recovered from sewage sludge ash into valuable phosphate triesters has been achieved via a novel esterification method with tetraalkyl orthosilicate. The approach offers an innovative recycling pathway, producing key industrial phosphorus chemicals without the use of white phosphorus while addressing phosphorus resource limitations and environmental impact.