Water-induced gaseous formaldehyde decomposition using ruthenium organic crystalline particles

Abstract

Formaldehyde is a hydrogen-containing chemical that can react with water, and thus, formaldehyde–water has emerged as an attractive hydrogen storage system. However, formaldehyde is also a carcinogenic airborne pollutant released from paint, coatings and furniture. In this work, we innovatively propose a method for Ru(p-cymene) immobilization and prepare several novel ruthenium organic crystalline particles for formaldehyde decomposition. The ruthenium organic crystalline particles are bifunctional catalysts. On one hand, they exhibit high activity for hydrogen production from formaldehyde–water decomposition in water. The TOF reaches up to 2420 h⁻¹ at 90 °C when Ru-DAPM₂ is employed. On the other hand, ruthenium organic crystalline particles also have high activity for gaseous formaldehyde decomposition in air. Unlike the reported photocatalytic or thermocatalytic oxidation methods for gaseous formaldehyde removal, the ruthenium organic crystalline particles provided two reaction paths for formaldehyde decomposition: formaldehyde–water decomposition or the catalytic oxidation of formaldehyde. Formaldehyde mainly decomposes through water-induced reactions in moist air, and Ru-DAPM₂ exhibits 98% conversion for formaldehyde decomposition at 90 °C. We propose and prove the reaction process and mechanism for formaldehyde decomposition in air, and find that Ru-DAPM₂ first absorbs water vapor in air. The gaseous formaldehyde then dissolves in water, is converted into methanediol, undergoes the formaldehyde–water shift reaction, and produces hydrogen and formic acid. Formic acid is an essential intermediate during the reaction, and could further decompose into hydrogen and carbon dioxide. This work proposes a creative and distinct method for gaseous formaldehyde decomposition under air- or oxygen-free conditions.